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Perrotta MM, Lucibelli F, Mazzucchiello SM, Fucci N, Hay Mele B, Giordano E, Salvemini M, Ruggiero A, Vitagliano L, Aceto S, Saccone G. Female Sex Determination Factors in Ceratitis capitata: Molecular and Structural Basis of TRA and TRA2 Recognition. INSECTS 2023; 14:605. [PMID: 37504611 PMCID: PMC10380613 DOI: 10.3390/insects14070605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 06/28/2023] [Accepted: 07/01/2023] [Indexed: 07/29/2023]
Abstract
In the model system for genetics, Drosophila melanogaster, sexual differentiation and male courtship behavior are controlled by sex-specific splicing of doublesex (dsx) and fruitless (fru). In vitro and in vivo studies showed that female-specific Transformer (TRA) and the non-sex-specific Transformer 2 (TRA2) splicing factors interact, forming a complex promoting dsx and fru female-specific splicing. TRA/TRA2 complex binds to 13 nt long sequence repeats in their pre-mRNAs. In the Mediterranean fruitfly Ceratitis capitata (Medfly), a major agricultural pest, which shares with Drosophila a ~120 million years old ancestor, Cctra and Cctra2 genes seem to promote female-specific splicing of Ccdsx and Ccfru, which contain conserved TRA/TRA2 binding repeats. Unlike Drosophila tra, Cctra autoregulates its female-specific splicing through these putative regulatory repeats. Here, a yeast two-hybrid assay shows that CcTRA interacts with CcTRA2, despite its high amino acid divergence compared to Drosophila TRA. Interestingly, CcTRA2 interacts with itself, as also observed for Drosophila TRA2. We also generated a three-dimensional model of the complex formed by CcTRA and CcTRA2 using predictive approaches based on Artificial Intelligence. This structure also identified an evolutionary and highly conserved putative TRA2 recognition motif in the TRA sequence. The Y2H approach, combined with powerful predictive tools of three-dimensional protein structures, could use helpful also in this and other insect species to understand the potential links between different upstream proteins acting as primary sex-determining signals and the conserved TRA and TRA2 transducers.
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Affiliation(s)
| | - Francesca Lucibelli
- Department of Biology, University of Naples "Federico II", 80126 Napoli, Italy
| | | | - Nicole Fucci
- Department of Biology, University of Naples "Federico II", 80126 Napoli, Italy
| | - Bruno Hay Mele
- Department of Biology, University of Naples "Federico II", 80126 Napoli, Italy
| | - Ennio Giordano
- Department of Biology, University of Naples "Federico II", 80126 Napoli, Italy
| | - Marco Salvemini
- Department of Biology, University of Naples "Federico II", 80126 Napoli, Italy
| | - Alessia Ruggiero
- Institute of Biostructures and Bioimaging (IBB), CNR, 80131 Napoli, Italy
| | - Luigi Vitagliano
- Institute of Biostructures and Bioimaging (IBB), CNR, 80131 Napoli, Italy
| | - Serena Aceto
- Department of Biology, University of Naples "Federico II", 80126 Napoli, Italy
| | - Giuseppe Saccone
- Department of Biology, University of Naples "Federico II", 80126 Napoli, Italy
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Saccone G. A history of the genetic and molecular identification of genes and their functions controlling insect sex determination. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2022; 151:103873. [PMID: 36400424 DOI: 10.1016/j.ibmb.2022.103873] [Citation(s) in RCA: 11] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2022] [Revised: 11/01/2022] [Accepted: 11/02/2022] [Indexed: 06/16/2023]
Abstract
The genetics of the sex determination regulatory cascade in Drosophila melanogaster has a fascinating history, interlinked with the foundation of the Genetics discipline itself. The discovery that alternative splicing rather than differential transcription is the molecular mechanism underlying the upstream control of sex differences in the Drosophila model system was surprising. This notion is now fully integrated into the scientific canon, appearing in many genetics textbooks and online education resources. In the last three decades, it was a key reference point for starting evolutionary studies in other insect species by using homology-based approaches. This review will introduce a very brief history of Drosophila genetics. It will describe the genetic and molecular approaches applied for the identifying and cloning key genes involved in sex determination in Drosophila and in many other insect species. These comparative analyses led to supporting the idea that sex-determining pathways have evolved mainly by recruiting different upstream signals/genes while maintaining widely conserved intermediate and downstream regulatory genes. The review also provides examples of the link between technological advances and research achievements, to stimulate reflections on how science is produced. It aims to hopefully strengthen the related historical and conceptual knowledge of general readers of other disciplines and of younger geneticists, often focused on the latest technical-molecular approaches.
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Affiliation(s)
- Giuseppe Saccone
- Department of Biology, University of Naples Federico II, Via Cinthia 26, 80126, Naples, Italy.
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Yuan JW, Song HX, Chang YW, Yang F, Du YZ. Transcriptome analysis and screening of putative sex-determining genes in the invasive pest, Frankliniella occidentalis (Thysanoptera: Thripidae). COMPARATIVE BIOCHEMISTRY AND PHYSIOLOGY. PART D, GENOMICS & PROTEOMICS 2022; 43:101008. [PMID: 35752128 DOI: 10.1016/j.cbd.2022.101008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2022] [Revised: 05/11/2022] [Accepted: 06/08/2022] [Indexed: 06/15/2023]
Abstract
The invasive insect pest, Frankliniella occidentalis, is a well-known vector that transmits a variety of ornamental and vegetable viruses. The mechanistic basis of sex determination in F. occidentalis is not well understood, and this hinders our ability to deploy sterile insect technology as an integrated pest management strategy. In this study, six cDNA libraries from female and male adults of F. occidentalis (three biological replicates each) were constructed and transcriptomes were sequenced. A total of 6000 differentially-expressed genes were identified in the two sexes including 2355 up- and 3645 down-regulated genes. A total of 149 sex-related genes were identified based on GO enrichment data and included transformer-2 (tra2), fruitless (fru), male-specific lethal (msl) and sex lethal (sxl); several of these exhibited sex-specific and/or sex-biased expression in F. occidentalis. This study contributes to our understanding of the sex-determined cascade in F. occidentalis and other members of the Thysanoptera.
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Affiliation(s)
- Jia-Wen Yuan
- College of Horticulture and Plant Protection, Institute of Applied Entomology, Yangzhou University, Yangzhou 225009, China
| | - Hai-Xia Song
- College of Horticulture and Plant Protection, Institute of Applied Entomology, Yangzhou University, Yangzhou 225009, China
| | - Ya-Wen Chang
- College of Horticulture and Plant Protection, Institute of Applied Entomology, Yangzhou University, Yangzhou 225009, China
| | - Fei Yang
- Department of Entomology, Texas A&M University, College Station, TX, USA
| | - Yu-Zhou Du
- College of Horticulture and Plant Protection, Institute of Applied Entomology, Yangzhou University, Yangzhou 225009, China; Joint International Research Laboratory of Agriculture and Agri-Product Safety, The Ministry of Education, Yangzhou University, Yangzhou, China.
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Bayega A, Oikonomopoulos S, Gregoriou ME, Tsoumani KT, Giakountis A, Wang YC, Mathiopoulos KD, Ragoussis J. Nanopore long-read RNA-seq and absolute quantification delineate transcription dynamics in early embryo development of an insect pest. Sci Rep 2021; 11:7878. [PMID: 33846393 PMCID: PMC8042104 DOI: 10.1038/s41598-021-86753-7] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/28/2020] [Accepted: 03/10/2021] [Indexed: 11/21/2022] Open
Abstract
The olive fruit fly, Bactrocera oleae, is the most important pest for the olive fruit but lacks adequate transcriptomic characterization that could aid in molecular control approaches. We apply nanopore long-read RNA-seq with internal RNA standards allowing absolute transcript quantification to analyze transcription dynamics during early embryo development for the first time in this organism. Sequencing on the MinION platform generated over 31 million reads. Over 50% of the expressed genes had at least one read covering its entire length validating our full-length approach. We generated a de novo transcriptome assembly and identified 1768 new genes and a total of 79,810 isoforms; a fourfold increase in transcriptome diversity compared to the current NCBI predicted transcriptome. Absolute transcript quantification per embryo allowed an insight into the dramatic re-organization of maternal transcripts. We further identified Zelda as a possible regulator of early zygotic genome activation in B. oleae and provide further insights into the maternal-to-zygotic transition. These data show the utility of long-read RNA in improving characterization of non-model organisms that lack a fully annotated genome, provide potential targets for sterile insect technic approaches, and provide the first insight into the transcriptome landscape of the developing olive fruit fly embryo.
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Affiliation(s)
- Anthony Bayega
- McGill Genome Centre, Department of Human Genetics, McGill University, Montréal, Québec, Canada
| | - Spyros Oikonomopoulos
- McGill Genome Centre, Department of Human Genetics, McGill University, Montréal, Québec, Canada
| | - Maria-Eleni Gregoriou
- Laboratory of Molecular Biology and Genomics, Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Greece
| | - Konstantina T Tsoumani
- Laboratory of Molecular Biology and Genomics, Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Greece
| | - Antonis Giakountis
- Laboratory of Molecular Biology and Genomics, Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Greece
| | - Yu Chang Wang
- McGill Genome Centre, Department of Human Genetics, McGill University, Montréal, Québec, Canada
| | - Kostas D Mathiopoulos
- Laboratory of Molecular Biology and Genomics, Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Greece.
| | - Jiannis Ragoussis
- McGill Genome Centre, Department of Human Genetics, McGill University, Montréal, Québec, Canada.
- Department of Bioengineering, McGill University, Montréal, Québec, Canada.
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Abstract
BACKGROUND The Oriental fruit fly, Bactrocera dorsalis, is a highly polyphagous invasive species with a high reproductive potential. In many tropical and subtropical parts of the world it ranks as one of the major pests of fruits and vegetables. Due to its economic importance, genetic, cytogenetic, genomic and biotechnological approaches have been applied to understand its biology and to implement the Sterile Insect Technique, currently a part of area-wide control programmes against this fly. Its chromosome complement includes five pairs of autosomes and the sex chromosomes. The X and Y sex chromosomes are heteromorphic and the highly heterochromatic and degenerate Y harbours the male factor BdMoY. The characterization of the Y chromosome in this fly apart from elucidating its role as primary sex determination system, it is also of crucial importance to understand its role in male biology. The repetitive nature of the Y chromosome makes it challenging to sequence and characterise. RESULTS Using Representational Difference Analysis, fluorescent in situ hybridisation on mitotic chromosomes and in silico genome resources, we show that the B. dorsalis Y chromosome harbours transcribed sequences of gyf, (typo-gyf) a homologue of the Drosophila melanogaster Gigyf gene, and of a non-LTR retrotransposon R1. Similar sequences are also transcribed on the X chromosome. Paralogues of the Gigyf gene are also present on the Y and X chromosomes of the related species B. tryoni. Another identified Y-specific repetitive sequence linked to BdMoY appears to be specific to B. dorsalis. CONCLUSIONS Our random scan of the Y chromosome provides a broad picture of its general composition and represents a starting point for further applicative and evolutionary studies. The identified repetitive sequences can provide a useful Y-marking system for molecular karyotyping of single embryos. Having a robust diagnostic marker associated with BdMoY will facilitate studies on how BdMoY regulates the male sex determination cascade during the embryonic sex-determination window. The Y chromosome, despite its high degeneracy and heterochromatic nature, harbours transcribed sequences of typo-gyf that may maintain their important function in post-transcriptional mRNA regulation. That transcribed paralogous copies of Gigyf are present also on the X and that this genomic distribution is maintained also in B. tryoni raises questions on the evolution of sex chromosomes in Bactrocera and other tephritids.
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The transformer-2 and fruitless characterisation with developmental expression profiles of sex-determining genes in Bactrocera dorsalis and B. correcta. Sci Rep 2020; 10:17938. [PMID: 33087807 PMCID: PMC7578103 DOI: 10.1038/s41598-020-74856-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 10/07/2020] [Indexed: 12/12/2022] Open
Abstract
Sex determination in tephritid fruit flies involves a signaling cascade of alternatively spliced genes. The Transformer (TRA) and Transformer-2 (TRA-2) complex establishes an autoregulatory loop switching sex-specific splicing of tra pre-mRNA in females. The TRA/TRA-2 complex also regulates the sex-specific splicing of downstream effector genes, doublesex (dsx) and fruitless (fru). In Ceratitis capitata, a Maleness-on the-Y (MoY) gene modulates sex-specifically spliced Cctra pre-mRNA and results in the breakdown of the Cctra autoregulatory loop in males. In this study, the tra-2 and fru genes were characterised in two key pests, Bactrocera dorsalis and B. correcta. The tra-2 genes showed high degrees of conservation among tephritids. The complex gene organisation for each of Bdfru and Bcfru were identified. There are sex-specific and non sex-specific transcripts generated by alternative promoters as found in Drosophila melanogaster and other insects. RNAi knockdown of Bdtra transcripts showed that BdTRA controls the sex-specific splicing of Bddsx and Bdfru pre-mRNAs. Developmental expression analysis shows that multiple splice variants of Bdtra and Bctra RNAs are present before and during cellular blastoderm formation and that the mature sex-specific variants become fixed later in embryogenesis. Furthermore, the BddsxM splice variants are found in early embryos at the beginning of gastulation, but BdfruM does not appear until the larval stage. We proposed that the zygotic tra loop is initiated in both female and male embryos before becoming automatised or abolished by MoY, respectively.
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Peng W, Yu S, Handler AM, Zhang H. Transcriptome Analysis of the Oriental Fruit Fly Bactrocera dorsalis Early Embryos. INSECTS 2020; 11:insects11050323. [PMID: 32456171 PMCID: PMC7290859 DOI: 10.3390/insects11050323] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 03/31/2020] [Revised: 04/28/2020] [Accepted: 04/28/2020] [Indexed: 12/01/2022]
Abstract
The oriental fruit fly, Bactrocera dorsalis (Hendel), is one of the most devastating and highly invasive agricultural pests world-wide, resulting in severe economic loss. Thus, it is of great interest to understand the transcriptional changes that occur during the activation of its zygotic genome at the early stages of embryonic development, especially the expression of genes involved in sex determination and the cellularization processes. In this study, we applied Illumina sequencing to identify B. dorsalis sex determination genes and early zygotic genes by analyzing transcripts from three early embryonic stages at 0–1, 2–4, and 5–8 h post-oviposition, which include the initiation of sex determination and cellularization. These tests generated 13,489 unigenes with an average length of 2185 bp. In total, 1683, 3201 and 3134 unigenes had significant changes in expression levels at times after oviposition including at 2–4 h versus 0–1 h, 5–8 h versus 0–1 h, and 5–8 h versus 2–4 h, respectively. Clusters of gene orthology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) annotations were performed throughout embryonic development to better understand the functions of differentially expressed unigenes. We observed that the RNA binding and spliceosome pathways were highly enriched and overrepresented during the early stage of embryogenesis. Additionally, transcripts for 21 sex-determination and three cellularization genes were identified, and expression pattern analysis revealed that the majority of these genes were highly expressed during embryogenesis. This study is the first assembly performed for B. dorsalis based on Illumina next-generation sequencing technology during embryogenesis. Our data should contribute significantly to the fundamental understanding of sex determination and early embryogenesis in tephritid fruit flies, and provide gene promoter and effector gene candidates for transgenic pest-management strategies for these economically important species.
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Affiliation(s)
- Wei Peng
- Key Laboratory of Horticultural Plant Biology (MOE), State Key Laboratory of Agricultural Microbiology, China-Australia Joint Research Centre for Horticultural and Urban Pests, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China; (W.P.); (S.Y.)
- College of Life Sciences, China Jiliang University, Hangzhou 310018, China
| | - Shuning Yu
- Key Laboratory of Horticultural Plant Biology (MOE), State Key Laboratory of Agricultural Microbiology, China-Australia Joint Research Centre for Horticultural and Urban Pests, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China; (W.P.); (S.Y.)
| | - Alfred M. Handler
- USDA/ARS, Center for Medical, Agricultural and Veterinary Entomology, 1700 SW 23rd Drive, Gainesville, FL 32608, USA;
| | - Hongyu Zhang
- Key Laboratory of Horticultural Plant Biology (MOE), State Key Laboratory of Agricultural Microbiology, China-Australia Joint Research Centre for Horticultural and Urban Pests, College of Plant Science and Technology, Huazhong Agricultural University, Wuhan 430070, China; (W.P.); (S.Y.)
- Correspondence:
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Du Q, Wen L, Zheng SC, Bi HL, Huang YP, Feng QL, Liu L. Identification and functional characterization of doublesex gene in the testis of Spodoptera litura. INSECT SCIENCE 2019; 26:1000-1010. [PMID: 29808584 DOI: 10.1111/1744-7917.12608] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/28/2018] [Revised: 04/22/2018] [Accepted: 05/10/2018] [Indexed: 06/08/2023]
Abstract
Fusion of the testis occurs in most Lepidoptera insects, including Spodoptera litura, an important polyphagous pest. Testicular fusion in S. litura is advantageous for male reproduction, and the molecular mechanism of fusion remains unknown. Doublesex influences the formation of genitalia, the behavior of courtship, and sexually dimorphic traits in fruit-fly and silkworm, and is essential for sexual differentiation. However, its purpose in the testis of S. litura remains unknown. The doublesex gene of S. litura (Sldsx) has male-specific SldsxM and female-specific SldsxF isoforms, and exhibits a higher expression level in the male testis. At the testicular fusion stage (L6D6), Sldsx attained the highest expression compared to the pre-fusion and post-fusion periods. Moreover, Sldsx had a higher expression in the peritoneal sheaths of testis than that of germ cells in the follicle. CRISPR/Cas9 (Clustered Regularly Interspaced Short Palindromic Repeats/Cas9) was applied to S. litura to determine the role of Sldsx. A mixture of single guide RNA messenger RNA and Cas9 protein (300 ng/μL each) was injected into eggs within 2 h following oviposition. CRISPR/Cas9 successfully induced genomic mutagenesis of Sldsx at G0 generation. The mutant males had smaller testis surrounded by less tracheae. Moreover, the mutant males had abnormal external genitalia and could not finish mating with wild-type females. Additionally, testes were fused for almost all mutant males. The results showed that Sldsx was not related to testicular fusion, and is required for both testis development and the formation and function of external genitalia in S. litura. The main roles of doublesex on the male are similar to other insects.
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Affiliation(s)
- Qian Du
- Guangzhou Key Laboratory of Insect Development Regulation and Applied Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Liang Wen
- Guangzhou Key Laboratory of Insect Development Regulation and Applied Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Si-Chun Zheng
- Guangzhou Key Laboratory of Insect Development Regulation and Applied Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Hong-Lun Bi
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Science, Chinese Academy of Sciences, Shanghai, China
| | - Yong-Ping Huang
- Key Laboratory of Insect Developmental and Evolutionary Biology, Institute of Plant Physiology and Ecology, Shanghai Institutes for Biological Science, Chinese Academy of Sciences, Shanghai, China
| | - Qi-Li Feng
- Guangzhou Key Laboratory of Insect Development Regulation and Applied Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, China
| | - Lin Liu
- Guangzhou Key Laboratory of Insect Development Regulation and Applied Research, Institute of Insect Science and Technology, School of Life Sciences, South China Normal University, Guangzhou, China
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Molecular Characterization and Functional Study of Insulin-Like Androgenic Gland Hormone Gene in the Red Swamp Crayfish, Procambarus clarkii. Genes (Basel) 2019; 10:genes10090645. [PMID: 31455039 PMCID: PMC6770367 DOI: 10.3390/genes10090645] [Citation(s) in RCA: 17] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2019] [Revised: 08/07/2019] [Accepted: 08/21/2019] [Indexed: 12/13/2022] Open
Abstract
The androgenic gland (AG) is a male-specific endocrine organ that controls the primary and secondary sexual characteristics in male crustaceans. More evidence indicates that the insulin-like androgenic gland hormone gene (IAG) is the key male sexual differentiation factor, particularly the application of RNA interference (RNAi) technology on IAG. In this study, the full-length cDNA of IAG (termed PcIAG) was isolated from the red swamp crayfish, Procambarusclarkii. Tissue distribution analysis showed that in addition to its expression in the AG of male P. clarkii, PcIAG was widely expressed in female tissues and other male tissues. The PcIAG protein was detected in the reproductive and nervous systems of adult male P. clarkii. Additionally, RNAi results showed that the PcIAG expression could be silenced efficiently, and the male sperm maturation and release possibly present a transient adverse interference at lower doses (0.1 μg/g and 1 μg/g) of PcIAG–dsRNA (PcIAG double-stranded RNA). Dramatically, the expression level of PcIAG increased sharply shortly after the injection of higher doses (5 μg/g and 10 μg/g) of PcIAG–dsRNA, which might accelerate the maturation and release of sperm. Moreover, the expression of PcSxl (P. clarkii Sex-lethal) was detected by Quantitative Real-Time PCR (qPCR) after the injection of PcIAG–dsRNA to explore whether the PcIAG gene regulates the PcSxl gene, and we found that the PcIAG did not directly regulate PcSxl in P. clarkii. The study could help accelerate the progress of PcIAG functional research and provide a useful reference for the single-sex selective breeding of P. clarkii.
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Thongsaiklaing T, Nipitwattanaphon M, Ngernsiri L. The transformer2 gene of the pumpkin fruit fly, Bactrocera tau (Walker), functions in sex determination, male fertility and testis development. INSECT MOLECULAR BIOLOGY 2018; 27:766-779. [PMID: 29931748 DOI: 10.1111/imb.12517] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
The insect transformer2 (tra2) gene has a prevalent role in cooperating with the sex-determining gene transformer (tra) to direct female differentiation. Here, we report the identification and characterization of Btau-tra2, the tra2 orthologue of the pumpkin fruit fly, Bactrocera tau, an invasive agricultural pest. The Btau-tra2 gene produces three transcript variants. However, only two transcripts can be examined; one is present at all developmental stages in the soma and germline of both sexes and the other one is specific to the embryo and the germline. Knocking down the function of Btau-tra2 produced a male-biased sex ratio and some intersexes. Consistent with a role in sex determination, the obtained intersexual and male sterility phenotypes express a mix of male and female splice variants of the tra and doublesex (dsx) orthologues, indicating that Btau-tra2 has a conserved splicing regulatory function and acts together with/upstream of tra and dsx. In addition, some males obtained from the knock down are fertile but their fertilities are extremely reduced. Moreover, almost all surviving RNA interference (RNAi) males harbour testes having some defects in their external morphologies. Most notably, the body size of a few surviving RNAi flies was two-to threefold increased with respect to the normal size. Our findings suggest that Btau-tra2 is involved in male fertility and may also have an unprecedented role in body size control besides its conserved role in sex determination.
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Affiliation(s)
- Thanaset Thongsaiklaing
- Center of Agricultural Biotechnology, Kasetsart University, Nakon Pathom, Thailand
- Center of Excellence on Agricultural Biotechnology: (AG-BIO/PERDO-CHE), Bangkok, Thailand
- Division of Animal Science, Faculty of Agriculture, Princess of Naradhiwas University, Narathiwat, Thailand
| | | | - Lertluk Ngernsiri
- Department of Genetics, Faculty of Science, Kasetsart University, Bangkok, Thailand
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López-Cuadros I, García-Gasca A, Gomez-Anduro G, Escobedo-Fregoso C, Llera-Herrera RA, Ibarra AM. Isolation of the sex-determining gene Sex-lethal (Sxl) in Penaeus (Litopenaeus) vannamei (Boone, 1931) and characterization of its embryogenic, gametogenic, and tissue-specific expression. Gene 2018; 668:33-47. [PMID: 29758296 DOI: 10.1016/j.gene.2018.05.024] [Citation(s) in RCA: 17] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/28/2018] [Revised: 05/03/2018] [Accepted: 05/07/2018] [Indexed: 12/11/2022]
Abstract
The Pacific white shrimp Penaeus vannamei is the most cultured shrimp species around the world. Because females grow larger than males, the culture of 'only females' is of great interest, but knowledge on sex determination and differentiation is required for producing only females. In an effort to obtain information associated with reproduction in P. vannamei, transcriptomic data from female gonads was generated, and partial sequences of a transcript were identified as Sex-lethal (Sxl). Its characterization indicated that, differently from other penaeids in which this gene has been isolated, there are six isoforms of the Sxl transcript in P. vannamei (PvanSxl 1-6). These isoforms result from alternative splicing at three splice sites (SS1, SS2, SS3). The first splice-site is unique to P. vannamei, as it has not been reported for other Arthropod species; the second splice-site (SS2) is common among crustaceans, and the third splice-site (SS3) is also unique to P. vannamei and when spliced-out, it is always together with SS2. All isoforms are expressed during embryogenesis as well as gametogenesis of both genders. The two shorter isoforms, PvanSxl-5 and PvanSxl-6, which result from the splicing of SS2 and SS3, were found mostly expressed in adult testis, but PvanSxl-6 was also expressed in oocytes during gametogenesis. During oogenesis, the second largest isoform, PvanSxl-2, which splices-out only SS1, and PvanSxl-4 that splices-out SS1 and SS2 were highly expressed. These two isoforms were also highly expressed during embryonic development. In situ hybridization allowed pinpointing more specifically the cells where the PvanSxl transcripts were expressed. During embryogenesis, hybridization was observed from the one-cell stage embryo to late gastrula. In the female gonad in previtellogenesis, hybridization occurred in the nucleus of oocytes, whereas in secondary vitellogenesis the transcript also hybridized cytoplasmic granules and cortical crypts. Finally, in situ hybridization corroborated the expression of PvanSxl also in the male gonad during spermatogenesis, mostly occurring in the cytoplasm from spermatogonia and spermatocytes.
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Affiliation(s)
- Itzia López-Cuadros
- Centro de Investigaciones Biológicas del Noroeste, S.C. (CIBNOR). Programa de Acuacultura, Av. Instituto Politécnico Nacional No. 195, Col. Playa Palo de Santa Rita, La Paz, Baja California Sur C.P. 23096, Mexico
| | - Alejandra García-Gasca
- Centro de Investigación en Alimentación y Desarrollo A.C., (CIAD) Unidad Mazatlán, Av. Sábalo-Cerritos S/N. Col. Estero del Yugo, C.P. 82000 Mazatlán, Sinaloa, Mexico
| | - Gracia Gomez-Anduro
- Centro de Investigaciones Biológicas del Noroeste, S.C. (CIBNOR). Programa de Acuacultura, Av. Instituto Politécnico Nacional No. 195, Col. Playa Palo de Santa Rita, La Paz, Baja California Sur C.P. 23096, Mexico
| | - Cristina Escobedo-Fregoso
- Centro de Investigaciones Biológicas del Noroeste, S.C. (CIBNOR). Programa de Acuacultura, Av. Instituto Politécnico Nacional No. 195, Col. Playa Palo de Santa Rita, La Paz, Baja California Sur C.P. 23096, Mexico; CONACYT, Consejo Nacional de Ciencia y Tecnología, Av. Insurgentes Sur 1582, Ciudad de México 03940, Mexico
| | - Raúl A Llera-Herrera
- Centro de Investigación en Alimentación y Desarrollo A.C., (CIAD) Unidad Mazatlán, Av. Sábalo-Cerritos S/N. Col. Estero del Yugo, C.P. 82000 Mazatlán, Sinaloa, Mexico; CONACYT, Consejo Nacional de Ciencia y Tecnología, Av. Insurgentes Sur 1582, Ciudad de México 03940, Mexico
| | - Ana M Ibarra
- Centro de Investigaciones Biológicas del Noroeste, S.C. (CIBNOR). Programa de Acuacultura, Av. Instituto Politécnico Nacional No. 195, Col. Playa Palo de Santa Rita, La Paz, Baja California Sur C.P. 23096, Mexico.
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Drosopoulou E, Pantelidou C, Gariou-Papalexiou A, Augustinos AA, Chartomatsidou T, Kyritsis GA, Bourtzis K, Mavragani-Tsipidou P, Zacharopoulou A. The chromosomes and the mitogenome of Ceratitis fasciventris (Diptera: Tephritidae): two genetic approaches towards the Ceratitis FAR species complex resolution. Sci Rep 2017; 7:4877. [PMID: 28687799 PMCID: PMC5501848 DOI: 10.1038/s41598-017-05132-3] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2017] [Accepted: 05/25/2017] [Indexed: 11/29/2022] Open
Abstract
Ceratitis fasciventris is a serious agricultural pest of the Tephritidae family that belongs to the African Ceratitis FAR species complex. Species limits within the FAR complex are obscure and multidisciplinary approaches have attempted to resolve phylogenetic relationships among its members. These studies support the existence of at least three additional species in the complex, C. anonnae, C. rosa and C. quilicii, while they indicate the presence of two structured populations (F1 and F2) within the C. fasciventris species. In the present study we present the mitotic karyotype, polytene chromosome maps, in situ hybridization data and the complete mitochondrial genome sequence of an F2 population of C. fasciventris. This is the first polytene chromosome map and complete mitogenome of a member of the FAR complex and only the second reported for the Ceratitis genus. Both polytene chromosomes and mitochondrial sequence could provide valuable information and be used as reference for comparative analysis among the members of the complex towards the clarification of their phylogenetic relationships.
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Affiliation(s)
- Elena Drosopoulou
- Department of Genetics, Development and Molecular Biology, School of Biology, Faculty of Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece.
| | - Christina Pantelidou
- Department of Genetics, Development and Molecular Biology, School of Biology, Faculty of Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | | | - Antonios A Augustinos
- Department of Biology, University of Patras, Patras, Greece.,Insect Pest Control Laboratory, Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, Seibersdorf, Vienna, Austria
| | - Tatiana Chartomatsidou
- Department of Genetics, Development and Molecular Biology, School of Biology, Faculty of Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece
| | - Georgios A Kyritsis
- Insect Pest Control Laboratory, Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, Seibersdorf, Vienna, Austria
| | - Kostas Bourtzis
- Insect Pest Control Laboratory, Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, Seibersdorf, Vienna, Austria
| | - Penelope Mavragani-Tsipidou
- Department of Genetics, Development and Molecular Biology, School of Biology, Faculty of Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece
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Sawanth SK, Gopinath G, Sambrani N, Arunkumar KP. The autoregulatory loop: A common mechanism of regulation of key sex determining genes in insects. J Biosci 2017; 41:283-94. [PMID: 27240989 DOI: 10.1007/s12038-016-9609-x] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Sex determination in most insects is structured as a gene cascade, wherein a primary signal is passed through a series of sex-determining genes, culminating in a downstream double-switch known as doublesex that decides the sexual fate of the embryo. From the literature available on sex determination cascades, it becomes apparent that sex determination mechanisms have evolved rapidly. The primary signal that provides the cue to determine the sex of the embryo varies remarkably, not only among taxa, but also within taxa. Furthermore, the upstream key gene in the cascade also varies between species and even among closely related species. The order Insecta alone provides examples of astoundingly complex diversity of upstream key genes in sex determination mechanisms. Besides, unlike key upstream genes, the downstream double-switch gene is alternatively spliced to form functional sex-specific isoforms. This sex-specific splicing is conserved across insect taxa. The genes involved in the sex determination cascade such as Sex-lethal (Sxl) in Drosophila melanogaster, transformer (tra) in many other dipterans, coleopterans and hymenopterans, Feminizer (fem) in Apis mellifera, and IGF-II mRNA-binding protein (Bmimp) in Bombyx mori are reported to be regulated by an autoregulatory positive feedback loop. In this review, by taking examples from various insects, we propose the hypothesis that autoregulatory loop mechanisms of sex determination might be a general strategy. We also discuss the possible reasons for the evolution of autoregulatory loops in sex determination cascades and their impact on binary developmental choices.
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Affiliation(s)
- Suresh Kumar Sawanth
- Centre of Excellence for Genetics and Genomics of Silkmoths, Laboratory of Molecular Genetics, Centre for DNA Fingerprinting and Diagnostics, Hyderabad 500 001, India
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Huang CY, Dai SM, Chang C. Introduction of the RTA-Bddsx gene induces female-specific lethal effects in transformed Bactrocera dorsalis (Hendel). PEST MANAGEMENT SCIENCE 2016; 72:1160-1167. [PMID: 26269247 DOI: 10.1002/ps.4094] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/16/2015] [Revised: 07/24/2015] [Accepted: 08/10/2015] [Indexed: 06/04/2023]
Abstract
BACKGROUND The oriental fruit fly, Bactrocera dorsalis (Hendel), can reduce fruit production and quality and is considered to be a major insect pest in many Asian countries. A system combining the toxicity of ricin and the alternative RNA splicing properties of doublesex (RTA-Bddsx) has been proposed that results in differential sexual processing in vitro. A transgenic approach was used in this study to confirm the existence of female-specific lethal effects in vivo. RESULTS The piggyBac-based vector PB-Acp-CF21-26, which carries the actin 5C promoter and RTA-Bddsx, was used to establish transgenic lines. Five surviving male flies (F1) demonstrated the presence of selection marker Ds-Red((+)) throughout their entire bodies following single-pair mating with wild-type females, indicating germline transmission. A high percentage of males (59.6-100%) were observed in transformed F3 offspring, and this skewed sex ratio indicated that the female-lethal effects of the RTA-Bddsx system were heritable and functioned well in B. dorsalis. Some transformed female flies were observed, and these unexpected results were attributed to the loss of the intact transgene after genomic PCR analyses. CONCLUSION This transgenic study provides direct evidence for the female-specific lethal effects of RTA-Bddsx in B. dorsalis and offers a novel and promising approach for the control of B. dorsalis in the future. © 2015 Society of Chemical Industry.
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Affiliation(s)
- Chun-Yen Huang
- Biotechnology Centre, National Chung-Hsing University, Taichung, Taiwan
| | - Shu-Mei Dai
- Department of Entomology, National Chung-Hsing University, Taichung, Taiwan
| | - Cheng Chang
- Biotechnology Centre, National Chung-Hsing University, Taichung, Taiwan
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15
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Huang CY, Huang CC, Dai SM, Chang C. Establishment of an RTA-Bddsx hybrid system for female-specific splicing that can affect the sex ratio of Bactrocera dorsalis (Hendel) after embryonic injection. PEST MANAGEMENT SCIENCE 2016; 72:280-288. [PMID: 25656748 DOI: 10.1002/ps.3990] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Revised: 02/02/2015] [Accepted: 02/02/2015] [Indexed: 06/04/2023]
Abstract
BACKGROUND The oriental fruit fly, Bactrocera dorsalis (Hendel), a very destructive insect pest in many areas of Asia, including Taiwan, can cause significant damage by ovipositing in and larval feeding on many kinds of fruit. A female lethal system, combining the splicing property of doublesex (dsx) with the toxicity of ricin A chain (RTA), has been developed. In this system, a modified RTA is separated by Bddsx intron 3; the expressed RNA can only be spliced in females, with toxic effects, whereas the immature RTA in males is harmless. RESULTS Two RTA-Bddsx constructs, clone BE 24-7 and clone CF 26-21, containing Bddsx intron 3 and its flanking exonic sequences, with four nucleotides at the 5'-end and five nucleotides at the 3'-end, correctly spliced in a sex-specific manner. Wild-type and modified RTAs expressed in an Escherichia coli system retained their ability to suppress protein synthesis: 90.4% for Ricin-WT, 71.3% for Ricin-LERQ and 58.0% for Ricin-FEGQ. Embryonic injection of Acp-CF26-21, the RTA-Bddsx gene driven by the actin 5C promoter, resulted in a significant increase in male percentage in the eclosed adults. CONCLUSION Our results indicate that the RTA-Bddsx hybrid system offers a novel and promising approach for oriental fruit fly control.
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Affiliation(s)
- Chun-Yen Huang
- Biotechnology Centre, National Chung-Hsing University, Taichung, Taiwan
| | - Chia Chia Huang
- Biotechnology Centre, National Chung-Hsing University, Taichung, Taiwan
| | - Shu-Mei Dai
- Department of Entomology, National Chung-Hsing University, Taichung, Taiwan
| | - Cheng Chang
- Biotechnology Centre, National Chung-Hsing University, Taichung, Taiwan
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Laohakieat K, Aketarawong N, Isasawin S, Thitamadee S, Thanaphum S. The study of the transformer gene from Bactrocera dorsalis and B. correcta with putative core promoter regions. BMC Genet 2016; 17:34. [PMID: 26833079 PMCID: PMC4736151 DOI: 10.1186/s12863-016-0342-0] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Accepted: 01/25/2016] [Indexed: 12/31/2022] Open
Abstract
Background The transformer (tra) is a sex determining switch in different orders of insects, including Diptera, as in the family Tephritidae. The lifelong autoregulatory loop of tra female-specific splicing can be reset by the intervention of male-specific primary signals (M factor). In early development, the functional female and truncated male TRA proteins relay the sexual fates to the alternative splicing of a bisexual switch gene, doublesex (dsx) cascading the sexual differentiation processes. Bactrocera dorsalis (Hendel) and Bactrocera correcta (Bezzi) are among the Bactrocera model worldwide key pests. Area-wide integrated pest management using the male-only Sterile Insect Technique (SIT) relying on genetic sexing systems is effective in control programs. We undertook the molecular characterization and comparative studies of the tra orthologues in the Bactrocera species, including the Salaya1 genetic sexing strain (GSS). Results RT-PCR revealed that B. dorsalis tra (Bdtra) and B. correcta tra (Bctra) transcripts contained conservation of both constitutive exons and male-specific exons as in other Bactrocera. However, new Bdtra male-specific exons were retained, diversifying the pattern of the male-specifically spliced transcripts. The coding sequences of tra were highly conserved in Bactrocera (86–95 %) but less so among related genera (61–65 %) within the same Tephritidae family. A conservation of deduced amino acid sequences (18 residues), called the TEP region, was identified to be distinctive among tephritids. The 5’ regulatory sequence containing many structural characteristics of the putative core promoter was discovered in B. correcta. The expression patterns of Bdtra and Bctra were sex-specifically spliced and the signals relayed to the dsx genes in the adult wild-types. However, the coexistence of male- and female-specifically spliced transcripts (980 and 626 bp, respectively) of the B. dorsalis wild-type strain was found in the Salaya1 GSS adult males. The Bdtra RNA interference masculinized the XX karyotype females into pseudomales, but their testes were mostly not well developed. Conclusions Bdtra and Bctra have sex-specific splicing, similar to Bactroceras, Ceratitis capitata (Wiedemann), and Anastrephas. A newly identified TEP region is proposed in tephritids. A putative core promoter has been discovered in Bctra. Electronic supplementary material The online version of this article (doi:10.1186/s12863-016-0342-0) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Kamoltip Laohakieat
- Department of Biotechnology, Faculty of Science, Mahidol University, Rama VI Road, Bangkok, 10400, Thailand.
| | - Nidchaya Aketarawong
- Department of Biotechnology, Faculty of Science, Mahidol University, Rama VI Road, Bangkok, 10400, Thailand.
| | - Siriwan Isasawin
- Department of Biotechnology, Faculty of Science, Mahidol University, Rama VI Road, Bangkok, 10400, Thailand.
| | - Siripong Thitamadee
- Department of Biotechnology, Faculty of Science, Mahidol University, Rama VI Road, Bangkok, 10400, Thailand.
| | - Sujinda Thanaphum
- Department of Biotechnology, Faculty of Science, Mahidol University, Rama VI Road, Bangkok, 10400, Thailand.
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Tsoumani KT, Drosopoulou E, Bourtzis K, Gariou-Papalexiou A, Mavragani-Tsipidou P, Zacharopoulou A, Mathiopoulos KD. Achilles, a New Family of Transcriptionally Active Retrotransposons from the Olive Fruit Fly, with Y Chromosome Preferential Distribution. PLoS One 2015; 10:e0137050. [PMID: 26398504 PMCID: PMC4580426 DOI: 10.1371/journal.pone.0137050] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2015] [Accepted: 08/13/2015] [Indexed: 11/19/2022] Open
Abstract
Sex chromosomes have many unusual features relative to autosomes. The in depth exploration of their structure will improve our understanding of their origin and divergence (degeneration) as well as the evolution of genetic sex determination pathways which, most often are attributed to them. In Tephritids, the structure of Y chromosome, where the male-determining factor M is localized, is largely unexplored and limited data concerning its sequence content and evolution are available. In order to get insight into the structure and organization of the Y chromosome of the major olive insect pest, the olive fly Bactrocera oleae, we characterized sequences from a Pulse Field Gel Electrophoresis (PFGE)-isolated Y chromosome. Here, we report the discovery of the first olive fly LTR retrotransposon with increased presence on the Y chromosome. The element belongs to the BEL-Pao superfamily, however, its sequence comparison with the other members of the superfamily suggests that it constitutes a new family that we termed Achilles. Its ~7.5 kb sequence consists of the 5'LTR, the 5'non-coding sequence and the open reading frame (ORF), which encodes the polyprotein Gag-Pol. In situ hybridization to the B. oleae polytene chromosomes showed that Achilles is distributed in discrete bands dispersed on all five autosomes, in all centromeric regions and in the granular heterochromatic network corresponding to the mitotic sex chromosomes. The between sexes comparison revealed a variation in Achilles copy number, with male flies possessing 5-10 copies more than female (CI range: 18-38 and 12-33 copies respectively per genome). The examination of its transcriptional activity demonstrated the presence of at least one intact active copy in the genome, showing a differential level of expression between sexes as well as during embryonic development. The higher expression was detected in male germline tissues (testes). Moreover, the presence of Achilles-like elements in different species of the Tephritidae family suggests an ancient origin of this element.
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Affiliation(s)
| | - Elena Drosopoulou
- Department of Genetics, Development and Molecular Biology, Aristotle University of Thessaloniki (AUTH), Thessaloniki, Greece
| | - Kostas Bourtzis
- Insect Molecular Genetics Group, IMBB, Vassilika Vouton, 71110 Heraklion, Crete, PO Box 1527, Greece
- Department of Environmental and Natural Resources Management, University of Patras, Agrinio, Greece
- Insect Pest Control Laboratory, Joint FAO/IAEA Division of Nuclear Techniques in Food and Agriculture, Vienna, Austria
| | - Aggeliki Gariou-Papalexiou
- Department of Biology, Division of Genetics, Cell and Developmental Biology, University of Patras, Patras, Greece
| | - Penelope Mavragani-Tsipidou
- Department of Genetics, Development and Molecular Biology, Aristotle University of Thessaloniki (AUTH), Thessaloniki, Greece
| | - Antigone Zacharopoulou
- Department of Biology, Division of Genetics, Cell and Developmental Biology, University of Patras, Patras, Greece
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18
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Price DC, Egizi A, Fonseca DM. Characterization of the doublesex gene within the Culex pipiens complex suggests regulatory plasticity at the base of the mosquito sex determination cascade. BMC Evol Biol 2015; 15:108. [PMID: 26058583 PMCID: PMC4461909 DOI: 10.1186/s12862-015-0386-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2014] [Accepted: 05/22/2015] [Indexed: 11/25/2022] Open
Abstract
Background The doublesex gene controls somatic sexual differentiation of many metazoan species, including the malaria mosquito Anopheles gambiae and the dengue and yellow fever vector Aedes aegypti (Diptera: Culicidae). As in other studied dipteran dsx homologs, the gene maintains functionality via evolutionarily conserved protein domains and sex-specific alternative splicing. The upstream factors that regulate splicing of dsx and the manner in which they do so however remain variable even among closely related organisms. As the induction of sex ratio biases is a central mode of action in many emerging molecular insecticides, it is imperative to elucidate as much of the sex determination pathway as possible in the mosquito disease vectors. Results Here we report the full-length gene sequence of the doublesex gene in Culex quinquefasciatus (Cxqdsx) and its male and female-specific isoforms. Cxqdsx maintains characteristics possibly derived in the Culicinae and present in the Aedes aegypti dsx gene (Aeadsx) such as gain of exon 3b and the presence of Rbp1 cis-regulatory binding sites, and also retains presumably ancestral attributes present in Anopheles gambiae such as maintenance of a singular female-specific exon 5. Unlike in Aedes aegypti, we find no evidence for intron gain in the female transcript(s), yet recover a second female isoform generated via selection of an alternate splice donor. Utilizing next-gen sequence (NGS) data, we complete the Aeadsx gene model and identify a putative core promoter region in both Aeadsx and Cxqdsx. Also utilizing NGS data, we construct a full-length gene sequence for the dsx homolog of the northern house mosquito Culex pipiens form pipiens (Cxpipdsx). Analysis of peptide evolutionary rates between Cxqdsx and Cxpipdsx (both members of the Culex pipiens complex) shows the male-specific portion of the transcript to have evolved rapidly with respect to female-specific and common regions. Conclusions As in other studied insects, doublesex maintains sex-specific splicing and conserved doublesex/mab-3 domains in the mosquitoes Culex quinquefasciatus and Cx. pipiens. The cis-regulated splicing of Cxqdsx does not appear to follow either currently described mosquito model (for An. gambiae and Ae. aegypti); each of the three mosquito genera exhibit evidence of unique cis-regulatory mechanisms. The male-specific dsx terminus exhibits rapid peptide evolutionary rates, even among closely related sibling species. Electronic supplementary material The online version of this article (doi:10.1186/s12862-015-0386-1) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Dana C Price
- Department of Entomology, Rutgers University, 178 Jones Avenue, New Brunswick, NJ, 08901, USA.
| | - Andrea Egizi
- Department of Entomology, Rutgers University, 178 Jones Avenue, New Brunswick, NJ, 08901, USA. .,Graduate Program in Ecology and Evolution, Rutgers University, New Brunswick, NJ, USA.
| | - Dina M Fonseca
- Department of Entomology, Rutgers University, 178 Jones Avenue, New Brunswick, NJ, 08901, USA.
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An Unusual Role for doublesex in Sex Determination in the Dipteran Sciara. Genetics 2015; 200:1181-99. [PMID: 26063659 DOI: 10.1534/genetics.115.177972] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2015] [Accepted: 06/04/2015] [Indexed: 11/18/2022] Open
Abstract
The gene doublesex, which is placed at the bottom of the sex-determination gene cascade, plays the ultimate discriminatory role for sex determination in insects. In all insects where this gene has been characterized, the dsx premessenger RNA (pre-mRNA) follows a sex-specific splicing pattern, producing male- and female-specific mRNAs encoding the male-DSXM and female-DSXF proteins, which determine male and female development, respectively. This article reports the isolation and characterization of the gene doublesex of dipteran Sciara insects. The Sciara doublesex gene is constitutively transcribed during development and adult life of males and females. Sciara had no sex-specific doublesex mRNAs but the same transcripts, produced by alternative splicing of its primary transcript, were present in both sexes, although their relative abundance is sex specific. However, only the female DSXF protein, but not the male DSXM protein, was produced at similar amounts in both sexes. An analysis of the expression of female and male Sciara DSX proteins in Drosophila showed that these proteins conserved female and male function, respectively, on the control of Drosophila yolk-protein genes. The molecular evolution of gene doublesex of all insects where this gene has been characterized revealed that Sciara doublesex displays a considerable degree of divergence in its molecular organization and its splicing pattern with respect to the rest of dipterans as suggested by its basal position within the doublesex phylogeny. It is suggested that the doublesex gene is involved in Sciara sex determination although it appears not to play the discriminatory role performed in other insects.
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20
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Verhulst EC, van de Zande L. Double nexus--Doublesex is the connecting element in sex determination. Brief Funct Genomics 2015; 14:396-406. [PMID: 25797692 PMCID: PMC4652034 DOI: 10.1093/bfgp/elv005] [Citation(s) in RCA: 59] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
In recent years, our knowledge of the conserved master-switch gene doublesex (dsx) and its function in regulating the development of dimorphic traits in insects has deepened considerably. Here, a comprehensive overview is given on the properties of the male- and female-specific dsx transcripts yielding DSXF and DSXM proteins in Drosophila melanogaster, and the many downstream targets that they regulate. As insects have cell-autonomous sex determination, it was assumed that dsx would be expressed in every somatic cell, but recent research showed that dsx is expressed only when a cell is required to show its sexual identity through function or morphology. This spatiotemporal regulation of dsx expression has not only been established in D. melanogaster but in all insect species studied. Gradually, it has been appreciated that dsx could no longer be viewed as the master-switch gene orchestrating sexual development and behaviour in each cell, but instead should be viewed as the interpreter for the sexual identity of the cell, expressing this identity only on request, making dsx the central nexus of insect sex determination.
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21
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Drosopoulou E, Nakou I, Mavragani-Tsipidou P. The Bactrocera oleae genome: localization of nine genes on the polytene chromosomes of the olive fruit fly (Diptera: Tephritidae). Genome 2015; 57:573-6. [PMID: 25723592 DOI: 10.1139/gen-2014-0172] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Four homologous and five heterologous gene-specific sequences have been mapped by in situ hybridization on the salivary gland polytene chromosomes of the olive fruit fly, Bactrocera oleae. The nine genes were dispersed on four of the five autosomal chromosomes, thus enriching the available set of chromosome landmarks for this major agricultural pest. Present data further supports the proposed chromosome homologies among B. oleae, Ceratitis capitata, and Drosophila melanogaster and the idea of the conservation of chromosomal element identity throughout dipteran evolution.
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Affiliation(s)
- Elena Drosopoulou
- Department of Genetics, Development and Molecular Biology, School of Biology, Faculty of Sciences, Aristotle University of Thessaloniki (AUTH), GR-54124, Thessaloniki, Greece
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22
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Morrow JL, Riegler M, Gilchrist AS, Shearman DCA, Frommer M. Comprehensive transcriptome analysis of early male and female Bactrocera jarvisi embryos. BMC Genet 2014; 15 Suppl 2:S7. [PMID: 25472807 PMCID: PMC4255828 DOI: 10.1186/1471-2156-15-s2-s7] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022] Open
Abstract
Background Developing embryos are provided with maternal RNA transcripts and proteins, but transcription from the zygotic nuclei must be activated to control continuing embryonic development. Transcripts are generated at different stages of early development, and those involved in sex determination and cellularisation are some of the earliest to be activated. The male sex in tephritid fruit flies is determined by the presence of a Y chromosome, and it is believed that a transcript from the Y-chromosome sets in motion a cascade that determines male development, as part of the greater maternal to zygotic transition (MTZ). Here we investigate the poly(A+) transcriptome in early male and female embryos of the horticultural pest Bactrocera jarvisi (Diptera: Tephritidae). Results Bactrocera jarvisi embryos were collected over two pre-blastoderm time periods, 2-3h and 3-5h after egg laying. Embryos were individually sexed using a Y-chromosome marker, allowing the sex-specific poly(A+) transcriptome of single-sex embryo pools to be deep-sequenced and assembled de novo. Transcripts for sixteen sex-determination and two cellularisation gene homologues of Drosophila melanogaster (Diptera: Drosophilidae) were identified in early embryos of B. jarvisi, including transcripts highly upregulated prior to cellularisation. No strong candidates for transcripts derived solely from the Y chromosome were recovered from the poly(A+) fraction. Conclusions Bactrocera jarvisi provides an excellent model for embryonic studies due to available Y-chromosome markers and the compact time frame for zygotic transcription and the sex-determined state. Our data contribute fundamental information to sex-determination research, and provide candidates for the sourcing of gene promoters for transgenic pest-management strategies of tephritid fruit flies.
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Sagri E, Reczko M, Tsoumani KT, Gregoriou ME, Harokopos V, Mavridou AM, Tastsoglou S, Athanasiadis K, Ragoussis J, Mathiopoulos KD. The molecular biology of the olive fly comes of age. BMC Genet 2014; 15 Suppl 2:S8. [PMID: 25472866 PMCID: PMC4255830 DOI: 10.1186/1471-2156-15-s2-s8] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022] Open
Abstract
Background Olive cultivation blends with the history of the Mediterranean countries since ancient times. Even today, activities around the olive tree constitute major engagements of several people in the countryside of both sides of the Mediterranean basin. The olive fly is, beyond doubt, the most destructive pest of cultivated olives. The female fly leaves its eggs in the olive fruit. Upon emergence, the larvae feed on the olive sap, thus destroying the fruit. If untreated, practically all olives get infected. The use of chemical insecticides constitutes the principal olive fly control approach. The Sterile Insect Technique (SIT), an environmentally friendly alternative control method, had been tried in pilot field applications in the 1970's, albeit with no practical success. This was mainly attributed to the low, non-antagonistic quality of the mixed-sex released insects. Many years of experience from successful SIT applications in related species, primarily the Mediterranean fruit fly, Ceratitis capitata, demonstrated that efficient SIT protocols require the availability of fundamental genetic and molecular information. Results Among the primary systems whose understanding can contribute towards novel SIT approaches (or its recently developed alternative RIDL: Release of Insects carrying a Dominant Lethal) is the reproductive, since the ability to manipulate the reproductive system would directly affect the insect's fertility. In addition, the analysis of early embryonic promoters and apoptotic genes would provide tools that confer dominant early-embryonic lethality during mass-rearing. Here we report the identification of several genes involved in these systems through whole transcriptome analysis of female accessory glands (FAGs) and spermathecae, as well as male testes. Indeed, analysis of differentially expressed genes in these tissues revealed higher metabolic activity in testes than in FAGs/spermathecae. Furthermore, at least five olfactory-related genes were shown to be differentially expressed in the female and male reproductive systems analyzed. Finally, the expression profile of the embryonic serendipity-α locus and the pre-apoptotic head involution defective gene were analyzed during embryonic developmental stages. Conclusions Several years of molecular studies on the olive fly can now be combined with new information from whole transcriptome analyses and lead to a deep understanding of the biology of this notorious insect pest. This is a prerequisite for the development of novel embryonic lethality female sexing strains for successful SIT efforts which, combined with improved mass-reared conditions, give new hope for efficient SIT applications for the olive fly.
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Augustinos AA, Drosopoulou E, Gariou-Papalexiou A, Bourtzis K, Mavragani-Tsipidou P, Zacharopoulou A. The Bactrocera dorsalis species complex: comparative cytogenetic analysis in support of Sterile Insect Technique applications. BMC Genet 2014; 15 Suppl 2:S16. [PMID: 25471636 PMCID: PMC4255788 DOI: 10.1186/1471-2156-15-s2-s16] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/09/2023] Open
Abstract
Background The Bactrocera dorsalis species complex currently harbors approximately 90 different members. The species complex has undergone many revisions in the past decades, and there is still an ongoing debate about the species limits. The availability of a variety of tools and approaches, such as molecular-genomic and cytogenetic analyses, are expected to shed light on the rather complicated issues of species complexes and incipient speciation. The clarification of genetic relationships among the different members of this complex is a prerequisite for the rational application of sterile insect technique (SIT) approaches for population control. Results Colonies established in the Insect Pest Control Laboratory (IPCL) (Seibersdorf, Vienna), representing five of the main economic important members of the Bactrocera dorsalis complex were cytologically characterized. The taxa under study were B. dorsalis s.s., B. philippinensis, B. papayae, B. invadens and B. carambolae. Mitotic and polytene chromosome analyses did not reveal any chromosomal characteristics that could be used to distinguish between the investigated members of the B. dorsalis complex. Therefore, their polytene chromosomes can be regarded as homosequential with the reference maps of B. dorsalis s.s.. In situ hybridization of six genes further supported the proposed homosequentiallity of the chromosomes of these specific members of the complex. Conclusions The present analysis supports that the polytene chromosomes of the five taxa under study are homosequential. Therefore, the use of the available polytene chromosome maps for B. dorsalis s.s. as reference maps for all these five biological entities is proposed. Present data provide important insight in the genetic relationships among the different members of the B. dorsalis complex, and, along with other studies in the field, can facilitate SIT applications targeting this complex. Moreover, the availability of 'universal' reference polytene chromosome maps for members of the complex, along with the documented application of in situ hybridization, can facilitate ongoing and future genome projects in this complex.
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Morrow JL, Riegler M, Frommer M, Shearman DCA. Expression patterns of sex-determination genes in single male and female embryos of two Bactrocera fruit fly species during early development. INSECT MOLECULAR BIOLOGY 2014; 23:754-767. [PMID: 25116961 DOI: 10.1111/imb.12123] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
In tephritids, the sex-determination pathway follows the sex-specific splicing of transformer (tra) mRNA, and the cooperation of tra and transformer-2 (tra-2) to effect the sex-specific splicing of doublesex (dsx), the genetic double-switch responsible for male or female somatic development. The Dominant Male Determiner (M) is the primary signal that controls this pathway. M, as yet uncharacterized, is Y-chromosome linked, expressed in the zygote and directly or indirectly diminishes active TRA protein in male embryos. Here we first demonstrated the high conservation of tra, tra-2 and dsx in two Australian tephritids, Bactrocera tryoni and Bactrocera jarvisi. We then used quantitative reverse transcription PCR on single, sexed embryos to examine expression of the key sex-determination genes during early embryogenesis. Individual embryos were sexed using molecular markers located on the B. jarvisi Y-chromosome that was also introgressed into a B. tryoni line. In B. jarvisi, sex-specific expression of tra transcripts occurred between 3 to 6 h after egg laying, and the dsx isoform was established by 7 h. These milestones were delayed in B. tryoni lines. The results provide a time frame for transcriptomic analyses to identify M and its direct targets, plus information on genes that may be targeted for the development of male-only lines for pest management.
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Affiliation(s)
- J L Morrow
- Hawkesbury Institute for the Environment, University of Western Sydney, Penrith, NSW, Australia
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Xu SL, Zhou W, Chen P, Zhou JK, Zou X, Wang CL, Wang DL, Zhao YL. Identification and expression analysis of a doublesex1 gene in Daphnia pulex during different reproductive stages. Dev Genes Evol 2014; 224:147-57. [DOI: 10.1007/s00427-014-0472-1] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/08/2014] [Accepted: 05/13/2014] [Indexed: 11/29/2022]
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Geuverink E, Beukeboom LW. Phylogenetic distribution and evolutionary dynamics of the sex determination genes doublesex and transformer in insects. Sex Dev 2013; 8:38-49. [PMID: 24401160 DOI: 10.1159/000357056] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Sex determination in insects is characterized by a gene cascade that is conserved at the bottom but contains diverse primary signals at the top. The bottom master switch gene doublesex is found in all insects. Its upstream regulator transformer is present in the orders Hymenoptera, Coleoptera and Diptera, but has thus far not been found in Lepidoptera and in the basal lineages of Diptera. transformer is presumed to be ancestral to the holometabolous insects based on its shared domains and conserved features of autoregulation and sex-specific splicing. We interpret that its absence in basal lineages of Diptera and its order-specific conserved domains indicate multiple independent losses or recruitments into the sex determination cascade. Duplications of transformer are found in derived families within the Hymenoptera, characterized by their complementary sex determination mechanism. As duplications are not found in any other insect order, they appear linked to the haplodiploid reproduction of the Hymenoptera. Further phylogenetic analyses combined with functional studies are needed to understand the evolutionary history of the transformer gene among insects.
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Affiliation(s)
- E Geuverink
- Evolutionary Genetics, Center for Ecological and Evolutionary Studies, University of Groningen, Groningen, The Netherlands
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Shukla JN, Palli SR. Tribolium castaneum Transformer-2 regulates sex determination and development in both males and females. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2013; 43:1125-32. [PMID: 24056158 PMCID: PMC3965185 DOI: 10.1016/j.ibmb.2013.08.010] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2013] [Revised: 08/23/2013] [Accepted: 08/29/2013] [Indexed: 05/24/2023]
Abstract
Tribolium castaneum Transformer (TcTra) is essential for female sex determination and maintenance through the regulation of sex-specific splicing of doublesex (dsx) pre-mRNA. In females, TcTra also regulates the sex-specific splicing of its own pre-mRNA to ensure continuous production of functional Tra protein. Transformer protein is absent in males and hence dsx pre-mRNA is spliced in a default mode. The mechanisms by which males inhibit the production of functional Tra protein are not known. Here, we report on functional characterization of transformer-2 (tra-2) gene (an ortholog of Drosophila transformer-2) in T. castaneum. RNA interference-mediated knockdown in the expression of gene coding for tra-2 in female pupae or adults resulted in the production of male-specific isoform of dsx and both female and male isoforms of tra suggesting that Tra-2 is essential for the female-specific splicing of tra and dsx pre-mRNAs. Interestingly, knockdown of tra-2 in males did not affect the splicing of dsx but resulted in the production of both female and male isoforms of tra suggesting that Tra-2 suppresses female-specific splicing of tra pre-mRNA in males. This dual regulation of sex-specific splicing of tra pre-mRNA ensures a tight regulation of sex determination and maintenance. These data suggest a critical role for Tra-2 in suppression of female sex determination cascade in males. In addition, RNAi studies showed that Tra-2 is also required for successful embryonic and larval development in both sexes.
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Affiliation(s)
| | - Subba Reddy Palli
- Corresponding author. Tel.: +1 859 257 4962; fax: +1 859 323 1120. , (S.R. Palli)
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Tsoumani KT, Drosopoulou E, Mavragani-Tsipidou P, Mathiopoulos KD. Molecular characterization and chromosomal distribution of a species-specific transcribed centromeric satellite repeat from the olive fruit fly, Bactrocera oleae. PLoS One 2013; 8:e79393. [PMID: 24244494 PMCID: PMC3828357 DOI: 10.1371/journal.pone.0079393] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2013] [Accepted: 09/30/2013] [Indexed: 11/19/2022] Open
Abstract
Satellite repetitive sequences that accumulate in the heterochromatin consist a large fraction of a genome and due to their properties are suggested to be implicated in centromere function. Current knowledge of heterochromatic regions of Bactrocera oleae genome, the major pest of the olive tree, is practically nonexistent. In our effort to explore the repetitive DNA portion of B. oleae genome, a novel satellite sequence designated BoR300 was isolated and cloned. The present study describes the genomic organization, abundance and chromosomal distribution of BoR300 which is organized in tandem, forming arrays of 298 bp-long monomers. Sequence analysis showed an AT content of 60.4%, a CENP-B like-motif and a high curvature value based on predictive models. Comparative analysis among randomly selected monomers demonstrated a high degree of sequence homogeneity (88%-97%) of BoR300 repeats, which are present at approximately 3,000 copies per haploid genome accounting for about 0.28% of the total genomic DNA, based on two independent qPCR approaches. In addition, expression of the repeat was also confirmed through RT-PCR, by which BoR300 transcripts were detected in both sexes. Fluorescence in situ hybridization (FISH) of BoR300 on mitotic metaphases and polytene chromosomes revealed signals to the centromeres of two out of the six chromosomes which indicated a chromosome-specific centromeric localization. Moreover, BoR300 is not conserved in the closely related Bactrocera species tested and it is also absent in other dipterans, but it's rather restricted to the B. oleae genome. This feature of species-specificity attributed to BoR300 satellite makes it a good candidate as an identification probe of the insect among its relatives at early development stages.
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Affiliation(s)
| | - Elena Drosopoulou
- Department of Genetics, Development and Molecular Biology, Aristotle University of Thessaloniki (AUTH), Thessaloniki, Greece
| | - Penelope Mavragani-Tsipidou
- Department of Genetics, Development and Molecular Biology, Aristotle University of Thessaloniki (AUTH), Thessaloniki, Greece
| | - Kostas D. Mathiopoulos
- Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Greece
- * E-mail:
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Male-specific splicing of the silkworm Imp gene is maintained by an autoregulatory mechanism. Mech Dev 2013; 131:47-56. [PMID: 24231282 DOI: 10.1016/j.mod.2013.10.004] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2013] [Revised: 10/18/2013] [Accepted: 10/29/2013] [Indexed: 11/24/2022]
Abstract
Sexual differentiation in the silkworm Bombyx mori is controlled by sex-specific splicing of Bmdsx, in which exons 3 and 4 are skipped in males. B. mori insulin-like growth factor II mRNA-binding protein (Imp) is a factor involved in the male-specific splicing of Bmdsx. In this study, we found that the male-specific Imp mRNA is formed as a result of the inclusion of exon 8 and the promoter-distal poly(A) site choice, whereas non-sex-specific polyadenylation occurs at the promoter-proximal poly(A) site downstream of exon 7. Recent studies revealed that Drosophila Sxl, tra in several dipteran and hymenopteran insects, and fem in Apis mellifera, play a central role in sex determination and maintain their productive mode of expression via an autoregulatory function. To determine whether Imp protein is required for the maintenance of the male-specific splicing of its own pre-mRNA, we knocked down endogenous Imp in male cells and assessed the male-specific splicing of an exogenous Imp minigene. Knockdown of endogenous Imp inhibited the male-specific splicing of the Imp minigene transcript. In contrast, overexpression of Imp in female cells induced the male-specific splicing of the Imp minigene transcript. Moreover, deletion of adenine-rich (A-rich) sequences located downstream of the proximal poly(A) site repressed the male-specific splicing of the Imp minigene transcript. Finally, gel shift analysis demonstrated that Imp binds to the A-rich sequences. These data suggest that Imp binds to the A-rich sequences in its own pre-mRNA to induce the male-specific splicing of its pre-mRNA.
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Ruiz MF, Sarno F, Zorrilla S, Rivas G, Sánchez L. Biochemical and functional analysis of Drosophila-sciara chimeric sex-lethal proteins. PLoS One 2013; 8:e65171. [PMID: 23762307 PMCID: PMC3677924 DOI: 10.1371/journal.pone.0065171] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/27/2013] [Accepted: 04/21/2013] [Indexed: 12/31/2022] Open
Abstract
BACKGROUND The Drosophila SXL protein controls sex determination and dosage compensation. It is a sex-specific factor controlling splicing of its own Sxl pre-mRNA (auto-regulation), tra pre-mRNA (sex determination) and msl-2 pre-mRNA plus translation of msl-2 mRNA (dosage compensation). Outside the drosophilids, the same SXL protein has been found in both sexes so that, in the non-drosophilids, SXL does not appear to play the key discriminating role in sex determination and dosage compensation that it plays in Drosophila. Comparison of SXL proteins revealed that its spatial organisation is conserved, with the RNA-binding domains being highly conserved, whereas the N- and C-terminal domains showing significant variation. This manuscript focuses on the evolution of the SXL protein itself and not on regulation of its expression. METHODOLOGY Drosophila-Sciara chimeric SXL proteins were produced. Sciara SXL represents the non-sex-specific function of ancient SXL in the non-drosophilids from which presumably Drosophila SXL evolved. Two questions were addressed. Did the Drosophila SXL protein have affected their functions when their N- and C-terminal domains were replaced by the corresponding ones of Sciara? Did the Sciara SXL protein acquire Drosophila sex-specific functions when the Drosophila N- and C-terminal domains replaced those of Sciara? The chimeric SXL proteins were analysed in vitro to study their binding affinity and cooperative properties, and in vivo to analyse their effect on sex determination and dosage compensation by producing Drosophila flies that were transgenic for the chimeric SXL proteins. CONCLUSIONS The sex-specific properties of extant Drosophila SXL protein depend on its global structure rather than on a specific domain. This implies that the modifications, mainly in the N- and C-terminal domains, that occurred in the SXL protein during its evolution within the drosophilid lineage represent co-evolutionary changes that determine the appropriate folding of SXL to carry out its sex-specific functions.
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Affiliation(s)
- María Fernanda Ruiz
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Francesca Sarno
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Silvia Zorrilla
- Instituto de Química-Física “Rocasolano”, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Germán Rivas
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Lucas Sánchez
- Centro de Investigaciones Biológicas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
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Kakani EG, Trakala M, Drosopoulou E, Mavragani-Tsipidou P, Mathiopoulos KD. Genomic structure, organization and localization of the acetylcholinesterase locus of the olive fruit fly, Bactrocera oleae. BULLETIN OF ENTOMOLOGICAL RESEARCH 2013; 103:36-47. [PMID: 22967668 DOI: 10.1017/s0007485312000478] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/01/2023]
Abstract
Acetylcholinesterase (AChE), encoded by the ace gene, is a key enzyme of cholinergic neurotransmission. Insensitive acetylcholinesterase (AChE) has been shown to be responsible for resistance to OPs and CBs in a number of arthropod species, including the most important pest of olives trees, the olive fruit fly Bactrocera oleae. In this paper, the organization of the B. oleae ace locus, as well as the structural and functional features of the enzyme, are determined. The organization of the gene was deduced by comparison to the ace cDNA sequence of B. oleae and the organization of the locus in Drosophila melanogaster. A similar structure between insect ace gene has been found, with conserved exon-intron positions and junction sequences. The B. oleae ace locus extends for at least 75 kb, consists of ten exons with nine introns and is mapped to division 34 of the chromosome arm IIL. Moreover, according to bioinformatic analysis, the Bo AChE exhibits all the common features of the insect AChE. Such structural and functional similarity among closely related AChE enzymes may implicate similarities in insecticide resistance mechanisms.
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Affiliation(s)
- E G Kakani
- Department of Biochemistry and Biotechnology, University of Thessaly, Greece
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Doublesex target genes in the red flour beetle, Tribolium castaneum. Sci Rep 2012; 2:948. [PMID: 23230513 PMCID: PMC3517981 DOI: 10.1038/srep00948] [Citation(s) in RCA: 64] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/04/2012] [Accepted: 11/19/2012] [Indexed: 11/08/2022] Open
Abstract
Sex determination cascade in insects terminates with the production of sex-specific protein, Doublesex (Dsx). We identified the dsx homolog (Tcdsx) in Tribolium castaneum. The pre-mRNA of Tcdsx is sex-specifically spliced into three female (Tcdsxf1, Tcdsxf2 and Tcdsxf3) and one male-specific (Tcdsxm) isoforms. Cis-regulatory elements potentially involved in sex-specific splicing of the Tcdsx pre-mRNA were identified in the female-specific exon and the adjoining intronic sequences. All the three female-specific TcDsx proteins share common OD1 and OD2 domains and differ in their C-terminal sequences. Knockdown of Tcdsx resulted in a reduction in the oocyte development, egg production and hatching of eggs laid. Several genes, including those coding for Vitellogenins and Vitellogenin receptors were identified as targets of TcDsx. RNAi experiments showed an isoform-specific targeting of identified target genes by TcDsx as knockdown in the expression of Tcdsx isoforms individually or in combinations resulted in differential effects on the expression of target genes.
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The Am-tra2 gene is an essential regulator of female splice regulation at two levels of the sex determination hierarchy of the honeybee. Genetics 2012; 192:1015-26. [PMID: 22942126 PMCID: PMC3522149 DOI: 10.1534/genetics.112.143925] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
Heteroallelic and homo- or hemiallelic Complementary sex determiner (Csd) proteins determine sexual fate in the honeybee (Apis mellifera) by controlling the alternative splicing of the downstream gene fem (feminizer). Thus far, we have little understanding of how heteroallelic Csd proteins mediate the splicing of female fem messenger RNAs (mRNAs) or how Fem proteins direct the splicing of honeybee dsx (Am-dsx) pre-mRNAs. Here, we report that Am-tra2, which is an ortholog of Drosophila melanogaster tra2, is an essential component of female splicing of the fem and Am-dsx transcripts in the honeybee. The Am-tra2 transcripts are alternatively (but non-sex-specifically) spliced, and they are translated into six protein isoforms that all share the basic RNA-binding domain/RS (arginine/serine) domain structure. Knockdown studies showed that the Am-tra2 gene is required to splice fem mRNAs into the productive female and nonproductive male forms. We suggest that the Am-Tra2 proteins are essential regulators of fem pre-mRNA splicing that, together with heteroallelic Csd proteins and/or Fem proteins, implement the female pathway. In males, the Am-Tra2 proteins may enhance the switch of fem transcripts into the nonproductive male form when heteroallelic Csd proteins are absent. This dual function of Am-Tra2 proteins possibly enhances and stabilizes the binary decision process of male/female splicing. Our knockdown studies also imply that the Am-Tra2 protein is an essential regulator for Am-dsx female splice regulation, suggesting an ancestral role in holometabolous insects. We also provide evidence that the Am-tra2 gene has an essential function in honeybee embryogenesis that is unrelated to sex determination.
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Drosopoulou E, Nakou I, Síchová J, Kubíčková S, Marec F, Mavragani-Tsipidou P. Sex chromosomes and associated rDNA form a heterochromatic network in the polytene nuclei of Bactrocera oleae (Diptera: Tephritidae). Genetica 2012; 140:169-80. [PMID: 22825842 DOI: 10.1007/s10709-012-9668-3] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2012] [Accepted: 07/11/2012] [Indexed: 10/28/2022]
Abstract
The olive fruit fly, Bactrocera oleae, has a diploid set of 2n = 12 chromosomes including a pair of sex chromosomes, XX in females and XY in males, but polytene nuclei show only five polytene chromosomes, obviously formed by five autosome pairs. Here we examined the fate of the sex chromosomes in the polytene complements of this species using fluorescence in situ hybridization (FISH) with the X and Y chromosome-derived probes, prepared by laser microdissection of the respective chromosomes from mitotic metaphases. Specificity of the probes was verified by FISH in preparations of mitotic chromosomes. In polytene nuclei, both probes hybridized strongly to a granular heterochromatic network, indicating thus underreplication of the sex chromosomes. The X chromosome probe (in both female and male nuclei) highlighted most of the granular mass, whereas the Y chromosome probe (in male nuclei) identified a small compact body of this heterochromatic network. Additional hybridization signals of the X probe were observed in the centromeric region of polytene chromosome II and in the telomeres of six polytene arms. We also examined distribution of the major ribosomal DNA (rDNA) using FISH with an 18S rDNA probe in both mitotic and polytene chromosome complements of B. oleae. In mitotic metaphases, the probe hybridized exclusively to the sex chromosomes. The probe signals localized a discrete rDNA site at the end of the short arm of the X chromosome, whereas they appeared dispersed over the entire dot-like Y chromosome. In polytene nuclei, the rDNA was found associated with the heterochromatic network representing the sex chromosomes. Only in nuclei with preserved nucleolar structure, the probe signals were scattered in the restricted area of the nucleolus. Thus, our study clearly shows that the granular heterochromatic network of polytene nuclei in B. oleae is formed by the underreplicated sex chromosomes and associated rDNA.
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Affiliation(s)
- Elena Drosopoulou
- Department of Genetics, Development and Molecular Biology, School of Biology, Faculty of Sciences, Aristotle University of Thessaloniki, Thessaloniki, Greece
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Sobrinho IS, de Brito RA. Positive and purifying selection influence the evolution of doublesex in the Anastrepha fraterculus species group. PLoS One 2012; 7:e33446. [PMID: 22428050 PMCID: PMC3302808 DOI: 10.1371/journal.pone.0033446] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2011] [Accepted: 02/09/2012] [Indexed: 11/19/2022] Open
Abstract
The gene doublesex (dsx) is considered to be under strong selective constraint along its evolutionary history because of its central role in somatic sex differentiation in insects. However, previous studies of dsx used global estimates of evolutionary rates to investigate its molecular evolution, which potentially miss signals of adaptive changes in generally conserved genes. In this work, we investigated the molecular evolution of dsx in the Anastrepha fraterculus species group (Diptera, Tephritidae), and test the hypothesis that this gene evolved solely by purifying selection using divergence-based and population-based methods. In the first approach, we compared sequences from Anastrepha and other Tephritidae with other Muscomorpha species, analyzed variation in nonsynonymous to synonymous rate ratios (dN/dS) in the Tephritidae, and investigated radical and conservative changes in amino acid physicochemical properties. We show a general selective constraint on dsx, but with signs of positive selection mainly in the common region. Such changes were localized in alpha-helices previously reported to be involved in dimer formation in the OD2 domain and near the C-terminal of the OD1 domain. In the population-based approach, we amplified a region of 540 bp that spanned almost all of the region common to both sexes from 32 different sites in Brazil. We investigated patterns of selection using neutrality tests based on the frequency spectrum and locations of synonymous and nonsynonymous mutations in a haplotype network. As in the divergence-based approach, these analyses showed that dsx has evolved under an overall selective constraint, but with some events of positive selection. In contrast to previous studies, our analyses indicate that even though dsx has indeed evolved as a conserved gene, the common region of dsx has also experienced bouts of positive selection, perhaps driven by sexual selection, during its evolution.
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Affiliation(s)
- Iderval S Sobrinho
- Departamento de Genética e Evolução, Universidade Federal de São Carlos, São Carlos, Brazil.
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Mullon C, Pomiankowski A, Reuter M. Molecular evolution of Drosophila Sex-lethal and related sex determining genes. BMC Evol Biol 2012; 12:5. [PMID: 22244243 PMCID: PMC3292462 DOI: 10.1186/1471-2148-12-5] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2011] [Accepted: 01/14/2012] [Indexed: 12/23/2022] Open
Abstract
Background Sex determining mechanisms are evolutionarily labile and related species often use different primary signals and gene regulatory networks. This is well illustrated by the sex determining cascade of Drosophila fruitflies, which have recruited Sex-lethal as the master switch and cellular memory of sexual identity, a role performed in other insects by the gene transformer. Here we investigate the evolutionary change in the coding sequences of sex determining genes associated with the recruitment of Sex-lethal. We analyze sequences of Sex-lethal itself, its Drosophila paralogue sister-or-Sex-lethal and downstream targets transformer and doublesex. Results We find that the recruitment of sister-or-Sex-lethal was associated with a number of adaptive amino acid substitutions, followed by a tightening of purifying selection within the Drosophila clade. Sequences of the paralogue sister-or-Sex-lethal, in contrast, show a signature of rampant positive selection and relaxation of purifying selection. The recruitment of Sex-lethal as top regulator and memory gene is associated with a significant release from purifying selection in transformer throughout the Drosophila clade. In addition, doublesex shows a signature of positive selection and relaxation of purifying selection in the Drosophila clade. A similar pattern is seen in sequences from the sister Tephritidae clade. Conclusions The pattern of molecular evolution we observe for Sex-lethal and its paralogue sister-or-Sex-lethal is not characteristic of a duplication followed by neo-functionalization. Rather, evidence suggests a sub-functionalization scenario achieved through the evolution of sophisticated splicing. As expected, we find that transformer evolves under relaxed purifying selection after the recruitment of Sex-lethal in Drosophila. Finally, the observation of doublesex adaptation in both Drosophila and Tephritidae suggests that these changes are due to ongoing adaptation of downstream sex-specific regulation, rather than being associated the recruitment of Sex-lethal and the resulting change in the topology of the sex determining cascade.
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Affiliation(s)
- Charles Mullon
- Department of Genetics, Environment and Evolution, University College London, Darwin Building, Gower Street, London WC1E 6BT, UK
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Abstract
Animals have evolved a bewildering diversity of mechanisms to determine the two sexes. Studies of sex determination genes – their history and function – in non-model insects and Drosophila have allowed us to begin to understand the generation of sex determination diversity. One common theme from these studies is that evolved mechanisms produce activities in either males or females to control a shared gene switch that regulates sexual development. Only a few small-scale changes in existing and duplicated genes are sufficient to generate large differences in sex determination systems. This review summarises recent findings in insects, surveys evidence of how and why sex determination mechanisms can change rapidly and suggests fruitful areas of future research.
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Affiliation(s)
- Tanja Gempe
- Department of Genetics, Heinrich Heine University, Duesseldorf, Universitaetsstrasse 1, Duesseldorf, Germany
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Gabrieli P, Gomulski LM, Bonomi A, Siciliano P, Scolari F, Franz G, Jessup A, Malacrida AR, Gasperi G. Interchromosomal duplications on the Bactrocera oleae Y chromosome imply a distinct evolutionary origin of the sex chromosomes compared to Drosophila. PLoS One 2011; 6:e17747. [PMID: 21408187 PMCID: PMC3049792 DOI: 10.1371/journal.pone.0017747] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/27/2010] [Accepted: 02/11/2011] [Indexed: 11/19/2022] Open
Abstract
BACKGROUND Diptera have an extraordinary variety of sex determination mechanisms, and Drosophila melanogaster is the paradigm for this group. However, the Drosophila sex determination pathway is only partially conserved and the family Tephritidae affords an interesting example. The tephritid Y chromosome is postulated to be necessary to determine male development. Characterization of Y sequences, apart from elucidating the nature of the male determining factor, is also important to understand the evolutionary history of sex chromosomes within the Tephritidae. We studied the Y sequences from the olive fly, Bactrocera oleae. Its Y chromosome is minute and highly heterochromatic, and displays high heteromorphism with the X chromosome. METHODOLOGY/PRINCIPAL FINDINGS A combined Representational Difference Analysis (RDA) and fluorescence in-situ hybridization (FISH) approach was used to investigate the Y chromosome to derive information on its sequence content. The Y chromosome is strewn with repetitive DNA sequences, the majority of which are also interdispersed in the pericentromeric regions of the autosomes. The Y chromosome appears to have accumulated small and large repetitive interchromosomal duplications. The large interchromosomal duplications harbour an importin-4-like gene fragment. Apart from these importin-4-like sequences, the other Y repetitive sequences are not shared with the X chromosome, suggesting molecular differentiation of these two chromosomes. Moreover, as the identified Y sequences were not detected on the Y chromosomes of closely related tephritids, we can infer divergence in the repetitive nature of their sequence contents. CONCLUSIONS/SIGNIFICANCE The identification of Y-linked sequences may tell us much about the repetitive nature, the origin and the evolution of Y chromosomes. We hypothesize how these repetitive sequences accumulated and were maintained on the Y chromosome during its evolutionary history. Our data reinforce the idea that the sex chromosomes of the Tephritidae may have distinct evolutionary origins with respect to those of the Drosophilidae and other Dipteran families.
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Affiliation(s)
- Paolo Gabrieli
- Department of Animal Biology, University of Pavia, Pavia, Italy
| | | | - Angelica Bonomi
- Department of Animal Biology, University of Pavia, Pavia, Italy
| | - Paolo Siciliano
- Department of Animal Biology, University of Pavia, Pavia, Italy
| | | | - Gerald Franz
- Entomology Unit, FAO/IAEA Agriculture and Biotechnology Laboratory, Joint FAO/IAEA Programme, International Atomic Energy Agency, Vienna, Austria
| | - Andrew Jessup
- Entomology Unit, FAO/IAEA Agriculture and Biotechnology Laboratory, Joint FAO/IAEA Programme, International Atomic Energy Agency, Vienna, Austria
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Concha C, Li F, Scott MJ. Conservation and sex-specific splicing of the doublesex gene in the economically important pest species Lucilia cuprina. J Genet 2011; 89:279-85. [PMID: 20876994 DOI: 10.1007/s12041-010-0039-5] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
Genetic control of sex determination in insects has been best characterized in Drosophila melanogaster, where the master gene Sxl codes for RNA that is sex specifically spliced to produce a functional protein only in females. SXL regulates the sex-specific splicing of transformer (tra) RNA which, in turn, regulates the splicing of dsx RNA to produce functional male and female proteins. In the Australian sheep blowfly (Lucilia cuprina), the tra gene (Lctra) is required for female development and Lctra transcripts are sex-specifically spliced such that only female Lctra mRNA codes for functional protein. In males, a factor encoded by the Y-linked male determining gene is thought to prevent the female-mode of splicing of Lctra RNA. To further our understanding of the sex determination regulatory hierarchy in L. cuprina, we have isolated the dsx gene (Lcdsx) from this species. We found that the Lcdsx transcripts are sex-specifically spliced in a similar manner as their counterparts in D. melanogaster, housefly and tephritids. The LcDSX proteins are well conserved and the male form of DSX contains a motif encoded by a male-specific exon that is within the female-specific intron. This intron/exon arrangement had previously been found only in the housefly dsx gene, suggesting this may be a unique feature of dsx genes of Calyptratae species.
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Affiliation(s)
- Carolina Concha
- Institute of Molecular BioSciences, Massey University, Palmerston North, New Zealand
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MacCarthy T, Seymour RM, Pomiankowski A. Differential regulation drives plasticity in sex determination gene networks. BMC Evol Biol 2010; 10:388. [PMID: 21162741 PMCID: PMC3022605 DOI: 10.1186/1471-2148-10-388] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/07/2010] [Accepted: 12/16/2010] [Indexed: 01/24/2023] Open
Abstract
BACKGROUND Sex determination networks evolve rapidly and have been studied intensely across many species, particularly in insects, thus presenting good models to study the evolutionary plasticity of gene networks. RESULTS We study the evolution of an unlinked gene capable of regulating an existing diploid sex determination system. Differential gene expression determines phenotypic sex and fitness, dramatically reducing the number of assumptions of previous models. It allows us to make a quantitative evaluation of the full range of evolutionary outcomes of the system and an assessment of the likely contribution of sexual conflict to change in sex determination systems. Our results show under what conditions network mutations causing differential regulation can lead to the reshaping of sex determination networks. CONCLUSION The analysis demonstrates the complex relationship between mutation and outcome: the same mutation can produce many different evolved populations, while the same evolved population can be produced by many different mutations. Existing network structure alters the constraints and frequency of evolutionary changes, which include the recruitment of new regulators, changes in heterogamety, protected polymorphisms, and transitions to a new locus that controls sex determination.
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Tsoumani KT, Augustinos AA, Kakani EG, Drosopoulou E, Mavragani-Tsipidou P, Mathiopoulos KD. Isolation, annotation and applications of expressed sequence tags from the olive fly, Bactrocera oleae. Mol Genet Genomics 2010; 285:33-45. [PMID: 20978910 DOI: 10.1007/s00438-010-0583-y] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/28/2010] [Accepted: 10/04/2010] [Indexed: 11/28/2022]
Abstract
The olive fruit fly, Bactrocera oleae, is the major pest of the olive tree. Despite its importance, very little genetic and molecular knowledge is available. The present study is a first attempt to identify and characterize B. oleae expressed sequence tags (ESTs). One hundred and ninety-five randomly selected cDNA clones were isolated and the obtained sequences were annotated through BLASTX similarity searches. A set of 159 unique putative transcripts were functionally assigned using Gene Ontology terms in broad categories of biological process, molecular function and cellular component based on D. melanogaster matches. Moreover, the cytogenetic location of 35 ESTs was determined by in situ hybridization to B. oleae polytene chromosomes. The resulting low-resolution EST map more than doubles the available entry points to the insect's genome and can assist syntenic comparisons with other distant species. The deduced codon usage of the isolated ESTs suggested a conserved pattern of B. oleae with its closest relatives. Additionally, the comparative analysis of B. oleae ESTs with the homologous D. melanogaster genes led to the development of 17 nuclear EPIC-PCR markers for the amplification of intron sequences of 11 Tephritidae species. Sequencing analysis of several cross-amplified intron sequences revealed a high degree of conservation among Bactrocera species and a varying transferability of the generated markers across the examined genera, suggesting that this method can provide a useful tool for the clarification of phylogenetic relationships among different species, particularly in cases of species complexes.
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Affiliation(s)
- K T Tsoumani
- Department of Biochemistry and Biotechnology, University of Thessaly, Larissa, Greece
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Isolation and characterization of Doublesex homologues in the Bactrocera species: B. dorsalis (Hendel) and B. correcta (Bezzi) and their putative promoter regulatory regions. Genetica 2010; 139:113-27. [DOI: 10.1007/s10709-010-9508-2] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2009] [Accepted: 10/12/2010] [Indexed: 11/26/2022]
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Identification of a male-specific RNA binding protein that regulates sex-specific splicing of Bmdsx by increasing RNA binding activity of BmPSI. Mol Cell Biol 2010; 30:5776-86. [PMID: 20956562 DOI: 10.1128/mcb.00444-10] [Citation(s) in RCA: 52] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Bmdsx is a sex-determining gene in the silkworm and is alternatively spliced in males and females. CE1 is a splicing silencer element responsible for the sex-specific splicing of Bmdsx. To identify sex-specific factors implicated in the sex-specific splicing of Bmdsx, we performed RNA affinity chromatography using CE1 RNA as a ligand. We have identified BmIMP, a Bombyx homolog of IGF-II mRNA binding protein (IMP), as a male-specific factor that specifically binds to CE1. The gene encoding BmIMP is localized on the Z chromosome and is male-specifically expressed in various tissues. Antisense inhibition of BmIMP expression increased female-specific splicing of Bmdsx pre-mRNA. Coimmunoprecipitation and glutathione S-transferase (GST) pulldown analyses demonstrated that BmIMP physically interacts with BmPSI, which has been identified as a factor implicated in the sex-specific splicing of Bmdsx, through the KH domains of BmIMP. The functional consequence of this interaction was examined using RNA mobility shift analysis. BmIMP increased BmPSI-CE1 RNA binding activity by decreasing the rate of BmPSI dissociation from CE1 RNA. Truncation analysis of BmIMP suggested that the KH domains are responsible for enhancing BmPSI-CE1 RNA binding activity. These results suggest that BmIMP may enhance the male-specific splicing of Bmdsx pre-mRNA by increasing RNA binding activity of BmPSI.
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The transformer gene of Ceratitis capitata: a paradigm for a conserved epigenetic master regulator of sex determination in insects. Genetica 2010; 139:99-111. [PMID: 20890720 DOI: 10.1007/s10709-010-9503-7] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2010] [Accepted: 09/18/2010] [Indexed: 12/21/2022]
Abstract
The transformer gene in Ceratitis capitata (Cctra(ep)) is the founding member of a family of related SR genes that appear to act as the master epigenetic switch in sex determination in insects. A functional protein seems to be produced only in individuals with a female XX karyotype where it is required to maintain the productive mode of expression through a positive feedback loop and to direct female development by instructing the downstream target genes accordingly. When zygotic activation of this loop is prevented, male development follows. Recently, tra(ep) orthologues were isolated in more distantly related dipteran species including Musca domestica, Glossina morsitans and Lucilia cuprina and in the Hymenopterans Apis mellifera and Nasonia vitripennis. All of these tra(ep) orthologues seem to act as binary switches that govern all aspects of sexual development. Transient silencing leads to complete masculinization of individuals with a female karyotype. Reciprocally, in some systems it has been shown that transient expression of the functional TRA product is sufficient to transactivate the endogenous gene and implement female development in individuals with a male karyotype. Hence, a mechanism based on tra(ep) epigenetic autoregulation seems to represent a common and presumably ancestral single principle of sex determination in Insecta. The results of these studies will not only be important for understanding divergent evolution of basic developmental processes but also for designing new strategies to improve genetic sexing in different insect species of economical or medical importance.
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Shukla JN, Nagaraju J. Doublesex: a conserved downstream gene controlled by diverse upstream regulators. J Genet 2010; 89:341-56. [DOI: 10.1007/s12041-010-0046-6] [Citation(s) in RCA: 80] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
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Dafa’alla T, Fu G, Alphey L. Use of a regulatory mechanism of sex determination in pest insect control. J Genet 2010; 89:301-5. [DOI: 10.1007/s12041-010-0041-y] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
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Insect sex determination: it all evolves around transformer. Curr Opin Genet Dev 2010; 20:376-83. [DOI: 10.1016/j.gde.2010.05.001] [Citation(s) in RCA: 178] [Impact Index Per Article: 12.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/16/2010] [Revised: 04/23/2010] [Accepted: 05/04/2010] [Indexed: 01/20/2023]
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Olafson PU, Lohmeyer KH, Dowd SE. Analysis of expressed sequence tags from a significant livestock pest, the stable fly (Stomoxys calcitrans), identifies transcripts with a putative role in chemosensation and sex determination. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2010; 74:179-204. [PMID: 20572127 DOI: 10.1002/arch.20372] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
The stable fly, Stomoxys calcitrans L. (Diptera: Muscidae), is one of the most significant pests of livestock in the United States. The identification of targets for the development of novel control for this pest species, focusing on those molecules that play a role in successful feeding and reproduction, is critical to mitigating its impact on confined and rangeland livestock. A database was developed representing genes expressed at the immature and adult life stages of the stable fly, comprising data obtained from pyrosequencing both immature and adult stages and from small-scale sequencing of an antennal/maxillary palp-expressed sequence tag library. The full-length sequence and expression of 21 transcripts that may have a role in chemosensation is presented, including 13 odorant-binding proteins, 6 chemosensory proteins, and 2 odorant receptors. Transcripts with potential roles in sex determination and reproductive behaviors are identified, including evidence for the sex-specific expression of stable fly doublesex- and transformer-like transcripts. The current database will be a valuable tool for target identification and for comparative studies with other Diptera.
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Affiliation(s)
- Pia Untalan Olafson
- USDA-ARS, Knipling-Bushland U.S. Livestock Insects Research Laboratory, Kerrville, Texas 78028, USA.
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