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Wang H, Ying J, Mao Z, Wang B, Ye Z, Chen Y, Chen J, Zhang C, Li J, Zhuo J. Identification and functional analysis of the female determiner gene in the bean bug, Riptortus pedestris. PEST MANAGEMENT SCIENCE 2024; 80:1240-1248. [PMID: 37934463 DOI: 10.1002/ps.7853] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/25/2023] [Revised: 08/21/2023] [Accepted: 11/07/2023] [Indexed: 11/08/2023]
Abstract
BACKGROUND Homing-based gene drives targeting sex-specific lethal genes have been used for genetic control. Additionally, understanding insect sex determination provides new targets for managing insect pests. While sex determination mechanisms in holometabolous insects have been thoroughly studied and employed in pest control, the study of the sex determination pathway in hemimetabolous insects is limited to only a few species. Riptortus pedestris (Fabricius; Hemiptera: Heteroptera), commonly known as the bean bug, is a significant pest for soybeans. Nonetheless, the mechanism of its sex determination and the target gene for genetic control are not well understood. RESULTS We identified Rpfmd as the female determiner gene in the sex determination pathway of R. pedestris. Rpfmd encodes a female-specific serine/arginine-rich protein of 436 amino acids and one non-sex-specific short protein of 98 amino acids. Knockdown of Rpfmd in R. pedestris nymphs caused death of molting females with masculinized somatic morphology but did not affect male development. Knockdown of Rpfmd in newly emerged females inhibited ovary development, while maternal-mediated RNA interference (RNAi) knockdown of Rpfmd expression resulted in male-only offspring. Transcriptome sequencing revealed that Rpfmd regulates X chromosome dosage compensation and influences various biological processes in females but has no significant effect on males. Moreover, RNAi mediated knockdown of Rpfmd-C had no influence on the development of R. pedestris, suggesting that Rpfmd regulates sex determination through female-specific splicing isoforms. We also found that Rpfmd pre-mRNA alternative splicing regulation starts at the 24-h embryo stage, indicating the activation of sex differentiation. CONCLUSION Our study confirms that Rpfmd, particularly its female-specific isoform (Rpfmd-F), is the female determiner gene that regulates sex differentiation in R. pedestris. Knockdown of Rpfmd results in female-specific lethality without affecting males, making it a promising target for genetic control of this soybean pest throughout its development stages. Additionally, our findings improve the understanding of the sex-determination mechanism in hemimetabolous insects. © 2023 The Authors. Pest Management Science published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry.
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Affiliation(s)
- Haiqiang Wang
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of MARA and Zhejiang Province, Institute of Plant Virology, Ningbo University, Ningbo, China
| | - Jinjun Ying
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of MARA and Zhejiang Province, Institute of Plant Virology, Ningbo University, Ningbo, China
| | - Zeping Mao
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of MARA and Zhejiang Province, Institute of Plant Virology, Ningbo University, Ningbo, China
| | - Biyun Wang
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of MARA and Zhejiang Province, Institute of Plant Virology, Ningbo University, Ningbo, China
| | - Zhuangxin Ye
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of MARA and Zhejiang Province, Institute of Plant Virology, Ningbo University, Ningbo, China
| | - Youyuan Chen
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of MARA and Zhejiang Province, Institute of Plant Virology, Ningbo University, Ningbo, China
| | - Jianping Chen
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of MARA and Zhejiang Province, Institute of Plant Virology, Ningbo University, Ningbo, China
| | - Chuanxi Zhang
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of MARA and Zhejiang Province, Institute of Plant Virology, Ningbo University, Ningbo, China
| | - Junmin Li
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of MARA and Zhejiang Province, Institute of Plant Virology, Ningbo University, Ningbo, China
| | - Jichong Zhuo
- State Key Laboratory for Managing Biotic and Chemical Threats to the Quality and Safety of Agro-products, Key Laboratory of Biotechnology in Plant Protection of MARA and Zhejiang Province, Institute of Plant Virology, Ningbo University, Ningbo, China
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Liu J, Rayes D, Akbari OS. A Fluorescent Sex-Sorting Technique for Insects with the Demonstration in Drosophila melanogaster. GEN BIOTECHNOLOGY 2024; 3:35-44. [PMID: 38415050 PMCID: PMC10895710 DOI: 10.1089/genbio.2023.0041] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2023] [Accepted: 01/09/2024] [Indexed: 02/29/2024]
Abstract
Recent advances in insect genetic engineering offer alternative genetic biocontrol solutions to control populations of pests and disease vectors. While success has been achieved, sex-sorting remains problematic for scaling many genetic biocontrol interventions. Here, we describe the development of a genetically stable sex-sorting technique for female and male selection with a proof of concept in Drosophila melanogaster termed SEPARATOR (Sexing Element Produced by Alternative RNA-splicing of A Transgenic Observable Reporter). This elegant approach utilizes dominantly expressed fluorescent proteins and differentially spliced introns to ensure sex-specific expression. The system has the potential for adaptability to various insect species and application for high-throughput insect sex-sorting.
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Affiliation(s)
- Junru Liu
- Department of Cell and Developmental Biology, School of Biological Sciences, University of California, San Diego, La Jolla, California, USA
| | - Danny Rayes
- Department of Cell and Developmental Biology, School of Biological Sciences, University of California, San Diego, La Jolla, California, USA
| | - Omar S. Akbari
- Department of Cell and Developmental Biology, School of Biological Sciences, University of California, San Diego, La Jolla, California, USA
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3
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Davydova S, Liu J, Kandul NP, Braswell WE, Akbari OS, Meccariello A. Next-generation genetic sexing strain establishment in the agricultural pest Ceratitis capitata. Sci Rep 2023; 13:19866. [PMID: 37964160 PMCID: PMC10646097 DOI: 10.1038/s41598-023-47276-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/30/2023] [Accepted: 11/11/2023] [Indexed: 11/16/2023] Open
Abstract
Tephritid fruit fly pests pose an increasing threat to the agricultural industry due to their global dispersion and a highly invasive nature. Here we showcase the feasibility of an early-detection SEPARATOR sex sorting approach through using the non-model Tephritid pest, Ceratitis capitata. This system relies on female-only fluorescent marker expression, accomplished through the use of a sex-specific intron of the highly-conserved transformer gene from C. capitata and Anastrepha ludens. The herein characterized strains have 100% desired phenotype outcomes, allowing accurate male-female separation during early development. Overall, we describe an antibiotic and temperature-independent sex-sorting system in C. capitata, which, moving forward, may be implemented in other non-model Tephritid pest species. This strategy can facilitate the establishment of genetic sexing systems with endogenous elements exclusively, which, on a wider scale, can improve pest population control strategies like sterile insect technique.
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Affiliation(s)
- Serafima Davydova
- Department of Life Sciences, Imperial College London, London, SW7 2AZ, UK
| | - Junru Liu
- Department of Cell and Developmental Biology, School of Biological Sciences, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Nikolay P Kandul
- Department of Cell and Developmental Biology, School of Biological Sciences, University of California, San Diego, La Jolla, CA, 92093, USA
| | - W Evan Braswell
- USDA APHIS PPQ Science and Technology Insect Management and Molecular Diagnostic Laboratory, 22675 North Moorefield Road, Edinburg, TX, 78541, USA
| | - Omar S Akbari
- Department of Cell and Developmental Biology, School of Biological Sciences, University of California, San Diego, La Jolla, CA, 92093, USA
| | - Angela Meccariello
- Department of Life Sciences, Imperial College London, London, SW7 2AZ, UK.
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4
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Liu J, Rayes D, Akbari OS. A fluorescent sex-sorting technique for insects with the demonstration in Drosophila melanogaster. BIORXIV : THE PREPRINT SERVER FOR BIOLOGY 2023:2023.08.11.553026. [PMID: 37645836 PMCID: PMC10462037 DOI: 10.1101/2023.08.11.553026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
Recent advances in insect genetic engineering offer alternative genetic biocontrol solutions to control populations of pests and disease vectors. While success has been achieved, sex-sorting remains problematic for scaling many genetic biocontrol interventions. Here we describe the development of a sex-sorting technique for female and male selection with a proof-of-concept in D. melanogaster termed SEPARATOR (Sexing Element Produced by Alternative RNA-splicing of A Transgenic Observable Reporter). This approach utilizes dominant fluorescent proteins and differentially spliced introns to ensure sex-specific expression. The system has the potential for adaptability to various insect species and application for high-throughput insect sex-sorting.
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Affiliation(s)
- Junru Liu
- School of Biological Sciences, Department of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Danny Rayes
- School of Biological Sciences, Department of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093, USA
| | - Omar S. Akbari
- School of Biological Sciences, Department of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA 92093, USA
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5
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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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6
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Schenkel MA, Billeter JC, Beukeboom LW, Pen I. Divergent evolution of genetic sex determination mechanisms along environmental gradients. Evol Lett 2023; 7:132-147. [PMID: 37251583 PMCID: PMC10210438 DOI: 10.1093/evlett/qrad011] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2022] [Revised: 03/06/2023] [Accepted: 03/09/2023] [Indexed: 10/28/2023] Open
Abstract
Sex determination (SD) is a crucial developmental process, but its molecular underpinnings are very diverse, both between and within species. SD mechanisms have traditionally been categorized as either genetic (GSD) or environmental (ESD), depending on the type of cue that triggers sexual differentiation. However, mixed systems, with both genetic and environmental components, are more prevalent than previously thought. Here, we show theoretically that environmental effects on expression levels of genes within SD regulatory mechanisms can easily trigger within-species evolutionary divergence of SD mechanisms. This may lead to the stable coexistence of multiple SD mechanisms and to spatial variation in the occurrence of different SD mechanisms along environmental gradients. We applied the model to the SD system of the housefly, a global species with world-wide latitudinal clines in the frequencies of different SD systems, and found that it correctly predicted these clines if specific genes in the housefly SD system were assumed to have temperature-dependent expression levels. We conclude that environmental sensitivity of gene regulatory networks may play an important role in diversification of SD mechanisms.
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Affiliation(s)
- Martijn A Schenkel
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
| | - Jean-Christophe Billeter
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
| | - Leo W Beukeboom
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
| | - Ido Pen
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
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7
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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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8
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In toto light sheet fluorescence microscopy live imaging datasets of Ceratitis capitata embryonic development. Sci Data 2022; 9:340. [PMID: 35705572 PMCID: PMC9200851 DOI: 10.1038/s41597-022-01443-x] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/31/2022] [Accepted: 06/01/2022] [Indexed: 11/09/2022] Open
Abstract
The Mediterranean fruit fly (medfly), Ceratitis capitata, is an important model organism in biology and agricultural research with high economic relevance. However, information about its embryonic development is still sparse. We share nine long-term live imaging datasets acquired with light sheet fluorescence microscopy (484.5 h total recording time, 373 995 images, 256 Gb) with the scientific community. Six datasets show the embryonic development in toto for about 60 hours at 30 minutes intervals along four directions in three spatial dimensions, covering approximately 97% of the entire embryonic development period. Three datasets focus on germ cell formation and head involution. All imaged embryos hatched morphologically intact. Based on these data, we suggest a two-level staging system that functions as a morphogenetic framework for upcoming studies on medfly. Our data supports research on wild-type or aberrant morphogenesis, quantitative analyses, comparative approaches to insect development as well as studies related to pest control. Further, they can be used to test advanced image processing approaches or to train machine learning algorithms and/or neuronal networks.
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9
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Kandul NP, Liu J, Hsu AD, Hay BA, Akbari OS. A drug-inducible sex-separation technique for insects. Nat Commun 2020; 11:2106. [PMID: 32355156 PMCID: PMC7193620 DOI: 10.1038/s41467-020-16020-2] [Citation(s) in RCA: 13] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/19/2019] [Accepted: 04/07/2020] [Indexed: 11/16/2022] Open
Abstract
Here, we describe a drug-inducible genetic system for insect sex-separation that demonstrates proof-of-principle for positive sex selection in D. melanogaster. The system exploits the toxicity of commonly used broad-spectrum antibiotics geneticin and puromycin to kill the non-rescued sex. Sex-specific rescue is achieved by inserting sex-specific introns into the coding sequences of antibiotic-resistance genes. When raised on geneticin-supplemented food, the sex-sorter line establishes 100% positive selection for female progeny, while the food supplemented with puromycin positively selects 100% male progeny. Since the described system exploits conserved sex-specific splicing mechanisms and reagents, it has the potential to be adaptable to other insect species of medical and agricultural importance.
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Affiliation(s)
- Nikolay P Kandul
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, 92092, USA
| | - Junru Liu
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, 92092, USA
| | - Alexander D Hsu
- Division of Biology and Biological Engineering, MC 156-29, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Bruce A Hay
- Division of Biology and Biological Engineering, MC 156-29, California Institute of Technology, Pasadena, CA, 91125, USA
| | - Omar S Akbari
- Division of Biological Sciences, Section of Cell and Developmental Biology, University of California, San Diego, La Jolla, CA, 92092, USA.
- Division of Biology and Biological Engineering, MC 156-29, California Institute of Technology, Pasadena, CA, 91125, USA.
- Tata Institute for Genetics and Society-UCSD, La Jolla, CA, USA.
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miRNA-1-3p is an early embryonic male sex-determining factor in the Oriental fruit fly Bactrocera dorsalis. Nat Commun 2020; 11:932. [PMID: 32071305 PMCID: PMC7029022 DOI: 10.1038/s41467-020-14622-4] [Citation(s) in RCA: 29] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2018] [Accepted: 07/18/2019] [Indexed: 11/08/2022] Open
Abstract
Regulation of male sexual differentiation by a Y chromosome-linked male determining factor (M-factor) is one of a diverse array of sex determination mechanisms found in insects. By deep sequencing of small RNAs from Bactrocera dorsalis early embryos, we identified an autosomal-derived microRNA, miR-1-3p, that has predicted target sites in the transformer gene (Bdtra) required for female sex determination. We further demonstrate by both in vitro and in vivo tests that miR-1-3p suppresses Bdtra expression. Injection of a miR-1-3p mimic in early embryos results in 87-92% phenotypic males, whereas knockdown of miR-1-3p by an inhibitor results in 67-77% phenotypic females. Finally, CRISPR/Cas9-mediated knockout of miR-1-3p results in the expression of female-specific splice variants of Bdtra and doublesex (Bddsx), and induced sex reversal of XY individuals into phenotypic females. These results indicate that miR-1-3p is required for male sex determination in early embryogenesis in B. dorsalis as an intermediate male determiner.
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11
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Nguantad S, Chumnanpuen P, Thancharoen A, Vongsangnak W, Sriboonlert A. Identification of potential candidate genes involved in the sex determination cascade in an aquatic firefly, Sclerotia aquatilis (Coleoptera, Lampyridae). Genomics 2020; 112:2590-2602. [PMID: 32061895 DOI: 10.1016/j.ygeno.2020.01.025] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/04/2019] [Revised: 01/13/2020] [Accepted: 01/23/2020] [Indexed: 12/27/2022]
Abstract
Sexual differentiation, dimorphism, and courtship behavior are the downstream developmental programs of the sex determination cascade. The sex determination cascade in arthropods often involves key genes, transformer (tra), doublesex (dsx), transformer-2 (tra2), and fruitless (fru). These genes are conserved among insect taxa; however, they have never been reported in fireflies. In this study, the candidate genes for these key genes were identified for the first time in an aquatic firefly, Sclerotia aquatilis using transcriptome analysis. A comparative protein-protein interaction (PPI) network of sex determination cascade was reconstructed for S. aquatilis based on a network of a model insect, Drosophila melanogaster. Subsequently, a sex determination cascade in S. aquatilis was proposed based on the amino acid sequence structures and expression profiles of these candidates. This study describes the first efforts toward understanding the molecular control of sex determination cascade in fireflies.
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Affiliation(s)
- Sarintip Nguantad
- Department of Zoology, Faculty of Science, Kasetsart University, Bangkok, Thailand
| | - Pramote Chumnanpuen
- Department of Zoology, Faculty of Science, Kasetsart University, Bangkok, Thailand; Omics Center for Agriculture, Bioresources, Food, and Health, Kasetsart University (OmiKU), Bangkok 10900, Thailand
| | - Anchana Thancharoen
- Department of Entomology, Faculty of Agriculture, Kasetsart University, Bangkok, Thailand
| | - Wanwipa Vongsangnak
- Department of Zoology, Faculty of Science, Kasetsart University, Bangkok, Thailand; Omics Center for Agriculture, Bioresources, Food, and Health, Kasetsart University (OmiKU), Bangkok 10900, Thailand.
| | - Ajaraporn Sriboonlert
- Department of Genetics, Faculty of Science, Kasetsart University, Bangkok, Thailand.
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12
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Meisel RP, Delclos PJ, Wexler JR. The X chromosome of the German cockroach, Blattella germanica, is homologous to a fly X chromosome despite 400 million years divergence. BMC Biol 2019; 17:100. [PMID: 31806031 PMCID: PMC6894488 DOI: 10.1186/s12915-019-0721-x] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2019] [Accepted: 11/11/2019] [Indexed: 12/30/2022] Open
Abstract
Background Sex chromosome evolution is a dynamic process that can proceed at varying rates across lineages. For example, different chromosomes can be sex-linked between closely related species, whereas other sex chromosomes have been conserved for > 100 million years. Cases of long-term sex chromosome conservation could be informative of factors that constrain sex chromosome evolution. Cytological similarities between the X chromosomes of the German cockroach (Blattella germanica) and most flies suggest that they may be homologous—possibly representing an extreme case of long-term conservation. Results To test the hypothesis that the cockroach and fly X chromosomes are homologous, we analyzed whole-genome sequence data from cockroaches. We found evidence in both sequencing coverage and heterozygosity that a significant excess of the same genes are on both the cockroach and fly X chromosomes. We also present evidence that the candidate X-linked cockroach genes may be dosage compensated in hemizygous males. Consistent with this hypothesis, three regulators of transcription and chromatin on the fly X chromosome are conserved in the cockroach genome. Conclusions Our results support our hypothesis that the German cockroach shares the same X chromosome as most flies. This may represent the convergent evolution of the X chromosome in the lineages leading to cockroaches and flies. Alternatively, the common ancestor of most insects may have had an X chromosome that resembled the extant cockroach and fly X. Cockroaches and flies diverged ∼ 400 million years ago, which would be the longest documented conservation of a sex chromosome. Cockroaches and flies have different mechanisms of sex determination, raising the possibility that the X chromosome was conserved despite the evolution of the sex determination pathway.
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Affiliation(s)
- Richard P Meisel
- Department of Biology and Biochemistry, University of Houston, 3455 Cullen Blvd., Houston, 77204, TX, USA.
| | - Pablo J Delclos
- Department of Biology and Biochemistry, University of Houston, 3455 Cullen Blvd., Houston, 77204, TX, USA
| | - Judith R Wexler
- Department of Ecology and Evolution, University of California, Davis, One Shields Ave, Davis, 95616, CA, USA.,Department of Entomology, University of Maryland, 4112 Plant Sciences Building, College Park, 20742, MD, USA
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13
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García-Reina A, Rossi E, Galián J. Effects of lipopolysaccharide and juvenile hormone III treatments on cell growth and gene expression in the Ceratitis capitata (Diptera: Tephritidae) CCE/CC128 cell line. ARCHIVES OF INSECT BIOCHEMISTRY AND PHYSIOLOGY 2019; 102:e21617. [PMID: 31512283 DOI: 10.1002/arch.21617] [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: 02/01/2019] [Revised: 06/27/2019] [Accepted: 08/16/2019] [Indexed: 06/10/2023]
Abstract
The Mediterranean fruit fly Ceratitis capitata is one of the most important insect pest species in the world. It has a high colonization capacity and population variety, giving it considerable genetic diversity. Strategies for its control have included the sterile insect technique and insect growth regulators. Many studies have analyzed the medfly transcriptome, and along with the medfly genome sequence, the sequences of multiple genes related to sex determination, mating, development, pheromone detection, immunity, or stress have been identified. In this study, the medfly CCE/CC128 cell line was used to assess cell growth variation and changes in the expression of genes covering different functions, after lipopolysaccharide (LPS) and juvenile hormone III (JHIII) treatments. No significant effects on cell growth and gene expression were observed in the cells treated with LPS. In the cells treated with JHIII, the results showed significant effects on cell growth, and an overexpression was found of the Shade gene, one of the Halloween gene members of the cytochrome p450 family, which is involved in development and the synthesis of 20-hydroxyecdysone. This study shows preliminary results on the insect cell line in combination with whole-genome sequencing, which can facilitate studies regarding growth, toxicity, immunity, and transcriptome regulations as a response to different compounds and environmental alterations.
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Affiliation(s)
- Andrés García-Reina
- Department of Zoology and Physical Anthropology, Faculty of Veterinary, Campus Mare Nostrum, University of Murcia, Murcia, Spain
| | | | - José Galián
- Department of Zoology and Physical Anthropology, Faculty of Veterinary, Campus Mare Nostrum, University of Murcia, Murcia, Spain
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Morita S, Ando T, Maeno A, Mizutani T, Mase M, Shigenobu S, Niimi T. Precise staging of beetle horn formation in Trypoxylus dichotomus reveals the pleiotropic roles of doublesex depending on the spatiotemporal developmental contexts. PLoS Genet 2019; 15:e1008063. [PMID: 30969957 PMCID: PMC6457530 DOI: 10.1371/journal.pgen.1008063] [Citation(s) in RCA: 24] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/27/2018] [Accepted: 03/03/2019] [Indexed: 11/19/2022] Open
Abstract
Many scarab beetles have sexually dimorphic exaggerated horns that are an evolutionary novelty. Since the shape, number, size, and location of horns are highly diverged within Scarabaeidae, beetle horns are an attractive model for studying the evolution of sexually dimorphic and novel traits. In beetles including the Japanese rhinoceros beetle Trypoxylus dichotomus, the sex differentiation gene doublesex (dsx) plays a crucial role in sexually dimorphic horn formation during larval-pupal development. However, knowledge of when and how dsx drives the gene regulatory network (GRN) for horn formation to form sexually dimorphic horns during development remains elusive. To address this issue, we identified a Trypoxylus-ortholog of the sex determination gene, transformer (tra), that regulates sex-specific splicing of the dsx pre-mRNA, and whose loss of function results in sex transformation. By knocking down tra function at multiple developmental timepoints during larval-pupal development, we estimated the onset when the sex-specific GRN for horn formation is driven. In addition, we also revealed that dsx regulates different aspects of morphogenetic activities during the prepupal and pupal developmental stages to form appropriate morphologies of pupal head and thoracic horn primordia as well as those of adult horns. Based on these findings, we discuss the evolutionary developmental background of sexually dimorphic trait growth in horned beetles. Beetles in the family Scarabaeidae have various types of horns on their heads and thoraces, and the shape, size, number, and location of these horns are highly diversified within the group. In addition, many scarab beetle horns are sexually dimorphic. The acquisition of these evolutionarily novel horns, and the mechanisms for the diversification of these structures is an interesting question. To address this question, we focused on the rhinoceros beetle Tripoxylus dichotomus. Here we identified the exact developmental timepoints during which the morphological sexual dimorphism of horn primordia appears, estimated the onset of the developmental program for sexually dimorphic horn formation driven by doublesex, and revealed that doublesex regulates different aspects of cell activities during horn formation depending on particular spatiotemporal developmental contexts. Our study provides insights into regulatory shifts in these mechanisms during the evolution of sexually dimorphic traits in horned beetles.
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Affiliation(s)
- Shinichi Morita
- Division of Evolutionary Developmental Biology, National Institute for Basic Biology, 38 Nishigonaka, Myodaiji, Okazaki, Japan
| | - Toshiya Ando
- Division of Evolutionary Developmental Biology, National Institute for Basic Biology, 38 Nishigonaka, Myodaiji, Okazaki, Japan
- Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), 38 Nishigonaka, Myodaiji, Okazaki, Japan
| | - Akiteru Maeno
- Mammalian Genetics Laboratory, Genetic Strains Research Center, National Institute of Genetics, Mishima, Shizuoka, Japan
| | - Takeshi Mizutani
- Division of Evolutionary Developmental Biology, National Institute for Basic Biology, 38 Nishigonaka, Myodaiji, Okazaki, Japan
| | - Mutsuki Mase
- Division of Evolutionary Developmental Biology, National Institute for Basic Biology, 38 Nishigonaka, Myodaiji, Okazaki, Japan
- Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya, Japan
| | - Shuji Shigenobu
- Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), 38 Nishigonaka, Myodaiji, Okazaki, Japan
- NIBB Core Research Facilities, National Institute for Basic Biology, 38 Nishigonaka Myodaiji, Okazaki, Japan
| | - Teruyuki Niimi
- Division of Evolutionary Developmental Biology, National Institute for Basic Biology, 38 Nishigonaka, Myodaiji, Okazaki, Japan
- Department of Basic Biology, School of Life Science, SOKENDAI (The Graduate University for Advanced Studies), 38 Nishigonaka, Myodaiji, Okazaki, Japan
- Graduate School of Bioagricultural Sciences, Nagoya University, Chikusa, Nagoya, Japan
- * E-mail:
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15
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Abstract
The global economic cost of Aedes-borne diseases, such as dengue, is estimated to be in the billions of dollars annually. In this scenario, a sustained vector control strategy is the only alternative to control dengue, as well as other diseases transmitted by Aedes, including Zika and chikungunya. The use of transgenic mosquitoes is a promising weapon in the improvement of approaches currently applied in Aedes aegypti control. Field trials using genetically modified mosquitoes for population control have been conducted and offer an excellent opportunity to evaluate what can be improved. In a mass-rearing mosquito facility, the absence of a transgenic line that produces male-only progeny is undoubtedly a limiting factor; thus, being able to manipulate sex determination in this species is a fundamental step for the success of this strategy. Likewise, the possibility of manipulation of the sex determination pathway opens-up a new opportunity for disease control.
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Affiliation(s)
| | - Bianca Burini Kojin
- Department of Entomology, Texas A & M University, Minnie Belle Heep Center, College Station, TX, USA
| | - Margareth Lara Capurro
- Department of Parasitology, Institute of Biomedical Sciences, University of São Paulo, São Paulo, Brasil.
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Geuverink E, Kraaijeveld K, van Leussen M, Chen F, Pijpe J, Linskens MHK, Beukeboom LW, van de Zande L. Evidence for involvement of a transformer paralogue in sex determination of the wasp Leptopilina clavipes. INSECT MOLECULAR BIOLOGY 2018; 27:780-795. [PMID: 30039559 DOI: 10.1111/imb.12522] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Transformer (tra) is the central gear in many insect sex determination pathways and transduces a wide range of primary signals. Mediated by transformer-2 (tra2) it directs sexual development into the female or male mode. Duplications of tra have been detected in numerous Hymenoptera, but a function in sex determination has been confirmed only in Apis mellifera. We identified a tra2 orthologue (Lc-tra2), a tra orthologue (Lc-tra) and a tra paralogue (Lc-traB) in the genome of Leptopilina clavipes (Hymenoptera: Cynipidae). We compared the sequence and structural conservation of these genes between sexual (arrhenotokous) and asexual all-female producing (thelytokous) individuals. Lc-tra is sex-specifically spliced in adults consistent with its orthologous function. The male-specific regions of Lc-tra are conserved in both reproductive modes. The paralogue Lc-traB lacks the genomic region coding for male-specific exons and can only be translated into a full-length TRA-like peptide sequence. Furthermore, unlike LC-TRA, the LC-TRAB interstrain sequence variation is not differentiated into a sexual and an asexual haplotype. The LC-TRAB protein interacts with LC-TRA as well as LC-TRA2. This suggests that Lc-traB functions as a conserved element in sex determination of sexual and asexual individuals.
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Affiliation(s)
- E Geuverink
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
| | - K Kraaijeveld
- Department of Ecological Science, Vrije Universiteit Amsterdam, Amsterdam, The Netherlands
- Leiden Genome Technology Center, Department of Human Genetics, Leiden University Medical Center, Leiden, The Netherlands
| | - M van Leussen
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
| | - F Chen
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
| | - J Pijpe
- University of Applied Sciences Leiden, Leiden, The Netherlands
| | - M H K Linskens
- Groningen Biomolecular Sciences and Biotechnology Institute, University of Groningen, Groningen, The Netherlands
| | - L W Beukeboom
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
| | - L van de Zande
- Groningen Institute for Evolutionary Life Sciences, University of Groningen, Groningen, The Netherlands
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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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18
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Bombyx mori P-element Somatic Inhibitor (BmPSI) Is a Key Auxiliary Factor for Silkworm Male Sex Determination. PLoS Genet 2017; 13:e1006576. [PMID: 28103247 PMCID: PMC5289617 DOI: 10.1371/journal.pgen.1006576] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/31/2016] [Revised: 02/02/2017] [Accepted: 01/10/2017] [Indexed: 12/23/2022] Open
Abstract
Manipulation of sex determination pathways in insects provides the basis for a wide spectrum of strategies to benefit agriculture and public health. Furthermore, insects display a remarkable diversity in the genetic pathways that lead to sex differentiation. The silkworm, Bombyx mori, has been cultivated by humans as a beneficial insect for over two millennia, and more recently as a model system for studying lepidopteran genetics and development. Previous studies have identified the B. mori Fem piRNA as the primary female determining factor and BmMasc as its downstream target, while the genetic scenario for male sex determination was still unclear. In the current study, we exploite the transgenic CRISPR/Cas9 system to generate a comprehensive set of knockout mutations in genes BmSxl, Bmtra2, BmImp, BmImpM, BmPSI and BmMasc, to investigate their roles in silkworm sex determination. Absence of Bmtra2 results in the complete depletion of Bmdsx transcripts, which is the conserved downstream factor in the sex determination pathway, and induces embryonic lethality. Loss of BmImp or BmImpM function does not affect the sexual differentiation. Mutations in BmPSI and BmMasc genes affect the splicing of Bmdsx and the female reproductive apparatus appeared in the male external genital. Intriguingly, we identify that BmPSI regulates expression of BmMasc, BmImpM and Bmdsx, supporting the conclusion that it acts as a key auxiliary factor in silkworm male sex determination. The sex determination system extremely diverse among organisms including insects in which even each order occupy a different manner of sex determination. The silkworm, Bombyx mori, is a lepidopteran model insect with economic importance. The mechanism of the silkworm sex determination has been in mystery for a long time until a Fem piRNA was identified as the primary female sex determinator recently. However, genetic and phenotypic proofs are urgently needed to fully exploit the mechanism, especially of the male sex determination. In the current study, we provided comprehensively genetic evidences by generating CRISPR/Cas9-mediated knockout mutations for those genes BmSxl, Bmtra2, BmImp, BmImpM, BmPSI and BmMasc, which were considered to be involved in insect sex determination. The results showed that mutations of BmSxl, BmImp and BmImpM had no physiological and morphological effects on the sexual development while Bmtra2 depletion caused Bmdsx splicing disappeared and induced embryonic lethality. Importantly, the BmPSI regulates expression of BmMasc, BmImpM and Bmdsx, supporting the conclusion that it acts as a key auxiliary factor to regulate the male sex determination in the silkworm.
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Handler AM. Enhancing the stability and ecological safety of mass-reared transgenic strains for field release by redundant conditional lethality systems. INSECT SCIENCE 2016; 23:225-234. [PMID: 26097098 DOI: 10.1111/1744-7917.12245] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Accepted: 05/05/2015] [Indexed: 06/04/2023]
Abstract
The genetic manipulation of agriculturally important insects now allows the development of genetic sexing and male sterility systems for more highly efficient biologically-based population control programs, most notably the Sterile Insect Technique (SIT), for both plant and animal insect pests. Tetracycline-suppressible (Tet-off) conditional lethal systems may function together so that transgenic strains will be viable and fertile on a tetracycline-containing diet, but female-lethal and male sterile in tetracycline-free conditions. This would allow their most efficacious use in a unified system for sterile male-only production for SIT. A critical consideration for the field release of such transgenic insect strains, however, is a determination of the frequency and genetic basis of lethality revertant survival. This will provide knowledge essential to evaluating the genetic stability of the lethality system, its environmental safety, and provide the basis for modifications ensuring optimal efficacy. For Tet-off lethal survival determinations, development of large-scale screening protocols should also allow the testing of these modifications, and test the ability of other conditional lethal systems to fully suppress propagation of rare Tet-off survivors. If a dominant temperature sensitive (DTS) pupal lethality system proves efficient for secondary lethality in Drosophila, it may provide the safeguard needed to support the release of sexing/sterility strains, and potentially, the release of unisex lethality strains as a form of genetic male sterility. Should the DTS Prosβ2(1) mutation prove effective for redundant lethality, its high level of structural and functional conservation should allow host-specific cognates to be created for a wide range of insect species.
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Affiliation(s)
- Alfred M Handler
- USDA, Agricultural Research Service, Center for Medical, Agricultural and Veterinary Entomology, Gainesville, FL, 32608, USA
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20
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Charlesworth D. Plant contributions to our understanding of sex chromosome evolution. THE NEW PHYTOLOGIST 2015; 208:52-65. [PMID: 26053356 DOI: 10.1111/nph.13497] [Citation(s) in RCA: 77] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Accepted: 05/01/2015] [Indexed: 05/06/2023]
Abstract
A minority of angiosperms have male and female flowers separated in distinct individuals (dioecy), and most dioecious plants do not have cytologically different (heteromorphic) sex chromosomes. Plants nevertheless have several advantages for the study of sex chromosome evolution, as genetic sex determination has evolved repeatedly and is often absent in close relatives. I review sex-determining regions in non-model plant species, which may help us to understand when and how (and, potentially, test hypotheses about why) recombination suppression evolves within young sex chromosomes. I emphasize high-throughput sequencing approaches that are increasingly being applied to plants to test for non-recombining regions. These data are particularly illuminating when combined with sequence data that allow phylogenetic analyses, and estimates of when these regions evolved. Together with comparative genetic mapping, this has revealed that sex-determining loci and sex-linked regions evolved independently in many plant lineages, sometimes in closely related dioecious species, and often within the past few million years. In reviewing recent progress, I suggest areas for future work, such as the use of phylogenies to allow the informed choice of outgroup species suitable for inferring the directions of changes, including testing whether Y chromosome-like regions are undergoing genetic degeneration, a predicted consequence of losing recombination.
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Affiliation(s)
- Deborah Charlesworth
- Institute of Evolutionary Biology, University of Edinburgh, Ashworth Lab, King's Buildings, W. Mains Road, Edinburgh, EH9 3FL, UK
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21
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Hamm RL, Meisel RP, Scott JG. The evolving puzzle of autosomal versus Y-linked male determination in Musca domestica. G3 (BETHESDA, MD.) 2014; 5:371-84. [PMID: 25552607 PMCID: PMC4349091 DOI: 10.1534/g3.114.014795] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/12/2014] [Accepted: 12/27/2014] [Indexed: 11/18/2022]
Abstract
Sex determination is one of the most rapidly evolving developmental pathways, but the factors responsible for this fast evolution are not well resolved. The house fly, Musca domestica, is an ideal model for studying sex determination because house fly sex determination is polygenic and varies considerably between populations. Male house flies possess a male-determining locus, the M factor, which can be located on the Y or X chromosome or any of the five autosomes. There can be a single M or multiple M factors present in an individual male, in heterozygous or homozygous condition. Males with multiple copies of M skew the sex ratio toward the production of males. Potentially in response to these male-biased sex ratios, an allele of the gene transformer, Md-tra(D), promotes female development in the presence of one or multiple M factors. There have been many studies to determine the linkage and frequency of these male determining factors and the frequency of Md-tra(D) chromosomes in populations from around the world. This review provides a summary of the information available to date regarding the patterns of distribution of autosomal, X-linked and Y-linked M factors, the relative frequencies of the linkage of M, the changes in frequencies found in field populations, and the fitness of males with autosomal M factors vs. Y-linked M. We evaluate this natural variation in the house fly sex determination pathway in light of models of the evolution of sex determination.
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Affiliation(s)
| | - Richard P Meisel
- Department of Biology and Biochemistry, University of Houston, Houston, Texas 77204
| | - Jeffrey G Scott
- Department of Entomology, Comstock Hall, Cornell University, Ithaca, New York 14853
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22
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Chen P, Xu SL, Zhou W, Guo XG, Wang CL, Wang DL, Zhao YL. Cloning and expression analysis of a transformer gene in Daphnia pulex during different reproduction stages. Anim Reprod Sci 2014; 146:227-37. [DOI: 10.1016/j.anireprosci.2014.03.010] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/05/2014] [Revised: 03/13/2014] [Accepted: 03/17/2014] [Indexed: 01/16/2023]
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Gilles JR, Schetelig MF, Scolari F, Marec F, Capurro ML, Franz G, Bourtzis K. Towards mosquito sterile insect technique programmes: exploring genetic, molecular, mechanical and behavioural methods of sex separation in mosquitoes. Acta Trop 2014; 132 Suppl:S178-87. [PMID: 23994521 DOI: 10.1016/j.actatropica.2013.08.015] [Citation(s) in RCA: 68] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2013] [Revised: 08/12/2013] [Accepted: 08/19/2013] [Indexed: 12/20/2022]
Abstract
When considering a mosquito release programme, one of the first issues to be addressed is how to eliminate/separate the females. The greatest number of options might eventually be available for those who can use transgenic mosquitoes, but the inherent characteristics of the target species may also provide possibilities for interim measures until more efficient methods can be developed. Differences in intrinsic size, in behaviour and in development rate between females and males are often available and useful for sexing. Efficient species-specific systems for eliminating females at the embryo stage have been developed, but most have since been discarded due to lack of use. Ideal systems specifically kill female embryos using some treatment that can be manipulated during production. Such killing systems are far more efficient than using intrinsic sexual differences, but they systems require selectable genetic markers and sex-linkage created by rare random chromosomal rearrangements. While intrinsic sexual differences should not be considered as long-term candidates for the development of robust and efficient sexing approaches, in the absence of these, the accessibility and integration of less efficient systems can provide a stop-gap measure that allows rapid start up with a minimum of investment. The International Atomic Energy Agency is funding over a 5 year period (2013-2018) a new Coordinated Research Project on "Exploring Genetic, Molecular, Mechanical and Behavioural Methods of Sex Separation in Mosquitoes" to network researchers and to address the critical need of genetic sexing strains for the implementation of the sterile insect technique (using radiation-sterilised or transgenic male mosquitoes) and for insect incompatibility technique programmes against disease-transmitting mosquitoes.
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Koukidou M, Alphey L. Practical applications of insects' sexual development for pest control. Sex Dev 2014; 8:127-36. [PMID: 24401199 DOI: 10.1159/000357203] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Elucidation of the sex differentiation pathway in insects offers an opportunity to understand key aspects of evolutionary developmental biology. In addition, it provides the understanding necessary to manipulate insects in order to develop new synthetic genetics-based tools for the control of pest insects. Considerable progress has been made in this, especially in improvements to the sterile insect technique (SIT). Large scale sex separation is considered highly desirable or essential for most SIT targets. This separation can be provided by genetic methods based on sex-specific gene expression. Investigation of sex determination by many groups has provided molecular components and methods for this. Though the primary sex determination signal varies considerably, key regulatory genes and mechanisms remain surprisingly similar. In most cases studied so far, a primary signal is transmitted to a basal gene at the bottom of the hierarchy (dsx) through an alternative splicing cascade; dsx is itself differentially spliced in males and females. A sex-specific alternative splicing system therefore offers an attractive route to achieve female-specific expression. Experience has shown that alternative splicing modules can be developed with cross-species function; modularity and standardisation and re-use of parts are key principles of synthetic biology. Both female-killing and sex reversal (XX females to phenotypic males) can in principle also be used as efficient alternatives to sterilisation in SIT-like methods. Sexual maturity is yet another area where understanding of sexual development may be applied to insect control programmes. Further detailed understanding of this crucial aspect of insect biology will undoubtedly continue to underpin innovative practical applications.
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Bopp D, Saccone G, Beye M. Sex determination in insects: variations on a common theme. Sex Dev 2013; 8:20-8. [PMID: 24335049 DOI: 10.1159/000356458] [Citation(s) in RCA: 94] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Recent studies in a representative selection of holometabolous insects suggest that, despite diversity at the instructive level, the signal-relaying part of the sex-determining pathway is remarkably well conserved. In principle, it is composed of the transformer gene (tra), which acts as a common binary switch that transduces the selected sexual fate, female when ON, male when OFF, to the downstream effector doublesex(dsx) that controls overt sexual differentiation. An interesting recurrent feature is that tra is switched ON in the early zygote by maternally provisioned tra activity. Different male-determining signals evolved, which prevent maternal activation of zygotic tra to allow for male development. In some species, where lack of maternal activation leaves tra in the OFF state, novel female-determining signals were deployed to activate zygotic tra. It appears that both the instructive end of the pathway upstream of tra as well as the executive end downstream of dsx are primary targets of evolutionary divergence, while the transduction part seems less prone to changes. We propose that this is a feature shared with many other signaling cascades that regulate developmental fates.
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Affiliation(s)
- D Bopp
- Institute of Molecular Life Sciences, University of Zurich, Zurich, Switzerland
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26
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Salvemini M, D'Amato R, Petrella V, Aceto S, Nimmo D, Neira M, Alphey L, Polito LC, Saccone G. The orthologue of the fruitfly sex behaviour gene fruitless in the mosquito Aedes aegypti: evolution of genomic organisation and alternative splicing. PLoS One 2013; 8:e48554. [PMID: 23418412 PMCID: PMC3572092 DOI: 10.1371/journal.pone.0048554] [Citation(s) in RCA: 40] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2012] [Accepted: 09/26/2012] [Indexed: 12/23/2022] Open
Abstract
In Drosophila melanogaster the doublesex (dsx) and fruitless (fru) regulatory genes act at the bottom of the somatic sex determination pathway. Both are regulated via alternative splicing by an upstream female-specific TRA/TRA-2 complex, recognizing a common cis element. dsx controls somatic sexual differentiation of non-neural as well as of neural tissues. fru, on the other hand, expresses male-specific functions only in neural system where it is required to built the neural circuits underlying proper courtship behaviour. In the mosquito Aedes aegypti sex determination is different from Drosophila. The key male determiner M, which is located on one of a pair of homomorphic sex chromosomes, controls sex-specific splicing of the mosquito dsx orthologue. In this study we report the genomic organization and expression of the fru homologue in Ae. aegypti (Aeafru). We found that it is sex-specifically spliced suggesting that it is also under the control of the sex determination pathway. Comparative analyses between the Aeafru and Anopheles gambiae fru (Angfru) genomic loci revealed partial conservation of exon organization and extensive divergence of intron lengths. We find that Aeadsx and Aeafru share novel cis splicing regulatory elements conserved in the alternatively spliced regions. We propose that in Aedes aegypti sex-specific splicing of dsx and fru is most likely under the control of splicing regulatory factors which are different from TRA and TRA-2 found in other dipteran insects and discuss the potential use of fru and dsx for developing new genetic strategies in vector control.
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Affiliation(s)
- Marco Salvemini
- Department of Biological Sciences - Section of Genetics and Molecular Biology, University of Naples Federico II, Naples, Italy.
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27
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Ogaugwu CE, Schetelig MF, Wimmer EA. Transgenic sexing system for Ceratitis capitata (Diptera: Tephritidae) based on female-specific embryonic lethality. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2013; 43:1-8. [PMID: 23137881 DOI: 10.1016/j.ibmb.2012.10.010] [Citation(s) in RCA: 44] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Revised: 10/11/2012] [Accepted: 10/28/2012] [Indexed: 06/01/2023]
Abstract
Fruit fly pest species have been successfully controlled and managed via the Sterile Insect Technique (SIT), a control strategy that uses infertile matings of sterile males to wild females to reduce pest populations. Biological efficiency in the field is higher if only sterile males are released in SIT programs and production costs are also reduced. Sexing strains developed in the Mediterranean fruit fly Ceratitis capitata (medfly) through classical genetics are immensely beneficial to medfly SIT programs but exhibit reduced fertility and fitness. Moreover, transfer of such classical genetic systems to other tephritid species is difficult. Transgenic approaches can overcome this limitation of classical genetic sexing strains (GSSs), but had resulted so far in transgenic sexing strains (TSSs) with dominant lethality at late larval and pupal stages. Here we present a transgene-based female-specific lethality system for early embryonic sexing in medfly. The system utilizes the sex-specifically spliced transformer intron to restrict ectopic mRNA translation of the pro-apoptotic gene hid(Ala5) to females only. The expression of this lethal effector gene is driven by a tetracycline-repressible transactivator gene tTA that is under the control of promoters/enhancers of early-acting cellularization genes. Despite observed position effects on the sex-specific splicing, we could effectively establish this early-acting transgenic sexing system in the medfly C. capitata. After satisfactory performance in large scale tests, TSSs based on this system will offer cost-effective sexing once introduced into SIT programs. Moreover, this approach is straight forward to be developed also for other insect pest and vector species.
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Affiliation(s)
- Christian E Ogaugwu
- Department of Developmental Biology, Georg-August-University Göttingen, GZMB, Ernst-Caspari-Haus, Johann-Friedrich-Blumenbach Institute of Zoology and Anthropology, Justus-von-Liebig-Weg 11, 37077 Göttingen, Germany
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Schetelig MF, Handler AM. A transgenic embryonic sexing system for Anastrepha suspensa (Diptera: Tephritidae). INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2012; 42:790-795. [PMID: 22858603 DOI: 10.1016/j.ibmb.2012.07.007] [Citation(s) in RCA: 45] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/23/2012] [Revised: 07/19/2012] [Accepted: 07/22/2012] [Indexed: 06/01/2023]
Abstract
The Sterile Insect Technique (SIT) is a highly successful biologically-based strategy to control pest insect populations that relies on the large-scale release of sterilized males to render females in the field non-reproductive. For medfly, a mutant-based sexing system is available as well as a transgenic system where a tetracycline-suppressible (Tet-off) toxic molecule is female-specifically produced. However, the former classical genetic system took many years to refine, and the latter system results in female death by a poorly understood mechanism, primarily in the pupal stage after rearing costs have been incurred. Here we describe a Tet-off transgenic embryonic sexing system (TESS) for Anastrepha suspensa that uses a driver construct having the promoter from the embryo-specific A. suspensa serendipity α gene, linked to the Tet-transactivator. This was used to drive the expression of a phospho-mutated variant of the pro-apoptotic cell death gene, Alhid, from Anastrepha ludens. The system uses a sex-specific intron splicing cassette linked to a cell death gene lethal effector. Progeny from TESS strains heterozygous for the transgene combination were 80-100% males, whereas four double homozygous TESS strains had 100% male-only progeny, with female death limited primarily to embryogenesis. In a large-scale test, more than 30,000 eggs from two strains resulted in 100% male-only progeny. The transgenic sexing approach described here is highly effective and cost-efficient by eliminating most, if not all, female insects early in embryogenesis using a well-characterized apoptotic mechanism.
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Affiliation(s)
- Marc F Schetelig
- USDA/ARS, Center for Medical, Agricultural and Veterinary Entomology, 1700 SW 23rd Drive, Gainesville, FL 32608, USA.
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Sex determination in beetles: production of all male progeny by parental RNAi knockdown of transformer. Sci Rep 2012; 2:602. [PMID: 22924109 PMCID: PMC3426794 DOI: 10.1038/srep00602] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Accepted: 08/10/2012] [Indexed: 12/22/2022] Open
Abstract
Sex in insects is determined by a cascade of regulators ultimately controlling sex-specific splicing of a transcription factor, Doublesex (Dsx). We recently identified homolog of dsx in the red flour beetle, Tribolium castaneum (Tcdsx). Here, we report on the identification and characterization of a regulator of Tcdsx splicing in T. castaneum. Two male-specific and one female-specific isoforms of T. castaneum transformer (Tctra) were identified. RNA interference-aided knockdown of Tctra in pupa or adults caused a change in sex from females to males by diverting the splicing of Tcdsx pre-mRNA to male-specific isoform. All the pupa and adults developed from Tctra dsRNA injected final instar larvae showed male-specific sexually dimorphic structures. Tctra parental RNAi caused an elimination of females from the progeny resulting in production of all male progeny. Transformer parental RNAi could be used to produce all male population for use in pest control though sterile male release methods.
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Requirements for effective malaria control with homing endonuclease genes. Proc Natl Acad Sci U S A 2011; 108:E874-80. [PMID: 21976487 DOI: 10.1073/pnas.1110717108] [Citation(s) in RCA: 130] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023] Open
Abstract
Malaria continues to impose a substantial burden on human health. We have previously proposed that biological approaches to control the mosquito vector of disease could be developed using homing endonuclease genes (HEGs), a class of selfish or parasitic gene that exists naturally in many microbes. Recent lab studies have demonstrated that HEGs can function in mosquitoes. We constructed and analyzed a model of mosquito population genetics and malaria epidemiology to determine how well HEGs need to function in order to have a significant effect on the burden of disease. Our model, combined with currently available data, indicates that populations of Anopheles gambiae could be eliminated by releasing 2-3 HEGs targeting female fertility genes, or a driving-Y chromosome that is transmitted to 75-96% of progeny. Combinations of fertility-targeting HEGs and Y drive may also be effective. It is possible to eliminate the disease without eliminating the vector, but the parameter space producing this outcome appears to be small. HEGs causing a quantitative reduction in adult survival can be more effective than those targeting female fertility, but the selection coefficients that need to be imposed are still large, unless many HEGs are to be released. Simulations show that HEG-based strategies can be effective over socially relevant time frames. Important limiting assumptions of the models are that there is only a single vector species, and we model a homogeneous population, not a landscape. Nevertheless, we conclude that HEG-based approaches could have a transformational effect on malaria control efforts.
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31
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Chandler CH, Chadderdon GE, Phillips PC, Dworkin I, Janzen FJ. Experimental evolution of the Caenorhabditis elegans sex determination pathway. Evolution 2011; 66:82-93. [PMID: 22220866 DOI: 10.1111/j.1558-5646.2011.01420.x] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Sex determination is a critical developmental decision with major ecological and evolutionary consequences, yet a large variety of sex determination mechanisms exist and we have a poor understanding of how they evolve. Theoretical and empirical work suggest that compensatory adaptations to mutations in genes involved in sex determination may play a role in the evolution of these pathways. Here, we directly address this problem using experimental evolution in Caenorhabditis elegans lines fixed for a pair of mutations in two key sex-determining genes that jointly render sex determination temperature-sensitive and cause intersexual (but still weakly to moderately fertile) phenotypes at intermediate temperatures. After 50 generations, evolved lines clearly recovered toward wild-type phenotypes. However, changes in transcript levels of key sex-determining genes in evolved lines cannot explain their partially (or in some cases, nearly completely) rescued phenotypes, implying that wild-type phenotypes can be restored independently of the transcriptional effects of these mutations. Our findings highlight the microevolutionary flexibility of sex determination pathways and suggest that compensatory adaptation to mutations can elicit novel and unpredictable evolutionary trajectories in these pathways, mirroring the phylogenetic diversity, and macroevolutionary dynamics of sex determination mechanisms.
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Affiliation(s)
- Christopher H Chandler
- Department of Ecology, Evolution, and Organismal Biology, Iowa State University, Ames, Iowa 50011, USA
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32
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Salz HK. Sex determination in insects: a binary decision based on alternative splicing. Curr Opin Genet Dev 2011; 21:395-400. [PMID: 21474300 DOI: 10.1016/j.gde.2011.03.001] [Citation(s) in RCA: 113] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2011] [Accepted: 03/11/2011] [Indexed: 12/22/2022]
Abstract
The gene regulatory networks that control sex determination vary between species. Despite these differences, comparative studies in insects have found that alternative splicing is reiteratively used in evolution to control expression of the key sex-determining genes. Sex determination is best understood in Drosophila where activation of the RNA binding protein-encoding gene Sex-lethal is the central female-determining event. Sex-lethal serves as a genetic switch because once activated it controls its own expression by a positive feedback splicing mechanism. Sex fate choice in is also maintained by self-sustaining positive feedback splicing mechanisms in other dipteran and hymenopteran insects, although different RNA binding protein-encoding genes function as the binary switch. Studies exploring the mechanisms of sex-specific splicing have revealed the extent to which sex determination is integrated with other developmental regulatory networks.
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Affiliation(s)
- Helen K Salz
- Department of Genetics, School of Medicine, Case Western Reserve University, Cleveland, OH 44106-4955, USA.
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Salvemini M, Polito C, Saccone G. Fruitless alternative splicing and sex behaviour in insects: an ancient and unforgettable love story? J Genet 2011; 89:287-99. [PMID: 20876995 DOI: 10.1007/s12041-010-0040-z] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/20/2023]
Abstract
Courtship behaviours are common features of animal species that reproduce sexually. Typically, males are involved in courting females. Insects display an astonishing variety of courtship strategies primarily based on innate stereotyped responses to various external stimuli. In Drosophila melanogaster, male courtship requires proteins encoded by the fruitless (fru) gene that are produced in different sex-specific isoforms via alternative splicing. Drosophila mutant flies with loss-of-function alleles of the fru gene exhibit blocked male courtship behaviour. However, various individual steps in the courtship ritual are disrupted in fly strains carrying different fru alleles. These findings suggest that fru is required for specific steps in courtship. In distantly related insect species, various fru paralogues were isolated, which shows conservation of sex-specific alternative splicing and protein expression in neural tissues and suggests an evolutionary functional conservation of fru in the control of male-specific courtship behaviour. In this review, we report the seminal findings regarding the fru gene, its splicing regulation and evolution in insects.
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Affiliation(s)
- Marco Salvemini
- Department of Biological Sciences, University of Naples Federico II, 80134, Naples, Italy
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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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Evidence for positive selection in the gene fruitless in Anastrepha fruit flies. BMC Evol Biol 2010; 10:293. [PMID: 20868501 PMCID: PMC2958917 DOI: 10.1186/1471-2148-10-293] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/27/2010] [Accepted: 09/24/2010] [Indexed: 01/22/2023] Open
Abstract
Background Many genes involved in the sex determining cascade have indicated signals of positive selection and rapid evolution across different species. Even though fruitless is an important gene involved mostly in several aspects of male courtship behavior, the few studies so far have explained its high rates of evolution by relaxed selective constraints. This would indicate that a large portion of this gene has evolved neutrally, contrary to what has been observed for other genes in the sex cascade. Results Here we test whether the fruitless gene has evolved neutrally or under positive selection in species of Anastrepha (Tephritidae: Diptera) using two different approaches, a long-term evolutionary analysis and a populational genetic data analysis. The first analysis was performed by using sequences of three species of Anastrepha and sequences from several species of Drosophila using the ratio of nonsynonymous to synonymous rates of evolution in PAML, which revealed that the fru region here studied has evolved by positive selection. Using Bayes Empirical Bayes we estimated that 16 sites located in the connecting region of the fruitless gene were evolving under positive selection. We also investigated for signs of this positive selection using populational data from 50 specimens from three species of Anastrepha from different localities in Brazil. The use of standard tests of selection and a new test that compares patterns of differential survival between synonymous and nonsynonymous in evolutionary time also provide evidence of positive selection across species and of a selective sweep for one of the species investigated. Conclusions Our data indicate that the high diversification of fru connecting region in Anastrepha flies is due at least in part to positive selection, not merely as a consequence of relaxed selective constraint. These conclusions are based not only on the comparison of distantly related taxa that show long-term divergence time, but also on recently diverged lineages and suggest that episodes of adaptive evolution in fru may be related to sexual selection and/or conflict related to its involvement in male courtship behavior.
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36
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Baker RH, Wilkinson GS. Comparative Genomic Hybridization (CGH) reveals a neo-X chromosome and biased gene movement in stalk-eyed flies (genus Teleopsis). PLoS Genet 2010; 6:e1001121. [PMID: 20862308 PMCID: PMC2940734 DOI: 10.1371/journal.pgen.1001121] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/23/2010] [Accepted: 08/13/2010] [Indexed: 12/21/2022] Open
Abstract
Chromosomal location has a significant effect on the evolutionary dynamics of genes involved in sexual dimorphism, impacting both the pattern of sex-specific gene expression and the rate of duplication and protein evolution for these genes. For nearly all non-model organisms, however, knowledge of chromosomal gene content is minimal and difficult to obtain on a genomic scale. In this study, we utilized Comparative Genomic Hybridization (CGH), using probes designed from EST sequence, to identify genes located on the X chromosome of four species in the stalk-eyed fly genus Teleopsis. Analysis of log(2) ratio values of female-to-male hybridization intensities from the CGH microarrays for over 3,400 genes reveals a strongly bimodal distribution that clearly differentiates autosomal from X-linked genes for all four species. Genotyping of 33 and linkage mapping of 28 of these genes in Teleopsis dalmanni indicate the CGH results correctly identified chromosomal location in all cases. Syntenic comparison with Drosophila indicates that 90% of the X-linked genes in Teleopsis are homologous to genes located on chromosome 2L in Drosophila melanogaster, suggesting the formation of a nearly complete neo-X chromosome from Muller element B in the dipteran lineage leading to Teleopsis. Analysis of gene movement both relative to Drosophila and within Teleopsis indicates that gene movement is significantly associated with 1) rates of protein evolution, 2) the pattern of gene duplication, and 3) the evolution of eyespan sexual dimorphism. Overall, this study reveals that diopsids are a critical group for understanding the evolution of sex chromosomes within Diptera. In addition, we demonstrate that CGH is a useful technique for identifying chromosomal sex-linkage and should be applicable to other organisms with EST or partial genomic information.
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Affiliation(s)
- Richard H Baker
- Sackler Institute for Comparative Genomics, American Museum of Natural History, New York, New York, USA.
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37
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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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38
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Beukeboom LW, Van De Zande L. Genetics of sex determination in the haplodiploid wasp Nasonia vitripennis (Hymenoptera: Chalcidoidea). J Genet 2010; 89:333-9. [DOI: 10.1007/s12041-010-0045-7] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
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39
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Charlesworth D, Mank JE. The birds and the bees and the flowers and the trees: lessons from genetic mapping of sex determination in plants and animals. Genetics 2010; 186:9-31. [PMID: 20855574 PMCID: PMC2940314 DOI: 10.1534/genetics.110.117697] [Citation(s) in RCA: 120] [Impact Index Per Article: 8.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023] Open
Abstract
The ability to identify genetic markers in nonmodel systems has allowed geneticists to construct linkage maps for a diversity of species, and the sex-determining locus is often among the first to be mapped. Sex determination is an important area of study in developmental and evolutionary biology, as well as ecology. Its importance for organisms might suggest that sex determination is highly conserved. However, genetic studies have shown that sex determination mechanisms, and the genes involved, are surprisingly labile. We review studies using genetic mapping and phylogenetic inferences, which can help reveal evolutionary pattern within this lability and potentially identify the changes that have occurred among different sex determination systems. We define some of the terminology, particularly where confusion arises in writing about such a diverse range of organisms, and highlight some major differences between plants and animals, and some important similarities. We stress the importance of studying taxa suitable for testing hypotheses, and the need for phylogenetic studies directed to taxa where the patterns of changes can be most reliably inferred, if the ultimate goal of testing hypotheses regarding the selective forces that have led to changes in such an essential trait is to become feasible.
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Affiliation(s)
- Deborah Charlesworth
- Department of Zoology, Edward Grey Institute, University of Oxford, Oxford OX1 3PS, United Kingdom.
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40
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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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41
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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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42
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Verhulst EC, Beukeboom LW, van de Zande L. Maternal control of haplodiploid sex determination in the wasp Nasonia. Science 2010; 328:620-3. [PMID: 20431014 DOI: 10.1126/science.1185805] [Citation(s) in RCA: 153] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
All insects in the order Hymenoptera have haplodiploid sex determination, in which males emerge from haploid unfertilized eggs and females are diploid. Sex determination in the honeybee Apis mellifera is controlled by the complementary sex determination (csd) locus, but the mechanisms controlling sex determination in other Hymenoptera without csd are unknown. We identified the sex-determination system of the parasitic wasp Nasonia, which has no csd locus. Instead, maternal input of Nasonia vitripennis transformer (Nvtra) messenger RNA, in combination with specific zygotic Nvtra transcription, in which Nvtra autoregulates female-specific splicing, is essential for female development. Our data indicate that males develop as a result of maternal imprinting that prevents zygotic transcription of the maternally derived Nvtra allele in unfertilized eggs. Upon fertilization, zygotic Nvtra transcription is initiated, which autoregulates the female-specific transcript, leading to female development.
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Affiliation(s)
- Eveline C Verhulst
- Evolutionary Genetics, Centre for Ecological and Evolutionary Studies, University of Groningen, Netherlands
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43
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Sexual development in Lucilia cuprina (Diptera, Calliphoridae) is controlled by the transformer gene. Genetics 2009; 182:785-98. [PMID: 19433631 DOI: 10.1534/genetics.109.100982] [Citation(s) in RCA: 97] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Insects use an amazing variety of genetic systems to control sexual development. A Y-linked male determining gene (M) controls sex in the Australian sheep blowfly Lucilia cuprina, an important pest insect. In this study, we isolated the L. cuprina transformer (Lctra) and transformer2 (Lctra2) genes, which are potential targets of M. The LCTRA and LCTRA2 proteins are significantly more similar to homologs from tephritid insects than Drosophila. The Lctra transcript is alternatively spliced such that only females make a full-length protein and the presence of six TRA/TRA2 binding sites in the female first intron suggest that Lctra splicing is autoregulated as in tephritids. LCTRA is essential for female development as RNAi knockdown of Lctra mRNA leads to the development of male genitalia in XX adults. Analysis of Lctra expression during development shows that early and midstage male and female embryos express the female form of Lctra and males express only the male form by the first instar larval stage. Our results suggest that an autoregulatory loop sustains female development and that expression of M inhibits Lctra autoregulation, switching its splicing to the male form. The conservation of tra function and regulation in a Calliphorid insect shows that this sex determination system is not confined to Tephritidae. Isolation of these genes is an important step toward the development of a strain of L. cuprina suitable for a genetic control program.
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Abstract
In several insects and fish, and probably some mammals, the gene controlling the male-female switch has changed during evolution. It now seems that this has also happened in honeybees, where the sex-determining gene has now been shown to be a duplicate of another Hymenopteran sex-determining gene.
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Affiliation(s)
- Deborah Charlesworth
- Institute of Evolutionary Biology, School of Biological Sciences, University of Edinburgh, Ashworth Lab. King's Buildings, W. Mains Road, Edinburgh EH9 3JT, UK.
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45
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The population genetics of using homing endonuclease genes in vector and pest management. Genetics 2008; 179:2013-26. [PMID: 18660532 DOI: 10.1534/genetics.108.089037] [Citation(s) in RCA: 168] [Impact Index Per Article: 10.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
Homing endonuclease genes (HEGs) encode proteins that in the heterozygous state cause double-strand breaks in the homologous chromosome at the precise position opposite the HEG. If the double-strand break is repaired using the homologous chromosome, the HEG becomes homozygous, and this represents a powerful genetic drive mechanism that might be used as a tool in managing vector or pest populations. HEGs may be used to decrease population fitness to drive down population densities (possibly causing local extinction) or, in disease vectors, to knock out a gene required for pathogen transmission. The relative advantages of HEGs that target viability or fecundity, that are active in one sex or both, and whose target is expressed before or after homing are explored. The conditions under which escape mutants arise are also analyzed. A different strategy is to place HEGs on the Y chromosome that cause one or more breaks on the X chromosome and so disrupt sex ratio. This strategy can cause severe sex-ratio biases with efficiencies that depend on the details of sperm competition and zygote mortality. This strategy is probably less susceptible to escape mutants, especially when multiple X shredders are used.
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46
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Gomulski LM, Dimopoulos G, Xi Z, Soares MB, Bonaldo MF, Malacrida AR, Gasperi G. Gene discovery in an invasive tephritid model pest species, the Mediterranean fruit fly, Ceratitis capitata. BMC Genomics 2008; 9:243. [PMID: 18500975 PMCID: PMC2427042 DOI: 10.1186/1471-2164-9-243] [Citation(s) in RCA: 54] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/06/2008] [Accepted: 05/23/2008] [Indexed: 12/02/2022] Open
Abstract
Background The medfly, Ceratitis capitata, is a highly invasive agricultural pest that has become a model insect for the development of biological control programs. Despite research into the behavior and classical and population genetics of this organism, the quantity of sequence data available is limited. We have utilized an expressed sequence tag (EST) approach to obtain detailed information on transcriptome signatures that relate to a variety of physiological systems in the medfly; this information emphasizes on reproduction, sex determination, and chemosensory perception, since the study was based on normalized cDNA libraries from embryos and adult heads. Results A total of 21,253 high-quality ESTs were obtained from the embryo and head libraries. Clustering analyses performed separately for each library resulted in 5201 embryo and 6684 head transcripts. Considering an estimated 19% overlap in the transcriptomes of the two libraries, they represent about 9614 unique transcripts involved in a wide range of biological processes and molecular functions. Of particular interest are the sequences that share homology with Drosophila genes involved in sex determination, olfaction, and reproductive behavior. The medfly transformer2 (tra2) homolog was identified among the embryonic sequences, and its genomic organization and expression were characterized. Conclusion The sequences obtained in this study represent the first major dataset of expressed genes in a tephritid species of agricultural importance. This resource provides essential information to support the investigation of numerous questions regarding the biology of the medfly and other related species and also constitutes an invaluable tool for the annotation of complete genome sequences. Our study has revealed intriguing findings regarding the transcript regulation of tra2 and other sex determination genes, as well as insights into the comparative genomics of genes implicated in chemosensory reception and reproduction.
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Affiliation(s)
- Ludvik M Gomulski
- Department of Animal Biology, University of Pavia, Piazza Botta 9, Pavia 27100, Italy.
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47
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The gene transformer of anastrepha fruit flies (Diptera, tephritidae) and its evolution in insects. PLoS One 2007; 2:e1239. [PMID: 18043746 PMCID: PMC2080774 DOI: 10.1371/journal.pone.0001239] [Citation(s) in RCA: 63] [Impact Index Per Article: 3.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2007] [Accepted: 10/26/2007] [Indexed: 11/30/2022] Open
Abstract
In the tephritids Ceratitis capitata and Bactrocera oleae, the gene transformer acts as the memory device for sex determination, via an auto-regulatory function; and functional Tra protein is produced only in females. This paper investigates the evolution of the gene tra, which was characterised in twelve tephritid species belonging to the less extensively analysed genus Anastrepha. Our study provided the following major conclusions. Firstly, the memory device mechanism used by this gene in sex determination in tephritids likely existed in the common ancestor of the Ceratitis, Bactrocera and Anastrepha phylogenetic lineages. This mechanism would represent the ancestral state with respect to the extant cascade seen in the more evolved Drosophila lineage. Secondly, Transformer2-specific binding intronic splicing silencer sites were found in the splicing regulatory region of transformer but not in doublesex pre-mRNAs in these tephritids. Thus, these sites probably provide the discriminating feature for the putative dual splicing activity of the Tra-Tra2 complex in tephritids. It acts as a splicing activator in dsx pre-mRNA splicing (its binding to the female-specific exon promotes the inclusion of this exon into the mature mRNA), and as a splicing inhibitor in tra pre-mRNA splicing (its binding to the male-specific exons prevents the inclusion of these exons into the mature mRNA). Further, a highly conserved region was found in the specific amino-terminal region of the tephritid Tra protein that might be involved in Tra auto-regulatory function and hence in its repressive splicing behaviour. Finally, the Tra proteins conserved the SR dipeptides, which are essential for Tra functionality.
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Sex-specific splicing of the honeybee doublesex gene reveals 300 million years of evolution at the bottom of the insect sex-determination pathway. Genetics 2007; 177:1733-41. [PMID: 17947419 DOI: 10.1534/genetics.107.078980] [Citation(s) in RCA: 89] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Sex-determination mechanisms vary greatly among taxa. It has been proposed that genetic sex-determination pathways evolve in reverse order from the final step in the pathway to the first step. Consistent with this hypothesis, doublesex (dsx), the most downstream gene in the Drosophila sex-determination cascade that determines most sexual phenotypes also determines sex in other dipterans and the silk moth, while the upstream genes vary among these species. However, it is unknown when dsx was recruited to the sex-determination pathway during insect evolution. Furthermore, sex-specific splicing of dsx, by which dsx determines sex, is different in pattern and mechanism between the moth and the fly, raising an interesting question of how these insects have kept the executor of sex determination while allowing flexibility in the means of execution. To address these questions, here we study the dsx gene of the honeybee Apis mellifera, a member of the most basal lineage of holometabolous insects. We report that honeybee dsx is sex-specifically spliced and that it produces both the fly-type and moth-type splicing forms, indicating that the use of different splicing forms of Dsx in controlling sexual differentiation was present in the common ancestor of holometabolous insects. Our data suggest that in ancestral holometabolous insects the female Dsx form is the default and the male form is generated by suppressing the splicing of the female form. Thus, it is likely that the dsx splicing activator system in flies, where the male form is the default, arose during early dipteran evolution.
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Lagos D, Koukidou M, Savakis C, Komitopoulou K. The transformer gene in Bactrocera oleae: the genetic switch that determines its sex fate. INSECT MOLECULAR BIOLOGY 2007; 16:221-30. [PMID: 17298554 DOI: 10.1111/j.1365-2583.2006.00717.x] [Citation(s) in RCA: 64] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/13/2023]
Abstract
Transformer (tra) is the second gene of a regulatory cascade based on RNA splicing that determines sex in Drosophila melanogaster. Splicing of tra transcripts is regulated by the master gene Sex lethal and tra itself regulates splicing of the transcriptional regulator doublesex (dsx). We present the isolation and characterization of Botra, the olive fruit fly Bactrocera oleae orthologue to the Drosophila gene transformer. As in Drosophila, Botra transcripts are spliced in a sex-specific manner so that only females encode a functional polypeptide of 422 amino acids, whereas males encode presumably nonfunctional peptide(s). The identification of multiple TRA/TRA-2 binding sites within the Botra male-specific exons, suggests an autoregulation mechanism of tra, through TRA/TRA2 activities. The fundamental role of the TRA protein in sex determination of Bactrocera was investigated by RNA interference, where the introduction of Botra dsRNA into embryos resulted in complete transformation of XX flies into fertile males.
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Affiliation(s)
- D Lagos
- Division of Genetics and Biotechnology, Department of Biology, University of Athens, Panepistimiopolis, Kouponia, Athens, Greece
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Fu G, Condon KC, Epton MJ, Gong P, Jin L, Condon GC, Morrison NI, Dafa'alla TH, Alphey L. Female-specific insect lethality engineered using alternative splicing. Nat Biotechnol 2007; 25:353-7. [PMID: 17322873 DOI: 10.1038/nbt1283] [Citation(s) in RCA: 186] [Impact Index Per Article: 10.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/12/2006] [Accepted: 09/14/2006] [Indexed: 11/09/2022]
Abstract
The Sterile Insect Technique is a species-specific and environmentally friendly method of pest control involving mass release of sterilized insects that reduce the wild population through infertile matings. Insects carrying a female-specific autocidal genetic system offer an attractive alternative to conventional sterilization methods while also eliminating females from the release population. We exploited sex-specific alternative splicing in insects to engineer female-specific autocidal genetic systems in the Mediterranean fruit fly, Ceratitis capitata. These rely on the insertion of cassette exons from the C. capitata transformer gene into a heterologous tetracycline-repressible transactivator such that the transactivator transcript is disrupted in male splice variants but not in the female-specific one. As the key components of these systems function across a broad phylogenetic range, this strategy addresses the paucity of sex-specific expression systems (e.g., early-acting, female-specific promoters) in insects other than Drosophila melanogaster. The approach may have wide applicability for regulating gene expression in other organisms, particularly for combinatorial control with appropriate promoters.
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Affiliation(s)
- Guoliang Fu
- Oxitec Limited, 71 Milton Park, Oxford OX14 4RX, UK
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