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Liang J, Kang L, Michalak P, Sharakhov IV. Hybridization between Aedes aegypti and Aedes mascarensis mosquitoes leads to disruption of male sex determination. Commun Biol 2024; 7:886. [PMID: 39039226 PMCID: PMC11263339 DOI: 10.1038/s42003-024-06560-4] [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: 01/22/2024] [Accepted: 07/05/2024] [Indexed: 07/24/2024] Open
Abstract
Understanding the sex determination pathway and its disruptions in mosquitoes is critical for the effective control of disease vectors through genetic manipulations based on sex separation. When male hybrids of Aedes aegypti females and Ae. mascarensis males are backcrossed to Ae. aegypti females, a portion of the backcross progeny manifests as males with abnormal sexual differentiation. We discovered a significant correlation between pupal abnormalities and the feminization of subsequent adults exemplified by the relative abundance of ovarian and testicular tissues. All intersex individuals were genetic males as they expressed a male determining factor, Nix. Further, our analysis of the sex-specific splicing of doublesex and fruitless transcripts demonstrated the presence of both male and female splice variants indicating that sex determination is disrupted. A comparative transcriptomic analysis revealed similar expression levels of most female-associated genes in reproductive organs and carcasses between intersexual males and normal females. Moreover, intersexes had largely normal gene expression in testes but significant gene downregulation in male accessory glands when compared with normal males. We conclude that evolving hybrid incompatibilities between Ae. aegypti and Ae. mascarensis involve disruption of sex determination and are accompanied by changes in gene expression associated with sexual differentiation.
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Affiliation(s)
- Jiangtao Liang
- Department of Entomology, Virginia Polytechnic and State University, Blacksburg, VA, USA
- Fralin Life Science Institute, Virginia Polytechnic and State University, Blacksburg, VA, USA
- Center for Emerging, Zoonotic, and Arthropod-borne Pathogens, Virginia Polytechnic and State University, Blacksburg, VA, USA
| | - Lin Kang
- Department of Biomedical Research, Edward Via College of Osteopathic Medicine, Monroe, LA, USA
- College of Pharmacy, University of Louisiana Monroe, Monroe, LA, USA
- Center for One Health Research, VA-MD College of Veterinary Medicine, Blacksburg, VA, USA
| | - Pawel Michalak
- Department of Biomedical Research, Edward Via College of Osteopathic Medicine, Monroe, LA, USA
- Center for One Health Research, VA-MD College of Veterinary Medicine, Blacksburg, VA, USA
- Institute of Evolution, University of Haifa, Haifa, Israel
| | - Igor V Sharakhov
- Department of Entomology, Virginia Polytechnic and State University, Blacksburg, VA, USA.
- Fralin Life Science Institute, Virginia Polytechnic and State University, Blacksburg, VA, USA.
- Center for Emerging, Zoonotic, and Arthropod-borne Pathogens, Virginia Polytechnic and State University, Blacksburg, VA, USA.
- Department of Genetics and Cell Biology, Tomsk State University, Tomsk, Russia.
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Baker CA, Guan XJ, Choi M, Murthy M. The role of fruitless in specifying courtship behaviors across divergent Drosophila species. SCIENCE ADVANCES 2024; 10:eadk1273. [PMID: 38478605 PMCID: PMC10936877 DOI: 10.1126/sciadv.adk1273] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 08/04/2023] [Accepted: 02/08/2024] [Indexed: 04/20/2024]
Abstract
Sex-specific behaviors are critical for reproduction and species survival. The sex-specifically spliced transcription factor fruitless (fru) helps establish male courtship behaviors in invertebrates. Forcing male-specific fru (fruM) splicing in Drosophila melanogaster females produces male-typical behaviors while disrupting female-specific behaviors. However, whether fru's joint role in specifying male and inhibiting female behaviors is conserved across species is unknown. We used CRISPR-Cas9 to force FruM expression in female Drosophila virilis, a species in which males and females produce sex-specific songs. In contrast to D. melanogaster, in which one fruM allele is sufficient to generate male behaviors in females, two alleles are needed in D. virilis females. D. virilis females expressing FruM maintain the ability to sing female-typical song as well as lay eggs, whereas D. melanogaster FruM females cannot lay eggs. These results reveal potential differences in fru function between divergent species and underscore the importance of studying diverse behaviors and species for understanding the genetic basis of sex differences.
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Affiliation(s)
| | - Xiao-Juan Guan
- Princeton Neuroscience Institute, Princeton University, Princeton, NJ, USA
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3
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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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Kientega M, Kranjc N, Traoré N, Kaboré H, Soma DD, Morianou I, Namountougou M, Belem AMG, Diabaté A. Analysis of the Genetic Variation of the Fruitless Gene within the Anopheles gambiae ( Diptera: Culicidae) Complex Populations in Africa. INSECTS 2022; 13:1048. [PMID: 36421951 PMCID: PMC9699577 DOI: 10.3390/insects13111048] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 09/14/2022] [Revised: 10/06/2022] [Accepted: 10/24/2022] [Indexed: 06/16/2023]
Abstract
Targeting genes involved in sexual determinism, for vector or pest control purposes, requires a better understanding of their polymorphism in natural populations in order to ensure a rapid spread of the construct. By using genomic data from An. gambiae s.l., we analyzed the genetic variation and the conservation score of the fru gene in 18 natural populations across Africa. A total of 34,339 SNPs were identified, including 3.11% non-synonymous segregating sites. Overall, the nucleotide diversity was low, and the Tajima’s D neutrality test was negative, indicating an excess of low frequency SNPs in the fru gene. The allelic frequencies of the non-synonymous SNPs were low (freq < 0.26), except for two SNPs identified at high frequencies (freq > 0.8) in the zinc-finger A and B protein domains. The conservation score was variable throughout the fru gene, with maximum values in the exonic regions compared to the intronic regions. These results showed a low genetic variation overall in the exonic regions, especially the male sex-specific exon and the BTB-exon 1 of the fru gene. These findings will facilitate the development of an effective gene drive construct targeting the fru gene that can rapidly spread without encountering resistance in wild populations.
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Affiliation(s)
- Mahamadi Kientega
- Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso 01 BP 545, Burkina Faso
- Laboratoire de Santé Animale Tropicale, Institut du Développement Rural, Université Nazi Boni, Bobo-Dioulasso 01 BP 1091, Burkina Faso
| | - Nace Kranjc
- Department of Life Sciences, Imperial College, London SW7 2AZ, UK
| | - Nouhoun Traoré
- Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso 01 BP 545, Burkina Faso
- Laboratoire de Santé Animale Tropicale, Institut du Développement Rural, Université Nazi Boni, Bobo-Dioulasso 01 BP 1091, Burkina Faso
| | - Honorine Kaboré
- Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso 01 BP 545, Burkina Faso
- Laboratoire de Santé Animale Tropicale, Institut du Développement Rural, Université Nazi Boni, Bobo-Dioulasso 01 BP 1091, Burkina Faso
| | - Dieudonné Diloma Soma
- Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso 01 BP 545, Burkina Faso
- Laboratoire de Santé Animale Tropicale, Institut du Développement Rural, Université Nazi Boni, Bobo-Dioulasso 01 BP 1091, Burkina Faso
| | - Ioanna Morianou
- Department of Life Sciences, Imperial College, London SW7 2AZ, UK
| | - Moussa Namountougou
- Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso 01 BP 545, Burkina Faso
- Laboratoire de Santé Animale Tropicale, Institut du Développement Rural, Université Nazi Boni, Bobo-Dioulasso 01 BP 1091, Burkina Faso
| | - Adrien Marie Gaston Belem
- Laboratoire de Santé Animale Tropicale, Institut du Développement Rural, Université Nazi Boni, Bobo-Dioulasso 01 BP 1091, Burkina Faso
| | - Abdoulaye Diabaté
- Institut de Recherche en Sciences de la Santé (IRSS), Bobo-Dioulasso 01 BP 545, Burkina Faso
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Thaijongrak P, Chotwiwatthanakun C, Laphyai P, Prachumwat A, Kruangkum T, Sobhon P, Vanichviriyakit R. Molecular characterization and expression profiling of transformer 2 and fruitless-like homologs in the black tiger shrimp, Penaeus monodon. PeerJ 2022; 10:e12980. [PMID: 35194532 PMCID: PMC8858584 DOI: 10.7717/peerj.12980] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/11/2021] [Accepted: 01/31/2022] [Indexed: 01/11/2023] Open
Abstract
Transformer 2 (tra 2) and fruitless (fru) genes have been proven to play a key role in sex determination pathways in many Arthropods, including insects and crustaceans. In this study, a paralog of P. monodon tra 2 (Pmtra 2), P. monodon ovarian associated transformer 2 (PmOvtra 2) and 2 isoforms of P. monodon fruitless-like gene (Pmfru-1 and Pmfru-2) were identified and characterized. The full cDNA sequence of PmOvtra 2 consisted of 1,774 bp with the longest open reading frame (ORF) of 744 bp encoding for 247 amino acids. The PmOvtra 2 exhibited a predicted RNA-recognition motif (RRM) domain and two arginine-serine (RS) regions, suggesting its function in RNA splicing. The full cDNA sequence of Pmfru-1 consisted of 1,306 bp with 1,182 bp ORF encoding for 393 amino acids, whereas the full cDNA sequence of Pmfru-2 consisted of 1,858 bp with 1,437 bp ORF encoding 478 amino acids. The deduced amino acid sequences of Pmfru-1 and Pmfru-2 exhibited highly conserved domains of Fru proteins, including Broad-complex, Tramtrack and Bric-a-brac (BTB), and zinc finger (ZF) domains. In addition, Pmfru-1 and Pmfru-2 were suggestively originated from the same single genomic locus by genomic sequence analysis. Specifically, Pmfru pre-mRNA was alternatively spliced for Pmfru-1 and Pmfru-2 to include mutually exclusive exon 7 and exon 6, respectively. Temporal and spatial expression of PmOvtra 2, Pmfru-1, and Pmfru-2 were also investigated by qPCR. The results showed that all were expressed in early developmental stages with undifferentiated gonads starting from nauplius until postlarvae. The expression of PmOvtra 2 started at nauplius stage and gradually increased from mysis to postlarvae (PL) 1. However, the expression of Pmfru-1 was low at the nauplii stage and slightly increased from protozoea to PL5, whereas the expression of Pmfru-2 maintained a low level from nauplius to mysis and then gradually increased at the PL stages. Expressions of PmOvtra 2, Pmfru-1, and Pmfru-2 were detected in various tissues including nervous tissue, gill, heart, hepatopancreas, gut, and gonads. Interestingly, the sexually dimorphic expression of PmOvtra 2, Pmfru-1, and Pmfru-2 was demonstrated in fully developed gonads in which the ovary showed significantly higher expressions than the testis. The great difference in the expression pattern of PmOvtra 2, Pmfru-1, and Pmfru-2 in the ovary and testis suggested their roles in the female sex determination in P. monodon.
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Affiliation(s)
- Prawporn Thaijongrak
- Center of Excellence for Shrimp Molecular Biology and Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand,Department of Anatomy, Faculty of Science, Mahidol University, Bangkok, Thailand,Department of Clinical Sciences and Public Health, Faculty of Veterinary Science, Mahidol University, Nakhon Pathom, Thailand
| | - Charoonroj Chotwiwatthanakun
- Center of Excellence for Shrimp Molecular Biology and Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand,Nakhonsawan Campus, Mahidol University, Nakhonsawan, Thailand
| | - Phaivit Laphyai
- Center of Excellence for Shrimp Molecular Biology and Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand,Department of Anatomy, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Anuphap Prachumwat
- Center of Excellence for Shrimp Molecular Biology and Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand,National Center for Genetic Engineering and Biotechnology, National Science and Technology Development Agency, Pathum Thani, Thailand
| | - Thanapong Kruangkum
- Center of Excellence for Shrimp Molecular Biology and Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand,Department of Anatomy, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Prasert Sobhon
- Department of Anatomy, Faculty of Science, Mahidol University, Bangkok, Thailand
| | - Rapeepun Vanichviriyakit
- Center of Excellence for Shrimp Molecular Biology and Biotechnology, Faculty of Science, Mahidol University, Bangkok, Thailand,Department of Anatomy, Faculty of Science, Mahidol University, Bangkok, Thailand
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Jin B, Zhao Y, Dong Y, Liu P, Sun Y, Li X, Zhang X, Chen XG, Gu J. Alternative splicing patterns of doublesex reveal a missing link between Nix and doublesex in the sex determination cascade of Aedes albopictus. INSECT SCIENCE 2021; 28:1601-1620. [PMID: 33179439 DOI: 10.1111/1744-7917.12886] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2020] [Revised: 10/26/2020] [Accepted: 10/28/2020] [Indexed: 05/06/2023]
Abstract
Sexual development in insects is regulated by a complicated hierarchical cascade of sex determination. The primary signals are diverse, whereas the central nexus doublesex (dsx) gene is relatively conserved within the pathway. Aedes (Stegomyia) albopictus is an important vector with an extensive worldwide distribution. We previously reported that Ae. albopictus dsx (Aalbdsx) yields one male- (AalbdsxM ) and three female-specific isoforms (AalbdsxF1-3 ); however, the spatiotemporal expression profiles and mechanisms regulating sex-specific alternative splicing require further investigation. In this study, we demonstrated that the AalbdsxM messenger RNA (mRNA) represents the default pattern when analyzed in human foreskin fibroblasts and HeLa cells. We combined reverse transcription polymerase chain reaction with RNA immunoprecipitation using specific antibodies against tagged Ae. albopictus male-determining factor AalNix and confirmed that AalNix indirectly regulates dsx pre-mRNA and regulates its alternative splicing. During the early embryo stage (0-2 and 4-8 h), maternal dsxF and default splicing dsxM were detected in both sexes; the expression of dsxM then decreased until sufficient AalNix transcripts accumulated in male embryos at 20-24 h. These findings suggest that one or more potential dsx splicing enhancers can shift dsxM to dsxF in both sexes; however, the presence of Nix influences the function of this unknown splicing enhancer and ultimately leads to the formation of dsxM in males. Finally, our results provide important insight into the regulatory mechanism of dsx alternative splicing in the mosquito.
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Affiliation(s)
- Binbin Jin
- Department of Pathogen Biology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, 510515, China
| | - Yijie Zhao
- Department of Pathogen Biology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, 510515, China
| | - Yunqiao Dong
- Reproductive Medical Centre of Guangdong Women and Children Hospital, Guangzhou, 511442, China
| | - Peiwen Liu
- Department of Pathogen Biology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, 510515, China
| | - Yan Sun
- Department of Pathogen Biology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, 510515, China
| | - Xiaocong Li
- Department of Pathogen Biology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, 510515, China
| | - Xin Zhang
- Department of Pathogen Biology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, 510515, China
| | - Xiao-Guang Chen
- Department of Pathogen Biology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, 510515, China
| | - Jinbao Gu
- Department of Pathogen Biology, Guangdong Provincial Key Laboratory of Tropical Disease Research, School of Public Health, Southern Medical University, Guangzhou, 510515, China
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7
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Mine S, Sumitani M, Aoki F, Hatakeyama M, Suzuki MG. Effects of Functional Depletion of Doublesex on Male Development in the Sawfly, Athalia rosae. INSECTS 2021; 12:insects12100849. [PMID: 34680618 PMCID: PMC8538284 DOI: 10.3390/insects12100849] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 08/15/2021] [Revised: 09/18/2021] [Accepted: 09/20/2021] [Indexed: 01/04/2023]
Abstract
Simple Summary The sawfly, Athalia rosae, exploits a haplodiploid mode of reproduction, in which fertilized eggs develop into diploid females, whereas unfertilized eggs parthenogenetically develop into haploid males. The doublesex (dsx) gene is a well-conserved transcription factor that regulates sexual differentiation in insects. In the present study, we knocked down the A. rosae ortholog of dsx (Ardsx) during several developmental stages with repeated double-stranded RNA (dsRNA) injections. As a result, knockdown of Ardsx in haploid males caused almost complete male-to-female sex reversal, but the resulting eggs were infertile. The same knockdown approach using diploid males caused complete male-to-female sex reversal; they were able to produce fertile eggs and exhibited female behaviors. The same RNAi treatment did not affect female differentiation. These results demonstrated that dsx in the sawfly is essential for male development and its depletion caused complete male-to-female sex reversal. This is the first demonstration of functional depletion of dsx not causing intersexuality but inducing total sex reversal in males instead. Abstract The doublesex (dsx) gene, which encodes a transcription factor, regulates sexual differentiation in insects. Sex-specific splicing of dsx occurs to yield male- and female-specific isoforms, which promote male and female development, respectively. Thus, functional disruption of dsx leads to an intersexual phenotype in both sexes. We previously identified a dsx ortholog in the sawfly, Athalia rosae. Similar to dsx in other insects, dsx in the sawfly yields different isoforms in males and females as a result of alternative splicing. The sawfly exploits a haplodiploid mode of reproduction, in which fertilized eggs develop into diploid females, whereas unfertilized eggs parthenogenetically develop into haploid males. In the present study, we knocked down the A. rosae ortholog of dsx (Ardsx) during several developmental stages with repeated double-stranded RNA (dsRNA) injections. Knockdown of Ardsx via parental RNA interference (RNAi), which enables knockdown of genes in offspring embryos, led to a lack of internal and external genitalia in haploid male progeny. Additional injection of dsRNA targeting Ardsx in these animals caused almost complete male-to-female sex reversal, but the resulting eggs were infertile. Notably, the same knockdown approach using diploid males obtained by sib-crossing caused complete male-to-female sex reversal; they were morphologically and behaviorally females. The same RNAi treatment did not affect female differentiation. These results indicate that dsx in the sawfly is essential for male development and its depletion caused complete male-to-female sex reversal. This is the first demonstration of functional depletion of dsx not causing intersexuality but inducing total sex reversal in males instead.
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Affiliation(s)
- Shotaro Mine
- Department of Biosciences, Nihon University, 3-25-40 Sakurajosui, Setagaya-ku, Tokyo 156-8550, Japan;
| | - Megumi Sumitani
- Division of Biotechnology, Institute of Agrobiological Sciences, NARO, Owashi, Tsukuba 305-8634, Japan;
| | - Fugaku Aoki
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa 277-8562, Japan;
| | - Masatsugu Hatakeyama
- Division of Applied Genetics, Institute of Agrobiological Sciences, NARO, Owashi, Tsukuba 305-8634, Japan;
| | - Masataka G. Suzuki
- Department of Integrated Biosciences, Graduate School of Frontier Sciences, The University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa 277-8562, Japan;
- Correspondence: ; Tel.: +81-4-7136-3694
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femaleless Controls Sex Determination and Dosage Compensation Pathways in Females of Anopheles Mosquitoes. Curr Biol 2021; 31:1084-1091.e4. [PMID: 33417880 PMCID: PMC7955153 DOI: 10.1016/j.cub.2020.12.014] [Citation(s) in RCA: 27] [Impact Index Per Article: 9.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2020] [Revised: 11/09/2020] [Accepted: 12/11/2020] [Indexed: 01/04/2023]
Abstract
The insect sex determination and the intimately linked dosage compensation pathways represent a challenging evolutionary puzzle that has been solved only in Drosophila melanogaster. Analyses of orthologs of the Drosophila genes identified in non-drosophilid taxa1,2 revealed that evolution of sex determination pathways is consistent with a bottom-up mode,3 where only the terminal genes within the pathway are well conserved. doublesex (dsx), occupying a bottom-most position and encoding sex-specific proteins orchestrating downstream sexual differentiation processes, is an ancient sex-determining gene present in all studied species.2,4,5 With the exception of lepidopterans, its female-specific splicing is known to be regulated by transformer (tra) and its co-factor transformer-2 (tra2).6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20 Here we show that in the African malaria mosquito Anopheles gambiae, a gene, which likely arose in the Anopheles lineage and which we call femaleless (fle), controls sex determination in females by regulating splicing of dsx and fruitless (fru; another terminal gene within a branch of the sex determination pathway). Moreover, fle represents a novel molecular link between the sex determination and dosage compensation pathways. It is necessary to suppress activation of dosage compensation in females, as demonstrated by the significant upregulation of the female X chromosome genes and a correlated female-specific lethality, but no negative effect on males, in response to fle knockdown. This unexpected property, combined with a high level of conservation in sequence and function in anopheline mosquitoes, makes fle an excellent target for genetic control of all major vectors of human malaria. fle is a new sex determination pathway element conserved in Anopheles mosquitoes fle may have originated in the Anopheles lineage and is highly conserved in Anopheles fle suppresses activation of dosage compensation in females Depletion of fle transcripts is lethal or otherwise deleterious to females
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9
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Basrur NS, De Obaldia ME, Morita T, Herre M, von Heynitz RK, Tsitohay YN, Vosshall LB. Fruitless mutant male mosquitoes gain attraction to human odor. eLife 2020; 9:e63982. [PMID: 33284111 PMCID: PMC7806257 DOI: 10.7554/elife.63982] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2020] [Accepted: 11/28/2020] [Indexed: 12/27/2022] Open
Abstract
The Aedesaegypti mosquito shows extreme sexual dimorphism in feeding. Only females are attracted to and obtain a blood-meal from humans, which they use to stimulate egg production. The fruitless gene is sex-specifically spliced and encodes a BTB zinc-finger transcription factor proposed to be a master regulator of male courtship and mating behavior across insects. We generated fruitless mutant mosquitoes and showed that males failed to mate, confirming the ancestral function of this gene in male sexual behavior. Remarkably, fruitless males also gain strong attraction to a live human host, a behavior that wild-type males never display, suggesting that male mosquitoes possess the central or peripheral neural circuits required to host-seek and that removing fruitless reveals this latent behavior in males. Our results highlight an unexpected repurposing of a master regulator of male-specific sexual behavior to control one module of female-specific blood-feeding behavior in a deadly vector of infectious diseases.
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Affiliation(s)
- Nipun S Basrur
- Laboratory of Neurogenetics and Behavior, The Rockefeller UniversityNew YorkUnited States
| | - Maria Elena De Obaldia
- Laboratory of Neurogenetics and Behavior, The Rockefeller UniversityNew YorkUnited States
| | - Takeshi Morita
- Laboratory of Neurogenetics and Behavior, The Rockefeller UniversityNew YorkUnited States
| | - Margaret Herre
- Laboratory of Neurogenetics and Behavior, The Rockefeller UniversityNew YorkUnited States
- Kavli Neural Systems InstituteNew YorkUnited States
| | - Ricarda K von Heynitz
- Laboratory of Neurogenetics and Behavior, The Rockefeller UniversityNew YorkUnited States
| | - Yael N Tsitohay
- Laboratory of Neurogenetics and Behavior, The Rockefeller UniversityNew YorkUnited States
| | - Leslie B Vosshall
- Laboratory of Neurogenetics and Behavior, The Rockefeller UniversityNew YorkUnited States
- Kavli Neural Systems InstituteNew YorkUnited States
- Howard Hughes Medical InstituteNew YorkUnited States
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10
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The transformer-2 and fruitless characterisation with developmental expression profiles of sex-determining genes in Bactrocera dorsalis and B. correcta. Sci Rep 2020; 10:17938. [PMID: 33087807 PMCID: PMC7578103 DOI: 10.1038/s41598-020-74856-6] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/25/2020] [Accepted: 10/07/2020] [Indexed: 12/12/2022] Open
Abstract
Sex determination in tephritid fruit flies involves a signaling cascade of alternatively spliced genes. The Transformer (TRA) and Transformer-2 (TRA-2) complex establishes an autoregulatory loop switching sex-specific splicing of tra pre-mRNA in females. The TRA/TRA-2 complex also regulates the sex-specific splicing of downstream effector genes, doublesex (dsx) and fruitless (fru). In Ceratitis capitata, a Maleness-on the-Y (MoY) gene modulates sex-specifically spliced Cctra pre-mRNA and results in the breakdown of the Cctra autoregulatory loop in males. In this study, the tra-2 and fru genes were characterised in two key pests, Bactrocera dorsalis and B. correcta. The tra-2 genes showed high degrees of conservation among tephritids. The complex gene organisation for each of Bdfru and Bcfru were identified. There are sex-specific and non sex-specific transcripts generated by alternative promoters as found in Drosophila melanogaster and other insects. RNAi knockdown of Bdtra transcripts showed that BdTRA controls the sex-specific splicing of Bddsx and Bdfru pre-mRNAs. Developmental expression analysis shows that multiple splice variants of Bdtra and Bctra RNAs are present before and during cellular blastoderm formation and that the mature sex-specific variants become fixed later in embryogenesis. Furthermore, the BddsxM splice variants are found in early embryos at the beginning of gastulation, but BdfruM does not appear until the larval stage. We proposed that the zygotic tra loop is initiated in both female and male embryos before becoming automatised or abolished by MoY, respectively.
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Xu J, Liu W, Yang D, Chen S, Chen K, Liu Z, Yang X, Meng J, Zhu G, Dong S, Zhang Y, Zhan S, Wang G, Huang Y. Regulation of olfactory-based sex behaviors in the silkworm by genes in the sex-determination cascade. PLoS Genet 2020; 16:e1008622. [PMID: 32520935 PMCID: PMC7307793 DOI: 10.1371/journal.pgen.1008622] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/17/2020] [Revised: 06/22/2020] [Accepted: 05/04/2020] [Indexed: 11/28/2022] Open
Abstract
Insect courtship and mating depend on integration of olfactory, visual, and tactile cues. Compared to other insects, Bombyx mori, the domesticated silkworm, has relatively simple sexual behaviors as it cannot fly. Here by using CRISPR/Cas9 and electrophysiological techniques we found that courtship and mating behaviors are regulated in male silk moths by mutating genes in the sex determination cascade belonging to two conserved pathways. Loss of Bmdsx gene expression significantly reduced the peripheral perception of the major pheromone component bombykol by reducing expression of the product of the BmOR1 gene which completely blocked courtship in adult males. Interestingly, we found that mating behavior was regulated independently by another sexual differentiation gene, Bmfru. Loss of Bmfru completely blocked mating, but males displayed normal courtship behavior. Lack of Bmfru expression significantly reduced the perception of the minor pheromone component bombykal due to the down regulation of BmOR3 expression; further, functional analysis revealed that loss of the product of BmOR3 played a key role in terminating male mating behavior. Our results suggest that Bmdsx and Bmfru are at the base of the two primary pathways that regulate olfactory-based sexual behavior. The fundamental insect sexual behaviors, courtship and mating, result from successful integration of olfactory, vision, tactile and other complex innate behaviors. In the widely used insect model, Drosophila melanogaster, the sex determination cascade genes fruitless and doublesex are involved in the regulation of courtship and mating behaviors; however, little is known about the function of these sexual differentiation genes in regulating sex behaviors of Lepidoptera. Here we combine genetics and electrophysiology to investigate regulation pathway of sexual behaviors in the model lepidopteran insect, the domesticated silk moth, Bombyx mori. Our results support the presence of two genetic pathways in B. mori, named Bmdsx-BmOR1-bombykol and Bmfru-BmOR3-bombykal, which control distinct aspects of male sexual behavior that are modulated by olfaction. This is the first comprehensive report about the role of sex differentiation genes in the male sexual behavior in the silk moth.
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Affiliation(s)
- Jun Xu
- Key Laboratory of Insect Developmental and Evolutionary Biology, Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Wei Liu
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
| | - Dehong Yang
- Key Laboratory of Insect Developmental and Evolutionary Biology, Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Shuqing Chen
- Key Laboratory of Insect Developmental and Evolutionary Biology, Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Kai Chen
- Key Laboratory of Insect Developmental and Evolutionary Biology, Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Zulian Liu
- Key Laboratory of Insect Developmental and Evolutionary Biology, Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Xu Yang
- Key Laboratory of Insect Developmental and Evolutionary Biology, Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Jing Meng
- Key Laboratory of Insect Developmental and Evolutionary Biology, Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- Shanghai First Maternity and Infant Hospital, Tongji University School of Medicine, Shanghai, China
| | - Guanheng Zhu
- Education Ministry Key Laboratory of Integrated Management of Crop Disease and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Shuanglin Dong
- Education Ministry Key Laboratory of Integrated Management of Crop Disease and Pests, College of Plant Protection, Nanjing Agricultural University, Nanjing, China
| | - Yong Zhang
- Department of Biology, University of Nevada, Reno, Nevada, United States of America
| | - Shuai Zhan
- Key Laboratory of Insect Developmental and Evolutionary Biology, Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
| | - Guirong Wang
- State Key Laboratory for Biology of Plant Diseases and Insect Pests, Institute of Plant Protection, Chinese Academy of Agricultural Sciences, Beijing, China
- * E-mail: (GW); (YH)
| | - Yongping Huang
- Key Laboratory of Insect Developmental and Evolutionary Biology, Center for Excellence in Molecular Plant Sciences, Shanghai Institute of Plant Physiology and Ecology, Chinese Academy of Sciences, Shanghai, China
- * E-mail: (GW); (YH)
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12
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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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13
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McKelvey EG, Fabre CC. Recent neurogenetic findings in insect courtship behaviour. CURRENT OPINION IN INSECT SCIENCE 2019; 36:103-110. [PMID: 31546094 DOI: 10.1016/j.cois.2019.08.010] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/18/2019] [Revised: 07/30/2019] [Accepted: 08/13/2019] [Indexed: 06/10/2023]
Abstract
Insect courtship parades consist of series of innate and stereotyped behaviours that become hardwired-in during the development of the nervous system. As such, insect courtship behaviour provides an excellent model for probing the principles of neuronal assembly, which underlie patterns of behaviour. Here, we present the main advances of recent studies - in species all the way from flies to planthoppers - and we envisage how these could lead to further propitious findings.
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Affiliation(s)
- Eleanor Gz McKelvey
- University of Cambridge, Department of Zoology, Downing Street, Cambridge CB2 3EJ, United Kingdom
| | - Caroline Cg Fabre
- University of Cambridge, Department of Zoology, Downing Street, Cambridge CB2 3EJ, United Kingdom.
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14
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Watanabe T. Evolution of the neural sex-determination system in insects: does fruitless homologue regulate neural sexual dimorphism in basal insects? INSECT MOLECULAR BIOLOGY 2019; 28:807-827. [PMID: 31066110 DOI: 10.1111/imb.12590] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
In the brain of holometabolous insects such as the fruit fly Drosophila melanogaster, the fruitless gene produces sex-specific gene products under the control of the sex-specific splicing cascade and contributes to the formation of the sexually dimorphic circuits. Similar sex-specific gene products of fruitless homologues have been identified in other holometabolous insects such as mosquitoes and a parasitic wasp, suggesting the fruitless-dependent neural sex-determination system is widely conserved amongst holometabolous insects. However, it remains obscure whether the fruitless-dependent neural sex-determination system is present in basal hemimetabolous insects. To address this issue, identification, characterization, and expression analyses of the fruitless homologue were conducted in the two-spotted cricket, Gryllus bimaculatus, as a model hemimetabolous insect. The Gryllus fruitless gene encodes multiple isoforms with a unique zinc finger domain, and does not encode a sex-specific gene product. The Gryllus Fruitless protein is broadly expressed in the neurones and glial cells in the brain, and there was no prominent sex-related difference in the expression levels of Gryllus fruitless isoforms. The results suggest that the Gryllus fruitless gene is not involved in the neural sex-determination in the cricket brain.
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Affiliation(s)
- T Watanabe
- Department of Biological Sciences, Faculty of Science, Hokkaido University, Sapporo, Japan
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15
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Sherer LM, Certel SJ. The fight to understand fighting: neurogenetic approaches to the study of aggression in insects. CURRENT OPINION IN INSECT SCIENCE 2019; 36:18-24. [PMID: 31302354 PMCID: PMC6906251 DOI: 10.1016/j.cois.2019.06.004] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Revised: 05/14/2019] [Accepted: 06/12/2019] [Indexed: 06/10/2023]
Abstract
Aggression is an evolutionarily conserved behavior that evolved in the framework of defending or obtaining resources. When expressed out of context, unchecked aggression can have destructive consequences. Model systems that allow examination of distinct neuronal networks at the molecular, cellular, and circuit levels are adding immensely to our understanding of the biological basis of this behavior and should be relatable to other species up to and including man. Investigators have made particular use of insect models to both describe this quantifiable and stereotyped behavior and to manipulate genes and neuron function via numerous genetic and pharmacological tools. This review discusses recent advances in techniques that improve our ability to identify, manipulate, visualize, and compare the genes, neurons, and circuits that are required for the output of this complex and clinically relevant social behavior.
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Affiliation(s)
- Lewis M Sherer
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, United States
| | - Sarah J Certel
- Division of Biological Sciences, University of Montana, Missoula, MT 59812, United States.
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16
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Petrella V, Aceto S, Colonna V, Saccone G, Sanges R, Polanska N, Volf P, Gradoni L, Bongiorno G, Salvemini M. Identification of sex determination genes and their evolution in Phlebotominae sand flies (Diptera, Nematocera). BMC Genomics 2019; 20:522. [PMID: 31238870 PMCID: PMC6593557 DOI: 10.1186/s12864-019-5898-4] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2019] [Accepted: 06/11/2019] [Indexed: 11/10/2022] Open
Abstract
BACKGROUND Phlebotomine sand flies (Diptera, Nematocera) are important vectors of several pathogens, including Leishmania parasites, causing serious diseases of humans and dogs. Despite their importance as disease vectors, most aspects of sand fly biology remain unknown including the molecular basis of their reproduction and sex determination, aspects also relevant for the development of novel vector control strategies. RESULTS Using comparative genomics/transcriptomics data mining and transcriptional profiling, we identified the sex determining genes in phlebotomine sand flies and proposed the first model for the sex determination cascade of these insects. For all the genes identified, we produced manually curated gene models, developmental gene expression profile and performed evolutionary molecular analysis. We identified and characterized, for the first time in a Nematocera species, the transformer (tra) homolog which exhibits both conserved and novel features. The analysis of the tra locus in sand flies and its expression pattern suggest that this gene is able to autoregulate its own splicing, as observed in the fruit fly Ceratitis capitata and several other insect species. CONCLUSIONS Our results permit to fill the gap about sex determination in sand flies, contribute to a better understanding of this developmental pathway in Nematocera and open the way for the identification of sex determining orthologs in other species of this important Diptera sub-order. Furthermore, the sex determination genes identified in our work also provide the opportunity of future biotechnological applications to control natural population of sand flies, reducing their impact on public health.
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Affiliation(s)
- Valeria Petrella
- Department of Biology, University of Naples Federico II, Naples, Italy
| | - Serena Aceto
- Department of Biology, University of Naples Federico II, Naples, Italy
| | - Vincenza Colonna
- National Research Council, Institute of Genetics and Biophysics, Naples, Italy
| | - Giuseppe Saccone
- Department of Biology, University of Naples Federico II, Naples, Italy
| | - Remo Sanges
- Stazione Zoologica “Anton Dohrn”, Naples, Italy
- Department of Neuroscience, Scuola Internazionale Superiore di Studi Avanzati (SISSA), Trieste, Italy
| | - Nikola Polanska
- Department of Parasitology, Charles University, Prague, Czech Republic
| | - Petr Volf
- Department of Parasitology, Charles University, Prague, Czech Republic
| | - Luigi Gradoni
- Unit of Vector-borne Diseases, Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy
| | - Gioia Bongiorno
- Unit of Vector-borne Diseases, Department of Infectious Diseases, Istituto Superiore di Sanità, Rome, Italy
| | - Marco Salvemini
- Department of Biology, University of Naples Federico II, Naples, Italy
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17
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Li X, Jin B, Dong Y, Chen X, Tu Z, Gu J. Two of the three Transformer-2 genes are required for ovarian development in Aedes albopictus. INSECT BIOCHEMISTRY AND MOLECULAR BIOLOGY 2019; 109:92-105. [PMID: 30914323 PMCID: PMC6636634 DOI: 10.1016/j.ibmb.2019.03.008] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/02/2018] [Revised: 03/18/2019] [Accepted: 03/21/2019] [Indexed: 05/23/2023]
Abstract
In Drosophila melanogaster, transformer-2 (tra2) plays an essential role in the sex-specific splicing of doublesex (dsx) and fruitless (fru), two key transcription factor genes that program sexual differentiation and regulate sexual behavior. In the present study, the sequences and expression profiles of three tra2 (Aalbtra2) genes in the Asian tiger mosquito, Aedes albopictus (Ae. albopictus) were characterized. Phylogenetic analysis revealed that these paralogs resulted from two duplication events. The first occurred in the common ancestor of Culicidae, giving rise to the tra2-α and tra2-β clades that are found across divergent mosquito genera, including Aedes, Culex, and Anopheles. The second occurred within the tra2-α clade, giving rise to tra2-γ in Ae. albopictus. In addition to the conserved RNA recognition motif (RRM), arginine-rich/serine-rich regions (RS domains) and a linker region, a glycine-rich region located between the RRM and RS2 was observed in Tra2-α and Tra2-γ of Ae. albopictus that has not yet been described in the Tra2 proteins of dipteran insects. Quantitative real-time PCR detected relatively high levels of transcripts from all three tra2 paralogs in 0-2 h embryos, suggesting maternal deposition of these transcripts. All three Aalbtra2 genes were highly expressed in the ovary, while Aalbtra2-β was also highly expressed in the testis. RNAi-mediated knockdown of any or all Aalbtra2 genes did not result in an obvious switch of the sex-specificity in dsx and fru splicing in the whole-body samples. However, knockdown of transcripts from all three tra2 genes significantly reduced the female isoform of dsx mRNA and increased the male isoform of the dsx mRNA in both the ovary and the fat body in adult females. Furthermore, knockdown of either Aalbtra2-α or Aalbtra2-γ or all three Aalbtra2 led to a decrease in ovariole number and ovary size after a blood meal. Taken together, these results indicate that two of the three tra2 genes affect female ovarian development.
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Affiliation(s)
- Xiaocong Li
- Guangdong Provincial Key Laboratory of Tropical Disease Research, Department of Pathogen Biology, School of Public Health, Southern Medical University, Guangzhou, Guangdong, 510515, China
| | - Binbin Jin
- Guangdong Provincial Key Laboratory of Tropical Disease Research, Department of Pathogen Biology, School of Public Health, Southern Medical University, Guangzhou, Guangdong, 510515, China
| | - Yunqiao Dong
- Reproductive Medical Centre of Guangdong Women and Children Hospital, Guangzhou, Guangdong, 511442, China
| | - Xiaoguang Chen
- Guangdong Provincial Key Laboratory of Tropical Disease Research, Department of Pathogen Biology, School of Public Health, Southern Medical University, Guangzhou, Guangdong, 510515, China.
| | - Zhijian Tu
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, 24060, USA
| | - Jinbao Gu
- Guangdong Provincial Key Laboratory of Tropical Disease Research, Department of Pathogen Biology, School of Public Health, Southern Medical University, Guangzhou, Guangdong, 510515, China.
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18
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Gomulski LM, Mariconti M, Di Cosimo A, Scolari F, Manni M, Savini G, Malacrida AR, Gasperi G. The Nix locus on the male-specific homologue of chromosome 1 in Aedes albopictus is a strong candidate for a male-determining factor. Parasit Vectors 2018; 11:647. [PMID: 30583734 PMCID: PMC6304787 DOI: 10.1186/s13071-018-3215-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
Background Global concern over the rapid expansion of the Asian tiger mosquito, Aedes albopictus, and its vector competence has highlighted an urgent need to improve currently available population control methods, like the Sterile Insect Technique. Knowledge of the sex determination cascade is a prerequisite for the development of early-stage sexing systems. To this end, we have characterised the putative sex determination gene, Nix, in this species. In Aedes species the chromosome complement consists of three pairs of chromosomes. The sex determination alleles are linked to the smallest homomorphic chromosome. Results We identified the male-specific chromosome 1 of Ae. albopictus that carries the putative male-determining gene Nix. We have also characterised the complete genomic sequence of the Nix gene which is composed of two exons and a short intron. The gene displays different levels of intron retention during development. Comparison of DNA sequences covering most of the Nix gene from individuals across the species range revealed no polymorphism. Conclusions Our characterisation of the Nix gene in Ae. albopictus represents an initial step in the analysis of the sex determination cascade in this species. We found evidence of intron retention (IR) in Nix. IR might play a role in regulating the expression of Nix during development. Our results provide the basis for the development of new genetic control strategies. Electronic supplementary material The online version of this article (10.1186/s13071-018-3215-8) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Ludvik M Gomulski
- Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, Pavia, Italy
| | - Marina Mariconti
- Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, Pavia, Italy
| | - Alessandro Di Cosimo
- Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, Pavia, Italy
| | - Francesca Scolari
- Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, Pavia, Italy
| | - Mosè Manni
- Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, Pavia, Italy.,Department of Genetic Medicine and Development, University of Geneva Medical School, and Swiss Institute of Bioinformatics, Geneva, Switzerland
| | - Grazia Savini
- Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, Pavia, Italy
| | - Anna R Malacrida
- Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, Pavia, Italy
| | - Giuliano Gasperi
- Department of Biology and Biotechnology "L. Spallanzani", University of Pavia, Pavia, Italy.
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19
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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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20
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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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21
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Mysore K, Li P, Duman-Scheel M. Identification of Aedes aegypti cis-regulatory elements that promote gene expression in olfactory receptor neurons of distantly related dipteran insects. Parasit Vectors 2018; 11:406. [PMID: 29996889 PMCID: PMC6042464 DOI: 10.1186/s13071-018-2982-6] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2018] [Accepted: 06/27/2018] [Indexed: 12/25/2022] Open
Abstract
Background Sophisticated tools for manipulation of gene expression in select neurons, including neurons that regulate sexually dimorphic behaviors, are increasingly available for analysis of genetic model organisms. However, we lack comparable genetic tools for analysis of non-model organisms, including Aedes aegypti, a vector mosquito which displays sexually dimorphic behaviors that contribute to pathogen transmission. Formaldehyde-assisted isolation of regulatory elements followed by sequencing (FAIRE-seq) recently facilitated genome-wide discovery of putative A. aegypti cis-regulatory elements (CREs), many of which could be used to manipulate gene expression in mosquito neurons and other tissues. The goal of this investigation was to identify FAIRE DNA elements that promote gene expression in the olfactory system, a tissue of vector importance. Results Eight A. aegypti CREs that promote gene expression in antennal olfactory receptor neurons (ORNs) were identified in a Drosophila melanogaster transgenic reporter screen. Four CREs identified in the screen were cloned upstream of GAL4 in a transgenic construct that is compatible with transformation of a variety of insect species. These constructs, which contained FAIRE DNA elements associated with the A. aegypti odorant coreceptor (orco), odorant receptor 1 (Or1), odorant receptor 8 (Or8) and fruitless (fru) genes, were used for transformation of A. aegypti. Six A. aegypti strains, including strains displaying transgene expression in all ORNs, subsets of these neurons, or in a sex-specific fashion, were isolated. The CREs drove transgene expression in A. aegypti that corresponded to endogenous gene expression patterns of the orco, Or1, Or8 and fru genes in the mosquito antenna. CRE activity in A. aegypti was found to be comparable to that observed in D. melanogaster reporter assays. Conclusions These results provide further evidence that FAIRE-seq, which can be paired with D. melanogaster reporter screening to test FAIRE DNA element activity in select tissues, is a useful method for identification of mosquito cis-regulatory elements. These findings expand the genetic toolkit available for the study of Aedes neurobiology. Moreover, given that the CREs drive comparable olfactory neural expression in both A. aegypti and D. melanogaster, it is likely that they may function similarly in multiple dipteran insects, including other disease vector mosquito species.
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Affiliation(s)
- Keshava Mysore
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, 1234 Notre Dame Avenue, Raclin-Carmichael Hall, South Bend, IN, 46617, USA.,The University of Notre Dame Eck Institute for Global Health, Notre Dame, IN, 46556, USA
| | - Ping Li
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, 1234 Notre Dame Avenue, Raclin-Carmichael Hall, South Bend, IN, 46617, USA.,The University of Notre Dame Eck Institute for Global Health, Notre Dame, IN, 46556, USA
| | - Molly Duman-Scheel
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, 1234 Notre Dame Avenue, Raclin-Carmichael Hall, South Bend, IN, 46617, USA. .,The University of Notre Dame Eck Institute for Global Health, Notre Dame, IN, 46556, USA. .,Department of Biological Sciences, The University of Notre Dame, Notre Dame, IN, 46556, USA.
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Tanaka A, Aoki F, Suzuki MG. Conserved Domains in the Transformer Protein Act Complementary to Regulate Sex-Specific Splicing of Its Own Pre-mRNA. Sex Dev 2018; 12:180-190. [PMID: 29804107 DOI: 10.1159/000489444] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 11/29/2017] [Indexed: 01/13/2023] Open
Abstract
The transformer (tra) gene, which is a female-determining master gene in the housefly Musca domestica, acts as a memory device for sex determination via its auto-regulatory function, i.e., through the contribution of the TRA protein to female-specific splicing of its own pre-mRNA. The TRA protein contains 4 small domains that are specifically conserved among TRA proteins (domains 1-4). Domain 2, also named TRA-CAM domain, is the most conserved, but its function remains unknown. To examine whether these domains are involved in the auto-regulatory function, we performed in vitro splicing assays using a tra minigene containing a partial genomic sequence of the M. domestica tra (Mdtra) gene. Co-transfection of the Mdtra minigene and an MdTRA protein expression vector into cultured insect cells strongly induced female-specific splicing of the minigene. A series of deletion mutation analyses demonstrated that these domains act complementarily to induce female-specific splicing. Domain 1 and the TRA-CAM domain were necessary for the female-specific splicing when the MdTRA protein lacked both domains 3 and 4. In this situation, mutation of the well-conserved 3 amino acids (GEG) in the TRA-CAM domain significantly reduced the female-specific splicing activity of MdTRA. GST-pull down analyses demonstrated that the MdTRA protein specifically enriched on the male-specific exonic region (exon 2b), which contains the putative TRA/TRA-2 binding sites, and that the GEG mutation disrupts this enrichment. Since the MdTRA protein interacts with its own pre-mRNA through TRA-2, our findings suggest that the conserved amino acid residues in the TRA-CAM domain may be crucial for the interaction between MdTRA and TRA-2, enhancing MdTRA recruitment on its pre-mRNA to induce female-specific splicing of tra in the housefly.
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Sex Determination Cascade in Insects: A Great Treasure House of Alternative Splicing. DIVERSITY AND COMMONALITY IN ANIMALS 2018. [DOI: 10.1007/978-4-431-56609-0_13] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
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Campbell CL, Dickson LB, Lozano-Fuentes S, Juneja P, Jiggins FM, Black WC. Alternative patterns of sex chromosome differentiation in Aedes aegypti (L). BMC Genomics 2017; 18:943. [PMID: 29202694 PMCID: PMC5716240 DOI: 10.1186/s12864-017-4348-4] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Accepted: 11/23/2017] [Indexed: 12/16/2022] Open
Abstract
Background Some populations of West African Aedes aegypti, the dengue and zika vector, are reproductively incompatible; our earlier study showed that divergence and rearrangements of genes on chromosome 1, which bears the sex locus (M), may be involved. We also previously described a proposed cryptic subspecies SenAae (PK10, Senegal) that had many more high inter-sex FST genes on chromosome 1 than did Ae.aegypti aegypti (Aaa, Pai Lom, Thailand). The current work more thoroughly explores the significance of those findings. Results Intersex standardized variance (FST) of single nucleotide polymorphisms (SNPs) was characterized from genomic exome capture libraries of both sexes in representative natural populations of Aaa and SenAae. Our goal was to identify SNPs that varied in frequency between males and females, and most were expected to occur on chromosome 1. Use of the assembled AaegL4 reference alleviated the previous problem of unmapped genes. Because the M locus gene nix was not captured and not present in AaegL4, the male-determining locus, per se, was not explored. Sex-associated genes were those with FST values ≥ 0.100 and/or with increased expected heterozygosity (Hexp, one-sided T-test, p < 0.05) in males. There were 85 genes common to both collections with high inter-sex FST values; all genes but one were located on chromosome 1. Aaa showed the expected cluster of high inter-sex FST genes proximal to the M locus, whereas SenAae had inter-sex FST genes along the length of chromosome 1. In addition, the Aaa M-locus proximal region showed increased Hexp levels in males, whereas SenAae did not. In SenAae, chromosomal rearrangements and subsequent suppressed recombination may have accelerated X-Y differentiation. Conclusions The evidence presented here is consistent with differential evolution of proto-Y chromosomes in Aaa and SenAae. Electronic supplementary material The online version of this article (doi: 10.1186/s12864-017-4348-4) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Corey L Campbell
- Department of Microbiology, Immunology and Pathology, Colorado State University, Campus Delivery 1692, Fort Collins, CO, 80523, USA.
| | - Laura B Dickson
- Department of Microbiology, Immunology and Pathology, Colorado State University, Campus Delivery 1692, Fort Collins, CO, 80523, USA
| | - Saul Lozano-Fuentes
- Department of Microbiology, Immunology and Pathology, Colorado State University, Campus Delivery 1692, Fort Collins, CO, 80523, USA
| | - Punita Juneja
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK
| | - Francis M Jiggins
- Department of Genetics, University of Cambridge, Downing Street, Cambridge, CB2 3EH, UK
| | - William C Black
- Department of Microbiology, Immunology and Pathology, Colorado State University, Campus Delivery 1692, Fort Collins, CO, 80523, USA
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Li P, Liu Y, Luo D, Song C, Cui Z. Two spliced isoforms of the sex-determination gene fruitless in the Chinese mitten crab Eriocheir sinensis. Comp Biochem Physiol B Biochem Mol Biol 2017; 208-209:75-83. [PMID: 28438684 DOI: 10.1016/j.cbpb.2017.04.008] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2017] [Revised: 04/11/2017] [Accepted: 04/17/2017] [Indexed: 01/06/2023]
Abstract
The fruitless (fru) gene plays an important role in the sex determination pathway and courtship behavior of Drosophila melanogaster. In the present study, two fru isoforms (Esfru1 and Esfru2) were identified from the Chinese mitten crab Eriocheir sinensis. Sequence analysis showed that Esfru1 and Esfru2 were encoded by the same genomic locus and generated by alternative splicing of pre-mRNA. Esfru1 had all introns completely spliced out, while Esfru2 had a longer exon1 with an additional 78bp sequence. They both contained a conserved BTB domain which was also found in D. melanogaster Fru isoforms. Analysis on temporal expression profiles of Esfru1-2 (a common region of Esfru1 and Esfru2) and Esfru2 (a specific region of Esfru2) showed that they expressed in similar patterns during embryonic development but in different patterns during larval development. The expression of Esfru1-2 decreased gradually from zoea III stage, however, Esfru2 increased from zoea IV stage and reached the peak at megalopa stage. Expression distribution in tissues and in situ hybridization analysis revealed that they showed sexually dimorphic expression in gonads, hepatopancreas and brains. Esfru1-2 showed significantly higher expression in female gonads and hepatopancreas than in males, but highly expressed in male brains than that in females. Interestingly, Esfru2 was displayed in a male-specific manner in each tissue, especially in gonads and hepatopancreas. Our results indicate that Esfru1 might be involved in both sexual brain neuronal structure development and related to female-specific character development. Esfru2 may participate in male-specific character development. This is the first report that characterizes two spliced variants of fru in crustaceans and provides basic information for further functional studies of the crab sex-determination mechanism.
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Affiliation(s)
- Peiyao Li
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China; University of Chinese Academy of Sciences, Beijing 100049, China
| | - Yuan Liu
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China.
| | - Danli Luo
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
| | - Chengwen Song
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China
| | - Zhaoxia Cui
- Key Laboratory of Experimental Marine Biology, Institute of Oceanology, Chinese Academy of Sciences, Qingdao 266071, China; Laboratory for Marine Biology and Biotechnology, Qingdao National Laboratory for Marine Science and Technology, Qingdao 266071, China.
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Criscione F, Qi Y, Tu Z. GUY1 confers complete female lethality and is a strong candidate for a male-determining factor in Anopheles stephensi. eLife 2016; 5. [PMID: 27644420 PMCID: PMC5061544 DOI: 10.7554/elife.19281] [Citation(s) in RCA: 42] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Accepted: 09/12/2016] [Indexed: 12/02/2022] Open
Abstract
Despite their importance in sexual differentiation and reproduction, Y chromosome genes are rarely described because they reside in repeat-rich regions that are difficult to study. Here, we show that Guy1, a unique Y chromosome gene of a major urban malaria mosquito Anopheles stephensi, confers 100% female lethality when placed on the autosomes. We show that the small GUY1 protein (56 amino acids in length) causes female lethality and that males carrying the transgene are reproductively more competitive than their non-transgenic siblings under laboratory conditions. The GUY1 protein is a primary signal from the Y chromosome that affects embryonic development in a sex-specific manner. Our results have demonstrated, for the first time in mosquitoes, the feasibility of stable transgenic manipulation of sex ratios using an endogenous gene from the male-determining chromosome. These results provide insights into the elusive M factor and suggest exciting opportunities to reduce mosquito populations and disease transmission. DOI:http://dx.doi.org/10.7554/eLife.19281.001 Much like humans, Anopheles mosquitoes have a pair of sex chromosomes that determine whether they are male or female: females have two X chromosomes, while males have an X and a Y. Genetic evidence has indicated that there is a dominant male-determining factor on the Y chromosome that acts as a master switch to cause mosquitoes to develop into males. Mosquitoes that lack a Y chromosome, and hence the male-determining factor, therefore develop into the default female sex. Because only female mosquitoes feed on blood and transmit disease-causing microbes – including those that cause malaria – there is strong interest in identifying the male-determining factor. Introducing this gene into females could allow mosquito sex ratios to be manipulated towards the harmless non-biting males. In 2013, a study of male Anopheles stephensi mosquitoes identified a gene called Guy1 that is only found on the Y chromosome. Criscione et al. – who were involved in the 2013 study – now show that female A. stephensi mosquitoes die when the Guy1 gene is placed on their non-sex chromosomes. Further investigation confirmed that the protein produced from the Guy1 gene kills the females. This protein is an initiating signal that affects embryonic development in a sex-specific manner, making it a strong candidate to be the male determining factor in A. stephensi. This is consistent with previous reports in which the master switches of sex determination could be manipulated to kill specific sexes in fruit flies and nematode worms. Criscione et al. also found that males that carry the inserted Guy1 gene on their non-sex chromosomes – and so could potentially pass it on to both male and female offspring – are reproductively more competitive than their non-modified siblings under laboratory conditions. As the resulting female offspring would not survive, it is thus feasible, in principle, to genetically manipulate the sex ratio of the mosquitoes. A future challenge will be to identify how the protein encoded by the Guy1 gene acts to kill female mosquitoes. This knowledge will help to investigate the feasibility of using genetically modified mosquitoes to reduce Anopheles populations in order to control malaria. DOI:http://dx.doi.org/10.7554/eLife.19281.002
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Affiliation(s)
- Frank Criscione
- Department of Biochemistry, Virginia Tech, Blacksburg, United States
| | - Yumin Qi
- Department of Biochemistry, Virginia Tech, Blacksburg, United States
| | - Zhijian Tu
- Department of Biochemistry, Virginia Tech, Blacksburg, United States
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Adelman ZN, Tu Z. Control of Mosquito-Borne Infectious Diseases: Sex and Gene Drive. Trends Parasitol 2016; 32:219-229. [PMID: 26897660 DOI: 10.1016/j.pt.2015.12.003] [Citation(s) in RCA: 65] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/14/2015] [Revised: 12/01/2015] [Accepted: 12/04/2015] [Indexed: 01/23/2023]
Abstract
Sterile male releases have successfully reduced local populations of the dengue vector, Aedes aegypti, but challenges remain in scale and in separating sexes before release. The recent discovery of the first mosquito male determining factor (M factor) will facilitate our understanding of the genetic programs that initiate sexual development in mosquitoes. Manipulation of the M factor and possible intermediary factors may result in female-to-male conversion or female killing, enabling efficient sex separation and effective reduction of target mosquito populations. Given recent breakthroughs in the development of CRISPR-Cas9 reagents as a source of gene drive, more advanced technologies at driving maleness, the ultimate disease refractory phenotype, become possible and may represent efficient and self-limiting methods to control mosquito populations.
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Affiliation(s)
- Zach N Adelman
- Department of Entomology, Virginia Tech, Blacksburg, VA, USA; Fralin Life Science Institute, Virginia Tech, Blacksburg, VA, USA.
| | - Zhijian Tu
- Fralin Life Science Institute, Virginia Tech, Blacksburg, VA, USA; Department of Biochemistry, Virginia Tech, Blacksburg, VA, USA.
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Hoang KP, Teo TM, Ho TX, Le VS. Mechanisms of sex determination and transmission ratio distortion in Aedes aegypti. Parasit Vectors 2016; 9:49. [PMID: 26818000 PMCID: PMC4730765 DOI: 10.1186/s13071-016-1331-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/21/2015] [Accepted: 01/20/2016] [Indexed: 01/13/2023] Open
Abstract
Background More effective mosquito control strategies are urgently required due to the increasing prevalence of insecticide resistance. The sterile insect technique (SIT) and the release of insects carrying a dominant lethal allele (RIDL) are two proposed methods for environmentally-friendly, species-targeted population control. These methods may be more suitable for developing countries if producers reduce the cost of rearing insects. The cost of control programs could be reduced by producing all-male mosquito populations to circumvent the isolation of females before release without reducing male mating competitiveness caused by transgenes. Results An RNAi construct targeting the RNA recognition motif of the Aedes aegypti transformer-2 (tra-2) gene does not trigger female-to-male sex conversion as commonly observed among dipterous insects. Instead, homozygous insects show greater mortality among m-chromosome-bearing sperm and mm zygotes, yielding up to 100 % males in the subsequent generations. The performance of transgenic males was not significantly different to wild-type males in narrow-cage competitive mating experiments. Conclusion Our data provide preliminary evidence that the knockdown of Ae. aegypti tra-2 gene expression causes segregation distortion acting at the level of gametic function, which is reinforced by sex-specific zygotic lethality. This finding could promote the development of new synthetic sex distorter systems for the production of genetic sexing mosquito strains. Electronic supplementary material The online version of this article (doi:10.1186/s13071-016-1331-x) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Kim Phuc Hoang
- University of Engineering and Technology, Vietnam National University, Hanoi, 144 Xuan Thuy, Cau Giay, 10000, Hanoi, Vietnam.
| | - Tze Min Teo
- Advanced Agriecological Research Sdn. Bhd, No. 11 Jalan Teknologi 3/6, 47810, Petaling Jaya, Selangor, Malaysia.
| | - Thien Xuan Ho
- Department of Plant Pathology, University of Arkansas, 495 N Campus Drive, Fayetteville, AR, 72701, USA.
| | - Vinh Sy Le
- University of Engineering and Technology, Vietnam National University, Hanoi, 144 Xuan Thuy, Cau Giay, 10000, Hanoi, Vietnam.
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Abstract
Sexual dimorphism, a poorly understood but crucial aspect of vector mosquito biology, encompasses sex-specific physical, physiological, and behavioral traits related to mosquito reproduction. The study of mosquito sexual dimorphism has largely focused on analysis of the differences between adult female and male mosquitoes, particularly with respect to sex-specific behaviors related to disease transmission. However, sexually dimorphic behaviors are the products of differential gene expression that initiates during development and therefore must also be studied during development. Recent technical advancements are facilitating functional genetic studies in the dengue vector Aedes aegypti, an emerging model for mosquito development. These methodologies, many of which could be extended to other non-model insect species, are facilitating analysis of the development of sexual dimorphism in neural tissues, particularly the olfactory system. These studies are providing insight into the neurodevelopmental genetic basis for sexual dimorphism in vector mosquitoes.
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Affiliation(s)
- Molly Duman-Scheel
- Department of Medical and Molecular Genetics, Indiana University School of Medicine, South Bend, Indiana, USA; Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana, USA; Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, USA
| | - Zainulabeuddin Syed
- Eck Institute for Global Health, University of Notre Dame, Notre Dame, Indiana, USA; Department of Biological Sciences, University of Notre Dame, Notre Dame, Indiana, USA
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30
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Hall AB, Basu S, Jiang X, Qi Y, Timoshevskiy VA, Biedler JK, Sharakhova MV, Elahi R, Anderson MAE, Chen XG, Sharakhov IV, Adelman ZN, Tu Z. SEX DETERMINATION. A male-determining factor in the mosquito Aedes aegypti. Science 2015; 348:1268-70. [PMID: 25999371 DOI: 10.1126/science.aaa2850] [Citation(s) in RCA: 194] [Impact Index Per Article: 21.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2014] [Accepted: 05/07/2015] [Indexed: 12/27/2022]
Abstract
Sex determination in the mosquito Aedes aegypti is governed by a dominant male-determining factor (M factor) located within a Y chromosome-like region called the M locus. Here, we show that an M-locus gene, Nix, functions as an M factor in A. aegypti. Nix exhibits persistent M linkage and early embryonic expression, two characteristics required of an M factor. Nix knockout with clustered regularly interspaced short palindromic repeats (CRISPR)-Cas9 resulted in largely feminized genetic males and the production of female isoforms of two key regulators of sexual differentiation: doublesex and fruitless. Ectopic expression of Nix resulted in genetic females with nearly complete male genitalia. Thus, Nix is both required and sufficient to initiate male development. This study provides a foundation for mosquito control strategies that convert female mosquitoes into harmless males.
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Affiliation(s)
- Andrew Brantley Hall
- Interdisciplinary PhD Program in Genetics, Bioinformatics, and Computational Biology, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, VA, USA. Department of Biochemistry, Virginia Tech, Blacksburg, VA, USA. Fralin Life Science Institute, Virginia Tech, Blacksburg, VA, USA
| | - Sanjay Basu
- Fralin Life Science Institute, Virginia Tech, Blacksburg, VA, USA. Department of Entomology, Virginia Tech, Blacksburg, VA, USA
| | - Xiaofang Jiang
- Interdisciplinary PhD Program in Genetics, Bioinformatics, and Computational Biology, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, VA, USA. Department of Biochemistry, Virginia Tech, Blacksburg, VA, USA. Fralin Life Science Institute, Virginia Tech, Blacksburg, VA, USA
| | - Yumin Qi
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, USA. Fralin Life Science Institute, Virginia Tech, Blacksburg, VA, USA
| | - Vladimir A Timoshevskiy
- Fralin Life Science Institute, Virginia Tech, Blacksburg, VA, USA. Department of Entomology, Virginia Tech, Blacksburg, VA, USA
| | - James K Biedler
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, USA. Fralin Life Science Institute, Virginia Tech, Blacksburg, VA, USA
| | - Maria V Sharakhova
- Fralin Life Science Institute, Virginia Tech, Blacksburg, VA, USA. Department of Entomology, Virginia Tech, Blacksburg, VA, USA
| | - Rubayet Elahi
- Department of Biochemistry, Virginia Tech, Blacksburg, VA, USA
| | - Michelle A E Anderson
- Fralin Life Science Institute, Virginia Tech, Blacksburg, VA, USA. Department of Entomology, Virginia Tech, Blacksburg, VA, USA
| | - Xiao-Guang Chen
- School of Public Health and Tropical Medicine, Southern Medical University, Guangdong, People's Republic of China
| | - Igor V Sharakhov
- Interdisciplinary PhD Program in Genetics, Bioinformatics, and Computational Biology, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, VA, USA. Fralin Life Science Institute, Virginia Tech, Blacksburg, VA, USA. Department of Entomology, Virginia Tech, Blacksburg, VA, USA
| | - Zach N Adelman
- Interdisciplinary PhD Program in Genetics, Bioinformatics, and Computational Biology, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, VA, USA. Fralin Life Science Institute, Virginia Tech, Blacksburg, VA, USA. Department of Entomology, Virginia Tech, Blacksburg, VA, USA.
| | - Zhijian Tu
- Interdisciplinary PhD Program in Genetics, Bioinformatics, and Computational Biology, Virginia Polytechnic Institute and State University (Virginia Tech), Blacksburg, VA, USA. Department of Biochemistry, Virginia Tech, Blacksburg, VA, USA. Fralin Life Science Institute, Virginia Tech, Blacksburg, VA, USA.
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Silencing the buzz: a new approach to population suppression of mosquitoes by feeding larvae double-stranded RNAs. Parasit Vectors 2015; 8:96. [PMID: 25880645 PMCID: PMC4331333 DOI: 10.1186/s13071-015-0716-6] [Citation(s) in RCA: 86] [Impact Index Per Article: 9.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/07/2015] [Accepted: 02/05/2015] [Indexed: 12/22/2022] Open
Abstract
BACKGROUND Mosquito-borne diseases threaten over half the world's human population, making the need for environmentally-safe mosquito population control tools critical. The sterile insect technique (SIT) is a biological control method that can reduce pest insect populations by releasing a large number of sterile males to compete with wild males for female mates to reduce the number of progeny produced. Typically, males are sterilized using radiation, but such methods can reduce their mating competitiveness. The method is also most effective if only males are produced, but this requires the development of effective sex-sorting methods. Recent efforts to use transgenic methods to produce sterile male mosquitoes have increased interest in using SIT to control some of our most serious disease vectors, but the release of genetically modified mosquitoes will undoubtedly encounter considerable delays as regulatory agencies deal with safety issues and public concerns. METHODS Testis genes in the dengue vector Aedes aegypti were identified using a suppression subtractive hybridization technique. Mosquito larvae were fed double-stranded RNAs (dsRNAs) that targeted both the testis genes and a female sex determination gene (doublesex) to induce RNA interference (RNAi) -mediated sterility and inhibition of female development. Fertility and mating competiveness of the treated males were assessed in small-scale mating competition experiments. RESULTS Feeding mosquito larvae dsRNAs targeting testis genes produced adult males with greatly reduced fertility; several dsRNAs produced males that were highly effective in competing for mates. RNAi-mediated knockdown of the female-specific isoform of doublesex was also effective in producing a highly male-biased population of mosquitoes, thereby overcoming the need to sex-sort insects before release. CONCLUSIONS The sequence-specific gene-silencing mechanism of this RNAi technology renders it adaptable for species-specific application across numerous insect species. We envisage its use for traditional large-scale reared releases of mosquitoes and other pest insects, although the technology might also have potential for field-based control of mosquitoes where eggs deposited into a spiked larval site lead to the release of new sterile males.
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Examination of the genetic basis for sexual dimorphism in the Aedes aegypti (dengue vector mosquito) pupal brain. Biol Sex Differ 2014; 5:10. [PMID: 25729562 PMCID: PMC4342991 DOI: 10.1186/s13293-014-0010-x] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 04/04/2014] [Accepted: 07/22/2014] [Indexed: 12/23/2022] Open
Abstract
Background Most animal species exhibit sexually dimorphic behaviors, many of which are linked to reproduction. A number of these behaviors, including blood feeding in female mosquitoes, contribute to the global spread of vector-borne illnesses. However, knowledge concerning the genetic basis of sexually dimorphic traits is limited in any organism, including mosquitoes, especially with respect to differences in the developing nervous system. Methods Custom microarrays were used to examine global differences in female vs. male gene expression in the developing pupal head of the dengue vector mosquito, Aedes aegypti. The spatial expression patterns of a subset of differentially expressed transcripts were examined in the developing female vs. male pupal brain through in situ hybridization experiments. Small interfering RNA (siRNA)-mediated knockdown studies were used to assess the putative role of Doublesex, a terminal component of the sex determination pathway, in the regulation of sex-specific gene expression observed in the developing pupal brain. Results Transcripts (2,527), many of which were linked to proteolysis, the proteasome, metabolism, catabolic, and biosynthetic processes, ion transport, cell growth, and proliferation, were found to be differentially expressed in A. aegypti female vs. male pupal heads. Analysis of the spatial expression patterns for a subset of dimorphically expressed genes in the pupal brain validated the data set and also facilitated the identification of brain regions with dimorphic gene expression. In many cases, dimorphic gene expression localized to the optic lobe. Sex-specific differences in gene expression were also detected in the antennal lobe and mushroom body. siRNA-mediated gene targeting experiments demonstrated that Doublesex, a transcription factor with consensus binding sites located adjacent to many dimorphically expressed transcripts that function in neural development, is required for regulation of sex-specific gene expression in the developing A. aegypti brain. Conclusions These studies revealed sex-specific gene expression profiles in the developing A. aegypti pupal head and identified Doublesex as a key regulator of sexually dimorphic gene expression during mosquito neural development.
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Geuverink E, Beukeboom LW. Phylogenetic distribution and evolutionary dynamics of the sex determination genes doublesex and transformer in insects. Sex Dev 2013; 8:38-49. [PMID: 24401160 DOI: 10.1159/000357056] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022] Open
Abstract
Sex determination in insects is characterized by a gene cascade that is conserved at the bottom but contains diverse primary signals at the top. The bottom master switch gene doublesex is found in all insects. Its upstream regulator transformer is present in the orders Hymenoptera, Coleoptera and Diptera, but has thus far not been found in Lepidoptera and in the basal lineages of Diptera. transformer is presumed to be ancestral to the holometabolous insects based on its shared domains and conserved features of autoregulation and sex-specific splicing. We interpret that its absence in basal lineages of Diptera and its order-specific conserved domains indicate multiple independent losses or recruitments into the sex determination cascade. Duplications of transformer are found in derived families within the Hymenoptera, characterized by their complementary sex determination mechanism. As duplications are not found in any other insect order, they appear linked to the haplodiploid reproduction of the Hymenoptera. Further phylogenetic analyses combined with functional studies are needed to understand the evolutionary history of the transformer gene among insects.
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Affiliation(s)
- E Geuverink
- Evolutionary Genetics, Center for Ecological and Evolutionary Studies, University of Groningen, Groningen, The Netherlands
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34
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The evolution of novelty in conserved genes; evidence of positive selection in the Drosophila fruitless gene is localised to alternatively spliced exons. Heredity (Edinb) 2013; 112:300-6. [PMID: 24149653 DOI: 10.1038/hdy.2013.106] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2013] [Revised: 08/30/2013] [Accepted: 09/24/2013] [Indexed: 11/08/2022] Open
Abstract
There has been much debate concerning whether cis-regulatory or coding changes are more likely to produce evolutionary innovation or adaptation in gene function, but an additional complication is that some genes can dramatically diverge through alternative splicing, increasing the diversity of gene function within a locus. The fruitless gene is a major transcription factor with a wide range of pleiotropic functions, including a fundamental conserved role in sexual differentiation, species-specific morphology and an important influence on male sexual behaviour. Here, we examine the structure of fruitless in multiple species of Drosophila, and determine the patterns of selective constraint acting across the coding region. We found that the pattern of selection, estimated from the ratio of non-synonymous to synonymous substitutions, varied considerably across the gene, with most regions of the gene evolutionarily conserved but with several regions showing evidence of divergence as a result of positive selection. The regions that showed evidence of positive selection were found to be localised to relatively consistent regions across multiple speciation events, and are associated with alternative splicing. Alternative splicing may thus provide a route to gene diversification in key regulatory loci.
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Meier N, Käppeli SC, Hediger Niessen M, Billeter JC, Goodwin SF, Bopp D. Genetic control of courtship behavior in the housefly: evidence for a conserved bifurcation of the sex-determining pathway. PLoS One 2013; 8:e62476. [PMID: 23630634 PMCID: PMC3632534 DOI: 10.1371/journal.pone.0062476] [Citation(s) in RCA: 27] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/28/2012] [Accepted: 03/21/2013] [Indexed: 12/30/2022] Open
Abstract
In Drosophila melanogaster, genes of the sex-determination hierarchy orchestrate the development and differentiation of sex-specific tissues, establishing sex-specific physiology and neural circuitry. One of these sex-determination genes, fruitless (fru), plays a key role in the formation of neural circuits underlying Drosophila male courtship behavior. Conservation of fru gene structure and sex-specific expression has been found in several insect orders, though it is still to be determined whether a male courtship role for the gene is employed in these species due to the lack of mutants and homologous experimental evidence. We have isolated the fru ortholog (Md-fru) from the common housefly, Musca domestica, and show the gene's conserved genomic structure. We demonstrate that male-specific Md-fru transcripts arise by conserved mechanisms of sex-specific splicing. Here we show that Md-fru, is similarly involved in controlling male courtship behavior. A male courtship behavioral function for Md-fru was revealed by the behavioral and neuroanatomical analyses of a hypomorphic allele, Md-tra(man) , which specifically disrupted the expression of Md-fru in males, leading to severely impaired male courtship behavior. In line with a role in nervous system development, we found that expression of Md-fru was confined to neural tissues in the brain, most prominently in optic neuropil and in peripheral sensory organs. We propose that, like in Drosophila, overt sexual differentiation of the housefly depends on a sex-determining pathway that bifurcates downstream of the Md-tra gene to coordinate dimorphic development of non-neuronal tissues mediated by Md-dsx with that of neuronal tissues largely mediated by Md-fru.
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Affiliation(s)
- Nicole Meier
- Institute of Molecular Life Sciences, University of Zürich, Zürich, Switzerland
| | | | | | | | - Stephen F. Goodwin
- Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, United Kingdom
| | - Daniel Bopp
- Institute of Molecular Life Sciences, University of Zürich, Zürich, Switzerland
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