Towards a Semen Proteome of the Dengue Vector Mosquito: Protein Identification and Potential Functions

PLoS Neglected Tropical Diseases, Mar 2011

Background No commercially licensed vaccine or treatment is available for dengue fever, a potentially lethal infection that impacts millions of lives annually. New tools that target mosquito control may reduce vector populations and break the cycle of dengue transmission. Male mosquito seminal fluid proteins (Sfps) are one such target since these proteins, in aggregate, modulate the reproduction and feeding patterns of the dengue vector, Aedes aegypti. As an initial step in identifying new targets for dengue vector control, we sought to identify the suite of proteins that comprise the Ae. aegypti ejaculate and determine which are transferred to females during mating. Methodology and Principal Findings Using a stable-isotope labeling method coupled with proteomics to distinguish male- and female-derived proteins, we identified Sfps and sperm proteins transferred from males to females. Sfps were distinguished from sperm proteins by comparing the transferred proteins to sperm-enriched samples derived from testes and seminal vesicles. We identified 93 male-derived Sfps and 52 predicted sperm proteins that are transferred to females during mating. The Sfp protein classes we detected suggest roles in protein activation/inactivation, sperm utilization, and ecdysteroidogenesis. We also discovered that several predicted membrane-bound and intracellular proteins are transferred to females in the seminal fluids, supporting the hypothesis that Ae. aegypti Sfps are released from the accessory gland cells through apocrine secretion, as occurs in mammals. Many of the Ae. aegypti predicted sperm proteins were homologous to Drosophila melanogaster sperm proteins, suggesting conservation of their sperm-related function across Diptera. Conclusion and Significance This is the first study to directly identify Sfps transferred from male Ae. aegypti to females. Our data lay the groundwork for future functional analyses to identify individual seminal proteins that may trigger female post-mating changes (e.g., in feeding patterns and egg production). Therefore, identification of these proteins may lead to new approaches for manipulating the reproductive output and vectorial capacity of Ae. aegypti.

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Towards a Semen Proteome of the Dengue Vector Mosquito: Protein Identification and Potential Functions

et al. (2011) Towards a Semen Proteome of the Dengue Vector Mosquito: Protein Identification and Potential Functions. PLoS Negl Trop Dis 5(3): e989. doi:10.1371/journal.pntd.0000989 Towards a Semen Proteome of the Dengue Vector Mosquito: Protein Identification and Potential Functions Laura K. Sirot 0 Melissa C. Hardstone 0 Michelle E. H. Helinski 0 Jose M. C. Ribeiro 0 Mari Kimura 0 Prasit Deewatthanawong 0 Mariana F. Wolfner 0 Laura C. Harrington 0 Pattamaporn Kittayapong, Mahidol University, Thailand 0 1 Department of Molecular Biology and Genetics, Cornell University , Ithaca , New York, United States of America, 2 Department of Entomology, Cornell University , Ithaca , New York, United States of America, 3 Laboratory of Malaria and Vector Research, National Institute of Allergy and Infectious Disease, National Institutes of Health , Bethesda, Maryland , United States of America Background: No commercially licensed vaccine or treatment is available for dengue fever, a potentially lethal infection that impacts millions of lives annually. New tools that target mosquito control may reduce vector populations and break the cycle of dengue transmission. Male mosquito seminal fluid proteins (Sfps) are one such target since these proteins, in aggregate, modulate the reproduction and feeding patterns of the dengue vector, Aedes aegypti. As an initial step in identifying new targets for dengue vector control, we sought to identify the suite of proteins that comprise the Ae. aegypti ejaculate and determine which are transferred to females during mating. Methodology and Principal Findings: Using a stable-isotope labeling method coupled with proteomics to distinguish male- and female-derived proteins, we identified Sfps and sperm proteins transferred from males to females. Sfps were distinguished from sperm proteins by comparing the transferred proteins to sperm-enriched samples derived from testes and seminal vesicles. We identified 93 male-derived Sfps and 52 predicted sperm proteins that are transferred to females during mating. The Sfp protein classes we detected suggest roles in protein activation/inactivation, sperm utilization, and ecdysteroidogenesis. We also discovered that several predicted membrane-bound and intracellular proteins are transferred to females in the seminal fluids, supporting the hypothesis that Ae. aegypti Sfps are released from the accessory gland cells through apocrine secretion, as occurs in mammals. Many of the Ae. aegypti predicted sperm proteins were homologous to Drosophila melanogaster sperm proteins, suggesting conservation of their sperm-related function across Diptera. Conclusion and Significance: This is the first study to directly identify Sfps transferred from male Ae. aegypti to females. Our data lay the groundwork for future functional analyses to identify individual seminal proteins that may trigger female postmating changes (e.g., in feeding patterns and egg production). Therefore, identification of these proteins may lead to new approaches for manipulating the reproductive output and vectorial capacity of Ae. aegypti. - Funding: This work was funded in part by grant R21AI0176828 from National Institute of Allergy and Infectious Diseases, National Institutes of Health, and by NYC-139437 HATCH project to LCH and MFW. LKS was supported in part by a National Institutes of Health National Research Service Award fellowship F32GM074361. JMCR was supported by the Intramural Research Program of the Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript. Competing Interests: The authors have declared that no competing interests exist. . These authors contributed equally to this work. Male seminal fluid proteins (Sfps) influence female reproductive and feeding behaviors in a range of insects studied to date (reviewed in [1],[2]). Therefore, these proteins may provide targets or pathways that can be manipulated to reduce pathogen transmission by blood-feeding arthropods. The Aedes aegypti mosquito transmits several pathogens of concern to human health, including the viruses that cause dengue and dengue hemorrhagic fever (DHF) ([3]). Dengue, the most important mosquito-borne virus impacting human health, is a re-emerging disease in the tropical regions of the world. There is currently no vaccine against, or cure for, dengue, although research in this area is ongoing ([46]). Therefore, prevention of dengue infection depends heavily on control of its mosquito vector. Understanding mosquito reproductive biology is critical to developing effective vector control methods. Previous research on Ae. aegypti suggests that mating and, specifically, male-derived proteins may play an important role in modulating female reproduction and feeding behavior. Upon mating, female Ae. aegypti undergo a series of (...truncated)


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Laura K. Sirot, Melissa C. Hardstone, Michelle E. H. Helinski, José M. C. Ribeiro, Mari Kimura, Prasit Deewatthanawong, Mariana F. Wolfner, Laura C. Harrington. Towards a Semen Proteome of the Dengue Vector Mosquito: Protein Identification and Potential Functions, PLoS Neglected Tropical Diseases, 2011, Volume 5, Issue 3, DOI: 10.1371/journal.pntd.0000989