This proposal focuses on the molecular basis for diapause (dormancy) in the northern house mosquito, Culex pipiens. In the early autumn adult females of this species seek protected sites and remain there throughout the winter months in a reproductively inactive state know as diapause. Although many aspects of the physiology and environmental control of diapause are well known, there is little information concerning the molecular basis for this diapause or the diapause of any other vector species. Obtaining such information is critical not only for understanding regulation of seasonal cycles of mosquitoes, but also for understanding the seasonality of pathogens the mosquito transmit. In the case of Cx. pipiens the overwintering females appear to harbor West Nile virus, and thus serve as the mechanism for reintroducing the virus into bird populations the following spring. Our initial studies using suppressive subtractive hybridization (SSH) have identified four categories of genes that are upregulated in early diapause. These include genes involved in the diapause-associated switch from blood feeding to sugar feeding, the arrest of development, cold-hardening, and responding to juvenile hormone. Similar SSH experiments will examine mid and late stages of diapause. Clones isolated with this technique will be further characterized by full-length sequencing, by evaluating expression patterns throughout diapause using northern blotting and real-time PCR, by examining tissue-specific expression patterns, and by evaluating gene function using RNA interference. We also plan to use SSH to search for genes associated with the programming phase of diapause (early pupal stage). Such genes are likely to be involved in the decision to either enter or avert diapause. At the conclusion of this study we expect to have identified major gene pathways involved in the regulation of diapause in Cx. pipiens, thus allowing us to begin the construction of a regulatory hierarchy for diapause in this species. We anticipate that these results will suggest vulnerable targets for disrupting diapause and may provide clues for how viral replication is halted during the winter months.

Agency
National Institute of Health (NIH)
Institute
National Institute of Allergy and Infectious Diseases (NIAID)
Type
Research Project (R01)
Project #
5R01AI058279-05
Application #
7585282
Study Section
Special Emphasis Panel (ZRG1-VB (01))
Program Officer
Costero, Adriana
Project Start
2005-07-01
Project End
2011-03-31
Budget Start
2009-04-01
Budget End
2011-03-31
Support Year
5
Fiscal Year
2009
Total Cost
$208,590
Indirect Cost
Name
Ohio State University
Department
Zoology
Type
Schools of Arts and Sciences
DUNS #
832127323
City
Columbus
State
OH
Country
United States
Zip Code
43210
Sim, Cheolho; Denlinger, David L (2013) Juvenile hormone III suppresses forkhead of transcription factor in the fat body and reduces fat accumulation in the diapausing mosquito, Culex pipiens. Insect Mol Biol 22:1-11
Lopez-Martinez, Giancarlo; Meuti, Megan; Denlinger, David L (2012) Rehydration driven RNAi: a novel approach for effectively delivering dsRNA to mosquito larvae. J Med Entomol 49:215-8
Zhang, Qirui; Denlinger, David L (2011) Elevated couch potato transcripts associated with adult diapause in the mosquito Culex pipiens. J Insect Physiol 57:620-7
Benoit, Joshua B; Lopez-Martinez, Giancarlo; Patrick, Kevin R et al. (2011) Drinking a hot blood meal elicits a protective heat shock response in mosquitoes. Proc Natl Acad Sci U S A 108:8026-9
Sim, Cheolho; Denlinger, David L (2011) Catalase and superoxide dismutase-2 enhance survival and protect ovaries during overwintering diapause in the mosquito Culex pipiens. J Insect Physiol 57:628-34
Zhang, Q; Denlinger, D L (2011) Molecular structure of the prothoracicotropic hormone gene in the northern house mosquito, Culex pipiens, and its expression analysis in association with diapause and blood feeding. Insect Mol Biol 20:201-13
Benoit, Joshua B; Lopez-Martinez, Giancarlo; Phillips, Zachary P et al. (2010) Heat shock proteins contribute to mosquito dehydration tolerance. J Insect Physiol 56:151-6
Kim, M; Sim, C; Denlinger, D L (2010) RNA interference directed against ribosomal protein S3a suggests a link between this gene and arrested ovarian development during adult diapause in Culex pipiens. Insect Mol Biol 19:27-33
Benoit, Joshua B; Patrick, Kevin R; Desai, Karina et al. (2010) Repeated bouts of dehydration deplete nutrient reserves and reduce egg production in the mosquito Culex pipiens. J Exp Biol 213:2763-9
Kim, Mijung; Denlinger, David L (2010) A potential role for ribosomal protein S2 in the gene network regulating reproductive diapause in the mosquito Culex pipiens. J Comp Physiol B 180:171-8

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