Many important mosquito vectors of transmissible disease that live in temperate zones enter an overwintering dormancy (diapause). Though this period of dormancy results in a significant decrease or absence of the disease during this portion of the year, the overwintering stage of the mosquito can harbor the pathological agents during this time and thus reinitiate disease transmission the following spring. This appears to be a possible scenario explaining the reappearance of West Nile virus in the New York City area following the initial outbreak in the summer of 1999. In this case, diapausing adult females of Culex pipiens were found to harbor the virus during the winter months and such mosquitoes may have contributed to reintroducing the disease into bird populations the following season. Thus, this stage is critical for understanding the seasonal occurrence of vector-borne diseases, and understanding the physiological and molecular basis for diapause could provide significant clues for understanding how the pathogen is regulated. Suppressive subtractive hybridization was used to identify specific genes upregulated and downregulated during Cx. pipiens diapause. A number of genes have been isolated including those putatively involved in metabolism (fatty acid synthase and malate dehydrogenase), an arrest in ovarian development (ribosomal proteins S3A and S6), and cytoskeletal structure (b-tubulin and actin). We anticipate that these results will provide a basis for understanding the molecular regulation of this diapause and may prove useful in identifying vulnerable targets for disrupting the mosquito during this stage.
Species 1: Diptera Culicidae Culex pipiens (northern house mosquito)
Keywords: diapause
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