| Popis: |
One of the primary avian vectors of West Nile virus in the northern United States, Culex pipiens (L.), enters an adult diapause in late summer and early fall in response to short daylength and low temperature. The mosquitoes first appear in overwintering sites such as caves, culverts, and unheated basements as early as August and remain there until spring when environmental conditions again become favorable for development. Only females enter diapause and most are inseminated prior to entering the hibernation site. In preparation for diapause, females increase their lipid reserves by feeding on sugar-rich sources such as nectar and rotting fruit. Although females programmed for diapause can be enticed to take a blood meal by being placed in close proximity to a host, it appears this rarely, if ever, happens in the field. Failure of diapausing females to take a blood meal is presumably the reason that so few of the overwintering females harbor West Nile virus. Many aspects of diapause in Cx. pipiens have been well documented. There is a good database that describes the physiological features of this diapause, its environmental regulators, and the hormonal control mechanism. What is currently lacking is an understanding of its molecular underpinning. In this study, suppressive subtractive hybridization (SSH) is used to identify genes that are differentially expressed during the adult diapause of Cx. pipiens. Expression patterns are confirmed by northern blot hybridization, and the regulated genes that have been identified are discussed in the context of their possible functional contributions to diapause. |
