Alexander S. Raikhel
University of California, Riverside
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Primary Section: 61, Animal, Nutritional, and Applied Microbial Sciences Secondary Section: 44, Microbial Biology Membership Type:
Member
(elected 2009)
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Research Interests
My research has elucidated the cellular, molecular and genetic mechanisms underlying the process of insect egg production. Because their egg development is tightly linked to the intake of vertebrate blood, blood-feeding insects, such as mosquitoes, serve as vectors of numerous diseases devastating to humans and domestic animals. My early cell biological investigations have lead to a basic understanding of developmental programs occurring in mosquito females under the control of blood meal-driven regulatory cascades. This was followed by the biochemical and molecular characterization of a system of ligands and receptors involved in these processes. Control by the steroid hormone, 20-hydroxyecdysone, is central to the regulation of mosquito egg development, and we have deciphered the genetic hierarchy of transcriptional regulators underlying this hormone action. The cyclicity of egg maturation in mosquitoes necessitates their frequent contacts with vertebrate hosts, thereby aiding the transmission of pathogens. We determined the molecular basis of genetic switches required for a transition from one egg maturation cycle to the next. Importantly, we found that nutritional control overrides other regulatory mechanisms and amino acids from the ingested blood signal directly via the target-of-rapamycin kinase pathway to activate massive translational and transcriptional events leading to egg maturation. Development of genetic transformation in mosquitoes permitted us to perfect this technique as a tool to study regulatory regions of blood meal-regulated genes. This, in turn, has lead to the development of transgenic mosquitoes with altered immunity and has launched studies of mosquito immunity and its interaction with pathogens.
