Transgenic technologies to induce sterility

Abstract

The last few years have witnessed a considerable expansion in the number of tools available to perform molecular and genetic studies on the genome of Anopheles mosquitoes, the vectors of human malaria. As a consequence, knowledge of aspects of the biology of mosquitoes, such as immunity, reproduction and behaviour, that are relevant to their ability to transmit disease is rapidly increasing, and could be translated into concrete benefits for malaria control strategies. Amongst the most important scientific advances, the development of transgenic technologies for Anopheles mosquitoes provides a crucial opportunity to improve current vector control measures or design novel ones. In particular, the use of genetic modification of the mosquito genome could provide for a more effective deployment of the sterile insect technique (SIT) against vector populations in the field. Currently, SIT relies on the release of radiation sterilized males, which compete with wild males for mating with wild females. The induction of sterility in males through the genetic manipulation of the mosquito genome, already achieved in a number of other insect species, could eliminate the need for radiation and increase the efficiency of SIT-based strategies. This paper provides an overview of the mechanisms already in use for inducing sterility by transgenesis in Drosophila and other insects, and speculates on possible ways to apply similar approaches to Anopheles mosquitoes.

Figure 1

The internal reproductive organs of a male Anopheles gambiae transgenic mosquito. The male accessory glands (M), in which seminal secretions containing proteins and peptides are produced, and the testes (T), where sperm cells develop, are indicated. The image is an overlay of a fluorescent and a transmission microphotograph. The fluorescence in the testes is derived from the expression of a green fluorescent protein egfp reporter gene driven by the testis-specific β2-tubulin promoter [37]. The scale bar is indicated.