A synthetic male-specific sterilization system using the mammalian pro-apoptotic factor in a malaria vector mosquito

Abstract

Conditional cell death systems are useful for various aspects of basic science with a wide range of applications, including genetic pest control. We recently demonstrated that expression of the mammalian pro-apoptotic factor, B-cell leukaemia/lymphoma 2-associated X protein (Bax), can induce apoptosis in specific tissues by using tissue specific promoters in silkworm and mosquito. Here, we newly identified a functional promoter in the Asian malaria vector, Anopheles stephensi , which enables gene expression specifically in the testis. We produced a transgenic mosquito line that expresses mouse Bax under the control of this testis-specific promoter. Transgenic mosquito males exhibited aberrant testes without functional sperm and complete sterility, whereas transgenic females maintained normal fecundity. Despite their abnormal testes, the transgenic males maintained normal function of male accessory glands and typical mating behaviour. As a result of mating with these males, females showed refractoriness to further mating. These results suggest that transgenic males induce female sterility via mating. The mosquito is one of the most important disease vectors, and the control of their population benefits global public health. Thus, this Bax-mediated synthetic male-specific sterilization system could be applied to population control of mosquitoes.

High-resolution in situ analysis of Cas9 germline transcript distributions in gene-drive Anopheles mosquitoes

“…We examined endogenous transcript accumulation profiles for each of these genes in both male and female reproductive tissues of A. stephensi to evaluate whether their promoters might be of potential future interest for driving germline-restricted expression of Cas9. We used the previously described A. stephensi male-specific β 2 -tubulin gene ( Yamamoto et al 2019 ), expressed in meiotic cells of the testes, as a control of late meiotic expression and technique ( Figure 4 ). We first confirmed that β 2 -tubulin transcription is indeed male-specific using quantitative gene amplification (qPCR; Supplementary Figure S3 ).…”

Laboratory testing of low concentration (<1 ppm) of copper to prolong mosquito pupation and adult emergence time: An alternative method to delay mosquito life cycle

“…Anopheles stephensi SDA500 strain, was maintained in 26˚C, 60-80% relative humidity, and a 13-h/11-h light/dark cycle at Jichi Medical University [13]. Adults were fed on a filter paper soaked with 5% fructose (Nacalai Tesques, Kyoto, Japan).…”

CRISPR-mediated germline mutagenesis for genetic sterilization of Anopheles gambiae males

“…Developing sterilization methods that specifically target fertility genes may provide an alternative avenue to produce males that are fit for mating. Multiple, more precise, transgenic sterilization systems have been developed in some mosquito vectors, including those which preserve male fertility but kill offspring in post-embryonic developmental stages 19 – 22 , those which express pro-apoptotic factors in the testes 23 , and those which combine male sterilization and female-killing 24 . While these systems cause transient species-specific population suppression following release, none have yet been adopted in the most important African malaria vector Anopheles gambiae .…”