Targeting gene expression to the female larval fat body of transgenic Aedes aegypti mosquitoes

Abstract

As the fat body is a critical tissue for mosquito development, metamorphosis, immune and reproductive system function, characterization of regulatory modules targeting gene expression to the female mosquito fat body at distinct life stages is much needed for multiple, varied strategies for controlling vector-borne diseases such as dengue and malaria. The hexameric storage protein, Hexamerin-1.2, of the mosquito, Aedes atropalpus, is female-specific and uniquely expressed in the fat body of fourth-instar larvae and young adults. We have identified in the Hex-1.2 gene, a short regulatory module that directs female-, tissue-, and stage-specific lacZ reporter gene expression using a heterologous promoter in transgenic lines of the dengue vector, Aedes aegypti. Male transgenic larvae and pupae of one line expressed no E. coli β-galactosidase or transgene product; in two other lines reporter gene activity was highly female-biased. All transgenic lines expressed the reporter only in the fat body. However, lacZ mRNA levels were no different in males and females at all stages examined, suggesting that the gene regulatory module drives female-specific expression by post-transcriptional regulation in the heterologous mosquito. This regulatory element from the Hex-1.2 gene thus provides a new molecular tool for transgenic mosquito control as well as functional genetic analysis in aedine mosquitoes.

Identification of germline transcriptional regulatory elements in Aedes aegypti

“…In Aedes aegypti , a number of regulatory elements able to drive gene expression in specific tissues have been identified through transgenesis. These include the midgut 23 24 , the eye 25 , salivary glands 26 27 , testis 28 , fat body 29 30 31 , female flight muscle 32 , and ubiquitous expression 33 34 . Several regulatory elements have also been identified that drive expression in the female germline.…”

Transcriptome Sequencing and Developmental Regulation of Gene Expression in Anopheles aquasalis

“…Hexamerin-encoding transcripts corresponding to contig 1221 were found highly accumulated in both larvae and adults. Hexamerins expressed in adult mosquitoes have been reported [47] but their function during this developmental stage is unknown. Abundant larval mRNAs encoding ribosomal proteins, translation initiation factors and elongation factors represent the active protein synthesis machinery, consistent with the rapid growth rate during the third and fourth instars of mosquito larvae.…”