Examining the roles of microRNAs in Aedes aegypti and Drosophila melanogaster spermatogenesis
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MicroRNAs (miRNAs) are small, non-coding RNAs that act as regulators of gene expression at the post-transcriptional level in plants and animals. In animal cells, miRNAs typically bind with imperfect complementation to sequences within the 3′ UTRs of mRNAs, thereby inhibiting the translation of the transcripts. MiRNAs affect a variety of developmental pathways, and some of them appear to play important roles in defining the differential gene expression within the mammalian testis and during spermatogenesis; their functions in insects, however, remain largely unexplored. In this study, I examined the expression of several putative testis-specific miRNAs in different tissues and developmental stages of the mosquito Aedes aegypti and the vinegar fly Drosophila melanogaster. MiRNAs -9, -34, -100, -124, and -219 were all expressed in the testes of the two insects, but some differences in their expression in other tissues were observed. One particular miRNA, miR-34, was examined more thoroughly, and was confirmed to target genes that either have functions in spermatogenesis or have a testis-specific expression pattern in the two dipteran insects. Inhibition of miR-34, using antisense oligonucleotides, and RNA interference-mediated knockdown of its target, aae/014067, in A. aegypti negatively impacted the fertility of the mosquito males. These results suggest that both aae/014067 and miR-34 are clearly associated with A. aegypti male fertility and the disruption of their normal expression could render mosquitoes sterile, which would help in the development of sterile male release programs, to reduce the risk of mosquito-borne disease without the use of broad-spectrum pesticides that kill many non-target species.