ABSTRACT
The mechanism of sex determination remains poorly understood in hemimetabolous insects. Here, in the brown planthopper (BPH), Nilaparvata lugens, a hemipteran rice pest, we identified a feminizing switch or a female determiner (Nlfmd) that encodes a serine/arginine-rich protein. Knockdown of Nlfmd in female nymphs resulted in masculinization of both the somatic morphology and doublesex splicing. The female-specific isoform of Nlfmd, Nlfmd-F, is maternally deposited and zygotically transcribed. Depletion of Nlfmd by maternal RNAi or CRISPR-Cas9 resulted in female-specific embryonic lethality. Knockdown of an hnRNP40 family gene named female determiner 2 (Nlfmd2) also conferred masculinization. In vitro experiments showed that an Nlfmd2 isoform, NlFMD2340, bound the RAAGAA repeat motif in the Nldsx pre-mRNA and formed a protein complex with NlFMD-F to modulate Nldsx splicing, suggesting that NlFMD2 may function as an RNA binding partner of the feminizing switch NlFMD. Our results provide novel insights into the diverse mechanisms of insect sex determination.
ABSTRACT
OBJECTIVE: To verify the miRNA in Aedes albopictus and characterize the expression profile of several miRNAs across all the life stages of Aedes albopictus. METHODS: Based on the published miRNA sequences of Anopheles gambiae and Aedes aegypti, 6 DIG-labeled antisense probes were synthesized. The total RNAs from Aedes albopictus in 6 developmental stages (embryo, early larvae, late larvae, pupa, male and female adults) were extracted with a mirVana miRNA isolation kit, loaded onto 15% denaturing polyacrylamide gel and hybridized with the appropriate DIG-labeled probes. RESULTS: Northern blotting detected 5 miRNAs in Aedes albopictus, of which mir-9a was mainly expressed in embryo and larva stages, let-7 in pupa and adult stages, miR-184 in all life stages, mir-M1 only in the embryos and miR-1175 in all the life stages except for embryos. The expression profiles of these miRNAs in Aedes albopictus were similar to those in D. melanogaster and An.stepheni. miR-1174 was not detected in any of the developmental stages of Aedes albopictus. CONCLUSION: These results present the first direct experimental evidence of miRNA in Aedes albopictus. The expression profiles of the analyzed miRNAs in Aedes albopictus showed stage specificity and conservation with other mosquitoes. Further studies on the functions of these miRNAs may offer new insights in mosquito biology and may lead to novel approaches to the development of insecticides.
