The Nix locus on the male-specific homologue of chromosome 1 in Aedes albopictus is a strong candidate for a male-determining factor

Abstract

BackgroundGlobal concern over the rapid expansion of the Asian tiger mosquito, Aedes albopictus, and its vector competence has highlighted an urgent need to improve currently available population control methods, like the Sterile Insect Technique. Knowledge of the sex determination cascade is a prerequisite for the development of early-stage sexing systems. To this end, we have characterised the putative sex determination gene, Nix, in this species. In Aedes species the chromosome complement consists of three pairs of chromosomes. The sex determination alleles are linked to the smallest homomorphic chromosome.ResultsWe identified the male-specific chromosome 1 of Ae. albopictus that carries the putative male-determining gene Nix. We have also characterised the complete genomic sequence of the Nix gene which is composed of two exons and a short intron. The gene displays different levels of intron retention during development. Comparison of DNA sequences covering most of the Nix gene from individuals across the species range revealed no polymorphism.ConclusionsOur characterisation of the Nix gene in Ae. albopictus represents an initial step in the analysis of the sex determination cascade in this species. We found evidence of intron retention (IR) in Nix. IR might play a role in regulating the expression of Nix during development. Our results provide the basis for the development of new genetic control strategies.Electronic supplementary materialThe online version of this article (10.1186/s13071-018-3215-8) contains supplementary material, which is available to authorized users.

Improved reference genome of the arboviral vector Aedes albopictus

“…A part of the nix gene was previously identified in Ae. albopictus [ 49 , 51 ], and its full-length sequence was described in the assembly of the Ae. albopictus C6/36 cell line [ 52 ].…”

A conserved female-specific larval requirement for MtnB function facilitates sex separation in multiple species of disease vector mosquitoes

“…Although a sex-differentiated region of suppressed recombination extends ~ 100 Mb beyond the M/m locus [ 21 , 49 , 50 ], heteromorphic X and Y chromosomes have not yet evolved in A. aegypti. Likewise, A. albopictus also possesses homomorphic sex chromosomes, and the A. albopictus Nix gene was identified as a strong candidate for a male-determining factor in this species [ 17 , 51 , 52 ]. In contrast, A. gambiae has already evolved separate X and Y chromosomes, with the Yob gene functioning as a male-determining factor on the Y chromosome [ 53 ].…”

Improved reference genome of the arboviral vectorAedes albopictus

“…A part of the nix gene was previously identified in Ae. albopictus (43,46) and its full-length sequence was described in the assembly of the Ae. albopictus C6/36 cell line (10).…”