Sex-determining mechanisms in insects

Abstract

Sex determination refers to the developmental programme that commits the embryo to either the male or the female pathway. The animal kingdom possesses a wealth of mechanisms via which gender is decided, all of which are represented among the insects. This manuscript focuses on a number of insects for which genetic and molecular data regarding sex determination mechanisms are available. The sex determination genetic cascade of Drosophila melanogaster is first discussed, followed by an analysis of the sex determination genes of other dipteran and nondipteran insects. Representative examples of sex determination mechanisms that differ in their primary signal are also described. Finally, some evolutionary aspects of these mechanisms are discussed.

Insect sex determination: it all evolves around transformer

“…some Lepidoptera [46 ]) and paternal X chromosome inactivation (e.g. coccids (Homoptera) and Sciarid flies [1 ]). Whether and how tra regulation occurs in these groups remains an interesting unanswered question.…”

“…Green boxes indicate species from which only dsx has been reported but presence of tra has been inferred from sequence data. Blue box indicates species in which a feminizing gene has been found but no dsx or tra yet (modified after [1 ]). …”

“…Upper part: Insect classification on the left is redrawn from Sanchez [1 ]. On the right is the UPGMA consensus tree of the transformer protein sequences with bootstrap values indicated at the nodes (UPGMA cluster with a Jones-Taylor-Thornton matrix, 1000 bootstraps).…”

“…Although this suggests a common underlying genetic mechanism, an astoundingly diverse array of pathways regulates sex determination. Sanchez [1 ] reviewed current knowledge of sex determining mechanisms with a focus on primary signals. In flies (Diptera) the gene doublesex (dsx) acts as a conserved major switch at the bottom of the sexdetermining cascade [1 ,2,3].…”

Diversification of doublesex function underlies morph-, sex-, and species-specific development of beetle horns

“…Second, previous studies have shown that dsx has a highly conserved function as the terminal gene in the sex determination pathway that regulates the sex-limited expression of downstream genes, leading to sexually dimorphic development and behavior across diverse insects (7)(8)(9). The structure and function of dsx are best understood from studies in Drosophila.…”