The ubiquity and ancestry of insect doublesex

Abstract

The doublesex (dsx) gene functions as a molecular switch at the base of the insect sex determination cascade, and triggers male or female somatic sexual differentiation in Drosophila. Having been reported from only seven current insect orders, the exact phylogenetic distribution of dsx within the largest Arthropod sub-phylum, the Hexapoda, is unknown. To understand the evolution of this integral gene relative to other arthropods, we tested for the presence of dsx within public EST and genome sequencing projects representative of all 32 hexapod orders. We find the dsx gene to be ubiquitous, with putative orthologs recovered from 30 orders. Additionally, we recovered both alternatively spliced and putative paralogous dsx transcripts from several orders of hexapods, including basal lineages, indicating the likely presence of these characteristics in the hexapod common ancestor. Of note, other arthropods such as chelicerates and crustaceans express two dsx genes, both of which are shown to lack alternative splicing. Furthermore, we discovered a large degree of length heterogeneity in the common region of dsx coding sequences within and among orders, possibly resulting from lineage-specific selective pressures inherent to each taxon. Our work serves as a valuable resource for understanding the evolution of sex determination in insects.

Identification and functional characterization of the sex-determining gene doublesex in the sawfly, Athalia rosae (Hymenoptera: Tenthredinidae)

“…Ardsx F1 , Ardsx F2 , and Ardsx F3 also encode the protein with an identical sequence of 337 amino acids (ArDSX F ). ArDSX M and ArDSX F share an N-terminal region of 222 amino acids that encodes a conserved DNA-binding domain called DM domain (or OD1 domain) and part of a conserved dimeriztion domain known as OD2 domain, which is specifically conserved among DSX proteins (Price et al 2015) (Fig. 4a).…”

Disruption of sex‐specific doublesex exons results in male‐ and female‐specific defects in the black cutworm, Agrotis ipsilon

“…A unique feature of insect dsx is the production of sex‐specific isoforms by alternative splicing . In lepidopteran insects, B. mori , H. armigera and O. furnacalis , one male‐specific and multiple female‐specific isoforms were identified .…”

“…A unique feature of insect dsx is the production of sex-specific isoforms by alternative splicing. 18 In lepidopteran insects, B. mori, H. armigera and O. furnacalis, one male-specific and multiple female-specific isoforms were identified. 5 We analyzed genome and cDNA sequences, and identified one male-specific and six female-specific dsx isoforms; we named them Aidsx-m, Aidsx-f1, wileyonlinelibrary.com/journal/ps Aidsx-f2, Aidsx-f3, Aidsx-f4, Aidsx-f5 and Aidsx-f6 ( Fig.…”

“…4, 14,15 Female-and male-specific DSX proteins share a common N-terminal region containing a DNA-binding domain that is essential for transcription factor activity. 16 However, they differ at the C-terminal end, containing a sex-specific oligomerization domain 17,18 that is responsible for exerting effects on DSX-target genes involved in various aspects of sex differentiation. 3,17,19 Although a large number of dsx genes have been identified in non-model insect species, their function is not well studied.…”

Genome sequence of Phormia regina Meigen (Diptera: Calliphoridae): implications for medical, veterinary and forensic research

“…The gene doublesex ( dsx ) is another transcription factor that controls the activity of genes involved in sexual differentiation [66, 80]. Doublesex is differentially spliced, encoding male and female sex specific dsx proteins [66].…”