A novel Dmrt gene is specifically expressed in the testis of Chinese mitten crab, Eriocheir sinensis

Abstract

Dmrt is a family of genes related to the sexual regulators Doublesex of Drosophila melanogaster and Mab-3 of Caenorhabditis elegans. Dmrt genes are widely conserved and known for their involvement in sex determination and differentiation across phyla. In this study, we report here the identification of a novel Dmrt gene, named EsDmrt-like, from Chinese mitten crab Eriocheir sinensis. EsDmrt-like encodes a protein of 236 amino acids without intron. The protein contains a conserved DNA-binding DM domain that is characteristic of Dmrt genes. The DM domain shares 98% identity with that of Drosophila Dmrt99B and vertebrate Dmrt5, but outside the DM domain, there is little homology in sequence and no other conserved domain such as DMA specific to the Dmrt99B and Dmrt3-5. Interestingly, the expression pattern of EsDmrt-like is quite similar with that of vertebrate Dmrt1. Reverse transcription-polymerase chain reaction showed that EsDmrt-like transcripts were detectable only in testis with much higher expression at immature stage. In situ hybridization to gonad sections indicated that the EsDmrt-like mRNA was exclusively localized in Sertoli cells around the periphery of seminiferous tubules and developing germ cells including spermatogonium, spermatocyte, and spermatid, but absent in spermatozoa. This finding strongly suggests an essential role for EsDmrt-like in the male testicular development/differentiation of the crab.

High-density linkage mapping aided by transcriptomics documents ZW sex determination system in the Chinese mitten crab Eriocheir sinensis

“…In contrast to a previous report on a Dmrt-like gene in E. sinensis (Zhang and Qiu, 2010), four Dmrt genes are newly found (Dmrt1, Dmrt2, DmrtA2 and Dmrt11E). Dmrt1, corresponding to marker h1284 on LG3 (Figure 5b), is an important downstream sex determination gene conserved in animals with diverse sex-determining mechanisms, including nematode, fruit fly, fish, amphibians, reptiles, Figure 4 Primary sex determination pathway-related genes detected in E. sinensis transcriptomes.…”

“…However, a recent study of E. sinensis and E. japonicus questioned the reliability of karyotype analysis for inferring sex determination, as the centromeres could not be identified in some of the chromosomes (Lee et al, 2004). Several genes related to sex determination and differentiation were obtained previously (Zhang and Qiu, 2010;Ma et al, 2012;Wang et al, 2012aWang et al, , b, 2013Shen et al, 2014), but no conclusion can be reached on the genetic mechanism of sex determination in crabs.…”

Male Sexual Development and the Androgenic Gland: Novel Insights through the de novo Assembled Transcriptome of the Eastern Spiny Lobster,<b><i> Sagmariasus verreauxi</i></b>

“…It may be that the DMA orthologue in S. verreauxi is a similar truncated DMA-only-containing sequence, or most likely is the result of incomplete sequence coverage. Demonstrating the point that the DMA-domain has minimal phylogenetic signal, neither of the 99B-orthologues identified in M. rosenbergii or the Dmrt identified in E. sinensis (also a 99B orthologue) [Zhang and Qiu, 2010] contained a DMA domain.…”

“…The ancient emergence and conserved function of the Dmrts is evident in their characterization amongst the non-bilaterian animals (such as corals and placozoa), suggesting that they emerged before the divergence of the Eumetazoans [Picard et al, 2015]. Even though the Dmrts have been broadly described [Wexler et al, 2014;Picard et al, 2015], their documentation amongst the Decapods is still limited [Zhang and Qiu, 2010;Ma et al, 2012;Yu et al, 2014].…”

The roles of Dmrt (Double sex/Male-abnormal-3 Related Transcription factor) genes in sex determination and differentiation mechanisms: Ubiquity and diversity across the animal kingdom

“…This mitten crab is a gonochoric animal, but the genetic bases of its sex determination remains unknown. Only one Dmrt gene has been isolated in this species [42]: the EsDMRT-like gene, which shows 37% homology with DMRT99B isolated from Drosophila. This gene is present in both males and females, but is only expressed in the testis (not in ovary, heart, hepatopancreas, muscle, thoracic ganglion or gill) [42].…”