The sex determination in <i>Ellobius lutescens</i> remains bizarre

Abstract

Mammalian sex determination and gonad differentiation are the result of a complex interaction of fine-tuned spatial and temporal gene expression with threshold levels of individual genes. The male pathway is initiated by SRY. Some exceptional mammals determine male sex without the SRY gene and even without a Y chromosome. Ellobius lutescens in this report is one example of this “weird” species. We provide key data on the genomic level that there are no coarse differences in the genomes of male and female animals by comparative genomic hybridization. On the gene level we studied the gene Nr5a1 for the orphan nuclear receptor, steroidogenic factor SF-1, a central constituent for gonad differentiation and adrenal gland development. The Ellobius lutescens Nr5a1 gene was mapped to the proximal short arm of chromosome 2 by fluorescence in situ hybridization. In addition, we provide evidence by linkage analysis in two E. lutescens pedigrees that Nr5a1 is not the key male sex-determining gene in Ellobius lutescens.

Reproduction, postnatal development, and social behavior of Ellobius lutescens Thomas, 1897 (Mammalia: Rodentia) in captivity

“…Contrary to the results of Lederberg (1999), Just et al (2002), Stefan and Steimer (1978), Evdokimov (2013), and Smorkatcheva and Kumaitova (2014) on E. talpinus and E. tancrei, the reproduction potential of E. lutescens was sufficient and the intervals were unsteady. The annual reproductive activity period of E. lutescens was longer than the findings of Coşkun and Ulutürk (2003), Nowak (1995), Evdokimov (2002Evdokimov ( , 2013, and Smorkatcheva and Kumaitova (2014) on E. talpinus and E. tancrei.…”

Two unlinked loci controlling the sex of blue tilapia (Oreochromis aureus)

“…Sry, the gene that initiates the male differentiation cascade in mammals, does not control the sex of monotremes, and so must have taken on a role in sex determination within the last 170 MY (Graves, 2002). A few species of mole have recently lost Sry, and accomplish sex determination by a still unknown mechanism (Just et al, 2002). Birds have a female heterogametic (WZ) system which arose from a different pair of autosomes than the XY chromosomes of mammals some 350 MY ago (Nanda et al, 1999).…”

<i>Ellobius lutescens</i>: Sex Determination and Sex Chromosome

“…We mapped the gene to E. lutescens chromosome no. 2, and found no co-segregation of intragenic marker alleles with sex by an EMD study [Just et al, 2002].…”