Characterization of DMRT1 variants for testis determination and differentiation in emu.

Introduction: DMRT1 on the Z chromosome is a conserved male sex-determining gene in birds. In chickens, a representative model species of Neognathae, the function of DMRT1 has been well characterized. In contrast, Palaeognathae species such as the emu possess less differentiated sex chromosomes and thus provide a valuable system for investigating avian sex determination, yet molecular studies remain limited.

Identification of candidate transcription factors that regulate Sox9 expression through the testis-specific enhancer in the Amami spiny rat Tokudaia osimensis, an XO/XO mammal.

Testicular differentiation of undifferentiated gonads is triggered by the SRY/Sry (sex-determining region of chromosome Y) gene on the Y chromosome in most mammals. SRY and NR5A1 (nuclear receptor subfamily 5, group A, member 1) proteins regulate transcription of the autosomal SOX9/Sox9 (SRY-box9) gene in XY embryonic gonads, inducing testicular differentiation. One exception, the Amami spiny rat (Tokudaia osimensis), lacks the Y chromosome and Sry.

Identification of a New Enhancer That Promotes Sox9 Expression by a Comparative Analysis of Mouse and Sry-Deficient Amami Spiny Rat.

Introduction: Testis differentiation is initiated by the SRY gene on the Y chromosome in mammalian species. However, the Amami spiny rat, Tokudaia osimensis, lacks both the Y chromosome and the Sry gene and acquired a unique Sox9 regulatory mechanism via a male-specific duplication upstream of Sox9, without Sry. In general mammalian species, the SRY protein binds to a testis-specific enhancer to promote SOX9 gene expression.