The Sex-Specific Splicing of Doublesex in Brine Shrimp Artemia franciscana

The understanding of sex determination and differentiation in animals has recently made remarkable strides through the use of advanced research tools. At the gene level, the Mab-3-related transcription factor (Dmrt) gene family, which encodes for the typical DNA-binding doublesex/Mab-3 (DM) domain in their protein, is known for its contribution to sex determination and differentiation in insects. In this study, DNA-binding DM domain screening has identified eight transcripts from Artemia franciscana transcriptomic that encode proteins containing one conserved DNA-binding DM domain. The genome mapping confirmed that these eight transcripts are transcribed from six different loci on the A. franciscana genome assembly. One of those loci, the Af.dsx-4 locus, is closely related to Doublesex, a gene belonging to the Dmrt gene family. This locus could be transcribed into three alternative transcripts, namely Af.dsx(4), Af.dsx(F) and Af.dsx(M). While Af.dsx(4) and Af.dsx(F) could putatively be translated to form an identical Af.dsx(F) protein of 186 aa long, Af.dsx(M) translates for an Af.dsx(M) protein of 289 aa long but shares a DNA-binding DM domain. Interestingly, Af.dsx(F) and Af.dsx(M) are confirmed as sex-specific transcripts, Af.dsx(F) is only present in females, and Af.dsx(M) is only present in male individuals. The results suggest that the sex-specific splicing mechanism of the doublesex described in insects is also present in A. franciscana. Af.dxs-4 locus can be used in further studies to clarify the sex determination pathways in A. fracnciscana.