Identification and Characterization of the Sex-Determiner <b><i>Transformer-2</i></b> Homologue in Chinese Shrimp, <b><i>Fenneropenaeus chinensis</i></b>

Abstract

The transformer-2 gene, encoding a protein (Tra-2) which directs sex-specifically alternative splicing of doublesex (dsx) pre-mRNA in combination with the transformer (Tra) protein, has been proved to play important roles on sex differentiation and sex development in Drosophila melanogaster. In the present study, a tra-2 homologue (FcTra-2) was cloned and characterized in the Chinese shrimp, Fenneropenaeus chinensis. A FcTra-2 genomic DNA sequence with a length of 8,871 bp was obtained and verified to consist of 7 exons and 6 introns. Three alternatively spliced mRNA transcripts, designated as FcTra-2a, FcTra-2b and FcTra-2c, were isolated and characterized. Sequence analysis showed that FcTra-2 included a RNA recognition motif and a linker region, which shared high sequence identities with Tra-2 from other species and 2 arginine/serine rich regions. Further studies were performed on the isoform FcTra-2c, since it exhibited a significantly higher expression level in ovary than in other tissues. In early developmental stages of the shrimp, FcTra-2c was detected to suddenly increase its expression level at the mysis stage. In juvenile stage, FcTra-2c displayed a significantly higher expression level in female Chinese shrimp than in males. These data indicated that FcTra-2 might be involved in female sex determination in Chinese shrimp.

Comparative Transcriptome Analysis Reveals Sex-Biased Gene Expression in Juvenile Chinese Mitten Crab Eriocheir sinensis

“…Together with the previously cloned sex-lethal (S xl ) [ 41 ] and our identified double sex ( dsx ) [ 44 ], most of ortholog genes in ‘Sxl-Tra/Tra-2-Dsx/Fru’ pathway are detected in the mitten crab. As suggested in the penaeid shrimp [ 16 , 45 ], the present data provides a hint that the mitten crab might adopt a similar sex determination pathway with that in Drosophila . However, the absence of Tra and lack of a sex specificity of Sxl in the mitten crab, also reported in the silkworm Bombyx mori [ 46 – 48 ], imply that genetic regulation for sex determination potentially does not initiate from Sxl .…”

Gonadal transcriptomic analysis and differentially expressed genes in the testis and ovary of the Pacific white shrimp (Litopenaeus vannamei)

“…The first step toward understanding molecular mechanisms of reproduction is to identify and characterize sex-related genes and regulatory pathways. Many efforts have been made to reveal sex-related genes, and many of these genes are cloned and characterized in shrimp; for example, M-phase phosphoprotein 6 ( MPP6 ) [ 10 ], cell division cycle 2 ( Cdc2 ) [ 11 ], cyclin A and cyclin B [ 12 ], gonad-inhibiting hormone ( GIH ) [ 13 ], mitogen-activating protein kinase 1 ( MAPK1 ) [ 14 ], prostaglandin reductase 1 [ 15 ], and valosin-containing protein ( VCP ) [ 16 ] in Penaeus monodon ; and sex-determiner transformer-2 ( Tra-2 ) [ 17 ], activated protein kinase C1 ( RACK1 ) [ 18 ], and cell apoptosis susceptibility ( FcCAS ) [ 19 ] in Chinese shrimp Fenneropenaeus chinensis . In L. vannamei , vasa-like , vitellin , gonadotropin-releasing hormone-like and a sex-related marker have been identified [ 20 – 23 ].…”

Applying the Power of Transcriptomics: Understanding Male Sexual Development in Decapod Crustacea

“…Following this, there is no knowledge of the master sex-regulator that triggers the onset of sex determination. A range of sex determination linked orthologues have been identified in the decapods, mainly guided by genes characterised in the arthropods: these include orthologues of the master sex-determinant in Drosophila, Sxl(Zhang et al 2013a;Shen et al, 2014;Powell et al 2015; Chandler et al in press) and downstream mediators TRA and TRA-2(Leelatanawit et al 2009;Li et al 2012b;Zhang et al 2013b;Cui et al 2015;Liu et al 2015; in press) as well as genes from C. elegans such as FEM-1(Ma et al 2012;Jin et al 2013; Goa et al 2014;Robinson et al 2014;Cui et al 2015;Liu et al 2015;Powell et al 2015;Song et al 2015). However, due to the rapid and repetitive divergence of sex determination systems(Stothard and Pilgrim 2003;Suzuki 2010;Kopp 2012;Matson and Zarkower 2012) the functional significance of these genes in decapods is questionable.…”