Molecular characterization and expression profiling of and -like homologs in the black tiger shrimp, .

() and () genes have been proven to play a key role in sex determination pathways in many Arthropods, including insects and crustaceans. In this study, a paralog of  ( and 2 isoforms of -like gene ( and ) were identified and characterized The full cDNA sequence of  consisted of 1,774 bp with the longest open reading frame (ORF) of 744 bp encoding for 247 amino acids. The PmOvtra 2 exhibited a predicted RNA-recognition motif (RRM) domain and two arginine-serine (RS) regions, suggesting its function in RNA splicing. The full cDNA sequence of  consisted of 1,306 bp with 1,182 bp ORF encoding for 393 amino acids, whereas the full cDNA sequence of  consisted of 1,858 bp with 1,437 bp ORF encoding 478 amino acids. The deduced amino acid sequences of Pmfru-1 and Pmfru-2 exhibited highly conserved domains of Fru proteins, including Broad-complex, Tramtrack and Bric-a-brac (BTB), and zinc finger (ZF) domains. In addition, and were suggestively originated from the same single genomic locus by genomic sequence analysis Specifically, pre-mRNA was alternatively spliced for and to include mutually exclusive exon 7 and exon 6, respectively. Temporal and spatial expression of , and were also investigated by qPCR. The results showed that all were expressed in early developmental stages with undifferentiated gonads starting from nauplius until postlarvae The expression of  started at nauplius stage and gradually increased from mysis to postlarvae (PL) 1. However, the expression of  was low at the nauplii stage and slightly increased from protozoea to PL5, whereas the expression of  maintained a low level from nauplius to mysis and then gradually increased at the PL stages. Expressions of  and were detected in various tissues including nervous tissue, gill, heart, hepatopancreas, gut, and gonads. Interestingly, the sexually dimorphic expression of  and was demonstrated in fully developed gonads in which the ovary showed significantly higher expressions than the testis The great difference in the expression pattern of  and in the ovary and testis suggested their roles in the female sex determination in .