Molecular cloning, characterization and expression of Lc-Sox11a in large yellow croaker Larimichthys crocea.

Sox genes play important roles in various developmental processes such as sex determination, embryogenesis, oogenesis, neurogenesis, and larval development. In order to clarify the roles of Sox genes in the developmental process of large yellow croaker, the full-length cDNA of the Sox11a gene (Lc-Sox11a) was cloned for the first time. Bioinformatics analysis indicated that Lc-Sox11a contains a protein of 366 amino acids with a Ser-rich region, a C-terminal conserved region, and a high mobility group box. The expression of Lc-Sox11a in different tissues of both sexes and in different developmental embryonic stages revealed that Lc-Sox11a were expressed with tissue and gender specificity, of which the expression level in female was ovary>brain>eye>gill; in male was brain>testis>gill. The gender differences occurred in the brain and eye with the male brain>female brain, female eye>male eye. Moreover, the expression of Lc-Sox11a in the gonad and brain at different growth stages was detected. Significant up-regulated expression of Lc-Sox11a was found in the ovary and the male brain at 1000dph (days post hatching) compared with 270dph and 635dph. However, significant down-regulated expression of Lc-Sox11a occurred in the testis with growth. Besides, the expression of Lc-Sox11a in the female brain showed a trend of first rising then falling, with the highest peak in 635dph. The results of in situ hybridization displayed that Lc-Sox11a was widely distributed only in cytoplasm of oocytes at each stage in oogenesis. In early stage of oocytes, Lc-Sox11a was expressed weakly and evenly. As the appearance of vacuoles and synthesis of yolks, positive signals of Lc-Sox11a distributed intensively in the residual cytoplasm. In spermatogenesis, Lc-Sox11a was distributed in cytoplasm of all male germ cells except spermatozoon with spermatogonium>spermatocyte>spermatid. During embryogenesis, Lc-Sox11a was expressed in most embryonic stages, the highest expression occurred in the formation-of-eye-lens stage, closely followed by the closure-of-blastopore stage, then the beginning-of-heart-pulsation stage. The results of whole mount in situ hybridization showed that the expression of Lc-Sox11a began to increase beginning with the multiple-cell stage, with the major distribution of Lc-Sox11a in the brain and eye areas in the pre-hatching stage.

A second form of Sox11 homologue identified in the orange-spotted grouper Epinephelus coioides: analysis of sequence and mRNA expression patterns.

Sox genes, a family of genes related to the mammalian sex-determining region Y (SRY) gene, are found throughout the animal kingdom, and involved in diverse developmental processes including sex determination and neurogenesis. Previously, we have identified one sox11 homologue, sox11b, from the ovary of the orange-spotted grouper. In the present study, another sox11 homologue, sox11a, was cloned from the brain. The orange-spotted grouper Sox11a contained the signature features of mammalian SOX11 homologues except the Pro-Glu rich region, was clustered with Sox11a homologues of other teleosts in the phylogenetic tree, and shared higher homologies with Sox11 of other species than the duplicated copy Sox11b. Interestingly, significant conservation was observed in the 3'UTR of sox11a but not sox11b transcripts when compared with mammalian Sox11 homologues. The expression of sox11a mRNA was detected in a wide range of tissues, with higher abundances in the central nervous system. During embryogenesis and larval development, the expression of sox11a mRNA remained at considerably high levels at all stages examined, from newly fertilized eggs, through organogenesis, to the larvae 18days posthatching. Together, these results indicated that the orange-spotted grouper sox11a was evolutionarily more conserved than sox11b, and may play important roles in neurogenesis, embryogenesis, and larval development.