Steroidogenic acute regulatory protein (StAR) gene expression construct: Development, nanodelivery and effect on reproduction in air-breathing catfish, Clarias batrachus.

Steroidogenic acute regulatory protein (StAR) is responsible for the relocation of cholesterol across mitochondrial membrane in vertebrates and is, therefore, a key factor in regulating the rate and timing of steroidogenesis. In the present study, we developed chitosan nanoparticle (CNP) conjugated StAR gene construct (CNP-pcDNA4-StAR) in a eukaryotic expression vector, pcDNA4/HisMax A. CNPs of 135.4nm diameter, 26.7mV zeta potential and 0.381 polydispersity index were used for conjugation. The loading efficiency (LE) of pcDNA4-StAR construct with CNPs was found to be 86%. After the 24h of intramuscular injection, the CNP-pcDNA4-StAR plasmid could be detected from testis, brain, kidney and muscle tissues of Clarias batrachus. The transcript levels of important reproductive genes viz. cyp11a1, cyp17a1, 3ß-hsd, 17ß-hsd and cyp19a1 in CNP-pcDNA4-StAR treated group were initially low up to 24h, but significantly increased subsequently up to 120h. In naked pcDNA4-StAR treated group, the mRNA level of 3ß-hsd, 17ß-hsd and cyp19a1 increased initially up to 24h, while cyp11a1 and cyp17a1 increased up to 48h and then started declining. Similar results were obtained for 11-Ketotestosterone and 17ß-estradiol. The results indicate relatively long lasting effects of nano-conjugated construct compared to the construct alone. Furthermore, the histopathology of gonads and liver authenticates its possible role in the gonadal development in fish without any adverse effect.

In silico analysis and expression studies of kisspeptin gene in C. catla.

We report the characterization of kisspeptin gene which is considered to be essential for successful animal reproduction. The full-length cDNA sequence of kiss2 was 583 bp, consisted of 11 bp 5'-UTR (untranslated region) and 194 bp 3'-UTR, respectively. Open reading frame of 378 bp encoding a putative protein of 125 amino acids. The Catla catla kiss2 protein was having a molecular weight of 14.51 kDa and isoelectric point (pI) of 8.46. There were four serine (Ser), four threonine (Thr) and two tyrosine (Tyr) phosphorylation sites and no N-glycosylation sites on the predicted protein. The amino acids on positions 8, 11, 24, 80 and 114 were detected to be ligand binding sites. The signal peptide analysis predicted that C. catla kiss2 is a secretory protein. Kiss2 protein is localized in nuclear region (49.7%) and the extracellular region (38.3%) of the cell. Analysis of tissue distribution revealed that, kiss2 transcripts were predominantly expressed in the brain and gonads, with expression levels in female higher than those of male. Ontogenetic analysis of kiss2 demonstrated that expression level was low during early phase of development stages and more expression was observed during mature stage. Overall present results lay a strong basis for understanding the role of kisspeptin in the neuroendocrine system in teleosts.