Structural modeling and gene expression analysis of phosvitinless vitellogenin (vgc) in the Indian freshwater murrel, Channa punctatus (Bloch, 1793).

• vgc mRNA of murrel codes for 1272 amino acids (aa) and the predicted molecular weight of VgC protein is 141 kDa • The secondary structure of complete protein sequence of VgC showed the presence of α helix (47.48 %), β turns (3.3 %), random coils (35.85 %). • Protein interactions and phylogenetic analysis confirm its relationship with other non-phosphorylated Zona pellucida or Choriogenin proteins. • Expression of vgc gene at low levels of E 2 suggests that non-phosphorylated Vg protein (VgC), is synthesized earlier than phosphorylated Vgs (VgA and VgB) during oogenesis. Vitellogenin (Vg) is a female-specific egg-yolk precursor protein, synthesized in the liver of fish in response to estrogens. In the present study, complete gene of phosvitinless vitellogenin (vgc) was sequenced, its 3D structure was predicted and validated by web-based softwares. The complete nucleotide sequence of vgc was 4126 bp which encodes for 1272 amino acids and showed the presence of three conserved domains viz. LPD_N, DUF1943 and DUF1944. The retrieved amino acid sequence of VgC protein was subjected to in silico analysis for understanding the structural and functional properties of protein. mRNA levels of multiple vg genes have also been quantified during annual reproductive cycle employing qPCR. A correlation has been observed between seasonal changes in gonadosomatic index with estradiol levels and hepatic expression of three types of vg genes (vga, vgb, vgc) during ovarian cycle of murrel. During preparatory phase, when photoperiod and temperature are low; low titre of E 2 in blood induces expression of vgc gene. A rapid increase in the levels of E 2 favours induction of vgb and vga genes in liver of murrel during early pre-spawning phase when photoperiod is long and temperature is high in nature. These results suggest that among three vitellogenin proteins, VgC is synthesized earlier than VgA and VgB during oogenesis. [ABSTRACT FROM AUTHOR]