Whole mitogenome analysis and phylogeny of freshwater fish red-finned catopra (Pristolepis rubripinnis) endemic to Kerala, India.

The freshwater leaf fish Pristolepis rubripinnis belongs to the family Pristolepididae, restricted to Pamba and Chalakudy rivers of Kerala, India. In the present study, we sequenced the complete mitogenome of P. rubripinnis and analysed its phylogeny in the order Anabantiformes. The 16622-bp long genome comprised of 13 protein-coding genes, two rRNA genes, 22 transfer RNAs (tRNAs) genes and had a noncoding control region. All the protein-coding genes, tRNA and rRNA were located on the heavy strand, except nad6 and eight tRNAs (glutamine, alanine, asparagine, cysteine, tyrosine, serine, glutamic acid and proline) transcribed from L strand. The genome exhibited an overlapping between atp8 and atp6 (2 bp), nad4 and nad4l (2 bp), tRNAIle and tRNAGln. (1 bp), tRNAThr and tRNAPro (1 bp). Around 157 bp, an intergenic spacer was identified. The overall GC-skews and AT-skews of the H-strand mitogenome were -0.35 and 0.079, respectively, revealing that the H-strand consisted of equal amounts of A and T and that the overall nucleotide composition was C skewed. All tRNA genes exhibited cloverleaf secondary structures, while the secondary structure of tRNASer lacked a discernible dihydrouridine stem. The phylogenetic analysis of available mitogenomes of Anabantiformes revealed a sister group relationship between Pristolepididae and Channidae. The whole mitogenome of Pristolepis rubripinnis will form a molecular resource for further taxonomic and conservation studies on this endemic freshwater fish.

Insulin-like growth factor signalling and its significance as a biomarker in fish and shellfish research.

The insulin-like growth factor signalling system comprises insulin-like growth factors, insulin-like growth factor receptors and insulin-like growth factor-binding proteins. Along with the growth hormones, insulin-like growth factor signalling is very pivotal in the growth and development of all vertebrates. In fishes, insulin-like growth factors play an important role in osmoregulation, besides the neuroendocrine regulation of growth. Insulin-like growth factor concentration in plasma can assess the growth in fishes and shellfishes and therefore widely applied in nutritional research as an indicator to evaluate the performance of selected nutrients. The present review summarizes the role of insulin-like growth factor signalling in fishes and shellfishes, its significance in aquaculture and in evaluating growth, reproduction and development, and discusses the utility of this system as biomarkers for early indication of growth in aquaculture.