Characterization of Kiss/Kissr system and expression profiling through developmental stages indicate kiss1 to be the active isotype in Clarias magur.

Kisspeptin (Kiss) and kisspeptin receptor (Kissr) system is a key regulator of GnRH expression in several vertebrates. The Indian catfish, Clarias magur, is popular in the Indian sub-continent, and a neo-type of the Asian catfish, C. batrachus. Catfish breeding is constrained as males do not release milt captivity with/without stimulation. Magur Kiss/Kissr system comprising of kiss1, kiss2, kissr1, and kissr2 genes was characterized for the first time. Full-length mRNA was sequenced using RACE PCR. Neighbor-joining tree of predicted proteins shows one clade of teleost orthologs. Magur whole genome (NCBI GenBank) has single copies of each gene, though yet unannotated/misannotated. Anomalies in the nomenclature of earlier sequences in GenBank were noted. Relative gene expression was profiled during various ontogenic stages, in six tissues including brain and gonads at maturity, and also in brains and gonads of premature and spent fish. Expression of gnrh1, gnrhr1, and gnrhr2 was estimated concomitantly. The kiss1 was the first to be twofold upregulated (P < 0.05) at 12 h post fertilization. Kiss/Kissr genes expressed primarily in the brain, ovary, and testis. Though kiss2 was 10 times higher than kiss1, only kiss1 showed significant modulation across stages and appears to be the active isotype that regulates GnRH in magur.

Molecular cloning and expression profiling of insulin-like growth factor 2 and IGF-binding protein 6 in Clarias magur (Hamilton 1822).

Growth is an important trait in aquaculture and the major genes that regulate it are Insulin-like growth factors (IGFs) and IGF binding proteins (IGFBPs). In this study, the full-length coding sequences of IGF2 and IGFBP6 genes in the Indian catfish Clarias magur were cloned and characterized. The full-length cDNA sequences of IGF2 and IGFBP6 were 885 bp (ORF 642 bp) and 928 bp (ORF 600 bp), encoding 213 and 199 amino acids, respectively. Bioinformatics analyses revealed that the magur IGF2 and IGFBP6 proteins are hydrophilic and secretory in nature. Sequence alignment with other teleosts and mammalian orthologues shows conservation of the functional domains. Gene expression analysis in 6 individuals each of high (298 ± 5.0 g) and low (210 ± 6.0 g) growth performing families showed significantly (p < 0.05) higher expression (2.5-3 fold) of IGF2, and lower expression (∼2.5 fold) of IGFBP6 in liver and muscle of fast-growing fish. This study suggests that IGF2 could be playing a major role in the growth regulation of magur. These genes and their expression patterns could be developed into growth-associated markers for magur and other catfishes.

Characterization of mitochondrial genome of Indian Ocean blue-spotted maskray, Neotrygon indica and its phylogenetic relationship within Dasyatidae Family.

The present study characterized complete mitochondrial genome of Blue-spotted maskray, Neotrygon indica and studied the evolutionary relationship of the species within the Dasyatidae family. The total length of the mitogenome was 17,974 bp including 37 genes and a non-coding control region. The average frequency of nucleotides in protein-coding genes was A: 29.1 %, T: 30.2 %, G: 13.0 % and C: 27.7 % with AT content of 59.3 %. The values of AT and GC skewness were -0.018 and -0.338, respectively. Comparative analyses showed a large number of average synonymous substitutions per synonymous site (Ks) in gene NADH4 (5.07) followed by NADH5 (4.72). High values of average number of non-synonymous substitutions per non-synonymous site (Ka) were observed in genes ATPase8 (0.54) and NADH2 (0.44). Genes NADH4L and NADH2 showed high interspecific genetic distance values of 0.224 ± 0.001 and 0.213 ± 0.002, respectively. Heat map analysis showed variation in codon usage among different species of the Dasyatidae family. The phylogenetic tree showed a sister relationship between the Dasyatinae and the Neotrygoninae subfamilies. Neotrygon indica formed as a sister species to the clade consisting of N. varidens and N. orientalis. Based on the present results, Neotrygon indica could have diverged from the common ancestor of the two latter in the Plio-Pleistocene. The present study showed distinct characteristics of N. indica from its congeners through comparative mitogenomics.

Complete mitochondrial genome of freshwater pearl mussel Lamellidens marginalis (Lamarck, 1819) and its phylogenetic relation within unionidae family.

BACKGROUND: Freshwater mussels play a key role in ecology and are often considered as ecological indicators. Conversely, these molluscs are one of the most threatened groups due to several anthropogenic factors. Knowledge of phylogenetic diversity would assist in formulating effective management and conservation measures. Lamellidens marginalis is one of the most widely used freshwater mussel for pearl production in India. The genomic resources for investigating its evolutionary relationship within the Unionidae family are lacking. METHODS AND RESULTS: In this study, the f-type mitochondrial genome of L. marginalis was sequenced using the Illumina sequencing platform. The length of the mitochondrial genome was 15,732 bp consisting of 23 tRNAs, 2 rRNAs and 13 protein coding genes. The arrangement of genes was UF1 type and gene overlap was observed between trnG and nad1. Comparative analysis with other Unionidae species showed a high divergence rate in nad6 followed by nad2 atp8 and nad5. The phylogenetic tree supported monophyly of the Unioninae subfamily and L. marginalis (Parreysiinae) formed a sister branch to this subfamily. The divergence time of the Parreysiinae from its most recent common ancestor (MRCA) was placed in the Mesozoic era. CONCLUSION: This information will be useful for the understanding the evolutionary pattern of the species of Parreysiinae subfamily.

Characterization of the complete mitochondrial genome of Neolissochilus hexastichus (McClelland, 1839).

The complete mitochondrial genome of the near threatened mahseer fish, Neolissochilus hexastichus, was characterized for the first-time using Ion Torrent NGS platform. The total length of the mitogenome was 16,538 bp including a standard set of 22 transfer RNAs (tRNAs), 2 ribosomal RNAs (rRNAs), 13 protein-coding genes and a non-coding control region. Twenty-eight of the 37 genes are located on the light strand and, the remaining nine genes are situated on the heavy strand. Phylogenetic analysis showed the sister relationship between N. hexastichus and N. hexagonolepis. The mitogenome could be useful for phylogenetics, population genetics, and conservation of the mahseers.

A new species of Stolephorus (Clupeiformes: Engraulidae) from the Bay of Bengal, India.

A new fish species, Stolephorus tamilensis sp. nov., is described from the East coast of India. The major distinguishing characters are 5-6 small needle-like pre-pelvic scutes on belly; maxilla tip pointed, reaching to border of operculum, concave and indented in the preoperculum; 25-28 gill rakers on lower lobe of the first branchial arch; dorsal fin without spine; 17-19 anal-fin rays. Moreover, S. tamilensis sp. nov. present higher average genetic divergence values at mitochondrial cytochrome c oxidase subunit I and 16S rDNA loci in comparison with congeners. Also, nucleotide diagnostic characters exclusive to S. tamilensis are identified. Neighbor-joining analysis revealed close relation between S. tamilensis  and S. andhraensis.

Molecular characterization and expression profiling of 17-beta-hydroxysteroid dehydrogenase 2 and spermatogenesis associated protein 2 genes in endangered catfish, Clarias magur (Hamilton, 1822).

The 17-beta-hydroxysteroid dehydrogenase 2 (17ß-HSD2) enzyme regulates steroid levels by the inactivation of estrogen and androgens. Spermatogenesis associated protein 2 (SPATA2) plays a vital role in spermatogenesis in vertebrates including fish. We report cloning and characterization of full cds of 17ß-HSD2 and SPATA2 genes in Clarias magur. The full-length cDNA sequences of 17ß-HSD2 and SPATA2 were 1187 bp (ORF 1125 bp) and 1806 bp (ORF 1524 bp) encoding 375 and 508 amino acids, respectively. Signal peptide analysis revealed SPATA2 is nonsecretory, while 17ß-HSD2 is a secretory protein. Hydropathy profiles showed both proteins are hydrophilic in nature. Tissue distribution of both the genes revealed high mRNA level of SPATA2 in all tissues examined indicating its wide range of expression. 17ß-HSD2 indicated higher expression in preparatory phase compared to spawning phase in ovary while it was opposite in case of testis. SPATA2 showed significantly higher expression in preparatory phase compared to spawning phase in both ovary and testis. Administration of OvatideTM (GnRH analog) resulted in upregulation of SPATA2 expression at 6 and 16 h post-injection while 17ß-HSD2 showed upregulation only at 6 h post-injection. To the best of our knowledge, this is a first report on characterization of 17ß-HSD2 and SPATA2 full-length cDNA in catfish.

Neotrygon indica sp. nov., the Indian Ocean blue-spotted maskray (Myliobatoidei, Dasyatidae).

The blue-spotted maskray, previously N. kuhlii, consists of up to eleven lineages representing separate species. Nine of these species (N. australiae, N. bobwardi, N. caeruleopunctata, N. malaccensis, N. moluccensis, N. orientale, N. vali, N. varidens, N. westpapuensis) have already been formally described and two (Indian Ocean maskray and Ryukyu maskray) remain undescribed. Here, the Indian Ocean maskray is described as a new species, Neotrygon indica sp. nov. Specimens of the new species were generally characterized on their dorsal side by a moderately large number of small ocellated blue spots, a low number of medium-sized ocellated blue spots, the absence of large ocellated blue spots, a high number of dark speckles, a few dark spots, and a conspicuous occipital mark. The new species formed a distinct haplogroup in the tree built from concatenated nucleotide sequences at the CO1 and cytochrome b loci. A diagnosis based on colour patterns and nucleotide sequences at the CO1 and cytochrome b loci is proposed. The distribution of N. indica sp. nov. includes the Indian coast of the Bay of Bengal, the Indian coast of the Laccadives Sea, and Tanzania. Considerable sampling effort remains necessary for an in-depth investigation of the phylogeographic structure of the Indian Ocean maskray.

Silencing and augmentation of IAG hormone transcripts in adult Macrobrachiumrosenbergii males affects morphotype transformation.

Morphotypic differentiation is the external manifestation of dominance hierarchy in Macrobrachium rosenbergii The intermediate morphotype orange claw (OC) male exhibits the highest growth rate and is subordinate in hierarchy to blue claw (BC) male while dominant on small male (SM). The present study was undertaken to examine the specific role of insulin-like androgenic gland (iag) hormone in morphotype differentiation of M. rosenbergii To achieve this, RNAi mediated knockdown as well as augmentation of iag transcripts were effected in ∼60 g OC males using plasmid-based constructs pcD-IAG-lh and pcD-IAGorf, respectively. The treatments were administered to animals maintained in isolation as well as in community. The knockdown plasmid construct that expresses iag-specific long hairpin RNA caused 16-fold reduction of iag transcripts in the SSN1 cell line in vitro When injected into OC males living in a community, 2.3-fold iag knockdown was recorded, while in isolated OC males it was 4.2-fold initially, but returned to normal subsequently. Compared with the respective controls, OC to BC transformations in the iag silenced animals were significantly lower in the community-reared group, while no difference was observed in the isolated animals. It is reported here for the first time that iag augmentation in OC males resulted in significantly higher OC to BC transformations, when animals were reared in community. This plasmid-based IAG knockdown approach could be developed into a low stress, feed or immersion treatment for controlling heterogeneous individual growth of M. rosenbergii males in aquaculture.

Expression analysis of Sox9 genes during annual reproductive cycles in gonads and after nanodelivery of LHRH in Clarias batrachus.

Transcription factor Sox9 plays a crucial role in determining the fate of several cell types and is a primary factor in regulation of gonadal development. Present study reports full-length cDNA sequence of Sox9a gene and partial coding sequence (cds) of Sox9b (two duplicate orthologs of Sox9 gene) from Clarias batrachus. The coding region of Sox9a gene encoded a peptide of 460 amino acids. The partial cds of Sox9b with the length of 558bp was amplified that codes for 186 amino acids. Quantitative Real-time PCR (qRT-PCR) analysis revealed that Sox9a and Sox9b mRNA expression was significantly higher in gonads and brain tissues. Furthermore Sox9a and Sox9b mRNA expression levels were high during preparatory and pre-spawning phases and decreased gradually with onset of spawning and post-spawning phases of reproductive cycles in gonads. Chitosan nanoconjugated sLHRH (CsLHRH) of particle size 133.0nm and zeta potential of 34.3mV were synthesized and evaluated against naked sLHRH (salmon luteinizing hormone-releasing hormone). The entrapment efficiency of CsLHRH was 63%. CsLHRH nanoparticles increased the expression level of Sox9 transcripts in gonads and steroid hormonal levels in blood of male and female. Thus, our findings clearly indicate that Sox9 genes play essential role during seasonal variation of gonads. Besides, the current study reports that sustained release delivery-system will be helpful for proper gonadal development of fish. To the best of our knowledge, till date no study has been reported on nanodelivery of sLHRH and their effect on reproductive gene expression in fish.

Molecular characterization and phylogeny of some mazocraeidean monogeneans from carangid fish.

Polyopisthocotylean monogenean parasites of fishes are highly host specific and have been used as an appropriate model to study the host-parasite co-evolution. In the present study, eight monogeneans of the order Mazocraeidea were characterized by nuclear 28S rDNA sequences and their phylogenetic relationship with other polyopisthocotylean species was investigated. Neighbour-joining, maximum parsimony, maximum likelihood and Bayesian Inference methods were used for phylogenetic reconstruction. The topology sustained by high bootstrap was: (((Hexabothriidae (Mazocraeidae (Discocotylidae (Diplozoidae (Diclidophoridae (Plectanocotylidae (Heteromicrocotylidae (Microcotylidae (Heteraxinidae), (Thoracocotylidae, Gotocotylidae (Gastrocoylidae (Allodiscocotylidae: Protomicrocotylidae))). In addition, we have also developed DNA barcodes (COI sequences) for six species and the barcodes clearly discriminated all the species. The polytomy within Protomicrocotylidae family is resolved in this study for the first time and it appears that within this family, Bilaterocotyloides species are basal compared to Neomicrocotyle and Lethacotyle species while the latter is the more derived.