Molecular characterization, computational analysis and expression profiling of Dmrt1 gene in Indian major carp, Labeo rohita (Hamilton 1822)

Sexual dimorphism of fish morphology, physiology and behavior is diverse and complex in nature. Doublesex and mab-3 related transcription factor (Dmrt) is a large protein family whose function is sexual development and differentiation in vertebrates. Here, we report a full-length cDNA sequence of Labeo rohita (rohu) Dmrt1 of 907 bp length having 798 bp of open reading frame encoding 265 amino acids. The molecular weight of rohu DMRT1 protein was found to be 28.74 KDa and isoelectric point was 7.53. DMRT1 protein contains 23 positively and 24 negatively charged amino acids with a GRAVY score of -0.618. A characteristic DM domain was found in DMRT1 protein, which is a novel DNA-binding domain. Phylogenetic analysis showed maximum similarity with Cyprinus carpio when compared with DMRT1 of other vertebrates. Molecular docking study identified active sites to be targeted for drug designing. Rohu DMRT1 was observed to interact with other proteins such as FOXL2, CYP19a1a, AMH and SOX9a. Differential expression study revealed higher expression in testis tissue implying its role in male sex differentiation and testicular development. The information generated in the present work could facilitate further research to resolve the issues related to gonadal maturation and reproduction of commercially important aquaculture species.

Population structure and genetic diversity of hatchery stocks as revealed by combined mtDNA fragment sequences in Indian major carp, Catla catla

Catla catla is the second most important Indian major carp due to high growth rate and acceptance to consumers for food value. It is widely cultured in the Indian subcontinent as monoculture or polyculture. In the present study, genetic diversity among hatchery stocks (total 218 samples of catla) collected from different geographical regions of India was examined using mtDNA fragment sequence of Cyt b (306 bp) and D loop (710 bp). High numbers (57) of population specific haplotypes were observed in the present study. The results revealed significant genetic heterogeneity for the sequence data (F_ST = 0.27546, p < .05). Analysis of molecular variance revealed significant genetic differentiation among different catla populations. The information generated in present study could be useful to develop broad genetic base populations of catla.

Fabrication and characterization of chitosan conjugated eurycomanone nanoparticles: In vivo evaluation of the biodistribution and toxicity in fish

Chitosan nanoparticles (CNPs) have been proven considerable delivery agents due to their remarkable physicochemical properties. Present study reports the fabrication of CNPs by ionic gelation process and their characterization by different approaches. The constructed nanoparticles were successfully conjugated with eurycomanone with significant entrapment efficiency. Particle size of chitosan and chitosan conjugated eurycomanone nanoparticles were 126.2nm and 130nm respectively. Scanning electron microscopy showed that the particles were spherical in shape and well dispersed. Cross-linking between CNPs and eurycomanone (CENPs) were confirmed by Fourier-transform infrared (FTIR) spectroscopy. Fluorescent nanoparticles were prepared by using Rhodamine-6G dye, characterised by SEM and confirmed for conjugation by FTIR. Biodistribution of CENPs showed the presence of fluorescent nanoparticles in liver, kidney, testes and brain of C. magur. The toxicity of CENPs was evaluated by comparing the histological sections of catfish testes collected from treated and control group. No signs of toxicity were seen in testes after the delivery of CENPs. Molecular docking study revealed high spontaneous binding ability of chitosan with eurycomanone and aromatase enzyme. The study reports that CNPs can act as a stabilizing agent for eurycomanone formulation and could be a promising approach to increase the reproductive performance of the fishes.

Rapid recovery of complete mitogenome of Indian major carp, Catla catla from low depth paired end Illumina sequencing

Here we report the reconstruction of the catla (Catla catla) complete mitochondrial genome sequence from low depth paired end Illumina sequencing. The genome is of 16,597 bp in size. Similar to other vertebrate mtgenomes, it consists of 13 protein-coding genes, 22 tRNAs, 2 rRNAs and a putative control region. The present mtgenome is 3 bp longer than the earlier reported catla mtgenome from our laboratory. Majority of the mitochondrial genes are encoded by the H-strand. Phylogenetics analysis revealed that Catla catla is closer to Labeo rohita than other labeo species. Present study demonstrated the power of next generation sequencing towards hassle free and rapid sequencing of mitochondrial genomes of non-model organisms.

Molecular characterization of kisspeptin gene and effect of nano-encapsulted kisspeptin-10 on reproductive maturation in Catla catla

Kisspeptin, a member of the RF-amide-related peptide family, has emerged recently as an essential gatekeeper of various reproductive processes via its ability to activate kisspeptin receptors at puberty. In this study, the kiss1 gene and its receptor kiss1rb were cloned and characterized from the brain of Catla catla. Further, the effects of kissppetin-10 (K-10) and chitosan-encapsulated K-10 nanoparticles (CK-10) on gene expression were assessed. The full-length complementary DNA sequence of kiss1 is 754 bp with an open reading frame of 351 bp that encodes a putative protein of 116 amino acids. The kiss1rb complementary DNA is 1,280 bp long and contains a 5'-untranslated region of 30 bp, 3'-untranslated region of 149 bp, and an open reading frame (open reading frame) of 1,101 bp. The expression patterns of kiss1 and kiss1rb messenger RNA (mRNA) in basal tissues revealed that they are mainly expressed in the brain, pituitary gland, and gonads. CK-10 nanoparticles with a particle size of 125 nm and a zeta potential of 36.45 mV were synthesized and compared with K-10. Chitosan nanoparticles showed 60% entrapment efficiency for K-10. The mRNA expression of reproductive genes (GnRH, LH, and FSH) in fish injected with K-10 declined after 6 h, whereas those injected with CK-10 showed controlled and a sustained surge of mRNA expression of these genes with a peak at 12 h. Histologic examination of ovaries indicated a pronounced effect of CK-10 on maturation and gonadal development. The study reports that this sustained release delivery system will help in increasing the half-life of K-10 and other therapeutic protein drugs in the biological system. Besides, the nanoformulation developed in the present study may be useful for developing therapies against various reproductive dysfunctions in vertebrates.

Isolation, cloning, sequencing of brain type aromatase and its expression in male and female Wrasse, Pseudolabrus sieboldi

Pseudolabrus sieboldi, wrasse being a diurnal spawner provides a good opportunity to study the endocrine mechanism of estrogen formation in brain and gonads. Moreover, an extremely large amount of E2 was produced in serum and testis of wrasse. It is assumed that the presence of E2 may play a major role in diurnal gametogenesis in male fish. In this study brain type aromatase have been isolated, cloned and sequenced from the brain of wrasse. Further, the expression pattern of brain type aromatase in gonads and adult tissue of male and female fish have been analyzed. In addition, the diurnal expression pattern of brain type aromatase in both male and female fish brain during spawning season have been analyzed.The P450arom (br) was isolated, cloned and sequenced from both male and female bamboleaf wrasse. The P450arom (br) gene (1877 sequenced nucleotide) contains an ORF of 1470 bp, a 5'-UTR of 18 bp and at least 407 bp in 3'-UTR. The amino acid sequence homology in the coding region of wrasse P450arom (br) is high compared to that of medaka, Oryzias latipes (80%), rainbow trout type 2, Oncorhynchu mykiss (78.2%), fugu, Takifugu ribripes (78%) rainbow trout type 1, (76%), goldfish, Carassius auratus (66.8%) and zebrafish, Danio rerio (66.2%). Expression study reveals that P450arom (br) mRNA were most abundant in brains of both male and female fish throughout the day during the spawning season. RT-PCR study revealed that P450arom (br) was expressed in skin, anal fin and tail fin of both male and female wrasse. P450arom (br) was not detected at any time of the spawning day in either ovary or testis of wrasse.