Explore the vast range of titles available.

The study of the mitogenome of Neolissochilus pnar, the world’s largest cave fish, uncovered its structural features, gene content and evolutionary dynamics within mahseer. Its mitogenome is of 16,440 base pairs, resembling those of the teleost species and exhibits a high degree of conservation in genes arrangement. It comprises 37 mitochondrial genes, including 13 protein-coding genes (PCGs), 22 tRNA genes (tRNAs), 2 rRNA genes (rRNAs) and a control region. Notably, the distribution of genes on the L- and H-strands is consistent with that of the typical teleost. The study reveals the lengths and variations in PCGs in mahseer species, displaying a range from 164 to 11,404 bp. The tRNA and rRNA genes and the control region also demonstrate conservation among the species. A robust phylogenetic analysis, employing Bayesian and ASAP methods, supports the classification of N. pnar within the Neolissochilus genus and validates the taxonomic status of this species. Selection pressure analyses indicate positive selection in seven genes: COII , COIII, Cytb, ND1, ND2, ND5 and ND6. These findings suggest the dynamic nature of mitochondrial evolution in mahseer species. The purifying selection preserve essential mitochondrial functions, and additionally, the specific sites in ND5 and ND6 genes undergo episodic positive or diversifying selection, likely in response to environmental changes or selective pressures. In conclusion, this research enriches our understanding of N. pnar visa-vis other mahseers’ mitogenomes, pointing to its possible mitogenome evolution to adaptation to cave environment.

The present study, for the first time, reported twelve A2M isoforms in Tenualosa ilisha, through SMRT sequencing. Hilsa shad, T. ilisha, an anadromous fish, faces environmental stresses and is thus prone to diseases. Here, expression profiles of different A2M isoforms in four tissues were studied in T. ilisha, for the tissue specific diversity of A2M. Large scale high quality full length transcripts (>0.99% accuracy) were obtained from liver, ovary, testes and gill transcriptomes, through Iso-sequencing on PacBio RSII. A total of 12 isoforms, with complete putatative proteins, were detected in three tissues (7 isoforms in liver, 4 in ovary and 1 in testes). Complete structure of A2M mRNA was predicted from these isoforms, containing 4680 bp sequence, 35 exons and 1508 amino acids. With Homo sapiens A2M as reference, six functional domains (A2M_N,A2M_N2, A2M, Thiol-ester_cl, Complement and Receptor domain), along with a bait region, were predicted in A2M consensus protein. A total of 35 splice sites were identified in T. ilisha A2M consensus transcript, with highest frequency (55.7%) of GT-AG splice sites, as compared to that of Homo sapiens. Liver showed longest isoform (X1) consisting of all domains, while smallest (X10) was found in ovary with one Receptor domain. Present study predicted five putative markers (I-212, I-269, A-472, S-567 and Y-906) for EUS disease resistance in A2M protein, which were present in MG2 domains (A2M_N and A2M_N2), by comparing with that of resistant and susceptible/unknown response species. These markers classified fishes into two groups, resistant and susceptible response. Potential markers, predicted in T. ilisha, placed it to be EUS susceptible category. Putative markers reported in A2M protein may serve as molecular markers in diagnosis of EUS disease resistance/susceptibility in fishes and may have a potential for inclusion in the marker panel for pilot studies. Further, challenging studies are required to confirm the role of particular A2M isoforms and markers identified in immune protection against EUS disease.

The freshwater aquaculture species, Cirrhinus mrigala , commonly known as mrigal, holds significance in the carp-dominated aquaculture system, globally. Despite constituting 1.08% of the total freshwater aquaculture production, mrigal is the third most important Indian major carp. However, its genome and associated information is not available. This study aims to address this gap by generation high quality genome assembly using PacBio long reads, Illumina short reads and Hi-C scaffolding. The characterization of assembled highly contiguous genome, 1.057 Gb in size, revealed 39,091 genes with functional annotations. The orthology analysis based on direct orthologs and single copy ortholgs places C. mrigala in a distinct position within the Otophysi clade. Additionally, the study delves into Hox gene clusters, identifying 38 Hox genes distributed in seven clusters. The present genomic information offers potential applications for sustainable aquaculture management, including selection programs for economic traits.

Clarias dussumieri , a near threatened freshwater catfish, is endemic to peninsular India and has aquaculture potential. Unlike its sister species, C. magur , the male fish needs not be sacrificed during captive breeding. Thus, the generation of genomic information of this species becomes significant for effective genome mining through the bioprospecting of novel genes for important production traits. In this study, the genome assembly was undertaken to address this gap by generating high quality chromosome level genome assembly using PacBio long reads and Hi-C scaffolding. The total assembled genome was found to be 918.72 Mb in size and showed 95.23% completeness. Its characterization exhibited 41.46% repeats, 1,174,725 SSRs and 25,369 predicted genes with functional annotations. The Single copy orthologs analysis placed C. dussumieri in a distinct position with C. magur . The comprehensive genomic information offers resources for comparative genomics with other Clarias species for improvement of economic traits.

Aphanomyces invadans , the causative agent of epizootic ulcerative syndrome, is one of the most destructive pathogens of freshwater fishes. To date, the disease has been reported from over 160 fish species in 20 countries and notably, this is the first non-salmonid disease that has resulted in major impacts globally. In particular, Indian major carps (IMCs) are highly susceptible to this disease. To increase our knowledge particularly with regards to host immune response against A. invadans infection in a susceptible host, the gene expression profile in head kidney of A. invadans -infected and control rohu, Labeo rohita was investigated using RNA sequencing. Time course analysis of RNA-Seq data revealed 5608 differentially expressed genes, involved among others in Antigen processing and presentation, Leukocyte transendothelial migration, IL-17 signaling, Chemokine signaling, C-type lectin receptor signaling and Toll-like receptor signaling pathways. In the affected pathways, a number of immune genes were found to be downregulated, suggesting an immune evasion strategy of A. invadans in establishing the infection. The information generated in this study offers first systematic mechanistic understanding of the host–pathogen interaction that might underpin the development of new management strategies for this economically devastating fish-pathogenic oomycete A. invadans .

Neolissochilus pnar , identified as the world’s largest cave fish, belongs to the family Cyprinidae and is endemic to one of India’s biodiversity hotspots, specifically in the limestones caves of Meghalaya, India. This species is notably different from its closely related counterpart, Neolissochilus hexastichus , primarily in its lack of pigmentation and the absence or reduction of eyes. While juvenile N. pnar may have small or reduced eyes, adults exhibit a absence of external ocular features. Thus, genome sequence resources of this species would be an effective tool for bioprospecting and mining of novel genes responsible for the important traits. In this study, genome sequencing was done through long reads technology (PacBio) and high quality draft genome assembly, of 1.56 Gb in size with 1,423 contigs, N 50 of 18.990 Mb was generated, which showed 99% (BUSCO) genome completenes. The genome assembly contains 44.30% repetitive elements, 1,416,376 SSRs, and 37,559 functionally annotated genes. Single-copy orthologs (SOGs) analysis indicated N. pnar to be in the same cluster with other cave dwelling Cyprinids used in the sudy.The extensive genomic information generated in present study would be a useful resource for understanding evolutionaly significance and genes governing the traits including the body colour and eye development in Mahseer species.

Genetic diversity and population structure in Indian featherback fish, Chitala chitala (Hamilton, 1822) was investigated by combined analyses of two full mitochondrial genes, ATPase 6/8 and Cytochrome b. A total of 403 individuals, collected from 14 rivers yielded 61 haplotypes. Hierarchical partitioning analysis identified 19.01% variance ‘ among ’ and 80.99% variance ‘ within groups and populations ’. The mean coefficient of genetic differentiation (F ST ) was observed to be significant 0.26 (p < 0.05). Mantel tests rejected the hypothesis that genetic and geographic distances were correlated. The patterns of genetic differentiation, AMOVA and principal coordinate analyses indicated that natural populations were sub-structured and comprised of four genetic stocks of C. chitala in Indian rivers. The results also supported the higher resolution potential of concatenated gene sequences. The knowledge of genetic variation and divergence, from this study, can be utilized for its scientific conservation and management in the wild.

Background Full length transcriptomes, achieved through long-read sequencing, along with the isoform analysis can reveal complexities in the gene expression profiles, as well as annotate the transcriptomes of non-model organisms. Methods and result Full length transcripts of brain transcriptome of Tenualosa ilisha , Hilsa shad, were generated through PacBio single molecule real-time sequencing and were characterized. A total of 8.30 Gb clean reads were generated, with PacBio RSII, which resulted in 57,651 high quality consensus transcripts. After removing redundant reads, a total of 19,220 high-quality non-redundant transcripts and 17,341 full length ORF transcripts were classified to 7522 putative ortholog groups. Genes involved in various neural pathways were identified. In addition, isoform clusters and lncRNAs were discovered, along with Hilsa specific transcripts with coding frames and 29,147 SSRs in 944 transcripts (1141 annotated). Conclusion The present study provided, for the first time, a comprehensive view of the alternative isoforms of genes and transcriptome complexity in Hilsa shad brain and forms a rich resource for functional studies in brain of this anadromous fish.

Fish stocks that are grown under diverse environmental conditions have different biometric relationships and growth patterns. The biometric length-weight relationship (LWR) is an essential fishery assessment tool, as fish growth is continuous and depends on genetic and environmental factors. The present study attempts to understand the LWR of the flathead grey mullet, Mugil cephalus Linnaeus, 1758, from different locations. The study area encompassed its distribution in the wild across freshwater location (one), coastal habitats (eight locations), and estuaries (six locations) in India to determine the relationship between various environmental parameters. Specimens ( n = 476) of M. cephalus were collected from commercial catches and the length and weight of individual specimens were recorded. Monthly data from the study locations were extracted for nine environmental variables from the datasets downloaded from the Physical Oceanography Distributed Active Archive Center (PO.DAAC) and the Copernicus Marine Environment Monitoring Service (CMEMS) over 16 years (2002 to 2017) on the Geographical Information System platform. The parameters of the LWR, intercept ‘a’ and slope or regression coefficient ‘b’, varied from 0.005321 to 0.22182 and 2.235 to 3.173, respectively. The condition factor ranged from 0.92 to 1.41. The partial least squares (PLS) score scatter plot matrix indicated differences in the environmental variables between the locations. PLS analysis of the regression coefficient and environment parameters revealed that certain environment variables viz. , sea surface temperature, salinity, dissolved oxygen, nitrate, and phosphate, played a positive role. However, chlorophyll, pH, silicate, and iron played a negative role in influencing weight growth across various locations. The results revealed that the M. cephalus specimens from three locations, Mandapam, Karwar, and Ratnagiri, possessed significantly higher fitness to their environment than those from the other six locations. The PLS model can be used to predict weight growth under the various environmental conditions of different ecosystems. The three identified locations are useful sites for the mariculture of this species considering their growth performance, the environmental variables, and their interactions. The results of this study will improve the management and conservation of exploited stocks in regions affected by climate change. Our results will also aid in making environment clearance decisions for coastal development projects and will improve the efficiency of mariculture systems.

Chitala chitala (Hamilton, 1822) is an economically important food fish species occurring throughout Indian rivers, which also has ornamental value. This study focuses on morphological variations in C. chitala from seven river basins across India namely; Son, Tons, Ken, Brahmaputra, Ganga, Gomti and Gandak. A truss network was constructed by interconnecting nine landmarks to generate 36 morphometric variables extracted from digital images of specimens sampled from the study locations. Transformed truss measurements were subjected to principal component analysis (PCA), canonical discriminant function analysis (CDFA) and discriminant analyses of principal components (DAPC). DAPC function coefficients performed much better in capturing the variation pattern and discrimination between the rivers which was not achieved using CDFA. Eight truss variables were identified with significant and highest loading for truss variables on principal components and coefficients on discriminant function from DAPC contributing to maximum variation between the rivers. Performance graph and functional distribution of identified truss variables clearly indicated distinction between the rivers. Thin plate spline analysis and procrustes shape analysis further showed the variation in morphology between specimens across the rivers. The significant parameters differentiating specimens from different rivers were linked to dorsal fin origin, the base of the pectoral fin and the perpendicular point on the anal fin from the dorsal fin origin. Variation in the hydrodynamics of the rivers studied might be possibly affecting the fin kinematics and consequently leading to adaption seen as phenotypic variation in C. chitala . The results showcased in the present study shall help in better understanding of intra-specific diversity which is significant for management and conservation of a species.