Identification and characterisation of emerging fish pathogens Aeromonas veronii and Aeromonas hydrophila isolated from naturally infected Channa punctata.

Naturally infected Channa punctata exhibiting bacterial septicemic syndrome including ulcerations along with mortality records were collected from a fish farm in Assam during winter season (early November 2020 to early January 2021). The moribund fishes were subjected for bacterial isolation followed by identification of the bacteria. Two dominant emerging bacterial pathogens were identified as Aeromonas veronii (isolate ZooGURD-01) and Aeromonas hydrophila (isolate ZooGURD-05) by standard biochemical characterization and 16S rRNA and rpo B gene amplification. Re-infection experiments of both the bacterial isolates in healthy disease-free C. punctata showed similar symptoms to that of natural infection thus confirming their virulence. The LD50 calculated during challenge test for both the isolates ZooGURD-01 and ZooGURD-05 found to be pathogenic at 2.6 × 104 and 1.6 × 104 CFU/fish respectively. Further PCR amplification of specific virulent genes (aerolysin, hemolysin and enterotoxin) confirmed pathogenicity for both isolates. Histopathological examinations of liver and kidney in re-infection experiments showed prominent changes supporting bacterial septicaemia. Antibiotic sensitivity pattern showed that the isolates ZooGURD-01 and ZooGURD-05 were sensitive to 22 and 19 out of 25 antimicrobials respectively. The present study was the first report on the mortality of farmed C. punctata associated with natural infection caused by A. veronii and A. hydrophila with no record of pathogenicity of A. veronii in C. punctata.

Description of a new species of Mustura Kottelat (Teleostei: Nemacheilidae) from the Brahmaputra drainage, India.

Mustura subhashi, new species, is described from the Dikal River, a north bank tributary of the Brahmaputra drainage in Arunachal Pradesh. It is distinguished from all its congeners by having a colour pattern of 14-23 dark-greyish black to dark brown irregular bars on a greyish to pale beige body; pre-dorsal bars thin, numerous, wider than interspaces, weakly contrasted, uniting dorsally at lateral one-third or midway on flank to form thicker bars, coalescing further at lateral one-fifth and continuous on dorsum with contralateral bars; bars below dorsal fin exhibiting similar condition but slightly wider than pre-dorsal bars; post-dorsal bars thicker than anterior bars, wider than interspaces, sharply contrasted, rarely coalescing on flank; and a short bar along the caudal mid-line, rarely forming a blotch. Based on re-examination of the type specimens and additional materials, Mustura dikrongensis is confirmed as a species belonging to Mustura, and M. harkishorei is not sufficiently diagnosed from 'Nemacheilus' corica.

Psilorhynchus nahlongthai, a new fish species (Teleostei: Psilorhynchidae) from the Brahmaputra drainage, northeast India.

Psilorhynchus nahlongthai, a new psilorhynchid fish, is described from the Diyung River, a tributary to the Kopili River (itself a southern tributary of the Brahmaputra drainage) in Assam, northeast India. It is placed in the Psilorhynchus balitora species group and can be easily distinguished from all other members of this group by a combination of the following characters: dense and prominent tuberculation on the head region; thick and long pre- and post-epiphyseal fontanelles on the neurocranium; 9 + 8 caudal-fin rays; and 34 (24 + 10) vertebrae. Genetic divergence between P. nahlongthai and members of the P. balitora species group from the Brahmaputra and neighbouring drainages, with K2P distances ranging 3.7%-14.7% and 7.4%-20.7% in the mitochondrial COI and cyt b gene datasets respectively, support its report as a new species.

Impact of acid mine drainage on haematological, histopathological and genotoxic effects in golden mahaseer, Tor putitora.

The present study was carried out to evaluate sub-lethal mechanism of acid mine drainage toxicity in fingerlings (9.5 ± 2.4 cm) of golden mahseer, Tor putitora. Exposed fingerlings showed significant reduction (P < 0.01) in blood erythrocytes, neutrophils, thrombocytes, lymphocytes and leukocytes in contrast to increase in number of immature circulating cells. Hyperplasia, degeneration of glomeruli, presence of inflammatory cells and increased number of melanomacrophage aggregates, vacuolization of cell cytoplasm, hepatocyte swelling were marked in kidney and liver of fish. Ladder in, an increment of 180-200 bp of hepatic and kidney DNA, by electrophoresis were consistent with DNA damage. 10 day exposure to acid mine drainage resulted in reduction of double stranded DNA to 46.0 and 48.0 in hepatocytes and kidney cells respectively. Significant increase (P < 0.01) in tail length and percent tail DNA was evident by comet assay. The results suggest that exposure to acid mine drainage might cause irreversible damage to immune cells, tissue and DNA of fish, and this model of DNA damage may contribute in identifying novel molecular mechanism of interest for bioremediation application.

Glycyrrhizin functionalized CuS Nanoprobes for NIR Light-based therapeutic mitigation of acne vulgaris.

Acne Vulgaris or Acne is a multifactorial bacterial infection caused by Propionibacterium acne, leading to inflammation and decreased quality of life, especially in adolescence. Currently, antibiotics and retinoids are preferred for treating acne. However, their continuous usage may lead to anti-microbial resistance and other side effects. Therefore, research on developing effective strategies to reduce antimicrobial resistance and improve acne healing is ongoing. The current work reports the synthesis and evaluation of near-infrared light-absorbing copper sulfide (CuS) nanoparticles loaded with a biomolecule, Glycyrrhizin (Ga). The photothermal efficacy studies, and in-vitro and in-vivo experiments indicated that the Ga-CuS NPs generated localized hyperthermia in acne-causing bacteria, leading to their complete growth inhibition. The results indicated that the Ga-Cus NPs possess excellent antibacterial and anti-inflammatory properties in the acne and inflammatory models. This could be from the synergistic effect of CuS NPs mediated mild Photothermal effect and inherent pharmacological properties of Ga. Further detailed studies of the formulations can pave the way for application in cosmetic clinics for the effective and minimally invasive management of Acne-like conditions.

Isolation and characterization of two virulent Aeromonads associated with haemorrhagic septicaemia and tail-rot disease in farmed climbing perch Anabas testudineus.

Diseased Anabas testudineus exhibiting signs of tail-rot and ulcerations on body were collected from a fish farm in Assam, India during the winter season (November 2018 to January 2019). Swabs from the infected body parts were streaked on sterilized nutrient agar. Two dominant bacterial colonies were obtained, which were then isolated and labelled as AM-31 and AM-05. Standard biochemical characterisation and 16S rRNA and rpoB gene sequencing identified AM-31 isolate as Aeromonas hydrophila and AM-05 as Aeromonas jandaei. Symptoms similar to that of natural infection were observed on re-infecting both bacteria to disease-free A. testudineus, which confirmed their virulence. LC50 was determined at 1.3 × 104 (A. hydrophila) and 2.5 × 104 (A. jandaei) CFU per fish in intraperitoneal injection. Further, PCR amplification of specific genes responsible for virulence (aerolysin and enterotoxin) confirmed pathogenicity of both bacteria. Histopathology of kidney and liver in the experimentally-infected fishes revealed haemorrhage, tubular degeneration and vacuolation. Antibiotic profiles were also assessed for both bacteria. To the best of our knowledge, the present work is a first report on the mortality of farmed climbing perch naturally-infected by A. hydrophila as well as A. jandaei, with no records of pathogenicity of the latter in this fish.

Complete mitochondrial genome of nearly threatened freshwater ornamental fish, Microphis deocata and its phylogenetic relationship within Syngnathidae.

Microphis deocata (deocata pipefish), belonging to family Syngnathidae, is one of the important indigenous ornamental fish species listed as near threatened in the IUCN red list. Here, we first report the complete mitochondrial genome of deocata pipefish using Illumina next-generation sequencing platform. The total length of the mitogenome is 16,526 bp. It encompasses 13 protein coding genes, 2 ribosomal rRNAs, and 22 tRNAs. The WANCY region (a cluster of five tRNA genes) contains the 50 bp OL light strand origin of replication. Phylogenetic analysis of Syngnathidae revealed M. deocata to cluster with Oostethus manadensis, forming a sister group with Doryrhamphus japonicas and Dunckerocampus dactyliophorus. The mitochondrial genome sequence data generated in the present study will play an important role in population genetic analysis and developing conservation strategies for this species.

Schistura syngkai, a new fish species (Teleostei: Nemacheilidae) from Meghalaya, northeast India.

Schistura syngkai, a new stone loach, is described from the Twahdidoh Stream of Wahblei River (Surma-Meghna drainage) in Meghalaya, northeast India. It is unique among its Indian congeners in having a prominent dark-brown to blackish mid-lateral stripe about an eye diameter or more in width, overlain on 12-18 vertically-elongate black blotches on a golden-brown to amber body. Additionally, the species possesses an incomplete lateral line and a slightly emarginate caudal fin, and exhibits no apparent sexual dimorphism.

A new species of stone loach (Teleostei: Nemacheilidae: Schistura) from Arunachal Pradesh, India.

Schistura rebuw, new species, is described from the Kameng River, a north-bank tributary of the Brahmaputra, Arunachal Pradesh, India. The new species is easily distinguished from all known congeners in the Brahmaputra basin by its unique sexual dimorphism, specifically a suborbital slit in adult females, and a suborbital flap in adult males; and a colour pattern of 10-11 blackish bars on a greyish-beige body, the pre-dorsal bars mostly broken or incomplete, coalescing dorsally in a more or less alternate fashion.

Schistura larketensis, a new cavernicolous fish (Teleostei: Nemacheilidae) from Meghalaya, Northeast India.

Schistura larketensis, a new species of cavernicolous loach, is described from Khung, a limestone cave in Meghalaya, India. The species differs from Schistura papulifera, its only troglomorphic congener from northeast India, in having a smooth ventral surface of the head, the presence of a small cylindrical axillary pelvic lobe, and the presence of three pores in the supratemporal canal of the cephalic lateral-line system. Apart from these differences, the species can be immediately distinguished from all other species of Schistura from the Brahmaputra River and neighboring basins by the complete absence (or only vestigial presence) of eyes.

The complete mitochondrial genome of threatened chocolate mahseer (Neolissochilus hexagonolepis) and its phylogeny.

The chocolate mahseer (Neolissochilus hexagonolepis) is an important food and game fish of North Eastern India. To study the phylogenetic status we sequenced the complete mitochondrial genome of N. hexagonolepis. The mitogenome is 16,563 bp in length and composed of 13 protein coding genes, 22 tRNAs, 2 rRNAs and one putative control region. The overall base composition was A 31.8%, T 25.0%, G 15.8%, C 27.4% and A+T content 56.9%, G+C content 43.1%. The phylogenetic analysis using the complete mitochondrial genome revealed that the chocolate mahseer belonged to same clade of mahseer group of fishes but different from genera Barbus and Acrossocheilus. The present study will be helpful for the evolution and conservation genetic studies of N. hexagonolepis.