Amiya Kumar Sahoo

Gonadotropin-Releasing Hormone (GnRH) is a crucial neuropeptide that regulates reproductive functions in vertebrates. The study identifies and characterizes (GnRH) in the brain of Tenualosa ilisha, an iconic and lucrative Clupeiform fish from River Ganga, India. The current study aimed to analyze the GnRH gene in T. ilisha using an in silico study. The GnRH gene of T. ilisha comprises a full-length nucleotide sequence of 605 base pairs with an open reading frame of 312 base pairs, which encodes 103 deduced amino acids (aa), respectively. It was found that leucine (L) is the most abundant amino acid in the GnRH protein. Additionally, the ligand interactions of the GnRH were analyzed using computational approaches. The structural validation showed an excellent stereochemical quality of the GnRH protein sequence, with over 88% of residues in Ramachandran plot-favored regions. The binding site prediction revealed 6 ligand-binding pockets, with the largest pocket containing 12 amino acids. After ADME screening, 16 drug-like compounds were docked to GnRH protein. Top five ligands N-Ac-(4-Cl-Phe)-Trp-Lys-AlaNH2, LHRH_LYS (6), Seabream_GnRH, Leuprolide, and LHRH_Des-tyr (5) had binding affinities ranging from −7.5 to −5.6 kcal/mol. The stable binding site was confirmed by 100 ns molecular dynamics simulations, with RMSD values below 10 Å and key residues retaining ligand contacts. The GnRH-protein resulted in the development of a suitable peptide sequence of T. ilisha, showing similarity with the similar anadromous American shad (Alosa sapidissima). This will certainly aid in future therapeutic and captive breeding advances, thereby fostering the culture and conservation of the wild species.

Small indigenous fish (SIF) production from wetlands provides nutritious food and supports the livelihood of the fishing community. The present study investigated the fish production trend, SIF diversity, and role of environmental and climatic parameters in Beledanga, a floodplain wetland in lower Ganges, through the sampling and collection of data from the local fishermen cooperative society. The fish catch composition in the wetland shifted after 2019, with the increased Ctenopharyngodon idella (grass carp) contribution from 11% to 17% due to the introduction of in situ seed-raising technology of an HDPE (high-density polyethylene) pen culture system. The fish fingerling stocking has a profound impact on fish production (R² = 0.60, p = 0.007). During the study period, 19 species of SIF were recorded, with a higher abundance observed in the monsoon season. The naturally occurring SIF contributed 16% of the total fish catch, with the highest catch in 2011 (11,970 kg). Water pH and phosphate content are the two most important environmental parameters that influence SIF. The generalized additive model (GAM) indicated that the optimum annual rainfall for fish production in the wetland was between 750 and 1250 mm. The average annual fish production of 43,017 kg through stocking and SIF support the livelihood and nutritional security of the fishers. As the SIF showed a decreasing trend of production, habitat protection, scientific stocking, and in situ enclosure culture are recommended for sustainable enhancement of fish production and to conserve the SIF diversity.

Escherichia coli strain, AKS1GF ICAR-CIFRI, was isolated from a thermally contaminated water with average water temperatures of 45°C ± 2.5°C in river Ganga, India. The draft genome sequence is of 4.7 MB consisting of 44 contigs. The strain contains 4,314 protein coding genes and 96 RNA genes.

The global rise of zoonotic bacteria resistant to multiple antimicrobial classes and the growing occurrence of infections caused by Aeromonas spp. resistant to β-lactam antibiotics pose a severe threat to animal and human health. However, the contribution of natural environments, particularly aquatic ecosystems, as ideal settings for the development and spread of antimicrobial resistance (AMR) is a key concern. Investigating the phenotypic antibiotic resistance and detection of β-lactamase producing Aeromonas spp. in Lamellidens marginalis, which inhabit all freshwater ecosystems of the Indian subcontinent, is essential for implications in monitoring food safety and drug resistance. In the present investigation, 92 isolates of Aeromonas spp. were recovered from 105 bivalves and screened for their antimicrobial resistance patterns. In vitro antibiotic resistance profiling showed a higher Multiple Antibiotic Resistance (MAR) index of 0.8 with the highest resistance against ampicillin/sulbactam (82%), while 58, 44, 39 and 38% of the isolates were resistant to cephalothin, erythromycin, cefoxitin and imipenem, respectively. PCR results revealed that these isolates carried the bla_TEM gene (94%), which was followed by the bla_CTX-M gene (51%) and the bla_SHV gene (45%). A combination of bla_SHV, bla_CTX-M, and bla_TEM genes was found in 17% of the isolates, indicating the presence of all three resistance genes. This is the first investigation which highlights the importance of multidrug-resistant Aeromonas spp. in L. marginalis. The identification of extended-spectrum-β-lactamases (ESBLs) genes demand the necessity of continuous surveillance and systematic monitoring, considering its potential health risks for both animals and human beings.

This study investigated the dietary immunomodulatory effects of Terminalia arjuna bark powder (TABP) in Labeo rohita, a freshwater fish model. Four iso-nitrogenous and iso-caloric diets containing graded levels of TABP (0, 1, 10, and 15 g/kg were fed to fish for 90 days, followed by a 10 day challenge with pathogenic bacteria Aeromonas hydrophila and Edwardsiella tarda. An integrated biomarker response (IBR) approach assessed the impact of TABP on hematological, adaptive, and humoral immune parameters, along with liver histomorphology. Dietary TABP at 10 g/kg significantly enhanced (p < 0.05) hematological indices (hemoglobin, red blood cell count, hematocrit), specific immune parameters (lysosomal enzyme activity, phagocytosis, respiratory burst), and non-specific immune parameters (serum lysozyme, alternative complement activity), and exhibited improvements in liver architecture consistent with the enhanced immune response. Broken line regression analysis showed 11.5 g/kg to be an optimum dose. However, at 15 g/kg, a compromised trend was observed in some parameters. These findings suggest an optimal dosage range for TABP’s immunomodulatory effects. The study highlights the potential of TABP as a natural immunomodulator in fish aquaculture. The improved immune response and concomitant liver health observed in Labeo rohita opens avenues for further research on TABP’s applicability in animal health, using fish as a model organism. Additionally, the IBR approach proved effective in evaluating TABP’s immunomodulatory properties, paving the way for similar studies on other natural products in aquaculture.

Editorial: Hilsa shad: progress in science and management