Directorate of Coldwater Fisheries Research

Transcriptomics is the study of the entire set of RNA transcripts within a cell. It provides insights into the active and latent processes occurring at the subcellular level. Since its inception in the early nineties, it has revolutionized molecular biology and related fields. It has helped uncover the connections between genes and pathways, as well as their roles in physiology, biochemical processes, and disease. Advances in sequencing technologies have further resolved the complexity of cellular functions and provided a snapshot of the transcripts present in a cell at a given time. Over the past decade, transcriptomics has been extensively applied in aquaculture to identify and characterize transcripts associated with immune responses and physiological pathways. This approach allows researchers to study how transcript levels change across organisms, tissues, and cells in response to different stimuli, and thus permits the detection of broadly coordinated mechanisms. More recently, single-cell-based multi-omics techniques have revolutionized biological research. Although their application in fisheries science is still limited; however, it has enormous potential to address many unanswered research problems in this area. In this review, a broad idea about transcriptomics has been given with emphasis on single-cell isolation techniques and the available sequencing domain of single-cell omics. Additionally, we attempt to highlight a few of the important applications of single-cell and multi-cell transcriptomics in fisheries science.

Abstract Surfactants, or surface-active agents, are multifunctional amphiphilic compounds essential across numerous industrial and domestic applications. This review provides an in-depth analysis of surfactant chemistry, focusing on their diverse structures, interfacial behaviors, and self-assembly mechanisms, including micelle formation and emulsification. It outlines the classification of surfactants – anionic, cationic, non-ionic, and zwitterionic – while also exploring innovative types such as biosurfactants, sugar-based, lignin-derived, algal-based, and gemini surfactants. The growing emphasis on environmentally friendly and biodegradable surfactants sourced from renewable materials is highlighted, reflecting a shift away from conventional petroleum-derived options. The review examines key properties like surface tension reduction, wettability enhancement, foaming, detergency, and emulsification, linking them to their wide-ranging applications in sectors such as petrochemicals, pharmaceuticals, nanotechnology, paper manufacturing, and biotechnology. Finally, it underscores the crucial role of surfactants in fostering sustainable advancements and their potential for driving future technological innovations.

The rapid industrial development in the Indian capital region has led to significant waste generation, which, despite undergoing treatment prior to disposal, contributes substantially to water body contamination. Given the diverse nature of these wastes and their potential repercussions across the food chain, a study was conducted to evaluate heavy metal contamination levels in the Ganga and Yamuna Rivers of two major cities. Six heavy metals (Pb, Cd, Hg, Cu, Cr, and Zn) were analyzed in fish, water, and sediment samples by utilizing flame atomic absorption spectrophotometry (Avanta Σ) from March 2019 to February 2020. Results revealed distinct heavy metal distribution patterns, with Cr > Zn > Pb > Cu > Cd > Hg in the Ganga River and Zn > Cr > Pb > Cu > Cd > Hg in the Yamuna River for fish samples. Additionally, levels of Hg in Cyprinus carpio and Sperata oar from the Ganga River, and Pb, Cd, Hg, and Cr in Salmophasia bacaila and Mystus cavasius from the Yamuna River exceeded WHO/FAO permissible limits. In water samples, the predominant heavy metal sequences were Pb > Cu > Zn > Cr > Cd > Hg for the Ganga River and Cr > Zn > Pb > Cu > Cd > Hg for the Yamuna River, with Pb, Cr, Zn, and Cd surpassing WHO standards. Sediment analysis revealed varying heavy metal compositions, with Zn > Cr > Pb > Cu > Cd > Hg in the Ganga River and Cr > Zn > Pb > Cu > Cd > Hg in the Yamuna River. While drinking water and fish from the Ganga River were deemed safe for consumption, those from the Yamuna River were not. Given the toxic nature of heavy metals and their detrimental health impacts, regular monitoring and effective management strategies are imperative.

The intraspecific variation of Schizothorax richardsonii was estimated by analysing the morphometric characters. Schizothorax richardsonii is an indigenous Himalayan fish species, generally dwelling in fast flowing snow-fed rivers (8-22°C), streams and lakes and contributes significantly to the cold water fishery in the Himalayan region. Specimens were collected from five sampling sites including four natural lotic water bodies of the state Uttarakhand and one farmed stock of the target fish that is Kosi River, Alaknanda River, Chirapani stream, Gaula River and captive stock of DCFR Farm, Bhimtal. Phenotypic study was performed using Truss Network of 14 landmarks making 31 characters which reported high degree of significant morphometric heterogeneity among the populations with size within landmarks and shape as major factors of divergence in the selected ecosystems. Between-groups Principal Component Analysis revealed that the first and second principal components accounted for 91.2% and 5.4% of variance respectively. 94.5% of original grouped cases were correctly classified each original group for morphometric measurements of S. richardsonii and formed separate clusters. The results revealed that the candidate species has significant phenotypic heterogeneity between the stocks. We hypothesize that the marked variation in the stock is supporting the fact that environment plays a vital role in shaping the phenotypic characters.