Biology subjects

Vijayan, J.

Publications and source records attributed to Vijayan, J..

5 recordsLinked to original sources

bioRxiv2025

Microbial source tracking using metagenomic analysis from Cochin Estuary

Microbial source tracking (MST) and metagenomics offer powerful insights into microbial ecosystems and pollution sources. This pilot study used metagenomics to identify microbial pollution sources in the Cochin Estuary (CE), a vital coastal ecosystem in southwest India. The CE faces significant microbial pollution, necessitating effective tracking for conservation. Bacterial community analysis via high-throughput sequencing was conducted to determine fecal pollution sources in CE waters. Samples included human, cow, dog, and goat feces, along with sewage, slaughterhouse, and domestic waste, alongside 24 water samples from eight sites across monsoon and non-monsoon seasons. DNA extraction and 16S rRNA (V3-V4) sequencing via Illumina MiSeq enabled MST analysis. Results indicated that sewage and domestic waste were the predominant contaminants, contributing to 50% of bacterial communities. Downstream sites were more polluted than upstream areas. Proteobacteria dominated estuarine waters, whereas Firmicutes and Bacteroidetes were prevalent in source samples. This study highlights the need for targeted remediation to protect the CEs environmental health. Importance of the studyThis study is essential for addressing microbial pollution in the Cochin Estuary (CE), a crucial Ramsar site facing contamination threats. Beyond identifying pollution sources, it provides valuable insights into seasonal variations in microbial composition, highlighting differences between monsoon (wet) and non-monsoon (dry) periods. It emphasizes the role of environmental factors such as conductivity, temperature, dissolved oxygen (DO), and salinity in shaping microbial communities. The study also employs advanced statistical tools like non-metric multidimensional scaling (NMDS) and principal coordinates analysis (PCoA) to assess microbial diversity and pollution patterns. Additionally, it underscores the significance of next-generation sequencing (NGS) in high-resolution microbial source tracking (MST). By integrating environmental parameters and microbial analysis, the study offers a comprehensive approach for monitoring estuarine health. These findings are crucial for policymakers, aiding in the development of targeted wastewater management and pollution mitigation strategies to protect CEs biodiversity and ecological balance.

microbiology↗

bioRxiv2024

Coenzyme M: An Archaeal Antioxidant as an Agricultural Biostimulant

Rising global food demand necessitates improved crop yields. Biostimulants offer a potential solution to meet these demands. Among them, antioxidants have shown potential to improve yield, nutritional quality and resilience to climate change. However, large-scale production of many antioxidants is challenging. Here, we investigate Coenzyme M (CoM), a small, achiral antioxidant from archaea, as a potential biostimulant, investigating its effects on growth and physiology. CoM significantly increased biomass of the model plant Arabidopsis thaliana in a concentration-dependent manner consistent with it being metabolized. In tobacco, CoM increased photosynthetic light capture capacity, consistent with observed growth improvements. Interestingly, this effect was independent of carbon capture rates. Furthermore, CoM promoted early-stage shoot growth in various crops species, including tobacco, basil, cannabis, and soybean. Our results suggest CoM is a promising, scalable biostimulant with potential to modify photosynthesis and enhance crop productivity. Key PointsO_LIAntioxidant application improves plant growth but is typically too expensive to use widely. C_LIO_LICoenzyme M is a small, easily made antioxidant of Archaeal origin. C_LIO_LIApplied exogenously, Coenzyme M conditionally increases plant biomass. C_LIO_LICoenzyme M represents an antioxidant with potential to be a widely used biostimulant. C_LI

plant biology↗

bioRxiv2023

Nitrogen starvation leads to TOR kinase-mediated downregulation of fatty acid synthesis in the algae Chlorella sorokiniana and Chlamydomonas reinhardtii

The accumulation of triacylglycerol (TAG) as a storage compound in eukaryotic algae has been the subject of extensive studies over the last 50 years. The model industrial alga Chlorella sorokiniana accumulates TAG and other storage compounds under nitrogen (N)-limited growth. Previously we used transcriptomics to explore the regulation of TAG synthesis in C. sorokiniana. Surprisingly, our analysis showed that the expression of several key genes encoding enzymes involved in plastidic fatty acid synthesis are significantly repressed. Metabolic labeling with radiolabeled acetate showed that de novo fatty acid synthesis is indeed downregulated under N-limitation. Likewise, inhibition of the Target of Rapamycin kinase (TOR), a key regulator of metabolism and growth, decreased fatty acid synthesis. We compared the changes in proteins and phosphoprotein abundance using a proteomics and phosphoproteomics approach in C. sorokiniana cells under N-limitation or TOR inhibition and found extensive overlap between the N-limited and TOR-inhibited conditions. We also identified changes in the phosphorylation levels of TOR complex proteins, TOR-kinase and RAPTOR, under N-limitation, indicating that TOR signaling is altered. Our results indicate that under N-limitation there is significant metabolic remodeling, including fatty acid synthesis, mediated by TOR signaling. We find that TOR-mediated metabolic remodeling of fatty acid synthesis under N-limitation is conserved in the chlorophyte algae Chlorella sorokiniana and Chlamydomonas reinhardtii.

plant biology↗

bioRxiv2021

Reactive oxygen species mediate thylakoid membrane remodeling and triacylglycerol synthesis under nitrogen starvation in the alga Chlorella sorokiniana

Many microbes accumulate energy storage molecules such as triglycerides and starch during nutrient limitation. In eukaryotic green algae grown under nitrogen limiting conditions, triglyceride accumulation is coupled with chlorosis and growth arrest. In this study we show that accumulation of reactive oxygen species (ROS) under nitrogen limitation in the microalga Chlorella sorokiniana is involved in thylakoid membrane remodeling, leading to chlorosis. We show that ROS accumulation under nitrogen limitation is an active process involving downregulation of expression of ROS-quenching enzymes, such as superoxide dismutases, catalase, peroxiredoxin, and glutathione peroxidase-like, and upregulation of enzymes involved in generating ROS, such as NADPH oxidase, xanthine oxidase and amine oxidases. Expression of enzymes involved in ascorbate and glutathione metabolism are also affected under these conditions. Quenching ROS under nitrogen limitation reduces TAG accumulation, adding additional evidence for the role of ROS signaling in the process.

plant biology↗

bioRxiv2020

Social decision making is influenced by size of shoal but not personality or familiarity in Deccan Mahseer (Tor khudree)

Shoals formed by many piscine species are fission-fusion societies where decisions to leave or join a group can have consequences on the fitness of individuals. Some important factors that determine shoal choice are shoal size, familiarity and species composition. However, individuals and species often exhibit distinct shoaling preferences. Individual differences in shoaling preferences may also be related to personality traits such as boldness and sociability. In this study, we examined the link between shoaling decisions and personality traits in a hatchery reared population of an endangered megafish, the Deccan Mahseer (Tor khudree). We found that this fish exhibits a distinct preference for larger shoals at ratios of 1:2 or greater. However, they did not prefer to associate with an isolated familiar individual over unfamiliar ones or with a member of their own species over an invasive species. Moreover, shoaling preferences in individuals did not correlate with their boldness or sociability. These results suggest that hatchery reared mahseers which are reintroduced into natural habitats may shoal with invasive species, negatively affecting their viability. Modifying social behaviour of mahseers by amending rearing practices may be a useful strategy to improve outcomes of restocking interventions.

animal behavior and cognition↗