RESUMO
The impact of contaminants on Copepod sp. and its molecular response is least explored, despite their abundance and dominance among invertebrates in aquatic environments. In the present investigation, Dioithona rigida, a cyclopoid zooplankton, was treated with selenium nanoparticles (SeNPs) to determine the associated biochemical changes, and the chronic exposure effects were recorded using transcriptomic analysis. It was found that, SeNPs were acutely toxic with a lethal dose 50% of 140.9 mg/L. The de novo assembled transcriptome of the copepod comprised 81,814 transcripts, which underwent subsequent annotations to biological processes (23,378), cellular components (21,414), and molecular functions (31,015). Comparison of the expressed transcripts against the treated sample showed that a total of 186 transcript genes were differentially expressed among the D. rigida treatments (control and SeNPs). The significant downregulated genes are coding for DNA repair, DNA-templated DNA replication, DNA integration, oxidoreductase activity and transmembrane transport. Similarly, significant upregulations were observed in protein phosphatase binding and regulation of membrane repolarization. Understanding the impact of SeNPs on copepods is crucial not only for aquatic ecosystem health but also for human health, as these organisms play a key role in marine food webs, ultimately affecting the fish consumed by humans. By elucidating the molecular responses and potential toxicological effects of SeNPs, this study provides key insights for risk assessments and regulatory policies, ensuring the safety of seafood and protecting human health from the unintended consequences of nanoparticle pollution.
The toxicity analysis in Dioithona rigida is the first of its kind as a copepod model for analysis on dietary fixation of metal toxicity at the trophic level. Since this copepod is a major zooplankton fed by fish and crustacean larvae in marine ecosystems, the toxicity analysis on this copepod will give us more insights of the trophic-level food transfer. As far as our knowledge, this is the first study that opted to construct the de novo transcriptomic pipeline for this copepod, treated with selenium nanoparticles. The effectiveness of this work may be further extrapolated to assess the effect of other metal nanoparticles in this model organism. Although the selenium toxicity in marine ecosystem is an established sector, through our combined approach of biochemical analysis and omics approach, the solid framework and comprehensive insight of the selenium toxicity in reproductive fitness and molecular changes has been studied. This study chose to seek a reliable alternative in the sense of new copepod model and omics approach to analyse the relevant metal nanoparticle toxicity in the marine ecosystem.
RESUMO
An aerobic microbial fuel cell (MFC) was designed to produce bio-electricity using cow manure-pretreated slurry (CM) and sewage sludge (SS). A comparative study of parametric effects on power generation for various parameters like feed ratio of wastes, pH of anode media, and electrode depth was conducted. This experiment aimed to identify the most important system parameters and optimize them to develop a suitable controller for a stable output. Power production reached its maximum at an electrode depth of 7 cm, a pH of 6, and a feed ratio of 2:1 in the CM + SS system before applying the controller. Response surface methodology (RSM) was practiced to explore the relationships between various parameters and the response using MINITAB software. The regression equation of the most productive system deduced from the RSM result has an R2 value of 85.3%. The results show that an ON/OFF controller works satisfactorily in this study. The highest energy-generating setup has a chemical oxygen demand (COD) removal efficiency of 45%. The morphology and content of the used wastes indicate that they can be recycled in other applications.