Muscle Transcriptome Sequencing Revealed Thermal Stress-Responsive Regulatory Genes in Farmed Rohu, Labeo rohita (Hamilton, 1822).

Rohu, Labeo rohita, is one of the most important aquaculture species in the Indian subcontinent. Understanding the molecular-level physiological responses to thermal stress or climate change is essential. In the present work, transcriptome sequencing was carried out in the muscle tissue of the rohu in response to heat stress (35 °C) in comparison with the control (28 °C). A total of 125 Gb of sequence data was generated, and the raw-reads were filtered and trimmed, which resulted in 484 million quality reads. Reference-based assembly of reads was performed using L. rohita genome, and a total of 90.17% of reads were successfully mapped. A total of 37,462 contigs were assembled with an N50 value of 1854. The differential expression analysis revealed a total of 107 differentially expressed genes (DEGs) (15 up-, 37 down-, and 55 neutrally regulated) as compared to the control group (Log2FC > 2, P < 0.05). Gene enrichment analysis of DEGs indicates that transcripts were associated with molecular, biological, and cellular activities. The randomly selected differentially expressed transcripts were validated by RT-qPCR and found consistent expression patterns in line with the RNA-seq data. Several transcripts such as SERPINE1(HSP47), HSP70, HSP90alpha, Rano class II histocompatibility A beta, PGC-1 and ERR-induced regulator, proto-oncogene c-Fos, myozenin2, alpha-crystallin B chain-like protein, angiopoietin-like protein 8, and acetyl-CoA carboxylases have been identified in muscle tissue of rohu that are associated with stress/immunity. This study identified the key biomarker SERPINE1 (HSP47), which showed significant upregulation (~ 2- to threefold) in muscle tissue of rohu exposed to high temperature. This study can pave a path for the identification of stress-responsive biomarkers linked with thermal adaptations in the farmed carps.

Bactericidal activity of elastin-like polypeptide biopolymer with polyhistidine domain and silver.

In the present study, elastin-like biopolymer (ELP) composed of a polyhistidine domain has been investigated as a silver binding agent for antibacterial activity against Escherichia coli, a model test strain for Gram-negative bacteria for antibacterial assays of nanoparticles, and Vibrio harveyi, an opportunistic pathogen which cause mass mortality in shrimp Penaeus monodon reared in coastal aquaculture. The concentration dependent antimicrobial activity of ELPH-Ag on E. coli and V. harveyi was examined by agar well diffusion method and further confirmed through growth curves using spectrophotometer assisted absorption observations. The increased concentrations of ELP-Ag effectively checked the bacterial growth and increased the diameter of inhibition zone. The results showed a minimum inhibitory concentration of 37 µg/ml. This study has an application in formulating artificial protein based antibacterial in diverse fields of healthcare and management of disease in coastal aquaculture.