ABSTRACT
Deltamethrin is a classical pyrethroid insecticide that is frequently detected in aquatic environments and organisms. Furthermore, deltamethrin has been detected in samples related to human health and is a potential risk to public health. This study aimed to investigate the mechanism of cardiotoxicity induced by deltamethrin. Zebrafish were exposed to 0.005, 0.05, or 0.5 µg/L deltamethrin for 28 days. The results showed a significant reduction in male reproduction compared to female reproduction. Additionally, the heart rate decreased by 15.75 % in F1 after parental exposure to 0.5 µg/L deltamethrin. To evaluate cardiotoxicity, deltamethrin was administered to the zebrafish embryos. By using miRNA-Seq and bioinformatics analysis, it was discovered that miR-29b functions as a toxic regulator by targeting dnmts. The overexpression of miR-29b and inhibition of dnmts resulted in cardiac abnormalities, such as pericardial edema, bradycardia, and abnormal expression of genes related to the heart. Similar changes in the levels of miR-29b and dnmts were also detected in the gonads of F0 males and F1 embryos, confirming their effects. Overall, the results suggest that deltamethrin may have adverse effects on heart development in early-stage zebrafish and on reproduction in adult zebrafish. Furthermore, epigenetic modifications may threaten the cardiac function of offspring.
ABSTRACT
In this study, the cellulase gene celD from Clostridium thermocellum was cloned into expression vectors pET-20b(+) and pHsh. While high expression can be achieved by means of both these expression systems, only the pHsh expression system gives soluble proteins. By weakening the mRNA secondary structure and replacing the rare codons for the N-terminal amino acids of the target protein, the expression level of CelD was increased from 4.1 ± 0.3 to 6.4 ± 0.4 U ml(-1) in LB medium. Recombinant CelD was purified by heat treatment followed by Ni-NTA affinity. The purified CelD exhibited the highest activity at pH 5.4 and 60°C, and retained more than 50% activity after incubation at 70°C for 1 h. The cellulase activity of CelD was significantly enhanced by Ca(2+) but inhibited by EDTA. The favorable properties of CelD offer the potential for genetic modification of strains for biomass degradation. Presently, one of the major bottlenecks for industrial cellulase users is the high cost of enzyme production. The high level expression of soluble enzymes from the pHsh expression system offers a novel approach for the production of cellulases to be used in various agro-industrial processes such as chemical, food and textile.
