The effects of bisphenol S exposure on the growth, physiological and biochemical indices, and ecdysteroid receptor gene expression in red swamp crayfish, Procambarus clarkii.

The experiment was conducted to investigate the effects of Bisphenol S (BPS) on growth, physiological and biochemical indices, and the expression of ecdysteroid receptor (ECR) of the red swamp crayfish (Procambarus clarkii). The gene encoding ECR was isolated from red swamp crayfish by homologous cloning and rapid amplification of cDNA ends (RACE). The ECR transcripts were 1757 bp long and encoded proteins of 576 amino acids. The quantitative real-time PCR (qRT-PCR) analysis showed that the ECR gene was expressed in various tissues under normal conditions, and the highest level was observed in the ovary and the lowest level was observed in the muscle (P < 0.05). Then, the experiment was designed with four different BPS concentrations (0, 1, 10, and 100 µg/L), BPS exposure for 14 days, three parallel groups, and a total of 240 red swamp crayfish. At 100 µg/L BPS, the survival rate, weight gain rate, and relative length rate were decreased significantly (P < 0.05). Malonaldehyde (MDA) content reached the highest level at 100 µg/L BPS. When BPS concentration was higher than 10 µg/L, the activities of superoxide dismutase (SOD) and catalase (CAT) were significantly lower than those of the control group (P < 0.05). The expression levels of the ECR gene in ovary, intestinal, gill, and hepatopancreas tissues were significantly increased after BPS exposure (P < 0.05). The ECR gene expression in ovaries and Y-organs was significantly higher than other groups in 10 µg/L BPS (P < 0.05). The expressions of the tumor necrosis factor -α (TNF-α) and interleukin-6 (IL-6) genes in the hepatopancreas gradually increased, and the highest expression was observed exposed in 100 µg/L BPS (P < 0.05). This research will provide novel insights into the health risk assessment of BPS in aquatic organisms.

Effects of ammonia exposure on anxiety behavior, oxidative stress and inflammation in guppy (Poecilia reticulate).

Ammonia is one of the most important aquatic environmental factors, which is of great concern. In order to evaluate the effect of ammonia on guppy (Poecilia reticulate), fish were exposed to increased concentrations (0, 12.50, 25.00, 41.67, 62.50 mg/L) of ammonia for 48 h. After exposure, we measured the anxiety behavior, antioxidant enzymes and pro-inflammation genes (TNF-α, IL-1ß and IL-6) of guppy. The results showed that ammonia stress induced fish anxiety, which was manifested by the increased latency to enter the upper half and decreased time spent in upper half compared with control fish. The guppy showed oxidative stress after 48 h of ammonia stress as evidenced by decreases in the activities of antioxidant enzymes and an increase in lipid hydroperoxide content. With prolonged ammonia stress, the expressions of HSP70, HSP90, TNF-α, IL-1ß and IL-6 mRNA at first had an increasing trend, and then decreased, all of which were significantly higher than the control levels at 12 h and 24 h after ammonia stress (P < 0.05). Ammonia significantly upregulated these genes mRNA levels after 48 h exposure, suggesting that heat shock proteins and innate immune system may try to protect cells from oxidative stress induced by ammonia stress. Our study showed that higher ammonia exposure induced oxidative stress in exposed fish, since inhibition of antioxidant enzymes activity and increases in lipid peroxidation, and inflammation occurred. Furthermore, the results will be helpful to understand the mechanism of ammonia toxicity in guppys.