Effects of developmental exposure to individual and combined PFAS on development and behavioral stress responses in larval zebrafish.

Per- and polyfluoroalkyl substances (PFAS) are a class of synthetic chemicals known for their widespread use and persistence in the environment. Laboratory and epidemiological studies investigating these compounds have signaled their neurotoxic and endocrine-disrupting propensities, prompting further research into their effects on behavioral stress responses and their potential role as risk factors for stress-related disorders such as anxiety and depression. This study elucidates the ramifications of early developmental exposures to individual and combined PFAS on the development and behavioral stress responses of larval zebrafish (Danio rerio), an established model in toxicological research. Wild-type zebrafish embryos were enzymatically dechorionated and exposed to PFOS, PFOA, PFHxS, and PFHxA between 6 and 120 h post-fertilization (hpf). We targeted environmentally relevant concentrations stemming from the USEPA 2016 Hazard Advisory Limit (HAL, 0.07 µg/L) and folds higher (0.35, 0.7, 1.75, and 3.5 µg/L). Evaluations at 120 hpf encompassed mortality, overall development, developmental defects, and larval activity both at baseline stress levels and following exposure to acute stressors (acoustic and visual). Larval exposure to PFOA, PFOS, or PFHxS (0.07 µg/L or higher) elicited significant increases in mortality rates, which capped at 23.1%. Exposure to individual chemicals resulted in limited effects on overall development but increased the prevalence of developmental defects in the body axis, swim bladder, pigmentation, and eyes, as well as the prevalence of yolk sac and pericardial edemas. Larval activity at baseline stress levels and following exposure to acute stimuli was significantly altered. Combined exposure to all four chemicals intensified the breadth of developmental and behavioral alterations, suggesting possible additive or synergistic effects. Our findings shed light on the developmental and neurobehavioral disturbances associated with developmental exposure to PFAS at environmentally relevant concentrations, the added risks of combined exposures to these chemicals, and their possible role as environmental risk factors for stress-related disorders.

Amelioration of immune and digestive system through weed supplemented feed against Aeromonas hydrophila in Clarias gariepinus.

Aquaculture is one of the important globally growing industries. It serves as an important food source of protein for human beings. With the expanding demand for the fish and their products it has become extremely important to improve the aquaculture practices. Aquaculture in India has witnessed huge mortalities caused by bacteria, viruses, fungi, nematodes etc. Aquatic weeds plants are harmful for aquaculture in many ways. Present study is aimed to overcome the disease caused by Aeromonas hydrophila (fish pathogenic bacteria) through feed supplementation of two aquatic weed plants (Azolla pinnata and Ceratophyllum demersum). The fish were divided into 6 groups: experimental groups (fish fed on supplementary feed at 5% and 2.5% concentration for individual plant and challenged with bacteria), positive control (fish fed on non-supplemented feed and challenged with bacteria) and negative control (fish fed on non-supplementary feed and not challenged with bacteria). It was observed that supplemented feed enhanced both cell mediated and humoral immunity in fish. Therefore, we advocate that feed formulated with incorporation of Azolla pinnata and Ceratophyllum demersum leaf powder at 5% and 2.5% could be used to prevent disease caused by A. hydrophila or can be used to enhance fish health by boosting its immune system. The results of this study also showed an improved digestibility in fish fed on supplemented feed.