Digestive enzymatic patterns as possible biomarkers of endocrine disruption in the red mullet (Mullus barbatus): A preliminary investigation

Mechanistic toxicity and growth abnormalities mediated by subacute exposure to environmentally relevant levels of benzophenone-3 in clown anemonefish (Amphiprion ocellaris)

Benzophenone-3 (BP-3) is a UV filter that is ubiquitously present in the environment due to its photostability and degradation resistance and has wide applications in personal care products. BP-3 will eventually be discharged into the ocean. Studies shows BP-3 interferes with endocrine system of aquatic organisms, especially fish. However, the toxicity and mechanisms of subacute exposure of the coral reef fish to BP-3 remain elusive. Here, we exposed the one-month-old clown anemonefish to BP-3 at 1 and 10 μg/L for 14 and 28 days, respectively. After chronic exposure, the effects of BP-3 on the growth of clown anemonefish were investigated in terms of growth-related hormones, immune enzyme activity, digestive enzyme activity, transcriptional profiling of feeding- and obesity-related genes and digital RNA sequencing. The body weight in the BP-3 groups were abnormally increased (1 μg/L group in 14 days treatment and all groups in 28 days treatment), altered insulin content (28 days exposure), immune-related and digestive-related enzymatic activities. At the molecular level, BP-3 interferes with the expression of feeding- and obesity-related genes. Digital RNA sequencing analysis showed that BP-3 interferes with Kyoto encyclopedia of genes and genomes (KEGG) pathways related to growth, social behavior (learning behavior), Mitogen-Activated Protein Kinase (MAPK) signaling pathway, PI3K-Akt signaling pathway, and insulin secretion. Notably, in the insulin secretion, BP-3 induced Ca2+ up-regulation that may damage β cells. Growth abnormalities and social behavior (learning behavior) KEGG pathway disturbances may have potential impacts on populations of clown anemonefish. Our results reveal the toxicological effects of subacute exposure to BP-3, and provides insight into the effects and mechanisms of BP-3 on clown anemonefish growth.

Effects of fluoranthene on digestive enzymes activity and relative growth rate of larvae of lepidopteran species, Lymantria dispar L. and Euproctis chrysorrhoea L

Fluoranthene is one of the most abundant polycyclic aromatic hydrocarbon pollutants in the environment and it may accumulate in plant leaves which are the main food source for phytophagous insect species. The aim of this study was to establish the effects of dietary fluoranthene on specific activities of digestive enzymes and expression of their isoforms in the midgut, and the relative growth rates of Lymantria dispar and Euproctis chrysorrhoea larvae. Exposure to fluoranthene led to significantly decreased trypsin activity in the midgut of larvae of both species. Leucine aminopeptidase activity decreased significantly in the midgut of L. dispar larvae exposed to the lower concentration of fluoranthene, but that enzyme activity showed the opposite trend in E. chrysorrhoea larvae. There was no pollutant induced changes in lipase activity in L. dispar, while elevated enzyme activity was recorded in the midgut of E. chrysorrhoea larvae exposed to the lower concentration of fluoranthene. Different patterns of expression of enzyme isoforms were noticed. Relative growth rates of both species significantly decreased in fluoranthene treated larvae. These responses indicate to the significance of relationships between physiological changes and fitness-related traits in L. dispar and E. chrysorrhoea larvae affected by pollutant, and contribute to understanding the mechanisms of their adjustment to stressful conditions.

Effects of chronic exposure to cadmium and temperature, alone or combined, on the threespine stickleback (Gasterosteus aculeatus): Interest of digestive enzymes as biomarkers

The development of predictive, sensitive and reliable biomarkers is of crucial importance for aquatic biomonitoring to assess the effects of chemical substances on aquatic organisms, especially when it comes to combined effects with other stressors (e.g. temperature). The first purpose of the present study was to evaluate the single and combined effects of 90 days of exposure to an environmental cadmium concentration (0.5 μg L^-1) and two water temperatures (16 and 21 °C) on different parameters. These parameters are involved in (i) the antioxidant system (superoxide dismutase activity -SOD- and total glutathione levels -GSH-), (ii) the energy metabolism, i.e. energy reserves (glycogen, lipids, proteins) and digestive enzymes (trypsin, amylase, intestinal alkaline phosphatase -IAP-), and (iii) biometric parameters (weight, length, Fulton's condition factor, and the gonadosomatic index -GSI-) of threespine stickleback (Gasterosteus aculeatus). The second purpose was to determine the interest of the three digestive enzymes as biomarkers in comparison with the other parameters. The higher temperature (21 °C) impacted the anti-oxidant and energy reserve parameters. In liver, GSH levels increased on day 60, while SOD decreased on days 15 and 90, with a significant decrease of protein and lipid energy reserves on day 90. In muscle, the higher temperature decreased SOD activity only on day 90. G. aculeatus biometric parameters were also impacted by the higher temperature, which limited stickleback growth after 90 days of exposure. In female sticklebacks, the GSI peaked on day 60 and decreased sharply on day 90, while the highest values were reached at day 90 in the control groups, suggesting impaired reproduction in sticklebacks raised at 21 °C. These results suggest that 21 °C is an upper-limit temperature for long-term physiological processes in sticklebacks. In contrast, very low-concentration cadmium exposure had no effect on classical biomarkers (energy reserves, antioxidant parameters, biometric parameters). However, digestive enzymes showed an interesting sensitivity to cadmium, which was emphasized by high temperature. The activity of the three digestive enzymes decreased significantly on day 90 when sticklebacks were exposed to cadmium alone, while the decrease was stronger and was recorded earlier (from day 15) when they were exposed to the cadmium-temperature combination. Compared to conventional measurements, digestive enzymes responded rapidly. This could be an important advantage for them to be used as early warning tools to reflect the health status of organisms, particularly for trypsin and IAP activities.

Analysis and occurrence of some phenol endocrine disruptors in two marine sites of the northern coast of Sicily (Italy)

This study reports the occurrence of some endocrine disrupting chemicals in red mullet samples and sediments collected in two representative sites of the northern Sicilian coast (Italy). For this purpose, an improved method, using solid extraction and high-performance liquid chromatography analyses for the simultaneous determination of bisphenol A (BPA), 4-nonylphenol (4-NP) and 4-t-octylphenol (4-t-OP) in fish tissues and sediments, has been developed and validated. Method performance was demonstrated over the concentration range 0.1-200ng/mL, with detection limits from 0.06 to 0.1ng/mL. Recoveries ranged from 83.4% to 102.6%, with relative standard deviations of 7.7-14.0% for the entire procedure. Results showed that BPA, 4-t-OP and 4-NP were detected in all fish samples and sediments from two sampling sites, indicating that these chemicals have contaminated Mediterranean aquatic ecosystem and have accumulated in fish. The study provided more comprehensive fundamental data for risk assessment and contamination control of phenolic EDCs in aquatic environment.