| As a kind of emerging persistent organic pollutant (POPs), Perfluorooctane sulfonate (PFOS) has been widely concerned due to its global distribution, bioaccumulation and toxicological effects. Nowadays, research has focused on the effects of PFOS in mammal, but it’s almost empty in invertebrate.In the present study, PFOS was selected as poisonous substance, salinity was selected as influencing factor, Eriocheir sinensis was selected as the experimental animal, using the principle and method of ecological toxicology, involving morphology, biochemistry, physiology, and High performance liquid chromatography-tandem mass spectrometer (HPLC/MS-MS) techniques, comprehensive study accumulation characteristics and toxicity response to exposure to PFOS in Eriocheir sinensis, under different salinities. Our results would provide useful information for assessing ecotoxicological risks of PFOS on organisms living in coastal and estuarine environments. The main conclusions are as follows:1. Before the exposure test, the crabs were acclimatized to three different salinities (0,3 and 6% o) for 2 weeks. After adaptation, crabs for each salinity group were exposed to test media at different PFOS concentrations (0,500 and 5000μg/L). Crabs were subject to 21-day exposure followed by 7-day depuration. Sampling of crabs was done on days 0,7,21 during the exposure period, and on day 7 during the depuration period. None of PFOS group was used as control group, under different salinities.Bioaccumulation in edible partsResults show that, the background value of test crabs were relatively high, with 48.21±3.32 and 4.57±0.79 (ng/g, ww) in hepatopancreas and muscle, respectively, probably due to industrial pollution. Hepatopancreas showed stronger enrichment ability than muscle in 21-day exposure period, and could not recover to background level in a short time (7d). In the 500μg/L PFOS group, accumulation of PFOS in hepatopancreas increased with increasing salinity (P>0.05). While in the 5000μg/L PFOS group, accumulation of PFOS in hepatopancreas significantly higher at 6%o salinity level than that at other salinity levels (P<0.05). After 7 day depuration, hepatopancreas accumulation of PFOS in the 500μg/L PFOS group significantly lower at 3% o or 6%o salinity level than that at 0%o salinity level (P<0.05). The results suggest that accumulation and elimination of PFCs increased as salinity increased.Microstructural of hepatopancreas and gillsIn the present study, the hepatopancreas and gills microstructure damage were observed. The results showed that exposure to PFOS was found to result in several alterations in the microstructural of hepatopancreas and gills of Eriocheir sinensis, and the alterations of tissue damage increased with PFOS concentration increasing and time prolonging. The alterations of hepatopancreas included:increasing of tube lumen area of hepatopancreatic tube, swelling of pillar cell, declining of B cells, increasing number and size of vacuole. In the 5000μg/L PFOS group at 21 d, obvious vacuoles have located between basement and pillar cell, and basement membranes of hepatopancreatic tube have partly disrupted. Besides, cytoplasm pigmentation and nuclear condensation have occurred. At the same time, the alterations of gills included:thickening of gill lamellate, accumulation of haemolymph cells in the hemocoelic space and increasing of hemocoel area, abnormal of epthlium and cuticle. In the 5000μg/L PFOS group at 21d, vacuoles have occurred, and have observed further injuries in epthlium. There were no obvious differences among different salinity levels.2. Before the exposure test, the crabs were acclimatized to three different salinities (0,3 and 6% o) for 2 weeks. After adaptation, crabs for each salinity group were exposed to test media at different PFOS concentrations (0,500 and 5000μg/L). Sampling of crabs was done on days 1,4,7 during the exposure period.OsmoregulationTo determine the osmoregulation changes, we monitored serum osmolality, ion concentrations in serum, and gill Na+-K+-ATPase activity. Results show that, osmolality, Na+ concentration in serum, Na+-K+-ATPase activity were declined(P<0.05S), and serum K+ concentration was elevated in the 5000μg/L PFOS group at 7d(P<0.05). In addition, significant interactive effects between salinity and PFOS concentration on the serum K+ concentration and gill Na+-K+-ATPase activity were found, and this effect was time-dependent. The results suggest that increasing of water salinity may increase the risk of PFOS through changing the osmoregulation in Eriocheir sinensis.Respiration and energy conversionTo determine the respiration and energy conversion, we monitored blood physiological and biochemical index, hepatic glycogen content, and two key respiratory enzyme activities in gills (cytochrome c oxidase, CCO and lactate dehydrogenase, LDH). Results show that, CCO activity and hemocyanin content were declined (P<0.05) in the 5000μg/L PFOS group at 7d. During the 7d-test, LDH activity was stimulated and lactate levels were increased in PFOS-treated groups, at that raised glucose levels accompanying with decreased hepatic glycogen contents (P<0.05). In addition, significant interactive effects between salinity and PFOS concentration on hemocyanin content and gill CCO activity were found. The results suggest that, anaerobic metabolism was activated and hepatic glycogen was mobilized in Eriocheir sinensis, to meet the energy needs in response to PFOS. |
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