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ABSTRACT The abalone Haliotis diversicolor supertexta juveniles (shell length 3.51 ± 1.10 cm) were exposed to different concentrations of dissolved oxygen (DO) using the static renewal method at different salinity [...]

Abstract: Heavy metal lead (Pb2+) is a pollutant and causes severe toxicity when present in human tissues especially the nervous system. Recent reviews have suggested that Pb2+ can target Ca2+-related proteins within neurons and that Ca2+ channels might be a candidate for Pb2+ entry. This study''s main aim was to identify the functional entry pathway of Pb2+ into living cells. We firstly characterized the endogenous expression of Orai1 and STIM1 mRNA together with the level of thapsigargin (TG) stimulated capacitative Ca2+ entry in PC12 and HeLa cells; this was done by RT–PCR and time-lapse Ca2+ imaging microscopy, respectively. Our data supported Orai1 and STIM1 as contributing to store-operated Ca2+ channel (SOC) basal activity. Secondly, using the indo-1 quenching method with the SOC blocker 2-APB, we observed that Pb2+ was able to enter cells directly through unactivated SOCs without TG pretreatment. Thirdly, we further demonstrated that co-expression of Orai1 and STIM1 differentially enhanced SOC functional activity (4-fold with PC12 and 5-fold with HeLa cells) and Pb2+ entry (5- to 7-fold with PC12 and 2-fold with HeLa cells). Furthermore, after a 1 h of Pb2+ exposure, the depolarization- and histamine-induced Ca2+ responses were significantly decreased in both PC12 and HeLa cells in a dose-dependent manner. This result indicated that the decreased Ca2+ responses were, in part, due to Pb2+ entry. In summary, our results suggest that SOCs are responsible for Pb2+ permeation and that the Orai1–STIM1 protein complex formed by functional SOCs is one of the molecular components involved in Pb2+ entry. [Copyright &y& Elsevier]

Penaeus monodon (10.56 +/- 0.71 g) exposed individually to 0.026 (control), 0.774, 3.646, 7.004, 21.234 and 36.079 mM nitrate in 25 ppt seawater were examined for nitrate accumulation in hemolymph, gill, eyestalk, heart, foregut, midgut, hepatopancreas and muscle after 1, 3, 6, 12 and 24 h, respectively. Concentration of nitrate in the tissues increased directly with ambient nitrate concentration and exposure time except for muscle. Following 24-h exposure to 3.646 mM nitrate, nitrate concentrations measured in the muscle (0.202 micromol g(-1)), hepatopancreas (0.330 micromol g(-1)), heart (0.527 micromol g(-1)), foregut (0.632 micromol g(-1)), gill (0.927 micromol g(-1)), hemolymph (0.946 micromol ml(-1)), eyestalk (1.214 micromol g(-1)), and midgut (1.529 micromol g(-1)), respectively. The concentration of muscle nitrate was the lowest, and the concentration of midgut nitrate was the highest among the tissues tested. P. monodon following exposure to ambient nitrate at 21.234 and 36.079 mM, nitrate accumulation measured in the muscle (0.854 and 0.980 micromol g(-1)), hepatopancreas (1.139 and 1.552 micromol g(-1)), heart (1.468 and 1.879 micromol g(-1)), foregut (2.195 and 3.341 micromol g(-1)), gill (2.398 and 3.325 micromol g(-1)), hemolymph (3.327 and 3.948 micromol ml(-1)), eyestalk (3.461 and 4.264 micromol g(-1)) and midgut (3.343 and 5.239 micromol g(-1)), and never reached a plateau after 24 h.