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We investigated the short-term impact of environmental-induced stress on survival and neutral genetic diversity of recently settled juveniles of a damselfish, Dascyllus aruanus, using spatiotemporal caging experiments in various natural environmental conditions in Moorea (French Polynesia). Juveniles' mortality was followed at five study sites and overall four experiments, mortality rates ranged from 0 to 45%. Mortality rate and average daily water temperature were positively correlated ( P = 0.018). Juveniles' mortality rate and allelic richness estimated from ten microsatellite loci were negatively correlated ( P = 0.046). Together, an overdominance of heterozygotes was observed within hostile environments. These results suggest that an allelic richness loss may be expected as a direct consequence of unfavorable environmental conditions. Thus, a worrisome scenario on demographic and genetic consequences may be expected from habitat degradation in the context of global change and human pressure increases. [ABSTRACT FROM AUTHOR]

Classical antihistamines are potent rat mast cel degranulators active in the range of 0.1 to 2.0 m M at pH 8.4. No relationship between their potency as mast cell degranulators and their chemical structure nor their activity as inhibitors of peripheral H histamine receptors could be established. Halogenation of diphenhydramine and cylizine, but not of promethazine, increased their activity. The alkylamino side chain of phenothiazine does not seem to be essential for degranulation since toluidine blue and methylene blue, which lack it, are also active. Thionin, whose amino groups in the phenothiazine ring are not methylated, is inactive. The action of antihistamines on mast cells increases with increase of pH, suggesting that activity can mainly be attributed to the uncharged base. However, the ionized molecule must be active at lower pH too. Above certain concentrations, antihistmaines become inactive both at pH 7.0 and 8.4. At these higher concentrations, promethazine inhibits degranulation induced by chlorcyclizine or compound 48/80. An action not reversed by glucose. Mast cell degranulation by antihistamines does not seem to be caused by the ionized base acting inside the cell following pentration of the cell membrane by the lipid soluble uncharged molecule. [ABSTRACT FROM AUTHOR]