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51.
The effects of 4-nonylphenol on anti-oxidant enzyme (superoxide dismutase and catalase) activity in both gills and digestive gland and re-burrowing capability of the clam Tapes philippinarum were investigated after 7 days' exposure to various sublethal concentrations of nonylphenol (NP). NP caused a significant decrease in superoxide dismutase activity in both tissues from the lowest concentration tested, whereas no significant alteration with respect to controls was observed in catalase activity. NP effects on re-burrowing of clams were evaluated in two experiments. In the first, clams exposed to the highest NP concentrations showed a marked delay in re-burrowing 48 h after the end of exposure. Modifications in normal burrowing behaviour were also observed, suggesting that NP acts via narcosis and/or neurotoxic mechanisms. In the second experiment, the elapsed time for 50% of the exposed clams to re-burrow into the sediment (RT(50)) was also calculated in a 24-h re-burrowing response test. At the highest NP concentrations, it was not possible to estimate RT(50) values, as the percentage of clams showing complete burial was less than 50%. The present study demonstrates that NP causes oxidative stress by inhibiting superoxide dismutase activity and greatly affects the re-burrowing capability of T. philippinarum, even at environmentally realistic concentrations. 相似文献
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An assemblage of chernovite-(Y), As-bearing thorite, rooseveltite, and Cu and Fe arsenates has been revealed in Li-F granites, ongonites, and greisens of the Far East. The formation sequence of the above minerals is described in this paper. Chernovite-(Y) is a product of autometasomatic alteration of Li-F granite and ongonite, whereas other arsenates and As-thorite are products of greisenization. 相似文献
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Horia Mitrofan Constantin Marin Alin Tudorache Mădălina Vişan 《Pure and Applied Geophysics》2014,171(9):2315-2338
A monitoring operation conducted over more than seven years has been addressing chemical fluctuations displayed by several cool, low-discharge springs located close to the highly seismic Vrancea area (Romania). Those outflows compositions proved to be strongly controlled by binary, essentially isochemical mixing between a deep-origin brine and meteoric freshwater. By taking advantage of this particular setting, there have been constructed diagrams aimed at investigating how the groundwater-discharges Na–K–Mg geothermometric parameters fluctuated as a function of the chloride content (taken to be an estimator of the freshwater-induced dilution). We made use of the reciprocal algebraic relationships existing between the equations describing the Na–K–Mg geothermometric parameters “Na–K temperature” and “K–Mg temperature” on the one hand, and the so-called “maturity index” (MI) on the other. In an accordingly derived plot of MI against the logarithm of the chloride concentration, a series of data-points being quite uniformly off-set from the MI dilution-curve constructed for an apparently “regular” period, suggested that, episodically, all concerned springwaters were simultaneously subject to some similar changes in the controlling geochemical processes. One such modification intervened 3–4 months before the occurrence of the strongest earthquake ( \(M_{\text{w}} = 5.8\) ) of the hydrochemical monitoring period. The consequently derived interpretation was that then, the numerical values of certain geothermometric coefficients were likely altered: such a process could be consistent with changes in the alkali feldspars solubility relationships, possibly in response to episodic Al–Si complexing which might develop within a hypothesised, still active, exhumation-channel. 相似文献
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Lobach-Zhuchenko S. B. Kaulina T. V. Marin Yu. B. Yurchenko A. V. Skublov S. G. Egorova Yu. S. Galankina O. L. Sergeev S. A. 《Doklady Earth Sciences》2019,484(1):101-104
Doklady Earth Sciences - Data on the U–Pb (SIMS SHRIMP-II) age (3628 ± 38 and 2845 ± 65 Ma) of zircon from the inclusion of mafic granulite in gneiss–enderbites of the Bug... 相似文献
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The dissolution of calcified invertebrate skeletons releases an elaborate mixture of proteins, glycoproteins and polysaccharides. These skeletal matrix macromolecules are thought to play a major role in calcification and were widely used for phylogenetical studies. We tested the reactivity of water-soluble macromolecules from a wide range of invertebrate skeletons with two antisera raised against the shell matrix of the bivalve, Pinna nobilis. Projections of our results on the phylogenetical tree of Starobogatov (1992) show for the first time that, during evolution, antigenic determinants may degenerate in some stocks while they remain intact in others. The phylogenetic implications of these patterns of disjunct degeneration are discussed. 相似文献
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