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B Utete C Phiri SS Mlambo N Maringapasi N Muboko TB Fregene 《African Journal of Aquatic Science》2018,43(1):1-15
Concentrations of aluminium, cadmium, chromium, cobalt, copper, iron, lead, nickel and zinc were determined in surface water, benthic sediments, and the gills, liver and stomach muscle tissues of Oreochromis niloticus and Clarias gariepinus in peri-urban lakes Chivero and Manyame, Zimbabwe. Five sites were sampled in each lake once per month in November 2015, February, May, August and November 2016. Pollution load index detected no metal contamination, whereas the geo-accumulation index reflected heavy to extreme sediment pollution, with Fe, Cd, Zn, Cr, Ni and Cu present in both lakes. Significant spatial temporal variations were detected for Al, Cr, Cu and Pb across sites within and between the two lakes. High Fe, Al and Cr concentrations in water and sediments in lakes Chivero and Manyame derive from geogenic background sources in addition to anthropogenic loads and intensity. Elevated concentrations of Al, Pb, Cu, Cd, Fe and Zn detected in gills, liver and stomach tissue of catfish corroborate concentrations in water and sediments, and pose the highest ecological and health risk for hydrobionts in lakes Chivero and Manyame. Contiguity of peri-urban lakes exposes them to similar threats, necessitating creative water management strategies, which ensure ecological continuity. 相似文献
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Cytoplasmic “Petite” Induction in Recombination-Deficient Mutants of Saccharomyces cerevisiae 下载免费PDF全文
Ethel Moustacchi 《Journal of bacteriology》1973,115(3):805-809
As compared to the original wild type, the induction of the cytoplasmic "petite" mutation by ultraviolet light and by the intercalating dye, ethidium bromide, is reduced in two mutants (rec4 and rec5) of Saccharomyces cerevisiae. These mutants are blocked in X rays or ultraviolet light-induced intragenic recombination. It then appears that the products of nuclear genes necessary for the completion of nuclear intragenic recombination events are also involved in steps of the metabolic chain which leads to the mitochondrial mutation, rho(-). 相似文献
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Antonysamy SS Aubol B Blaney J Browner MF Giannetti AM Harris SF Hébert N Hendle J Hopkins S Jefferson E Kissinger C Leveque V Marciano D McGee E Nájera I Nolan B Tomimoto M Torres E Wright T 《Bioorganic & medicinal chemistry letters》2008,18(9):2990-2995
Non-nucleoside inhibitors of HCV NS5b RNA polymerase were discovered by a fragment-based lead discovery approach, beginning with crystallographic fragment screening. The NS5b binding affinity and biochemical activity of fragment hits and inhibitors was determined by surface plasmon resonance (Biacore) and an enzyme inhibition assay, respectively. Crystallographic fragment screening hits with 1–10 mM binding affinity (KD) were iteratively optimized to give leads with 200 nM biochemical activity and low μM cellular activity in a Replicon assay. 相似文献
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Thiaporphyrins 2-8 were prepared as analogues of 5,20-diphenyl-10,15-bis[4-(carboxymethyleneoxy)-phenyl]-21,23- dithiaporphyrin (1) to examine the effect of structural modifications: substituent changes in meso aryl groups of dithiaporphyrins with one water-solubilizing group (2-5), dihydroxylation of a pyrrole double bond and reduction to dihydroxychlorins (6 and 7), and the removal of two meso aryl groups to give unsubstituted meso positions (8). The impact of these structural modifications was measured in both physicochemical (UV spectra, generation of singlet oxygen, lipophilicity, and aggregate formation) and biological properties (dark toxicity and phototoxicity, cellular uptake, and subcellular localization). Mono-functionalized porphyrins had much higher lipophilicity than di-functionalized porphyrin 1 and, consequently, formed more aggregates in aqueous media. The formation of aggregates might lower the efficiency of lipophilic porphyrins as photosensitizers. Interestingly, dihydroxylation of a core pyrrole group in the dithiaporphyrin core did not affect either the absorption spectrum or the efficiency for generating singlet oxygen. The phototoxicity of dihydroxydithiachlorins mainly depended on their intracellular uptake. The potent phototoxicity of 6, IC(50)=0.18muM, was attributed to the extraordinarily high uptake. The intracellular uptake of 6 was about 7.6 times higher than 1. In contrast, thiaporphyrin 8 with only two meso aryl groups was less effective as a photosensitizer, perhaps due to poorer uptake and a lower quantum yield for the generation of singlet oxygen. 相似文献
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To assess whether apoptosis occurs in pig brain granulomas due to Taenia solium cysticerci, brain tissues from 30 pigs naturally infected with T. solium cysticercosis were evaluated by terminal deoxynucleotidyl transferase-end labelling (TUNEL) staining. In addition, tissues were stained with CD3 marker to identify T lymphocytes. Examination of TUNEL-stained tissues showed apoptotic cells in early lesions that contained viable cysticerci. Apoptotic cells were primarily found interspersed with normal cell types, and were mostly located in the inflammatory infiltrate. Late or advanced granulomas with disintegrated scolices did not show TUNEL-positive cells. CD3+ cells were found in both early and advanced lesions and apoptosis mainly co-localized with CD3+ T lymphocytes. This suggests that these cells are constantly undergoing apoptosis and thus die as soon as they arrive at the site of infection. Apoptosis indeed may be one way by which T. solium cysticerci down-regulate the host's cellular immune response in early cysticercosis. Therefore, further research is needed to establish if other cells besides T-lymphocytes are also a target for destruction by cysticerci in early cysticercosis as well as studies to assess if cysteine protease is expressed by viable cysticerci in situ. 相似文献
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