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991.
Maria Andréasson Göran Dave 《Journal of Aquatic Ecosystem Stress and Recovery (Formerly Journal of Aquatic Ecosystem Health)》1995,4(4):221-230
Uptake and biliary excretion of metals were studied in rainbow trout, Oncorhynchus mykiss, exposed through spiked sediment to a mixture of seven heavy metals. Metal concentrations and toxicity of bile and blood plasma were used as indicators of exposure. Among the seven metals (Cd, Cr, Cu, Hg, Ni, Pb, and Zn) only three (Cu, Hg, and Pb) were concentrated in the bile (bile-plasma ratio >1). Bile-plasma ratios in the rainbow trout were similar to those found in rats for Cu and Hg. Daphnia magna bioassays were used to determine toxicity of bile and blood plasma in the same trout. Toxicity of bile and blood plasma increased after treatment with acid. An analysis of variance (ANOVA) showed that toxicity of bile and blood plasma to D. magna in metal-exposed trout was significantly correlated with (1) bile and blood plasma test concentration, (2) acid treatment of bile and blood plasma (hydrolysis of metal-plasma and metal-bile complexes) and (3) sediment concentration of metals during exposure of trout. In order to significantly detect the magnitude of the exposure to a xenobiotic the biomarker must respond in a dose- or time-dependent manner. Therefore, the potential use of bile toxicity as a biomarker of heavy metal exposure in fish is probably limited by the low bioconcentration of many of these toxicants in bile. 相似文献
992.
993.
Nyström L 《BMJ (Clinical research ed.)》2000,321(7262):647-648
994.
Anxiety disorders pose one of the largest threats to global mental health, and they predominantly emerge early in life. Social anxiety disorder, also known as social phobia, is the most common of all anxiety disorders. Moreover, it has severe consequences and is a disabling disorder that can cause an individual to be unable to perform the tasks of daily life. Social anxiety disorder is associated with the subsequent development of major depression and other mental diseases, as well as increased substance abuse. Although some neurobiological alterations have been found to be associated with social anxiety disorder, little is known about this disorder. Animal models are useful tools for the investigation of this disorder, as well as for finding new pharmacological targets for treatment. Thus, this review will highlight the main animal models of anxiety associated with social phobia. 相似文献
995.
Ligninolytic properties of different white-rot fungi 总被引:3,自引:0,他引:3
Summary Seven white-rot fungi were examined for the production of ligninase, manganese peroxidase and laccase. All these enzymes were found inTrametes gibbosa andTrametes hirsuta. Only manganese peroxidase and laccase were produced byPycnoporus cinnabarinus,Coriolopsis polyzona,Stereum hirsutum,Dichomitus squalens andGanoderma valesiacum. All fungi decolorized Poly B-411 and Indulin AT plates with low-N medium. The differences in enzyme pattern indicate that different species of fungi may employ different modes of lignin metabolism. 相似文献
996.
997.
Accompanying the CAM induction of Mesembryanthemum crystallinum L. grown in high salinity there are changes in the enzymes of carbon metabolism. However, there are no changes in the electron transport activities, Chla/b ratios or in the distribution of chlorophyll amongst the various pigment-protein complexes of isolated thylakoids. Hence with CAM induction there are no changes in the photochemical apparatus of M. crystallinum thylakoids. Despite comparable amounts of chlorophylla/b-proteins of photosystem II to those found in typical C3 sun plants, both the C3 and CAM M. crystallinum chloroplasts have relatively more photosystem II, and, concommitantly, less photosystem I complex. This is consistent with greater fluorescence emission at 685 and 695 nm, and lower emission at 735 nm (measured at 77 K) than typically found for C3 plants, whether sun or shade species. Photoinhibition of isolated C3 and CAM thylakoids by white light led to comparable decreases in electron transport capacities and fluorescence emission at 77 K with photosystem II being more affected than PSI. We suggest however, that the presence of more core PSII complexes relative to PSI complexes in this CAM-inducible plant, may provide an additional strategy to mitigate photoinhibition in the short-term. 相似文献
998.
In order to investigate the effect of large isoform of ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBPCO) activase (RuBPCO-A)
on photosynthesis, cDNA of the enzyme (rca) was transferred to rice cultivars (Oryza sativa f. japonica cv. Nipponbare) under the control of RuBPCO small subunit gene promoter (rbcS) via Agrobacterium tumefaciens-mediated transformation. Transgenic rice plants were identified by polymerase chain reaction (PCR) and Southern and Western
blot analyses. Net photosynthetic rate (P
N) values of the T1 transgenic lines 34 (T34) and 40 (T40) were 45.26 and 46.32 % higher than that of the control plants, respectively. At the
same time, their carboxylation efficiency and RuBPCO initial activity, quantum yield of electron transport in photosystem
2 (ΦPS2), and steady state photochemical fluorescence quenching (qP) increased. In addition, heading time of the transgenic rice was advanced. Thus increasing the amount of large isoform of
RuBPCO-A in the transgenic rice might have a stimulatory effect on both photosynthesis and plant growth. 相似文献
999.
C. Song Z. Liu Q. Xie H. Wang Y. Huang Y. Ruan D. Chen 《Applied Biochemistry and Microbiology》2017,53(5):524-532
A novel lipolytic enzyme-producing endophytic strain PC2 was successfully isolated from the seeds of an ideal bioenergy plant Pistacia chinensis Bunge. Based on the analysis of morphology and 16S rRNA sequence, bacterial strain PC2 was identified as a subspecies of Pseudomonas putida, therefore named as P. putida PC2. Whole-genome sequencing showed PC2 contained a 1224-nucleotide lipase gene (named lip-PC2) predicted to encode a 407-amino-acid protein. Purified lipases from both the original PC2 strain and heterologously expressed Escherichia coli were nearly 50 kD with specific activity of 9.48 U/mL. LIP-PC2 displayed the maximal activity at 50°C or pH 8.0, and maintained above 80% relative activity in the range of from 40 to 60°C or pH in the range of from 6.0 to 8.0, indicating thermostable and alkaline properties. Enzyme activity was enhanced by Mg2+, Na+ and Mn2+, but strongly inhibited by Cu2+, Zn2+ Co2+, EDTA as well as organic solvents and surfactants. Additionally, the analysis of amino acid sequence and structure indicated that LIP-PC2 was a novel member belonging to family I.3 of bacterial lipolytic enzymes and its catalytic triad was consisted of Ser-200, Asp-342 and His-374. 相似文献
1000.
M K Pulatova D E Filatov V L Sharygin L B Gorbacheva K V Gudtsova Z V Kuropteva T T Zhumabaeva V I Shamaev D B Korman 《Izvestiia Akademii nauk SSSR. Seriia biologicheskaia》1990,(5):737-748
Ribonucleotide reductase activity (RRA) has been studied in various tumors and spleens of tumor-bearing animals using EPR technique and biochemical methods. The effect of a number of biologically active compounds on RRA has also been studied. RRA in tumor and spleen increases during tumor growth. Inhibitory effect of irradiation, hydroxyurea, nitrosomethylurea and activatory effect of 5-nitrofurans and nitroimidazole derivatives on RRA has been observed. Regulatory factors of RRA and DNA synthesis in vivo have been discussed. 相似文献