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武汉东湖水生植被及其恢复途径探讨 总被引:4,自引:0,他引:4
1992~1993年对武汉东湖三个主要湖区(郭郑湖、汤林湖和牛巢湖)水生植被的调查表明,该湖区共有水生植物32种,优势种为大茨藻、狐尾藻、苦草和菱。金鱼藻呈不断扩大的趋势。植被类型可分为11个群丛,植被面积约为0.65km ̄2,总生物量为1236.39t(湿重),植被带状分布仅见于汤林湖北部和其他部分湖汊。汤林湖和牛巢湖水生植被正处于自然恢复演替阶段。 相似文献
966.
The surface disinfectant effect of glutaraldehyde in the gas-aerosol phase was investigated at different relative humidities and temperatures. At a gas-aerosol concentration of 15 to 20 mg/m3 and a relative humidity of about 80%, glutaraldehyde had a good disinfectant effect against both vegetative bacteria (decimal reduction time, less than 5 min) and bacterial spores (decimal reduction time, less than 45 min). In spite of its low volatility, glutaraldehyde was more effective than formaldehyde when the two substances were compared on an "added amount" basis. 相似文献
967.
Lucia Vergauwen Dries Knapen An Hagenaars Gudrun De Boeck Ronny Blust 《Journal of comparative physiology. B, Biochemical, systemic, and environmental physiology》2013,183(1):109-121
The zebrafish has become a valuable vertebrate model organism in a wide range of scientific disciplines, but current information concerning the physiological temperature response of adult zebrafish is rather scarce. In this study, zebrafish were experimentally acclimated for 28 days to 18, 26 or 34 °C and a suite of non-invasive and invasive methods was applied to determine the thermal dependence of zebrafish physiological condition. With decreasing temperature, the metabolic rate of zebrafish decreased, as shown by the decreasing oxygen uptake and ammonia excretion rates, limiting the critical swimming speed, probably due to a decreased muscle fibre power output. In response to exercise, fuel stores were mobilized to the liver as shown by the increased hepatosomatic index, liver total absolute energetic value and liver carbohydrate concentration but due to the low metabolic rate they could not be adequately addressed to power swimming activity at 18 °C. Conversely, the increased metabolic performance at high temperature came with an increased metabolic cost resulting in decreased energy status reflected particularly well by the non-invasive condition factor and invasive measures of carcass protein concentration, carcass total absolute energetic value and liver carbohydrate concentration. We showed that the combined measurement of the relative condition factor and critical swimming speed is a powerful non-invasive tool for long-term follow-up studies. Invasive methods were redundant for measuring general energy status but they provided detailed information concerning metabolic reorganization. With this study we proved that the usefulness of the zebrafish as a model organism can easily be expanded to include physiological studies and we provided a reference dataset for the selection of measures of physiological responses for future studies using the zebrafish. 相似文献
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Qiulin Wu Lixia Gou Shuangjun Lin Jingdan Liang Jun Yin Xiufen Zhou Linquan Bai Derong An Zixin Deng Zhijun Wang 《Biochimie》2013
Calcimycin is a rare divalent cation specific ionophore antibiotic that has many biochemical and pharmaceutical applications. We have recently cloned and sequenced the Streptomyces chartreusis calcimycin biosynthesis gene cluster as well as identified the genes required for the synthesis of the polyketide backbone of calcimycin. Additional modifying or decorating enzymes are required to convert the polyketide backbone into the biologically active calcimycin. Using targeted mutagenesis of Streptomyces we were able to show that calM from the calcimycin biosynthesis gene cluster is required for calcimycin production. Inactivating calM by PCR targeting, caused high level accumulation of N-demethyl calcimycin. CalM in the presence of S-adenosyl-L-methionine converted N-demethyl calcimycin to calcimycin in vitro. The enzyme was determined to have a kinetic parameter of Km 276 μM, kcat 1.26 min−1 and kcat/Km 76.2 M−1 s−1. These results proved that CalM is a N-methyltransferase that is required for calcimycin biosynthesis, and they set the stage for generating much desired novel calcimycin derivatives by rational genetic and chemical engineering. 相似文献
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