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141.
B. Rennert M. Wirth S. Günther C. Schulz 《Zeitschrift fur angewandte Ichthyologie》2005,21(5):429-432
Zander (Sander lucioperca) is one of the most important fish species in the German inland fishery. As a pelagic predator, zander is able to regulate populations of small cyprinids and perch and is therefore used in ‘top‐down’ projects to directly control the food web. At present, natural waters are mainly stocked with one‐summer‐old zander from pond hatcheries; however, such fish are poor stocking material due to low survival rates, presumably because of their small size. Two groups of 50‐day‐old zander fingerlings reared in a recirculation system (T = 23 °C) were used. For 90 days one group (FG 1) was fed with a commercial dry feed (Trouvit Pro Aqua Brut), and the other group (FG 2) was fed with chironomides (Chironomus spp.). The fat content of the dry feed was increased with fish oil supplemented up to 22%. After the rearing period the FG 1 fishes attained the largest size and fat content. A pond with a surface of 667 m2 and a mean depth of 0.8 m was stocked with 24‐tagged zander (12 of each feeding group) for wintering. After the winter period of 176 days, survival rate of each feeding group was 83.3%. The fatty acid composition in the membrane lipids of group 2 changed dramatically. In contrast to previous investigations, presented results indicate that the survival rate is not influenced by fish size (weight and length). The crucial factors for high survival rates of zander during wintering are the crude tissue fat content (>5%) and its fatty acid composition. 相似文献
142.
Foerg C Ziegler U Fernandez-Carneado J Giralt E Rennert R Beck-Sickinger AG Merkle HP 《Biochemistry》2005,44(1):72-81
Cellular entry of peptide, protein, and nucleic acid biopharmaceuticals is severely impeded by the cell membrane. Linkage or assembly of such agents and cell-penetrating peptides (CPP) with the ability to cross cellular membranes has opened a new horizon in biomedical research. Nevertheless, the uptake mechanisms of most CPP have been controversially discussed and are poorly understood. We present data on two recently developed oligocationic CPP, the sweet arrow peptide SAP, a gamma-zein-related sequence, and a branched human calcitonin derived peptide, hCT(9-32)-br, carrying a simian virus derived nuclear localization sequence in the side chain. Uptake in HeLa cells and intracellular trafficking of N-terminally carboxyfluorescein labeled peptides was studied by confocal laser scanning microscopy and flow cytometry using biochemical markers in combination with quenching and colocalization approaches. Both peptides were readily internalized by HeLa cells through interaction with the extracellular matrix followed by lipid raft-mediated endocytosis as confirmed by reduced uptake at lower temperature, in the presence of endocytosis inhibitors and through cholesterol depletion by methyl-beta-cyclodextrin, supported by colocalization with markers for clathrin-independent pathways. In contrast to the oligocationic SAP and hCT(9-32)-br, interaction with the extracellular matrix, however, was no prerequisite for the observed lipid raft-mediated uptake of the weakly cationic, unbranched hCT(9-32). Transient involvement of endosomes in intracellular trafficking of SAP and hCT(9-32)-br prior to endosomal escape of both peptides was revealed by colocalization and pulse-chase studies of the peptides with the early endosome antigen 1. The results bear potential for CPP as tools for intracellular drug delivery. 相似文献
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栲树种群的年龄结构及其生长特征 总被引:8,自引:1,他引:7
为了了解栲树的更新方式和更新动态,研究了栲树的生长特征和种群年龄结构.结果表明:栲树种群的年龄结构呈“间歇型”,经历了两个死亡高峰,并存在一个长达30年的断层;栲树的生长受光照的影响,具有很强的可塑性;由于林下光照弱且在垂直空间上不存在差异,栲树生长5~8年后进入生长的第1个抑制期,其年高生长速度可小于0.1 m,并可维持10年;栲树生长的第1个抑制期的起始时间对应着种群第1个死亡高峰期的结束时间,而其结束时间对应着种群第2个死亡高峰期的起始时间,表明栲树生长特征是影响其种群年龄结构的关键因素. 相似文献
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目的:基于钙黄绿素-铜(Ⅱ)荧光体系测定乙酰半胱氨酸。方法:在pH=8.0的Na2HPO.412H2O-KH2PO4缓冲液中,以492 nm为激发波长,520 nm为发射波长测定乙酰半胱氨酸溶液的荧光强度。结果:在pH=8.0的Na2HPO.412H2O-KH2PO4缓冲液中,二价铜离子与钙黄绿素配位引起荧光猝灭。由于乙酰半胱氨酸中巯基上的硫离子与Cu2+的亲和力很强,可从钙黄绿素-铜(Ⅱ)的络合物中夺取铜离子而使钙黄绿素游离出来,从而使体系的荧光得以恢复,并且荧光恢复的程度与加入乙酰半胱氨酸的量在一定范围内成线性。结论:建立了一种测定乙酰半胱氨酸的荧光分析新方法,该方法的线性范围为6.0 10-6~1.4 10-5 mol/L,检出限为4.010-6 mol/L。 相似文献
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Khalid A Enan Hanna Rennert Ali M El-Eragi Abdel Rahim M El Hussein Isam M Elkhidir 《Virology journal》2011,8(1):222