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排序方式: 共有2394条查询结果,搜索用时 15 毫秒
1.
Iteng Ng-Choi ngel Oliveras Lidia Feliu Marta Planas 《International journal of peptide research and therapeutics》2020,26(2):695-707
The feasibility of the solid-phase intramolecular 4(5)-arylation of a histidine residue to obtain biaryl cyclic peptides bearing a His-Phe linkage was esta 相似文献
2.
Mercedes González-Wangüemert Francisca Giménez-Casalduero Ángel Pérez-Ruzafa 《Biochemical Systematics and Ecology》2006
Genetic variation at 10 enzyme loci was analysed in Elysia timida sacoglossan mollusc samples, originating from both coastal lagoon and marine sites. The observed heterozygosity ranged from 0.390 (Los Urrutias) to 0.277 (Tabarca). Marine and coastal lagoon populations were characterised by exclusive alleles. 相似文献
3.
I Monta?és A Badía M A Réngel J M López-Novoa 《Proceedings of the Society for Experimental Biology and Medicine. Society for Experimental Biology and Medicine (New York, N.Y.)》1992,199(3):321-326
Renal metabolism has been studied in eight dogs before and 48 hr after a 60-min period of renal ischemia induced by clamping the left renal artery with the simultaneous removal of the right kidney, and in 12 sham-operated animals. The study involved the measurement of renal uptake and production of lactate, glutamine, glutamate, alanine, ammonium, and oxygen, and the measurement of the tissue concentrations of ATP, glutamine, lactate, alpha-ketoglutarate, aspartate, and alanine in the renal cortex. Two days after a temporary renal ischemia, the remaining kidney showed a 22% decrease in glomerular filtration rate (GFR) and a 25% decrease in renal plasma flow. Fractional sodium and potassium excretions were similar to those of control dogs. Renal production or extraction of glutamine, glutamate, alanine, ammonium, and oxygen (all expressed by 100 ml of GFR) was not significantly different in basal conditions or 2 days after ischemia, but lactate extraction was reduced in postischemic kidneys (-101 +/- 29 vs -204 +/- 38 mumol/100 ml GFR in control dogs). The cortical concentrations of glutamine and glutamate were lower in postischemic than in control kidneys. No differences were found in cortical concentration of alpha-ketoglutarate, aspartate, lactate, pyruvate, or ATP, but total nucleotides and inorganic phosphate were decreased in postischemic kidneys. It is concluded that in the recovery phase of the ischemia, a decreased lactate uptake is the main metabolic change, and total ATP production is adapted to the decrease of GFR and sodium reabsorption. 相似文献
4.
5.
Size variation in Brachionus plicatilis resting eggs 总被引:1,自引:0,他引:1
The effect of temperature and salinity on resting egg size of two Brachionus plicatilis (Rotifers) clones was investigated. Clones were selected according to their different behaviour in laying resting eggs: one clone ejects them, whereas they remain inside the females body in the other clone. The difference in resting eggs size between the two clones is noticeable, although the difference is not as great as that between female body size. An important temperature-salinity interaction on resting egg size has been observed. The general inverse relationship between size and temperature is only true at lower temperatures. At high temperatures size varies around the mean although could be greater than at intermediate temperatures. This is more evident at the intermediate salinity tested which is considered to be the closest to the optimum in our experiments. This pattern of variation suggests that mean size is bigger than expected, in relation to temperature and salinity, when these factors have values close to the extremes of their range, normally found in nature, and to which adaptative mechanisms can evolve. Size is bigger at the salinity — temperature low - low and high - high combinations which are the most commonly found in the temperate environments. 相似文献
6.
Aurelio Serrano Patricia Giménez Siegfried Scherer Peter Böger 《Archives of microbiology》1990,153(6):614-618
The in situ location of the electron carrier protein cytochrome C
553 (cyt c
553) has been investigated in both vegetative cells and heterocysts of the cyanobacterium Anabaena variabilis ATCC 29413 using the antibody-gold technique, carried out as a post-ernbedding immunoelectron microscopy procedure. When using a rabbit polyclonal anti-cyt c
553 specific antiserum an intense labelling, associated mainly with the cell periphery (cytoplasmic membrane and periplasmic area), was seen in both heterocysts and vegetative cells. The selective release of most of the cellular cyt c
553 during a Tris-EDTA treatment confirms a periplasmic localization of this protein in A. variabilis. The results indicate that most of cyt c
553 is located in the periplasmic space. The roles ascribed to this protein in both respiration and photosynthesis in cyanobacteria are discussed.Abbreviations Cyt c
553
cytochrome c
553
- PBS
phosphate buffered saline (20 mM sodium phosphate, 0.9% NaCl, pH 7.4)
- PMSF
phenylmethylsulfonyl fluoride
Recipient of a Research Fellowship of the Alexander von Humboldt Foundation (Bonn, FRG) for a leave to the University of Konstanz. 相似文献
7.
Characterization of a DNA binding protein of bacteriophage PRD1 involved in DNA replication. 总被引:5,自引:2,他引:3
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T M Pakula J Caldentey M Serrano C Gutierrez J M Hermoso M Salas D H Bamford 《Nucleic acids research》1990,18(22):6553-6557
Escherichia coli phage PRD1 protein P12, involved in PRD1 DNA replication in vivo, has been highly purified from E. coli cells harbouring a gene XII-containing plasmid. Protein P12 binds to single-stranded DNA as shown by gel retardation assays and nuclease protection experiments. Binding of protein P12 to single-stranded DNA increases about 14% the contour length of the DNA as revealed by electron microscopy. Binding to single-stranded DNA seems to be cooperative, and it is not sequence specific. Protein P12 also binds to double-stranded DNA although with an affinity 10 times lower than to single-stranded DNA. Using the in vitro phage phi 29 DNA replication system, it is shown that protein P12 stimulates the overall phi 29 DNA replication. 相似文献
8.
A novel and conserved salt-induced protein is an important determinant of salt tolerance in yeast. 总被引:32,自引:3,他引:29
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![点击此处可从《The EMBO journal》网站下载免费的PDF全文](/ch/ext_images/free.gif)
We have isolated a novel yeast gene, HAL1, which upon overexpression improves growth under salt stress. In addition, disruption of this gene decreases salt tolerance. Therefore HAL1 constitutes a rate-limiting determinant for halotolerance. It encodes a polar protein of 32 kDa located in the yeast cytoplasm and unrelated to sequences in data banks. The expression of this gene is increased by high concentrations of either NaCl, KCl or sorbitol. On the other hand, the growth advantage obtained by overexpression of HAL1 is specific for NaCl stress. In cells overexpressing HAL1, sodium toxicity seems to be counteracted by an increased accumulation of potassium. The HAL1 protein could interact with the transport systems which determine intracellular K+ homeostasis. The HAL1 gene and encoded protein are conserved in plants, being induced in these organisms by salt stress and abscisic acid. These results suggest that yeast serves as a convenient model system for the molecular biology of plant salt tolerance. 相似文献
9.
10.
Francisco J. Acosta Jose M. Serrano Jesus M. Barandica Francisco Lopez 《Journal of Insect Behavior》1992,5(3):337-346
The focal-animal technique assumes the continuous recording of the behavior of an individual during a certain time interval. The length of this interval (sampling unit) can be problematic when estimating the duration of behavioral acts. Two acts from the behavioral repertoire of the ant Leptothorax fuenteiwere focused on in this work at different ranges of temporal scales. Analyzing these acts we show the possibility of existence of a sampling artifact, in such a way that the estimates of the durations of the acts would be forced to depend upon the length of the sampling unit that is being used. 相似文献