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1.
Ai‐Xin Song Chen‐Jie Zhou Xiao Guan Kong‐Hung Sze Hong‐Yu Hu 《Protein science : a publication of the Protein Society》2010,19(5):1104-1109
DC‐UbP/UBTD2 is a ubiquitin (Ub) domain‐containing protein first identified from dendritic cells, and is implicated in ubiquitination pathway. The solution structure and backbone dynamics of the C‐terminal Ub‐like (UbL) domain were elucidated in our previous work. To further understand the biological function of DC‐UbP, we then solved the solution structure of the N‐terminal domain of DC‐UbP (DC‐UbP_N) and studied its Ub binding properties by NMR techniques. The results show that DC‐UbP_N holds a novel structural fold and acts as a Ub‐binding domain (UBD) but with low affinity. This implies that the DC‐UbP protein, composing of a combination of both UbL and UBD domains, might play an important role in regulating protein ubiquitination and delivery of ubiquitinated substrates in eukaryotic cells. 相似文献
2.
S A Magder G T Daughters J Hung E L Alderman N B Ingels 《European journal of applied physiology and occupational physiology》1987,56(4):467-473
The purpose of this study was to measure the changes and rates of adaptation of left ventricular volumes at the onset of exercise. Eight asymptomatic subjects, in whom intramyocardial markers had been implanted 3-6 years previously during aortocoronary bypass surgery, exercised in the supine position at a constant workload of 73.6 W for 5 min. Six also exercised first at 16.4 W, and then against a workload which progressively increased by 8.2 W every 15 s. Cardiac volumes were measured by computer assisted analysis of the motion of the implanted markers. In the constant workload test, cardiac output increased rapidly from 5.7 +/- 1 min-1 to 10.3 +/- 1.9 1 min-1 by 2 min and then increased more slowly to 10.8 +/- 2.0 1 min-1 by 5 min. The cardiac output increase was mainly due to an increase in heart rate from 68 +/- 12 beats min-1 to 120 +/- 16 beats min-1 with minimal changes in stroke volume. The time constant for the early increase in cardiac output was 45s and for heart rate, 35s. With progressively increasing workloads, there was an almost linear increase of heart rate and cardiac output, but these increased at a slower rate than during the early phase of the constant load exercise test. In conclusion: rapid changes in cardiac output during supine exercise were produced by changes in heart rate; changes in stroke volume provided minor adjustments to cardiac output; the end-diastolic volume was almost constant. 相似文献
3.
Background
Micro-biological research relies on the use of model organisms that act as representatives of their species or subspecies, these are frequently well-characterized laboratory strains. However, it has often become apparent that the model strain initially chosen does not represent important features of the species. For micro-organisms, the diversity of their genomes is such that even the best possible choice of initial strain for sequencing may not assure that the genome obtained adequately represents the species. To acquire information about a species' genome as efficiently as possible, we require a method to choose strains for analysis on the basis of how well they represent the species. 相似文献4.
The mutagenic potencies of 3 purine analogs were determined in the ad-3 forward-mutation test in growing cultures of heterokaryon 59 (H-59), a nucleotide excision repair-deficient (uvs-2/uvs-2) 2-component heterokaryon of Neurospora crassa. Two N-hydroxylaminopurines, 2-amino-6-N-hydroxylaminopurine (AHA) and 6-N-hydroxylaminopurine (HAP), were potent and strong mutagens, respectively, whereas 2-aminopurine (AP) was a moderate mutagen. Dose-response curves showed that AHA and HAP were about equally mutagenic at low doses but that AHA was more mutagenic than HAP at high doses. Comparison of these results in H-59 with our earlier results in heterokaryon 12 (H-12) of N. crassa, which is identical to H-59 except for being DNA-repair-proficient (uvs-2+/uvs-2+), shows that the defect in nucleotide excision repair due to uvs-2 has little or no effect on the mutagenic potencies of these 3 purine analogs. Therefore, the nucleotide excision-repair pathway in N. crassa that is deficient in H-59 does not appear to have a major role in the repair of pre-mutational lesions induced by these 3 purine analogs. On the other hand, based on the controls of these experiments, the frequency of spontaneous ad-3 mutants was 4 greater in H-59 than in H-12. This result suggests that the nucleotide excision-repair pathway in N. crassa that is inactivated by the uvs-2 mutation has a major role in the repair of lesions that would lead to spontaneous mutation at the ad-3+ region if they were not repaired. 相似文献
5.
Protein synthesis in the hippocampus associated with memory facilitation by corticotropin-releasing factor in rats. 总被引:2,自引:0,他引:2
The present study used pharmacological, biochemical, and behavioral methods to examine the role of protein synthesis in the hippocampus in memory processes of a passive avoidance learning in rats. Results indicated that corticotropin-releasing factor (CRF) significantly improved memory retention in rats. Both cycloheximide (CHX) and actinomycin-D (ACT-D) impaired memory at high doses. At doses of CHX and ACT-D that did not affect memory alone, they both antagonized the memory-enhancing effect of CRF. Biochemically, there were specific increases in the optical density of three protein bands in the cytosolic fraction of hippocampal cells in rats showing good memory. There were also marked increases in the optical density of two protein bands in the nucleus fraction of the same animals. Similar results were observed in animals injected with CRF. However, no significant protein alteration was observed in animals receiving stress. These results together suggest that there are new protein syntheses in the hippocampus that are specifically associated with passive avoidance learning in rats. 相似文献
6.
Scanning electron microscopy was used to study the endothelial surface of the pulmonary trunk, artery, and vein in normobaric control rats as well as in rats exposed to hypobaric hypoxia for 7 and 21 days. The individual endothelial cells of the normobaric pulmonary trunk and hilar artery were flat and slightly elongated with elevated nuclear regions, and those of the intermediate-sized artery were more elongated and had more microvilli than the large arteries studied. Their endothelial cell boundaries were outlined by beaded cytoplasmic projections. The surfaces of the normobaric hilar and intermediate-sized veins were smooth and demonstrated numerous longitudinal streaks. These venous endothelial cells were elongated and their cell boundaries were outlined by low discontinuous marginal folds. Exposure to hypobaric hypoxia caused the following changes on the arterial surface: elevation of the endothelial cells; formation of microvilli-rich cell clusters; formation of hollow defects; and the attachment of leukocytes. Hypobaric hypoxia also caused the disappearance of the longitudinal streaks and the occurrence of microvilli-rich cells in the hilar veins. The endothelial surface modifications in the hypobaric rats could be related to thickening of the endothelium, intimal edema, increased intimal connective tissue, luminal invasion of leukocytes, and increased endothelial cell proliferation, known to occur in systemic arteries of hypertensive animals. 相似文献
7.
Serge Fermandjian Constantin Sakarellos Franlois Piriou Michel Juy Flavio Toma Hung Lam Thanh Karl Lintner Mahesh C. Khosla Robert R. Smeby F. Merlin Bumpus 《Biopolymers》1983,22(1):227-231
The conformation–biological activity relationships in a series of angiotensin II analogs substituted in position 5 were studied. Results indicated that only analogs with β-branched residue in position 5 possess spectral and biological properties identical to that of parent angiotensin II. 相似文献
8.
Determination of nanogram quantities of osmium-labeled nucleic acids by stripping (inverse) voltammetry 总被引:3,自引:0,他引:3
Modification of nucleic acids with OSO4 in the presence of pyridine results in a formation of a covalently bound electroactive center in a polynucleotide chain detectable by polarographic (voltammetric) methods. It has been shown that DNA modified with osmium (DNA-Os) accumulates at the hanging mercury-drop electrode during a waiting time in a wide range of potentials between 0 and -1.0 V (against the saturated calomel electrode) and produce at neutral pH a well-developed reduction peak at about -1.2 V due to scanning in the cathodic direction. Using the differential-pulse stripping (inverse) voltammetry, nanogram quantities of single-stranded DNA-Os can be determined at relatively short waiting times (1-3 min). Double-stranded DNA is modified with osmium to a much lesser extent as compared to single-stranded polynucleotides. The degree of modification of double-helical DNA is influenced by the presence of single-stranded and distorted double-stranded regions in the DNA molecules and by the environmental conditions which influence the DNA conformation. Osmium can thus be used as a probe of the DNA structure, and a few micrograms of double-helical DNA sample suffice for the voltammetric analysis. 相似文献
9.
Hung Cao Danh Margherita Strolin Benedetti Philippe Dostert 《Journal of neurochemistry》1983,41(3):618-622
Abstract: Aldehyde dehydrogenase (ALDH) activity was measured in brains, livers, and hearts of 23–26-month-old and 3-month-old rats. A significant increase of ALDH activity was found in whole brain of old rats with both acetaldehyde (39%) and propionylaldehyde (15%) used as substrates. In different brain areas of old rats, with acetaldehyde used as substrate, a significant increase of ALDH activity was found in striatum (30–50%) and cerebral cortex (37%). However, no significant difference in ALDH activity was found in livers and hearts of young and old rats. Preliminary experiments showed a significant increase of aldehyde reductase activity (52%) with p -nitrobenzaldehyde used as substrate in whole brain of old rats compared with young rats. The present work indicates that an increase of ALDH activity in brain of old rats may be an adaptive phenomenon. 相似文献
10.