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21.
Polypeptide composition of rat sperm outer dense fibers. A simple procedure to isolate the fibrillar complex 总被引:6,自引:0,他引:6
Treatment of caput or cauda epididymal rat sperm with a low concentration (0.05%) of the cationic detergent cetyltrimethylammonium bromide and 30 mM 2-mercaptoethanol solubilized most of the sperm structures except for the sperm head and the outer dense fiber-connecting piece complex. The latter were purified, and about 10% of these complexes are formed by nine fibers attached to the connecting piece. Of these fibers, two are shorter than the other seven and presumably correspond to fibers 3 and 8 (Fawcett, D.W. (1975) Dev. Biol. 44, 394-436). Electron microscopy confirmed the purity of the isolated outer dense fibers and revealed their characteristic irregular cross-sectional shape. Polyacrylamide gel electrophoresis in the presence of sodium dodecyl sulfate showed six major polypeptides (Mr = 87,000, 30,400, 26,000, 18,400, 13,000, and 11,500) with a high content of serine, aspartic and glutamic acids, proline, cysteine, leucine, and tyrosine. Furthermore, several lines of evidence indicate a close structural relationship between the components of 30,400 and 26,000 Da. The six major components of the fibers are phosphorylated at serine residues. These results indicate that the major components of rat sperm outer dense fibers are a unique family of phosphoproteins. 相似文献
22.
Sven Fischer Axel Vischer Vera Preac-Mursic Peter C. Weber 《Prostaglandins & other lipid mediators》1987,34(3)
In a 24 h kinetic study docosahexaenoic acid (DCHA, C22:6n-3) or eicosapentaenoic acid (EPA, C20:5n-3) were given in a single dose to healthy male volunteers. PGI3-M, the main urinary metabolite of prostaglandin I3 was below the detection limit in the control periods, but was excreted already in the first 4 h after ingestion of DCHA or EPA and decreased thereafter. Excretion of PGI2-M did not change significantly. In a second dietary trial DCHA and EPA were given cross-over to 7 healthy male volunteers for 6 days. PGI3-M was formed after DCHA and EPA in amounts of 35 and 20 % of PGI2-M and showed a considerable interindividual variation. The structure of PGI3-M was verified by independant biochemical synthesis. Our data indicate that dietary DCHA is retroconverted to EPA in man, which is quickly transformed - like dietary EPA itself - to prostaglandin I3. DCHA may therefore serve as a precursor fatty acid for EPA and its cyclooxygenated and lipoxygenated products. 相似文献
23.
Violeta Datcheva Aleksei Kamernitskii Radoslav Vlahov Natalia Voishvillo Vera Levi Irina Reshetova Elena Chernoburova 《Applied microbiology and biotechnology》1986,25(1):14-17
Summary A high-yield microbiological transformation of polyfunctional 5-3-acetoxy steroids, containing an additional ring E, by Corynebacterium mediolanum strain B-964 was carried out, resulting in the corresponding 4-3-ketones. It was shown that the type of transformation and the yield of the reaction depend on the degree of saturation of the ring E and on the position of the oxygen-containing substituents in it. 相似文献
24.
Cucurbitaceae are characterized by a high copy number for nuclear ribosomal RNA genes. We have investigated the genomic ribosomal DNA (rDNA) of four closely related species of this family with respect to structure, length heterogeneity, and evolution. InCucumis melo (melon) there are two main length variants of rDNA repeats with 10.7 and 10.55kb.Cucumis sativus (cucumber) shows at least three repeat types with 11.5, 10.5, and 10.2kb.Cucurbita pepo (zucchini) has two different repeat types with 10.0 and 9.3kb. There are also two different repeat types inCucurbita maxima (pumpkin) of about 11.2 and 10.5kb. Restriction enzyme mapping of the genomic rDNA of these four plants and of cloned repeats ofC. sativus shows further heterogeneities which are due to methylation or point mutations. By comparison of the restriction enzyme maps it was possible to trace some evolutionary events in the family ofCucurbitaceae. Some aspects of regulation and function of the middle repetitive rRNA genes (here between 2000 and 10000 copies) are discussed. 相似文献
25.
Vera Hadačová Květa Vacková Eva Klozová M. Kutáček Květa Pitterová 《Biologia Plantarum》1983,25(3):209-215
In partly purified protein complexes obtained from 22 species of theAllium genus and 6 cultivars ofAllium cepa the activity of cholinesterases was detected and measured using the method of Ellman et al. The degree of its inhibition with 10-4 M neostigmine was also tested. It was found that the activity of cholinesterase differed in individual species up to two hundred times, while the differences in the inhibitory activity of 10-4 M neostigmine occurred only in a few cases. Individual sections and cultivars could not be characterized on the basis of the differences in the activities of the cholinesterases. Of all the sections that ofPhyllodolon shows the highest average activity. In the case of the tested cultivars distinctly the lowest activity was observed in cv. Kastická. The values of the enzymatic activity measured by Ellman’s method in this plant material include the activity of specific and unspecific cholinesterases and the part uninhibitable by neostigmine. 相似文献
26.
Malate dehydrogenase isoenzymes were studied in tenAllium species and in six cultivars ofA. cepa by isoelectric focusing in polyacrylamide gel with Ampholine pH 3.5–10.0. Using this method better resolution was obtained than by polyacrylamide gel electrophoresis. The number of MDH isoenzymes obtained by isoelectric focusing is from five to ten in the range of pH 3.65 to 6.75. MDH isoenzymes can be used for characterization on the level of species and cultivars (inA. cepa), but its use on the level of sections and subgenera is questionable. 相似文献
27.
Cristina Rinaldi-Garaci Enrico Garaci Vera Del Gobbo Cartesio Favalli Teresa Jezzi Allan L. Goldstein 《Cellular immunology》1983,80(1):57-65
The effects of thymosin-α1 on the stimulation of specific release of prostaglandin E2 (PGE2) from splenic lymphocytes and thymocytes were studied. Experiments were also performed to study in parallel the absolute levels of thymosin-α1 in the blood and the induction of serum FTS activity and of azathioprine sensitivity of spleen cells from adult thymectomized (ATx) mice. A significant difference in the release of PGE2 between normal splenocytes and splenocytes from ATx mice was observed. Thymosin-α1 at certain concentrations was able to stimulate PGE2 release from lymphocytes of ATx mice while inhibiting release in lymphocytes of normal mice. Also, thymocytes were stimulated to release PGE2 after incubation with α1 in a manner similar to that seen in spleen cells of ATx mice. Approximately the same concentration of α1 was found to also correct the low azathioprine sensitivity of splenocytes from ATx mice. Determinations of FTS-like activity in the blood and the pharmacokinetics of α1 after administration of this synthetic molecule show a clear dissociation. A maximum peak of α1 activity was obtained after 1 hr, while maximal FTS-like activity was observed after 24 hr. The inhibition of the induction by α1 of FTS-like activity and of Thy 1.2 antigen by indomethacin suggests that the action of α1 requires prostaglandin biosynthesis. 相似文献
28.
29.
A new dissimilarity measure, Uppsala dissimilarity, is proposed. It is a Manhattan-type measure in between the Canberra and Gower measures, based on the differences between scores in relevés compared, but it also takes both the sums of scores and the difference between maximum and minimum score into account. The measure is considered realistic for phytosociological material.A new optimality criterion has been developed after unsatisfactory results had been obtained with the DOL criterion (Popma et al. 1983) which was developed previously by our group. Problems with DOL were especially met when the criterion was applied to the distribution of only one species over the cluster array obtained. The new criterion takes both internal cluster homogeneity and between-cluster dissimilarity into account. Between-cluster dissimilarity is calculated for all other clusters and not only for the nearest neighbour, as in DOL. The new criterion has both an unweighted form: SOM, and a form with weighting for cluster size: SWOM.This new criterion was successfully applied to the evaluation of the sharpness of distribution of individual species over cluster arrays, under the name of SIM: species indication measure and SWIM, species weighted indication measure.The measures were applied to some test data. Differences between the unweighted and weighted forms were found which could not be easily interpreted.Some remarks are made on the coherence of d-SAHN and h-SAHN approaches in agglomerative clustering within the new strategy proposed.Abbreviations DOL =
Detection of Optimal Level
- S(W)IM =
Species (Weighted) Indication Measure
- S(W)OM =
Standardized (Weighted) Optimality Measure
- UD =
Uppsala Dissimilarity measure
- WPGMA =
Weighted Pair-Group Method Average linking clustering
- SAHN =
Sequential Agglomerative Hierarchical Non-overlapping clustering 相似文献
30.
Chilling ofArabidopsis thaliana (L.) Heynh. callus tissue to 4 °C led to conditions of oxidative stress, as indicated by increased levels of the products of peroxidative damage to cell membranes. Cellular H2O2 was also observed to increase initially upon chilling but by day 8 cellular levels had declined to below control levels. Although levels of catalase activity remained similar to those in unchilled tissue, activity of ascorbate peroxidase increased between days 4 and 8 of chilling to 4 °C. In callus held at 23 °C, levels of reduced glutathione remained static whereas they rose in callus held at 4 °C. Levels of oxidised glutathione were initially low but increased significantly by day 4 in the chilled callus. At 23 °C, however, levels of oxidised glutathione remained low. Between days 1 and 3 at 4 °C, levels of glutathione reductase activity increased but by day 8 glutathione reductase activity was similar to that in cells held at 23 °C. Exposure of callus to abscisic acid at 23 °C also led to increased activities of ascorbate peroxidase and glutathione reductase.Abbreviations ABA
abscisic acid
- GSH
reduced glutathione
- GSSG
oxidised glutathione
- TTC
2,35-triphenyltetrazolium chloride
This work is supported by a grant from the Biotechnology and Biological Sciences Research Council. 相似文献