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排序方式: 共有448条查询结果,搜索用时 15 毫秒
91.
E. A. Kravets Yu. V. Sidorchuk I. I. Horyunova S. H. Plohovskaya S. R. Mursalimov E. V. Deineko A. I. Yemets Ya. B. Blume 《Cytology and Genetics》2016,50(5):267-277
Comparative cytological analysis of intra- and intertissular cytomictic interactions in the microsporogenesis of mono- and dicotyledonous plants has been performed for two cellular systems: the microsporocytes and the tapetum. Cytomixis was shown to be more common for intratissular interactions, and cytomixis in the tapetum exhibited taxon-specific features, both structural and temporal. Nuclear migration in the microsporocytes mostly occurred during the zygotene–pachytene and exhibited certain synchrony with cytomixis in the tapetum. Intertissular cytomictic interactions (between the tapetum and the microsporocytes) were detected only in monocotyledonous plant anthers. Intertissular interactions may reflect more intense competition for space between the tapetum and the microsporocytes during the differentiation of anther tissues. The polyploid nuclei of the tapetum and the syncytia are powerful acceptors that can compete with the microsporocytes and attract the chromatin during translocation of the latter. The absence of intertissular interactions in dicotyledonous plants may be indicative of a better balance between the processes of differentiation of somatic and generative tissues of the microsporangium as compared to monocotyledonous plants. 相似文献
92.
Announcement—guidance document for acquiring reliable data in ecological restoration projects
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Martin A. Stapanian Karen Rodriguez Timothy E. Lewis Louis Blume Craig J. Palmer Lynn Walters Judith Schofield Molly M. Amos Adam Bucher 《Restoration Ecology》2016,24(5):570-572
The Laurentian Great Lakes are undergoing intensive ecological restoration in Canada and the United States. In the United States, an interagency committee was formed to facilitate implementation of quality practices for federally funded restoration projects in the Great Lakes basin. The Committee's responsibilities include developing a guidance document that will provide a common approach to the application of quality assurance and quality control (QA/QC) practices for restoration projects. The document will serve as a “how‐to” guide for ensuring data quality during each aspect of ecological restoration projects. In addition, the document will provide suggestions on linking QA/QC data with the routine project data and hints on creating detailed supporting documentation. Finally, the document will advocate integrating all components of the project, including QA/QC applications, into an overarching decision‐support framework. The guidance document is expected to be released by the U.S. EPA Great Lakes National Program Office in 2017. 相似文献
93.
The 18S ribosomal RNAs of 21 tetrapods were sequenced and aligned with five
published tetrapod sequences. When the coelacanth was used as an outgroup,
Lissamphibia (living amphibians) and Amniota (amniotes) were found to be
statistically significant monophyletic groups. Although little resolution
was obtained among the lissamphibian taxa, the amniote sequences support a
sister-group relationship between birds and mammals. Portions of the 28S
ribosomal RNA (rRNA) molecule in 11 tetrapods also were sequenced, although
the phylogenetic results were inconclusive. In contrast to previous
studies, deletion or down- weighting of base-paired sites were found to
have little effect on phylogenetic relationships. Molecular evidence for
amniote relationships is reviewed, showing that three genes
(beta-hemoglobin, myoglobin, and 18S rRNA) unambiguously support a
bird-mammal relationship, compared with one gene (histone H2B) that favors
a bird- crocodilian clade. Separate analyses of four other genes (alpha-
crystallin A, alpha-hemoglobin, insulin, and 28S rRNA) and a combined
analysis of all sequence data are inconclusive, in that different groups
are defined in different analyses and none are strongly supported. It is
suggested that until sequences become available from a broader array of
taxa, the molecular evidence is best evaluated at the level of individual
genes, with emphasis placed on those studies with the greatest number of
taxa and sites. When this is done, a bird-mammal relationship is most
strongly supported. When regarded in combination with the morphological
evidence for this association, it must be considered at least as plausible
as a bird-crocodilian relationship.
相似文献
94.
Wolfram Bode Hans -Jürgen Hinz Rainer Jaenicke Alfred Blume 《European biophysics journal : EBJ》1974,1(1):55-64
The heat effects accompanying the isothermalin vitro polymerization ofPr. mirabilis flagellin on short flagella fragments (seeds) have been measured in phosphate buffer pH 7, at various temperatures employing a batch microcalorimeter. Additionally, at 20 ?C, measurements have been performed in phosphate as well as Tris- HCl buffer at pH 7.5. The rate of both heat uptake and release during the process of polymerization was shown to be proportional to the rate of molar ellipticity changes observed by parallel circular dichroism experiments. No change in the state of protonation of flagellin occurs during the polymerization as indicated by the constancy of the enthalpy values determined in buffers with different heats of ionization. The apparent molar enthalpy of polymerization at 25 ?C, pH 7, is ?34.7±3 kcal per mole of flagellin, the relatively large error mainly resulting from uncertainties of the determination of the percentage of unpolymerized monomers after completion of the reaction. The most prominent feature of the results obtained in this study is the large temperature variation of the enthalpy, corresponding to a temperature independent heat capacity change ofδc p =?3039±100 cal per degree per mole of flagellin, the error limits referring to the standard deviation in a linear regression analysis. 相似文献
95.
Zusammenfassung Es werden Befunde aus einer Sippe mit PGI-Defizienz mitgeteilt. Die beiden Patienten haben eine nichtsphärocytäre hämolytische Anämie, sie besitzen den homozygoten Phänotypus PGI9. Die Eltern sind heterozygot PGI 9-1. Der Zymogrammvergleich von Eltern und Kindern spricht für die Hypothese, daß die PGI ein dimeres Molekül sei, das normalerweise aus identischen Polypeptidketten aufgebaut ist.
Mit Unterstützung durch die Deutsche Forschungsgemeinschaft. 相似文献
Formal genetics of phosphoglucoseisomerase investigations of a family with PGI-Deficiency
Summary In a family two children exhibited a non-sphaerocytic hemolytic anemia; they revealed the homozygous phenotype PGI9. The parents are heterozygous PGI 9-1. The comparison of the zymogram pattern of both parents and children allows the conclusion that the PGI molecule is a dimer which has identical subunits in homozygous individuals.
Mit Unterstützung durch die Deutsche Forschungsgemeinschaft. 相似文献
96.
Developmental Effects of Sandoz 6706 on Activities of Enzymes of Phenolic and General Metabolism in Barley Shoots Grown in the Dark or under Low or High Intensity Light 总被引:6,自引:5,他引:1
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The activities of three enzymes of phenolic biosynthesis and six of general metabolism were studied at 24-hour intervals between the 3rd and 8th day after planting in barley shoots treated with the chlorosis-inducing herbicide Sandoz 6706 and grown in the dark or under high or low intensity light. The herbicide had no effect on fresh weight or soluble protein (per shoot) in plants grown in the dark or under low intensity light, but slightly decreased these parameters in plants grown for more than 5 days under high intensity light. In dark-grown seedlings the herbicide had no detectable effects on plastid ultrastructure or on the activity of malate dehydrogenase, cytochrome c oxidase, NADP-cytochrome c reductase, triose phosphate isomerase, peroxidase, catalase, shikimate dehydrogenase, phenylalanine ammonia-lyase, or chalcone-flavanone isomerase. Under low intensity light, Sandoz 6706-treated plants developed plastids with single thylakoids extending across the organelle, and the activity of all enzymes examined was increased to varying degrees. When the herbicide-treated plants were grown under high intensity light, plastid lamellar organization was severely disrupted. Activities of shikimate dehydrogenase and chalcone-flavanone isomerase were markedly enhanced, phenylalanine ammonia-lyase activity slightly promoted, and catalase activity severely inhibited. The other enzymes were not appreciably affected by Sandoz 6706 under high intensity light. It is concluded that the changes in plastid ultrastructure and enzyme activities of the herbicide-treated plants are largely secondary photomorphogenetic or photooxidative responses in the carotenoid-free plants in which chlorophylls accumulate in reduced amounts (low intensity light) or are completely absent (high intensity light). 相似文献
97.
Zusammenfassung Wir berichten über formalgenetische Untersuchungen zur Glutathionreduktase menschlicher Erythrocyten. Durch Aktivitätsbestimmung des Enzyms in den Erythrocyten, durch Enzymelektrophorese und durch den Heinzkörpertest lassen sich heterozygote Merkmalsträger des Glutathionreduktasemangels von gesunden Normalpersonen unterscheiden. Wahrscheinlich liegen qualitativ und quantitativ veränderte Enzymproteine vor (enzymkinetische Daten und elektrophoretische Eigenschaften). Wir verfügen über Beobachtungen in insgesamt neun Familien, bei denen formalgenetische Untersuchungen vorgenommen wurden. Der auf Grund früherer Untersuchungen vermutete autosomal dominante Erbgang wird bestätigt.
Mit dankenswerter Unterstützung durch die Deutsche Volkswagen-Stiftung.
Herrn Professor Dr. H. E. Bock, Tübingen, zum 65. Geburtstag gewidmet. 相似文献
Family studies on glutathione reductase from red blood cells
Summary We report on formal genetical studies of glutathione reductase from human red blood cells. Heterozygotes can he distinguished from normals by determination of glutathione reductase activity, electrophoresis of this enzyme, and Heinz-body-test. Probably the enzyme protein are qualitatively and quantitatively different (biochemical data and electrophoretic behaviour). The mode of inheritance of glutathione reductase deficiency is autosomally dominant.
Mit dankenswerter Unterstützung durch die Deutsche Volkswagen-Stiftung.
Herrn Professor Dr. H. E. Bock, Tübingen, zum 65. Geburtstag gewidmet. 相似文献
98.
Summary The frequency of heterozygotes for the glutathione-reductase in a sample of 215 young healthy Germans is 1,9%. Suggesting a 2-allele-model we can calculate the frequency of the three phenotypes in the population: GR(A)=98,1%, GR(AB)=1,9%, GR(B)=0,009%. No correlation between blood-and serum-groups and the enzyme activity could be found.
Direktor: Prof. Dr. med. G. W. Löhr
Direktor: Prof. Dr. med. G. G. Wendt
Mit dankenswerter Unterstützung durch die Deutsche Volkswagen-Stiftung. Herrn Professor Dr. H. E. Bock, Tübingen, zum 65. Geburtstag gewidmet. Wesentliche Teile dieser Arbeit werden von Andreas v. Lingen der Medizinischen Fakultät Marburg als Dissertation vorgelegt. 相似文献
Direktor: Prof. Dr. med. G. W. Löhr
Direktor: Prof. Dr. med. G. G. Wendt
Mit dankenswerter Unterstützung durch die Deutsche Volkswagen-Stiftung. Herrn Professor Dr. H. E. Bock, Tübingen, zum 65. Geburtstag gewidmet. Wesentliche Teile dieser Arbeit werden von Andreas v. Lingen der Medizinischen Fakultät Marburg als Dissertation vorgelegt. 相似文献
99.
M Henke L M Yonemoto G S Lazar L Gaidulis T Hecht S Santos K G Blume 《The journal of histochemistry and cytochemistry》1984,32(7):712-716
A visual test for detection of granulocyte surface markers using the avidin-biotin complex (ABC) has been developed. That this assay is highly specific, reproducible, and sensitive was determined by studying the expression of HLA antigens on granulocytes with monoclonal antibodies. Further, using granulocyte specific alloantisera, the results of the ABC test compared well to data from leukoagglutination assays and indirect immunofluorescence tests. The assay is particularly advantageous in that granulocytes can be stored, only small amounts of cells and sera are needed, and heterogeneous cell populations can easily be studied. 相似文献
100.
The role of lipids in maintaining ligand binding properties of affinity-purified bovine striatal dopamine D2 receptor was investigated in detail. The receptor, purified on a haloperidol-linked Sepharose CL6B affinity column, exhibited low [3H]spiroperidol binding unless reconstituted with soybean phospholipids. In order to understand the role of individual phospholipids in maintaining the receptor binding activity, the purified preparation was reconstituted separately with individual phospholipids and assayed for [3H]spiroperidol binding. Except for phosphatidylcholine and phosphatidylethanolamine, that respectively restored 30 and 20% binding as compared to that obtained with soybean lipids, reconstitution with other lipids had very little effect. When various combinations of phospholipids were used for reconstitution, a phosphatidylcholine and phosphatidylserine mixture seemed to almost fully restore the receptor binding. A mixture of phosphatidylcholine and phosphatidylethanolamine was as effective as phosphatidylcholine alone in reconstituting ligand binding; however, when phosphatidylserine was also included in the mixture, there was a pronounced increase in binding (about 2-fold compared to the soybean lipids and about 6-fold compared to the phosphatidylcholine-phosphatidylethanolamine mixture). Substitution of other phospholipids or cholesterol for phosphatidylserine in phosphatidylcholine and phosphatidylethanolamine mixture had little effect. Maximal reconstitution of [3H]spiroperidol binding was obtained with phosphatidylcholine, phosphatidylethanolamine and phosphatidylserine mixture (2:2:1, w/w) at a concentration of 0.5 mg/ml. The reconstituted receptor exhibited high affinity binding for [3H]spiroperidol which was comparable to that obtained with membrane or solubilized preparations. Various dopaminergic antagonists and agonists showed appropriate order of potency for the reconstituted receptor. The presently described reconstitution data suggest a role of specific phospholipids in preserving the binding properties of dopamine D2 receptor and should prove useful in studies on functional reconstitution of the receptor. 相似文献