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991.
Retinol-binding proteins in bovine interphotoreceptor matrix 总被引:5,自引:0,他引:5
992.
Martin Diatewa Yves Boulanger AndréJ.C. Stahl 《Biochemical and biophysical research communications》1982,106(2):520-525
The α and β subunits of yeast mitochondrial Phe-tRNA synthetase are separated and isolated by means of chromatography on DEAE-cellulose, after enzyme alkylation with iodoacetate. The comparison of amino acid compositions of yeast mitochondrial and cytoplasmic native Phe-tRNA synthetases and their components shows significant differences. Results indicate that the two enzymes are coded for by different nuclear genes. 相似文献
993.
Helen Kennedy 《Brittonia》1982,34(1):18-21
Calathea schunkei from San Martín Province, Peru, is described as new. This species is distinguished by the red bracts and unusual floral morphology. The petals do not reflex at anthesis, the outer staminode is lacking, and the stigma is blunt rather than the typical “scoop” shape. These unusual floral features are shared withC. timothei, a high altitude Colombian species. 相似文献
994.
A procedure for the sequential staining of metaphase cells to provide R-banding, Q-banding and C-banding of chromosomes is described. The combined techniques allow more precise identification of marker chromosomes and more accurate definition of breakpoints in the consistent chromosome translocations that are associated with certain human malignancies. 相似文献
995.
Enterobacteriaceae and Aeromonas hydrophila in Minnesota frogs and tadpoles (Rana pipiens) 总被引:1,自引:0,他引:1
D W Hird S L Diesch R G McKinnell E Gorham F B Martin C A Meadows M Gasiorowski 《Applied and environmental microbiology》1983,46(6):1423-1425
In 222 Rana pipiens frogs and 34 tadpoles captured in and near Minnesota, Aeromonas hydrophila and 29 species of Enterobacteriaceae, including yersinia enterocolitica and Salmonella arizonae, were isolated from intestines. The prevalence of members of the family Enterobacteriaceae was lowest in frogs captured in early spring and highest in frogs captured in late summer. 相似文献
996.
Fitzwater Steve E.; Knauer George A.; Martin John H. 《Journal of plankton research》1983,5(6):935-938
The effects of short-term, acute Cu exposure (6 h) on the adenylateenergy charge (ECA) of open-ocean phytoplankton populations(northeastern equatorial Pacific) were investigated. Energycharge remained at {small tilde}0.77 over the range of Cu additions(0.025 5.µg l1), even though 14C uptakeand total adenylate levels (ATP + ADP + AMP) were reduced byas much as 60%. These findings suggest that ECA alone is nota sensitive indicator of acute sublethal metal effects on phytoplankton.
1This research was supported by the NSF Biological OceanographyProgram grant #OCE 81-17286. 相似文献
997.
Hugh B. Martin L.L. Houston 《Biochimica et Biophysica Acta (BBA)/Molecular Cell Research》1983,762(1):128-134
A conjugate containing α2-macroglobulin and highly purified ricin A chain was made using N-succinimidyl-3-(2-pyridyldithio)propionate. Radioimmunoassay indicated that it contained 1.2 mol A chain per mol α2-macroglobulin. The conjugate inhibited polyuridylic-acid directed translation by rat liver ribosomes and protein synthesis in human fibroblasts. There was a 90 min lag period before the beginning of inhibition in fibroblasts, but complete inhibition could be achieved. By measuring protein synthesis as a function of protein concentration, it was demonstrated that 8.25·10?9M conjugate was required to inhibit 50% of protein synthesis in 6 h. To achieve the same level of inhibition, 165-times more (1.3·10?6M) unconjugated A chain was required, and 180-times less ricin (4.6·10?11M). Ricin was more than 28 000 times more inhibitory than A chain alone. The presence of α2-macroglobulin did not increase the cytotoxicity of unconjugated A chain, and it even protected the cells to a slight extent. The inhibitory action of the conjugate was blocked by antibodies specific for α2-macroglobulin or ricin, and it was not prevented by galactose or antibodies specific for ricin B chain. Electron microscopy of the conjugate indirectly labelled with ferritin demonstrated that it was internalized by receptor mediated endocytosis through coated pits. These data indicate that the A chain portion of the conjugate survives the conditions in the lysosomes to the extent that it retains its ability to inactivate cytoplasmic ribosomes. 相似文献
998.
Sacco C. De Vries Marco C. Harmsen Martin T. R. Kuiper Hans J. M. Dons Joseph G. H. Wessels 《Plant molecular biology》1983,2(6):295-303
Summary The molecular cloning of cDNA corresponds to pea seedling mRNA sequences encoding a shoot-specific polypeptide, the small subunit of the ribulose 1,5 biphosphate carboxylase and a component of the light-harvesting chlorophyll a/b complex is described. cDNA prepared from polysomal poly(A)RNA of light-grown shoots was enriched for shoot-specific and light-induced sequences by heterologous liquid hybridization with mercurated polysomal poly(A)RNA of dark-grown roots, followed by sulfhydryl chromatography. Cloned shoot-specific sequences were identified by 2D electrophoretic analysis of hybrid release translation products. The cloned shoot-specific sequence corresponded to a mRNA of 850 nt present both in light-and dark-grown shoots, and produced anin vitro translation product of Mr27 500 and isoelectric point of 4.7. 相似文献
999.
Nirmala SundarRaj Judith Martin Nancy Hrinya 《Biochemical and biophysical research communications》1982,106(1):48-57
Hybridomas which secrete monoclonal antibodies against human type III procollagen have been developed. By an enzyme-linked immunosorbent assay, three of the monoclonal antibodies have been determined to be against non-helical extensions of the molecules while two of the antibodies are against helical portion of the molecules which is sensitive to bacterial collagenase action. These findings have been further confirmed by carrying out immuno-reaction of the pro α-chains transferred on nitrocellulose paper from sodium dodecyl sulfate polyacrylamide gels. These monoclonal antibodies have been found to be suitable reagents for immunohistochemical studies as well as for immunoassays of type III procollagen and collagen. 相似文献
1000.
Phosphorylation of calcium adenosinetriphosphatase by inorganic phosphate: reversible inhibition at high magnesium ion concentrations 总被引:2,自引:0,他引:2
Magnesium stimulates phosphorylation of the calcium pump protein of the sarcoplasmic reticulum by inorganic phosphate, but the effect is reversed by high [Mg2+]. This reversal is readily explained in terms of the generally accepted existence of two conformational states of the enzyme, E1 and E2. E2 is the form of the enzyme that can be phosphorylated by Pi, and it has one binding site for Mg2+. E1 is the form of the enzyme that has two high-affinity Ca2+ binding sites, and it is phosphorylated by ATP when Ca2+ is bound. Mg2+ can bind weakly to the two Ca2+ sites and to a third site known to be present on E1; this stabilizes E1 at the expense of E2 when [Mg2+] is large. Stabilization of E1 at pH 6.2 and 25 degrees C was found to be a highly cooperative function of [Mg2+] and was not prevented by increasing [Pi]. The latter result requires the existence of a binding site for Pi on E1, with an affinity for Pi comparable to that of E2. Cooperativity with respect to [Mg2+] requires that E2 is the stable state of the enzyme in the absence of ligands, with an equilibrium constant [E2]/[E1] on the order of 10(3) or higher at pH 6.2 and 25 degrees C. 相似文献