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41.
Michael R. Boarder Alexandre J. Lockfeld Jack D. Barchas 《Journal of neurochemistry》1982,38(2):299-304
Abstract: A specific and sensitive radioimmunoassay procedure for Metenkephalin[Arg6 ,Phe7 ] which allows its measurement in regions of the rat brain is described. The antiserum was raised against the methionine sulphoxide derivative of the peptide, and all samples and standards were oxidized with hydrogen peroxide prior to use in the assay with chloramine T-oxidized 125 I-labelled Met(O)-enkephalin[Arg6 ,Phe7 ]. The only significant cross-reactivity was 30% with the reduced heptapeptide Met-enkephalin[Arg6 ,Phe7 ]. The assay showed less than 0.15% cross-reactivity with fragments of the heptapeptide and with leucine-enkephalin-containing peptides. Acid acetone extraction of rat striatum followed by Sephadex G-50 chromatography and reverse-phase high pressure liquid chromatography showed that essentially all immunoreactivity co-chromatographed with Met-enkephalin[Arg6 ,Phe7 ]. This confirmed the specificity of the assay and showed that the striatum does not contain a high concentration of larger molecular weight forms with the heptapeptide at the COOH terminus. Distribution of the heptapeptide followed that of methionine enkephalin, with highest concentrations in the globus pallidus, intermediate levels in caudate-putamen and hypothalamus, and low levels in cortex and cerebellum. 相似文献
42.
Thermal Denaturation of Native Striatal Tyrosine Hydroxylase: Increased Thermolability of the Phosphorylated Form of the Enzyme 总被引:5,自引:5,他引:0
Mitchell A. Lazar Roger J. W. Truscott Joachim D. Raese Jack D. Barchas 《Journal of neurochemistry》1981,36(2):677-682
Tyrosine hydroxylase was purified from bovine corpus striatum. The native enzyme had a half-life of 15 +/- 3 min at 50 degrees C. Phosphorylation of tyrosine hydroxylase with protein kinase purified from both corpus striatum and heart activated the enzyme, but activity was rapidly lost with additional preincubation of the enzyme at 30 degrees C. Thermal denaturation studies indicated that phosphorylated tyrosine hydroxylase had a half-life of 5 +/- 2 min at 50 degrees C 相似文献
43.
44.
Michael P. Roberts Jack C. Vaughn 《Biochimica et Biophysica Acta (BBA) - Gene Structure and Expression》1982,697(2):148-155
The haploid genome size of Artemia is determined to be about 0.9·1012, as evidenced both by Feulgen microspectrophotometry of individual diploid class nuclei, which are but one of five polyploid classes present within the larvae, and by analysis of the reassociation kinetics of the isolated single copy DNA component. Polysomes isolated from 24-h incubation stage larvae contain an average of 10 ribosomes per messenger RNA molecule. Their rRNAs are found to have sedimentation coefficients of 18 S and 26 S, corresponding to molecular weights of 0.70·106 and 1.40·106, respectively, as determined by polyacrylamide electrophoresis and also by sucrose density centrifugation. Denaturation in glyoxal followed by agarose gel electrophoresis shows that unlike deuterostome rRNAs, Artemia 26 S rRNA contains a cryptic nick about midway in the molecule, which is not found in the 18 S molecule. Isolated rRNAs were labelled in vitro with 125I and hybridized with filter-immobilized DNA to saturation, which occurred at 0.051% for Xenopus, and at 0.074% for Artemia. From these results, it is calculated that in the haploid Artemia genome there are about 320 copies of the (18 S + 26 S) ribosomal RNA genes. Reciprocal heterologous hybridizations between these two species show that they share about 30% homology between their rDNA coding sequences. 相似文献
45.
An ecological study of the rotifer species Trochosphaera solstitialis (Thorpe, 1893) was conducted for a period of eight months in a temporary pond in eastern Texas, U.S.A. The pond was found to be environmentally stressed and contained large amounts of decomposing vegetation. Physico-chemical factors contributing to the stressed conditions were low dissolved oxygen concentrations, low pH values, high ammonia concentrations, and high color values caused by large concentrations of iron, tannin and lignin. Large concentrations of iron, tannin, and lignin seem to be highly correlated with T. solstitialis populations. Physicochemical conditions probably eliminated predators of the rotifer, such as fish. Males of T. solstitialis were observed which never left the body cavity of the female. Males probably do not feed with an apparent rudimentary digestive system. 相似文献
46.
The effect of the transition metal compound trans-[Rh(4-ethylpyridine)4Cl2]Cl x 2H2O on the syntheses of DNA, RNA, and protein has been investigated for an auxotrophic bacterial strain, Escherichia coli JS-1, incapable of thymidine, uridine, and histidine syntheses. At low concentration (7.4 x 10(-6) M), this rhodium complex interferes with normal cell division and induces the formation of filaments comparable to those observed in the presence of the cis-(NH3)2PtClx antitumour agents. Once the suppressed growth rate of the filamenting cells has been taken into account, the rhodium compound is found not to alter macromolecular synthesis. Again this is consistent with similar observations made for the platinum compounds. 相似文献
47.
Wilfried W. de Jong Louis H. Cohen Jack A.M. Leunissen Anneke Zweers 《Biochemical and biophysical research communications》1980,96(2):648-655
αAIns, an elongated α-crystallin A chain previously observed in rat, was present beside the normal αA chain in mouse, gerbil and hamster, which places its origin at least 30 million years ago. Like in rat the sequences of golden hamster αAIns and αA were found to be identical, apart from the internal insertion of 22 residues in αAIns. The hamster chains only differed from the rat chains by a single substitution in the inserted sequence of αAIns. The origin of αAIns, by insertion of 22 residues in an otherwise unchanged αA chain, and its rigid evolutionary conservation are most easily explained by assuming the incomplete removal of a putative intervening sequence from the precursor mRNA of αA, leaving an intracistronic insert of 66 nucleotides in part of the eventually translated mRNA. 相似文献
48.
Summary Previous use of hemolysis time measurement to determine permeability coefficients for the red blood cell membrane rested on the assumption that cells swelling in a hypotonic medium hemolyzed immediately on reaching critical volume. By preswelling red cells to various volumes prior to immersion in hemolytic solutions we extrapolate to the hemolysis time of red cells immersed at critical volume and thereby find a significant period of time during which the cells apparently remain in a spherical form prior to release of hemoglobin. Revised estimates of permeability coefficients follow from including this spherical (nonswelling) phase. In addition, the appreciation of a characteristic time period during which the membrane is under tension provides new opportunity to study physical and chemical properties of the membrane.Presented in part at the 1974 joint meeting of the Biophysical Society and the American Society of Biological Chemists. 相似文献
49.
SpecificityH-2.7 is expressed predominantly on erythrocytes and controlled by a gene that maps within theH-2 gene complex at a locus, designated asH-2G, which apparently lies between regionsS andD. Three phenotypes have been observed with respect to this antigen: a) positive by direct test and absorption (haplotypesH-2
f
,H-2
j
,H-2
p
,H-2
s
); b) positive only by absorption (H-2
k
); and c) negative (H-2
b
,H-2
d
,H-2
q
). New crossover positions have been established for severalH-2 recombinants based on classifications for theH-2G locus. 相似文献
50.
Dr. Jack E. Brinn 《Cell and tissue research》1975,162(3):357-365
Summary The endocrine pancreas of the bullhead catfish, Ictalurus nebulosus, and the channel catfish, I. punctatas was studied by light and electron microscopy. In addition to the usual A, B and D cells, a fourth endocrine cell type was consistently observed in the electron microscope. All endocrine cell types were innervated. The vesicles of most of the nerve endings were ultrastructurally different from typical adrenergic and cholinergic vesicles, strongly suggesting the possibility of a third autonomic neurotransmitter serving as a regulator of catfish islet secretion.Supported in part by PHS grant AM 11407 awarded to Dr. Bryce Munger. 相似文献