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21.
Pablo Rodriguez-Palenzuela Joaquin Royo Luis Gómez Rosa Sánchez-Monge Gabriel Salcedo José Luis Molina-Cano Francisco Garcia-Olmedo Pilar Carbonero 《Molecular & general genetics : MGG》1989,219(3):474-479
Summary A cDNA encoding trypsin inhibitor CMe from barley endosperm has been cloned and characterized. The longest open reading frame of the cloned cDNA codes for a typical signal peptide of 24 residues followed by a sequence which is identical to the known amino acid sequence of the inhibitor, except for an Ile/Leu substitution at position 59. Southern blot analysis of wheat-barley addition lines has shown that chromosome 3H of barley carries the gene for CMe. This protein is present at less than 2%–3% of the wild-type amount in the mature endosperm of the mutant Risø 1508 with respect to Bomi barley, from which it has been derived, and the corresponding steady state levels of the CMe mRNA are about I%. One or two copies of the CMe gene (synonym Itc1) per haploid genome have been estimated both in the wild type and in the mutant, and DNA restriction patterns are identical in both stocks, so neither a change in copy number nor a major rearrangement of the structural gene account for the markedly decreased expression. The mutation at the lys 3a locus in Risø 1508 has been previously mapped in chromosome 7 (synonym 5H). A single dose of the wild-type allele at this locus (Lys 3a) restores the expression of gene CMe (allele CMe-1) in chromosome 3H to normal levels. 相似文献
22.
Henry A. F. Stephens Robert W. Vaughan Lazaros I. Sakkas Ken I. Welsh Gabriel S. Panayi 《Immunogenetics》1989,30(3):149-155
Despite extensive analysis of the incidence ofHLA-DR andHLA-DQ allele frequencies in defined autoimmune disease groups, there is very little information available onHLA-DP allele frequencies. This is largely becauseHLA-DP typing has until recently been restricted to primed lymphocyte typing (PLT). However, allelic polymorphism of theHLA-DP subregion can now be studied by Southern blot analysis or genotyping withDPA1 andDPB1 probes. By direct counting of allele-specific DNA fragments, we have analyzed the frequencies of five majorDP genotypes (DPw1, DPw2, DPw3/6, DPw4, andDPw5), in a large number of Caucasoid rheumatoid arthritis (RA) patients (n=74), and controls (n=91). The predicted frequency
ofDP alleles in both patient and control groups was comparable to PLT-determinedDP allele frequencies in normal Caucasoids. However, the gene frequency ofDPw4 was increased in the RA patients, with 51% of the patients studied scoring asDPw4, 4 homozygotes. With the exception of one possible combination (DPw5 andDRw6) in the controls, no significant linkage disequilibrium was detected betweenDP andDR alleles in either patient or control groups. Thus the prevalence ofDPw4 in the RA patients is independent of any disease association with theDR loci, and may represent a new class II association with RA. 相似文献
23.
Mating behavior in seaweed flies (Coelopa frigida) 总被引:1,自引:0,他引:1
24.
Cannibalism as a life boat mechanism 总被引:2,自引:0,他引:2
Under certain conditions a cannibalistic population can survive when food for the adults is too scarce to support a non-cannibalistic population. Cannibalism can have this lifeboat effect if (i) the juveniles feed on a resource inaccessible to the adults; and (ii) the adults are cannibalistic and thus incorporate indirectly the inaccessible resource. Using a simple model we conclude that the mechanism works when, at low population densities, the average yield, in terms of new offspring, due to the energy provided by one cannibalized juvenile is larger than one. 相似文献
25.
Galanin-Like Immunoreactivity Is Unchanged in Alzheimer''s Disease and Parkinson''s Disease Dementia Cerebral Cortex 总被引:1,自引:1,他引:0
M. Flint Beal Ross A. Clevens Geetinder K. Chattha Usha M. MacGarvey Michael F. Mazurek Steven M. Gabriel 《Journal of neurochemistry》1988,51(6):1935-1941
Galanin is a recently isolated neuropeptide that is of particular interest in dementing disorders because of its known colocalization with choline acetyltransferase in magnocellular neurons of the basal nucleus of Meynert. These neurons degenerate in Alzheimer's disease, and there is a corresponding deficiency of cortical choline acetyltransferase activity. In the present study, galanin-like immunoreactivity was measured in the postmortem cerebral cortex and hippocampus of 10 controls and 14 patients who had had Alzheimer's disease. Significant reductions of choline acetyltransferase activity (50-60%) were found in all regions examined; however, there was no significant effect on concentrations of galanin-like immunoreactivity. Similar measurements were made in postmortem tissues of 12 control and 13 demented Parkinsonian patients who had had Alzheimer-type cortical pathology. Choline acetyltransferase activity was again significantly decreased in all regions examined but there were no significant reductions in galanin-like immunoreactivity. Experimental lesions of the fornix in rats produced parallel significantly correlated reductions of both choline acetyltransferase activity and galanin-like immunoreactivity in the hippocampus. Galanin-like immunoreactivity in the human hypothalamus consisted of two molecular-weight species on gel-permeation chromatography, and two forms were resolved by reverse-phase HPLC. The paradoxical preservation of galanin-like immunoreactivity, despite depletion of the activity of choline acetyltransferase, with which it is colocalized, is as yet unexplained. Recent studies have shown that galanin inhibits both acetylcholine release in the hippocampus and memory acquisition; therefore, preserved galanin may exacerbate the cholinergic and cognitive deficits that accompany dementia. 相似文献
26.
Monoclonal antibodies to the main immunogenic region of the nicotinic acetylcholine receptor bind to residues 61-76 of the alpha subunit 总被引:7,自引:0,他引:7
T Barkas J M Gabriel A Mauron G J Hughes B Roth C Alliod S J Tzartos M Ballivet 《The Journal of biological chemistry》1988,263(12):5916-5920
Monoclonal antibodies (mAbs) to the main immunogenic region (MIR) bind to fusion proteins containing region 37-200 of the alpha chain of Torpedo, mouse, and chicken nicotinic acetylcholine receptor. In the case of the mouse alpha chain, these mAbs react with sequence 61-216 but not with 74-216. A synthetic peptide M1, containing residues 61-76 of the mouse alpha chain, also binds these anti-MIR mAbs, showing that all or part of their binding site is included in this region. The conformational dependence and epitope specificity of the mAbs are discussed. 相似文献
27.
Reduction of carbohydrates by tritiated borohydride resulted in the production of alditols or glycosides with characteristically divergent specific radioactivities. Simultaneous reduction of individual sugars in the presence of a reference standard, talose, permitted the assignment of a unique specific radioactivity with respect to talitol as 100%. A variety of structures was examined, including neutral hexoses, free and acetylated aminosugars, ketohexoses and glycosides containing a fixed pyranose ring adjacent to a carbonyl group. In the latter case, the resulting steric hindrance severely restricted the incorporation of tritium. In both of the ketohexoses tested, the minor product of the two epimeric alditols exhibited the higher specific radioactivity. In all cases, reduction produced a characteristic and reproducible specific activity in which the values varied from 51 to 182% of that found for talose. These results are interpreted on the basis of generalizations concerning mechanism and predictive value. 相似文献
28.
Host-Symbiont Specificity Expressed during Early Adsorption of Rhizobium meliloti to the Root Surface of Alfalfa 总被引:7,自引:1,他引:6 下载免费PDF全文
Early (4 h) adsorption of Rhizobium meliloti L5-30 in low numbers to alfalfa roots in mineral solution was examined for competition with other bacterial strains. All tested competitor strains decreased the adsorption of L5-30 by extents which depended on the strain and its concentration. The decrease of adsorption by R. meliloti competitors (all of them infective in alfalfa) was nearly complete at saturation (97 to 99% decrease). All other heterologous rhizobia and Agrobacterium tumefaciens at saturating concentrations (106 to 107 per ml) decreased adsorption of L5-30 only partially, less than 60%. The differential effects of homologous and heterologous competitors indicate that initial adsorption of R. meliloti to the root surface of its host occurs in symbiont-specific as well as nonspecific modes and suggest the existence of binding sites on roots which are highly selective for the specific microsymbiont in the presence of other heterologous bacteria even in very unfavorable (less than 10−4) symbiont-competitor concentration ratios. 相似文献
29.
Gabriel Ahombo John C. Willison Paulette M. Vignais 《Molecular & general genetics : MGG》1986,205(3):442-445
Summary A 15.2 kb DNA fragment was isolated from Rhodobacter capsulatus (ex. Rhodopseudomonas capsulata), which was able to complement mutations both in a nifA-like regulatory gene and in the nifH gene. Physical mapping of this fragment revealed that the nifA-like gene was adjacent to, and downstream from, the nifHDK operon. Hybridization experiments were carried out using a cloned Klebsiella pneumoniae DNA fragment containing nifA and the flanking portions of nifB and nifL. This fragment failed to hybridize with a 2.15 kb HindIII fragment of R. capsulatus DNA containing the nifA-like gene, but hybridized instead with a 2.6 kb EcoRI fragment adjacent to the nifA-like gene. The homologous region was found to be located within the K. pneumoniae nifB gene. The adjacent 2.6 kb and 2.15 kb fragments also hybridized with each other, indicating the presence of repeated sequences in this region. 相似文献
30.
Holographic relaxation spectroscopy has been used to measure tracer diffusion coefficients for photochromically labeled bovine serum albumin in solutions having total bovine serum albumin concentrations in the range 3.25 to 257 g/liter. In the limit of zero concentration, the diffusion coefficient (20 degrees C, 0.1 M NaCl, 0.05 M Tris, pH 8.0) was found to be (5.9 +/- 0.1) X 10(-7) cm2/s and the initial slope was zero. The concentration dependence of the diffusion coefficient was not significantly affected by the fraction of protein molecules which were labeled. Holographic relaxation spectroscopy permits rapid, accurate determination of tracer diffusion coefficients for proteins in mixtures. 相似文献