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排序方式: 共有193条查询结果,搜索用时 15 毫秒
1.
The effect of helium-neon laser radiation (lambda = 633 nm) given to E. coli K-12 cells of various genotypes 4 h following X- or alpha-irradiation was shown to increase the number of viable cells. The irreversible ingradient of a radiation injury to cells remained invariable during the first 60 min after irradiation its values being minimal. 相似文献
2.
The short-term cooling of hen eggs under incubation was studied for its effect on the dynamics of the activity of cytochrome oxidase (CO) and anion ATPase in the brain and liver of 15- and 20-day hen embryos and 5-day chickens. The temperature fall in the embryonal period was established to stimulate the activity of bicarbonate-dependent ATPase in the brain and to suppress it in the liver tissue. The CO activity was also subjected to similar alterations. 相似文献
3.
We have isolated the delta-globin gene of the New-World spider monkey,
Ateles geoffroyi, and compared its nucleotide sequence with those of other
primate delta- and beta-globin genes. Among primate delta-globin genes, the
rate of nonsynonymous substitutions is much less than the rate of
synonymous substitutions. This suggests that primate delta- globin genes
may remain under evolutionary conservation, perhaps because hemoglobin A2
has an as yet unknown physiological importance.
相似文献
4.
The cooling of hen incubated eggs to 28 degrees C brings to disconnection of oxidative phosphorylation in brain on the 12th day of development. The addition of DNP (5 x 10(-5) M) takes off the cooling effect. 相似文献
5.
Analysis of insulin-specific T cell clones. I. Strategy for production of clonotypic antibody 总被引:1,自引:0,他引:1
S R Abromson-Leeman H Der Simonian M Clabby H Cantor 《Journal of immunology (Baltimore, Md. : 1950)》1986,136(9):3184-3188
A novel strategy for production of T cell clone-specific antiserum is described. Clones that are both antigen-specific and alloreactive can be injected in small numbers i.v. into a strain which expresses the appropriate alloantigens, inducing consistently high-titered antisera containing antibodies to the unique T cell receptor molecules on these cells. The antisera characterized in this report block activation of these cells by either antigen plus autologous class II products or alloantigen. Furthermore, in the absence of antigen, the antiserum strongly stimulates the specific clones to divide, and to synthesize and secrete various proteins. Consistent with the findings of other investigators, the antiserum immunoprecipitates a disulfide-linked dimer of 90,000 m.w. from the surfaces of cells with the appropriate specificity. 相似文献
6.
Biochemical pathways in prokaryotes can be traced backward through evolutionary time 总被引:10,自引:0,他引:10
For the first time, a credible prokaryotic phylogenetic tree is being
assembled by Woese and others using quantitative sequence analysis of
oligonucleotides in the highly conservative rRNA. This provides an
evolutionary scale against which the evolutionary steps that led to the
arrangement and regulation of contemporary biochemical pathways can be
measured. This paper presents an emerging evolutionary picture of aromatic
amino acid biosynthesis within a large superfamily assemblage of
prokaryotes that is sufficiently developed to illustrate a new perspective
that will be applicable to many other biochemical pathways.
相似文献
7.
In Drosophila pseudoobscura, the amylase (Amy) multigene family is
contained within a series of inversions, or gene arrangements, on the third
chromosome. The Standard (ST), Santa Cruz (SC), and Tree Line (TL)
inversions are central to the phylogeny of arrangements, and have clusters
of other arrangements derived from them. The gene arrangements belonging to
each of these three clusters have a characteristic number of Amy genes,
ranging from three in ST to two in SC to one in TL. This distribution
pattern can reflect a history of either duplications or deletions, although
the data available in the past did not permit a decision between these
alternatives. We provide unambiguous evidence that three Amy genes were
present before the divergence of the ST, SC, and TL arrangements. Thus, the
current status of the Amy multigene family is the result of deletions in
the TL and SC arrangements, which created three new pseudogenes: TL
Amy2-psi, TL Amy3-psi, and SC Amy3- psi. Analysis of pseudogene sequences
revealed that, in the SC and ST arrangements, pseudogene evolution has been
retarded, most likely due to the homogenization effect of gene conversion.
Finally, by determining the original copy number, we have reconstructed the
evolutionary history of the Amy multigene family and linked it with the
evolution of the central gene arrangements.
相似文献
8.
The application of sensory methodology for measuring deodorizing effect of an air conditioner equipped with electric plasma was introduced. Deodorizing effect was measured using chemical and sensory methods at different time (0, 30 and 60 min) and mode (control, blowing and cooling) of an air conditioner. Smoke from a roll of cigarette in a closed room was used as a source of odor and the concentrations of acetic acid and ammonia were measured as odorous chemical components. As one of the sensory methods triangle test was used and as a first step to obtain deodorizing effects by triangle test, the threshold of each panelist was obtained as the log dilution ratio of odor concentration at which the difference from odorless air was detected. The odor concentration at each time and mode was calculated using the threshold of the panel and the deodorizing effect was obtained on the basis of the odor concentration. In addition to a triangle test, scaling methods such as category scaling or magnitude estimation were used to measure deodorizing effect of an air conditioner. Deodorizing effects by scaling methods were calculated based on odor intensity with time at each mode. The regression analysis was done between the efficacy of deodorizing effect by sensory test and those by acetic acid and ammonia, the R2 values of the regression equations for triangle test, category scale, and magnitude estimation were 0.84, 0.72 and 0.69, respectively. Deodorizing effect by triangle test explained the decrease of acetic acid and ammonia better than those by category scaling or magnitude estimation while high cost and time consuming labor involved in triangle tests reduced the merit. The results of this study demonstrated that various sensory methods could be used to measure deodorizing effect of air conditioners and further researches on fast and reliable methods are needed to establish the official procedures. 相似文献
9.
10.
Inducer T lymphocytes synthesize and secrete peptides that stimulate growth and differentiation of many cell types, including lymphocytes and monocytes that kill foreign organisms, B lymphocytes, mast cells and hematopoietic precursor cells. To define these inducer molecules more precisely, we have generated clones of these T cells as a source of homogeneous material for biochemical analysis. These clones synthesize peptides that stimulate T and B cells to divide and that also induce the latter cells to secrete immunoglobulin. Inducer cells synthesize a 14 kilodalton growth polypeptide that stimulates T and B lymphocytes, as well as other cell types, to divide. This 14 kilodalton peptide is normally associated with different, larger peptides that appear to focus its mitogenic activity to one or another target cell. 相似文献