排序方式: 共有43条查询结果,搜索用时 0 毫秒
31.
采用关联指数(IC)和决定系数(CD)两种方法,度量混合线性模型遗传评估下猪群体间的遗传关联性。结果表明,加拿大安大略省的大约克夏猪、长白猪、杜洛克猪和汉普夏猪4个主要品种群体间具有良好的遗传联系。CD法既组合了数据结构和信息量,又考虑了预测误差方差和遗传变异性,是一个选择判断遗传评估精度的好方法。 相似文献
32.
33.
Thymidine kinase-deficient herpes simplex virus type 2 genital infection in guinea pigs. 总被引:5,自引:1,他引:4 下载免费PDF全文
In guinea pigs, thymidine kinase-producing strains of herpes simplex virus type 2 replicated to high titer in the vagina and spinal cord, and animals developed severe clinical disease. Infection with thymidine kinase-deficient virus resulted in similar vaginal virus titers; however, animals exhibited little or no clinical illness and only low titers of virus were detected in spinal cord homogenate cultures. Neural and extraneural latent infection as well as recurrent infection were noted in animals inoculated with either thymidine kinase-producing or -deficient viruses. These data suggest that neural pathways are important in the pathogenesis of genital herpes and that virus-coded thymidine kinase may influence virulence but is not required for latency. 相似文献
34.
A requirement for trypsin-sensitive cell-surface components for cell-cell interactions of embryonic neural retina cells 总被引:5,自引:3,他引:2 下载免费PDF全文
A quantitative assay was used to measure the rate of collection of a population of embryonic neural retina cells to the surface of cell aggregates. The rate of collection of freshly trysinized cells was limited in the initial stages by the rate of replacement of trypsin-sensitive cell- surface components. When cells were preincubated, or "recovered," and then added to cell aggregates, collection occurred at a linear rate and was independent of protein and glycoprotein synthesis. The adhesion of recovered cells was temperature and energy dependent, and was reversibly inhibited by cytochalasin B. Colchicine had little effect on collection of recovered cells. Antiserum directed against recovered cell membranes was shown to bind to recovered cells by indirect immunofluorescence. The antiserum also was shown to inhibit collection of recovered cells to aggregates, suggesting that at least some of the antigens identified might be involved in the adhesion process. The inhibitory effect of the antiserum was dose dependent . Freshly trypsinized cells absorbed neither the immunofluorescence activity nor the adhesion-inhibiting activity. Recovered cells absorbed away both activities. In specificity studies, dorsal neural retina cells adhered to aggregates of ventral optic tectum in preference to aggregates of dorsal optic tectum. The adhesive specificity of the dorsal retina cells was less sensitive to trypsin than the adhesive specificity of ventral retina cells which adhered preferentially to dorsal tectal aggregates only after a period of recovery. 相似文献
35.
36.
37.
Our study was designed to examine how components of complex mixtures can
inhibit the binding of other components to receptor sites in the olfactory
system of the spiny lobster Panulirus argus. Biochemical binding assays
were used to study how two- to six-component mixtures inhibit binding of
the radiolabeled odorants taurine, L-glutamate and
adenosine-5'-monophosphate to a tissue fraction rich in dendritic membrane
of olfactory receptor neurons. Our results indicate that binding inhibition
by mixtures can be large and is dependent on the nature of the odorant
ligand and on the concentration and composition of the mixture. The binding
inhibition by mixtures of structurally related components was generally
predicted using a competitive binding model and binding inhibition data for
the individual components. This was not the case for binding inhibition by
most mixtures of structurally unrelated odorants. The binding inhibition
for these mixtures was generally smaller than that for one or more of their
components, indicating that complex binding interactions between components
can reduce their ability to inhibit binding. The magnitude of binding
inhibition was influenced more by the mixture's precise composition than by
the number of components in it, since mixtures with few components were
sometimes more inhibitory than mixtures with more components. These
findings raise the possibility that complex binding interactions between
components of a mixture and their receptors may shape the output of
olfactory receptor neurons to complex mixtures.
相似文献
38.
Noncontact dipole effects on channel permeation. III. Anomalous proton conductance effects in gramicidin 总被引:3,自引:2,他引:1 下载免费PDF全文
LR Phillips CD Cole RJ Hendershot M Cotten TA Cross DD Busath 《Biophysical journal》1999,77(5):2492-2501
Proton transport on water wires, of interest for many problems in membrane biology, is analyzed in side-chain analogs of gramicidin A channels. In symmetrical 0.1 N HCl solutions, fluorination of channel Trp(11), Trp-(13), or Trp(15) side chains is found to inhibit proton transport, and replacement of one or more Trps with Phe enhances proton transport, the opposite of the effects on K(+) transport in lecithin bilayers. The current-voltage relations are superlinear, indicating that some membrane field-dependent process is rate limiting. The interfacial dipole effects are usually assumed to affect the rate of cation translocation across the channel. For proton conductance, however, water reorientation after proton translocation is anticipated to be rate limiting. We propose that the findings reported here are most readily interpreted as the result of dipole-dipole interactions between channel waters and polar side chains or lipid headgroups. In particular, if reorientation of the water column begins with the water nearest the channel exit, this hypothesis explains the negative impact of fluorination and the positive impact of headgroup dipole on proton conductance. 相似文献
39.
Mitochondrial DNA variation and genetic structure in populations of Drosophila melanogaster 总被引:5,自引:0,他引:5
The understanding of the genetic structure of a species can be improved by
considering together data from different types of genetic markers. In the
past, a number of worldwide populations of Drosophila melanogaster have
been extensively studied for several such markers, including allozymes,
chromosomal inversions, and quantitative characters. Here we present
results from a study of restriction- fragment-length polymorphisms of
mitochondrial DNA (mtDNA) in 92 isofemale lines from many of the same
geographic populations of D. melanogaster. Eleven restriction enzymes were
used, of which four revealed restriction-site polymorphism. A total of 24
different haplotypes were observed, of which 18 were unique to single
populations. In many populations, the unique haplotypes have reached high
frequency without being observed in neighboring populations. A Wagner
parsimony tree reveals that mutationally close variants show geographical
clumping, suggesting local differentiation of mtDNA in populations. The
Old-World and the New-World populations are differentiated, with the
predominant Old-World haplotype being virtually absent from the New World.
These results contrast with those for the nuclear genes, in which many loci
show parallel clines in different continents, and suggest a common origin
of D. melanogaster populations in North America.
相似文献
40.
Winston A. Haynes Roger Higdon Larissa Stanberry Dwayne Collins Eugene Kolker 《PLoS computational biology》2013,9(3)
Life science technologies generate a deluge of data that hold the keys to unlocking the secrets of important biological functions and disease mechanisms. We present DEAP, Differential Expression Analysis for Pathways, which capitalizes on information about biological pathways to identify important regulatory patterns from differential expression data. DEAP makes significant improvements over existing approaches by including information about pathway structure and discovering the most differentially expressed portion of the pathway. On simulated data, DEAP significantly outperformed traditional methods: with high differential expression, DEAP increased power by two orders of magnitude; with very low differential expression, DEAP doubled the power. DEAP performance was illustrated on two different gene and protein expression studies. DEAP discovered fourteen important pathways related to chronic obstructive pulmonary disease and interferon treatment that existing approaches omitted. On the interferon study, DEAP guided focus towards a four protein path within the 26 protein Notch signalling pathway. 相似文献