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31.
Margaret B. Aydelotte Eugene J. M. A. Thonar Jürgen Mollenhauer Johannes Flechtenmacher 《In vitro cellular & developmental biology. Animal》1998,34(2):123-130
Summary Sodium alginate, which gels in the presence of calcium ions, is commonly used for culture of anchorage-independent cells,
such as chondrocytes. Normally, the gel appears microscopically homogeneous but, depending on the conditions of gelation,
it may contain a varying number of small channels that extend inward from the surface. We have examined the influence of these
channels on the morphology of cultured chondrocytes entrapped in alginate beads. Growth-plate or articular chondrocytes cultured
in alginate normally proliferate and form rounded cell clusters but, in alginate beads containing numerous channels, many
chondrocytes become aligned and form columns similar to those in the growth plate in vivo. As the pattern of cellular growth and morphology in alginate is profoundly influenced by the presence of channels in the
gel, further studies were conducted to determine what specific conditions of gelation affect their formation. The channels
are especially numerous when both the alginate and the gelling solutions lack sodium ions or other monovalent cations. The
channels are cavities in the gel formed by particulate blocking of the rapid diffusion of calcium ions from the gelling solution
into the boundary of the calcium alginate solution, and hence they extend inward from cells at the surface of the alginate
gel. An understanding of the conditions under which these channels develop makes it possible either to avoid their formation
or, alternatively, to enhance the number of channels in order to encourage proliferating cells to grow in radial columns,
rather than in a less organized pattern characteristic of most culture systems. 相似文献
32.
Isolated populations of drosophila pseudoobscura, separated from North
American populations by about 2,400 km, were found in Colombia in 1960. We
compared for sequences of the small ribosomal RNA (srRNA) gene on the
mitochondria between North American and Colombian D. pseudoobscura in order
to clarify the age of the Colombian isolates. The North American
populations were not genetically different from each other but were
genetically different from the Colombian populations. The Mexican strains
represent the area from which the Colombian founders might have come. The
estimated net nucleotide divergence between Mexican and Colombian D.
pseudoobscura indicates that the Colombian population is not an ancient
lineage. Phylogenies using both distance and parsimony methodologies
reinforced this conclusion. The Colombian samples group together with both
methods but, according to the bootstrap analysis, not significantly. It
appears that the populations have not been separated long enough for their
DNA sequences to show much divergence.
相似文献
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34.
INTRODUCTIONAsearlyasin1948wehavefr8CtionatedisolatednucleifromnormalandtumorcellsbyextractionwithiMNaCIanddilutealkali[1].Thenuclearresiduewasthenstudiedmorethoroughly[2,3].Lateron,sillillarproteinousnuclearresidueswereisolatedbyotherworkers[46]andasstud… 相似文献
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Background
Microsatellites are nucleotide sequences of tandem repeats occurring throughout the genome, which have been widely used in genetic linkage analysis, studies of loss of heterozygosity, determination of lineage and clonality, and the measurement of genome instability or the emergence of drug resistance reflective of mismatch repair deficiency. Such analyses may involve the parallel evaluation of many microsatellite loci, which are often limited by sample DNA, are labor intensive, and require large data processing.Results
To overcome these challenges, we developed a cost-effective high-throughput approach of microsatellite analysis, in which the amplifications of microsatellites are performed in miniaturized, multiplexed polymerase chain reaction (PCR) adaptable to 96 or 384 well plates, and accurate automated allele identification has been optimized with a collective reference dataset of 5,508 alleles using the GeneMapper software.Conclusions
In this investigation, we have documented our experience with the optimization of multiplex PCR conditions and automated allele identification, and have generated a unique body of data that provide a starting point for a cost-effective, high-throughput process of microsatellite analysis using the studied markers.37.
Eelke van der Horst Julio E Peironcely Adriaan P IJzerman Margot W Beukers Jonathan R Lane Herman WT van Vlijmen Michael TM Emmerich Yasushi Okuno Andreas Bender 《BMC bioinformatics》2010,11(1):316
Background
G protein-coupled receptors (GPCRs) represent a family of well-characterized drug targets with significant therapeutic value. Phylogenetic classifications may help to understand the characteristics of individual GPCRs and their subtypes. Previous phylogenetic classifications were all based on the sequences of receptors, adding only minor information about the ligand binding properties of the receptors. In this work, we compare a sequence-based classification of receptors to a ligand-based classification of the same group of receptors, and evaluate the potential to use sequence relatedness as a predictor for ligand interactions thus aiding the quest for ligands of orphan receptors. 相似文献38.