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Carmen Lai Marcel JT Reinders Laura J van't Veer Lodewyk FA Wessels 《BMC bioinformatics》2006,7(1):235
Background
Gene selection is an important step when building predictors of disease state based on gene expression data. Gene selection generally improves performance and identifies a relevant subset of genes. Many univariate and multivariate gene selection approaches have been proposed. Frequently the claim is made that genes are co-regulated (due to pathway dependencies) and that multivariate approaches are therefore per definition more desirable than univariate selection approaches. Based on the published performances of all these approaches a fair comparison of the available results can not be made. This mainly stems from two factors. First, the results are often biased, since the validation set is in one way or another involved in training the predictor, resulting in optimistically biased performance estimates. Second, the published results are often based on a small number of relatively simple datasets. Consequently no generally applicable conclusions can be drawn. 相似文献13.
B. Surek U. Beemelmanns M. Melkonian D. Bhattacharya 《Plant Systematics and Evolution》1994,191(3-4):171-181
The nuclear-encoded small subunit ribosomal RNA (rRNA) sequences were determined forGenicularia spirotaenia, Mesotaenium caldariorum, andStaurastrum spec. (Zygnematales) to elucidate the evolutionary position of these green algae. Results of neighbour-joining and maximum parsimony phylogenetic analyses support a monophyletic origin of theZygnematales within the evolutionary assemblage defined by theCharophyceae (sensuMattox & Stewart) and land plants. TheZygnematales/Charophyceae/land plants are evolutionarily distinct from the monophyletic lineage defined by theChlorodendrales, Pseudoscourfieldiales, and theMicrothamniales/Chlorophyceae.
In memoriamRobert W. Hoshaw. 相似文献
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Background
Cerebellar granule cell precursors are specifically generated within the hindbrain segment, rhombomere 1, which is bounded rostrally by the midbrain/hindbrain isthmus and caudally by the boundary of the Hoxa2 expression domain. While graded signals from the isthmus have a demonstrable patterning role within this region, the significance of segmental identity for neuronal specification within rhombomere 1 is unexplored. We examined the response of granule cell precursors to the overexpression of Hoxa2, which normally determines patterns of development specific to the hindbrain. How much does the development of the cerebellum, a midbrain/hindbrain structure, reflect its neuromeric origin as a hindbrain segment? 相似文献15.
Using circulant symmetry to model featureless objects 总被引:1,自引:0,他引:1
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Visualization of antigenic proteins blotted onto nitrocellulose using the immuno-gold-staining (IGS) method 总被引:3,自引:0,他引:3
A new and simple method for the detection of antigenic proteins blotted onto nitrocellulose was developed. After transfer of spinach stromal proteins and purified phosphoribulokinase immunolabeling was performed with phosphoribulokinase antiserum, followed by a) Protein A-labeled colloidal gold particles, and b) by horseradish peroxidase conjugated Protein A and substrate mixture. The Protein A-Gold method is at least twofold more sensitive than the Protein A-peroxidase procedure. Incubation of immunolabeled nitrocellulose replicas with 0.1 M glycine, pH 2.2, removes the antibody-Protein A-Gold complexes quantitatively without influencing the antigenicity of the immobilized proteins. The replicas can be re-used for immunostaining with other antisera. The versatile applicability of the immuno-gold-staining method suggests that it is a true alternative to the peroxidase assay. 相似文献
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Forbes SH; Hogg JT; Buchanan FC; Crawford AM; Allendorf FW 《Molecular biology and evolution》1995,12(6):1106-1113
We compared genotypes at eight (AC)n microsatellite loci in domestic sheep
(Ovis aries) and wild Rocky Mountain bighorn sheep (O. canadensis). The
domestic sheep had greater genetic variation, higher allele-size variances,
and larger allele sizes than the wild sheep. Accumulating evidence from
higher taxonomic comparisons shows that these parameters are biased if
microsatellite loci are selected in one taxon and used in another. Our
results demonstrate similar biases between congeneric species. We compared
standard measures of genetic variation, differentiation, and distance
within and between species (H, D, FST) to newer measures based on
allele-size variance (SW, SB, RST). The size-based distances better
detected species-level divergence, but standard measures better
distinguished allopatric populations. Empirical calibration of these
measures at the subspecies level is needed to establish their useful
ranges.
相似文献