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Biomedical subjects

R M Kuhn

Publications and source records attributed to R M Kuhn.

8 recordsLinked to original sources
PubMed2006

The UCSC genome browser database: update 2007.

The University of California, Santa Cruz Genome Browser Database contains, as of September 2006, sequence and annotation data for the genomes of 13 vertebrate and 19 invertebrate species. The Genome Browser displays a wide variety of annotations at all scales from the single nucleotide level up to a full chromosome and includes assembly data, genes and gene predictions, mRNA and EST alignments, and comparative genomics, regulation, expression and variation data. The database is optimized for fast interactive performance with web tools that provide powerful visualization and querying capabilities for mining the data. In the past year, 22 new assemblies and several new sets of human variation annotation have been released. New features include VisiGene, a fully integrated in situ hybridization image browser; phyloGif, for drawing evolutionary tree diagrams; a redesigned Custom Track feature; an expanded SNP annotation track; and many new display options. The Genome Browser, other tools, downloadable data files and links to documentation and other information can be found at http://genome.ucsc.edu/.

Animals↗
PubMed2006

The UCSC Genome Browser Database: update 2006.

The University of California Santa Cruz Genome Browser Database (GBD) contains sequence and annotation data for the genomes of about a dozen vertebrate species and several major model organisms. Genome annotations typically include assembly data, sequence composition, genes and gene predictions, mRNA and expressed sequence tag evidence, comparative genomics, regulation, expression and variation data. The database is optimized to support fast interactive performance with web tools that provide powerful visualization and querying capabilities for mining the data. The Genome Browser displays a wide variety of annotations at all scales from single nucleotide level up to a full chromosome. The Table Browser provides direct access to the database tables and sequence data, enabling complex queries on genome-wide datasets. The Proteome Browser graphically displays protein properties. The Gene Sorter allows filtering and comparison of genes by several metrics including expression data and several gene properties. BLAT and In Silico PCR search for sequences in entire genomes in seconds. These tools are highly integrated and provide many hyperlinks to other databases and websites. The GBD, browsing tools, downloadable data files and links to documentation and other information can be found at http://genome.ucsc.edu/.

Amino Acid Sequence↗
PubMed1996

Chromophore-bearing NH2-terminal domains of phytochromes A and B determine their photosensory specificity and differential light lability.

In early seedling development, far-red-light-induced deetiolation is mediated primarily by phytochrome A (phyA), whereas red-light-induced deetiolation is mediated primarily by phytochrome B (phyB). To map the molecular determinants responsible for this photosensory specificity, we tested the activities of two reciprocal phyA/phyB chimeras in diagnostic light regimes using overexpression in transgenic Arabidopsis. Although previous data have shown that the NH2-terminal halves of phyA and phyB each separately lack normal activity, fusion of the NH2-terminal half of phyA to the COOH-terminal half of phyB (phyAB) and the reciprocal fusion (phyBA) resulted in biologically active phytochromes. The behavior of these two chimeras in red and far-red light indicates: (i) that the NH2-terminal halves of phyA and phyB determine their respective photosensory specificities; (ii) that the COOH-terminal halves of the two photoreceptors are necessary for regulatory activity but are reciprocally inter-changeable and thus carry functionally equivalent determinants; and (iii) that the NH2-terminal halves of phyA and phyB carry determinants that direct the differential light lability of the two molecules. The present findings suggest that the contrasting photosensory information gathered by phyA and phyB through their NH2-terminal halves may be transduced to downstream signaling components through a common biochemical mechanism involving the regulatory activity of the COOH-terminal domains of the photoreceptors.

Amino Acid Sequence↗
PubMed1993

DNA binding factor GT-2 from Arabidopsis.

Complementary DNA clones encoding a DNA-binding factor have been obtained from Arabidopsis by DNA hybridization with a GT-2 factor cDNA clone from rice. The GT-2 gene appears to be present as a single copy in the Arabidopsis genome and is transcribed as a 2.1 kb mRNA which is not light-regulated. The longest open reading frame in the sequenced clones predicts a protein of 65 kDa, beginning with the first in-frame methionine. The protein contains basic, acidic, and proline/glutamine-rich motifs and has significant amino acid sequence homology to the rice GT-2 factor, including three regions of 50-75 amino acids each of greater than 60% identity. Two of these regions are predicted to form similar trihelix structures postulated to be involved in selective binding to specific variations of a GT-box motif DNA sequence found in the promoter regions of several plant genes. Except for weak similarity to a tobacco GT-box binding factor, GT-1a/B2F, Arabidopsis GT-2 has no similarity to other sequences in the databases. DNA-binding studies show that Arabidopsis GT-2 has binding characteristics similar to those of the rice GT-2 factor, but dissimilar to those of the tobacco GT-1a/B2F factor. The data indicate that a DNA-binding factor containing domains of similar structure and target-sequence specificity has been conserved between monocots and dicots.

Amino Acid Sequence↗
PubMed1991

Clustered tRNA genes in Schizosaccharomyces pombe centromeric DNA sequence repeats.

The centromere-associated B' and B DNA sequence repeats of Schizosaccharomyces pombe chromosomes I and II have been found to contain clusters of tRNA genes. The centromere II region (cen2) includes at least 22 tRNA genes distributed among five copies of the B sequence repeat containing genes specifying tRNA(Ile), tRNA(Ala), and tRNA(Val). Individual B repeats are variously associated with other tRNA genes, including those specifying tRNA(Lys), tRNA(Arg), and tRNA(Glu2). The centromere I region (cen1) contains at least six tRNA genes in two copies of the B' repeated element, including genes specifying tRNA(Ile), tRNA(Ala), and tRNA(Glu3). Multiple tandemly arranged clusters of tRNA genes are presumably conserved due to restricted recombination frequencies in the centromere regions.

Base Sequence↗
PubMed1985

Unequal homologous recombination between tandemly arranged sequences stably incorporated into cultured rat cells.

Cultured rat cells deficient in endogenous thymidine kinase activity (tk) were stably transformed with a recombination-indicator DNA substrate constructed in vitro by rearrangement of the herpes simplex virus tk gene sequences into a partially redundant permutation of the functional gene. The recombination-indicator DNA did not express tk, but was designed to allow formation of a functional tk gene via homologous recombination. A clonal cell line (519) was isolated that harbored several permuted herpes simplex virus tk genes. 519 cells spontaneously produced progeny that survived in medium containing hypoxanthine, aminopterin, and thymidine. Acquisition of resistance to hypoxanthine, aminopterin, and thymidine was accompanied by the rearrangement of the defective tk gene to functional configuration. The rearrangement apparently occurred by unequal exchange between one permuted tk gene and a replicated copy of itself. Recombination was between 500-base-pair tracts of DNA sequence homology that were separated by 3.4 kilobases. Exchanges occurred spontaneously at a frequency of approximately 5 X 10(-6) events per cell per generation. Recombination also mediated reversion to the tk- phenotype; however, the predominant mechanism by which cells escaped death in the presence of drugs rendered toxic by thymidine kinase was not recombination, but rather inactivation of the intact tk gene.

Animals↗
PubMed1980

Some adaptive strategies for inadequate sample acquisition in veterans administration cooperative clinical trials.

A major concern of any clinical trial is being able to recruit sufficient patients of the proper type so that reliable answers can be obtained for the hypotheses being tested. This article considers patient recruitment in seven VA cooperative studies and the adaptive strategies used for inadequate sample acquisition. These strategies are: (1) the re-evaluation of the required sample size; (2) the addition of new hospitals; (3) the replacement of poor recruiting hospitals; (4) the extension of the patient intake period; and (5) the modification of the patient exclusion-inclusion criteria. When there is no expectation of achieving the required sample size in a reasonable time, the study is terminated. Although each of the five strategies will increase the likelihood of successfully completing a study should a recruitment problem occur, preventing these problems from occurring should be a major concern during the planning of a study.

Clinical Trials as Topic↗