Null Subject
Mostrando 25-36 de 65 artigos, teses e dissertações.
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25. PRB3 null mutations result in absence of the proline-rich glycoprotein Gl and abolish Fusobacterium nucleatum interactions with saliva in vitro.
The glycosylated proline-rich glycoprotein (Gl or PRG), a product of the PRB3 gene, is a major constituent of human parotid saliva. Important functions proposed for Gl include acting as a bacterial receptor. The Gl proteins of several subjects were typed by two polyacrylamide gel electrophoresis (PAGE) systems: acid-lactate PAGE followed by staining with the
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26. Stat1-independent regulation of gene expression in response to IFN-γ
Although Stat1 is essential for cells to respond fully to IFN-γ, there is substantial evidence that, in the absence of Stat1, IFN-γ can still regulate the expression of some genes, induce an antiviral state and affect cell growth. We have now identified many genes that are regulated by IFN-γ in serum-starved Stat1-null mouse fibroblasts. The proteins
The National Academy of Sciences.
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27. Evolutionary Analyses of DNA Sequences Subject to Constraints on Secondary Structure
Evolutionary models appropriate for analyzing nucleotide sequences that are subject to constraints on secondary structure are developed. The models consider the evolution of pairs of nucleotides, and they incorporate the effects of base-pairing constraints on nucleotide substitution rates by introducing a new parameter to extensions of standard models of seq
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28. Flagellar assembly in Caulobacter crescentus: a basal body P-ring null mutation affects stability of the L-ring protein.
The P- and L-rings are structural components of the flagellar basal body that are positioned in the periplasmic space and outer membrane, respectively. In order to explore the mechanism of P- and L-ring assembly, we examined the effect of a null mutation in the gene encoding the P-ring subunit, FlgI, on the expression, stability, and subcellular localization
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29. Positive Control of Swarming, Rhamnolipid Synthesis, and Lipase Production by the Posttranscriptional RsmA/RsmZ System in Pseudomonas aeruginosa PAO1†
In Pseudomonas aeruginosa, the small RNA-binding, regulatory protein RsmA is a negative control element in the formation of several extracellular products (e.g., pyocyanin, hydrogen cyanide, PA-IL lectin) as well as in the production of N-acylhomoserine lactone quorum-sensing signal molecules. RsmA was found to control positively the ability to swarm and to
American Society for Microbiology.
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30. Eyes or patients? Traps for the unwary in the statistical analysis of ophthalmological studies.
In reports on ophthalmological research the results of measurements on the eye are often expressed as mean and standard deviation based on m patients, n eyes (n greater than m). This approach leads to t tests that are invalid because the measurements on the two eyes of one subject are usually related, not independent. In a simulation study involving intraocu
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31. Hypercatabolism of C3 and C4 in active and inactive systemic lupus erythematosus.
The metabolism of the complement proteins C3 and C4 was studied in patients with active and inactive systemic lupus erythematosus (SLE) using highly purified, functionally active preparations. Nine patients with active and eight with inactive SLE were examined and 11 control subjects. There was a significant difference in the level of double stranded DNA ant
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32. The Saccharomyces cerevisiae ICL2 Gene Encodes a Mitochondrial 2-Methylisocitrate Lyase Involved in Propionyl-Coenzyme A Metabolism
The Saccharomyces cerevisiae ICL1 gene encodes isocitrate lyase, an essential enzyme for growth on ethanol and acetate. Previous studies have demonstrated that the highly homologous ICL2 gene (YPR006c) is transcribed during the growth of wild-type cells on ethanol. However, even when multiple copies are introduced, ICL2 cannot complement the growth defect of
American Society for Microbiology.
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33. Human piebald trait resulting from a dominant negative mutant allele of the c-kit membrane receptor gene.
Human piebald trait is an autosomal dominant defect in melanocyte development characterized by patches of hypopigmented skin and hair. Although the molecular basis of piebaldism has been unclear, a phenotypically similar "dominant spotting" of mice is caused by mutations in the murine c-kit protooncogene. In this regard, one piebald case with a point mutatio
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34. Modelling the secondary structures of slippage-prone hypervariable RNA regions: the example of the tiger beetle 18S rRNA variable region V4.
Variable regions within ribosomal RNAs frequently vary in length as a result of incorporating products of slippage. This makes constructing secondary structure models problematic because base homology is difficult or impossible to establish between species. Here, we model such a region by comparing the results of the MFOLD suboptimal folding algorithm for di
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35. A Statistical Test of a Neutral Model Using the Dynamics of Cytonuclear Disequilibria
In this paper we use cytonuclear disequilibria to test the neutrality of mtDNA markers. The data considered here involve sample frequencies of cytonuclear genotypes subject to both statistical sampling variation as well as genetic sampling variation. First, we obtain the dynamics of the sample cytonuclear disequilibria assuming random drift alone as the sour
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36. Conservation of Brown Gene Trans-Inactivation in Drosophila
The mechanism underlying trans-inactivation associated with dominant position effect variegation (PEV) of the Drosophila melanogaster brown gene has been addressed by a comparison with its D. virilis homologue. This comparison revealed: 86% identity between conceptual translation products of the brown gene from these two species, functional homology, as the