8 research outputs found

    An open reading frame upstream from the nifH gene of Klebsiella pneumoniae

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    An open reading frame upstream from nifHDK operon of Klebsiella pneumoniae had been described. The orientation of this open reading frame is opposite to that of nifHDK and sequence homology was found between the open reading frame promoter and the promoter of nifHDK operon. A recombinant plasmid carrying the promoter region of the open reading frame fused to the beta-galactosidase gene was constructed. Strains of E.coli were transformed with the plasmid containing this open reading frame promoter-lacZ fusion or co-transformed with it and a plasmid carrying the nifA gene. An appreciable activity of beta-galactosidase was found in strains which received both plasmids, indicating that the promoter of the open reading frame can be activated by the product of nifA gene. Thus, the open reading frame found between nifHDK operon and nifJ behaves just like other nif genes of K.pneumoniae in requiring the product of nifA as the positive effector for expression

    Genetics and Biochemistry of the Cysteine-Tyrosine Relationship in Neurospora crassa

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    NOTE: Text or symbols not renderable in plain ASCII are indicated by [...]. Abstract is included in .pdf document. Mutant 84605 which was obtained from wild type Neurospora crassa following X-ray treatment differs from wild type by a single gene located 4.8 units from the centromere of the second chromosome. At 25 [degrees], the mutant requires both cysteine and tyrosine for normal growth. At 35[degrees] only cysteine is required. The block in cysteine synthesis is the step sulfite [...] thiosulfate. High tyrosinase activity was found in the mutant grown at 25[degrees], but not when grown at 35[degrees]. Under the same conditions, wild type shows little or no tyrosinase activity. The addition of cysteine to the medium causes an inhibition of the growth of wild type, and at the same time a marked increase in the tyrosinase activity occurs. The inhibition can be overcome by adding tyrosine to the medium, or by culturing at 35[degrees]. It is suggested that the tyrosine requirement is caused by the high tyrosinase activity and that the latter, in turn, is caused by the defect in sulfur metabolism. Two natural inhibitors of tyrosinase have been found in Neurospora. A powerful inhibitor of the growth of wild type accumulates in cultures of the mutant. Experiments designed to test whether sulfide can serve as a sulfur source for Neurospora indicate that sulfide is utilized slightly, if at all. Experiments with a double mutant have indicated that the production of cysteine from methionine by Neurospora does not involve simple reversal of the step homocysteine [...] methionine.</p

    An open reading frame upstream from the nifH

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    Fractionated evaluation of immunohistochemical hormone receptor expression enhances prognostic prediction in breast cancer patients treated with tamoxifen as adjuvant therapy*

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    Objective: To compare the prognostic prediction between dichotomized and fractionated evaluations of hormone receptor expressions. Methods: Patients with stages I–III breast cancers, who received adjuvant tamoxifen, were enrolled. The expression of estrogen receptor (ER) and progesterone receptor (PR) was evaluated by immunohistochemistry (IHC). A fractionated score (F score), the percentage of positive-staining nuclei (0=none, 1=1%–10%, 2=11%–30%, 3=31%–50%, 4=51%–70%, and 5=71%–100%), was assigned to each case. The dichotomized scoring method defines an F score >1 as positive. The prognostic values of both scores were compared by multiple Cox’s proportional hazard models of disease-free survival (DFS) and overall survival (OS). Results: Four hundred and sixteen patients with a median follow-up of 78.0 months were included. F scores for ER and PR correlated directly with DFS and OS. Although both the dichotomized and fractionated ER and PR scores were significantly associated with DFS and OS in univariate analyses, only fractionated ER and PR scores remained as independent prognostic factors of DFS and OS in the final multiple Cox’s proportional hazard models. Conclusion: Fractionated IHC hormone receptor expression evaluation enhances the prognostic prediction compared with a dichotomized assessment
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