Mechthild Filser

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Three new genes nifM, nifI and nifN have been mapped in the nif gene cluster of Klebsiella pneumoniae and a fourth gene nifJ has been confirmed as being a separate cistron. Polar nif mutations were obtained by transposition of Tn7 to plasmid pRD1, and of Tn5 and Tn10 to plasmid pMF100, a derivative of pRD1. Complementation analysis of the nif::Tn mutants(More)
A total of nine regulatory mutations in the nifLA operon of Klebsiella pneumoniae were cloned in the high copy-number plasmid vector pACYC184. The regulatory phenotypes of the resultant clones were then correlated with their restriction maps and their ability to synthesise nifL and nifA polypeptides in vivo. One mutation, nifL2401, was identified as a 400(More)
The genome of the slow-growing Bradyrhizobium japonicum (strain 110) was mutagenized with transposon Tn5. A total of 1623 kanamycin/streptomycin resistant derivatives were screened in soybean infection tests for nodulation (Nod) and symbiotic nitrogen fixation (Fix). In this report we describe 14 strains possessing a stable, reproducible Nod+Fix- phenotype.(More)
Male Wistar rats exposed to atmosphericn-hexane excreted in their urine substances which gave rise to absorption spectra like those of pyrroles after the reaction with Ehrlich's reagent. A simple spectrophometric assay was developed to determine these “pyrrole-like substances” in urine. Their excretion kinetics were evaluated by exposing rats for 8 h to(More)
The transposons Tn5, Tn7 and Tn10 and bacteriophage Mu have been used to derive insertion mutations in the Klebsiella pneumoniae nif gene cluster. A large number of deletion mutants have been derived by imprecise excision of insertion mutations and these deletions have been used to construct a fine-structure map of the nif cluster. Comparison of this(More)
Analogues of the analgetic drug pethidine were synthesized. Two N-aralkylen derivatives displayed a superior inhibitory effect on the activity of NADH:ubiquinone reductase in beef heart mitochondrial membranes. Dose-response curves revealed that the potency of these compounds is very comparable to that of the standard probe rotenone. The inhibitors were(More)
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