Studies on dissimilatory sulfate-reducing bacteria that decompose fatty acids

Three strains (2ac9, 3ac10 and 4ac11) of oval to rodshaped, Gram negative, nonsporing sulfate-reducing bacteria were isolated from brackish water and marine mud samples with acetate as sole electron donor. All three strains grew in simple defined media supplemented with biotin and 4-aminobenzoic acid as growth factors. Acetate was the only electron donor utilized by strain 2ac9, while the other two strains used in addition ethanol and/or lactate. Sulfate served as electron acceptor and was reduced to H₂S. Complete oxidation of acetate to CO₂ was shown by stoichiometric measurements with strain 2ac9 in batch cultures using sulfate, sulfite or thiosulfate as electron acceptors. With sulfate an average growth yield of 4.8 g cell dry weight was obtained per mol of acetate oxidized; with sulfite or thiosulfate the growth yield on acetate was about twice as high. None of the strains contained desulfoviridin. In strain 2ac9 cytochromes of the b- and c-type were detected. Strain 2ac9 is described as type strain of the new species and genus, Desulfobacter postgatei.     

A new anaerobic,sporing, acetate-oxidizing,sulfate-reducing bacterium,Desulfotomaculum (emend.) acetoxidans

Archives of Microbiology - A new strictly anaerobic, polarly flagellated, sporing, acetate-oxidizing, sulfate-reducing bacterium was isolated from anaerobic fresh or sea water mud samples. The...     

Nucleophilic substitution at C-2 of S-alkylated 2-thiocytidines by cysteine and lysine : A new method for specific covalent linking of peptides to nucleic acids

S-Alkylated 2-thiocytidine can be substituted at C-2 by nucleophilic agents. This reaction has been investigated with model compounds as well as with tRNA using the amino acids cysteine and lysine in order to develop a new affinity label linking covalently tRNA and a protein. Reaction with N-protected cysteine gives 2-S-alkyl-pyrimidines, while unprotected cysteine yields an N-alkyl-pyrimidine, after intramolecular substitution. With the -amino group of lysine a fast replacement at C-2 is observed, leading to an unstable 2-N-alkyl-pyrimidine. All products have been characterized both chemically and spectroscopically.     

Mutations causing charge alterations in regulatory subunits of the cAMP-dependent protein kinase of cultured S49 lymphoma cells.

Two-dimensional polyacrylamide gel electrophoresis is used to visualize the regulatory subunit of cAMP-dependent protein kinase from cultured S49 mouse lymphoma cells and to demonstrate its in vivo phosphorylation. Regulatory subunits from mutant cells with altered kinases exhibit at least two patterns of charge shifts consistent with substitutions of single amino acids. The direct demonstration of structural alteration of this protein provides strong evidence for structural gene mutation in this cultured cell system. While mutant and wild-type gene products co-exist in the mutant cells, there is apparently preferential expression and phosphorylation of mutant subunit in these heterozygotes.     

Ein Endemit Zyperns:Asperula cypria (Rubiaceae) und seine Verwandtschaft

Galium suberosum Sibth. etSm. belongs toAsperula sect.Thliphthisa; the taxonomic transfer and a new name are therefore necessary:Asperula cypria Ehrend. is endemic on the isle of Cyprus. Its closest affinities are withA. antalyensis Ehrend. in S.W. Anatolia.

     

The mutagenic effect of benzene, toluene and xylene studied by the SCE technique.

In experiments in vitro, neither benzene, toluene nor xylene changed the number of sister-chromatid exchanges (SCEs) or the number of chromosomal aberrations in human lymphocytes. Toluene and xylene caused a significant cell growth inhibition which was not observed with benzene in the same concentrations.     

Bradykinin-induced oscillations of cell membrane potential in cells expressing the Ha-ras oncogene

Products of ras genes are putative elements of growth factor signal transduction. However, the mechanism of action of these proteins in normal and malignant growth is as yet obscure. To test for functional consequences of ras oncogene expression, electrophysiological experiments were performed on NIH-3T3 fibroblasts transfected with a transforming Ha-ras MMTV-LTR construct expressing the oncogene on treatment with dexamethasone (+ras). Transfected cells in the absence of dexamethasone (-ras) and nontransfected cells in the presence of dexamethasone (oras) served as controls. In -ras and oras, bradykinin induces a single, transient hyperpolarization. In +ras, bradykinin elicits oscillations of cell membrane potential throughout the presence of the hormone by activation of calcium-sensitive K+ channels. The oscillations of cell membrane potential are abolished in the absence of extracellular calcium. As evident from fura 2 fluorescence, bradykinin leads to a transient increase of intracellular calcium both in the presence and absence of extracellular calcium. Oscillations of intracellular calcium could be observed in +ras cells, if bradykinin was applied at reduced extracellular sodium concentration possibly to impair calcium extrusion via the sodium/calcium exchange. Bradykinin induces oscillations of cell membrane potential similarly in -ras cells loaded with GTP[S], a nonhydrolyzable analogue of GTP. Thus, the altered response of ras oncogene expressing cells to bradykinin relates to the GTP binding property of the ras protein. It is concluded that in cells expressing ras oncogene but not in other fibroblasts bradykinin mimicks the effect of growth factors on the cell membrane.     

Cloning, nucleotide sequence, and heterologous expression of a high-affinity nickel transport gene from Alcaligenes eutrophus.

High-affinity nickel transport in Alcaligenes eutrophus H16 is mediated by a function designated hoxN. hoxN lies within the hydrogenase gene cluster of megaplasmid pHG1. An insertional mutation at the hoxN locus led to an increased nickel requirement. In this mutant (strain HF260) both autotrophic growth on hydrogen and wild-type level of urease, a nickel-containing enzyme, were dependent on high concentration of nickel in the medium. Studies with a heterologous in vivo expression system revealed that the hoxN locus encodes two proteins with Mr = 30,000 and 28,000. Only the larger polypeptide was essential for nickel transport. The hoxN locus was cloned on a 2.2-kilobase pair fragment. Nucleotide sequence analysis of the hoxN locus revealed an open reading frame with a coding capacity for a protein of 33.1 kDa. The insertion leading to the Nic- phenotype of strain HF260 maps within this open reading frame indicating that it does in fact have coding function. The deduced amino acid sequence of the hoxN gene has several features typical of a hydrophobic integral membrane protein. Alkaline phosphatase fusion proteins produced by insertion of the transposon TnphoA into hoxN gave significant levels of alkaline phosphatase activity indicating that protein HoxN contains periplasmic domains. Taken together, our results suggest that gene hoxN encodes the high-affinity nickel transporter of A. eutrophus.     

Molecular cloning and characterization of a novel calcium channel from rabbit brain.

The complete amino acid sequence of a novel calcium channel (designated BII) from rabbit brain has been deduced by cloning and sequencing the cDNA. The BII calcium channel is structurally more closely related to the BI calcium channel than to the cardiac and skeletal muscle L-type calcium channels. Blot hybridization analysis of RNA from different tissues and from different regions of the brain shows that the BII calcium channel is distributed predominantly in the brain, being abundant in the cerebral cortex, hippocampus and corpus striatum.