Taxonomic description of Methanococcoides euhalobius and its transfer to the Methanohalophilus genus

A sequence analysis of the 16S-rRNA of Methanococcoides euhalobius revealed that this organism was highly related to members of the genus Methanohalophilus. On the basis of sequence data, an oligonucleotide probe specific to Methanohalophilus species was designed. Hybridization studies with this probe confirmed close relationship of Methanococcoides euhalobius to Methanohalophilus species. Therefore, we propose that Methanococcoides euhalobius should be transferred to the genus Methanohalophilus as Methanohalophilus euhalobius.     

The Phylogenetic Diversity of Aerobic Organotrophic Bacteria from the Dagang High-Temperature Oil Field

The distribution and species diversity of aerobic organotrophic bacteria in the Dagang high-temperature oil field (China), which is exploited with water-flooding, have been studied. Twenty-two strains of the most characteristic thermophilic and mesophilic aerobic organotrophic bacteria have been isolated from the oil stratum. It has been found that, in a laboratory, the mesophilic and thermophilic isolates grow in the temperature, pH, and salinity ranges characteristic of the injection well near-bottom zones or of the oil stratum, respectively, and assimilate a wide range of hydrocarbons, fatty acids, lower alcohols, and crude oil, thus exhibiting adaptation to the environment. Using comparative phylogenetic 16S rRNA analysis, the taxonomic affiliation of the isolates has been established. The aerobic microbial community includes gram-positive bacteria with a high and low G+C content of DNA, and γ and β subclasses of Proteobacteria. The thermophilic bacteria belong to the genera Geobacillus and Thermoactinomyces, and the mesophilic strains belong to the genera Bacillus, Micrococcus, Cellulomonas, Pseudomonas, and Acinetobacter. The microbial community of the oil stratum is dominated by known species of the genus Geobacillus (G. subterraneus, G. stearothermophilus, and G. thermoglucosidasius) and a novel species “Geobacillus jurassicus.” A number of novel thermophilic oil-oxidizing bacilli have been isolated.__________Translated from Mikrobiologiya, Vol. 74, No. 3, 2005, pp. 401–409.Original Russian Text Copyright © 2005 by Nazina, Sokolova, Shestakova, Grigoryan, Mikhailova, Babich, Lysenko, Tourova, Poltaraus, Qingxian Feng, Fangtian Ni, Belyaev.     

Effect of the periodic ripple in an axial confining magnetic field on the Alfvén heating of a cylindrical plasma

In a uniform axial magnetic field, the structure of local Alfvén resonance and the resonant absorption of RF power are governed by collisions, finite ion Larmor radius effects, and electron inertia. It is shown that, in a cylindrical plasma in a constant, periodically rippled, axial magnetic field, the structure of Alfvén resonance and the absorption of RF power can strongly depend on the ripple amplitude. The conditions under which the effect in question is dominant are intrinsic, e.g., to the modular Wendelstein stellarators.     

Neprilysin gene expression requires binding of the amyloid precursor protein intracellular domain to its promoter: implications for Alzheimer disease

Amyloid β‐peptide (Aβ) accumulation leads to neurodegeneration and Alzheimer disease; however, amyloid metabolism is a dynamic process and enzymic mechanisms exist for Aβ removal. Considerable controversy surrounds whether the intracellular domain of the amyloid precursor protein (AICD) regulates expression of the Aβ‐degrading metalloprotease, neprilysin (NEP). By comparing two neuroblastoma cell lines differing substantially in NEP expression, we show by chromatin immunoprecipitation (ChIP) that AICD is bound directly to the NEP promoter in high NEP‐expresser (NB7) cells but not in low‐expresser (SH‐SY5Y) cells. The methylation status of the NEP promoter does not regulate expression in these cells, whereas the histone deacetylase inhibitors trichostatin A and valproate partly restore NEP expression and activity in SH‐SY5Y cells. ChIP analysis also reveals AICD binding to the NEP promoter in rat primary neurons but not in HUVEC cells. Chromatin remodelling of crucial Alzheimer disease‐related genes by valproate could provide a new therapeutic strategy.     

The antidepressant-like effect of Ocimum basilicum in an animal model of depression

We investigated the efficacy of Ocimum basilicum (OB) essential oils for treating depression related behavioral, biochemical and histopathological changes caused by exposure to chronic unpredictable mild stress (CUMS) in mice and to explore the mechanism underlying the pathology. Male albino mice were divided into four groups: controls; CUMS; CUMS plus fluoxetine, the antidepressant administered for pharmacological validation of OB; and CUMS plus OB. Behavioral tests included the forced swim test (FST), elevated plus-maze (EPM) and the open ?eld test (OFT); these tests were performed at the end of the experiment. We assessed serum corticosterone level, protein, gene and immunoexpression of brain-derived neurotropic factor (BDNF) and glucocorticoid receptors (GRs) as well as immunoexpression of glial fibrillary acidic protein (GFAP), Ki67, caspase-3 in the hippocampus. CUMS caused depression in the mice as evidenced by prolonged immobility in the FST, prolonged time spent in the open arms during the EPM test and reduction of open field activity in the OFT. OB ameliorated the CUMS induced depressive status. OB significantly reduced the corticosterone level and up-regulated protein and gene expressions of BDNF and GR. OB reduced CUMS induced hippocampal neuron atrophy and apoptosis, and increased the number of the astrocytes and new nerve cells. OB significantly increased GFAP-positive cells as well as BDNF and GR immunoexpression in the hippocampus.     

Toxicity and SOS-response to ELF magnetic fields and nalidixic acid in E. coli cells

Extremely low-frequency magnetic fields (ELF-MF) have previously been shown to affect conformation of chromatin and cell proliferation. Possible genotoxic and carcinogenic effects of ELF-MF have also been discussed and tested. In this study, we analysed the effect of ELF-MF on chromatin conformation in E. coli GE499 cells by the anomalous viscosity time-dependence (AVTD) technique. Possible genotoxic effects of the specific combination of static and ELF-MF, which has been proven to affect chromatin conformation, were investigated by a clonogenic assay, by assessing cell-growth kinetics, and by analysis of the SOS-response by means of inducible recA-lacZ fusion-gene products and the β-galactosidase assay. The genotoxic agent nalidixic acid (NAL) was used as a positive control and in combination with ELF-MF. Nalidixic acid at 3-30μg/ml decreased the AVTD peaks and induced a cytotoxic effect. In contrast to NAL, ELF-MF fields increased AVTD, stimulated cell growth, and increased cloning efficiency. These effects depended on the frequency within the range of 7-11Hz. While NAL induced an SOS-response, exposure to ELF-MF did not induce the recA-lacZ fusion-gene product. Exposure to ELF-MF did not modify the genotoxic effects of NAL either. All together, the data show that ELF-MF, under specific conditions of exposure, acted as a non-toxic but cell-growth stimulating agent.     

Diagnostics of ataxia-telangiectasia by an express test based on the indirect immunofluorescence method

Ataxia-telangiectasia (AT) is a severe hereditary neurodegenerative disease developing in the presence of mutations in both alleles of the gene atm. This gene encodes the key protein of cell response to DNA damage—ATM protein kinase. During the appearance of double-strand DNA breaks, the ATM protein kinase is autophosphorylated and its active form appears in the cell—phospho-ATM (P-ATM)—revealed by a modified method of indirect immunofluorescence. In nuclei of cells containing the normal gene atm, after the effect of agents producing double-strand DNA breaks, P-ATM is detected, whereas in the cells carrying mutant variants of the gene atm P-ATM is not found. This peculiarity can be used in clinics for confirmation of diagnosis of AT in complicated cases.     

Euchromatic domains in plant chromosomes as revealed by H4 histone acetylation and early DNA replication.

Using specific polyclonal antisera raised against acetylated isoforms of histone H4, we have analyzed their distribution in the dioecious plant Silene latifolia (syn. Melandrium album) possessing heteromorphic sex chromosomes. Our previous studies on this species have shown that one of the two X chromosomes in homogametic female cells is heavily methylated and late replicating, as a possible consequence of dosage compensation. Here we report that there are no detectable differences in intensity and distribution of H4 acetylation between these two X chromosomes. In S. latifolia only distal-subtelomeric chromosome regions, on both the sex chromosomes and autosomes, display strong signals of H4 acetylation at N-terminal lysines 5, 8, and 12. These acetylated domains correspond to the very early replicating distal chromosome regions as revealed by 5-bromodeoxyuridine pulses followed by the indirect immunofluorescence microscopy. The distribution of H4 acetylated at lysine 16 was uniform along the chromosomes. The unique distal-subtelomeric H4 acetylation signals were also observed in three other Silene species (S. vulgaris, S. pendula, and S. chalcedonica), but not in two non-related plant species tested (Allium cepa and Nicotiana tobacum). The presented data as well as our recent studies on the structure of S. latifolia chromosome ends indicate that Silene species possess the specific distal-subtelomeric location of euchromatin, gene-rich regions on chromosomes.     

Cell density dependent response of E. Coli cells to weak ELF magnetic fields

The effects of weak magnetic fields of extremely low frequency (ELF) on E. coli K12 AB1157 cells were studied by the method of anomalous viscosity time dependencies (AVTD). E. coli cells at different densities within a range of 5 × 10⁵–10⁹ cell/ml were exposed to ELF (sinusoidal, 30 μT peak, 15 min) at a frequency of 9 Hz. A transient effect with maximum 40–120 min after exposure was observed. Kinetics of the per-cell-normalised ELF effects fitted well to a Gaussian distribution for all densities during exposure. A maximum value of these kinetics and a time for this maximum were strongly dependent on the cell density during exposure. These data suggest a cell-to-cell interaction during response to ELF. Both dependencies had three regions close to a plateau within the ranges of 3 × 10⁵ − 2 × 10⁷ cell/ml, 4 × 10⁷ − 2 × 10⁸ cell/ml and 4 × 10⁸–10⁹ cell/ml and two rather sharp transitions between these plateaus. The effect reached a maximum value at a density of 4 × 10⁸ cell/ml. Practically no effect was observed at the lowest density of 3 × 10⁵ cell/ml. The data suggested that the ELF effect was mainly caused by a secondary rather than a primary reaction. The filtrates from exposed cells neither induced significant AVTD changes in unexposed cells nor increased the ELF effect when were added to cells before exposure. The data did not provide evidence for significant contribution of stable chemical messengers, but some unstable compounds such as radicals could be involved in the mechanism of cell-to-cell interaction during response to ELF. The results obtained were also in accordance with a model based on an re-emission of secondary photons during resonance fluorescence. Bioelectromagnetics 19:300–309, 1998. © 1998 Wiley-Liss, Inc.