Comparative Proteomic Analysis of Methanothermobacter themautotrophicus ΔH in Pure Culture and in Co-Culture with a Butyrate-Oxidizing Bacterium

To understand the physiological basis of methanogenic archaea living on interspecies H2 transfer, the protein expression of a hydrogenotrophic methanogen, Methanothermobacter thermautotrophicus strain ΔH, was investigated in both pure culture and syntrophic coculture with an anaerobic butyrate oxidizer Syntrophothermus lipocalidus strain TGB-C1 as an H2 supplier. Comparative proteomic analysis showed that global protein expression of methanogen cells in the model coculture was substantially different from that of pure cultured cells. In brief, in syntrophic coculture, although methanogenesis-driven energy generation appeared to be maintained by shifting the pathway to the alternative methyl coenzyme M reductase isozyme I and cofactor F420-dependent process, the machinery proteins involved in carbon fixation, amino acid synthesis, and RNA/DNA metabolisms tended to be down-regulated, indicating restrained cell growth rather than vigorous proliferation. In addition, our proteome analysis revealed that α subunits of proteasome were differentially acetylated between the two culture conditions. Since the relevant modification has been suspected to regulate proteolytic activity of the proteasome, the global protein turnover rate could be controlled under syntrophic growth conditions. To our knowledge, the present study is the first report on N-acetylation of proteasome subunits in methanogenic archaea. These results clearly indicated that physiological adaptation of hydrogenotrophic methanogens to syntrophic growth is more complicated than that of hitherto proposed

The added value of advanced neuro-imaging (MR diffusion, perfusion and proton spectroscopy) in diagnosis of primary CNS lymphoma

Introduction: Primary CNS lymphoma is difficult to diagnose with conventional imaging modalities. Magnetic resonance proton spectroscopy, dynamic susceptibility contrast DSC perfusion and diffusion weighted images have been recently investigated as a problem-solving tool for evaluation of primary CNS lymphoma with favorable results.Aim of the work: To assess the value of advanced neuro-imaging (MR diffusion, perfusion and proton spectroscopy) in diagnosis of primary CNS lymphoma.Patients and methods: Five adult patients with suspected primary CNS lymphoma (as suggested by clinical or conventional imaging techniques) were prospectively studied by magnetic resonance proton spectroscopy, dynamic susceptibility contrast DSC perfusion and diffusion weighted images aiming to confirm the suspected diagnosis. The examinations were done on 1.5T machines using diffusion weighted, dynamic susceptibility contrast perfusion and chemical shift CSI imaging sequences.Results: Regarding DWI, all patients show low ADC values ranging from 0.61 to 0.67 · 10-3 mm2/s with a mean ADC value of 0.63 ±0.025(SD) 10-3 mm2/s, regarding the DSC perfusion. The max rCBV ratios are ranging from 0.23 to 1.52 with a mean ratio of 1.14 ± 0.54(SD). Regarding the MRI spectroscopy Cho/Cr ratios are ranging from 1.9 to 63 with a mean ratio of 19.16 ±26 (SD), Cho/NAA ratios are ranging from 3.7 to 50 with a mean ratio of 14.8± 19.8, NAA/Cr ratios are ranging from 0.09 to 1.6 with a mean ratio of 0.72 ±0.59, NAA/Cho ratios are ranging from 0.02 to 0.3 with a mean ratio of 0.19 ± 0.1 Lactate peak was found in three cases. Lipid peak was found in two cases. Myo inositol peak was found in one case. Conclusions: Restricted diffusion, relative hypo perfusion, increased Cho/Cr, Cho/NAA, decreased NAA/Cho, NAA/Cr and presence of lactate or lipid peaks are consistent imaging finding in CNS lymphoma.KEYWORDS Primary central nervous system lymphoma; Magnetic resonance imaging; Diffusion weighted images; Perfusion weighted images; Proton magnetic resonance spectroscop

An Overview of Ribonuclease Repertoire and RNA Processing Pathways in Archaea

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