Methanosarcina mazei and related mesophilic archaea are the only organisms fermenting acetate, methylamines, and methanol to methane and carbon dioxide, contributing significantly to greenhouse gas production. The biochemistry of these metabolic processes is well studied, and genome sequences are available, yet little is known about the overall transcriptional organization and the noncoding regions representing 25% of the 4.01-Mb genome of M. mazei. We present a genome-wide analysis of transcription start sites (TSS) in M. mazei grown under different nitrogen availabilities. Pyrosequencing-based differential analysis of primary vs. processed 5 ends of transcripts discovered 876 TSS across the M. mazei genome. Unlike in other archaea, in which leaderless mRNAs are prevalent, the majority of the detected mRNAs in M. mazei carry long untranslated 5 regions. Our experimental data predict a total of 208 small RNA (sRNA) candidates, mostly from intergenic regions but also antisense to 5 and 3 regions of mRNAs. In addition, 40 new small mRNAs with ORFs of <30 aa were identified, some of which might have dual functions as mRNA and regulatory sRNA. We confirmed differential expression of several sRNA genes in response to nitrogen availability. Inspection of their promoter regions revealed a unique conserved sequence motif associated with nitrogen-responsive regulation, which might serve as a regulator binding site upstream of the common IIB recognition element. Strikingly, several sRNAs antisense to mRNAs encoding transposases indicate nitrogen-dependent transposition events. This global TSS map in archaea will facilitate a better understanding of transcriptional and posttranscriptional control in the third domain of life.Methanosarcina mazei strain Gö1 is a representative methaneproducing archaeon of ecologic significance because of its role in biogenic methane production in various anaerobic habitats on Earth (1). The genome sequences of M. mazei and its close relatives Methanosarcina acetivorans and Methanosarcina barkeri have recently become available and have revealed an unexpected low proportion of coding region (74.2% in M. acetivorans, 75.15% in M. mazei, and 79.2% in M. barkeri) (2-4). The biochemical basis of methanogenesis has been analyzed in considerable detail (5, 6). In contrast, little is known about global regulatory networks that ensure survival in periods of nutrient starvation or stress in this important group of archaea. More than 50 predicted transcriptional regulators were annotated in the genome of M. mazei. Strikingly, most of them seem to be closely related to bacterial proteins (2), whereas the basic components of the archaeal transcription and translation machineries generally are more similar to those of eukaryotes (7). A recent genetic study (8) discovered the first global transcriptional regulator of M. mazei, the nitrogen regulator NrpR, which was experimentally demonstrated to globally repress transcription of nitrogen fixation and assimilation genes in response to the nitrogen source.Bes...

OCT features in NMSC are identified, but AK and BCC cannot be differentiated. OCT diagnosis is less accurate than clinical diagnosis, but high accuracy in distinguishing lesions from normal skin, crucial for delineating tumor borders, was obtained.

OCT appears more precise and less biased than HFUS for thickness measurement in AK and BCC lesions < 2 mm, but both OCT and especially HFUS tended to overestimate tumour thickness.

The conformation of the 20-residue antibiotic ionophore alamethicin in macroscopically oriented phospholipid bilayers has been studied using (15)N solid-state nuclear magnetic resonance (NMR) spectroscopy in combination with molecular modeling and molecular dynamics simulations. Differently (15)N-labeled variants of alamethicin and an analog with three of the alpha-amino-isobutyric acid residues replaced by alanines have been investigated to establish experimental structural constraints and determine the orientation of alamethicin in hydrated phospholipid (dimyristoylphosphatidylcholine) bilayers and to investigate the potential for a major kink in the region of the central Pro(14) residue. From the anisotropic (15)N chemical shifts and (1)H-(15)N dipolar couplings determined for alamethicin with (15)N-labeling on the Ala(6), Val(9), and Val(15) residues and incorporated into phospholipid bilayer with a peptide:lipid molar ratio of 1:8, we deduce that alamethicin has a largely linear alpha-helical structure spanning the membrane with the molecular axis tilted by 10-20 degrees relative to the bilayer normal. In particular, we find compatibility with a straight alpha-helix tilted by 17 degrees and a slightly kinked molecular dynamics structure tilted by 11 degrees relative to the bilayer normal. In contrast, the structural constraints derived by solid-state NMR appear not to be compatible with any of several model structures crossing the membrane with vanishing tilt angle or the earlier reported x-ray diffraction structure (Fox and Richards, Nature. 300:325-330, 1982). The solid-state NMR-compatible structures may support the formation of a left-handed and parallel multimeric ion channel.

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