Phylogenetic identification and substrate uptake patterns of sulfate-reducing bacteria inhabiting an oxic-anoxic sewer biofilm determined by combining microautoradiography and fluorescent in situ hybridization.

We simultaneously determined the phylogenetic identification and substrate uptake patterns of sulfate-reducing bacteria (SRB) inhabiting a sewer biofilm with oxygen, nitrate, or sulfate as an electron acceptor by combining microautoradiography and fluorescent in situ hybridization (MAR-FISH) with family- and genus-specific 16S rRNA probes. The MAR-FISH analysis revealed that Desulfobulbus hybridized with probe 660 was a dominant SRB subgroup in this sewer biofilm, accounting for 23% of the total SRB. Approximately 9 and 27% of Desulfobulbus cells detected with probe 660 could take up [(14)C]propionate with oxygen and nitrate, respectively, as an electron acceptor, which might explain the high abundance of this species in various oxic environments. Furthermore, more than 40% of Desulfobulbus cells incorporated acetate under anoxic conditions. SRB were also numerically important members of H(2)-utilizing and (14)CO(2)-fixing microbial populations in this sewer biofilm, accounting for roughly 42% of total H(2)-utilizing bacteria hybridized with probe EUB338. A comparative 16S ribosomal DNA analysis revealed that two SRB populations, related to the Desulfomicrobium hypogeium and the Desulfovibrio desulfuricans MB lineages, were found to be important H(2) utilizers in this biofilm. The substrate uptake characteristics of different phylogenetic SRB subgroups were compared with the characteristics described to date. These results provide further insight into the correlation between the 16S rRNA phylogenetic diversity and the physiological diversity of SRB populations inhabiting sewer biofilms.     

Conformer equilibria of triostin A and its conformer-specific interaction with nucleic acid bases

A quinoxaline antibiotic triostin A has a bicyclic octadepsipeptide structure. Proton and carbon-13 nmr spectra showed the presence of two symmetrical conformations favoring polar and nonpolar solvents, respectively. They interconvert slowly on the nmr time scale, and this slow interconversion is due to the cooperative effects of the presence of the quinoxaline ring and the N-methyl peptide bonds. Reversal of the chirality of the disulfide bond as the origin of the slow exchange was excluded by the presence of two conformers for S-benzyltriostin A. Conformer 2, which favors the polar solvent, can form hydrogen-bonded complexes with purine nucleoside derivatives in organic solvents, but conformer 1 does not. The binding sites were elucidated and a mode of interaction with DNA proposed.     

Oxidation of lysozyme by iodine: isolation of an inactive product and its conversion to an oxindolealanine-lysozyme

Reaction of lysozyme with a half-molar amount of iodine at pH 5.5 gives, in 50% yield (based on iodine), an enzymatically-inactive singly-oxidized derivative. This intermediate can be converted to an oxindole-lysozyme. Analysis showed no modification other than two-electron oxidation of one tryptophan. Substrate analogs prevent the oxidative inactivation. Reaction of crystalline lysozyme with iodine gives the same inactive product found in solution.     

Relationships between higher‐level functional capacity and dental health behaviors in community‐dwelling older adults

doi: 10.1111/j.1741‐2358.2012.00654.x Relationships between higher‐level functional capacity and dental health behaviors in community‐dwelling older adults Objective: The aim of the present study was to elucidate relationships between higher‐level functional capacity and dental health behaviours in community‐dwelling older adults. Background: In ageing society, it is necessary to promote oral health in the elderly, because good oral health is a significant contributing factor to good general health. Higher‐level functional capacity has been considered a crucial factor for successful independent living in the elderly. We hypothesised that functional capacity is a significant indicator of dental health behaviours. Methods: Three hundred and thirty‐eight adults aged 65 years or older were enrolled in this study. Higher‐level functional capacity was evaluated using the Tokyo Metropolitan Institute of Gerontology Index of Competence (TMIG‐index). Univariate and multivariate models were constructed with dental health behaviours, such as regular visits to a dentist, brushing frequency and use of extra cleaning devices, as the dependent variable, and the total TMIG‐index score and its subcategory scores as the principal independent variable. Results: Univariate logistic regression analysis demonstrated a significant correlation between low TMIG‐index and ‘intellectual activity’ subcategory scores to lack of regular visits to a dentist and not using extra cleaning devices. Using a multivariate model, significant relationships remained after adjusting for a number of variables including demographics, medical status, lifestyle and number of remaining teeth. Conclusion: Intellectual activity of higher‐level functional capacity may be an accurate indicator of dental health behaviours in community‐dwelling older adults. Intellectual activity should be taken into consideration to effectively promote oral health behaviours and oral hygiene in elderly persons living independently.     

Antifungal Activity and Molecular Orbital Energies of Aldehyde Compounds from Oils of Higher Plants

Mechanisms of antifungal actions of cinnamaldehyde, citral, perillaldehyde and citronellal were investigated. The growth inhibitions by the aldehydes were reduced or abolished in the presence of cysteine or glutathione in some cases, indicating that the inhibitions were mainly due to reactions of the aldehydes with SH groups involved in the fungal growth. In other cases, the SH compounds were ineffective on the inhibitory actions of the aldehydes. By calculating energies of molecular orbitals of the aldehydes, it was found that the antifungal activity was related to the energy of the lowest empty molecular orbital, i.e., the lower the energy, the higher is the antifungal activity. The energy values of the molecular orbitals indicate that the aldehydes except citronellal are good electron acceptors. It was further demonstrated, by studies of difference spectra, that cinnamaldehyde, citral and perillaldehyde are capable of forming charge transfer complexes with tryptophan, a good electron donor. These results strongly suggest that the antifungal actions of the aldehydes are possibly due to their abilities to form charge transfer complexes with electron donors in addition to their reactivity with SH groups.     

Nature of the binding site around and reactivity of histidine-15 in lysozyme

Bromoacetamide derivatives having n-alkyl substituents (BrCH2CONH(CH2)nH, 1-n) and carboxyalkyl substituents (BrCH2CONH(CH2)nCOOH, 2-n) react with His-15 in lysozyme exclusively at N epsilon 2 at pH 5.5 and 40 degree C. Kinetic studies suggest that lysozyme has a small hydrophobic pocket that binds these reagents in the vicinity of His-15.