Oxidative damage to proteins in yeast cells exposed to adaptive levels of H(2)O(2)

When yeast cells are exposed to sublethal concentrations of oxidants, they adapt to tolerate subsequent lethal treatments. Here, we show that this adaptation involves tolerance of oxidative damage, rather than protection of cellular constituents. o- and m-tyrosine levels are used as a sensitive measure of protein oxidative damage and we show that such damage accumulates in yeast cells exposed to H(2)O(2) at low adaptive levels. Glutathione represents one of the main cellular protections against free radical attack and has a role in adaptation to oxidative stress. Yeast mutants defective in glutathione metabolism are shown to accumulate significant levels of o- and m-tyrosine during normal aerobic growth conditions.     

Phenotypic Characterization of Polysaccharidases Produced by Four Prevotella Type Strains

Four ruminal Prevotella type strains, P. ruminicola JCM8958^T, P. bryantii B₁4^T, P. albensis M384^T, and P. brevis ATCC19188^T, were characterized for polysaccharide-degrading activities with the reducing sugar release assay and zymogram analyses. Carboxymethylcellulase, xylanase, and polygalacturonate (PG)-degrading enzyme activities were determined in cultures grown on oat spelt xylan, xylose, arabinose, cellobiose, and glucose as sole growth substrates. P. ruminicola and P. albensis showed carboxymethylcellulase induction patterns. When xylan was supplied as a sole growth substrate, xylanase activities produced by P. bryantii and P. albensis were at least 18- and 11-fold higher, respectively, than during growth on other carbohydrates, suggesting that the regulation of the xylanases was highly specific to xylan. All strains constitutively produced PG-degrading enzymes. The corresponding activity of P. bryantii was more than 40-fold higher than in other strains. Zymogram analyses routinely detected the presence of high-molecular-weight (100–170 kDa) polysaccharide-degrading enzymes in ruminal Prevotella. Characteristics of the polysaccharide-degrading activities showed diversity of ruminal Prevotella species. Received: 29 November 1999 / Accepted: 1 February 2000     

Coprobacillus catenaformis gen. nov., sp. nov., a new genus and species isolated from human feces

Three strains of Eubacterium-like isolates from human feces were characterized by biochemical tests and 16S rDNA analysis. The phenotypic characteristics of the three strains resembled those of the genus Collinsella transferred from the genus Eubacterium recently. However, Eubacterium-like strains were phylogenetically members of the Clostridium subphylum of gram-positive bacteria, and these showed a specific phylogenetic association with Clostridium ramosum and C. spiroforme. C. ramosum and C. spiroforme are gram-positive, anaerobic, spore-forming bacteria that belong to the genus Clostridium, and the G + C contents are 26.0 and 27.4 mol%, respectively. However, the three Eubacterium-like strains had G + C contents of 32.1 to 33.1 mol% and were non-spore-forming rods. Based on phenotypic characteristics, we can differentiate these species, and furthermore, a 16S rDNA sequence divergence of greater than 9% with a new related genus, Coprobacillus, is proposed for the three strains, with one species, Coprobacillus catenaformis. The type strain of C. catenaformis is JCM 10604T.     

Characterization of Leuconostoc species isolated from vacuum-packaged ham

Thirty-six isolates of Leuconostoc spp. were isolated from yellow spots that occurred on the surface of vacuum-packaged ham. All isolates were Gram-positive, catalase-negative cocci that produced gas from glucose and formed more than 90% of their lactate as D(-) isomer. These isolates could grow at 4 degrees C but not above 30 degrees C and most strains produced yellow spots on the ham. The isolates were divided into three groups by sugar fermentation patterns. Representative strains from three groups showed intergroup DNA homology values of above 88.8%, showing that these groups were composed of a single species. This organism was positioned at a separate branch in the genus Leuconostoc on the phylogenetic tree based on 16S rRNA sequences, which was assigned to Leuconostoc gelidum on the basis of DNA-DNA relatedness.     

Desert perennials as plant and soil indicators in Eastern Arabia

Soils of different Eastern Arabian vegetation types, dominated by five desert perennials have been analysed for their texture, salinity and surface hardness. The vegetation types were analysed for plant species richness and composition. Special emphasis was given to Abu Dhabi's widespread terrestrial perennials Cyperus conglomeratus Rottb., Haloxylon salicornicum (Moq.) Bge., Pennisetum divisum (Gmel.) Henr., Seidlitzia rosmarinus Ehrenb. ex Bge. and Zygophyllum mandavillei Hadidi. The results show some important relationships between soils and plants. C. conglomeratus indicates the lowest soil salinity levels and the finest texture. P. divisum indicates the highest species richness and S. rosmarinus indicates the lowest species richness. Z. mandavillei indicates the highest salinity levels, the largest soil particle size, and the hardest soil surfaces.     

Rapid detection and quantification of five periodontopathic bacteria by real-time PCR

The quantity of periodontopathic bacteria in plaque samples is an important determinant for understanding the etiologic role of bacteria. The real-time PCR method was used to detect and quantify periodontopathic bacteria, such as Actinobacillus actinomycetemcomitans, Bacteroides forsythus, Porphyromonas gingivalis, Treponema denticola, and Treponema socranskii, in saliva and subgingival plaque samples. There was good agreement between the results of conventional PCR and real-time PCR methods. Using the LightCycler system we were able to determine the amount of periodontopathic bacteria within an hour. The real-time PCR method was linear for samples containing from 10(3) to more than 10(8) cells (r2 = 0.999). The application of the real-time PCR method should be useful in the rapid detection and quantification of periodontopathic bacteria in clinical samples.     

Sample size and sampling error in geometric morphometric studies of size and shape

Geometric morphometric studies are increasingly becoming common in systematics and palaeontology. The samples in such studies are often small, due to the paucity of material available for analysis. However, very few studies have tried to assess the impact of sampling error on analytical results. Here, this issue is addressed empirically using repeated randomized selection experiments to build progressively smaller samples from an original dataset of ∼400 vervet monkey (Cercopithecus aethiops) skulls. Size and shape parameters (including mean size and shape, size and shape variances, angles of allometric trajectories) that are commonly used in geometric morphometric studies, are estimated first in the original sample and then in the random subsamples. Estimates are then compared to give an indication of what is the minimum desirable sample size for each parameter. Mean size, standard deviation of size and variance of shape are found to be fairly accurate even in relatively small samples. In contrast, mean shapes and angles between static allometric trajectories are strongly affected by sampling error. If confirmed in other groups, our findings may have substantial implications for studies of morphological variation in present and fossil species. By performing rarefaction analyses like those presented in our study, morphometricians can be easily provided with important clues on how a simple but crucial factor like sample size can alter results of their studies.     

Carotenoids in ripe green and in autumn senescing leaves of apple tree: I - Qualitative composition of free carotenoids,xanthophyll esters and fatty acids of esters

Abstract

By different chemical, spectral and chromatographic procedures seven carotenoids, two carotenes (α- and β-carotene) and five free xanthophylls (violaxanthin, lutein, antheraxanthin, zeaxanthin and neoxanthin) have been isolated and identified in green apple leaves. In autumn senescing leaves, besides the above seven carotenoids, the occurrence of at least seven xanthophyll esters has also been proved. Four esters, violaxanthin mono- and diester and lutein mono- and diester, (≥90% of total esters) and a minor component, neoxanthin triester, have been identified. Another minor component is most probably a monoester of antheraxanthin; the seventh, present in traces, has not been identified.

The fatty acids combined with the above xanthophyll esters have been analysed by gas-chromatography. The unusual presence of low molecular weight fatty acids, C7-C11, has been registered (1,5-8% of the total); caprilic and capric acids have been identified. Lauric acid with three minor homologous (2-7% and myristic acid (9-15%) are also present. The major component, palmitic acid, with palmitoleic and two other minor components, reaches 36-44%. In addition a remarkable presence of oleic acid (12-26%) has been observed together with stearic (8-10%), linolenic (5-6%), arachidic (0,7-2,5%) and linolenic-gadoleic acids (2,5-9,3%).