Phylogenetic analysis of a novel sulfate-reducing magnetic bacterium, RS-1, demonstrates its membership of the δ-Proteobacteria

Abstract Most of the 16S ribosomal RNA gene of a sulfate-reducing magnetic bacterium, RS-1, was sequenced, and phylogenetic analysis was carried out. The results suggest that RS-1 is a member of the δ-Proteobacteria, and it appears to represent a new genus. RS-1 is the first bacterium reported outside the α-Proteobacteria that contains magnetite inclusions. RS-1 therefore disrupts the correlation between the α-Proteobacteria and possession of magnetite inclusions, and that between the δ-Proteobacteria and possession of greigite inclusions. The existence of RS-1 also suggests that intracellular magnetite biomineralization is of multiple evolutionary origins.     

Inhibition of swarming motility of Pseudomonas aeruginosa by branched-chain fatty acids.

Pseudomonas aeruginosa is capable of moving by swimming, swarming, and twitching motilities. In this study, we investigated the effects of fatty acids on Pseudomonas aeruginosa PAO1 motilities. A branched-chain fatty acid (BCFA)--12-methyltetradecanoic acid (anteiso-C15:0)--has slightly repressed flagella-driven swimming motility and completely inhibited a more complex type of surface motility, i.e. swarming, at a concentration of 10 microg mL(-1). In contrast, anteiso-C15:0 exhibited no effect on pili-mediated twitching motility. Other BCFAs and unsaturated fatty acids tested in this study showed similar inhibitory effects on swarming motility, although the level of inhibition differed between these fatty acids. These fatty acids caused no significant growth inhibition in liquid cultures. Straight-chain saturated fatty acids such as palmitic acid were less effective in swarming inhibition. The wetness of the PAO1 colony was significantly reduced by the addition of anteiso-C15:0; however, the production of rhamnolipids as a surface-active agent was not affected by the fatty acid. In addition to motility repression, anteiso-C15:0 caused 31% repression of biofilm formation by PAO1, suggesting that BCFA could affect the multiple cellular activities of Pseudomonas aeruginosa.     

A Portable Lipid Bilayer System for Environmental Sensing with a Transmembrane Protein

This paper describes a portable measurement system for current signals of an ion channel that is composed of a planar lipid bilayer. A stable and reproducible lipid bilayer is formed in outdoor environments by using a droplet contact method with a micropipette. Using this system, we demonstrated that the single-channel recording of a transmembrane protein (alpha-hemolysin) was achieved in the field at a high-altitude (∼3623 m). This system would be broadly applicable for obtaining environmental measurements using membrane proteins as a highly sensitive sensor.     

Isolation and characterization of a cDNA encoding mitochondrial chaperonin 10 from Arabidopsis thaliana by functional complementation of an Escherichia coli groES mutant

Chaperonin (Cpn) is one of the molecular chaperones. Cpn10 is a co-factor of Cpn60, which regulates Cpn60-mediated protein folding. It is known that Cpn10 is located in mitochondria and chloroplasts in plant cells. The Escherichia coli homologue of Cpn10 is called GroES. A cDNA for the Cpn10 homologue was isolated from Arabidopsis thaliana by functional complementation of the E. coli groES mutant. The cDNA was 647 bp long and encoded a polypeptide of 98 amino acids. The deduced amino acid sequence showed approximately 50% identity to mammalian mitochondrial Cpn10s and 30% identity to GroES. A Northern blot analysis revealed that the mRNA for the Cpn10 homologue was expressed uniformly in various organs and was markedly induced by heat-shock treatment. The Cpn10 homologue was constitutively expressed in transgenic tobaccos. Immunogold and immunoblot analyses following the subcellular fractionation of leaves from transgenic tobaccos revealed that the Cpn10 homologue was localized in mitochondria and accumulated at a high level in transgenic tobaccos.     

Synthesis of fisetin and 2′,4′,6′-trihydroxydihyrochalcone 4′-O-β-neohesperidoside based on site-selective deacetylation and deoxygenation

Fisetin and 2′,4′,6′-trihydroxydihyrochalcone 4′-O-β-neohesperidoside were synthesized from commercially available quercetin and naringin in five steps. The key steps are site-selective deacetylation and subsequent deoxygenation. The target molecules were obtained in 37% and 23% yields from the starting materials, respectively.     

Sleep-related factors associated with industrial accidents among factory workers and sleep hygiene education intervention

Sleep and Biological Rhythms - This study was conducted to investigate the association between industrial accidents and sleep-related parameters in factory workers, and to examine the effectiveness...     

Densification of cyanobacteria from a lake leading to production of β‐cyclocitral and related volatile organic compounds and species change

The purpose of the present study was to demonstrate that the lysis with the blue color formation was caused by densification of the cyanobacteria, and related events of the species change in the cyanobacteria were induced by the resulting volatile organic compounds (VOCs), particularly β‐cyclocitral. In order to obtain a high cell density of cyanobacteria in the laboratory, a concentration technique (graduated cylinder method) using the buoyancy of the gas vesicles was successfully used. The collected scum contained mainly Dolichospermum spp. and Microcystis, and the dispersed cyanobacteria were concentrated in the surface layer after several hours and the concentration ratio became approximately 10. The concentrated cyanobacteria were gradually lysed, while some of the cyanobacteria sank to the bottom, which finally died and disappeared. This method has the additional advantage that it is possible to visualize the entire lysis process. During the concentration process, β‐cyclocitral and its oxidation products together with β‐ionone were significantly detected. Because β‐cyclocitral was easily oxidized to the corresponding carboxylic acid, the pH of the water in the graduated cylinder decreased to approximately 6. Under favorable conditions, lysis with the blue color from phycocyanin could be observed due to the acid stress. Overall, the results of the present study were consistent with the hypothesis that VOCs were produced when the cyanobacteria are highly dense, and that the lysis with the blue color formation occurs due to the higher density.     

cDNA cloning and differential gene expression of three catalases in pumpkin

Three cDNA clones (cat1, cat2, cat3) for catalase (EC 1.11.1.6) were isolated from a cDNA library of pumpkin (Cucurbita sp.) cotyledons. In northern blotting using the cDNA-specific probe, the cat1 mRNA levels were high in seeds and early seedlings of pumpkin. The expression pattern of cat1 was similar to that of malate synthase, a characteristic enzyme of glyoxysomes. These data suggest that cat1 might encode a catalase associated with glyoxysomal functions. Furthermore, immunocytochemical analysis using cat1-specific anti-peptide antibody directly showed that cat1 encoding catalase is located in glyoxysomes. The cat2 mRNA was present at high levels in green cotyledons, mature leaf, stem and green hypocotyl of light-grown pumpkin plant, and correlated with chlorophyll content in the tissues. The tissue-specific expression of cat2 had a strong resemblance to that of glycolate oxidase, a characteristic enzyme of leaf peroxisomes. During germination of pumpkin seeds, cat2 mRNA levels increased in response to light, although the increase in cat2 mRNA by light was less than that of glycolate oxidase. cat3 mRNA was abundant in green cotyledons, etiolated cotyledons, green hypocotyl and root, but not in young leaf. cat3 mRNA expression was not dependent on light, but was constitutive in mature tissues. Interestingly, cat1 mRNA levels increased during senescence of pumpkin cotyledons, whereas cat2 and cat3 mRNAs disappeared during senescence, suggesting that cat1 encoding catalase may be involved in the senescence process. Thus, in pumpkin, three catalase genes are differentially regulated and may exhibit different functions.     

The influence of floral symmetry and pollination systems on flower size variation

We compared the amount of variation in flower size between autogamous and insect-pollinated species to examine the hypothesis that pollinator-mediated selection stabilizes flower size in plant populations. One would expect the flower size variation to be larger in selfing species that are less affected by pollinator-mediated stabilizing selection than in insect-pollinated species. The results of phylogenetic comparisons between autogamous and insect-pollinated flowers supported the pollinator-mediated stabilizing selection hypothesis, although the non-phylogenetic comparison did not. According to our results, we discuss the factors influencing the flower size variation.