Actinobacillus actinomycetem-comitans: Fermentative Capabilities of 140 Strains

Fermentative capabilities of 140 strains of Actinobacillus actinomycetem-comitans were studied. Findings correspond closely with those reported previously by Heinrich and Pulverer (12 strains), and by King and Tatum (33 strains). All strains ferment glucose, levulose, and maltose and reduce nitrate to nitrite. Reactions with glycogen and starch are exceedingly diverse. Eight different biotypes have been identified on the basis of their reactions with galactose, mannitol, and xylose.     

Growth temperature affects O2 consumption rates and plasticity of respiratory flux to support shoot growth at various growth temperatures

The temperature dependence of respiration rates and their acclimation to growth temperature vary among species/ecotypes, but the details remain unclear. Here, we compared the temperature dependence of shoot O₂ consumption rates among Arabidopsis thaliana ecotypes to clarify how the temperature dependence and their acclimation to temperature differ among ecotypes, and how these differences relate to shoot growth. We examined growth analysis, temperature dependence of O₂ consumption rates, and protein amounts of the respiratory chain components in shoots of twelve ecotypes of A. thaliana grown at three different temperatures. The temperature dependence of the O₂ consumption rates were fitted to the modified Arrhenius model. The dynamic response of activation energy to measurement temperature was different among growth temperatures, suggesting that the plasticity of respiratory flux to temperatures differs among growth temperatures. The similar values of activation energy at growth temperature among ecotypes suggest that a similar process may determine the O₂ consumption rates at the growth temperature in any ecotype. These results suggest that the growth temperature affects not only the absolute rate of O₂ consumption but also the plasticity of respiratory flux in response to temperature, supporting the acclimation of shoot growth to various temperatures.     

Effects of vitamin D2-fortified shiitake mushroom on bioavailability and bone structure

Bioavailability and bone loss inhibitory effects of vitamin D₂ derived from UV-irradiated shiitake mushroom were determined in vivo. The effect of the absence of ovaries on the bioavailability of vitamin D₂ and bone structure was also investigated. Sham operated (sham) and ovariectomized (OVX) rats were divided in 3 groups according to their diets, i.e. control: only vitamin D-deficient diets; UV(X): vitamin D-deficient diets with non-irradiated mushroom powder; UV(O): vitamin D-deficient diets with irradiated mushroom powder. The obtained results showed that vitamin D₂ from shiitake mushroom was able to increase bone mineral density and trabecular bone structure of femur bone as well as its bioavailability. The absence of estrogen induced adverse effects not only on bioavailability of vitamin D₂ but also on trabecular bone. In conclusion, vitamin D₂-fortified shiitake mushroom might help postmenopausal women increase vitamin D₂ bioavailability and retard trabecular bone loss.

Abbreviations: OVX: ovariectomized; 25(OH)D: 25-hydroxyvitamin D; 1,25(OH)2D: 1,25-dihydroxyvitamin D; BMD: bone mineral density; micro-CT: micro computed tomography; RSM: response surface methodology; RP-HPLC: Reverse phase-high performance liquid chromatography; MS/MS: tandem mass spectrometry; E2: estradiol; NTx: N-terminal telopeptide of type I collagen; BV/TV: bone volume/total volume; BS/BV: bone surface/bone volume; Tb.Th: trabecular thickness; Tb.Sp: trabecular separation.     

Pax6 is misexpressed in Sox1 null lens fiber cells

Sox1 null lens fiber cells fail to elongate and have disrupted expression of gamma-crystallin. We have evaluated the expression of Sox1 and Pax6 proteins during critical stages of lens morphogenesis, with particular focus on fiber cell differentiation. While Pax6 and Sox1 are co-expressed during early stages of fiber cell differentiation, Sox1 up-regulation coincides temporally with the down-regulation of Pax6, and these proteins therefore display a striking inverse expression pattern in the lens fiber cell compartment. Furthermore, Pax6 is inappropriately expressed in the fiber cells of Sox1 null mice and the Pax6 target, alpha5 integrin, is simultaneously misexpressed. Finally, we demonstrate a genetic interaction between Sox1 and Pax6, as Sox1 heterozygosity partially rescues the diameter of Pax6(Sey) lenses by increasing the number of cells in the fiber cell compartment.     

Zebrafish as a new model for phenotype‐based screening of melanogenic regulatory compounds

Although many hypo‐pigmenting agents are currently available, the demand for novel whitening agents is increasing, in part due to the weak effectiveness and unwanted side effects of currently available compounds. To screen for novel hypo‐pigmenting agents, many methodologies such as cell culture and enzymatic assays are routinely used. However, these models have disadvantages in terms of physiological and economic relevance. In this study, we validated zebrafish as a whole‐animal model for phenotype‐based screening of melanogenic inhibitors or stimulators. We used both the well‐known melanogenic inhibitors (1‐phenyl‐2‐thiourea, arbutin, kojic acid, 2‐mercaptobenzothiazole) and newly developed small molecule compounds (haginin, YT16i). All the tested compounds produced inhibitory effects on the pigmentation of zebrafish, most likely due to their inhibitory potential on tyrosinase activity. In simultaneous in vivo toxicity tests, a newly developed melanogenic inhibitor YT16i showed massive abnormalities in terms of deformed morphologies and cardiac function. Together, these results provide a rationale in screening and evaluating the putative melanogenic regulatory compounds. We suggest that the zebrafish system is a novel alternative to mammalian models, with several advantages including the rapidity, cost‐effectiveness, and physiological relevance.     

Genetic discrimination between<Emphasis Type="Italic">Catharanthus roseus</Emphasis> cultivars by metabolic fingerprinting using<Superscript>1</Superscript>H NMR spectra of aromatic compounds

When whole cell extracts are subjected to proton nuclear magnetic resonance spectroscopy (¹H NMR), metabolite profiles are generated that contain overlapping signals of the majority of compounds within the extract. In order to determine whether pattern recognition based on the metabolite profiles of higher plants is able to genetically discriminate between plants, we analyzed leaf samples of eight cultivars ofCatharanthus roseus by¹H NMR. Hierarchical dendrograms, based on the principal component analysis of the¹H NMR total, aliphatic carbohydrate and aromatic region data, revealed possible relationships between the cultivars. The dendrogram based on the aromatic region data was in general agreement with the genetic relationships determined by conventional DNA fingerprinting methods. Secologanin and polyphenols were assigned to the signals of the¹H NMR spectra, and contributed most profoundly to the discrimination between cultivars. The overall results indicate that the genetic relationships betweenC. roseus cultivars are reflected in the differences of the aromatic compounds in the leaves.     

Sterilization effects of a TiO<Subscript>2</Subscript> photocatalytic film against a<Emphasis Type="Italic">Streptococcus mutans</Emphasis> culture

Streptococcus mutans is one of the more significant pathogens involved in the development of dental caries in humans. The purpose of this research was to design a TiO₂-coated dental instrument and to determine the bactericidal effects of the instrument onS. mutants. TiO₂ photocatalytic films were prepared by the low-pressure metal-organic chemical vapor deposition (LPMOCVD) method using titanium tetraisopropoxide (TTIP) as precursor. The photocatalytic reaction was carried out on a TiO₂-coated pyrex petri dish with an ultraviolet (UV) light emitting diode (LED) illuminator or a fluorescent lamp light source. Our data indicates that the relative survival ratio ofS. mutans when plated onto TiO₂ photocatalytic films and under exposure to UV-A light for 15 min was 0.01%. In addition, a fluorescent lamp light source also had bactericidal effects on theS. mutans plated TiO₂ photocatalytic films. These results indicate that TiO₂-coated dental materials or devices may be useful in dental treatments for the prevention of carious or enamel demineralization.