Inhibitory Effect of Glycerin on Vibrio parahaemolyticus and Salmonella

In a study of the effect of glycerin in transport media on Vibrio parahaemolyticus and Salmonella, it was found that a concentration of 30% glycerin was highly inhibitory for V. parahaemolyticus and to a lesser degree for Salmonella. The incorporation of peptone or human feces in media did not reduce the inhibitory effect of glycerin. In media with 15% glycerin, viable counts of V. parahaemolyticus and Salmonella increased after 24 hr of incubation both in the presence and absence of feces. Due to the concurrent increase in the total bacterial count in the media containing feces, no enrichment effect was noted.     

Heritability of Eating Behavior Assessed Using the DEBQ (Dutch Eating Behavior Questionnaire) and Weight‐related Traits: The Healthy Twin Study

The heritability of eating behavior and body weight–related traits in Asian populations has not been reported. The purpose of this study was to estimate the heritability of eating behavior and the body weight–related traits of current weight and self‐reported past weight among twins and their families. Study subjects were 2,144 Korean, adult, same‐sex twins and their families at the ages between 20 and 65 years (443 monozygotic (MZ) and 124 dizygotic (DZ) twin pairs, and 1,010 individuals of their family). The Dutch Eating Behavior Questionnaire (DEBQ) was used to assess three eating behavior subscales measuring restraint, emotional eating, and external eating. A variance component approach was used to estimate heritability. After consideration of shared environmental effects and adjustment for age and sex effects, the heritability estimates ± s.e. among twins and their family members were 0.31 ± 0.036 for restraint, 0.25 ± 0.098 for emotional eating, 0.25 ± 0.060 for external eating, 0.77 ± 0.032 for measured current body weight, and 0.70 ± 0.051 for self‐reported weight at 20 years old. The three DEBQ subscales were associated with all weight related traits after adjustment for age and sex. These results suggest eating behaviors and weight‐related traits have a genetic influence, and eating behaviors are associated with obesity indexes. Our findings from Korean twin family were similar to those reported in Western populations.     

Stable ester conjugate between the Saccharomyces cerevisiae RAD6 protein and ubiquitin has no biological activity.

The RAD6 gene of Saccharomyces cerevisiae, which encodes a ubiquitin-conjugating enzyme, is required for DNA repair, DNA damage-induced mutagenesis and sporulation. To evaluate the biological relevance of the thioester adduct between RAD6 protein and ubiquitin, formed as an obligatory, transient intermediate during ubiquitin conjugation to substrates, we altered cysteine 88 in RAD6 to serine. Esterification with ubiquitin occurs at serine 88 in the mutant protein, but conjugation of ubiquitin to the test substrate histone H2A is inactivated. Phenotypically, strains harboring the rad6 Ser88 allele are indistinguishable from rad6 deletion (rad6 delta) mutant cells. These findings argue against ligation of ubiquitin at cysteine 88 acting as a functional switch of a cryptic biochemical activity in RAD6.     

Selection and proliferation of rapid growing cell lines from embryo derived cell cultures of yew tree (Taxus cuspidata Sieb. et Zucc)

Calli were induced from 300,000 embryos isolated from immature to mature stage of seeds collected on late September from 14 elite trees. When the embryos were cultured onto plastic Petri-dish containing 20 mL of modified B5 basal medium supplemented with 3% (w/v) sucrose, 500 mg/L casein hydrolysate, 250 mg/L myo-inositol, 0.5% (w/v) polyvinyl polypyrrolidon (PVPP), 2×MS vitamins, 0.5 mg/L gibberellic acid, and 10 mg/L 2,4-D after 2 weeks of culture, yellowish-white calli were immediately formed on the surfaces of embryos, and subcultured for 4 weeks in same culture medium. Because most of calli maintained for more than 3 months were revealed differences in their colors, surface texture, and growth rate, visual selection was made for first round screening. When the size of visually selected calli larger than 19 mm in their diameter were inoculated, persistent proliferation was observed. Among the plating methods tested for the selection of rapid growing cell lines at single cell and/or small cell aggregate level, 2-layer spread plating revealed as the best for single cell cloning. To enhance cell growth and maintain high rate of viability for long-term culture of yew cells in bioreactor, final cell volume less than 50% in SCV seemed to be the best. Time course study revealed that 30% of inoculum density was suitable for fed batch culture. Among the tested conditional media, the rate of 1∶2 (old medium: fresh medium) was recorded at the best for cell growth.     

Deactivation ofCandida rugosa lipase

Summary Deactivation ofCandida rugosa lipase was found to be complex. Hydrophobic interaction induced by iso-octane influenced the initial phase of deactivation, and increased the turn-over rate of the intermediate in the transition phase. After urea-treatment the structure of the last phase was not further influenced by thermal treatment, whereas that of initial phase was more sensitive to temperature change. Charge interaction was important in maintaining the structure during the deactivation, and especially anion charge might be a major factor.     

Age-related changes in oxidized proteins

We have previously described the oxidative inactivation of several key metabolic enzymes by a variety of mixed function oxidation systems. Because many of the enzymes which are inactivated have been shown by others to accumulate as inactive or less active forms during cellular aging, we have examined the levels of oxidatively modified proteins in two model systems used for studies on aging. The results show that levels of oxidatively modified proteins increase with age in circulating erythrocytes, and this change is correlated with the loss of marker enzyme activity. Our studies also show that in cultured fibroblasts from normal donors the levels of oxidatively modified proteins increase only after the age of 60. However, the levels of oxidatively modified proteins in fibroblasts from individuals with progeria or Werner's syndrome are significantly higher than age-matched controls. Moreover, treatment of glucose-6-phosphate dehydrogenase with a mixed function oxidation system leads to oxidative modification and increased heat lability of the enzyme. Taken together these results suggest that loss of functional enzyme activity and increased heat lability of enzymes during aging may be due in part to oxidative modification by mixed function oxidation systems.     

Activation of dopamine beta-monooxygenase by external and internal electron donors in resealed chromaffin granule ghosts

Membrane ghosts derived from chromaffin vesicles of bovine adrenal medullas have been used to examine the mechanism of reduction of dopamine beta-monooxygenase in its compartmentalized state. The rate of the dopamine beta-monooxygenase-catalyzed conversion of dopamine to norepinephrine is greatly stimulated by the presence of ATP, reflecting substrate hydroxylation on the ghost interior subsequent to the active transport of dopamine. We demonstrate a 2-3-fold increase in the turnover rate for ghosts resealed with 0.2-2 mM potassium ferrocyanide, conditions leading to a slight decrease in the rate of dopamine transport. These data provide the first evidence that an intravesicular pool of reductant can activate dopamine beta-monooxygenase, as required by models in which vesicular ascorbate behaves as enzyme reductant. Although there is sufficient catecholamine (endogenous plus substrate) to keep internal ferrocyanide reduced in these experiments, an additional 2-3-fold increase in turnover occurs in the presence of 0.2-2 mM ascorbate on the ghost exterior. The magnitude of this activation is found to be constant at all concentrations of internal ferrocyanide (both below and above saturation), implying that reductants on opposite sides of the membrane behave independently. Replacement of ascorbate by potassium ferrocyanide as external reductant leads to almost identical results, and we are able to rule out an inward transport of dehydroascorbate as the source of activation by external ascorbate. We conclude that external reductants are capable of reducing membrane-bound dopamine beta-monooxygenase from the exterior face of the vesicle, either by direct reduction or through a membrane-bound mediator. It appears that two viable modes for reduction of dopamine beta-monooxygenase may exist in vivo, involving the reduction of membrane-bound enzyme by cytosolic ascorbate as well as the reduction of soluble enzyme by the pool of intravesicular ascorbate present in chromaffin vesicles.     

Ultrastructure of poplar cortical cells during the transition from growing to wintering stages and vice versa

Summary Electron microscopic studies revealed that major cytological changes in the cortical cells of poplar (Populus euramericana cv. gelrica) began to occur in early September in conjunction with the metabolic transition from the growing to the wintering stage. During this transition, the cells became temporarily rich in endoplasmic reticulum, polysomes and vesicles. As the conspicuous formation of organelles progressed, the large vacuoles became smaller and filled with osmiophilic materials. Undefined organelles (protein-lipid bodies) also increased in number. From late October until March, organelles involved in protein synthesis were sparsely distributed in the cells, indicating that the number of these organelles is probably linked to the seasonal cycle of protein synthesis. In early February, after release from dormancy, fusion of vacuoles proceeded in the cells. The inclusion of organelles and a gradual decrease in the amount of osmiophilic materials in the vacuoles occurred at this stage. Subsequently, the structure of the cells continued to undergo changes to accommodate growth, which occurred in early May.