Improvement of operational stapility of yeast lipase by chemical treatment

Summary Treatment with dithiothreitol stabilized the esterification activity of Celite-adsorbed lipase fromCandida cylindracea in organic solvent systems. The treated lipase showed the stereoselectivity in the esterification of menthol with 5-phenylvaleric acid as in the case of the native enzyme.     

Transfer Agent of Immunity

Using erythrocytes as antigen particles, number of antibody-forming cells was enumerated by immunocytoadehesion technique, in which formation of rosette was shown to be inhibited by anti-mouse immunoglobulin sera. This number increased in vitro after treatment of spleen cells of mice for 60 min with RNA fraction extracted from spleen of mice immunized with erythrocytes used in the enumeration, and incubation of cells for 12 hr at 37 C. Response of cells treated with immune RNA fraction was immunologically specific and was inhibited by puromycin or cycloheximide. The activity of immune RNA capable of converting nonimmune cells to antibody-forming cells was shown to be sensitive to ribonucleases but resistant to deoxyribonuclease and proteolytic enzyme.     

Identification of the active protein in rice bran protein having an inhibitory activity of cholesterol micellar solubility

In our previous study, rice bran protein (RBP) inhibited cholesterol micellar solubility in vitro and decreased serum cholesterol level in rats. In the present study, RBP was separated and purified by size-exclusion chromatography and reversed-phase chromatography. The active protein of RBP related to cholesterol micellar solubility was identified as lectin and non-specific lipid-transfer protein 1 using MALDI-TOF mass spectrometry analysis.     

Involvement of protein kinase Cδ in induction of apoptosis by cationic liposomes in macrophage-like RAW264.7 cells

We have recently demonstrated that reactive oxygen species (ROS) play an important role in RAW264.7 cell apoptosis induced by cationic liposomes composed of stearylamine (SA-liposomes). In this study, we investigated whether protein kinase Cδ PKCδ) is involved in apoptosis induced by cationic liposomes. Tyrosine phosphorylation, nuclear localization, and cleavage of PKCδ were observed following the treatment of cells with SA-liposomes, suggesting that SA-liposomes activate PKCδ. Rottlerin, a specific inhibitor of PKCδ, inhibited ROS generation and also suppressed apoptosis. Cell surface proteoglycans may contribute to PKCδ activation by SA-liposomes. These findings suggest that PKCδ is strongly associated with apoptosis induced by SA-liposomes.     

Asymmetric reduction of alkyl aryl ketones in the binding domain of bovine serum albumin

The asymmetric reduction of alkyl aryl ketones with sodium borohydride (NaBH₄) or sodium cyanoborohydride (NaBH₃CN) in the presence of bovine serum albumin (BSA) was studied. The asymmetric induction in the product alcohols was largely dependent on the BSA concentration and the pH value of the buffer solution. The maximum optical yields obtained ranged over 14–78%, varying with the alkyl and aryl substituents, using ca. $\text{1}\text{3}$ molar eq of BSA to the ketone and at pH > 9. With two exceptions, the predominant enantiomer had the R configuration in 13 ketones investigated.     

Differential population responses of native and alien rodents to an invasive predator,habitat alteration and plant masting

Invasive species and anthropogenic habitat alteration are major drivers of biodiversity loss. When multiple invasive species occupy different trophic levels, removing an invasive predator might cause unexpected outcomes owing to complex interactions among native and non-native prey. Moreover, external factors such as habitat alteration and resource availability can affect such dynamics. We hypothesized that native and non-native prey respond differently to an invasive predator, habitat alteration and bottom-up effects. To test the hypothesis, we used Bayesian state-space modelling to analyse 8-year data on the spatio-temporal patterns of two endemic rat species and the non-native black rat in response to the continual removal of the invasive small Indian mongoose on Amami Island, Japan. Despite low reproductive potentials, the endemic rats recovered better after mongoose removal than did the black rat. The endemic species appeared to be vulnerable to predation by mongooses, whose eradication increased the abundances of the endemic rats, but not of the black rat. Habitat alteration increased the black rat''s carrying capacity, but decreased those of the endemic species. We propose that spatio-temporal monitoring data from eradication programmes will clarify the underlying ecological impacts of land-use change and invasive species, and will be useful for future habitat management.     

Sexual process in eight-spored ascus-forming yeast, Schizosaccharomyces japonicus I. Culture medium for the synchronous sexual process

The sexual process of Schizosaccharomyces japonicus consistsof sexual flocculation, zygote formation, eight-spored ascusformation and liberation of spores from the ascus. The culturemedium in which this sexual process took place synchronouslywas prepared. For the completion of the sexual process, glucosewas essential and inorganic salts and vitamins were also required.Elimination of the nitrogen source stimulated the rate of sporeformation. The temporal relationship among the sexual eventswas also elucidated: sexual flocculation, zygote formation,ascus formation and spore liberation occurred at 4, 7, 13 and20 hr, respectively, after transfer to the medium for the synchronoussexual process. (Received May 11, 1978; )