Stereochemical Control in Microbial Reduction. Part 10. Asymmetric Reduction of Alkyl 3-Methyl-2-Oxobutanoate with Immobilized Bakers' Yeast in Hexane

Esters of 3-methyl-2-oxobutanoic acid are reduced with bakers' yeast by three methods: free bakers' yeast in water, immobilized bakers' yeast in water, and immobilized bakers' yeast in hexane. Although (R)-hydroxy esters are obtained in all cases, the enantiomeric excess varies from 3% (reduction of the methyl ester with free bakers' yeast in water) to 93% (reduction of the butyl ester with immobilized bakers' yeast in hexane) depending on the structure of substrate and on the reaction conditions. The mechanism of the present stereochemical control is discussed.     

Integration of Agrobacterium T-DNA into a tobacco chromosome: Possible involvement of DNA homology between T-DNA and plant DNA

Summary We established tobacco tumour cell lines from crown galls induced by Agrobacterium. Restriction fragments containing T-DNA/plant DNA junctions were cloned from one of the cell lines, which has a single copy of the T-DNA in a unique region of its genome. We also isolated a DNA fragment that contained the integration target site from nontransformed tobacco cells. Nucleotide sequence analyses showed that the right and left breakpoints of the T-DNA mapped ca. 7.3 kb internal to the right 25 by border and ca. 350 by internal to the left border respectively. When the nucleotide sequences around these breakpoints were compared with the sequence of the target, significant homology was seen between the region adjacent to the integration target site and both external regions of the T-DNA breakpoints. In addition, a short stretch of plant DNA in the vicinity of the integration site was deleted. This deletion seems to have been promoted by homologous recombination between short repeated sequences that were present on both sides of the deleted stretch. Minor rearrangements, which included base substitutions, insertions and deletions, also took place around the integration site in the plant DNA. These results, together with previously reported results showing that in some cases sequences homologous to those in T-DNA are present in plant DNA regions adjacent to left recombinational junctions, indicate that sequence homology between the incoming T-DNA and the plant chromosomal DNA has an important function in T-DNA integration. The homology may promote close association of both termini of a T-DNA molecule on a target sequence; then TDNA may in some cases be integrated by a mechanism at least in part analogous to homologous recombination.Shogo Matsumoto is on leave from Biochemical Research Institute, Nippon Menard Cosmetic Co., Ltd, Ogaki, Gifu-ken 503, Japan     

A point mutation at the putative ATP-binding site of protein kinase C alpha abolishes the kinase activity and renders it down-regulation-insensitive. A molecular link between autophosphorylation and down-regulation

A protein kinase C alpha (PKC alpha) cDNA confers increased phorbol ester binding activity to intact cells when transiently expressed in COS cells or expressed stably in transfected rat 3Y1 fibroblasts. A point mutant (PKC alpha K----R) of PKC alpha, where Lys368 at the putative ATP-binding site is replaced with Arg, confers enhanced phorbol ester binding activity to both transiently and stably expressed COS and 3Y1 cells, respectively. Like endogenous and exogenously expressed wild type PKC alpha, the mutant PKC alpha K----R is translocated from the cytosol to the particulate fraction when cells are treated with a phorbol ester, 12-O-tetradecanoylphorbol-13-acetate (TPA). On the other hand, the mutant PKC alpha K----R is not degraded when cells are treated with TPA, making a clear contrast to wild type PKC alpha; i.e. the mutant is resistant to TPA-mediated down-regulation. The mutant lacks kinase activity as expected, as judged by autophosphorylation and by a kinase assay using a peptide substrate, although the phorbol ester binding activity remains intact. These results suggest a link between the kinase activity of PKC alpha and the sensitivity to TPA-mediated proteolytic degradation. We propose that autophosphorylation of PKC alpha is a prerequisite for proteolytic cleavage associated with the down-regulation of PKC alpha.     

Background Factors of Reflux Esophagitis and Non-Erosive Reflux Disease: A Cross-Sectional Study of 10,837 Subjects in Japan

Background

Despite the high prevalence of gastroesophageal reflux disease (GERD), its risk factors are still a subject of controversy. This is probably due to inadequate distinction between reflux esophagitis (RE) and non-erosive reflux disease (NERD), and is also due to inadequate evaluation of adjacent stomach. Our aim is therefore to define background factors of RE and NERD independently, based on the evaluation of Helicobacter pylori infection and gastric atrophy.

Methods

We analyzed 10,837 healthy Japanese subjects (6,332 men and 4,505 women, aged 20–87 years) who underwent upper gastrointestinal endoscopy. RE was diagnosed as the presence of mucosal break, and NERD was diagnosed as the presence of heartburn and/or acid regurgitation in RE-free subjects. Using GERD-free subjects as control, background factors for RE and NERD were separately analyzed using logistic regression to evaluate standardized coefficients (SC), odds ratio (OR), and p-value.

Results

Of the 10,837 study subjects, we diagnosed 733 (6.8%) as RE and 1,722 (15.9%) as NERD. For RE, male gender (SC = 0.557, OR = 1.75), HP non-infection (SC = 0.552, OR = 1.74), higher pepsinogen I/II ratio (SC = 0.496, OR = 1.64), higher BMI (SC = 0.464, OR = 1.60), alcohol drinking (SC = 0.161, OR = 1.17), older age (SC = 0.148, OR = 1.16), and smoking (SC = 0.129, OR = 1.14) are positively correlated factors. For NERD, HP infection (SC = 0.106, OR = 1.11), female gender (SC = 0.099, OR = 1.10), younger age (SC = 0.099, OR = 1.10), higher pepsinogen I/II ratio (SC = 0.099, OR = 1.10), smoking (SC = 0.080, OR = 1.08), higher BMI (SC = 0.078, OR = 1.08), and alcohol drinking (SC = 0.076, OR = 1.08) are positively correlated factors. Prevalence of RE in subjects with chronic HP infection and successful HP eradication denotes significant difference (2.3% and 8.8%; p<0.0001), whereas that of NERD shows no difference (18.2% and 20.8%; p = 0.064).

Conclusions

Significantly associated factors of NERD are considerably different from those of RE, indicating that these two disorders are pathophysiologically distinct. Eradication of Helicobacter pylori may have disadvantageous effects on RE but not on NERD.     

Potentiation by BL191 of differentiation of neuroblastoma cells induced by dibutyryl cAMP and prostaglandin E1

BL191, a newly developed phosphodiesterase inhibitor, markedly potentiated a differentiation of neuroblastoma cell clones (Neuro2a, NS-20Y, and N1E115) induced by dibutyryl cyclic adensoine 3′:5′-monophosphate(dibutyryl cAMP) and prostaglandin E₁ (PGE₁). BL191 (1 mM) inhibited DNA synthesis more strongly when used together with PGE₁ (0.5 μg/ml) and dibutyryl cAMP (0.5 mM) than papaverine (1.6 μg/ml) alone did. The inhibition rates of DNA synthesis were 72.5% for N1E-115, 75.3% for Neuro2a, and 82.5% for NS-20Y. After the treatment with BL191. PGE₁, and dibutyryl cAMP for 48 h all of three cell lines became enlarged and flattened, and extended long processes. The specific activities of choline acetyl transferase (EC 2.3.1.9) of NS-20Y and dopamine β-hydroxylase (EC 1.14.17.1) of N1E-115 increased about 3-fold as compared to the controls. The tumorigenicities of Neuro2a and N1E-115 cells were decreased, but not of NS-20Y. These data suggest the heterogenous responsiveness in neuroblastoma cells to drug treatment.     

Reactivity of Limulus amoebocyte lysate towards (1----3)-beta-D-glucans

The structure activity relationship for beta-D-glucans for the gelation of the amoebocyte lysates of the horseshoe crab (Limulus) has been investigated. beta-D-Glucans that had no (1----3) linkages induced little or no gelation. The (1----3)-beta-D-glucans curdlan (unbranched), grifolan (approximately 33% branched), schizophyllan (approximately 33% branched), lentinan (approximately 40% branched). SSG (approximately 50% branched), and OL-2 (approximately 66% branched) induced significant gelation. The optimum concentration for gelation was correlated with the content of branching. Single chain (rather than a triple helix) conformation and higher molecular weight were associated with higher reactivity.     

Alkaline Bismuth Solution as an En Bloc Stain for Formaldehyde-Glutaraldehyde Potassium Permanganate Fixed Fungal Spores

An alkaline solution of bismuth subnitrate reacted well with the cell membranes and cell walls of formaldehyde-glutaraldehyde potassium permanganate fixed Alternaria spores, demonstrating them with greater contrast than in sections stained with uranyl acetate and lead citrate. Optimal fine structure of fungal spores was obtained by en bloc staining with alkaline bismuth solution after aldehyde and permanganate fixation. The contrast of the cell organelles and cell walls was high enough in sections cut after the alkaline bismuth en bloc stain for direct ultrastructural observation. Our results indicate that the alkaline bismuth stain is useful either as an en bloc or section stain for aldehyde and permanganate fixed fungal spores.     

Involvement of histone H1.2 in apoptosis induced by DNA double-strand breaks

It is poorly understood how apoptotic signals arising from DNA damage are transmitted to mitochondria, which release apoptogenic factors into the cytoplasm that activate downstream destruction programs. Here, we identify histone H1.2 as a cytochrome c-releasing factor that appears in the cytoplasm after exposure to X-ray irradiation. While all nuclear histone H1 forms are released into the cytoplasm in a p53-dependent manner after irradiation, only H1.2, but not other H1 forms, induced cytochrome c release from isolated mitochondria in a Bak-dependent manner. Reducing H1.2 expression enhanced cellular resistance to apoptosis induced by X-ray irradiation or etoposide, but not that induced by other stimuli including TNF-alpha and UV irradiation. H1.2-deficient mice exhibited increased cellular resistance in thymocytes and the small intestine to X-ray-induced apoptosis. These results indicate that histone H1.2 plays an important role in transmitting apoptotic signals from the nucleus to the mitochondria following DNA double-strand breaks.     

Primary structures of human protein kinase C beta I and beta II differ only in their C-terminal sequences

Two types of cDNA clones encoding human protein kinase C (PKC) were isolated from a spleen cDNA library using rabbit protein kinase C beta I/beta II cDNA as a hybridization probe. Nucleotide sequence analyses of these cDNA inserts revealed complete primary structures of two distinct types of human protein kinase C beta I and beta II which differ only in their C-terminal 50 or 52 amino acid residues. It was concluded that there exist four distinct types of PKC, PKC alpha, beta I, beta II and gamma, in human as well as rabbit, and that the corresponding sequences are strictly conserved among mammalian species.