The minimal speed of traveling fronts for a diffusive Lotka-Volterra competition model

This paper concerns the minimal speed of traveling wave fronts for a two-species diffusion-competition model of the Lotka-Volterra type. An earlier paper used this model to discuss the speed of invasion of the gray squirrel by estimating the model parameters from field data, and predicted its speed by the use of a heuristic analytical argument. We discuss the conditions which assure the validity of their argument and show numerically the existence of the realistic range of parameter values for which their heuristic argument does not hold. Especially for the case of the strong interaction of two competing species compared with the intraspecific competition, we show that all parameters appearing in the system affect the minimal speed of invasion. Dedicated to the Memory of Akira Okubo     

NADH Model Reaction: Asymmetric Reduction of Non-activated Carbonyl Compounds with N-Anionized Hantzsch Ester

As model compounds for NADH coenzymes, three chiral Hantzsch ester-type dihydro-pyridines were prepared. By their use and 2,6-dimethyl-3,5-dicarbo-( — )-menthoxy-1,4-dihydropyridine that had already been prepared, asymmetric reductions of unactivated prochiral ketones were conducted under the action of alkali metal derivatives at room temperature in a non-polar solvent, and the alcohol product were obtained in a 36~80% chemical yield and 30~60% enantiomeric excess.     

Optical Rotatory Dispersion of Rotundifolone

Microbial (enzymatic) hydrolysis of (±)-O-acetyl allethrolone gave (?)-(R)-allethrolone with (+)-(S)-O-acetyl allethrolone. And microbial hydrolysis of (±)-cis and trans-2-allylcyclopentyl acetates gave the low optically active cis and trans-2-allylcyclopentanols with the acetates of their antipodes. Also, the acetates of (±)-primary alcohols with cyclopropane and cyclohexene rings: (±)-chrysanthemyl alcohol, α-cyclogeraniol, were hydrolyzed by microorganisms to give the optically active alcohols in low optical purities Further, synthesis and microbial resolution of racemic hydroxy-trimethylcyclohexanones, useful intermediate for synthesis of compounds related to carotenoids, were tried.     

A New Natural Quinone, 2-Methyl-3-II,III,VIII-hexahydromultiprenyl9-1,4-naphthoquinone

A new aryl-peptidyl amidase has been isolated from a Lactobacillus casei homogenate. Its ribosomal localization was shown by fractionation and its general properties studied after purification on Sepharose 6B and DEAE-Sephacel. The enzyme requires 1 mM Mg²⁺ for stability, while Zn²⁺, Mn²⁺, Co²⁺ and Ca²⁺ result in only partial stability. No inhibitory effects were noted after treatment with phenylmethylsulfonylfluoride or EDTA. Enzymatic activity was totally inhibited by 5mM p-hydroxymercuribenzoate; activity was restored by dithiothreitol. The only substrates hydrolyzed by this enzyme were the succinyl-L-phenylalanine-p-nitroanilide type, with a pH optimum between 6 and 7 and a Michaelis constant of 0.76 mM. No hydrolysis could be detected using proteins, peptides, amides or esterase substrates. This enzyme would thus not be an endopeptidase (E.C. 3.4.21), but would to rather be considered as belonging to the group of amidases (E.C. 3.5.1)     

Optically Active Bis-β-keto Sulfonium Ylid

Particulate alcohol dehydrogenase of acetic acid bacteria that is mainly participated in vinegar fermentation was purified to homogeneous state from Gluconobacter suboxydans IFO 12528. Solubilization of enzyme from the bacterial membrane fraction by Triton X-100 and subsequent fractionation on DEAE-Sephadex A-50 and hydroxylapatite was successful in enzyme purification. A cytochrome c-like component was tightly bound to the dehydrogenase protein and existed as an enzyme-cytochrome complex. It was also confirmed that the alcohol dehydrogenase is not a cytochrome component itself. The molecular weight of the enzyme was determined to be 150,000, and gel electrophoresis showed the presence of three subunits having a molecular weight of 85,000, 49,000 and 14,400. The smallest subunit was corresponded to the cytochrome c-like component. Ethanol was oxidized in the presence of dyes in vitro but NAD or NADP were not required as hydrogen acceptor. Unlike NAD- linked alcohol dehydrogenase in yeast or liver and other primary alcohol dehydrogenases in methanol utilizing bacteria, the enzyme from the acetic acid bacteria showed its optimum pH at fairly acidic pH.     

On the Partly Reduced Coenzyme Q Isolated from “Rhodotorula lactose” IFO 1058 and Its Relation to the Taxonomic Position

From the intact cells of “Rhodotorula lactosa” R1 (IFO 1058), a new coenzyme Q, which has a different mobility on paper chromatograms from other five naturally occurring homologs of the coenzyme Q series, was isolated and purified as a crystalline state. The chemical analyses such as UV and IR absorption spectrophotometries, and NMR and mass spectrometries revealed that the material, mp 28.7~28.9°C, was identified as a Co Q₁₀ derivative with the reduced C₅ unit in the isoprenoid side chain terminal remote from the quinone nucleus, Co Q₁₀ (H–10). The strain R 1 with such a unique coenzyme Q system is, concerning its taxonomic position, discussed in connection with other criteria.     

Enzymatic Studies on the Oxidation of Sugar and Sugar Alcohol

During the course of studies on the oxidative metabolism of d-sorbitol by acetic acid bacteria, it was found that d-sorbitol was almost quantitatively converted to 5-keto-d-fructose via l-sorbose by a certain strain of Gluconobacter suboxydans. In addition to 5-keto-d-fructose, three γ-pyrone compounds, kojic acid, 5-oxymaltol, and 3-oxykojic acid, 2-keto-l-gulonate, and several organic acids such as succinic, glycolic, and glyceric acids were confirmed in the culture filtrate of this bacterium.

• The most suitable carbon source for 5-ketofructose fermentation by Gluconobacter suboxydans Strain 1 was confirmed to be d-sorbitol or l-sorbose using growing and resting cells. d-Fructose had little effect on the formation of this dicarbonylhexose.

• The optimal pH for the formation from l-sorbose by intact cells was found to be at 4.2.

• The activity of the pentose phosphate cycle in the resting cells was calculated as 13~17 μatoms/hr/mg of dry cells by the use of the manometric techniques.

• There was no strain tested so far which could accumulate a large amount of 5- keto-d-fructose from d-sorbitol except this bacterium.

• The experimental results shown in this paper makes the prediction that a certain dehydrogenating system of l-sorbose is functional in the organism, and the metabolic pathways of d-sorbitol via l-sorbose and 5-keto-d-fructose is proposed.

     

Extracellular superoxide dismutase in tissues from obese (ob/ob) mice

We have examined the protein content and gene expression of three superoxide dismutase (SOD) isoenzymes in eight tissues from obese ob/ob mice, particularly placing the focus on extracellular-SOD (EC-SOD) in the white adipose tissue (WAT). Obesity significantly increased EC-SOD level in liver, kidney, testis, gastrocnemius muscle, WAT, brown adipose tissue (BAT), and plasma, but significantly decreased the isoenzyme level in lung. Tumor necrosis factor-α and interleukin-1β contents in WAT were significantly higher in obese mice than in lean control mice. Immunohistochemically, both WAT and BAT from obese mice could be stained deeply with anti-mouse EC-SOD antibody compared with those from lean mice. Each primary culture per se almost time-dependently enhanced EC-SOD production, and overtly expressed its mRNA. The loss of heparin-binding affinity of EC-SOD type C with high affinity for heparin occurred in kidney of obese mice. These results suggest that the physiological importance of this SOD isoenzyme in WAT may be a compensatory adaptation to oxidative stress.