Production and Characteristics of Raw-Potato-Starch-Digesting α-Amylase from Bacillus subtilis 65

A newly isolated bacterium, identified as Bacillus subtilis 65, was found to produce raw-starch-digesting α-amylase. The electrophoretically homogeneous preparation of enzyme (molecular weight, 68,000) digested and solubilized raw corn starch to glucose and maltose with small amounts of maltooligosaccharides ranging from maltotriose to maltoheptaose. This enzyme was different from other amylases and could digest raw potato starch almost as fast as it could corn starch, but it showed no adsorbability onto any kind of raw starch at any pH. The mixed preparation with Endomycopsis glucoamylase synergistically digested raw potato starch to glucose at 30°C. The raw-potato-starch-digesting α-amylase showed strong digestibility to small substrates, which hydrolyzed maltotriose to maltose and glucose, and hydrolyzed p-nitrophenyl maltoside to p-nitrophenol and maltose, which is different from the capability of bacterial liquefying α-amylase.     

Synergistic actions of disulfide-reducing agents on 1-methyladenine-induced oocyte maturation in starfish

Several disulfide-reducing agents, such as dithiothreitol, 2,3-dimercapto-1-propanol, cysteine ethyl ester, and cysteine methyl ester enhanced the effectiveness of 1-methyladenine (1-MeAde) to induce oocyte maturation in the starfish Asterina pectinifera. This enhancement occurred at relatively low concentrations at which these agents by themselves were ineffective in inducing oocyte maturation. The agents caused a marked (about twofold) increase in specific [1-3H]MeAde binding. The binding increased directly in relation to the potency of the agents in enhancing 1-MeAde action. Scatchard analysis indicated that dithiothreitol increased the Bmax without affecting the affinity of 1-MeAde binding. These results strongly suggest that disulfide-reducing agents enhance the maturational action of 1-MeAde by increasing the number of 1-MeAde binding sites in oocyte cortices.     

Branching-diffusion model for the formation of distributional patterns in populations

A continuous time branching-diffusion process model is presented to describe the development of spatial distributional patterns of a biological population. In the model each unit moves independently following diffusion processes on a plane, and multiplies or goes extinct at random times. Standard methods for measuring the degree of aggregation used in field ecology are applied to this model population. Kuno's C _Aindex using quadrat sampling is calculated, and the dependence of the index on time, quadrat size, initial density, and diffusion and branching rules, is discussed. Pielou's index based on distance measurement is evaluated by the solution of a nonlinear partial differential equation. Both methods show that continuous-time branching-diffusion processes produce a contagious spatial pattern; as in a discrete-time model studied by Iwasa and Teramoto (1977).     

Serum LH,progesterone and estradiol-17β levels throughout the ovarian cycle,during the early stage of pregnancy and after the parturition and the abortion in the common marmoset,Callithrix jacchus

In the ovarian cycle of common marmosets, serum progesterone began to increase at two to three days after estradiol-17β or LH surge, attained a peak of 25–70 ng/ml and then declined to a level of under 2 ng/ml before the ensuing rise in estradiol-17β and LH. Serum estradiol-17β increased to 700–5,500 pg/ml during the luteal phase, synchronizing with progesterone. It is suggested that the corpus luteum secreted estradiol-17β as well as progesterone. The cycle length as determined from the interval between successive LH surges was approximately 28 days. During the luteal phase, the levels of progesterone and estradiol-17β were higher than in Old World monkeys and women, but marmosets were not accompanied by any clinical symptoms due to excessive progesterone and estradiol-17β. This suggests that such unresponsiveness to progesterone and estradiol-17β in marmosets reflects the small amount of estradiol-17β receptor and presumably also the lower function of the post receptor system. Recovery of the post-partum ovarian cycle in two marmosets differed from that observed in Old World monkeys and women. The first LH surge was found on the ninth and tenth day after parturition and the first ovulation led to the next pregnancy. This suggests that the suckling stimulus of newborns in the common marmoset does not cause any delay in recovery of the ovarian cycle. In three cases of abortion, the recovery of the ovarian cycle was almost the same as that in the case of normal parturition: the first LH surge appeared on the 10th, 14th, and 34th day after abortion.     

Efficient Expression of Peroxidatic Activity of Catalase in the Coupled System with Glucose Oxidase—a model of Yeast Peroxisomes

Catalase functioned exclusively to degrade hydrogen peroxide in a reaction mixture containing methanol and hydrogen peroxide, while, when the enzyme was coupled with glucose oxidase, successful conversion of methanol to formaldehyde occurred at the optimized ratio of glucose oxidase to catalase: activity, 1.0 × 10 ^-3; number of molecules, 1.3; protein content, 1. These values in the coupled system were very similar to the ratio of alcohol oxidase to catalase in peroxisomes, one of the subcellular organelles from a methanol-assimilating yeast, Kloeckera sp. 2201, in which these enzymes were coupled to metabolize methanol efficiently. The presence of the optimum ratio in the coupled system in vitro was confirmed by the kinetic analysis of the expression of the peroxidatic activity of catalase coupled with glucose oxidase. Construction of the immobilized system of the coupled enzymes at the optimum ratio demonstrated that the oxidation of methanol through the peroxidatic function of catalase could be continuously and stably operated, the results indicating the usefulness of the system as a model of yeast peroxisomes. Thus, the coupled reaction with glucose oxidase brought out the latent function of catalase, which could not be expected in the system including only catalase.     

Solution properties of synthetic polypeptides. VI. Helix-coil transition of poly-N5-(3-hydroxypropyl)-L-glutamine

A new procedure for evaluating u and σ characterizing σ-helix-forming polypeptides in solution was derived from Nagai's theory for the helix–coil transition of such polymers. Here u is the activity for helix formation from random coil, and σ is the helix initiation parameter. The necessary data are the helical content f_N at fixed solvent and temperature as a function of N, where N is the degree of polymerization of the polypeptide sample. Such data were obtained from ORD measurements on a number of fractionated samples of poly-N⁵-(3-hydroxypropyl)-L -glutamine (PHPG) in mixtures of water and methanol covering the complete range of composition and at various termperatures (5–40°C). When analyzed in terms of the proposed procedure, they yielded values of σ which were in the range (3.2 ± 0.6) × 10^?4, substantially independent of solvent composition and temperature. These values were much larger than those obtained recently for σ of poly(β-benzyl-L -aspartate) in m-cresol and in a mixture of chloroform and DCA. The data for [η] and s₀ (limiting sedimentation coefficient) as functions of molecular weight indicated that the molecular shape of PHPG in pure methanol is essentially rodlike, whereas that in pure water is not entirely randomly coiled but rather may be regarded as an interrupted helix. These indications were consistent with the results from ORD measurements. When plotted against the corresponding values of f_N, the values of [η] and [s₀] for PHPG in mixtures of water and methanol of various compositions and temperatures formed smooth composite curves, and we attributed these phenomena to the fact that σ of PHPG was nearly constant under these solvent conditions. Here [s₀] stands for a reduced limiting sedimentation coefficient which is equal to the inverse friction factor of the solute molecule.     

Solution properties of synthetic polypeptides. 18. Helix-coil transition of poly-N5-(2-hydroxyethyl)L-glutamine

The helix–coil transition of poly-N⁵-(2-hydroxyethyl)L -glutamine (PHEG) in aqueous isopropanol was examined by means of optical rotatory dispersion (ORD) and intrinsic viscosity [η] measurements. The Zimm–Bragg parameters σ and s for the transition were determined from the ORD data as a function of molecular weight. It was found that the transition was characterized by a relatively low cooperativity; the values of \documentclass{article}\pagestyle{empty}\begin{document}$ \sqrt \sigma $\end{document} were in the range from 0.039 to 0.066, depending on the solvent composition. These σ values are much larger than those reported for other polypeptide–solvent systems. The transition enthalpy was negative and its magnitude varied with the solvent composition, with a maximum of 620 cal/mol at 40 wt% isopropanol. The curve of [η] versus helical content for a high-molecular-weight sample exhibited a very broad minimum, and this behavior was attributed to the low cooperativity of the transition.     

Spatial pattern formation of prey-predator populations

Summary Formation of a non-uniform spatial distribution pattern of prey and predator populations in a heterogeneous environment is mathematically investigated. Both populations are distributed in linearly connected compartments. Furthermore it is assumed that only the predator species (animal) can randomly diffuse across the boundaries but the prey species (plant) are confined in each compartment. When the prey-predator relation is given by a simple Volterra type interaction it is known that the system cannot establish a non-uniform stationary distribution in a homogeneous environment. However, in a heterogeneous environment, it can be analytically shown by constructing a Lyapunov function that the system asymptotically and globally tends to a non-uniform stationary distribution. Thus, the populations are stabilized by the heterogeneity of environment.     

Characterization of Microbial Community Structure in the Surface Sediment of Osaka Bay, Japan, by Phospholipid Fatty Acid Analysis

Twenty-eight sediment samples collected from Osaka Bay, Japan, were analyzed for phospholipid ester-linked fatty acids (PLFA) to determine regional differences in microbial community structure of the bay. The abundance of three major groups of C₁₀ to C₁₉ PLFA (saturated, branched, and monounsaturated PLFA), which accounted for 84 to 97% of the total PLFA, indicated the predominance of prokaryotes in the sediment. The distribution of six clusters obtained by similarity analysis in the bay revealed a marked regional distribution in the PLFA profiles. Total PLFA concentrations (0.56 to 2.97 μg/g [dry weight] of the sediment) in sediments also showed marked variation among the stations, with higher concentrations of total PLFA in the central part of the bay. The biomass, calculated on the basis of total PLFA concentration, ranged from 0.25 × 10⁸ to 1.35 × 10⁸ cells per g (dry weight) of the sediment. The relative dominance of microbial groups in sediments was described by using the reported bacterial biomarker fatty acids. Very small amounts of the characteristic PLFA of microeukaryotes in sediments indicated the restricted distribution of microeukaryotes. By examining the distribution of clusters and groups of microorganisms in the bay, there were two characteristics of the distribution pattern: (i) the predominance of anaerobic bacteria and gram-positive prokaryotes, characterized by the high proportions of branched PLFA in the eastern and northeastern sides of the bay, where the reported concentrations of pollutants were also high, and (ii) the predominance of aerobic prokaryotes and eukaryotes, except for a few stations, in the western and southwestern sides of the bay, as evidenced by the large amounts of monounsaturated PLFA. Such significant regional differences in microbial community structure of the bay indicate shifts in microbial community structure.