Spatial pattern changes in aboveground plant biomass in a grazing pasture

Using gamma distribution and spatial autocorrelation, it was demonstrated that plant biomass per unit area of a pasture grazed by cattle exhibited two kinds of spatial heterogeneity: small-scale heterogeneity caused by grazing and large-scale heterogeneity caused by topography, land aspect, etc. For each of the 10 measurement times from May to August, 100 quadrats 50cm × 50cm were arranged along a straight line 50m long in a pasture, and the plants within the quadrats were harvested at the height of 3cm above the ground surface to measure the dry weight. The data were aggregated into frequency distributions, and gamma distribution and the parameter values were estimated. This analysis showed that with the progression of grazing the amount of biomass decreased and the degree of spatial heterogeneity in biomass, measured per 0.25m², increased, and due to plant regrowth the trends were reversed. By rearranging the 100 biomass data in order of weight, it was suggested that plots with an extremely large biomass were not grazed by cattle and remained in the pasture. For the same data, variations of biomass along the straight line were divided into two parts based on the moving average: the spatial trend and the residuals which cannot be explained by the trend. In this analysis, 48–75% of the total spatial variation was explained by the trend along the straight line. Analysis using spatial autocorrelation for the actual biomass changes showed that the biomass changes within a range of about 10m on the straight line gave a positive correlation, which indicates a topographical trend in biomass. Spatial autocorrelation for residuals suggested that the spatial changes in biomass along the straight line followed a wave-like or checker-board pattern. Small-scale spatial heterogeneity in plant biomass may be caused by the uneven deposition of excreta by grazing animals, uneven use of the grassland by grazing animals, and uneven dispersal of plant seeds through faeces over the grassland. The possibility that such unevenness might accelerate energy flow in the grassland ecosystem and contribute to grassland sustainability is discussed.     

An oral Salmonella vaccine promotes the down-regulation of cell surface Toll-like receptor 4 (TLR4) and TLR2 expression in mice

A single oral immunization with the Lon-protease-deficient Salmonella enterica serovar Typhimurium (strain CS2022) induced protective immunity in mice against a subcutaneous challenge with virulent Listeria monocytogenes as well as virulent Salmonella serovar Typhimurium. The populations of cell surface Toll-like receptor 4 (TLR4) and TLR2 on peritoneal macrophages decreased at week 6 after immunization. This population decrease was not reversed after a challenge with either Salmonella or Listeria. These results suggest that oral immunization with CS2022 induced immune tolerance correlated with the down-regulation of cell surface TLR expression. This down-regulation may in part account for the development of cross-protection against a Listeria challenge by immunization with CS2022.     

Demonstration of a high affinity Ca2+ ATPase in rat liver plasma membranes

Rat liver plasma membranes contained a high affinity Ca²⁺-ATPase which had an apparent half saturation constant of 0.2 μM for calcium. The Ca²⁺-ATPase was not stimulated by adding magnesium and/or calmodulin. Conversely, the addition of these substances diminished the calcium-stimulation of the ATPase. Orthovanadate (7 nM-2 mM), mitochondrial ATPase blockers (NaN₃, KCN, dicyclohexylcarbodiimide), Na⁺, K⁺ and ouabain had no effect on the ATPase activity. The ATPase was separated from nonspecific divalent cation stimulatable ATPase (Mg²⁺-ATPase) by solubilization with Triton X-100 followed by a Sephadex G-200 column chromatography and showed an apparent molecular weight of 200,000.     

Serum-free culture of an embryonic cell line from <Emphasis Type="Italic">Bombyx mori</Emphasis> and reinforcement of susceptibility of a recombinant BmNPV by cooling

We established the first continuous cell line that uses a serum-free culture from the embryo of Bombyx mori (Lepidoptera: Bombycidae), designated as NIAS-Bm-Ke17. This cell line was serially subcultured in the SH-Ke-117 medium. The cells adhere weakly to the culture flask, and most cells have an oval shape. The cell line was subcultured 154 times, and the population doubling time is 83.67 ± 5.22 h. Random amplification of polymorphic DNA-polymerase chain reaction with a tenmar single primer for discrimination of insect cell lines recognized the NIAS-Bm-Ke1 cell line as B. mori. This cell line does not support the growth of the B. mori nuclear polyhedrosis virus (BmNPV) in the absence of the heat-inactivated hemolymph of B. mori. However, the heat-inactivated hemolymph in 1% volume of the medium supported a high level of susceptibility to BmNPV. In addition, the cooling treatment of the cells at 2.5°C also enhanced the susceptibility. We report a new serum-free culture system of the B. mori cell line for the baculovirus expression vector system.     

The Effects of Proteins and Phospholipids on the Mobility of Wheat Doughs

Penicillium strains (n=394) preserved at NBRC (the NITE Biological Resource Center) were compared as to groupings (11 species-clusters) based on phylogeny and the production of bioactive compounds. The strains in two clusters, of which P. chrysogenum and P. citrinum are representative, showed higher rates of positive strains with multi-biological activities.     

Structural Insights into the Epimerization of β-1,4-Linked Oligosaccharides Catalyzed by Cellobiose 2-Epimerase,the Sole Enzyme Epimerizing Non-anomeric Hydroxyl Groups of Unmodified Sugars

Cellobiose 2-epimerase (CE) reversibly converts d-glucose residues into d-mannose residues at the reducing end of unmodified β1,4-linked oligosaccharides, including β-1,4-mannobiose, cellobiose, and lactose. CE is responsible for conversion of β1,4-mannobiose to 4-O-β-d-mannosyl-d-glucose in mannan metabolism. However, the detailed catalytic mechanism of CE is unclear due to the lack of structural data in complex with ligands. We determined the crystal structures of halothermophile Rhodothermus marinus CE (RmCE) in complex with substrates/products or intermediate analogs, and its apo form. The structures in complex with the substrates/products indicated that the residues in the β5-β6 loop as well as those in the inner six helices form the catalytic site. Trp-322 and Trp-385 interact with reducing and non-reducing end parts of these ligands, respectively, by stacking interactions. The architecture of the catalytic site also provided insights into the mechanism of reversible epimerization. His-259 abstracts the H2 proton of the d-mannose residue at the reducing end, and consistently forms the cis-enediol intermediate by facilitated depolarization of the 2-OH group mediated by hydrogen bonding interaction with His-200. His-390 subsequently donates the proton to the C2 atom of the intermediate to form a d-glucose residue. The reverse reaction is mediated by these three histidines with the inverse roles of acid/base catalysts. The conformation of cellobiitol demonstrated that the deprotonation/reprotonation step is coupled with rotation of the C2-C3 bond of the open form of the ligand. Moreover, it is postulated that His-390 is closely related to ring opening/closure by transferring a proton between the O5 and O1 atoms of the ligand.     

Structural dynamics of dendritic spines: Molecular composition,geometry and functional regulation

The development of dendritic spines with specific geometry and membrane composition is critical for proper synaptic function. Specific spine membrane architecture, sub-spine microdomains and spine head and neck geometry allow for well-coordinated and compartmentalized signaling, disruption of which could lead to various neurological diseases. Research from neuronal cell culture, brain slices and direct in vivo imaging indicates that dendritic spine development is a dynamic process which includes transition from small dendritic filopodia through a series of structural refinements to elaborate spines of various morphologies. Despite intensive research, the precise coordination of this morphological transition, the changes in molecular composition, and the relation of spines of various morphologies to function remain a central enigma in the development of functional neuronal circuits. Here, we review research so far and aim to provide insight into the key events that drive structural change during transition from immature filopodia to fully functional spines and the relevance of spine geometry to function.