Photorespiration: stimulation of glycine decarboxylation by oxygen in tobacco leaf disks and corn leaf segments

Glycine decarboxylation, shown by us as an intermediate stepin CO₂ evolution during photorespiration, was enhanced by oxygentensions of up to 100%, whereas CO₂ evolution from glucose didnot increase when oxygen tensions were raised above 20%. Thus,we concluded that enhancement of photorespiration by oxygenis not only due to stimulation of glycolate oxidation, but alsoto stimulation of glycine decarboxylation. ¹ This work was reported at the Annual Meeting (1971) of theJapanese Society of Plant Physiologists in Okayama. ² The Okayama Tobacco Experiment Station, Japan Monopoly Corporation,Tamashima, Kurashiki, Okayama. ³ The Hatano Tobacco Experiment Station, Japan Monopoly Corporation,Naganuki, Hatano, Kanagawa. (Received October 19, 1971; )     

Studies on Lotus Seed Protease

A protease from the lotus seed (Nelumbo nucifera Gaertn) was purified by acid-treatment, ammonium sulfate-fractionation, ethylalcohol-fractionation, TEAE-cellulose-treatment and Sephadex G-100 gel-filtration.

The enzyme was purified about 870-fold and was homogeneous in electrophoretic and ultracentrifugal analyses.

Purified lotus seed protease is an acid protease with a pH optimum at 3.8 toward urea-denatured casein. It is active for casein and hemoglobin. But other proteins such as edestin, zein, lotus seed globulin and soybean casein are slightly hydrolyzed and egg albumin is hardly hydrolyzed. This enzyme is most stable at pH 4.0 below 40°C. The enzyme is not a thiol protease, and its activity was completely inhibited by potassium permanganate, remarkably inhibited by sodium dodecylsulfate and accelerated by hydrogen peroxide.     

Metabolite profiling and assessment of metabolome compartmentation of soybean leaves using non-aqueous fractionation and GC-MS analysis

In the present study, non-aqueous fractionation (NAQF) and GC-MS were used to obtain a spatially resolved view of metabolism in mature leaves of soybean (Glycine max Merr.). NAQF of lyophilized soybean leaves was performed using CCl₄-n-heptane and ultracentrifugation that yielded a gradient comprised of six fractions. Chlorophyll content, and marker enzyme activities, phosphoenolpyruvate carboxylase (PEPC) and α-mannosidase, were utilized as stroma, cytosol and vacuole markers, respectively. GC-MS analyses of each fraction resulted in the identification of around 100 different metabolites. The distribution of these identified compounds showed a decreasing order from the vacuole to cytosol to chloroplast stroma. In other words, a greater number of identified compounds were found in the vacuole when compared to the cytosol or stroma. Levels of sugars, organic acids and fatty acids showed greater relative abundances in the vacuole with 50, 55, and 50% of the respective pools. A greater relative abundance of amino acids was observed in the cytosol where 45% of the total of amino acids content was recorded. The relatively large pool of sugars and phenolic acids in the vacuole compartment implies high levels of starch metabolism and phenylpropanoid biosynthesis. The low amino acids pool, on the other hand, suggests low nitrogen accumulation in the leaves of soybean. Hierarchical cluster analysis on the most abundant metabolites revealed three clusters containing 10, 20, and 2 of the 32 selected metabolites. The data were discussed in term of NAQF and GC-MS analysis of soybean mature leaves, and also in term of distribution and compartmentation of metabolites at subcellular levels.     

Wildfire damage evaluation by merging remote sensing with a fire area simulation model in Naoshima, Kagawa, Japan

Not only wildfire damage, but the failure of post-fire forest restoration is also one of the major threats for the conservation of forest ecosystems. Therefore, it is required to estimate wildfire damaged potential and recovery capacity to orientate the management of a post-fire community. The aim of our research is to estimate the resistibility against wildfire and the post-fire regeneration capacity by merging field observation data with Terra/ASTER Level1B satellite data and a fire area simulation model (FARSITE). As a result, the resistibility against wildfire and the post-fire regeneration capacity were high in the high prior-fire normalized differential vegetation index (NDVI) areas, where the trees had been thriving. Also, after the fire, the well developed surface soil (the A horizon) provided a good environment for resprouting from unburned stumps and the rhizome. It is suggested that the thriving forests have a strong resistance against wildfire and have large regeneration capacity.     

The prereplication complex recruits XEco2 to chromatin to promote cohesin acetylation in Xenopus egg extracts

1. Download : Download high-res image (192KB)
2. Download : Download full-size image

Highlights? XEco2 loading and cohesin acetylation require pre-RC assembly but not DNA synthesis ? Two N-terminal motifs in XEco2 are essential for XEco2 loading and cohesion ? The PIP box in XEco2 contributes to cohesion ? Interaction of acetylated cohesin with DNA is stabilized after DNA replication     

Resonance Raman characterization of archaeal and bacterial Rieske protein variants with modified hydrogen bond network around the [2Fe-2S] center

The rate of quinol oxidation by cytochrome bc(1)/b(6)f complex is in part associated with the redox potential (E(m)) of its Rieske [2Fe-2S] center, for which an approximate correlation with the number of hydrogen bonds to the cluster has been proposed. Here we report comparative resonance Raman (RR) characterization of bacterial and archaeal high-potential Rieske proteins and their site-directed variants with a modified hydrogen bond network around the cluster. Major differences among their RR spectra appear to be associated in part with the presence or absence of Tyr-156 (in the Rhodobacter sphaeroides numbering) near one of the Cys ligands to the cluster. Elimination of the hydrogen bond between the terminal cysteinyl sulfur ligand (S(t)) and Tyr-Oeta (as with the Y156W variant, which has a modified histidine N(epsilon) pK(a,ox)) induces a small structural bias of the geometry of the cluster and the surrounding protein in the normal coordinate system, and significantly affects some Fe-S(b/t) stretching vibrations. This is not observed in the case of the hydrogen bond between the bridging sulfide ligand (S(b)) and Ser-Ogamma, which is weak and/or unfavorably oriented for extensive coupling with the Fe-S(b/t) stretching vibrations.     

Megakaryoblastic leukemia factor-1 gene in the susceptibility to coronary artery disease

Coronary artery disease (CAD) is based on the atherosclerosis of coronary artery and may manifest with myocardial infarction or angina pectoris. Although it is widely accepted that genetic factors are linked to CAD and several disease-related genes have been reported, only a few could be replicated suggesting that there might be some other CAD-related genes. To identify novel susceptibility loci for CAD, we used microsatellite markers in the screening and found six different candidate CAD loci. Subsequent single nucleotide polymorphism (SNP) association studies revealed an association between CAD and megakaryoblastic leukemia factor-1 gene (MKL1). The association with a promoter SNP of MKL1, ?184C > T, was found in a Japanese population and the association was replicated in another Japanese population and a Korean population. Functional analysis of the MKL1 promoter SNP suggested that the higher MKL1 expression was associated with CAD. These findings suggest that MKL1 is involved in the pathogenesis of CAD.