The Processing of a 57-kDa Precursor Peptide to Subunits of Rice Glutelin

The processing of a 57-kDa peptide into 37- and 22-kDa subunitsof glutelin, a major storage protein of rice, was confirmedby the immunological compatibility between the precursor andglutelin subunits. The 57-kDa peptide reacted with the antiseraraised against purified 37-kDa and 22-kDa subunits of glutelin.The processing was further confirmed by alteration of an invivo protein synthesis by monensin, a sodium ionophore whichinhibits the intracellular transport of secretory and membraneproteins. Infusion of monensin into developing rice grains resultedin suppressed formation of mature glutelin subunits with concomitantaccumulation of the 57-kDa peptide. The present results indicatethat both subunits of rice glutelin were produced by post-translationalcleavage of the 57-kDa peptide. (Received July 9, 1986; Accepted October 1, 1986)     

Sucrose-Induced Accumulation of beta-Amylase Occurs Concomitant with the Accumulation of Starch and Sporamin in Leaf-Petiole Cuttings of Sweet Potato

β-Amylase of sweet potato (Ipomoea batatas L.), which constitutes about 5% of the total soluble protein of the tuberous root, is absent or is present in only small amounts in organs other than the tuberous roots of the normal, field-grown plants. However, when leaf-petiole cuttings from such plants were supplied with a solution that contained sucrose, the accumulation of β-amylase was induced in both leaf and petiole portions of the explants. The sucrose-induced accumulation of β-amylase in leaf-petiole cuttings occurred concomitant with the accumulation of starch and of sporamin, the most abundant storage protein of the tuberous root. The accumulation of β-amylase, of sporamin and of starch in the petioles showed similar dependence on the concentration of sucrose, and a 6% solution of sucrose gave the highest levels of induction when assayed after 7 days of treatment. The induction of mRNAs for β-amylase and sporamin in the petiole could be detected after 6 hours of treatment with sucrose, and the accumulation of β-amylase and sporamin polypeptides, as well as that of starch, continued for a further 3 weeks. In addition to sucrose, glucose or fructose, but not mannitol or sorbitol, also induced the accumulation of β-amylase and sporamin, suggesting that metabolic effects of sucrose are important in the mechanism of this induction. Treatment of leaf-petiole cuttings with water under continuous light, but not in darkness, also caused the accumulation of small amounts of these components in the petioles, probably as a result of the endogenous supply of sucrose by photosynthesis. These results suggest that the expression of the gene for β-amylase is under metabolic control which is coupled with the expression of sink function of cells in the sweet potato.     

Dark Anaerobic Inactivation of Photosynthetic Oxygen Evolution by Chlamydomonas reinhardtii

When intact cells of Chlamydomonas reinhardtii were anaerobicallyincubated in the dark, rapid inactivation of oxygen evolutionwith benzoquinone as the Hill oxidant occurred. Measurementsof electron transport using thylakoids isolated after anaerobictreatment showed that the inactivation occurred at, or before,the secondary electron acceptor of PS II, whereas PS I activitywas largely unaffected. In addition, after anaerobic treatmentfluorescence transients measured with no addition or with dibromomethylisopropylbenzoquinonepresent were virtually the same as those obtained with DCMUpresent. When 10 mM NaHCO₃ was added to inactivated cells, partof the oxygen evolution capacity was restored rapidly. However,almost complete recovery (within 20 to 25 min) required theaddition of oxygen as well. This recovery was not light-dependentand was faster in the presence of 1 mM KCN. We suggest thatthe in activation of benzoquinone-dependent oxygen evolutionwas due to both bicarbonate depletion and reduction of the plastoquinonepool. ¹Present address: Institute of Molecular Biophysics, FloridaState University, Tallahassee, Florida 32306, U.S.A. (Received January 17, 1984; Accepted February 25, 1984)     

Mitochondrial genome of a Japanese placozoan

Placozoans are marine invertebrates found in tropical and subtropical waters. Their body plan is among the simplest of free-living animals. The present study determined the mitochondrial genome sequence of a placozoan collected on the coast of Shirahama, Wakayama, Honshu, Japan, and compared it with those of Trichoplax adhaerens from the Red Sea and of three strains from the Caribbean Sea. The sequences of mitochondrial respiratory chain of the Japanese placozoan genes are very similar to those of the BZ49 strain from the Caribbean Sea. However, there are distinct differences in gene arrangement, such as the location of two open reading frames. This Japanese placozoan is therefore distinguishable from the other strains. Based on current knowledge of placozoan 16S diversity our 'Shirahama' strain most likely represents the H15 lineage, known from the Philippines. In the mitochondrial genome of placozoans, substitution rates are slower than in bilaterians, whereas the rate of rearrangements is faster.     

Biochemical properties and pathophysiological roles of cytosolic phospholipase A2s

Phospholipase A(2) (PLA(2)) (EC 3.1.1.4) catalyzes hydrolysis of the sn-2 ester bond of glycerophospholipids. The enzyme is essential for the production of two classes of lipid mediators, fatty acid metabolites and lysophospholipid-related lipids, as well as being involved in the remodeling of membrane phospholipids. Among many mammalian PLA(2)s, cytosolic PLA(2)alpha (cPLA(2)alpha) plays a critical role in various physiological and pathophysiological conditions through generating lipid mediators. Here, we summarize the in vivo significance of cPLA(2)alpha, revealed from the phenotypes of cPLA(2)alpha-null mice, and properties of newly discovered cPLA(2) family enzymes. We also briefly introduce a quantitative lipidomics strategy using liquid chromatography-mass spectrometry, a powerful tool for the comprehensive analysis of lipid mediators.     

Monitor of the myostatin autocrine action during differentiation of embryonic chicken myoblasts into myotubes: effect of IGF-I

Molecular and Cellular Biochemistry - Viral inflammation and infection of mesothelial cells (MC) are a major problem in several organ systems including pleura, pericardium and peritoneum. Toll-like...     

Real-time fluorescence monitoring of GSK3β-catalyzed phosphoryation by use of a BODIPY-based Zn(II)–Dpa chemosensor

We developed a new fluorescence assay system for GSK3β-catalyzed kinase reaction using the BODIPY-based fluorescent chemosensor. This system exploits the selective sensing property of the chemosensor for a (i, i+4) bis-phosphorylated peptide, which allows us to conveniently detect the phosphorylation reaction with a fluorescence increase in a real-time fashion.     

Chestnut pellicle for the recovery of gold

Recovery of Au(III) from hydrochloric acid medium by using crosslinked chestnut pellicle (CCP) gel was studied. Strong selectivity was observed for Au(III) showing negligible affinity for other precious metals and some base metal ions tested. The adsorption isotherm study exhibited the maximum loading capacity of the gel as high as 10.6 mol or about 2.1 kg gold per kg dry weight of gel. The reduction of Au(III) ion to elemental form during adsorption process is expected to be the reason of high selectivity and high capacity for Au(III). Kinetic studies at various temperatures confirm an endothermic adsorption process following the pseudo-first order rate law.