EFFECT OF INACTIVATION OF THE OXYGEN-EVOLVING SYSTEM ON THE THERMOLUMINESCENCE OF ISOLATED CHLOROPLASTS

Abstract— The effect of inactivation of water-splitting enzyme on the thermoluminescence of isolated chloroplasts was investigated. The inhibitory treatments used included Tris-washing, alkaline pH in the presence of the uncoupler gramicidin, incubation with a high concentration of magnesium ions and different chaotropic agents. It was found that inhibition of oxygen evolution resulted in the disappearance of the main thermoluminescence band at +20°C. The A band which appears at — 10°C and has been related to the S₄ state of the water-splitting enzyme (Inoue, 1981) was not considerably affected by the inhibition of oxygen evolution. The results presented here indicate that the participation of the S₄ state of water-splitting enzyme in the generation of the A band should be reinvestigated.     

Light pulse narrowing and power density increase in a laser-produced spark

The gaussian shape of a light pulse is distorted in a laser spark. A narrowing pulse appears with an amplitude enlarged by an order of magnitude due to self-focusing.     

The Preparation and Properties of Some α-Acyloxy- and α-Carbamoyloxy-Phosphonothionates

New f -acyloxy and f -carbamoyloxy derivatives of dimethyl 2,2,2-trichloroethyl-phosphonothionate have been prepared, characterized, and screened for activity against free-living soil nematodes. Several of the more easily hydrolysable esters, and also the N -methylcarbamoyl derivative, were as active as the parent pesticide, dimethyl f -hydroxy-2,2,2-trichloroethylphosphonothionate, after an induction period during which the active species is assumed to be released in vivo . It is concluded that the 2,2,2-trichloroethyl group is essential for activity in compounds of these types and that the presence of the N -methylcarbamoyl group does not in itself confer activity.     

An attempt to distinguish between the components of a mixture of isomeric fragment ions

The [C₇H₁₀NO₃]⁺ ion in the normal mass spectrum of 2-ethoxycarbonyl-5-oxo-2-pyrrolidinepropanoic acid was shown to correspond to a mixture of two isomeric structures. By decreasing the ionizing electron energy, the one containing a CH₂CH₂COOH group becomes dominant. The proportion of the concentrations of the two isomeric ions was calculated by comparing their daughter ion spectra (obtained by linked scan at constant B/E) with the analogous spectra of a derivative partially labelled by deuterium at the carboxyl and amide groups.     

Heat extraction of corn fiber hemicellulose

Water-soluble hemicellulose was extracted from corn fiber with microwave-assisted heat treatment. The effects of treatment temperature and initial pH of the aqueous extraction media were investigated regarding hemicellulose recovery and molecular mass of the isolated polysaccharides. In treatments carried out at neutral pH (simple water extraction), it has been demonstrated that hemicellulose recovery could be increased by applying higher treatment temperatures. However, the molecular weight of isolated hemicellulose gets significantly lower. For example, 10% of the raw materials' xylan was extracted at 160 degrees C and about 30% recovery was reached at 210 degrees C. However, the molecular mass of the isolated polysaccharide at 210 degrees C (5.82 x 10(4)) was about half of that measured at 160 degrees C (1.37 x 10(5)). Reducing the pH with sulfuric acid resulted in shorter polymer chains (1.7 x 10(4)) and lower hemicellulose yields (2.2%). Application of sodium hydroxide in the treatment showed that, compared with acid, considerably higher yields (11%) with longer polysaccharide chains (1.3 x 10(5)) could be obtained.     

Thermoascus aurantiacus CBHI/Cel7A production in Trichoderma reesei on alternative carbon sources

To develop functional enzymes in cellulose hydrolysis at or above 70 degrees C the cellobiohydrolase (CBHI/Cel7A) of Thermoascus aurantiacus was cloned and expressed in Trichoderma reesei Rut-C30 under the strong cbh1 promoter. Cellulase production of the parental strain and the novel strain (RF6026) was examined in submerged fermentation experiments using various carbon sources, which were lactose, Solka Floc 200 cellulose powder, and steam pretreated corn stover. An industrially feasible production medium was used containing only distiller's spent grain, KH(2)PO(4), and (NH(4))(2)SO(4). Enzyme production was followed by measurements of protein concentration, total cellulase enzyme activity (filter paper activity), beta-glucosidase activity, CBHI activity, and endogenase I (EGI) activity. The Thermoascus CBHI/Cel7A activity was taken as an indication of the heterologous gene expression under the cbh1 promoter.     

Multiple beneficial effects of resveratrol and their chemical-biochemical basis

On the basis of in vitro and in vivo investigations trans-resveratrol (RV) is a natural, concentration-dependent formaldehyde (HCHO) mobilizer, scavenger, capture and carrier molecule. The capturing and mobilization of HCHO from a given biological unit (e.g. tissue) with RV (first step) generates a chemopreventive effect. The reaction products between endogenous HCHO and RV (second step) may exert killing/inhibiting effects on pathogens and/or cancer cells. These two steps result in the double effect of RV. From the model reaction mixture of RV and HCHO in diluted formalin solution, different reaction products were detected, separated and identified. Similar reactions can be observed between RV and endogenous HCHO in plant and animal tissues as well. Capturing the HCHO molecules in model experiments with HCHO-capture molecules (in vitro conditions) the antibacterial activity of RV decreased substantially. The in vitro investigations were extended to in vivo conditions. The discovery of a quadruple immune response of plants to pathogens resulting from pretreatment with RV opens new horizons in the confirmation of the diverse beneficial effects of RV.