Photosystem I electron transport and phosphorylation supported by electron donation to the plastoquinone region

In chloroplasts, tetramethyl-p-hydroquinone supports high rates of phosphorylation-coupled, noncyclic electron flow through Photosystem I to methylviologen. The reaction is totally sensitive to dibromothymoquinone, indicating an electron donation to the plastoquinone region of the photosynthetic chain. The uncoupled electron flow rate exceeds 1000 μequivalents per hour per mg chlorophyll. The phosphorylation efficiency ($\text{P}\text{e}{}_2$) at the optimal pH of 8 is 0.6–0.65. Presumably this ratio represents the efficiency of energy coupling in the electron transfer step plastoquinone → cytochrome f.     

Characterization of extracellular substance of Vibrio anguillarum toxic for rainbow trout and mice

An extracellular toxic substance was separated from the cell-free culture filtrate of Vibrio anguillarum (strain NCMB571). Two fractions (GI and GII + III) obtained by Sephadex G-200 chromatography following DEAE-cellulose chromatography were lethal to rainbow trout and mice. Material separated from the GI fraction by Sepharose 4B affinity chromatography (GI-A fraction) was lethal to these animals. By sodium dodecylsulfate polyacrylamide gel electrophoresis, the GI and GI-A fractions were found to be composed of components with molecular weights of 44K and 34K, and 44K, respectively. The 44K protein band was associated with carbohydrate. Peripheral vascular disorder was observed in fish and mice that died after inoculation with GI or GI-A fraction. The toxic substance was sensitive to potassium periodate but was resistant to trypsin and acetone. Heat inactivation of the toxic substance was almost complete at 100 C for 20 min and complete at 121 C for 20 min. The toxic activity was not associated with hemolytic or proteolytic activity. Homologous antitoxin completely neutralized the toxic activity.     

Quantitative measurement of endotoxin in rainbow trout (Salmo gairdneri) serum by the chromogenic substrate method

The amount of endotoxin in serum collected from normal rainbow trout ( Salmo gairdneri) and trout inoculated with viable Vibrio anguillarum or lipopolysaccharide (LPS) extracted from bacteria was determined by the chromogenic substrate method. The mean values of endotoxin in four different groups of normal rainbow trout sera ranged from 31.9 to 65.3 pg/ml. When fish were inoculated with viable bacteria (1 × 10⁸), they became septicaemic and a large amount of endotoxin (> 14 ng/ml) was detected in the sera. In fish inoculated with a smaller number of bacteria the amount of endotoxin was several times higher than that of normal fish in spite of failure of bacterial isolation. Although the endotoxin level in serum increased rapidly (> 100 ng/ml) after intraperitoneal inoculation with purified V. anguillarum LPS (540 μg), no fish died during the experiment. The high level of endotoxin in normal rainbow trout and the resistance of trout to endotoxin are in striking contrast to those of mammalian and avian species.     

Receptor recycling: liberation of glucocorticoid receptors from liver nuclei in vitro

Dynamics of the steroid receptors seems to be the consequence of receptor recycling. In the present study, as a clue to elucidate the mechanism of receptor recycling, factors which affect the rate of liberation of nuclear bound 3H-glucocorticoids were examined in vitro. Among the factors examined, NAD, NADPH, cAMP and p-nitrophenyl phosphate accelerated the liberation of radioactivity from nuclei in a temperature-dependent manner when added to the incubation mixture. The presence of a large amount of unlabeled dexamethasone (Dex) did not modify the rate of liberation. From these results, it was concluded that the metabolism of ligand bound to the receptor is not a necessary step in the liberation of receptor from nuclei. These agents did not influence the binding process of 3H-Dex-receptor complex to DNA-cellulose. Therefore the stimulation of receptor release does not seem to be mediated by reducing the binding affinity between nuclei and receptor complexes. The liberated radioactivity was eluted on a Sephadex G-100 column in the void volume and in macromolecule-unbound fractions. In both fractions, the majority of the radioactivity comigrated with authentic glucocorticoids on thin-layer chromatography.     

Intensity of photosynthesis and chlorophyll content as related to leaf age inNicotiana Sanderae hort

U r?zně starých list? v listové r??ici 90 a? 110 denních rostlin Nicotiana sanderae hort. byly sledovány rozdály v intensitě ?isté fotosynthesy a v obsahu chlorofylu (a + b). Ke stanovení intensity fotosynthesy bylo pou?ito dvou odli?ných metod, a to váhového stanovení p?ír?stku su?iny podle Barto?e, KubÍna a ?et-lÍka (1960) a gazometrického stanovení infra?erveným analyzátorem CO₂. Nejvy??í intensitu fotosynthesy i nejvy??í obsah chlorofylu (vzhledem k plo?e listové) mají mladé, ale ji? dob?e rozvinuté listy, tj. t?etí a? ?tvrté od vrcholu (prvním listem se rozumí list o plo?e asi 20 cm²). Tyto listy nazýváme ?fotosyntheticky dospělými“. Listy nejmlad?í a zejména pak listy star?í mají intensitu fotosynthesy i obsah chlorofylu ni??í; u nejstar?ích list? je intensita fotosynthesy prakticky nulová. Intensita fotosynthesy i obsah chlorofylu se během vývoje mění: jejich momentální rozdíly u list? v genetické spirále jsou z?ejmě shodné s jejich změnami v ontogenesi listu. Pokles intensity fotosynthesy p?i stárnutí list? je rychlej?í ne? pokles obsahu chlorofylu. P?i ur?itém obsahu chlorofylu (tj. asi 2,25 a? 2,45 mg/dm²) klesá intensita ?isté fotosynthesy k nule. Intensita fotosynthesy je v lineárním vztahu k mno?ství chlorofylu (p?i p?epo?tu na plo?nou jednotku), a to nezávisle na poloze listu v genetické spirále. Obě pou?ité metody ke stanovení intensity fotosynthesy poskytly obdobné výsledky.     

Structure of Major Surface Determinants and DNA Diagnosis of Pneumocystis carinii

Pneumocystis carinii is a pathogen which, causes fatal pneumonia in patients with the acquired immune deficiency syndrome (AIDS). To facilitate the basic study of P. carinii , we have analyzed its major surface proteins by both immunochemical and biochemical methods. The major protein components of both cysts and trophozoites are a group of proteins called "P115" with apparent masses of 105–120 kd. It includes 6 isoelcclric variants. A monoclonal antibody raised against cysts recognizes all 6 variants and reacts with epitopes located in the cell wall indicating that P115 is an immunorcactive surface component. The isoelectric variants contain identical or closely related protein components and they are mannose-rich glycoproteins. The isoelectric variation may be due primarily to differences in glycosylation. The majority of sera from humans with diagnosed pneumocystosis that were tested reacted strongly with the P115 proteins. To develop probes for DNA diagnosis and to facilitate molecular studies, a genomic DNA library of P. carinii has been constructed. Some of these clones were used for DNA hybridization analysis of rat and human lungs.     

镉引起小麦苗逆境乙烯的产生及其和镉的吸收分布的关系

溶液培养小麦幼苗转移至含Cd~(2 )的营养液中,根系乙烯产生较快地增加,约在12h达高峰,然后下降;ACC含量亦呈先升后降的趋势。未和Cd~(2 )溶液直接接触的地上部乙烯亦增加,至36h达高峰,此后急剧下降,而ACG和 MAGC含量持续上升。地上部乙烯的增加,主要是由通过根系运往地上部的镉直接作用的结果,不是根部合成ACG运往地上部后再产生的。电镜观察表明,地上部乙烯产生和ACC含量变化的时间进程,可以与镉进入叶细胞内的部位及其对细胞膜和细胞器的影响相联系。     

Proposal of leukotoxin, 9,10-epoxy-12-octadecenoate, as a burn toxin

It is postulated that toxic substances (burn toxin) synthesized in burned skin are transferred into general circulation and cause multiple organ failure. We found a highly cytotoxic substance, leukotoxin, a linoleate epoxide, exists in burned skin. Leukotoxin, as the name indicates, was synthesized by leukocytes from linoleate as a substrate. The aim of this study is to evaluate the possibility of leukotoxin as a burn toxin. We studied plasma leukotoxin level of four patients with extensive burns (over 50% of body surface area) and examined coagulation studies in these patients. We detected considerable amounts of leukotoxin (11.4 nmol/ml-37.0 nmol/ml) in all patients. Leukotoxin was not detected in the control subjects. Pulmonary edema, cardiac failure, and coagulation abnormalities were found in these patients. Exogeneously administered leukotoxin induced similar pathological conditions in experimental animals to those observed in patients with extensive burns. Hence, it is concluded that leukotoxin is a responsible substance as a burn toxin.     

固定化虫荧光素酶光纤传感器

固定化虫荧光素酶光纤传感器蔡谨,王顺光,杨歧生,吉鑫松（浙江大学化工系生化教研室,杭州３１００２７;中国科学院上海生物化学研究所,２０００３１）关键词虫荧光素酶,ＡＴＰ,固定化酶,光纤生物传感器ＡＴＰ是生物体内极为重要的能量物质。如何准确快速地定量Ａ...