A methylaspartate cycle in haloarchaea

Access to novel ecological niches often requires adaptation of metabolic pathways to cope with new environments. For conversion to cellular building blocks, many substrates enter central carbon metabolism via acetyl-coenzyme A (acetyl-CoA). Until now, only two such pathways have been identified: the glyoxylate cycle and the ethylmalonyl-CoA pathway. Prokaryotes in the haloarchaea use a third pathway by which acetyl-CoA is oxidized to glyoxylate via the key intermediate methylaspartate. Glyoxylate condensation with another acetyl-CoA molecule yields malate, the final assimilation product. This cycle combines reactions that originally belonged to different metabolic processes in different groups of prokaryotes, which suggests lateral gene transfer and evolutionary tinkering of acetate assimilation. Moreover, it requires elevated intracellular glutamate concentrations, as well as coupling carbon assimilation with nitrogen metabolism.     

Heat-induced aggregation of whey proteins: comparison of cheese WPC with acid WPC and relevance of mineral composition

Heat-induced aggregation of whey proteins in solutions made from two commercial whey protein concentrates (WPCs), one derived from mineral acid whey (acid WPC) and the other from cheese whey (cheese WPC), was studied using polyacrylamide gel electrophoresis (PAGE), size exclusion chromatography (SEC), and transmission electron microscopy (TEM). Heat treatment (75 degrees C) of acid WPC solutions (12.0%, w/w, pH 6.9) resulted in formation of relatively small "soluble" aggregates that were predominantly disulfide-linked. By contrast, heat treatment of the cheese WPC solutions (under the same conditions) caused formation of relatively large aggregates, containing high proportions of aggregates linked by noncovalent associations. The rate of aggregation of both beta-lactoglobulin and alpha-lactalbumin at 75 degrees C, measured as the loss of native proteins by PAGE, was higher in the cheese WPC solution than in the acid WPC solution. Cross dialysis of the two WPC solutions resulted in alteration of the mineral composition of each WPC solution and reversing their heat-induced aggregation behavior. The results demonstrated that the mineral composition is very important in controlling the aggregation behavior of WPC products.     

Isolation and identification of antifungal and antialgal alkaloids from Haplophyllum sieversii

Bioassay-guided fractionation of the hexane/ethyl acetate/water (H/EtOAc/H2O) crude extract of the aerial parts of Haplophyllum sieversii was performed because of preliminary screening data that indicated the presence of growth inhibitory components against Colletotrichum fragariae, Colletotrichum gloeosporioides, and Colletotrichum acutatum. Fractionation was directed using bioautographical methods resulting in the isolation of the bioactive alkaloids flindersine, anhydroevoxine, haplamine, and a lignan eudesmin. These four compounds were evaluated for activity against C. fragariae, C. gloeosporioides, C. acutatum, Botrytis cinerea, Fusarium oxysporum, and Phomopsis obscurans in a dose-response growth-inhibitory bioassay at 50.0, 100.0, and 150.0 microM. Of the four compounds tested, flindersine demonstrated the highest level of antifungal activity. Additionally, flindersine, eudesmin, and haplamine were screened against the freshwater phytoplanktons Oscillatoria perornata, Oscillatoria agardhii, Selenastrum capricornutum, and Pseudanabaena sp. (strain LW397). Haplamine demonstrated selective inhibition against the odor-producing cyanobacterium O. perornata compared to the activity against the green alga S. capricornutum, with lowest observed effect concentration values of 1.0 and 10.0 microM, respectively.     

Oxidative stability of conjugated linoleic acid isomers

Conjugated linoleic acids (CLAs) have been shown to be a strong anticarcinogen in a number of animal models. Our previous study demonstrated that CLA as a whole was extremely unstable in air. The present study was undertaken further to examine the oxidative stability of individual CLA isomers using the combination of gas-liquid chromatography (GLC) and silver ion high-performance liquid chromatography (Ag-HPLC). It was found that CLA as a whole oxidized rapidly and more than 80% was degraded within 110 h in air at 50 degrees C. Four c,c-CLA isomers were most unstable followed by four c,t-CLA isomers. In contrast, four t,t-CLA isomers were relatively stable under the same experimental conditions. Both the oxygen consumption and the GLC analysis revealed that 200 ppm jasmine green tea catechins (GTCs) exhibited protection to CLA and were even stronger than 200 ppm butylated hydroxytoluene (BHT) when added to either CLA or canola oil containing 10% CLA. The present study emphasized that oxidative unstability of CLA should not be overlooked although CLA has many biological effects.     

雌花黄瓜植株的花芽生长和败育与温度的关系

为了探索雌花黄瓜植株的花芽生长和败育与温度的关系,作者1981年8月初,将雌花黄瓜的栽培品种“Farbio”的种子播于装有泥炭的花盆里,并且在21℃下发了芽。10天后,大致按70株一组将秧苗分成了3组,放在植物生长箱内,置于15℃、21℃和27℃恒温条件下,给以自然光照。在27℃条件下生长29天移植后再转移到21℃的玻璃温室,生长在21℃和15℃     

兽用抗蠕虫药剂型研究进展

近十多年来,随着化学工业的发展,抗寄生虫药品的品种、数量不断地增加,质量也大大提高、目前,抗寄生虫药的发展趋向是:要求具备广谱、高效、低毒,无致癌、致畸胎、致突变“三致”作用,此外,还应投药方便,适口性好,剂量小,无残毒残留和不易产生耐药性等。但是,目前兽医临床上常使用的抗寄生虫药,除少数几种溶于水外,大部分都不溶于水,应用起来不够方便,     

世界兽药（动物保健品）工业协会介绍

世界兽药（动物保健品）工业协会介绍徐士新（中国兽药监察所北京，１０００８１）世界兽药（动物保健品）工业协会（ＣｏｎｆｅｄｅｒａｔｉｏｎＭｏｎｄｉａｌｅｄｅＩ＇ＩｎｄｕｓｔｒｉｅｄｅｌａＳａｎｔｅＡｎｉｍａｌｅ简称ＣＯＭＩＳＡ）是世界兽药工业，亦称动物...