THE STRUCTURAL AND STORAGE CARBOHYDRATES OF SACCHAROMYCES CEREVISIAE: CHANGES DURING FERMENTATION OF WORT AND A ROLE FOR GLYCOGEN CATABOLISM IN LIPID BIOSYNTHESIS

Detailed analysis of the structural and storage carbohydrates of Saccharomyces cerevisiae (NCYC 240) during wort fermentation showed that there were no significant changes in the amounts of trehalose or alkali-soluble glycogen. However, glucan and mannan individually increased from ca4% of the yeast dry weight at pitching to ca6% during the first 3–17 h of fermentation, butthen declined to the former level. In the first 2 h of fermentation, prior to yeast multiplication, acid-soluble glycogen was rapidly dissimilated from ca 40% to ca 6% of the yeast dry weight. During this period of oxygen uptake, wort sugars were not removed by the yeast. Glycogen, therefore, was the sole source of metabolic energy for lipid resynthesis and hexose transport appeared to require the formation of a component membrane. During the latter phase of fermentation when the yeast was not growing but expending energy for maintenance of cellular functions, glycogen reserves were slowly depleted; after a period of prolonged anaerobic storage, the content of glycogen fell well below that which was initially present in the pitching yeast.     

Contribution of cathepsins B,L and D to muscle protein profiles correlated with texture in rainbow trout (Oncorhynchus mykiss)

Post-mortem softening of fish tissue often results in low yield and decreased product quality. In this study, proteolytic profiles of trout stored 5 days on ice were obtained by SDS–PAGE. The link between protein band intensities and firmness of trout fillets was examined through a correlation study. In parallel, trout extracts were incubated with cathepsin B, cathepsin L and cathepsin D, alone or in combination, in order to evaluate the effect of each cathepsin on the texture-related proteins. Proteins from both myofibrillar (α-actinin, actin, MLC1, MLC2, and N-terminal 70 kDa MHC fragment) and sarcoplasmic (glycogen phosphorylase, creatine kinase, and TPI) fractions correlated closely with firmness. Cathepsins D, B and L affected, respectively, 10, 9 and 4 out of the 17 protein bands correlating with firmness, and most changes induced by cathepsin D were unfavourable to firmness. This implies that cathepsin D is likely to be involved in textural change of trout, due to breakdown of the muscle structure.     

强化生物除磷系统胞内聚合物测定方法优化

为优化强化生物除磷系统胞内PHA、糖原以及多聚磷酸盐颗粒的测定方法,采用色谱与化学分析相结合的方法进行研究.其中,PHA的测定采用气相色谱法,糖原的测定采用稀盐酸消解加葡萄糖试剂盒法,多聚磷酸盐采用过硫酸钾氧化和钼锑抗光度法,经过方法优化得出4%酸化甲醇消解20h是提高PHA回收量的最佳条件;糖原在0.6mol/LHCl条件下消解5h提取量最大,临床中的葡萄糖氧化酶法试剂盒可以应用到本实验中;在120℃下氧化30min条件下多聚磷酸盐颗粒可以最大回收.经过加标回收实验等对这3个方法进行精密度、准确度分析,结果显示,在这3个条件下的3种方法都具有很高的精密度或准确度,而且简单易行,适合实验室及生产实践中的应用.     

静电场对力竭性运动后的大鼠的组化及生化的影响

通过对长期施以５ 种不同场强的训练型大鼠在急性力竭性训练后即刻的血清尿素氮水平的测试,以及对上述训练后的即刻、１２ ｈ 、２４ ｈ 的心肌糖元测定结果的研究分析,探讨了静电场对力竭训练后的大鼠的疲劳恢复的可行性及静电作用对消除机体疲劳的影响。     

生物除磷系统聚糖菌的代谢机理及菌群结构

针对聚糖菌的富集引起强化生物除磷系统(EBPR)运行不稳定问题,开展聚糖菌代谢机理、微生物形态和菌群结构研究,以了解EBPR工艺的微生物原理.聚糖菌在厌氧环境中分解体内的糖原以获得能量来摄取外界环境中的短链脂肪酸,因而在厌氧反应阶段与聚磷菌形成对有机底物的竞争矛盾.尤其当聚糖菌在某些未明确因素下取得竞争优势后,系统中的聚磷菌将逐渐被淘汰替换或成为非优势菌种,从而导致EBPR除磷功能的完全丧失.研究表明,进水基质类型、进水P/C比、pH、温度以及亚硝酸盐等因素决定着聚糖菌和聚磷菌的竞争优势,并在特定阈值内引起EBPR系统聚糖菌的富集而使除磷功能丧失.     

强化生物除磷动态模型研究进展

概述了国内外强化生物除磷(EBPR)动态模型的研究进展,主要介绍了其中较成熟的ASM模型和代谢模型,并对这两类模型中的代表模型的运用条件、优缺点进行了评述.在此基础上指出了目前EBPR模型发展中存在的共性问题,并提出:代谢/ASM复合模型和杂交模型是EBPR模型未来发展的方向,但完善的EBPR模型的建立最终还要依赖于对EBPR代谢机理的透彻研究.     

Inhibitory mode of N-phenyl-4-pyrazolo[1,5-b] pyridazin-3-ylpyrimidin-2-amine series derivatives against GSK-3: molecular docking and 3D-QSAR analyses

Glycogen synthase kinase 3 (GSK-3) inhibition is an important research topic because of its wide range of associated health implications. The interaction mode of a series of N-phenyl-4-pyrazolo[1,5-b]pyridazin-3-ylpyrimidin-2-amine compounds with human GSK-3 has been studied using molecular docking and 3D-QSAR approaches. In the 3D-QSAR studies, the molecular alignment and conformation determination are so important that they affect the success of a model. Flexible docking (AutoDock3.0.5) was used for the determination of 'active' conformation and molecular alignment. Comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) were used to develop 3D-QSAR models of 80 N-phenyl-4-pyrazolo[1,5-b]pyridazin-3-ylpyrimidin-2-amine compounds. The r(2) values were 0.870 and 0.861 for CoMFA and CoMSIA models, respectively. The predictive ability of these models was validated by 10 compounds of the test set. Mapping these models back to the topology of the active site of GSK-3 led to a better understanding of the vital N-phenyl-4-pyrazolo[1,5-b]pyridazin-3-ylpyrimidin-2-amines-GSK-3 interactions. The results demonstrate that combination of ligand-based and receptor-based modeling is a powerful approach to build 3D-QSAR models. The interaction mode from this study may be helpful for the design of a novel inhibitor and guide the selection of candidate sites for further experimental studies on site-directed mutagenesis.     

A Simplified Method for the Isolation and Estimation of Cell Wall Bound Glycogen in Saccharomyces cerevisiae

Glycogen is an important storage reserve in yeast. In Saccharomyces cerevisiae glycogen is present in two pools, an intracellular soluble pool and a cell wall bound, insoluble extra‐cellular pool. The present method uses a 20% KOH treatment to separate the two pools, which are then estimated using amyloglucosidase. The amount of soluble glycogen was found to be 6.5 mg/g of wet weight of yeast while that of cell wall bound glycogen was found to be almost three times that of the soluble, viz., 18 mg/g of wet weight of yeast. The data is compared with two earlier commonly used methods of yeast carbohydrate fractionation, which reported glycogen in totality. Reviewing these methods in the light of finding two pools of glycogen revealed that both the methods can be demonstrated to yield soluble glycogen in the range of 6–9 mg/g of yeast and 18–21 mg/g of wet weight of yeast of cell wall bound glycogen.     

Norepinephrine Regulation of Ventromedial Hypothalamic Nucleus Astrocyte Glycogen Metabolism

The catecholamine norepinephrine (NE) links hindbrain metabolic-sensory neurons with key glucostatic control structures in the brain, including the ventromedial hypothalamic nucleus (VMN). In the brain, the glycogen reserve is maintained within the astrocyte cell compartment as an alternative energy source to blood-derived glucose. VMN astrocytes are direct targets for metabolic stimulus-driven noradrenergic signaling due to their adrenergic receptor expression (AR). The current review discusses recent affirmative evidence that neuro-metabolic stability in the VMN may be shaped by NE influence on astrocyte glycogen metabolism and glycogen-derived substrate fuel supply. Noradrenergic modulation of estrogen receptor (ER) control of VMN glycogen phosphorylase (GP) isoform expression supports the interaction of catecholamine and estradiol signals in shaping the physiological stimulus-specific control of astrocyte glycogen mobilization. Sex-dimorphic NE control of glycogen synthase and GP brain versus muscle type proteins may be due, in part, to the dissimilar noradrenergic governance of astrocyte AR and ER variant profiles in males versus females. Forthcoming advances in the understanding of the molecular mechanistic framework for catecholamine stimulus integration with other regulatory inputs to VMN astrocytes will undoubtedly reveal useful new molecular targets in each sex for glycogen mediated defense of neuronal metabolic equilibrium during neuro-glucopenia.