Development,survival, body weight,longevity, and reproductive potential of Oemena hirta (Coleoptera: Cerambycidae) under different rearing conditions

Oemona hirta (F.) is a New Zealand native longicorn beetle, whose larvae bore into the wood of branches and stems of living trees and vines, causing serious damage. To explore effective methods for maintaining laboratory colonies and biology of immature stages of this species we evaluated four laboratory rearing methods with both natural and artificial diets and compared biological parameters of laboratory colonies with those of field-collected insects. On an artificial diet, approximately 40% of neonate and 70% of autumn- and 11% of winter-collected larvae reached adulthood. Neonate larvae could not complete their development in cut poplar (Populus nigra variety italica Koehne) twigs; however, when twigs were standing in water >46% of neonate larvae survived to adulthood. Mean larval development time ranged from approximately150 to almost 300 d, depending on rearing methods. Mean pupal stage ranged from 15 to 19 d. Adult females were significantly heavier than males. Although adult females from field-collected twigs and reared on the artificial diet had similar mean body weight, which was significantly greater than that of other rearing colonies, the potential fecundity was the highest in the former (83.1 +/- 29.4 eggs) and the lowest in the latter (33.5 +/- 9.1 eggs). In all laboratory-reared and field-collected insects, the total number of eggs produced (eggs laid + eggs that remained in dead female body) by females was positively correlated with their body weight. When larvae fed on the artificial diet, there was no positive correlation between the number of eggs successfully laid and female body weight. However, when larvae lived on natural food, a positive correlation was found. In laboratory colonies, mean longevity of females (36 to 52 d) was slightly greater than that of males (30 to 50 d) without significant difference between sexes but in the adults from field-collected twigs, males (52 d) lived significantly longer than females (33 d). In terms of time, labor, and the number of resulting adults, collecting larvae in the field in autumn and then transferring them onto artificial diet is the most effective method for maintaining a laboratory colony.     

p39, the Primary Activator for Cyclin-dependent Kinase 5 (Cdk5) in Oligodendroglia,Is Essential for Oligodendroglia Differentiation and Myelin Repair

Cyclin-dependent kinase 5 (Cdk5) plays key roles in normal brain development and function. Dysregulation of Cdk5 may cause neurodegeneration and cognitive impairment. Besides the well demonstrated role of Cdk5 in neurons, emerging evidence suggests the functional requirement of Cdk5 in oligodendroglia (OL) and CNS myelin development. However, whether neurons and OLs employ similar or distinct mechanisms to regulate Cdk5 activity remains elusive. We report here that in contrast to neurons that harbor high levels of two Cdk5 activators, p35 and p39, OLs express abundant p39 but negligible p35. In addition, p39 is selectively up-regulated in OLs during differentiation along with elevated Cdk5 activity, whereas p35 expression remains unaltered. Specific knockdown of p39 by siRNA significantly attenuates Cdk5 activity and OL differentiation without affecting p35. Finally, expression of p39, but not p35, is increased during myelin repair, and remyelination is impaired in p39^−/− mice. Together, these results reveal that neurons and OLs harbor distinct preference of Cdk5 activators and demonstrate important functions of p39-dependent Cdk5 activation in OL differentiation during de novo myelin development and myelin repair.     

Enhanced freeze tolerance of baker’s yeast by overexpressed trehalose-6-phosphate synthase gene (TPS1) and deleted trehalase genes in frozen dough

Several recombinant strains with overexpressed trehalose-6-phosphate synthase gene (TPS1) and/or deleted trehalase genes were obtained to elucidate the relationships between TPS1, trehalase genes, content of intracellular trehalose and freeze tolerance of baker’s yeast, as well as improve the fermentation properties of lean dough after freezing. In this study, strain TL301_TPS1 overexpressing TPS1 showed 62.92 % higher trehalose-6-phosphate synthase (Tps1) activity and enhanced the content of intracellular trehalose than the parental strain. Deleting ATH1 exerted a significant effect on trehalase activities and the degradation amount of intracellular trehalose during the first 30 min of prefermentation. This finding indicates that acid trehalase (Ath1) plays a role in intracellular trehalose degradation. NTH2 encodes a functional neutral trehalase (Nth2) that was significantly involved in intracellular trehalose degradation in the absence of the NTH1 and/or ATH1 gene. The survival ratio, freeze-tolerance ratio and relative fermentation ability of strain TL301_TPS1 were approximately twice as high as those of the parental strain (BY6-9α). The increase in freeze tolerance of strain TL301_TPS1 was accompanied by relatively low trehalase activity, high Tps1 activity and high residual content of intracellular trehalose. Our results suggest that overexpressing TPS1 and deleting trehalase genes are sufficient to improve the freeze tolerance of baker’s yeast in frozen dough. The present study provides guidance for the commercial baking industry as well as the research on the intracellular trehalose mobilization and freeze tolerance of baker’s yeast.     

Pyruvate decarboxylase and alcohol dehydrogenase overexpression in Escherichia coli resulted in high ethanol production and rewired metabolic enzyme networks

Pyruvate decarboxylase and alcohol dehydrogenase are efficient enzymes for ethanol production in Zymomonas mobilis. These two enzymes were over-expressed in Escherichia coli, a promising candidate for industrial ethanol production, resulting in high ethanol production in the engineered E. coli. To investigate the intracellular changes to the enzyme overexpression for homoethanol production, 2-DE and LC–MS/MS were performed. More than 1,000 protein spots were reproducibly detected in the gel by image analysis. Compared to the wild-type, 99 protein spots showed significant changes in abundance in the recombinant E. coli, in which 46 were down-regulated and 53 were up-regulated. Most proteins related to tricarboxylic acid cycle, glycerol metabolism and other energy metabolism were up-regulated, whereas proteins involved in glycolysis and glyoxylate pathway were down-regulated, indicating the rewired metabolism in the engineered E. coli. As glycolysis is the main pathway for ethanol production, and it was inhibited significantly in engineered E. coli, further efforts should be directed at minimizing the repression of glycolysis to optimize metabolism network for higher yields of ethanol production.     

植物类型Ⅲ聚酮合酶超家族基因结构、功能及代谢产物

植物聚酮类化合物主要包括酚类、芪类及类黄酮化合物等,在植物花色、防止紫外线伤害、预防病原菌、昆虫危害以及作为植物与环境互作信号分子方面行使着重要的生物学功能。该类化合物具有显著多样的生物学活性,对人体保健及疾病治疗有显著意义。植物类型Ⅲ聚酮化合物合酶(PKS)在该类化合物生物合成起始反应中行使着关键作用,决定该类化合物基本分子骨架建成和代谢途径碳硫走向,为合成途径关键酶和限速酶。以查尔酮合酶为原型酶的植物类型Ⅲ PKS超家族是研究系统进化和蛋白结构与功能关系的模式分子家族,目前已经分离得到14种植物类型Ⅲ PKS基因,这些同祖同源基因及其表达产物既有共性,也表现出许多独特个性,这些个性赋予此类次生代谢产物结构上的多样性。以下综述了植物类型Ⅲ PKS超家族基因结构、功能及代谢产物研究进展。     

适应性实验室进化在工业生产菌株选育中应用的进展

适应性实验室进化是一种在实验室里将微生物置于一定选择压力下,通过长期驯化,筛选获得具有特定表型突变菌株的方法.近年来,该方法通过改进特定进化条件和筛选策略,已广泛应用于筛选具有优良特性的工业生产菌株,如特定表型筛选、底物高效利用、目标产物合成及生长特性优化等工业微生物菌株选育.本文综述了适应性实验室进化技术在工业生产菌...