Qualitative yeast enzyme analysis by electrophoresis

Summary Baker's yeast (Saccharomyces cerevisiae) was cultivated under different intensities of aeration on glucose and on ethanol. Seventeen enzymes of the Embden-Meyerhof pathway and the TCA cycle or related reactions were then assayed by starch gel electrophoresis. There were both qualitative and quantitative differences in many enzymes, most notably in glyceraldehyde-3-phosphate dehydrogenase, alcohol dehydrogenase, isocitrate dehydrogenase, malate dehydrogenase, and fumarase. Enzyme electrophoresis seems to offer a promising method for rapidly obtaining information about many yeast enzymes from a large number of samples.     

Incompatibility of outer membrane proteins OmpA and OmpF of Escherichia coli with secretion in Bacillus subtilis: Fusions with secretable peptides

The secretion of the outer membrane proteins OmpA and OmpF of Escherichia coli has previously been found to be blocked at an early intracellular step, when these proteins were fused to a bacillar signal sequence and expressed in Bacillus subtilis. We have now fused these proteins to long secretable polypeptides, the amino-terminal portions of alpha-amylase or beta-lactamase. In spite of this, no secretion of the fusion proteins was detected in B. subtilis. With the exception of a small fraction of the beta-lactamase fusion, the proteins were cell-bound with uncleaved signal sequences. Protease accessibility indicated that the fusion proteins were not even partially exposed on the outer surface of the cytoplasmic membrane. Thus there was no change of the location compared to the OmpA or OmpF fused to the signal sequence only. We conclude that, like OmpA and OmpF, the fusion proteins fold into an export-incompatible conformation in B. subtilis before the start of translocation, which we postulate to be a late post-translational event.     

D-xylose catabolism in fusarium oxysporum

Summary The initial steps of D-xylose catabolism inFusarium oxysporum have been studied. The presence of the oxidoreductase pathway for D-xylose catabolism was demonstrated. The enzymes involved, D-xylose reductase and xylitol dehydrogenase, were found to be inducible and relatively specific for D-xylose and xylitol. D-xylose isomerase was not detected.     

Multidimensional plasticity in the Glanville fritillary butterfly: larval performance is temperature,host and family specific

Variation in environmental conditions during development can lead to changes in life-history traits with long-lasting effects. Here, we study how variation in temperature and host plant (i.e. the consequences of potential maternal oviposition choices) affects a suite of life-history traits in pre-diapause larvae of the Glanville fritillary butterfly. We focus on offspring survival, larval growth rates and relative fat reserves, and pay specific attention to intraspecific variation in the responses (G × E × E). Globally, thermal performance and survival curves varied between diets of two host plants, suggesting that host modifies the temperature impact, or vice versa. Additionally, we show that the relative fat content has a host-dependent, discontinuous response to developmental temperature. This implies that a potential switch in resource allocation, from more investment in growth at lower temperatures to storage at higher temperatures, is dependent on the larval diet. Interestingly, a large proportion of the variance in larval performance is explained by differences among families, or interactions with this variable. Finally, we demonstrate that these family-specific responses to the host plant remain largely consistent across thermal environments. Together, the results of our study underscore the importance of paying attention to intraspecific trait variation in the field of evolutionary ecology.     

Liver-Fat Accumulation and Insulin Resistance in Obese Women with Previous Gestational Diabetes

Objective: We determined whether fat accumulation in the liver is associated with features of insulin resistance independent of obesity. Research Methods and Procedures: We recruited 27 obese nondiabetic women in whom liver fat (LFAT) content was determined by proton spectroscopy, intra-abdominal and subcutaneous fat by magnetic resonance imaging, and insulin sensitivity by the euglycemic insulin clamp technique. The women were divided based on their median LFAT content (5%) to groups with low (3.2 ± 0.3%) and high (9.8 ± 1.5%) liver fat. The groups were almost identical with respect to age (36 ± 1 vs. 38 ± 1 years in low vs. high-LFAT), body mass index (32.2 ± 0.6 vs. 32.8 ± 0.5 kg/m²), waist-to-hip ratio, intra-abdominal, subcutaneous, and total fat content. Results: Women with high LFAT had features of insulin resistance including higher fasting serum triglyceride (1.93 ± 0.21 vs. 1.11 ± 0.09 mM, p < 0.01) and insulin (14 ± 3 vs. 10 ± 1 mU/L, p < 0.05) concentrations than women with low LFAT. The group with high LFAT also had higher 24-hour blood pressures, and lower whole-body insulin sensitivity compared with the low-LFAT group. Discussion: In obese women with previous gestational diabetes, LFAT, rather than any measure of body composition, is associated with features of insulin resistance.     

The cell-envelope glycolipids of baker''s yeast

Sphingolipids were found to dominate in the glycolipids from the cell envelope of baker's yeast. A relatively large quantity of ceramides was detected. Among the several complex phosphosphingolipids described, ceramide-(P-inositol)(2)-mannose was the main component. About 55% of long-chain bases in sphingolipids consisted of C(18)-phytosphingosine (4D-hydroxysphinganine). Other bases, found in decreasing concentrations, were C(20)-phytosphingosine, C(20)-dehydrophytosphingosine, C(18)-dihydrosphingosine (sphinganine) and C(19)-dihydrosphingosine. The presence of sterol glycosides, sulpholipids, cerebrosides and acylglucoses was demonstrated.     

Über die Anpassung der Bäckerhefe an Galaktose

Zusammenfassung Die mit Einsporen-Kulturen der Bäckerhefe durchgeführten Versuche weisen darauf hin, daß die untersuchten homozygotischen Bäckerhefestämme durch Anpassung imstande waren, Galaktose zu vergären, so daß diese Erscheinung mit der genotypischen Variation nichts zu tun hat.     

Der Chromosomencyclus von Macrosiphum pisi Kalt (Aphididae)

Ohne Zusammenfassung