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51.
Yoav Peleg Emil Battat Michael C. Scrutton Israel Goldberg 《Applied microbiology and biotechnology》1989,32(3):334-339
Summary Electrophoretic studies of fumarase and nicotine adenine dinucleotide (NAD)-malate dehydrogenase were carried out in the fumaric acid-accumulating fungus Rhizopus oryzae. The analyses revealed two fumarase isoenzymes, one localised solely in the cytosol and the other found both in the cytosol and in the mitochondrial fraction. The activity of the cytosolic isoenzyme of fumarase was higher during the acid production stage than during growth. Addition of cycloheximide inhibited fumaric acid production and decreased the activity of the cytosolic isoenzyme of fumarase. These results suggested that de novo protein synthesis is required for increase in the activity of the cytosolic isoenzyme and that such an increase in activity is essential for fumaric acid accumulation. Three distinct isoenzymes of NAD-malate dehydrogenase could be detected in R. oryzae. No changes were observed in the isoenzyme pattern of malate dehydrogenase during fumaric acid production. 相似文献
52.
Ben-Abraham R Gazit V Vofsi O Ben-Shlomo I Reznick AZ Katz Y 《Journal of cellular biochemistry》2003,90(5):957-963
Previous investigation demonstrated the potential of beta-phenylpyruvate at high concentration to cause hypoglycemia in mice totally deprived of insulin. For further elucidation of the glucose-lowering mechanism, glucose uptake, and quantity of glucose transporters (GLUT1 and GLUT4) in mouse soleus muscle and C2C12 muscle cell lines were investigated following incubation with beta-phenylpyruvate in various concentrations. A marked enhancement of glucose uptake was demonstrated that peaked at 0.5 and 1.0 mM beta-phenylpyruvate in soleus muscle (P<0.01) and C2C12 cells (P<0.001), respectively. Kinetic analysis in C2C12 cells showed a twofold increase in Vmax compared with controls (P<0.001). In addition, both GLUT1 and GLUT4 levels were increased following exposure to beta-phenylpyruvate. Our findings point to a peripheral hypoglycemic effect of beta-phenylpyruvate. 相似文献
53.
Transpiration rates of young Tamarix aphylla (L.) Karst, plants grown in hydroponics were measured under NaCl- and Cd(NO3 )2 -stress. Transpiration rates were negatively correlated with the relative humidity of the ambient air at all NaCl concentrations investigated. Low and intermediate concentrations of Cd2+ (45 and 90 μ M , respectively) in the medium caused an increase in transpiration rates. This was particularly pronounced at low levels of relative humidity. At 180 μ M Cd2+ , transpiration rates dropped, probably as a result of root damage due to Cd2+ toxicity. Since the transpiration rates differed by a factor of ca 3 between day and night, it is concluded that the stomata did not lose their ability to regulate transpiration under the influence of NaCl or of Cd(NO3 )2 . The transpiration behaviour of T. aphylla indicates that the effect of water vapour pressure (presented as relative humidity) on the degree of stomatal opening is small. Under conditions of ample water supply transpiration follows the evaporative demand of the ambient air and is influenced by the water uptake capacity of the root system as well as by other environmental factors, e.g. light. 相似文献
54.
Multiple display of catalytic modules on a protein scaffold: nano-fabrication of enzyme particles 总被引:2,自引:1,他引:1
Heyman A Barak Y Caspi J Wilson DB Altman A Bayer EA Shoseyov O 《Journal of biotechnology》2007,131(4):433-439
Self assembly is a prerequisite for fabricating nanoscale structures. Here we present a new fusion protein based on the stress-responsive homo-oligomeric protein, SP1. This ring-shaped protein is a highly stable homododecamer, which can be potentially utilized to self-assemble different modules and enzymes in a predicted and oriented manner. For that purpose, a cohesin module (a component of the bacterial cellulosome) was selected, its gene fused in-frame to SP1, and the fusion protein was expressed in Escherichia coli. The cohesin module, specialized to incorporate different enzymes through specific recognition of a dockerin modular counterpart, is used to display new moieties on the SP1 scaffold. The SP1 scaffold displayed 12 active cohesin modules and specific binding to a dockerin-fused cellulase enzyme from Thermobifida fusca. Moreover, we found a significant increase in specific activity of the scaffold-displayed enzymes. 相似文献
55.
Type 2 diabetes TCF7L2 risk genotypes alter birth weight: a study of 24,053 individuals 总被引:7,自引:0,他引:7 下载免费PDF全文
Freathy RM Weedon MN Bennett A Hypponen E Relton CL Knight B Shields B Parnell KS Groves CJ Ring SM Pembrey ME Ben-Shlomo Y Strachan DP Power C Jarvelin MR McCarthy MI Davey Smith G Hattersley AT Frayling TM 《American journal of human genetics》2007,80(6):1150-1161
The role of genes in normal birth-weight variation is poorly understood, and it has been suggested that the genetic component of fetal growth is small. Type 2 diabetes genes may influence birth weight through maternal genotype, by increasing maternal glycemia in pregnancy, or through fetal genotype, by altering fetal insulin secretion. We aimed to assess the role of the recently described type 2 diabetes gene TCF7L2 in birth weight. We genotyped the polymorphism rs7903146 in 15,709 individuals whose birth weight was available from six studies and in 8,344 mothers from three studies. Each fetal copy of the predisposing allele was associated with an 18-g (95% confidence interval [CI] 7-29 g) increase in birth weight (P=.001) and each maternal copy with a 30-g (95% CI 15-45 g) increase in offspring birth weight (P=2.8x10-5). Stratification by fetal genotype suggested that the association was driven by maternal genotype (31-g [95% CI 9-48 g] increase per allele; corrected P=.003). Analysis of diabetes-related traits in 10,314 nondiabetic individuals suggested the most likely mechanism is that the risk allele reduces maternal insulin secretion (disposition index reduced by ~0.15 standard deviation; P=1x10-4), which results in increased maternal glycemia in pregnancy and hence increased offspring birth weight. We combined information with the other common variant known to alter fetal growth, the -30G-->A polymorphism of glucokinase (rs1799884). The 4% of offspring born to mothers carrying three or four risk alleles were 119 g (95% CI 62-172 g) heavier than were the 32% born to mothers with none (for overall trend, P=2x10-7), comparable to the impact of maternal smoking during pregnancy. In conclusion, we have identified the first type 2 diabetes-susceptibility allele to be reproducibly associated with birth weight. Common gene variants can substantially influence normal birth-weight variation. 相似文献
56.
Palevitch O Kight K Abraham E Wray S Zohar Y Gothilf Y 《Cell and tissue research》2007,327(2):313-322
The ontogeny of two gonadotropin-releasing-hormone (GnRH) systems, salmon GnRH (sGnRH) and chicken GnRH-II (cGnRH-II), was
investigated in zebrafish (Danio rerio). In situ hybridization (ISH) first detected sGnRH mRNA-expressing cells at 1 day post-fertilization (pf) anterior to the
developing olfactory organs. Subsequently, cells were seen along the ventral olfactory organs and the olfactory bulbs, reaching
the terminal nerve (TN) ganglion at 5–6 days pf. Some cells were detected passing posteriorly through the ventral telencephalon
(10–25 days pf), and by 25–30 days pf, sGnRH cells were found in the hypothalamic/preoptic area. Continuous documentation
in live zebrafish was achieved by a promoter-reporter expression system. The expression of enhanced green fluorescent protein
(EGFP) driven by the sGnRH promoter allowed the earlier detection of cells and projections and the migration of sGnRH neurons.
This expression system revealed that long leading processes, presumably axons, preceded the migration of the sGnRH neuron
somata. cGnRH-II mRNA expressing cells were initially detected (1 day pf) by ISH analysis at lateral aspects of the midbrain
and later on (starting at 5 days pf) at the midline of the midbrain tegmentum. Detection of red fluorescent protein (DsRed)
driven by the cGnRH-II promoter confirmed the midbrain expression domain and identified specific hindbrain and forebrain cGnRH-II-cells
that were not identified by ISH. The forebrain DsRed-expressing cells seemed to emerge from the same site as the sGnRH-EGFP-expressing
cells, as revealed by co-injection of both constructs. These studies indicate that zebrafish TN and hypothalamic sGnRH cell
populations share a common embryonic origin and migratory path, and that midbrain cGnRH-II cells originate within the midbrain.
This study was supported by the US-Israel Bi-national Agricultural Research and Development (BARD) Foundation (grant 3428-03). 相似文献
57.
Amdursky N Beker P Koren I Bank-Srour B Mishina E Semin S Rasing T Rosenberg Y Barkay Z Gazit E Rosenman G 《Biomacromolecules》2011,12(4):1349-1354
Phase transitions in organic and inorganic materials are well-studied classical phenomena, where a change in the crystal space group symmetry induces a wide variation of physical properties, permitted by the crystalline symmetry in each phase. Here we observe a conformational induced transition in bioinspired peptide nanotubes (PNTs). We found that the PNTs change their original molecular assembly from a linear peptide conformation to a cyclic one, followed by a change of the nanocrystalline structure from a noncentrosymmetric hexagonal space group to a centrosymmetric orthorhombic space group. The observed transition is irreversible and induces a profound variation in the PNTs properties, from the microscopic to the macroscopic level. In this context, we follow the unique changes in the molecular, morphological, piezoelectric, second harmonic generation, and wettability properties of the PNTs. 相似文献
58.
We determined the probability of individuals having the ‘optimal’ mitochondrial biogenesis related endurance polygenic profile, and compared the endurance polygenic profile of Israeli (Caucasian) endurance athletes (n = 74), power athletes (n = 81), and non-athletes (n = 240). We computed a mitochondrial biogenesis related ‘endurance genotype score’ (EGS, scoring from 0 to 100) from the accumulated combination of six polymorphisms in the PPARGC1A-NRF-TFAM pathway. Some of the variant alleles of the polymorphisms studied were so infrequent, that the probability of possessing an ‘optimal’ EGS (= 100) was 0% in the entire study population. However, the EGS was significantly higher (P < 0.001) in endurance athletes (38.9 ± 17.1) compared with controls (30.6 ± 12.4) or power athletes (29.0 ± 11.2). In summary, although the probability of an individual possessing a theoretically ‘optimal’ genetic background for endurance sports is very low, in general endurance athletes have a polygenic profile that is more suitable for mitochondrial biogenesis. 相似文献
59.
Wills AK Lawlor DA Matthews FE Sayer AA Bakra E Ben-Shlomo Y Benzeval M Brunner E Cooper R Kivimaki M Kuh D Muniz-Terrera G Hardy R 《PLoS medicine》2011,8(6):e1000440
Background
Much of our understanding of the age-related progression of systolic blood pressure (SBP) comes from cross-sectional data, which do not directly capture within-individual change. We estimated life course trajectories of SBP using longitudinal data from seven population-based cohorts and one predominantly white collar occupational cohort, each from the United Kingdom and with data covering different but overlapping age periods.Methods and Findings
Data are from 30,372 individuals and comprise 102,583 SBP observations spanning from age 7 to 80+y. Multilevel models were fitted to each cohort. Four life course phases were evident in both sexes: a rapid increase in SBP coinciding with peak adolescent growth, a more gentle increase in early adulthood, a midlife acceleration beginning in the fourth decade, and a period of deceleration in late adulthood where increases in SBP slowed and SBP eventually declined. These phases were still present, although at lower levels, after adjusting for increases in body mass index though adulthood. The deceleration and decline in old age was less evident after excluding individuals who had taken antihypertensive medication. Compared to the population-based cohorts, the occupational cohort had a lower mean SBP, a shallower annual increase in midlife, and a later midlife acceleration. The maximum sex difference was found at age 26 (+8.2 mm Hg higher in men, 95% CI: 6.7, 9.8); women then experienced steeper rises and caught up by the seventh decade.Conclusions
Our investigation shows a general pattern of SBP progression from childhood in the UK, and suggests possible differences in this pattern during adulthood between a general population and an occupational population. Please see later in the article for the Editors'' Summary 相似文献60.