A molecular dynamics study of the stoichiometric complex formed by poly (alpha, L-glutamate) and octyltrimethylammonium ions in chloroform solution.

We present a molecular dynamics simulation at 300 K in explicit solvent environment of chloroform of the stoichiometric complex formed by poly(alpha,L-glutamate) and octyltrimethylammonium ions. We observed that the alpha-helix conformation of the polypeptide chain remains stable during a 2-ns run. The surfactant ions predominantly adopted an extended conformation that is stabilized by favorable interactions with the organic solvent. Analysis of the organization of the surfactant with respect to the polypeptide chain indicated that each octyltrimethylammonium cation was preferentially bound to more than one carboxylate group. It was found that the most populated arrangement was that with the surfactant cations interacting with two carboxylate groups simultaneously.     

Effect of the oral hypoglycemic agent 2-tetradecylglycidic acid on fatty acid oxidation in suckling rats in vivo and in perfused liver

The hypoglycemic agent, 2-tetradecylglycidic acid (TDGA), administered in vivo lowered the concentration of plasma glucose and ketone bodies but raised the concentration of liver and plasma triglycerides in 10-day-old suckling rats. Phospholipid and cholesterol content of the plasma and liver were unaffected by drug treatment. TDGA inhibited the in vivo oxidation of [1-¹⁴C]palmitate but not that of [1-¹⁴C]decanoate. In suckling rat liver perfusion, TDGA totally inhibited ketone body formation from palmitate and depressed ketone body production from decanoate by 20%. Liver ATP and ADP content in the presence of TDGA decreased although this was probably a reflection of the increased triglyceride content of the liver since the $\text{ATP}\text{ADP}$ was the same as control livers. The results are discussed in relation to the diet and to the inhibition of carnitine acyl transferase in suckling rats.     

Focal contacts of spreading platelets with the substratum

Contacts with glass substratum formed by the spreading rabbit platelets were examined by an antibody-exclusion method; monoclonal antibodies against 80 kD bovine serum protein were used. It was found that platelets form focal contacts in the course of spreading. The size of the largest focal contacts formed by platelets is smaller than that of the contacts formed by fibroblasts. The antibody-exclusion method revealed focal contacts of platelets much more clearly than interference reflection microscopy (IRM). The similarity of reactions involved in spreading platelets and of large nucleus-containing tissue cells is discussed.     

siRNA干扰PDGF对新生儿血管瘤干细胞的增殖和分化的影响

婴儿血管瘤是一种血管瘤,表现出独特的快速生长的特征,然后随着时间而消退。血管瘤来自CD133+干细胞,当植入免疫缺陷小鼠时,它们分化成内皮细胞。同样克隆扩增的干细胞也产生脂肪细胞,从而重现血管瘤的消退期。本研究主要阐明了使用血管瘤来源的干细胞(hemSC)增殖和分化的内在机制。本研究发现血小板衍生生长因子(PDGF)在增殖期升高并可能抑制脂肪细胞分化。hemSC表达高水平的PDGF-b并且在基础(未刺激)条件下显示PDGF受体的持续酪氨酸磷酸化。PDGF受体信号传导的抑制导致hemSCs中的脂肪生成增强。此外,hemSCs暴露于外源性PDGF-b降低了脂肪含量和脂肪细胞特异性转录因子的表达。总之,本研究将PDGF信号传导鉴定为血管瘤退化的内在负调节因子,并强调了破坏PDGF信号传导治疗血管瘤的治疗潜力。     

Varicuothiols A and B,New Fungal Metabolites from Aspergillus versicolor with Anti‐Inflammatory Activities

Chemical examination of a coral‐associated fungus Aspergillus versicolor LZD‐44‐03 resulted in the isolation of two new compounds with the trivial names of varicuothiols A ( 1 ) and B ( 2 ) as a unique scaffold. Their structures were determined through extensive spectroscopic analyses in association with the modified Mosher's method and chemical conversion. Both 1 and 2 exhibited significant inhibition against LPS‐induced RAW24.7 cell proliferation, in association with the down regulation of nitrite production and cytokines (MCP‐1, IL‐6, and TNF‐α).     

Quercetin-induced yeast apoptosis through mitochondrial dysfunction under the accumulation of magnesium in Candida albicans

Latterly, the upsurge in use of antifungal drugs has brought about the emergence of several drug-resistance strains, making it skeptical to continue relying on current therapeutic regime. In the necessity of resistance-free antifungal agent, flavonoids presented possibilities of replacing existing drugs, displaying antifungal activity against pathogenic fungi. Among them, quercetin, one of the most representative flavonoids, exhibited antifungal activity against Candida albicans. To inspect the further understanding regarding quercetin, the antifungal mode of action of quercetin was investigated. In the initial step, the apoptosis was monitored after quercetin treatment. Moreover, intracellular levels of Mg²⁺ was assessed and was determined that Mg²⁺ increase occurred under the influence of quercetin. In addition, several features of mitochondrial dysfunction were monitored. Mitochondrial dysfunction triggers decrease in mitochondrial redox levels and leads to disruption in mitochondrial antioxidant system. Increased intracellular ROS and decreased intracellular redox levels were also displayed, indicating the occurrence of overall disruption in antioxidant systems. Sequentially, DNA fragmentation was observed and this DNA damage in turn induces apoptosis. In analyses, hexaamminecobalt(III) chloride (Cohex) was applied to inhibit Mg²⁺ transport between cytosol and mitochondria. Cohex attenuated the effects induced by quercetin, which demonstrates that the presence of Mg²⁺ is essential in quercetin-induced apoptosis.     

DNA reassociation kinetics and hybridization in different angiosperms

Reassociation kinetics ofDaucus carota andPetroselinum crispum (Apiaceae), andDatura innoxia (Solanaceae) are presented. Hybridization of³H-labelled DNA of two carrot cultivars indicate strong qualitative homologies of DNA sequences; nevertheless, certain quantitative differences in some Cotregions seem to exist. However, homologous sequences ofDaucus DNA with DNA ofDatura, and, suprisingly, even with DNA ofPetroselinum are very restricted: between 8% in the repeated regions and ca. 7–9% in the unique regions.     

Geographical distributions,relative abundance and coexistence of Drosophila aldrichi and Drosophila buzzatii in Australia

Abstract Climatic data and collection records for the cactophilic Drosophila aldrichi and Drosophila buzzatii for 97 localities were used to examine the effects of geographical location, season, host plant species and climatic factors on their range and relative abundance. Temporal variation in relative abundance was assessed from monthly collections over 4 years at one locality. Effects of weather variables over the 28 days before each collection were examined. A generalized linear model of the spatial data showed significant geographical variation in relative abundance, and significant climatic effects, with the proportion of D. aldrichi higher in the warm season, and increasing as temperature variation decreased and moisture indices increased. The temporal data gave generally concordant results, as D. aldrichi proportion was higher in summer and autumn, and increased as maximum and minimum temperatures increased, and as variation in maximum temperature decreased. In a laboratory competition experiment, D. aldrichi eliminated D. buzzatii at 31°C, but was itself eliminated at 18°C and 25°C. The range of D. buzzatii is constrained only by availability of its host plant, Opuntia species, although its relative abundance is reduced in the northern part of its distribution. The range of D. aldrichi, from central Queensland to northern NSW, Australia, is entirely within that of D. buzzatii, and its relative abundance decreases from north to south. Both climate and weather, particularly temperature variability, have direct effects on the relative abundances of the two species, and both likely act indirectly by influencing the outcome of interspecific competition.     

Dimeric chromenes and mixed dimers of a chromene with euparin from Encelia canescens

The investigation of Encelia canescens afforded, in addition to several known compounds, four new dimeric p-hydroxyacetophenone derivatives, two epimeric chromene dimers and two epimeric mixed dimers of euparin and encecalin. Furthermore, derivatives of tremetone and of encecalin were present. The structures were elucidated hy high field ¹H NMR spectroscopy.     

Root development in winter wheat grown at different N/P supply: Root length patterns and N-P interactions in phosphate uptake

Effects of different N/P ratios on several root parameters and on net P uptake were studied in winter wheat, Triticum aestivum cv. Starke II, grown in water culture. In the First experiment N/P ratios of (0/4, 2/3, 4/2, 6/1 and 8/0) were used, and plants were harvested at age 3, 5, 8, 11 and 14 days. In the second experiment N/P ratios of 6/1, 10/1, 15/1, 17/1, 20/1 and 25/1 were applied at two different N,P levels. Root length and number were determined using a digitizer connected to a computer. In the first experiment. the 6/1 N/P ratio gave the largest plants at day 14, and growth decreased with decreasing N/P ratio, The same pattern was found fur lateral root length and root number (seminal and lateral). In the second experiment the root weights decreased with increasing N/P ratio within each level. Lateral root number and overall length decreased with increasing N/P ratio at both levels as did the average lateral root length at the high N,P level. At the low N.P level, average lateral root length was about the same at all N/P ratios. Increasing the N/P ratio increased net uptake of P at the low N,P level, but decreased net P uptake at the high N,P level. Net P uptake increased with increasing P concentration in the roots and then decreased with further increase in P concentration. Net P uptake based on calculated root length [m (g root)⁻¹] showed no significant deviation from weight-based uptake plots. The effect of N and P on root structure is discussed as well as the interaction of N and P in P uptake. The relevance of a proper basis for expressing root activity is stressed.