Pre-anthesis high-temperature acclimation alleviates damage to the flag leaf caused by post-anthesis heat stress in wheat

The objective of this study was to investigate the effect of pre-anthesis high-temperature acclimation on leaf physiology of winter wheat in response to post-anthesis heat stress. The results showed that both pre- and post-anthesis heat stresses significantly depressed flag leaf photosynthesis and enhanced cell membrane peroxidation, as exemplified by increased O₂^{−com/sd/entities/rad" class="glyphImg">} production rate and reduction in activities of antioxiditave enzymes. However, under post-anthesis heat stress, plants with pre-anthesis high-temperature acclimation (HH) showed much higher photosynthetic rates than those without pre-anthesis high-temperature acclimation (CH). Leaves of HH plants exhibited a higher Chl a/b ratio and lower chlorophyll/carotenoid ratio and superoxide anion radical release rate compared with those of the CH plants. In addition, antioxidant enzyme activities in HH plants were significantly higher than in CH. Coincidently, expressions of photosythesis-responsive gene encoding Rubisco activase B (RcaB) and antioxidant enzyme-related genes encoding mitochondrial manganese superoxide dismutase (Mn-SOD), chloroplastic Cu/Zn superoxide dismutase (Cu/Zn-SOD), catalase (CAT) and cytosolic glutathione reductase (GR) were all up-regulated under HH, whereas a gene encoding a major chlorophyll a/b-binding protein (Cab) was up-regulated by post-anthesis heat stress at 10 DAA, but was down-regulated at 13 DAA. The changes in the expression levels of the HH plants were more pronounced than those for the CH. Collectively, the results indicated that pre-anthesis high-temperature acclimation could effectively alleviate the photosynthetic and oxidative damage caused by post-anthesis heat stress in wheat flag leaves, which was partially attributable to modifications in the expression of the photosythesis-responsive and antioxidant enzymes-related genes.     

The alpha-galactosyl derivatives of ganglioside GD(1b) are essential for the organization of lipid rafts in RBL-2H3 mast cells

Gangliosides are complex glycosphingolipids that are important in many biological processes. The present study investigated the role of gangliosides in the organization of lipid rafts in RBL-2H3 mast cells and in the modulation of mast cell degranulation via Fccom/scidirimg/entities/25b.gif" alt="var epsilon" title="var epsilon" border="0">RI. The role of gangliosides was examined using two ganglioside deficient cell lines (B6A4A2III-E5 and B6A4C1III-D1) as well as the parent cell line (RBL-2H3). All three cell lines examined express Fccom/scidirimg/entities/25b.gif" alt="var epsilon" title="var epsilon" border="0">RI, Lyn, Syk and LAT. However, only in RBL-2H3 cells were Fccom/scidirimg/entities/25b.gif" alt="var epsilon" title="var epsilon" border="0">RI, LAT and α-galactosyl derivatives of ganglioside GD_1b mobilized to lipid raft domains following Fccom/scidirimg/entities/25b.gif" alt="var epsilon" title="var epsilon" border="0">RI stimulation. The inhibition of glycosphingolipid synthesis in RBL-2H3 cells also resulted in a decrease in the release of β-hexosaminidase activity after Fccom/scidirimg/entities/25b.gif" alt="var epsilon" title="var epsilon" border="0">RI activation. The two mutant cell lines have a reduced release of β-hexosaminidase activity after Fccom/scidirimg/entities/25b.gif" alt="var epsilon" title="var epsilon" border="0">RI stimulation, but not after exposure to calcium ionophore. These results indicate that the α-galactosyl derivatives of ganglioside GD_1b are important in the initial events of Fccom/scidirimg/entities/25b.gif" alt="var epsilon" title="var epsilon" border="0">RI signaling upstream of Ca²⁺ influx. Since the initial signaling events occur in lipid rafts and in the mutant cell lines the rafts are disorganized, these results also suggest that these gangliosides contribute to the correct assembly of lipid rafts and are essential for mast cell activation via Fccom/scidirimg/entities/25b.gif" alt="var epsilon" title="var epsilon" border="0">RI.     

大兴安岭紫貂食物组成分析

在大兴安岭地区, 从1995 年12 月至1996 年11 月在颈环遥测的4 只紫貂活动的范围内共收集紫貂粪样295个, 采用频率法和剩余物相对干重法进行分析, 得出紫貂全年食物组成及比例: 哺乳类(出现率72.09 % , 剩余物干重百分比84.06 %) , 植物浆果及种子(14.51 % , 11.09 %) , 鸟类(7.69 % , 4.24 %) 和昆虫(5.71 % , 0.96 %) 。其中红背　和棕背　构成紫貂食物的主要部分, 其次为松籽、越桔果和花尾榛鸡。紫貂食物组成季节性变化明显, 夏季食物种类丰富, 且比例较均衡; 冬季食物多样性低。文中还对两种粪样分析方法所得结果进行了比较,证明这两种方法在对主要食物种( 出现次数≥5) 的分析评述上是一致的, 无显著差异。     

Systeme cytochromique des membranes cytoplasmiques et des membranes mesosomiques de Bacillus subtilis

The cytochromes of cytoplasmic and mesosomal membranes of Bacillus subtilis     

Metabolism of cortisone-4- 14 C by rat lung tissue

The metabolism of cortisone-4-¹⁴C has been studied in male rat lung tissue preparations. Data indicate the presence of 11β-hydroxysteroid dehydrogenase, Δ⁴-5α-reductase, 3α-hydroxysteroid dehydrogenase and 20α-hydroxysteroid dehydrogenase activity in this tissue. Metabolites identified were hydrocortisone, 17α, 20α, 21-trihydroxy-4-pregnene-3, 11-dione and 3α, 17α, 21-trihydroxy-5α-pregnan-11,20-dione.     

Cellular, synaptic, network, and modulatory mechanisms involved in rhythm generation

The membrane properties and the synaptic interactions of individual neurons, as well as the interactions between neuronal networks, all contribute to the formation of the complex patterns of activity that underlie rhythmic motor patterns and slow-wave sleep rhythms. These properties and interactions are potential points of modulation for further refining network output. Recent work illustrates the range of these properties and interactions and suggests how they may be modulated.     

Polyphenol-enriched fractions from Sicilian grape pomace: HPLC-DAD analysis and antioxidant activity

On the basis of a preliminary screening of seven different samples of Sicilian grape pomace, the 'Nerello Mascalese' sample NM2 was selected for an ethanol preparative extraction. The defatted NM2 EtOH extract was subjected to DPPH() and GAE assays, showing good radical scavenging activity (SC(50)=9.9 microg/mL) and a GAE value of 397.7 mg/g extract. HPLC-DAD analysis of NM2 extract allowed a quantitative determination of the main anthocyanins (AN) and flavonols/flavonol glycosides (FL/FG). Aliquots of the NM2 extract were subjected to three different fractionation protocols (FP1, FP2 and FP3). The fractions were examined by DPPH() and GAE assays, and subjected to HPLC-DAD analysis for the quantitative determination of the main AN and FL/FG. FP3 allowed obtaining a polyphenol-enriched fraction with SC(50)=14.8 microg/mL and GAE=184.1mg/g of fraction, accounting for only 1.3% in weight of the EtOH extract. Some considerations about the relationship between antioxidant activity and AN/FL/FG HPLC-DAD profiles are also reported.