Role of Raf in vascular protection from distinct apoptotic stimuli

Raf kinases have been linked to endothelial cell survival. Here, we show that basic fibroblast growth factor (bFGF) and vascular endothelial growth factor (VEGF) differentially activate Raf, resulting in protection from distinct pathways of apoptosis in human endothelial cells and chick embryo vasculature. bFGF activated Raf-1 via p21-activated protein kinase-1 (PAK-1) phosphorylation of serines 338 and 339, resulting in Raf-1 mitochondrial translocation and endothelial cell protection from the intrinsic pathway of apoptosis, independent of the mitogen-activated protein kinase kinase-1 (MEK1). In contrast, VEGF activated Raf-1 via Src kinase, leading to phosphorylation of tyrosines 340 and 341 and MEK1-dependent protection from extrinsic-mediated apoptosis. These findings implicate Raf-1 as a pivotal regulator of endothelial cell survival during angiogenesis.     

Role of BAX in the apoptotic response to anticancer agents

To assess the role of BAX in drug-induced apoptosis in human colorectal cancer cells, we generated cells that lack functional BAX genes. Such cells were partially resistant to the apoptotic effects of the chemotherapeutic agent 5-fluorouracil, but apoptosis was not abolished. In contrast, the absence of BAX completely abolished the apoptotic response to the chemopreventive agent sulindac and other nonsteroidal anti-inflammatory drugs (NSAIDs). NSAIDs inhibited the expression of the antiapoptotic protein Bcl-XL, resulting in an altered ratio of BAX to Bcl-XL and subsequent mitochondria-mediated cell death. These results establish an unambiguous role for BAX in apoptotic processes in human epithelial cancers and may have implications for cancer chemoprevention strategies.     

Mechanisms of AIF-mediated apoptotic DNA degradation in Caenorhabditis elegans

Apoptosis-inducing factor (AIF), a mitochondrial oxidoreductase, is released into the cytoplasm to induce cell death in response to apoptotic signals. However, the mechanisms underlying this process have not been resolved. We report that inactivation of the Caenorhabditis elegans AIF homolog wah-1 by RNA interference delayed the normal progression of apoptosis and caused a defect in apoptotic DNA degradation. WAH-1 localized in C. elegans mitochondria and was released into the cytosol and nucleus by the BH3-domain protein EGL-1 in a caspase (CED-3)-dependent manner. In addition, WAH-1 associated and cooperated with the mitochondrial endonuclease CPS-6/endonuclease G (EndoG) to promote DNA degradation and apoptosis. Thus, AIF and EndoG define a single, mitochondria-initiated apoptotic DNA degradation pathway that is conserved between C. elegans and mammals.     

Rat heart papillary muscles: action potentials and mechanical response to paired stimuli

Electrical reexcitation of rat papillary muscle after a short interval (50 to 80 milliseconds) results in action potentials with no significant mechanical counterpart. The mechanical response recovers as the interval is increased beyond 80 milliseconds. The rate of recovery is slowed at low external calcium levels. It appears that the coupling mechanism passes through a refractory stage owing to the depletion of an intracellular "releasable calcium" fraction.     

云南松解剖特征及其对外界刺激的响应

松脂是松属Pinus植物分泌的一种次生代谢产物,具有较高的经济价值和生态价值,主要储藏在松属植物针叶、树干木质部和韧皮部的树脂道系统内。开展云南松Pinus yunnanensis产脂量与其解剖学特征之间的关系研究,有利于云南松高产脂优树的选育和高产林定向培育技术体系的建立。对云南松产脂量与针叶、树干解剖特征之间的相关关系进行了研究,并比较分析了高、低产脂量云南松针叶和树干解剖特征的差异。结果表明:高产脂量云南松针叶树脂道个数、针叶分泌细胞个数、树干韧皮部树脂道个数、木质部树脂道个数和木质部分泌细胞个数极显著高于低产脂量云南松。随着针叶树脂道个数、针叶分泌细胞个数、树干韧皮部树脂道个数、木质部树脂道个数和木质部分泌细胞个数的增加,云南松的产脂量也不断增加(P < 0.01)。主成分分析中木质部树脂道个数的载荷值最大,表明云南松树干木质部树脂道与其产脂量关系最为密切。树干木质部树脂道个数可作为选育高产脂云南松的一个重要指标。     

苄嘧磺隆降解菌BP-H-01的分离及降解特性

【目的】分离筛选苄嘧磺隆的高效降解菌株,为磺酰脲类除草剂土壤残留危害的综合治理提供候选生物制剂。【方法】采用查氏培养基,从采自全国5省市的23份土壤样品中筛选降解菌,以苄嘧磺隆为唯一碳源进行摇瓶培养复筛,以相对降解率为评价标准,确定高效降解菌株,根据形态初步鉴定其种属,研究其降解特性。【结果】从土壤中分离筛选出能耐受500mg/L苄嘧磺隆的真菌与细菌菌株共计78株,其中共培养2d后,菌株BP-H-01对25～500mg/L苄嘧磺隆的相对降解率达80%以上,根据形态学特征初步确定该菌株为曲霉属(Aspergillus sp.)真菌。菌株BP-H-01降解苄嘧磺隆的最适pH为7.5,最适温度为28℃,初始接菌量2g/L,在此条件下相对降解率可达84.5%。【结论】菌株BP-H-01对苄嘧磺隆具有显著降解效果。     

二氯喹啉酸在烟草水培液中的消解动态及对烟苗生长的影响

在烟草水培液中添加二氯喹啉酸,采用高效液相色谱分析法检测烟苗移栽后0、3、7、24 h和30天二氯喹啉酸的消解率,结果表明:当添加量为0.36 mg/L时,其消解方程为Cx=0.1833e-0.0387t,半衰期为11.81天,r为0.9386;当添加量为0.18 mg/L时,其消解方程为Cx=0.1048e-0.0276t,半衰期为17.79天,r为0.8495.二氯喹啉酸对烟草幼苗生长的影响测定结果表明,在0.0005～5 mg/L浓度范围内,烟苗的根短、茎长、鲜重轻,根长和烟芽鲜重明显受到抑制;在浓度为5 mg/L时,畸形苗率达35%.     

Gratings mask bars and bars mask gratings: visual frequency response to aperiodic stimuli

Gratings and bars produce unexpected mutual visual masking. A grating masks a bar much less than a bar masks a bar; and a bar masks a grating uniformly over the grating field. These effects suggest that neural populations selective for size and orientation may be involved in frequency analysis rather than in simple feature detection.     

Auditory evoked response: meaningfulness of stimuli and interhemispheric asymmetry

Interhemispheric asymmetries of different magnitudes were observed in human cortical auditory evoked responses to speech and sound-effect stimuli. The wave with peak asymmetry occurred 100 milliseconds after signal onset. The amount of asymmetry of the amplitude of this wave was related to the meaningfulness to the subject of the auditory stimulus rather than to the mere use of verbal versus nonverbal materials.     

"Decision"-making in bacteria: chemotactic response of Escherichia coli to conflicting stimuli

Motile bacteria presented simultaneously with both attractant and repellent respond to whichever one is present in the more effective concentration. Apparently bacteria have a processing mechanism that compares opposing signals from the chemoreceptors for positive and negative taxis, sums these signals up, and then communicates the sum to the flagella.     

青藏高原高寒草地退化与人工恢复过程中植物群落的繁殖适应对策

以三江源区不同退化程度高寒草甸和不同恢复年限人工草地作为研究对象,通过野外调查与采样、实验室分析,探究了高寒地区退化天然草地与人工恢复草地的植被群落繁殖构件数量变化。结果表明：在群落水平上,天然草地退化和人工草地建植会对植物繁殖构件的数量和生物量产生影响。随着天然草地退化程度的增加,营养枝数量和生物量则明显下降,而繁殖枝的数量和生物量明显升高（P<0.05）;随着人工草地恢复年限的增加,营养枝的数量和生物量逐渐增加,而繁殖枝的数量和生物量则逐渐降低（P<0.05）;随着恢复年限的增加,人工草地繁殖构件的变化逐渐接近未退化天然草地。在功能群水平上,植物繁殖构件数量亦随草地退化程度和人工恢复年限而变化。随着恢复年限的增加,禾本科、莎草科、杂类草的营养枝数量和生物量均呈现显著增加（P<0.05）,而繁殖枝数量和生物量则显著下降,禾本科的繁殖构件数量远远大于莎草科和杂类草;随着退化程度的增加,三大功能群的营养枝枝数和生物量显著增加（P<0.05）,而繁殖枝则呈现相反的趋势。本研究实证了草地退化和人工恢复改变植物群落繁殖分配对策的科学假设,为高寒草地植被恢复重建技术的发展和更新提供理论支撑。     

Marine phytoplankton vary in their response to chlorinated hydrocarbons

Photosynthesis and growth in cultures of four marine phytoplankton species, isolated from different oceanic environments, were affected by three chlorinated hydrocarbons (DDT, dieldrin, and endrin) to varying extents. This ranged from complete insensitivity in Dunaliella to toxicity at concentrations of 0.1 to 1.0 part per billion of the pesticides in Cyclotella. Other forms were intermediate in their response.     

Detecting and measuring cotranslational protein degradation in vivo

Nascent polypeptides emerging from the ribosome and not yet folded may at least transiently present degradation signals similar to those recognized by the ubiquitin system in misfolded proteins. The ubiquitin sandwich technique was used to detect and measure cotranslational protein degradation in living cells. More than 50 percent of nascent protein molecules bearing an amino-terminal degradation signal can be degraded cotranslationally, never reaching their mature size before their destruction by processive proteolysis. Thus, the folding of nascent proteins, including abnormal ones, may be in kinetic competition with pathways that target these proteins for degradation cotranslationally.     

斑点叉尾鮰IL-22基因克隆及对不同刺激物的响应

为探究白细胞介素-22(interleukin-22,IL-22)基因编码序列(coding sequence,CDS)的分子特征以及在不同病原微生物胁迫下IL-22的响应情况,以斑点叉尾鮰为(Ictalurus punctatus)研究对象,采用PCR扩增技术对该序列进行克隆,通过实时荧光定量PCR(qRT-PCR)方法分析各组织分布以及不同诱导模式下IL-22mRNA表达量的变化情况。结果显示:该序列CDS长度为534 bp,编码177个氨基酸;氨基酸序列多重比对分析发现IL-22在鱼类进化中与脊椎动物保守性较高。qRT-PCR结果显示,IL-22广泛分布在斑点叉尾鮰的10个组织中,表达量在后肠中最高,心脏中最低。Poly(I:C)、LPS、PHA、PMA刺激斑点叉尾鮰肾细胞24～48 h后,Poly(I:C)和LPS刺激下IL-22呈上调反应,PHA、PMA刺激下IL-22呈下调反应;细菌、病毒注射实验以及溴氰菊酯浸泡鱼体的攻毒实验结果显示,鳃、皮肤、后肠、脾脏、中肾和头肾组织中IL-22表达量整体上调。上述结果表明,不同刺激下不同组织中IL-22表达模式具差异性,该基因可能参与...     

果树对盐胁迫的反应及耐盐性鉴定的研究进展

综述了国内外利用盐碱地种植果树的概况 ,不同果树种质资源的耐盐性 ,盐胁迫对果树营养生长及果实品质、生理生化特性的影响及果树耐盐性鉴定的指标     

烟梗浆料蛋白质的酶解研究

[目的]探讨烟梗浆料蛋白质的最佳酶解条件,为造纸法再造烟叶蛋白质的调控提供参考依据.[方法]以红花大金元长梗为试验材料,考察pH、反应温度、绝干浆料质量浓度、粒径、蛋白酶用量及酶解时间6个因素对烟梗浆料蛋白质酶解效果的影响.[结果]烟梗浆料蛋白质的最佳酶解条件为:在pH 6.4~7.2、反应温度35~55℃、粒径≥20目、绝干浆料质量浓度≤2%、中性蛋白酶用量400~800 U/g的条件下酶解2~3 h,烟梗浆料蛋白质的脱除率可达55.70%左右.[结论]在适宜条件下,中性蛋白酶可有效酶解烟梗浆料中的蛋白质.     

Taste stimuli: time course of peripheral nerve response and theoretical models

The responses of a taste nerve in rats to sodium chloride were integrated over successive 10-millisecond intervals and averaged. The time course of the mean responses consisted of a 30-millisecond latency, a rapid rise to a maximum, and a slower decline to a sustained level. The chemoreceptor theories of Beidler and Paton failed to predict the relation between phasic response and time or concentration.     

PBAT地膜降解菌的筛选及其降解特性研究

为了得到能够高效降解聚己二酸/对苯二甲酸丁二酯(PBAT)地膜的菌种资源,以PBAT塑料地膜为主要研究对象,从长期存在塑料的环境中分离筛选塑料降解菌,共得到6株潜在PBAT塑料降解菌,通过对PBAT降解性能进行测定,筛选出两株高效的PBAT降解菌株Pseudomonas sp.RD1-3和Pseudomonas sp.N1-2。在28℃条件下降解8周后,菌株RD1-3和N1-2对PBAT的降解率分别为6.88%±0.06%和6.49%±0.01%。两株菌能使PBAT塑料膜片的表面粗糙程度增加并出现大量沟壑、坑洞及褶皱。此外,两菌株降低了PBAT塑料膜片表面的疏水性,同时向膜片稳定的化学结构中引入—C≡N、—C=C—以及—OH等新的极性官能团。研究初步认定菌株RD1-3以及N1-2对PBAT均具有较好的降解能力。