Characterization of mutations in the two-component histidine kinase gene that confer fludioxonil resistance and osmotic sensitivity in the os-1 mutants of Neurospora crassa

Osmotic-sensitive (os-1) mutant alleles in Neurospora crassa exhibit resistance to dicarboximides, aromatic hydrocarbons and phenylpyrroles. We have previously reported that the os-1 mutants can be classified into two groups based on their resistance to fungicides and osmotic stress: type I, which are highly resistant to iprodione and fludioxonil but moderately sensitive to osmotic stress, and type II, which are highly sensitive to osmotic stress but moderately resistant to fungicides. To explain the mechanism of resistance to these fungicides, we cloned and sequenced the mutant os-1 genes that encode putative osmo-sensing histidine kinase. Within the os-1 gene product (Os1p), the type I strains, NM233t and Y256M209, carried a stop codon at amino acid position 308 and a frameshift at amino acid position 294, respectively. These mutation sites were located on the upstream of histidine kinase and the response regulator domains of Os1p, strongly suggesting that type I strains are null mutants. The null mutants, NM233t and Y256M209, were highly resistant to iprodione and fludioxonil; thus Os1p is essential for these fungicides to express their antifungal activity. The amino acid changes in Os1p, 625Pro from Leu, 578Val from Ala, and 580Arg from Gly were found in the type II strains, M16, M155-1 and P5990, respectively. Os1p is novel in having six tandem repeats of 90 amino acids in the N terminal. Each amino acid change of the type II strains was located on the fifth unit of six tandem repeats. Type II strains with single amino acid changes were more sensitive to osmotic stress than the null mutants (type I), indicating that the amino acid repeats of Os1p were responsible for an important function in osmo-regulation.     

荔枝霜疫霉中双组分信号转导系统的鉴定与表达分析

 荔枝霜疫霉(Peronophythora litchii)隶属于茸鞭生物界卵菌门疫霉属,由其引起的荔枝霜疫病是目前荔枝生产上一种最重要的病害,严重影响荔枝产量和鲜果品质。双组分信号途径在微生物中参与多种生命活动,但是在卵菌中尚未有相关研究。本研究通过生物信息学分析在荔枝霜疫霉中鉴定到2个杂合型组氨酸激酶(PlHK1、PlHK2)和1个响应调控蛋白(PlRR1)。其在卵菌中是保守存在的,并且与真菌在进化上相对独立。功能域分析表明,PlHK1和PlHK2的C端额外的融合了1个磷酸转移功能域(Hpt),这与真菌和植物的存在显著差异。转录分析表明3个基因在荔枝霜疫霉侵染阶段上调表达,并且响应渗透胁迫和氧化胁迫。以上结果揭示了双组分信号系统可能在疫霉致病过程中发挥重要作用。     

支链氨基酸对mRNA翻译起始的调控作用

综述了支链氨基酸(BCAAS)对mRNA翻译起始过程的调控及其在调控过程中信号转导机制方面的研究进展,包括翻译的起始过程,BCAAs对翻译起始过程的调节和BCAAs在调节起始过程中的信号转导机制,并就值得深入研究的问题进行了探讨。     

炎症标志物抵抗素研究进展

抵抗素是一种与肥胖以及肥胖相关疾病密切相关的脂肪细胞因子.近年研究表明,该因子参与炎症的发生过程.文章从抵抗素与炎症因子和C反应蛋白的相关性,与内皮细胞的相互作用以及炎症相关的临床和试验研究几个方面阐述了抵抗素与炎症的关系.     

校园视频直播系统的设计与实现

很多学校经常举办大型的会议、论坛、名人讲座和文艺汇演,由于参加人数众多,经常会出现会议场地不够的情况.因此,建立规模适度、经济可行且先进可靠的校园视频直播系统是各学校都在寻求的解决方案.本文从实际出发来探讨校园视频直播系统的设计与实现.     

缺铁黄瓜地上部对根系适应性反应的调节

用营养液培养方法研究了黄瓜地上部对根系缺铁适应性反应的调节。缺铁导致植株根系Fe     

绵羊妊娠识别、建立和维持的信号系统

妊娠的建立和维持归因于胚体的信号和黄体对孕酮的产生,在反刍动物,胚体滋养层分泌的激素抑制子宫内膜产生前列腺素PGF2α。在发情周期的绵羊,孕酮下调子宫内膜腔上皮和子宫腺上皮孕酮受体基因的表达,并伴随着上皮雌激素受体和催产素受体的增加。在催产素的作用下,子宫开始分泌溶黄体作用的前列腺素F2α。在妊娠绵羊,孕体滋养层产生的干扰素可作用于子宫内膜而直接抑制雌激素受体基因和催产素受体基因的转录。孕酮、干扰素、胎盘催乳素和生殖激素共同组成了一个"作用网络"来调节子宫的功能分化和子宫腺的形态发生,从而维持绵羊妊娠。本文综述了绵羊妊娠识别、建立和维持的信号系统。     

活性氧和一氧化氮在植物——病原体互作反应中的作用

植物被病原体感染后，植物体内活性氧产量急剧增加，这一现象被称为氧爆。活性氧族包括如单线态氧1O2、超氧阴离子自由基O2-.、氢过氧自由基HO2·、过氧化氢H2O2、羟自由基·OH等。与ROS关系密切的一氧化氮，属于活性氮族。ROS和NO参与植物生长发育调控和对环境胁迫的应答反应，特别是在对抗外来病原体的入侵的防卫过程中发挥了重要作用。本文主要讨论ROS和NO在植物与病原体相互作用中发挥的作用。     

利用仿真技术对数字信号处理教学改革的研究

以巴特沃斯滤波器设计为例,论述了MATLAB编程、信号处理工具箱等计算机仿真手段在数字信号处理教学中的应用,分析了数字信号处理与模拟电子技术等先修课程的内在联系。仿真技术的引入,使抽象复杂的数字信号处理理论具体化,从而降低了学生理解知识的难度,收到了很好的教学效果。