Impaired degradation of mutant alpha-synuclein by chaperone-mediated autophagy

Aberrant alpha-synuclein degradation is implicated in Parkinson's disease pathogenesis because the protein accumulates in the Lewy inclusion bodies associated with the disease. Little is known, however, about the pathways by which wild-type alpha-synuclein is normally degraded. We found that wild-type alpha-synuclein was selectively translocated into lysosomes for degradation by the chaperone-mediated autophagy pathway. The pathogenic A53T and A30P alpha-synuclein mutants bound to the receptor for this pathway on the lysosomal membrane, but appeared to act as uptake blockers, inhibiting both their own degradation and that of other substrates. These findings may underlie the toxic gain-of-function by the mutants.     

Yeast cells provide insight into alpha-synuclein biology and pathobiology

Alpha-synuclein is implicated in several neurodegenerative disorders, such as Parkinson's disease and multiple system atrophy, yet its functions remain obscure. When expressed in yeast, alpha-synuclein associated with the plasma membrane in a highly selective manner, before forming cytoplasmic inclusions through a concentration-dependent, nucleated process. Alpha-synuclein inhibited phospholipase D, induced lipid droplet accumulation, and affected vesicle trafficking. This readily manipulable system provides an opportunity to dissect the molecular pathways underlying normal alpha-synuclein biology and the pathogenic consequences of its misfolding.     

侧柏球花的发端发育及物候学

侧柏营养技端4月下旬萌动,5～10月为营养生长期,10月以后休眠。7月中旬至8月上旬,长日照中日照惭短的时期,营养枝端转化为生殖枝端。雄球花端圆球形,雌球花端圆柱状。8～10月为球花发育期,10月进入休眠。翌年3月末传粉受精,10月初球果成熟。成熟的雌球花枝较雄球花枝长,90°弯曲。雌球花数量少,多着生在当年生枝条基部近轴面的侧枝上。对侧柏球花发端的时间、特点和其他针叶树种进行比较与讨论。     

蛋白质翻译起始因子的作用与调控

 蛋白质翻译起始因子是一类在真核细胞中蛋白质翻译所必需的、保证正确的mRNA－核糖体复合物形成的蛋白质,已知的起始因子共有12种,在真核细胞翻译起始阶段有重要作用。蛋白质合成的调节主要通过翻译起始因子的磷酸化进行。真核细胞蛋白质翻译最重要的调节位点是翻译起始因子eIF 2和eIF 4。本文主要综述了近年来关于蛋白质翻译起始因子的作用及调控的最新研究进展     

银杏硬枝扦插与器官发生

3月上中旬,用10年生和30年生银杏母树1～2年生枝条为插穗,细砂土作扦插基质,采用荫棚加地膜的硬枝扦插,平均生根率45％以上。10年生幼树枝比30年生结果树枝条生根率高。银杏属愈伤组织生根类型,生根时间相对较长。     

Differential regulation of dynein and kinesin motor proteins by tau

Dynein and kinesin motor proteins transport cellular cargoes toward opposite ends of microtubule tracks. In neurons, microtubules are abundantly decorated with microtubule-associated proteins (MAPs) such as tau. Motor proteins thus encounter MAPs frequently along their path. To determine the effects of tau on dynein and kinesin motility, we conducted single-molecule studies of motor proteins moving along tau-decorated microtubules. Dynein tended to reverse direction, whereas kinesin tended to detach at patches of bound tau. Kinesin was inhibited at about a tenth of the tau concentration that inhibited dynein, and the microtubule-binding domain of tau was sufficient to inhibit motor activity. The differential modulation of dynein and kinesin motility suggests that MAPs can spatially regulate the balance of microtubule-dependent axonal transport.     

南瓜实蝇在杭州地区的种群消长动态

南瓜实蝇[Bactrocera tau(Walker)]是瓜果类蔬菜的一种危险性害虫。以诱虫酮(cuelure)作为诱剂对杭州地区南瓜实蝇成虫的发生动态进行了监测。结果表明,南瓜实蝇成虫于5月上旬至6月上旬开始活动,7月中旬至9月下旬为成虫的活动高峰期,10月以后成虫活动明显减少,11月以后很难诱集到成虫。对该虫活动规律、在浙江的越冬虫态、发生代数进行讨论。     

玉米自交系愈伤组织的诱导及再生

利用黑龙江省生产上大面积使用的8个优良玉米自交系的幼胚为外植体诱导愈伤组织，研究了基因型和2，4－D浓度对愈伤组织诱导的影响。结果表明：玉米的组织培养对基因型的依赖性较强；愈伤诱导阶段需要较高的2，4－D浓度，继代过程中要根据愈伤组织的生长情况及时调整2，4－D浓度。同时对影响玉米愈伤组织的分化、植株再生及其移植的因素进行了分析。     

Chaperone suppression of alpha-synuclein toxicity in a Drosophila model for Parkinson's disease

Parkinson's disease is a movement disorder characterized by degeneration of dopaminergic neurons in the substantia nigra pars compacta. Dopaminergic neuronal loss also occurs in Drosophila melanogaster upon directed expression of alpha-synuclein, a protein implicated in the pathogenesis of Parkinson's disease and a major component of proteinaceous Lewy bodies. We report that directed expression of the molecular chaperone Hsp70 prevented dopaminergic neuronal loss associated with alpha-synuclein in Drosophila and that interference with endogenous chaperone activity accelerated alpha-synuclein toxicity. Furthermore, Lewy bodies in human postmortem tissue immunostained for molecular chaperones, also suggesting that chaperones may play a role in Parkinson's disease progression.     

Stomatal patterning and differentiation by synergistic interactions of receptor kinases

Coordinated spacing and patterning of stomata allow efficient gas exchange between plants and the atmosphere. Here we report that three ERECTA (ER)-family leucine-rich repeat-receptor-like kinases (LRR-RLKs) together control stomatal patterning, with specific family members regulating the specification of stomatal stem cell fate and the differentiation of guard cells. Loss-of-function mutations in all three ER-family genes cause stomatal clustering. Genetic interactions with a known stomatal patterning mutant too many mouths (tmm) revealed stoichiometric epistasis and combination-specific neomorphism. Our findings suggest that the negative regulation of ER-family RLKs by TMM, which is an LRR receptor-like protein, is critical for proper stomatal differentiation.     

增效型螯合肥对小麦生长和产量的影响

为探究海藻酸增效剂对螯合肥的增效作用,以小麦为研究对象,进行了增效型螯合肥对小麦生长及产量的影响试验。结果表明,与普通复合肥相比,不同螯合肥处理小麦产量显著提高,在德州以增效螯合肥2处理增产率最高,达到16.5%,较普通螯合肥增产2.5%;在平原以增效螯合肥2处理增产率最高,达到12.5%,较普通螯合肥增产2.0%,增效螯合肥1与原配方相比,基本不减产。添加海藻酸增效剂对小麦株高、茎粗、生物量等均具有较好的促进作用,与普通复合肥相比,地上部干重增幅分别为0.5%～35.4%(德州)、11.6%～58.0%(平原),地下部干重增幅分别为23.1%～64.7%(德州)、8.9%～54.1%(平原)。由此表明,添加海藻酸增效剂可以促进小麦前期营养生长,提高作物抗逆性,提高产量。本试验条件下,以1%添加量最佳,且添加海藻酸增效剂后,可达到减肥增效的目的。     

哺乳动物原始卵泡启动和生长的调控机理

从卵泡生长启动的早期指标、调控原始卵泡生长启动的因素等方面综述调控原始卵泡生长启动相关因子的最新进展。     

棒料塑性剪切过程中裂纹的形成及扩展行为

通过轴向压力作用下棒料塑性切口工试验，获取了剪切分离面上断裂区形态，结果表明：断裂区呈对称月牙状，断裂面积比率随轴向压力的增大而减小。结合理论分析，提示了剪切过程中裂纹首先产生于棒料上活动剪刃与固定剪刃交叉的两水平端点，并沿活动剪刃和固定剪刃刃口迹线扩展。裂纹为Ⅱ、Ⅲ型的混合型，其中Ⅲ型裂纹扩展速度对于断裂区形态起着决定作用。     

The primary structure and heterogeneity of tau protein from mouse brain

Tau protein is a family of microtubule binding proteins, heterogeneous in molecular weight, that are induced during neurite outgrowth and are found prominently in neurofibrillary tangles in Alzheimer's disease. The predicted amino acid sequences of two forms of tau protein from mouse brain were determined from complementary DNA clones. These forms are identical in their amino-terminal sequences but differ in their carboxyl-terminal domains. Both proteins contain repeated sequences that may be tubulin binding sites. The sequence suggests that tau is an elongated molecule with no extensive alpha-helical or beta-sheet domains. These complementary DNAs should enable the study of various functional domains of tau and the study of tau expression in normal and pathological states.     

Initiation of angiogenesis by human follicular fluid

Angiogenesis was observed and measured after injection of human follicular fluid into rabbit corneas. Undiluted human follicular fluid stimulated angiogenesis in every case, with new blood vessels visible 3 days after injection and extending 2.0 millimeters from the corneal scleral limbus into the injection site by day 15. Stimulation of angiogenesis was lost by heating or diluting the follicular fluid but was retained after charcoal stripping or dialysis. Human follicular fluid contains an angiogenic factor that may be associated with perifollicular neovascularization during folliculogenesis.     

影响口蹄疫病毒转译起始的因素

口蹄疫病毒的转译起始由一基因组内的顺式作用元件被称为内部核糖进入位点(IRES)所介导.FM DV的IRES的二级结构、三级结构以及它们之间的相互作用,是维持其转译活性所必需的.在这个转译过程中。E IF 4G,E IF 4B,E IF 4A协同的结合到IRES的3'区域,然后小核糖体亚单位、大核糖体亚单位结合到连有起始因子的IRES复合物上,核糖体在小RNA的IRES上得到组装,转译开始。     

Initiation of Setaria as a model plant

Model organisms such as Arabidopsis (Arabidopsis thaliana) and rice (Oryza sativa) have proven essential for efficient scientific discovery and development of new methods. With the diversity of plant lineages, some important processes such as C₄ photosynthesis are not found in either Arabidopsis or rice, so new model species are needed. Due to their small diploid genomes, short life cycles, self-pollination, small adult statures and prolific seed production, domesticated foxtail millet (Setaria italica) and its wild ancestor, green foxtail (S. viridis), have recently been proposed as novel model species for functional genomics of the Panicoideae, especially for study of C₄ photosynthesis. This review outlines the development of these species as model organisms, and discusses current challenges and future potential of a Setaria model.