An age-induced switch to a hyper-recombinational state

There is a strong correlation between age and cancer, but the mechanism by which this phenomenon occurs is unclear. We chose Saccharomyces cerevisiae to examine one of the hallmarks of cancer--genomic instability--as a function of cellular age. As diploid yeast mother cells aged, an approximately 100-fold increase in loss of heterozygosity (LOH) occurred. Extending life-span altered neither the onset nor the frequency of age-induced LOH; the switch to hyper-LOH appears to be on its own clock. In young cells, LOH occurs by reciprocal recombination, whereas LOH in old cells was nonreciprocal, occurring predominantly in the old mother's progeny. Thus, nuclear genomes may be inherently unstable with age.     

高职高专新进教师如何快速实现角色转换

新进教师在教学水平等方面能力都相对较低,如何在短时间内适应工作岗位需要,实现角色转换成为他们迫切的需要。要在积极参加岗前培训的基础上,注重培养教学基本功,加强生产实践锻炼,注重科研与教学相结合。     

Urinary adenosine 3',5'-monophosphate in the switch process from depression to mania

Marked elevations of urinary adenosine 3',5'-monophosphate occurred on the day of rapid switch from a depressed into a manic state in patients with manic-depressive illness. It is suggested that this increase might serve a trigger function for the process by which catecholamines are elevated during the manic phase of the illness.     

SRC mediates a switch from microtubule- to actin-based motility of vaccinia virus

The cascade of events that leads to vaccinia-induced actin polymerization requires Src-dependent tyrosine phosphorylation of the viral membrane protein A36R. We found that a localized outside-in signaling cascade induced by the viral membrane protein B5R is required to potently activate Src and induce A36R phosphorylation at the plasma membrane. In addition, Src-mediated phosphorylation of A36R regulated the ability of virus particles to recruit and release conventional kinesin. Thus, Src activity regulates the transition between cytoplasmic microtubule transport and actin-based motility at the plasma membrane.     

无线遥控变压器保护开关的制作

无线遥控以其传输距离远、抗干扰能力强、无方向性等优点,被应用于许多领域。本文详细介绍了以小型无线遥控发射模块TWH9236和无线接收模块TWH9238作为遥控开关的执行元件取代了保护变压器的断路器手动合闸手柄,使产品具有操作方便、可靠性、保密性强等优点,提高了产品档次,增加了该产品的市场竞争力。     

Intramembrane cleavage of AMA1 triggers Toxoplasma to switch from an invasive to a replicative mode

Apicomplexan parasites invade host cells and immediately initiate cell division. The extracellular parasite discharges transmembrane proteins onto its surface to mediate motility and invasion. These are shed by intramembrane cleavage, a process associated with invasion but otherwise poorly understood. Functional analysis of Toxoplasma rhomboid 4, a surface intramembrane protease, by conditional overexpression of a catalytically inactive form produced a profound block in replication. This was completely rescued by expression of the cleaved cytoplasmic tail of Toxoplasma or Plasmodium apical membrane antigen 1 (AMA1). These results reveal an unexpected function for AMA1 in parasite replication and suggest that invasion proteins help to promote parasite switch from an invasive to a replicative mode.     

Structure of the nucleotide activation switch in glycogen phosphorylase a

Adenosine monophosphate is required for the activation of glycogen phosphorylase b and for release of the inhibition of phosphorylase a by glucose. Two molecules of adenosine monophosphate (AMP) bind to symmetry related sites at the subunit interface of the phosphorylase dimer. Adenosine triphosphate (ATP) binds to the same site, but does not promote catalytic activity. The structure of glucose-inhibited phosphorylase a bound to AMP and also of the complex formed with glucose and ATP is described. Crystallographic refinement of these complexes reveals that structural changes are associated with AMP but not ATP binding. The origin of these effects can be traced to different effector binding modes exhibited by AMP and ATP, respectively. The conformational changes associated with AMP binding traverse multiple paths in the enzyme and link the effector and catalytic sites.     

京郊高产高效种植模式的研究

作者对北京郊区自然资源和传统的高效种植方式进行了广泛调查、通过要素分解和田间量化试验，组装了７大类２５种适合京郊地区不同区域推广应用的高产高效种植模式，建立了与高效种植模式相配套的优良品种资源库及相配套的生产技术规程，组建了一个覆盖京郊种植业的技术推广体系网络，建成了一批高产高效种植模式中心示范区，形成了一批有特色的、具有一定规模的高效益模式种植区域。     

Two-amino acid molecular switch in an epithelial morphogen that regulates binding to two distinct receptors

Ectodysplasin, a member of the tumor necrosis factor family, is encoded by the anhidrotic ectodermal dysplasia (EDA) gene. Mutations in EDA give rise to a clinical syndrome characterized by loss of hair, sweat glands, and teeth. EDA-A1 and EDA-A2 are two isoforms of ectodysplasin that differ only by an insertion of two amino acids. This insertion functions to determine receptor binding specificity, such that EDA-A1 binds only the receptor EDAR, whereas EDA-A2 binds only the related, but distinct, X-linked ectodysplasin-A2 receptor (XEDAR). In situ binding and organ culture studies indicate that EDA-A1 and EDA-A2 are differentially expressed and play a role in epidermal morphogenesis.