血管内皮舒张因子在氧自由基所致慢性缺氧大鼠肺内动脉收缩中的作用

以黄嘌岭(X)-黄嘌呤氧化酶(XO)系统产生氧自由基,应用微量生物测定法观察慢性缺氧(5000m,10d)对大鼠氧自由基所致肺内动脉收缩的影响及内皮舒张因子(EDRF)在其中的作用。慢性缺氧大鼠有内皮的肺内动脉环对氧自由基的收缩反应较正常环境中的对照动物明显增强,加入EDRF灭活剂还原型血红蛋白(RHb)后更加显著;而加入超氧化物歧化酶(铜锌SOD)后则减弱,甚至消除。反之,不论加入RHb或SOD对氧自由基所致去内皮肺内动脉环的收缩反应均无明显影响。上述结果表明慢性缺氧引起肺内动脉收缩增强与EDRF有密切关系:慢性缺氧可能使EDRF的作用减弱,肺内动脉对氧自由基的反应性增强。表示EDRF及其与氧自由基的关系在慢性缺氧性肺动脉高压的形成中可能具有十分重要的意义。     

Large-scale purification,dissociation and functional reassembly of the maltose ATP-binding cassette transporter (MalFGK(2)) of Salmonella typhimurium

The maltose ATP-binding cassette (ABC) transporter of Salmonella typhimurium is composed of a membrane-associated complex (MalFGK(2)) and a periplasmic substrate binding protein. To further elucidate protein-protein interactions between the subunits, we have studied the dissociation and reassembly of the MalFGK(2) complex at the level of purified components in proteoliposomes. First, we optimized the yield in purified complex protein by taking advantage of a newly constructed expression plasmid that carries the malK, malF and malG genes in tandem orientation. Incorporated in proteoliposomes, the complex exhibited maltose binding protein/maltose-dependent ATPase activity with a V(max) of 1.25 micromol P(i)/min/mg and a K(m) of 0.1 mM. ATPase activity was sensitive to vanadate and enzyme IIA(Glc), a component of the enterobacterial glucose transport system. The proteoliposomes displayed maltose transport activity with an initial rate of 61 nmol/min/mg. Treatment of proteoliposomes with 6.6 M urea resulted in the release of medium-exposed MalK subunits concomitant with the complete loss of ATPase activity. By adding increasing amounts of purified MalK to urea-treated proteoliposomes, about 50% of vanadate-sensitive ATPase activity relative to the control could be recovered. Furthermore, the phenotype of MalKQ140K that exhibits ATPase activity in solution but not when associated with MalFG was confirmed by reassembly with MalK-depleted proteoliposomes.     

Novel missense mutations that affect the transport function of MalK, the ATP-binding-cassette subunit of the Salmonella enterica serovar typhimurium maltose transport system

We report on novel mutations in the malK gene of Salmonella enterica serovar Typhimurium, encoding the ATPase subunit of the maltose transporter (MalFGK(2)). Biochemical analysis suggests that (i) L86 might be involved in a signaling step during substrate translocation and (ii) E306 may be critical for the structural integrity of the protein.     

Interactions between neurons and their targets during in vivo synaptogenesis.

In vivo synaptogenesis is described in a simple vertebrate system, the chick ciliary ganglion, a parasympathetic autonomic ganglion. An attempt is made to integrate anatomical, physiological and biochemical observations during synapse formation in the ganglion and in the peripheral target structures; the iris, ciliary muscle, and smooth muscle of the choroid coat. The relationship between synaptogenesis and neuron survival is explored, and it is shown that a critically timed interaction between the neuron and target organ is necessary for full neuronal maturation and survival. The existence of an active competition between neurons for survival is documented, and the possible relationship between neuronal cell death and specificity of connections is discussed.     

MPDA: Microarray pooled DNA analyzer

Background  

Microarray-based pooled DNA experiments that combine the merits of DNA pooling and gene chip technology constitute a pivotal advance in biotechnology. This new technique uses pooled DNA, thereby reducing costs associated with the typing of DNA from numerous individuals. Moreover, use of an oligonucleotide gene chip reduces costs related to processing various DNA segments (e.g., primers, reagents). Thus, the technique provides an overall cost-effective solution for large-scale genomic/genetic research. However, few publicly shared tools are available to systematically analyze the rapidly accumulating volume of whole-genome pooled DNA data.     

三苯基锡,二环己基碳二亚胺和寡霉素对叶绿体CF0与CF1功能联系的影响

作用于H~ —ATP酶复合体质子通道的能量传递抑制剂 TPT、DQCD和 OM能明显抑制叶绿体光合磷酸化反应和膜上 ATP酶活性,减小恒态ΛpH值,加速ΛpH和515 nm吸收衰减。这种在正常叶绿体加速H_(in)~ 经CF_0外流与在残缺膜中阻塞质子外流不一致。TPT等物质是干扰了CF_0与CF_1的构象连接,使 CF_0的质子传导失去CF_1的控制,H_(in)~ 无效漏失或质子逆向转移受影响,从而抑制与质子传导紧密相关的光合磷酸化反应和膜上ATP酶活性。     

Relationship of primary and secondary myogenesis to fiber type development in embryonic chick muscle.

The formation of fast and slow myotubes was investigated in embryonic chick muscle during primary and secondary myogenesis by immunocytochemistry for myosin heavy chain and Ca2(+)-ATPase. When antibodies to fast or slow isoforms of these two molecules were used to visualize myotubes in the posterior iliotibialis and iliofibularis muscles, one of the isoforms was observed in all primary and secondary myotubes until very late in development. In the case of myosin, the fast antibody stained virtually all myotubes until after stage 40, when fast myosin expression was lost in the slow myotubes of the iliofibularis. In the case of Ca2(+)-ATPase, the slow antibody also stained all myotubes until after stage 40, when staining was lost in secondary myotubes and in the fast primary myotubes of the posterior iliotibialis and the fast region of the iliofibularis. In contrast, the antibodies against slow muscle myosin heavy chain and fast muscle Ca2(+)-ATPase stained mutually exclusive populations of myotubes at all developmental stages investigated. During primary myogenesis, fast Ca2(+)-ATPase staining was restricted to the primary myotubes of the posterior iliotibialis and the fast region of the iliofibularis, whereas slow myosin heavy chain staining was confined to all of the primary myotubes of the slow region of the iliofibularis. During secondary myogenesis, the fast Ca2(+)-ATPase antibody stained nearly all secondary myotubes, while primaries in the slow region of the iliofibularis remained negative. Thus, in the slow region of the iliofibularis muscle, these two antibodies could be used in combination to distinguish primary and secondary myotubes. EM analysis of staining with the fast Ca2(+)-ATPase antibody confirmed that it recognizes only secondary myotubes in this region. This study establishes that antibodies to slow myosin heavy chain and fast Ca2(+)-ATPase are suitable markers for selective labeling of primary and secondary myotubes in the iliofibularis; these markers are used in the following article to describe and quantify the effects that chronic blockade of neuromuscular activity or denervation has on these populations of myotubes.     

大菜粉蝶颗粒体病毒的研究:包含体结合的碱性蛋白酶

本文报道从新疆分离的一株大菜粉蝶(Pieris brassicae)颗粒体病毒(PbGV)包含体上结合有碱性蛋白酶.提取含酶的包含体蛋白,以酪蛋白为底物鉴定表明此酶在pH9.4有最大的酶活力,并定位于“包裹”在病毒粒子套膜外的包含体蛋白中.在高pH时分子皿为26,500的包含体蛋白被酶降解为19,500和15,600道尔顿的两个组分.Hg⁺⁺、Cu⁺⁺仅部分抑制酶活力,可被二异丙基氟磷酸(DFP)完全抑制.75℃以上加热处理可使酶失活,并大大降低病毒包含体的解离.推测此酶是影响PbGV对寄主感染率的因子之一.     

The regulation of intramuscular nerve branching during normal development and following activity blockade

In vertebrates, approximately 50% of the lumbosacral motoneurons die during a short period of development that coincides with synaptogenesis in the limb. Although it has been postulated that these motoneurons die because they fail to obtain adequate trophic support from the muscles, it is not clear how this factor is supplied. The mechanism by which activity blockade prevents motoneurons cell death is also unknown. In order to begin to understand the nature of these proposed trophic interactions, we have examined the temporal sequence of axonal invasion and ramification within two muscles of the chick hindlimb, the predominantly slow iliofibularis and the fast posterior iliotibialis, during the cell death period. We found striking differences in intramuscular nerve ingrowth and branching between fast and slow muscle. We also observed differences in the molecular composition of fast and slow myotubes that may contribute to the nerve pattern differences. In addition, we observed a progressive increase in the degree of intramuscular nerve fasciculation as well as a precise temporal sequence of nerve branching. The earliest detectable response to chronic curarization was a dramatic decrease in the degree of intramuscular nerve fasciculation. Activity blockade also greatly enhanced nerve branching within the muscles from the time that nerve branches normally formed, and, additionally, interfered with the normal cessation of axon growth. Our results support the idea that nerve endings are the sites of trophic uptake. Furthermore, although our results do not allow us to exclude other activity-dependent influences on motoneuron survival, they suggest the following testable hypotheses: (1) the normal regulation of motoneuron survival may result from the precise control of intramuscular nerve branching, (2) activity blockade may increase motoneuron survival by enhancing intramuscular nerve branching, and (3) anything which affects this complex process of nerve branching may also alter motoneuron survival.