Gap junction structures: Analysis of the x-ray diffraction data

Models for the spatial distribution of protein, lipid and water in gap junction structures have been constructed from the results of the analysis of X-ray diffraction data described here and the electron microscope and chemical data presented in the preceding paper (Caspar, D. L. D., D. A. Goodenough, L. Makowski, and W.C. Phillips. 1977. 74:605-628). The continuous intensity distribution on the meridian of the X-ray diffraction pattern was measured, and corrected for the effects of the partially ordered stacking and partial orientation of the junctions in the X-ray specimens. The electron density distribution in the direction perpendicular to the plane of the junction was calculated from the meridional intensity data. Determination of the interference function for the stacking of the junctions improved the accuracy of the electron density profile. The pair-correlation function, which provides information about the packing of junctions in the specimen, was calculated from the interference function. The intensities of the hexagonal lattice reflections on the equator of the X-ray pattern were used in coordination with the electron microscope data to calculate to the two-dimensional electron density projection onto the plane of the membrane. Differences in the structure of the connexons as seen in the meridional profile and equatorial projections were shown to be correlated to changes in lattice constant. The parts of the junction structure which are variable have been distinguished from the invariant parts by comparison of the X-ray data from different specimens. The combination of these results with electron microscope and chemical data provides low resolution three- dimensional representations of the structures of gap junctions.     

上海环城林带景观美学评价及优化策略

选取上海环城林带7种植物群落,采用美景度评判法,从林内景观和林外景观2个空间层次和春、夏、秋、冬4个季节,应用数量化理论Ⅰ建立了美景度和各景观因子类目之间的景观评价与预测的多元回归模型,分析了群落的结构特征和季相特征对林内景观以及外貌特征对林外景观的影响,并提出相应的优化对策。结果表明:(1)群落结构特征对林内景观的影响主要因子为胸径(平均胸径和胸径变异系数)、郁闭度和疏透度。在春季,林内美景度随着树木胸径增大而增加;在夏季,郁闭度增大会提升林内美景度;在秋季,胸径变异小的群落具有更高的林内观赏性;在冬季,疏透度对林内景观美景度影响最大。(2)群落季相特征对林内景观的影响,在各季节表现亦不同。在春季,黄色、紫色等明度较高的色相和开花量适中的群落美景度最佳;在夏季,生长势好、林冠层变化小以及树干清晰度高的群落具较高的美景度,且观花可显著提高夏季林内美景度;在秋季,色彩越纯美景度越高;而在冬季,树皮颜色深的群落美景度高。(3)群落外貌特征对林外景观有显著影响,其中林冠线对林外景观美景度影响最大,其次为林缘线。具有起伏不大林冠线和自然流畅林缘线的植物群落美景度高。旨在通过对典型植被群落不同季相的美景度评价,对上海环城林带的群落景观进行定量的评价,进而为不同情景下的群落结构优化提出相应的对策,为城市森林的群落建构与管理提供科学依据。     

120 例初治、年轻、中高/ 高危弥漫大B细胞淋巴瘤的临床分析

目的:探讨初治、年轻、中高/高危弥漫大B细胞淋巴瘤(diffuse large B cell lymphoma,DLBCL)的临床特征、治疗措施及预后影响因素。方法:回顾性分析2006年1月至2014年5月军事医学科学院附属医院淋巴瘤科收治的年龄≤60岁、年龄调整的国际预后指数(aa IPI)评分≥2分的初治DLBCL病例,进行疗效及预后相关因素的分析。结果:共收集到资料完整的DLBCL病例120例,中位随访28(4-106)个月,3年PFS率53.25%,OS率61.52%。单因素分析结果显示B症状、治疗方案及近期疗效、自体移植对无进展生存(PFS)及总体生存(OS)率的影响有统计学意义。多因素分析结果显示治疗方案、自体造血干细胞移植是影响PFS、OS率的独立影响因素。结论:年轻、中高/高危DLBCL具有高度异质性,病理细胞来源、Ki-67等在本组病例中未见显著预后意义,有待临床进一步探索。     

用RACE技术扩增并克隆牛BMP4基因3′端序列

RACE技术是一项扩增基因末端序列的新技术。该研究从牛BMP4基因出发,以牛软骨的RNA为模板,按照不同物种BMP4基因的相似性设计特异引物,运用PCR和RACE技术扩增并获得了特异片段,该片段经PCR、酶切和测序验证,证实所克隆序列为牛BMP4的3′端序列,包含有1170bp组成的开放读码框(ORF),编码389个氨基酸,3′非编码区121bp个核苷酸和poly(A)15。同源性分析结果表明,牛BMP4 cDNA最大开放读码框所推测的氨基酸序列与已知人、小鼠、大鼠、狗、羊和鸡等真核生物BMP4氨基酸序列进行比较,分别有94.5%、93.1%、91.9%、87.4%、94.2%、79%的同源性。这为克隆其他物种的BMP4基因提供了依据,同时牛骨形态发生蛋白的测序为我们更好的理解牛的生骨机理提供帮助。     

产超广谱β- 内酰胺酶肺炎克雷伯菌耐药性及其基因分型分析

目的:了解新疆独山子地区肺炎克雷伯菌超广谱β-内酰胺酶(ESBLs)的发生率、作为指示剂的五种抗生素的检出情况及ESBLs主要基因型。方法:收集临床分离的148株肺炎克雷伯菌,采用双纸片协同筛选法、NCCLS推荐的表型筛选和确证试验对细菌进行ESBLs产酶株的识别;耐药基因的质粒重组、转化,聚合酶链反应(PCR)扩增阳性产物测序,通过GenBank对序确定基因型。结果:本地区肺炎克雷伯菌ESBLs的分离率达31.1%,头孢曲松(CRO)安曲南(ATM)和头孢噻肟(CTX)头孢泊肟(CPD)、头孢他定(CAZ)作为指示剂检出率分别为97.8%、95.6%、93.4%、76.0%、65.2%;本地区产ESBLs菌株耐药基因型CTX-M-22占54.3%,CTX-M-18占41.3%,TEM61.8%,52.1%的产ESBLs肺炎克雷伯菌SHV耐药基因阳性。结论:CRO、ATM和CTX对检测ESBLs阳性率较高;CTX-M-22、CTX-M-18是本地区产ESBLs菌株的主要基因型。     

Bead rings at the endoplasmic reticulum-golgi complex boundary: morphological changes accompanying inihibition of intracellular transport of secretory proteins in arthropod fat body tissue

Golgi complex beads are 10-nm particles arranged in rings on the smooth surface of rough endoplasmic reticulum (ER) makind the forming face of the Golgi complex (GC). In arthropod cells they stain specifically with bismuth. Their morphology has been studied after treatment with reagents known to interfere with GC function. Inhibitors of oxidative phosphorylation (antimycin A, cyanide, and anoxia), but not an inhibitor of glycolysis (iodoacetate), both cause the bead rings to collapse and the GC saccules to round up, and inhibit transition vesicle (TV) formation. Cycloheximide blocks protein synthesis on ribosomes but does not stop TV formation or disrupt bead rings, even after prolonged treatment (6 h) to allow emptying of the rough ER cisternae. Thus the collapse of bead rings is not attributable to inhibition of protein synthesis, and the ring structure of beads does not require continued protein synthesis and secretion for its maintenance. Valinomycin has effects on the GC similar to those of antimycin A, but {"type":"entrez-nucleotide","attrs":{"text":"A23187","term_id":"833253","term_text":"A23187"}}A23187, monensin, and lasalocid do not affect bead ring structure or TV formation. These results are consistent with valinomycin’s secondarily uncoupling mitochondria, which collapses bead rings and prevents TV formation. Thus inhibitors of oxidative phosphorylation do not influence the beads through cation movement. Because mononsin and lasalocid block secretion at the level of the condensing vacuoles, bead rings are not influenced by blocks in secretion distal to them or by the backup of secretory material. These experiments are consistent with inhibitors of oxidative phosphorylation collapsing bead rings by decreasing intracellular ATP. The concomitant block to TV formation and the collapse of bead rings suggests that integrity of the bead rings is essential for the transport of secretory material from the rough ER to the GC.