光合有效辐射与地下水位变化对柽柳属荒漠灌木群落碳平衡的影响

全球气候变化和人类活动的加剧, 正导致古尔班通古特沙漠南缘原始盐生旱生荒漠地区的地下水位发生显著改变。大气污染导致该地区太阳辐射减少。以盐生荒漠建群种多枝柽柳(Tamarix ramosissima)为研究对象, 选择地下水位在2.9-4.5 m波动的典型原始生境, 观测了生长期内光合有效辐射和地下水位变化时的光合作用、蒸腾作用和叶水势等生理活动的季节变化, 调查了根系分布特征; 并利用涡度相关系统测定了生态系统碳水通量, 估算群落碳同化能力、蒸腾耗水量与叶面积指数的季节变化, 旨在揭示光合有效辐射和地下水位等环境因素对柽柳属(Tamarix)荒漠灌木群落光合作用的影响。研究结果表明: 降水造成的潜土层水分状况变化对多枝柽柳的碳平衡没有显著影响。深根系与气孔调节是多枝柽柳碳平衡适应荒漠环境水分状况的两个关键机制。特殊的气孔行为体现了多枝柽柳以高水分消耗为代价将其碳获取最大化的适应对策; 多枝柽柳生理与群落尺度的水分平衡和碳获取均依赖于深根系获取的稳定地下水源, 缓和的地下水位波动将不会扰动其现有的碳/水平衡, 地下水位剧烈下降将危及多枝柽柳的生存。此外, 光合有效辐射是另一个主要影响因素, 与群落碳获取呈显著正相关关系。群落碳同化能力的季节变化是光合有效辐射和地下水位共同影响下光合作用物候学特征的体现。过度开采地下水和直接破坏原生植被的行为, 将会严重地干扰多枝柽柳群落的生存, 进而破坏该区域现有的生态水文过程。     

Endocardial to Myocardial Notch-Wnt-Bmp Axis Regulates Early Heart Valve Development

Endocardial to mesenchymal transformation (EMT) is a fundamental cellular process required for heart valve formation. Notch, Wnt and Bmp pathways are known to regulate this process. To further address how these pathways coordinate in the process, we specifically disrupted Notch1 or Jagged1 in the endocardium of mouse embryonic hearts and showed that Jagged1-Notch1 signaling in the endocardium is essential for EMT and early valvular cushion formation. qPCR and RNA in situ hybridization assays reveal that endocardial Jagged1-Notch1 signaling regulates Wnt4 expression in the atrioventricular canal (AVC) endocardium and Bmp2 in the AVC myocardium. Whole embryo cultures treated with Wnt4 or Wnt inhibitory factor 1 (Wif1) show that Bmp2 expression in the AVC myocardium is dependent on Wnt activity; Wnt4 also reinstates Bmp2 expression in the AVC myocardium of endocardial Notch1 null embryos. Furthermore, while both Wnt4 and Bmp2 rescue the defective EMT resulting from Notch inhibition, Wnt4 requires Bmp for its action. These results demonstrate that Jagged1-Notch1 signaling in endocardial cells induces the expression of Wnt4, which subsequently acts as a paracrine factor to upregulate Bmp2 expression in the adjacent AVC myocardium to signal EMT.     

经阴道彩超在子宫瘢痕处早期妊娠诊断中的应用

目的：探讨经阴道彩色多普勒超声（彩超）在子宫瘢痕处早期妊娠诊断中的应用价值。方法：研究对象为2011年2月．2012年2月我院接诊的26例经手术或病理确诊的子宫瘢痕处早期妊娠患者,回顾性总结了26例患者的经腹及经彩超资料。结果：通过经阴道彩超的图像声像图分析,及其与手术中病理确诊对比。经阴道彩超诊断符合率（96．1％）显著高于经腹部彩超检查诊断符合率（73．1％）（P〈0．05）。从声像图可以将其分为三型,分别为孕囊型、不均质包快型和混合型。其声像图有各自独特的表现,主要区别在于子宫前壁的下段的表现,及周围血流信号的不同。结论：与经腹壁超声相比,经阴道彩超避免了腹部器官的影响,做到无创,快捷,方便,对子宫瘢痕处早期妊娠的诊断有较高的应用价值,值得推广应用。     

Changes of effective gene dispersal distances by pollen and seeds across successive life stages in a tropical tree

Pollen and seed dispersal are the two key processes in which plant genes move in space, mostly mediated by animal dispersal vectors in tropical forests. Due to the movement patterns of pollinators and seed dispersers and subsequent complex spatial patterns in the mortality of offspring, we have little knowledge of how pollinators and seed dispersers affect effective gene dispersal distances across successive recruitment stages. Using six highly polymorphic microsatellite loci and parentage analyses, we quantified pollen dispersal, seed dispersal, and effective paternal and maternal gene dispersal distances from pollen‐ and seed‐donors to offspring across four recruitment stages within a population of the monoecious tropical tree Prunus africana in western Kenya. In general, pollen‐dispersal and paternal gene dispersal distances were much longer than seed‐dispersal and maternal gene dispersal distances, with the long‐distance within‐population gene dispersal in P. africana being mostly mediated by pollinators. Seed dispersal, paternal and maternal gene dispersal distances increased significantly across recruitment stages, suggesting strong density‐ and distance‐dependent mortality near the parent trees. Pollen dispersal distances also varied significantly, but inconsistently across recruitment stages. The mean dispersal distance was initially much (23‐fold) farther for pollen than for seeds, yet the pollen‐to‐seed dispersal distance ratio diminished by an order of magnitude at later stages as maternal gene dispersal distances disproportionately increased. Our study elucidates the relative changes in the contribution of the two processes, pollen and seed dispersal, to effective gene dispersal across recruitment. Overall, complex sequential processes during recruitment contribute to the genetic make‐up of tree populations. This highlights the importance of a multistage perspective for a comprehensive understanding of the impact of animal‐mediated pollen and seed dispersal on small‐scale spatial genetic patterns of long‐lived tree species.     

p38对骨髓间充质干细胞成肌分化作用的研究

目的:以5-氮杂胞苷(5-Aza-CR)诱导骨髓间充质干细胞(MSCs)成肌分化,探讨生肌调控因子中Myf5的表达及信号转导通路p38在此分化过程中的作用.方法:分离、纯化MSCs,以10 μmol/L 5-Aza-CR诱导其向成肌细胞分化,RT-PCR测定Myf5的表达,免疫组化检测肌球蛋白(myosin)的表达,Western-blot检测p38信号通路特异抑制剂SB203580作用前后磷酸化p38的变化.结果:SB203580作用后,Myf5表达由6 h延迟至9 h,诱导12 d部分MSCs表达myosin,18 d表达的数量及程度明显增加;5-Aza-CR诱导后,磷酸化p38蛋白水平较作用前增强,但在SB203580抑制后明显受抑.结论:5-Aza-CR诱导后,MSCs表达生肌调控因子并向成肌细胞分化,p38在此分化过程中起着正向信号转导作用.     

<Emphasis Type="Italic">Gilvimarinus agarilyticus</Emphasis> sp. nov., a new agar-degrading bacterium isolated from the seashore of Jeju Island

An agarolytic bacterium, designated as strain M5c^T, was isolated from sea sand in Jeju Island, Korea. This isolate was Gram-negative, positive for catalase and oxidase, rod and motile by means of monotrichous flagella. Strain M5c^T has translucent or dark ivory colonies, forms a dent on an agar plate under colonies, and grows in the presence of 1–12% (w/v) NaCl and at 10–37°C. This isolate hydrolyzes agar, alginic acid, carboxymethyl (CM)-cellulose and starch. Phylogenetic analysis based on 16S rRNA gene sequences showed that strain M5c^T can be considered as a species within the genus Gilvimarinus, being most closely related to Gilvimarinus chinensis QM42^T, with a 16S rRNA gene sequence similarity of 95.6%. The major cellular fatty acids were C16:1ω7c and/or iso-C15:0 2OH (33.5%), C16:0 (26.5%) and C18:1ω7c (14.1%). The DNA G+C content was 53.8 mol%. Based on these polyphasic data, strain M5c^T should be classified as a novel species, for which the name Gilvimarinus agarilyticus sp. nov. is proposed. The type strain for the novel species is M5c^T (= KCTC 23325^T = NCAIM B 02425^T).     

靶向干扰Chkl增强阿霉素抗人乳腺癌MCF-7/adr细胞的作用机制研究

Chkl的高表达可能是肿瘤对化疗药物的敏感性降低的重要因素之一,本研究的目的是观察siRNA干扰Chk1对人乳腺癌耐药细胞株MCF-7/adr(耐阿霉素)生长及细胞周期的影响,探讨Chk1在乳腺癌细胞耐药中的作用机制。采用RNAi技术抑制MCF-7/adr细胞中Chk1的表达。Westernblot检测转染前后细胞内Chk1蛋白表达情况,经阿霉素作用后,流式细胞术(FCM)检测其细胞周期分布及细胞凋亡率,MTT法检测细胞增殖。Western blot结果显示,Chk1 siRNA转染24h后,MCF-7/adr细胞中Chk1蛋白表达下降了67%,明显低于对照组和空载体转染组(P<0.05)。FCM法检测结果显示,同时,抑制Chk1的表达可解除阿霉素引起的G_2/M期阻滞;使阿霉素诱导的细胞凋亡率由转染前的(5.54±0.15)%上升到(22.24±0.13)%(P<0.05);在阿霉素浓度为0.4mg/L、4mg/L时,细胞的增殖活性分别下降13%、34%。提示siRNA干扰Chk1能够通过调控MCF-7/adr细胞周期及增殖从而增强乳腺癌细胞对阿霉素的敏感性,为临床上克服乳腺癌化疗耐药提供了新的作用靶点。