濒危植物西康玉兰种子休眠、萌发及贮藏特性

研究了西康玉兰(Magnolia wilsonii)种胚的形态大小,温度、层积、硝酸钾、浸种处理和GA_3对种子休眠及萌发的影响.通过将种子脱水至不同含水量和在两种温度(4℃和一20℃)下贮藏100 d后测其生活力,分析各处理对西康玉兰种子活力的影响.结果表明:西康玉兰种子胚尚未分化完全,需经过低温层积完成生理后熟;低温层积和GA3可打破种子休眠.种子最适萌发温度为25/20℃.由此推测,西康玉兰种子具有形态生理休眠特性.西康玉兰种子当含水量降至5.39%,存活率为53.50%.不同含水量的种子贮藏在-20℃条件下,100 d后种子全部死亡;但在4℃下含水量为10.31%的种子存活力高达76%.因此,西康玉兰种子极可能属于中间性种子,其适宜贮藏环境为4℃下的干藏或湿藏.     

MRSA感染性创面菌群结构分析

目的探究耐甲氧西林金黄色葡萄球菌(MRSA)感染性创面与创面旁菌种组成的差异并寻找可能的有益菌,为从皮肤微生态角度治疗MRSA感染性创面提供理论依据。方法采集湖南省人民医院MRSA感染性创面及创面旁的皮肤样本,其中创面部位样本22份为D组,创面旁样本11份为N组,提取样本DNA,采用高通量测序技术对16S rRNA基因V3-V4区测序并进行生物信息学分析。结果根据Alpha多样性分析,D组的Chao1指数、Ace指数和Shannon指数明显低于N组(Z=62, P=0.023 8；Z=66, P=0.035 9；Z=30, P=0.000 2),而Simpson指数明显高于N组(Z=211, P=0.000 3)。Beta多样性分析显示2组皮肤菌群组成具有差异,表明分组合理(R=0.584 3、0.467 3, P=0.001 0)。D组葡萄球菌属(Staphylococcus)及韦荣球菌属(Veillonella)丰度显著性升高(Z=213, P=0.000 5；Z=48.5, P=0.004 8),其他常驻菌群均下降。N组的乳杆菌属(Lactobacillus)相对丰度均值较D组高(Z=38, P=0.000 8)。结论MRSA感染性创面的菌群结构较创面旁组具有一定变化,Lactobacillus为皮肤有益菌,可能对创面的恢复有益。     

Ocean acidification and warming will lower coral reef resilience

Ocean warming and acidification from increasing levels of atmospheric CO₂ represent major global threats to coral reefs, and are in many regions exacerbated by local‐scale disturbances such as overfishing and nutrient enrichment. Our understanding of global threats and local‐scale disturbances on reefs is growing, but their relative contribution to reef resilience and vulnerability in the future is unclear. Here, we analyse quantitatively how different combinations of CO₂ and fishing pressure on herbivores will affect the ecological resilience of a simplified benthic reef community, as defined by its capacity to maintain and recover to coral‐dominated states. We use a dynamic community model integrated with the growth and mortality responses for branching corals (Acropora) and fleshy macroalgae (Lobophora). We operationalize the resilience framework by parameterizing the response function for coral growth (calcification) by ocean acidification and warming, coral bleaching and mortality by warming, macroalgal mortality by herbivore grazing and macroalgal growth via nutrient loading. The model was run for changes in sea surface temperature and water chemistry predicted by the rise in atmospheric CO₂ projected from the IPCC's fossil‐fuel intensive A1FI scenario during this century. Results demonstrated that severe acidification and warming alone can lower reef resilience (via impairment of coral growth and increased coral mortality) even under high grazing intensity and low nutrients. Further, the threshold at which herbivore overfishing (reduced grazing) leads to a coral–algal phase shift was lowered by acidification and warming. These analyses support two important conclusions: Firstly, reefs already subjected to herbivore overfishing and nutrification are likely to be more vulnerable to increasing CO₂. Secondly, under CO₂ regimes above 450–500 ppm, management of local‐scale disturbances will become critical to keeping reefs within an Acropora‐rich domain.     

Longitudinal Water Movement in the Primary Root of Zea mays

The rates of transfer of tritiated water (THO) along lengthsof excised primary roots of Zea mays have been measured undera variety of conditions. The following values of ‘apparentdiffusion coefficients’ for THO in the root tissue havebeen evaluated: 1.5±0.1x10^-5 cm² sec^-1 in roots boiledfor 3 min before use,0.5±0.03x10^-5 cm² sec^-1 in rootspoisoned with 10^-2 M NaF,0.9±0.07x10^-5 cm² sec^-1 in rootspoisoned with 10^-2 M NaN₃,and 2.1±0.2x10^-5 cm² sec^-1in normal roots. The bathing medium in all cases was 1.0 mMKCl/0.1 mM CaCl₂ with the addition of the inhibitors where appropriate.Thefourfold increase in the rate of THO transfer in normal rootscompared with poisoned ones is attributed to the existence ofa long-distance convective flow in the first case, which isterminated by the addition of inhibitors. Since experimentsshow that this convective flow must occur both acropetally andbasipetally with equal velocity, it is thought to occur in thephloem.By assuming the ‘streaming transcellular strands’model for phloem transport, the rate of movement required togive the observed transfer has been computed as approximately4.5x10^-2 cm sec^-1 (160 cm h^-1).The earlier report of the existenceof a highly impermeable barrier surrounding the xylem vesselshas been further substantiated by the experiments reported here.     

Scale‐dependent processes of community assemblyin an African rift lake

1. Ecologists continue to debate whether the assembly of communities of species is more strongly influenced by dispersal limitations or niche‐based factors. Analytical approaches that account for both mechanisms can help to resolve controls of community assembly. 2. We compared littoral snail assemblages in Lake Tanganyika at three different spatial scales (5–25 m, 0.5–10 km and 0.5–27 km) to test whether spatial distance or environmental differences are better predictors of community similarity. 3. At the finest scale (5–25 m), snail assemblages shifted strongly with depth but not across similar lateral distances, indicating a stronger response to environmental gradients than dispersal opportunities. 4. At the two larger scales (0.5–27 km), both environmental similarity and shoreline distance between sites predicted assemblage similarity across sites. Additionally, canonical correspondence analysis revealed that snail abundances were significantly correlated with algal carbon‐to‐nitrogen ratio and wave energy. 5. Our results indicate that the factors governing assemblage structure are scale dependent; niche‐based mechanisms act across all spatial scales, whereas community similarity declines with distance only at larger spatial separations.     

三种药液湿敷治疗多巴胺所致静脉炎的临床疗效比较

目的：通过三种药液外敷治疗经外周静脉输入或泵入多巴胺所引起的静脉炎的效果比较,总结出效果最佳的药液。方法：选择因长期静脉应用多巴胺,使用外周静脉留置针,并发静脉炎Ⅰ度或Ⅱ度的患者120例,随机分为三组,分别用50%硫酸镁注射液、10%硝酸甘油溶液、10%酚妥拉明溶液湿敷,每组40例,在湿敷后的1天,3天,7天观察静脉炎消退情况。结果：三种药液湿敷后的第3天在治疗效果方面有显著差异,且10%硝酸甘油溶液的治疗效果比较好,优于其它两种药物（P〈0.017）。结论：10%硝酸甘油溶液湿敷对多巴胺所致静脉炎的治疗效果明显,值得临床推广。     

微波高温灭活及自体髂骨异体骨粒复合骨水泥修复 治疗长骨骨巨细胞瘤骨缺损

目的:探讨微波高温灭活及自体髂骨、异体骨粒复合骨水泥修复骨巨细胞瘤病灶刮除后骨缺损的临床应用效果。方法:应用原位分离插入式微波天线高温灭活技术,自体髂骨、异体骨粒复合骨水泥修复21例长骨骨巨细胞瘤术后骨缺损,从手术技术、肿瘤复发情况、肢体关节功能等方面全面综合评价此方法临床应用效果。结果:21例患者均获得骨性愈合,无骨折及内固定断裂发生,2例复发,复发率9.8%;肢体关节功能优18例(85.7%)、良3例(14.3%)、中差0例。结论:微波高温能彻底杀灭肿瘤组织降低复发率,自体髂骨保证与近关节软骨下骨愈合,异体骨粒复合骨水泥能良好充填残余瘤腔、且具有良好的生物力学性能,以防发生关节软骨面塌陷。