一种联合MALDI-TOF MS直接鉴定阳性血培养瓶方法改进及与Sepsityper Kit试剂盒法、SELTERS法和血清分离胶法的比较

目的评价直接使用基质辅助激光解析电离飞行时间质谱(MALDI-TOF MS)联合Sepsityper Kit试剂盒法(简称试剂盒法)、SELTERS法和血清分离胶法(简称分离胶法)鉴定阳性血培养瓶血中细菌的符合率,并对SELTERS方法进行改进,以缩短样本处理时间。方法对656例临床血培养阳性标本,应用试剂盒法、SELTERS方法或分离胶法处理后,直接使用质谱仪快速鉴定菌株,同时进行传统培养,比较分析二者之间的差异。结果656例血培养阳性标本共分离出626株单种菌感染和30株多种菌感染标本。MALDI-TOF MS联合试剂盒法、SELTERS法或分离胶法可在1 h内快速鉴定血培养阳性标本。在单种细菌感染中,MALDI-TOF MS联合试剂盒法直接鉴定革兰阳性菌的种、属符合率分别是66.8%(141/211)、21.3%(45/211),革兰阴性菌的种、属符合率分别是97.1%(367/378)、0.8%(3/378),真菌的种、属符合率分别是32.4%(12/37)、0.0%(0/37);MALDI-TOF MS联合SELTERS法直接鉴定革兰阳性菌的种、属符合率分别是66.8%(141/211)、21.3%(45/211),革兰阴性菌的种、属符合率分别是96.3%(364/378)、2.4%(9/378),真菌的种、属符合率分别是32.4%(12/37)、2.7%(1/37);MALDI-TOF MS联合分离胶法直接鉴定革兰阳性菌的种、属符合率分别是51.2%(108/211)、20.9%(44/211),革兰阴性菌的种、属符合率分别是93.4%(353/378)、1.6%(6/378),真菌的种、属符合率分别是13.5%(5/37)、2.7%(1/37);MALDI-TOF MS联合改良SELTERS法直接鉴定革兰阳性菌的种、属符合率分别是59.1%(13/22)、18.2%(4/22),革兰阴性菌的种、属符合率分别是88.5%(23/26)、3.8%(1/26),真菌的种、属符合率分别是0.0%(0/2)、50.0%(1/2)。而对于多种菌感染的血培养瓶,3种方法鉴定率均较低。结论MALDI-TOF MS联合试剂盒法、SELTERS法或分离胶直接鉴定阳性血标本中的病原菌,其结果可在1 h内获得,并与传统培养结果相比具有较高的符合率。但是这些方法检测更快速、操作更简便,同时改良SELTERS法样本处理时间缩短,成本降低,且符合率与前3种方法没有区别。这4种方法均能满足临床快速诊断和及时有效抗菌治疗的需求,临床可根据自身情况选择。     

扫帚菜-白菜轮作对白菜镉吸收的影响

通过盆栽和大田试验研究扫帚菜Kochia scoparia对土壤中镉(Cd)的富集效率,并利用盆栽试验将其与4个白菜品种进行轮作试验,验证扫帚菜对土壤Cd污染的修复效果。结果表明,扫帚菜各部位富集能力表现为叶>根>茎,富集系数分别为15.07、5.44和2.96;种植扫帚菜后土壤总Cd降低6.02%-13.60%;土壤脲酶和酸性磷酸酶活性也有所提高。盆栽轮作结果表明,扫帚菜-白菜轮作系统中白菜地上部Cd含量与未轮作的对照组相比平均降低17.21%,生物量有略微增加,地上部对Cd的转运系数无明显变化。结果显示,通过扫帚菜与白菜轮作不仅可以增加白菜产量,而且可以有效降低白菜可食部Cd含量,实现边生产边治理的绿色农业理念。     

模拟不同降雨时间格局下喀斯特垂直异质生境对桢楠幼苗光合和生长的影响

由于岩石裸露、地表破碎、坡度陡峻、洼地土壤堆积等因素的共同作用,喀斯特区域土壤具有明显的不连续性和高度异质性,土壤侵蚀往往较为严重。喀斯特地区高度异质性的生境为植物提供了不同的水分、肥料、空气和空间,对植物的生长和生理具有显著影响。在全球气候变化下,降雨时间格局的改变可能将进一步加剧喀斯特的生境异质性。桢楠是我国特有的国家二级保护树种,虽然它只零星分布在喀斯特地区,但由于它能在岩石间生长得很好,仍被认为是一种可能的适宜树种。以二年生桢楠（Phoebe zhennan S.Lee）幼苗为研究对象,研究总降水量相同条件下两种降雨时间格局（I_2d：2 d降雨间隔;I_19d：：19 d降雨间隔处理）和三种垂直异质小生境（S₀：无石全土,S_1/2：半石半土,S_3/4：多石少土）对其光合生理和生长的影响。结果显示：（1）在I_2d条件下,桢楠幼苗的光合速率在半石半土生境（S_1/2）下最大,且有较大的地径和株高;而在I_19d条件下,桢楠的光合和生长（株高和地径）均随着岩溶裂隙层的增厚逐渐减小。（2）在全土生境（S₀）下,降雨时间格局的改变并不影响桢楠的光合和株高,而在有岩溶裂隙层的生境下（S_1/2和S_3/4）,降雨时间间隔的延长会抑制桢楠的光合和株高及地径的生长,提高气孔密度,且这种抑制或促进作用会随着岩溶裂隙层的增厚而加剧。研究表明,在降雨间隔时间短,降雨均匀充足时,有少量的岩溶裂隙能够促进桢楠的生长和光合,但降雨间隔时间延长后,这种作用丧失。另一方面,在土壤相对较厚时,降雨时间间隔的改变对桢楠的光合和生长影响不显著,但岩溶裂隙层的增加,加剧了降雨时间间隔增大对桢楠光合的负面影响。     

Mechano-growth factor induces migration of rat mesenchymal stem cells by altering its mechanical properties and activating ERK pathway

Mechano-growth factor (MGF) generated by cells in response to mechanical stimulation has been identified as a mechano effector molecule, playing a key role in regulating mesenchymal stem cell (MSC) function, including proliferation and migration. However, the mechanism(s) underlying how MGF-induced MSC migration occurs is still unclear. In the present study, MGF motivated migration of rat MSCs (rMSCs) in a concentration-dependent manner and optimal concentration of MGF at 50 ng/mL (defined as MGF treatment in this paper) was demonstrated. Notably, enhancement of mechanical properties that is pertinent to cell migration, such as cell traction force and cell stiffness were found to respond to MGF treatment. Furthermore, MGF increased phosphorylation of extracellular signal-regulated kinase (ERK), ERK inhibitor (i.e., PD98059) suppressed ERK phosphorylation, and abolished MGF-induced rMSC migration were found, demonstrating that ERK is involved molecule for MGF-induced rMSC migration. These in vitro evidences of MGF-induced rMSC migration and its direct link to altering rMSC mechanics and activating the ERK pathway, uncover the underlying biomechanical and biological mechanisms of MGF-induced rMSC migration, which may help find MGF-based application of MSC in clinical therapeutics.     

Hippocampal theta-driving cells revealed by Granger causality

The two-dipole model of theta generation in hippocampal CA1 suggests that the inhibitory perisomatic theta dipole is generated by local GABAergic interneurons. Various CA1 interneurons fire preferentially at different theta phases, raising the question of how these theta-locked interneurons contribute to the generation of theta oscillations. We here recorded interneurons in the hippocampal CA1 area of freely behaving mice, and identified a unique subset of theta-locked interneurons by using the Granger causality approach. These cells fired in an extremely reliable theta-burst pattern at high firing rates (～90 Hz) during exploration and always locked to ascending phases of the theta waves. Among theta-locked interneurons we recorded, only these cells generated strong Granger causal influences on local field potential (LFP) signals within the theta band (4-12 Hz), and the influences were persistent across behavioral states. Our results suggest that this unique type of theta-locked interneurons serve as the local inhibitory theta dipole control cells in shaping hippocampal theta oscillations.     

温度对黄瓜钝绥螨发育历期的影响

恒温条件下测定了以茶黄螨(Polyphagotarsonemus latus)为食的黄瓜钝绥螨(Amblyseius cuc-umeris)发育历期与温度的关系。结果表明,黄瓜钝绥螨在18、20、23、25、28、30和31℃温度条件下整个世代的发育历期分别是13．02、9．61、5．96、5．26、4．65、4．78和5．80d,32℃条件下黄瓜钝绥螨卵不能孵化,该螨整个世代最低临界、最适和最高临界发育温度分别为12.77,23．87和33．50℃。     

Pathogenicity of a new China variety of Metarhizium anisopliae (M. Anisopliae var. Dcjhyium) to subterranean termite Odontotermes formosanus

The pathogenicity of a new China variety of Metarhizium anisopliae (M. anisopliae var. dcjhyium) against the subterranean termite Odontotermes formosanus and the effect of the fungal fermented solution on hemolymph intracellular calcium were studied in laboratory. Conidia from the M. anisopliae var. dcjhyium were highly virulent for O. formosanus causing approximately 100% mortality 3 days post-inoculation in the concentration of 3x10(8) conidia/ml. The conidial clumps with conidial chains distributed on the cadavers of termite. When the termite was treated with 3x10(5) conidia/ml for 2 days, two constitutive proteins (91 and 105kDa) disappeared and a new specific protein (40kDa) appeared in the hemolymph of survivors relative to the controls. Hemolymph cells treated by the fungal fermented solution had a significantly higher level of intracellular calcium than controls 30min after treatment (x1.7). When the termite O. formosanus was infected by the entomopathogenic fungus M. anisopliae var. dcjhyium, hyphae invaded the integument and body cavity of the termite; well-developed muscles and fat tissue in the thorax of termite were decomposed and absorbed by hyphae, and formed the net structure; Hyphae seriously destroyed hemolymph, various tissues, pipelines and produced large number of conidia in the body of termite.     

重庆喀斯特生境中桢楠种群结构与动态特征

桢楠是我国珍稀渐危树种,国家二级保护植物,野生多散生于海拔1500 m以下的亚热带常绿阔叶林中。而喀斯特生境岩石裸露、土壤浅薄贫瘠、岩溶干旱频发,理论上并不适合喜湿耐荫且喜酸性土壤的桢楠生长及幼苗更新。因此重庆市大足区和永川区喀斯特生境中的天然桢楠种群可能存在一定的更新困难。为明确这两个桢楠种群的生存现状及动态特征,采用野外调查法,从径级结构、静态生命表、存活曲线、结构动态及分布格局等方面分析桢楠种群结构及其数量动态规律,以期预测种群未来发展趋势,为喀斯特地区桢楠种群的保护、群落更新及植被恢复提供理论基础。结果表明：(1)大足区桢楠种群的年龄结构趋于稳定型,而永川区桢楠种群的年龄结构为增长型。两地区幼苗充足但死亡率高。(2)静态生命表及相关曲线分析显示,两个桢楠种群存活数量总体上随径级增大而减少;两个桢楠种群的生存期望值在不同径级间存在波动,大足区桢楠种群在第Ⅱ径级而永川区则是第Ⅳ径级期望值最高。(3)两个种群的存活曲线均为Deevey-Ⅲ型,即幼树死亡率较高,并且种群的增长速度较为缓慢。(4)大足区种群为随机分布,永川区种群为集群分布;种群各生长发育阶段均为集群分布,但聚集强度随着龄...     

组织器官脱细胞支架的制备及研究进展北大核心CSCD

脱细胞基质(decellularized extracellular matrix, dECM)旨在去除引起免疫排斥的细胞,保留原组织结构和成分。由于其具有与原组织器官相似的结构和成分,在组织工程和生物医学的应用上受到广泛关注,已成为一种很有前景的生物医学材料。通过适当的脱细胞方法,dECM很容易能够从组织器官中获得。文中总结了脱细胞的方法及最新研究进展,同时对脱细胞后支架灭菌、交联和保存的方式进行综述,概括了不同组织器官获得的脱细胞支架的最新应用及进展。最后对脱细胞支架目前面临的问题和挑战进行分析,并展望了未来的发展趋势。     

基于多源遥感数据的农业干旱监测模型构建及应用

干旱监测问题是干旱灾害模拟与预警及旱灾防灾减灾的关键。基于2001-2013年淮河流域40个气象站资料、28个土壤墒情站点和中分辨率成像光谱仪（MODIS）多源遥感数据,采用SEN趋势法和标准化降水蒸散指数（SPEI）等方法,综合了大气-植被-土壤相互作用等多元成因,构建了适用于淮河流域多源综合遥感干旱监测模型,探讨淮河流域干旱时空规律。研究表明：（1）基于多源数据构建综合干旱监测模型,利用土壤墒情和典型年份干旱监测对综合干旱监测模型适用性进行评价,通过了P < 0.01的显著性检验,构建的模型可综合反映出农业和气象干旱多源信息;（2）淮河流域干旱面积和干旱频率大都集中在4-5月和7-9月,9月份受旱面积最大。河南省是淮河流域受旱频率最高,其干旱面积占淮河流域多年平均干旱面积比重最大（38%）,其次是安徽（22%）,旱地受旱面积比重大于水田受旱面积比重;（3）淮河流域2、3和5月干旱有显著减弱趋势;而1、4和6月则有增强趋势。淮河流域小麦灌浆-成熟时期（4-6月）缺水对小麦粮食产量影响显著,综合淮河流域干旱趋势变化,需强化淮河流域4月份小麦的干旱监测与旱灾预警。