淹水胁迫下江南牡丹生长及光合特性研究

以3年生江南牡丹品种‘凤丹白’为材料,利用盆栽淹水法,设置正常管理、轻度胁迫和重度胁迫3个水平,研究不同淹水胁迫水平对牡丹生长和光合特性的影响。结果表明：经过30 d胁迫后,正常管理、轻度胁迫和重度胁迫下的江南牡丹苗高生长量分别为3.6、1.1和0.73 cm,地径生长量分别为0.21、0.11和0.06 cm,植株总生物量增加量分别为7.0、3.0和2.75 g,淹水胁迫和正常生长差异显著,淹水胁迫严重影响了江南牡丹的生长。同时,在正常管理时,牡丹总叶绿素含量升高,而在淹水胁迫下呈下降趋势。淹水胁迫不同时间根系活力均呈下降趋势且随着胁迫程度的增加下降越大。正常管理下光合速率逐渐增加而胁迫条件下光合速率逐渐降低。同时胁迫条件下,牡丹蒸腾速率、气孔导度均明显下降;轻度淹水胁迫下胞间CO2浓度先升高后降低;而重度胁迫下胞间CO2浓度呈现逐渐升高的变化趋势。淹水胁迫对牡丹根系活力、茎段生长和叶片光合特性影响较大。该研究结果为江南牡丹耐涝胁迫机理研究奠定了理论基础。     

2018年感染病领域十大进展

2018年已缤纷落幕,2019年带着对未来的期许纷至沓来。回顾过去,展望未来,本文整理了2018年世界乃至中国感染病界的几项重大事件与进展,并进一步梳理了该领域的发展趋势。     

子痫前期患者血清APN、TNF-α、Apelin水平的表达及相关性研究

目的:探讨子痫前期患者血清脂联素(APN)、肿瘤坏死因子-α(TNF-α)、Apelin水平的表达及相关性。方法:选取2015年10月到2017年8月在辽河油田总医院妇产科就诊的子痫前期患者86例,根据患者的病情严重程度将其分为轻度子痫前期组(46例)和重度子痫前期组(40例),另选取同期在我院进行产检的健康孕妇40例作为对照组,比较三组受试者血清中APN、TNF-α、Apelin、低密度脂蛋白胆固醇(LDL-C)、甘油三酯(TG)、高密度脂蛋白胆固醇(HDL-C)和总胆固醇(TC)水平,并分析子痫前期患者血清中APN、TNF-α、Apelin、LDL-C、TG、HDL-C、TC的相关性。结果:重度子痫前期组血清中APN水平低于轻度子痫前期组和对照组,TNF-α、Apelin水平高于轻度子痫前期组和对照组(P0.05);轻度子痫前期组血清中APN水平低于对照组,TNF-α、Apelin水平高于对照组(P0.05)。重度子痫前期组血清中LDL-C、TG、TC水平高于轻度子痫前期组和对照组,HDL-C水平低于轻度子痫前期组和对照组(P0.05);轻度子痫前期组LDL-C、TC水平高于对照组,HDL-C水平低于对照组(P0.05)。Pearson相关性分析结果显示,子痫前期患者血清中APN与TNF-α、Apelin、LDL-C、TG呈负相关,与HDL-C呈正相关(P0.05);TNF-α与Apelin、LDL-C、TG、TC呈正相关,与HDL-C呈负相关(P0.05);Apelin与LDL-C、TG、TC呈正相关,与HDL-C呈负相关(P0.05)。结论:子痫前期患者血清中APN水平明显下降,TNF-α、Apelin明显升高,三种指标可相互影响,且均可影响机体的脂质代谢水平,共同调节子痫前期患者的疾病进展。     

七姊妹山常绿落叶阔叶混交林物种多样性格局及其环境解释

依托七姊妹山自然保护区6 hm²森林动态监测样地研究平台,基于样地和物种基本信息数据,采用多元回归树和冗余分析研究方法,探讨地形因子对生境的塑造作用及物种分布特征,分析不同群丛类型下物种多样性的变化规律。结果表明：(1)依据“1 SE”规则,4次分割依次以海拔(1 453 m)、坡度(23.13°)、海拔(1 398 m)、凹凸度(4.094)为分界点可将150个样地分为5个群丛。(2)冗余分析表明地形因子对物种分布解释量为0.077 6,解释率为16.36%,各环境因子对物种分布的解释力度依次为：海拔>坡度>凹凸度;坡向与物种的分布无显著相关性。(3)5个群丛中立木密度与胸高截面积最高的均为群丛5(527.4株/400 m²;3.495 cm²/株),立木密度与平均胸高截面积最低为群丛4(225.4株/400 m²;3.057 cm²/株)。(4)5个群丛中Shannon Winener丰富度指数与Simpson优势度指数最高的均为群丛2,最低的为群丛5,物种多样性尺度效应明显;Pielou均匀度指数最高为群丛4,最低为群丛5。(5)两两群丛间Jaccard相似性系数最低为群丛1 群丛2(0.331),最高的为群丛4 群丛5(0.645),海拔对β多样性格局影响较大。研究认为,七姊妹山自然保护区6 hm²样地地形因子对该区域生境的塑造具有一定作用,海拔、坡度、凹凸度组成的“环境筛”影响了该区域的物种分布及多样性格局。     

嗜热链球菌胞外多糖EPS333对酸乳品质的影响

本研究以酸乳为基质,通过测试酸乳酸化速率曲线、脱水收缩敏感性、持水力、水分迁移、质构及流变特性等参数,研究了嗜热链球菌胞外多糖与市场常规应用多糖对酸乳品质的影响。研究结果表明:嗜热链球菌胞外多糖EPS333在酸乳凝胶过程中较其他几种多糖能明显减缓酸化趋势,后熟及储藏阶段减少"自由水"含量,降低流动性,改善其流变特性。     

Shaping and stretching life by autophagy

In a recent study published in Science, demonstrate that genes required for autophagy act downstream of insulin-like signaling, and are involved in the expression of major life history traits, including dauer larva development and adult life span.     

Attachment of Listeria monocytogenes to radish tissue is dependent upon temperature and flagellar motility

Outbreaks of listeriosis and febrile gastroenteritis have been linked to produce contamination by Listeria monocytogenes. In order to begin to understand the physiology of the organism in a produce habitat, the ability of L. monocytogenes to attach to freshly cut radish tissue was examined. All strains tested had the capacity to attach sufficiently well such that they could not be removed during washing of the radish slices. A screen was developed to identify Tn917-LTV3 mutants that were defective in attachment to radish tissue, and three were characterized. Two of the three mutations were in genes with unknown functions. Both of the unknown genes mapped to a region predicted to contain genes necessary for flagellar export; however, only one of the two insertions caused a motility defect. The third insertion was found to be in an operon encoding a phosphoenolpyruvate-sugar phosphotransferase system. All three mutants were defective in attachment when tested at 30 degrees C; the motility mutant had the most severe phenotype. However, not all of the mutants were defective when tested at other temperatures. These results indicate that L. monocytogenes may use different attachment factors at different temperatures and that temperature should be considered an important variable in studies of the molecular mechanisms of Listeria fitness in complex environments.     

Conserved and divergent functions of Drosophila atonal,amphibian, and mammalian Ath5 genes

Insect and vertebrate eyes differ in their formation, cellular composition, neural connectivity, and visual function. Despite this diversity, Drosophila atona and its vertebrate Ortholog in the eye, Ath5, each regulate determination of the first retinal neuron class-R8 photo-receptors and retinal ganglion cells (RGCs)-in their respective organisms. We have performed a cross-species functional comparison of these genes. In ato mutant Drosophila, ectopic Xenopus Ath5 (Xath5) rescues photoreceptor cell development comparably with atonaI. In contrast, mouse Ath5 (Math5) induces formation of very few ommatidia, and most of these lack R8 cells. In the developing frog eye, ectopic atonal, like Xath5, promotes the differentiation RGCs. Despite strong conservation of atonaI, Xath5, and Math5 structure and shared function, other factors must contribute to the species specificity of retinal neuron determination. These observations suggest that the atonaI family may occupy a position in a gene hierarchy where differences in gene regulation or function can be correlated with evolutionary diversity of eye development.     

Inactivation of Numb and Numblike in embryonic dorsal forebrain impairs neurogenesis and disrupts cortical morphogenesis

Numb and Numblike, conserved homologs of Drosophila Numb, have been implicated in cortical neurogenesis; however, analysis of their involvement in later stages of cortical development has been hampered by early lethality of double mutants in previous studies. Using Emx1(IREScre) to induce more restricted inactivation of Numb in the dorsal forebrain of numblike null mice beginning at E9.5, we have generated viable double mutants that displayed striking brain defects. It was thus possible to examine neurogenesis during the later peak phase (E12.5-E16.5). Loss of Numb and Numblike in dorsal forebrain resulted in neural progenitor hyperproliferation, delayed cell cycle exit, impaired neuronal differentiation, and concomitant defects in cortical morphogenesis. These findings reveal novel and essential function of Numb and Numblike during the peak period of cortical neurogenesis. Further, these double mutant mice provide an unprecedented viable animal model for severe brain malformations due to defects in neural progenitor cells.