衡山青冈栎群落结构及物种多样性研究

利用样方法进行野外群落调查,共设计了15个样方,每个样方大小为20m×5 m,对衡山青冈栎(Cyclobalanopsis glauca)群落的种类组成、外貌、结构特征及物种多样性进行了研究.结果表明:在1 500 m2样地中,共有维管束植物26科37属46种,其中优势科为壳斗科、山茶科和蔷薇科等;该群落主要是以青冈栎为主的单优种群落,生活型谱以高位芽植物占绝对优势,叶级谱以中、小型叶为优势的特点,群落季相不明显;群落分层较明显,乔木层树种很少,灌木层种类较丰富,对群落物种多样性具有较大影响;物种多样性分析显示该群落多样性指数偏低,其多样性复杂程度由高到低的顺序为灌木层、藤本层、乔木层、草本层.     

Diazoxide Pretreatment Prevents Aβ1–42 Induced Oxidative Stress in Cholinergic Neurons Via Alleviating NOX2 Expression

The aggregation and accumulation of amyloid-β (Aβ) plays a significant role in the pathogenesis of Alzheimer’s disease. Aβ is known to increase free radical production in neuronal cells, leading to oxidative stress and cell death. Diazoxide (DZ), a highly selective drug capable of opening mitochondrial ATP-sensitive potassium channels, has neuroprotective effects against neuronal cell death. However, the mechanism through which DZ protects cholinergic neurons against Aβ-induced oxidative injury is still unclear. The present study was designed to investigate the effects of DZ pretreatment against Aβ_1–42 induced oxidative damage and cytotoxicity. Through measures of DZ effects on Aβ_1–42 induced cellular damage, reactive oxygen species (ROS) and MDA generation and expressions of gp91phox and p47phox in cholinergic neurons, new insights into the neuroprotective mechanisms can be derived. Aβ_1–42 significantly decreased 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide levels and increased ROS and MDA production; all effects were attenuated by pretreatment with DZ or diphenyleneiodonium chloride (a NOX2 inhibitor). Pretreatment with DZ also attenuated the upregulation of NOX2 subunits (gp91phox and p47phox) induced by Aβ_1–42. Since NOX2 is one of the main sources of free radicals, these results suggest that DZ can counteract Aβ_1–42 induced oxidative stress and associated cell death by reducing the level of ROS and MDA, in part, by alleviating NOX2 expression.     

Optimal stimulation frequency for vibrational optical coherence elastography

Vibrational optical coherence elastography (OCE) is a promising tool for extracting the mechanical property of soft tissue. Purpose of this study is focusing on settling the optimal frequency range for vibrational OCE with evenly distributed stress filed. A finite element model of 2% agar phantom was built by ANSYS with a vibration stimulation frequency range from 200 to 3000 Hz. Practical experiments were carried out for cross‐validation with the same frequencies and sample. Lateral and horizontal stress filed distributions under different frequencies were mathematically evaluated by coefficient of variance and degree of linearity. Results from simulation and practical experiment cross‐validated each other and 1000 Hz was set as the maximum ideal frequency for vibrational OCE, while the minimum frequency is set by theoretical calculation with a result of 250 Hz. An ex vivo biological sample was utilised to testify performance of vibrational OCE with excitation frequencies in and out of concluded optimal range, which showed that stiffness was better mapped out in optimal frequency range.     

耐钙心肌细胞的分离和电生理特性观察

用快速、恒压的无钙和胶原酶Ｔｙｒｏｄｅ液相继灌流豚鼠心脏冠脉系统后,再经无钙液室温浸泡心脏和用改变的Ｋ－Ｂ液帮助分离细胞的恢复,可获得耐钙的游离心肌细胞。全细胞电流记录：静息电位为－７２±９ｍＶ（ｎ＝１２）,并显示出快内向电流（ＩＮａ）,可被异搏定阻断的慢钙离子流和时间依赖性外向钾流（Ｉｋ）;单通道记录分别显示了Ｎａ＋Ｃａ２＋和Ｋ＋通道的电压依赖性等特征。结果表明了用此法分离的细胞具有耐钙性和正常电生理特性。     

Wangella harbinensis gen. nov., sp. nov., a new member of the family Micromonosporaceae

A novel endophytic actinomycete, designated strain NEAU-J3^T, was isolated from soybean root (Glycine max (L.) Merr) and characterized using a polyphasic approach. Phylogenetic analysis based on 16S rRNA gene sequences suggested that strain NEAU-J3^T fell within the family Micromonosporaceae. The strain was observed to form an extensively branched substrate mycelium, which carried non-motile oval spores with a smooth surface. The cell walls of strain NEAU-J3^T were determined to contain meso-diaminopimelic acid and galactose, ribose and glucose were detected as whole-cell sugars. The major menaquinones were determined to be MK-9(H₄) and MK-9(H₆). The phospholipids detected were phosphatidylcholine and phosphatidylethanolamine. The major cellular fatty acids were determined to be C_16:0, C_18:1 ω9c, C_18:0, C_17:0, C_17:1 ω7c, anteiso-C_17:0, C_16:1 ω7c and C_15:0. The DNA G + C content was 62.5 mol%. On the basis of the morphological and chemotaxonomic characteristics, phylogenetic analysis and characteristic patterns of 16S rRNA gene signature nucleotides, strain NEAU-J3^T is considered to represent a novel species of a new genus within the family Micromonosporaceae, for which the name Wangella harbinensis gen. nov., sp. nov. is proposed. The type strain of Wangella harbinensis is strain NEAU-J3^T (=CGMCC 4.7039^T = DSM 45747^T).     

EST-SSR markers from Heterodera glycines Ichinohe

The soybean cyst nematode Heterodera glycines Ichinohe is a severe agricultural pest for which genetic resources are limited. In this study, 295 simple sequence repeats (SSRs) were identified from 259 expressed sequenced tags (ESTs), which were selected from 9,443 unigenes. The successful primer pairs were designed against six regions. In total, 30 alleles were identified from 30 individuals using the six markers, with an average of five alleles per locus (range, 4–7). The observed and expected heterozygosities were 0.074–0.900 and 0.266–0.775, respectively. Significant departure from Hardy-Weinberg equilibrium was found at three of the six loci. The EST-based SSR markers developed in this study may contribute to better under-standing of the genetic structure of H. glycines populations.     

辛伐他汀对动脉粥样硬化大鼠凋亡相关基因Fas及FasL蛋白表达的影响

目的通过研究辛伐他汀对动脉粥样硬化大鼠血管壁中细胞凋亡相关基因Fas及FasL蛋白表达产物的影响,探讨其在预防动脉粥样硬化发生中的可能机制。方法复制动脉粥样硬化大鼠模型,以辛伐他汀干预,取胸主动脉,观察其斑块变化,采用免疫组化Elivision法测定动脉粥样硬化血管壁中Fas、FasL蛋白表达。结果Fas蛋白表达在实验组明显高于对照组及干预组(P<0.01,P<0.05),实验组FasL蛋白表达也明显高于对照组及干预组(P<0.05)。结论Fas及FasL基因通过促进细胞凋亡作用而诱发动脉粥样硬化过程,辛伐他汀可通过调节细胞凋亡过程发挥抗动脉粥样硬化作用。     

Immune-related microRNAs are abundant in breast milk exosomes

Breast milk is a complex liquid rich in immunological components that affect the development of the infant's immune system. Exosomes are membranous vesicles of endocytic origin that are found in various body fluids and that can mediate intercellular communication. MicroRNAs (miRNAs), a well-defined group of non-coding small RNAs, are packaged inside exosomes in human breast milk. Here, we identified 602 unique miRNAs originating from 452 miRNA precursors (pre-miRNAs) in human breast milk exosomes using deep sequencing technology. We found that, out of 87 well-characterized immune-related pre-miRNAs, 59 (67.82%) are presented and enriched in breast milk exosomes (P < 10(-16), χ(2) test). In addition, compared with exogenous synthetic miRNAs, these endogenous immune-related miRNAs are more resistant to relatively harsh conditions. It is, therefore, tempting to speculate that these exosomal miRNAs are transferred from the mother's milk to the infant via the digestive tract, and that they play a critical role in the development of the infant immune system.