左右半结肠癌多组学分子特征差异的研究进展

结肠癌(colon cancer,CC)是一种常见的恶性肿瘤,其发病率和死亡率均占癌症前列.根据解剖学位置,CC可分为左半结肠癌(left-sided colon cancer,LCC)和右半结肠癌(right-sided colon cancer,RCC),两者在临床特征上表现出较大的差异.近些年来,随着生物学技术和...     

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.     

短嘴金丝燕回声定位叫声特征

2012年6月,对湖南省石门县壶瓶山国家级自然保护区神景洞短嘴金丝燕的回声定位叫声进行研究,在黑暗山洞内使用录音仪器录制其自由飞行状态的声音后使用声音软件进行分析.短嘴金丝燕捕食归巢时,快速飞入洞口,在洞内有光区域不发声,到达洞内黑暗区域后开始发出回声定位叫声,且飞行速度减慢.声音分析结果表明其回声定位叫声为双脉冲组的噪声脉冲串型(noise burst),组内脉冲间隔很短[(6.6±0.42)ms],组间脉冲间隔较长[(99.3±3.86) ms],两者差异显著(P＜0.01).对比第一、第二脉冲声音参数发现,主频和脉冲时程差异不显著,第一、第二脉冲主频分别为(6.2±0.08) kHz和(6.2±0.10) kHz (P＞0.05);脉冲时程分别为(2.9±0.12) ms和(3.2±0.17) ms (P＞0.05);最高和最低频率差异显著,第一、第二脉冲最高频率分别为(20.1±1.10) kHz和(15.4±0.98) kHz (P＜0.01),最低频率分别为(3.7±0.12) kHz和(4.0±0.09)kHz (P＜0.05);第一脉冲频宽((16.5±1.17) kHz)宽于第二脉冲((11.4±1.01) kHz) (P＜0.01);且第一脉冲能量[(-32.5±0.60) dB]高于第二脉冲[(-35.2±0.94) dB] (P＜0.05).另外,短嘴金丝燕在黑暗山洞内的回声定位叫声还包含了部分超声波,最高频率可达33.2 kHz.     

稻瘟病菌群体的分子遗传学研究II.广东省2000年度稻瘟病菌群体遗传结构的时空特性

利用随机扩增多态性DNA技术对广东省2000年度稻瘟病菌群体的遗传结构进行了分析。以相似性系数为0.62阀值时,可将采集于广东省三大生态稻作区、早稻和晚稻生长季节的104个菌株划分为14个遗传宗谱;其中宗谱5和宗谱8的菌株数各占总数的25%,为优势宗谱;宗谱4和12的菌株数各占总数的14.4%和9.6%,为亚优势宗谱;其余的29个菌株,分别归属于其它10个宗谱,其中有5个宗谱是单菌株宗谱。本年度稻瘟病菌群体的遗传结构呈现明显的区域性特性:遗传结构呈由北向南多样化的趋势;各个稻作区甚或亚区有其特异性的宗谱。本年度稻瘟病菌群体的遗传结构也显示分明的生长季节特性:来源于早稻和晚稻生长季节的菌株完全分属于宗谱图的上下两个半区,彼此之间不存在共同的宗谱;而且后者的遗传宗谱要比前者的复杂、多样。研究还表明,虽然稻瘟病菌群体的遗传结构2000年度与1998-1999年度的比较存在较大的差异,但是两者仍然具有良好的相承性和可比性。如何进一步验证和把握稻瘟病菌群体的遗传结构所表现出的时空特性是值得我们进一步探讨的重要课题。     

微生物1,3-1,4-β-葡聚糖酶蛋白质改造及工业应用研究进展

1,3-1,4-β-葡聚糖酶(E.C.3.2.1.73)是一种重要的工业用酶,其可以通过特异性切割毗邻β-1,3-糖苷键的β-1,4-糖苷键将β-葡聚糖或地衣多糖降解为纤维三糖和纤维四糖。微生物β-葡聚糖酶属于糖苷水解酶家族16,其三维结构为卷心蛋糕状的逆向β-片层结构。文中综述了近些年来β-葡聚糖酶在工业上的应用情况及酶蛋白质工程改造的研究进展,并对其研究前景进行了展望。     

Lysophosphatidic Acid Acyltransferase from Coconut Endosperm Mediates the Insertion of Laurate at the sn-2 Position of Triacylglycerols in Lauric Rapeseed Oil and Can Increase Total Laurate Levels

Expression of a California bay laurel (Umbellularia californica) 12:0-acyl-carrier protein thioesterase, bay thioesterase (BTE), in developing seeds of oilseed rape (Brassica napus) led to the production of oils containing up to 50% laurate. In these BTE oils, laurate is found almost exclusively at the sn-1 and sn-3 positions of the triacylglycerols (T.A. Voelker, T.R. Hayes, A.C. Cranmer, H.M. Davies [1996] Plant J 9: 229–241). Coexpression of a coconut (Cocos nucifera) 12:0-coenzyme A-preferring lysophosphatitic acid acyltransferase (D.S. Knutzon, K.D. Lardizabal, J.S. Nelsen, J.L. Bleibaum, H.M. Davies, J.G. Metz [1995] Plant Physiol 109: 999–1006) in BTE oilseed rape seeds facilitates efficient laurate deposition at the sn-2 position, resulting in the acccumulation of trilaurin. The introduction of the coconut protein into BTE oilseed rape lines with laurate above 50 mol % further increases total laurate levels.     

PACAP protects neuronal differentiated PC12 cells against the neurotoxicity induced by a mitochondrial complex I inhibitor, rotenone

In vivo and in vitro studies have suggested a neuroprotective role for Pituitary adenylate cyclase activating polypeptide (PACAP) against neuronal insults. Here, we showed that PACAP27 protects against neurotoxicity induced by rotenone, a mitochondrial complex I inhibitor that has been implicated in the pathogenesis of Parkinson's disease (PD). The neuroprotective effect of PACAP27 was dose-dependent and blocked by its specific receptor antagonist, PACAP6-27. The effects of PACAP27 on rotenone-induced cell death were mimicked by dibutyryl-cAMP (db-cAMP), forskolin and prevented by the PKA inhibitor H89, the ERK inhibitor PD98059 and the p38 inhibitor SB203580. PACAP27 administration blocked rotenone-induced increases in the level of caspase-3-like activity, whereas could not restore mitochondrial activity damaged by rotenone. Thus, our results demonstrate that PACAP27 has a neuroprotective role against rotenone-induced neurotoxicity in neuronal differentiated PC12 cells and the neuroprotective effects of PACAP are associated with activation of MAP kinase pathways by PKA and with inhibition of caspase-3 activity; the signaling mechanism appears to be mediated through mitochondrial-independent pathways.     

Effects of size,neighbors, and site condition on tree growth in a subtropical evergreen and deciduous broad‐leaved mixed forest,China

Successful growth of a tree is the result of combined effects of biotic and abiotic factors. It is important to understand how biotic and abiotic factors affect changes in forest structure and dynamics under environmental fluctuations. In this study, we explored the effects of initial size [diameter at breast height (DBH)], neighborhood competition, and site condition on tree growth, based on a 3‐year monitoring of tree growth rate in a permanent plot (120 × 80 m) of montane Fagus engleriana–Cyclobalanopsis multiervis mixed forest on Mt. Shennongjia, China. We measured DBH increments every 6 months from October 2011 to October 2014 by field‐made dendrometers and calculated the mean annual growth rate over the 3 years for each individual tree. We also measured and calculated twelve soil properties and five topographic variables for 384 grids of 5 × 5 m. We defined two distance‐dependent neighborhood competition indices with and without considerations of phylogenetic relatedness between trees and tested for significant differences in growth rates among functional groups. On average, trees in this mixed montane forest grew 0.07 cm year^?1 in DBH. Deciduous, canopy, and early‐successional species grew faster than evergreen, small‐statured, and late‐successional species, respectively. Growth rates increased with initial DBH, but were not significantly related to neighborhood competition and site condition for overall trees. Phylogenetic relatedness between trees did not influence the neighborhood competition. Different factors were found to influence tree growth rates of different functional groups: Initial DBH was the dominant factor for all tree groups; neighborhood competition within 5 m radius decreased growth rates of evergreen trees; and site condition tended to be more related to growth rates of fast‐growing trees (deciduous, canopy, pioneer, and early‐successional species) than the slow‐growing trees (evergreen, understory, and late‐successional species).     

濒危药用植物桃儿七的离体培养研究

以桃儿七种子诱导的无菌苗为材料,研究了外源激素对芽诱导、增殖和生根的影响,建立了桃儿七离体培养再生体系。结果表明：芽诱导阶段,采用3.0 mg·L^-1 6-BA+0.5 mg·L^-1 GA₃激素组合,出芽率最高可达85-71%,缩短出芽时间30~40 d,在添加3.0 mg·L^-1 6-BA+0.2 mg·L^-1 IAA的MS培养基上利于增殖,增殖速度快,增殖系数1.63。以WPM+1.5 mg·L^-1 IAA+0.5 mg·L^-1 NAA的培养基培养30 d 后,生根率可达60.1%。