植物对环境应力刺激的生物学效应

植物生长在自然环境中由于其“不动性”而不可避免地要受到各种环境应力的刺激,应力－生长关系一直是生物学家和物理学家所关心的课题,是生物力学的灵魂。很多研究已经表明外界应力作用对植物的生长发育有着重要的影响。本综述了国内外关于应力对植物组织所引起的生物学效应,首先论述了环境应力所引起的宏观生物学效应,随后重点论述了环境应力所引起的生物学效应在细胞和分子水平上的研究,其中包括单个细胞的加载、电磁场、微     

利用生物效应比评价利咽丹质量的方法研究

目的:测定利咽丹(Liyan Dan,LYD)及其药效组分(active components alignment,ACA)抗Ⅰ型单纯疱疹病毒(HSV-Ⅰ)的生物效应比,探讨使用药效组分标准生物效价表述中药质量的新鉴定方法。方法:用MTT染色法检测对HSV-Ⅰ所致细胞病变(cytopathogenoc effect,CPE)的抑制作用,用HPLC和UV法检测药效组分。用利咽丹及其药效组分对感染HSV-Ⅰ的细胞保护率(protective percent,PP)计算其生物效应比(biologlical effect ratio,BER)。BERS=PPS／PPACA(药物对细胞的保护率／药效组分对细胞的保护率;药物浓度2-x mg/mL)。结果:利咽丹有抑制HSV-Ⅰ所致CPE的活性,其生物效应比为1．16。结论:中药及其药效组分的生物效应比可以反映和揭示其品质的内涵,该指标可以客观地表述中药疗效的本质。本研究提出了中药品质研究的新思路和方法,引入了生物效应比和药效组分的新概念。中药药效组分生物效应质量鉴定方法如下:第一,建立药效组分标准生物效应作为效应标准;第二,按照药效组分生物效应标准的检测方法测定供试品;第三,按照公式计算生物效应比(BERS=PPS／PPACA)。中药药效组分质量评价生物效应比标准:1≥BERS≥0．9时,为合格药品;BERS>1时为优质药品;BERS<0．9时为不合格药品。此质量评价方法比仅依靠一种或两种化学成分含量来评价质量要更科学。     

T细胞表位的确定

确定抗原分子被T细胞所识别抗原分子上的短肽序列,对T细胞表位进行定位对于特异性免疫应答的调节有重要意义。由于CD4~+T细胞表位和CD8~+T细胞表位在各方面性质的诸多不同,对这两种表位进行定位所采取的策略也应该是不同的。运用所选择的效应细胞对合成肽库的筛选是对CD4~+T细胞表位进行定位的有效策略,而对于CD8~+T细胞表位定位,需要通过一些特殊的手法将抗原肽导入细胞后进一步运用效应细胞进行筛选。     

阿片肽对骨髓未成熟B细胞的免疫学效应

 已经证明一些细胞象脾淋巴细胞、血T细胞、自然杀伤细胞和血小板存在有阿片受体。本文在骨髓细胞上的研究提示未成熟B细胞表面也存在有这类神经肽的受体,通过阿片肤类结合到细胞上可以观察到不同的效应。试验结果显示M-脑啡肽、L-脑啡肽和α-内啡肽对骨髓未成熟B细胞抗体生成反应的抑制分别为76.6％、68.6％和67.7％。相反,β-内啡肽增进抗体反应达78.0％。M-脑啡肽和两种内啡肽在未成熟B细胞上的效应能够被拮抗剂纳络酮所逆转,提示反应涉及阿片肽受体机制。     

血小板衍生生长因子对细胞的生物学效应

PDGF是血小板主要成分,是强有力的促细胞分裂剂,刺激多种类型细胞的分裂和增殖,具有广泛的细胞生物学效应。本文讨论了PDGF的作用机制,认为与酪氨酸激酶有关;简述了PDGF的细胞效应;对影响细胞周期的因素进行了探讨,并提出了今后对PDGF研究的可能方向。     

菠菜种子胰蛋白酶抑制剂对K-562细胞增殖的抑制及促凋亡作用研究

应用MTT法分析了菠菜种子胰蛋白酶抑制剂SOTI对人慢性髓原性白血病K-562细胞生长的影响。结果显示SOTI能够抑制K-562细胞的增殖,其抑制细胞增殖的作用呈现明显的剂量-效应关系;进一步观察了不同浓度的SOTI处理K-562细胞所导致的形态学变化和诱导凋亡作用,证实SOTI具有明显的体外抗癌活性,SO—TI的抗癌活性与其诱导凋亡有关。     

石油化学工人的细胞遗传学研究——Ⅱ.姐妹染色单体交换(SCE)和细胞生长周期的研究

本文研究了180名某大型石油化工企业工人和180名对照组的SCE频率及其细胞Ⅰ、Ⅱ、Ⅲ周期的比率,结果表明,石化工人的SCE频率和细胞各周期比率与对照组无显著差异,即这两个地区由环境因子引起的这种细胞遗传效应差异不显著,表明它们有较相似的环境背景。但是,在石化企业中,两个污水处理车间工人的SCE频率明显地高于对照组和4个生产车间的工人,其细胞生长速率也明显地迟缓,揭示石化物质对人体有一定的细胞遗传效应,而且这种效应与人体所接触的石化物质浓度有关。     

癌症研究的新前沿——肿瘤形成的遗传抑制(续)

与正常细胞的胞间相互作用所产生的转化细胞生长的抑制效应正常细胞可以产生抑制转化细胞生长的物质。20多年前,Staker 报道多瘤病毒转化的 BHK 细胞(一株叙利亚仓鼠肾细胞)的生长受到正常小鼠纤维母细胞的抑制。汇合生长的单层正常细胞抑制了与其接触的多瘤病毒转化的 BHK 细胞的生长。一旦细胞单层形成,X 光照射也不能减弱这一抑制效应。Stoker 认为该效应是由正常细胞内的生长抑制分子所介导的,     

离心法增加HaCaT细胞的基因转染效率

HaCaT细胞是自发性的人永生化表皮细胞株,常用于皮肤功能与疾病的相关研究,但常规脂质体法转染该细胞的效率极低。该研究主要探讨离心是否能够增加脂质体法转染HaCaT细胞的效率。以Lipofectamine~?2000为脂质体转染试剂,pEGFP-C1为质粒转染HaCaT细胞后分别使用常规法和离心法处理,利用荧光倒置显微镜和流式细胞仪测定转染效率;细胞增殖活力实验检测离心是否对细胞活力产生影响;荧光素酶报告基因、Western blot实验检测离心法实际效应对目的基因表达的影响。结果表明,离心法处理组所测得的转染效率均高于常规法处理组,差异有统计学意义。荧光素酶报告基因实验、Western blot实验则进一步证实了转染后离心的性价效应能增加目的基因的表达,具有较高的实用性。综上所述,常规转染步骤后离心能够增加HaCaT细胞的基因转染效率。     

PEG10基因转染的树突状细胞疫苗对肝癌细胞的杀伤实验研究

目的:研究印记基因PEG10修饰的树突状细胞(DC)疫苗对肝癌细胞的杀伤效应,为肝癌的治疗提供新的策略。方法:将重组PEG10腺病毒rAd-PEG10感染HLA-A2阳性的人外周血来源的DC,制备PEG10基因修饰的DC疫苗,并在体外刺激HLA-A2阳性限制性的单个核细胞,酶联免疫斑点试验(Enzyme Linked Immunospot Assay, ELISPOT)和标准⁵¹Cr释放试验分别检测PEG10腺病毒感染的DC所诱导的特异性CTL活性,并检测对HLA-A2阳性的HepG2肝癌细胞的杀伤作用。结果:成功制备了PEG10基因修饰的树突状细胞(DC)疫苗,并在体外能有效诱导抗原特异性CTL效应,对HepG2肝癌细胞有明显的杀伤毒性。结论:PEG10基因修饰的树突状细胞能有效激发出特异性CTL应答,并对HepG2肝癌细胞有明显的杀伤毒性,为肝癌治疗提供了新思路。     

Time-slot modulated electromagnetic fields of wireless communication systems: is there a health risk for man?

The safety guidelines of ICNIRP on bio-effects of low energy fields are based absorption and transformation into thermal effects. These guidelines are much higher than for acute reactions and long time exposure. It is pointed out that the guidelines for cordless telephone and mobile phone should correspond to long time exposure to low energetic electromagnetic fields.     

Sowing density and harvest time affect fibre content in hemp (Cannabis sativa) through their effects on stem weight

Sowing density and harvest time are considered important crop management factors influencing fibre quantity and quality in hemp (Cannabis sativa). We investigated whether the effects of these factors are essentially different or that both factors affect stem weight and thereby total and long‐fibre content. The effects of all combinations of three sowing densities and three harvest times were studied for six different stem parts. Almost 500 samples consisting of stem parts from 50 plants and with a length of 50 cm were tested. Fibres were extracted by a controlled warm‐water retting procedure, followed by breaking and scutching. The initial sample weight was fractionated into retting losses, wood, tow and long fibre. In both Italy and the Netherlands, crops were successfully established with different stem densities (99–283 m^?2), plant heights (146–211 cm) and stem diameters (4.5–8.4 mm) at harvest. Stem dry matter yields (6.8–11.7 Mg ha^?1) increased with a delay in harvest time but were not affected by sowing density. Retting loss percentages were lower in lower stem parts and decreased with later harvest because maturation was associated with increasing amounts of fibre and wood. Within a certain stem part, however, the absolute retting losses were constant with harvest time. Multiple linear regression analyses showed that the amount of fibre in a hemp stem is almost completely determined by the weight and the position of that stem part. When the plant grows, the increase in dry matter is split up into fibres and wood in a fixed way. This total fibre/wood ratio was highest in the middle part of the stem and lower towards both bottom and top. Sowing density and harvest time effects were indirect through stem weight. The long‐fibre weight per stem increased with the total fibre weight and hence with stem weight. Stem weight increased with harvest time; as harvest time did not affect plant density, the highest long‐fibre yields were obtained at the last harvest time. The long fibre/total fibre ratio was lowest in the bottom 5 cm of the stems but similar for all other parts. Sowing density and harvest time effects again were indirect. Fibre percentages in retted hemp decreased with increasing stem weights towards a level that is presumably a variety characteristic. The dry matter increase between harvests, however, is much more important with respect to total and long‐fibre yield.     

拐枣的食用价值研究——Ⅱ.食用安全性分析

本实验对食用拐枣的安全性进行了综合性研究。结果指出,拐枣无急性毒性。花期食用对实验动物的造血系统功能、肝肾功能、血脂代谢、血糖浓度、脏器重量及组织细胞的形态结构均无明显影响,可长期安全食用。     

The effect of low birth weight on height,weight and behavioral outcomes in the medium-run

A number of studies have documented negative long term effects of low birth weight. Yet, not much is known about the dynamics of the process leading to adverse health and educational outcomes in the long run. While previous studies focusing mainly on LBW effects on physical growth and cognitive outcomes have found effects of the same size at both school age and young adulthood, others have found a diminishing negative effect over time. The purpose of this paper was to bring new evidence to this issue by analyzing the medium run effects of low birth weight on child behavioral outcomes as well as physical growth at ages 6 months, 3½, 7½ and 11 years using data from the Danish Longitudinal Survey of Children. Observing the same children at different points in time enabled us to chart the evolution of anthropometric and behavioral deficits among children born with low birth weight and helped understanding the nature and timing of interventions.     

Long-Term Effects of Biosolids on Revegetation of Disturbed Sagebrush Steppe in Northwestern Colorado

A study was conducted to evaluate the long‐term effects of biosolids amendment on restoration of disturbed sagebrush steppe habitat in northwestern Colorado. Twenty‐four years after biosolids amendment, soil fertility and plant community development were studied in replicated plots receiving various biosolids amendments on two different substrates. The two substrates used were a subsoil, determined to have low initial fertility, and a topsoil over retorted shale substrate, determined to have relatively high initial fertility. Results suggest that biosolids amendments have long‐lasting effects on soil fertility and plant community composition, but these effects vary between the two substrates that were utilized. Within the plots established on subsoil, the long‐term effect of biosolids was a reduction in plant species diversity and dominance by perennial grasses. On the topsoil substrate, there was a decrease in perennial grasses and an increase in shrub dominance with increasing biosolids. Results demonstrate the importance of considering initial soil conditions, seed mixture, and biosolids application rate when using biosolids for restoration of disturbed sagebrush steppe habitat. The long‐term effects of the biosolids treatments at this site demonstrate the need to consider restoration treatment effects over longer and more ecologically meaningful time frames.     

The effect of long time delays in predator-prey systems

Past studies have indicated that a time delay longer than the natural period of a system will generally cause instability; however here it is shown that including long maturational time delays in a general predator-prey model need not have this effect. In each of the three cases studied (a predator delay, a prey delay, and both), local stability can persevere despite the presence of arbitrarily long time delays. This perseverence depends upon an interaction between delayed and undelayed features of the model. Delayed processes always act to destabilize the model. For example, prey self-regulation, usually a source of stability, becomes destabilizing if subject to a long delay. However, the effect of such a delay is offset by undelayed regulatory processes, such as a stabilizing functional reponse. In addition, the adverse effects of delayed predator recruitment can be reduced by the nonreproductive component of the numerical reponse, a feature not usually involved in determining stability. Finally, it is shown that long time delays are not necessarily more disruptive than short delays; it cannot be assumed that lengthening a time delay progessively reduces stability.     

Evaluation of the Probiotic Potential of Saccharomyces cerevisiae Strain (C41) Isolated from Tibicos by In Vitro Studies

Probiotics and Antimicrobial Proteins - Artisanal fermented beverages have been associated with beneficial effects for a long time. In Mexico, there are a wide variety of artisanal fermented...     

Contrasting effects of rabbit exclusion on nutrient availability and primary production in grasslands at different time scales

Herbivores influence nutrient cycling and primary production in terrestrial plant communities. However, both empirical and theoretical studies have indicated that the mechanisms by which herbivores influence nutrient availability, and thus their net effects on primary production, might differ between time scales. For a grassland in southeast England, we show that the effects of rabbits on primary production change over time in a set of grazed plots paired with exclosures ranging from 0 to 14 years in age. Herbivore exclusion decreased net aboveground primary production (APP) in the short term, but increased APP in the long term. APP was closely correlated with N mineralization rates in both grazed and ungrazed treatments, and accumulation of litter within the grazing exclosures led to higher N mineralization rates in exclosures in the long run. Rabbit grazing did not influence litter quality. The low contrast in palatability between species and the presence of grazing-tolerant plants might prevent rabbits from favoring unpalatable plant species that decompose slowly, in contrast to results from other ecosystems. Our results indicate that it is essential to understand the effects on N cycling in order to predict the effect of rabbit grazing on APP. Rabbits might decrease N mineralization and APP in the long term by increasing losses of N from grasslands.     

龙珍胶囊药理试验中血清谷丙转氨酶、尿素氮、肌酐的检测

本实验研究旨在考查长期服用 DTC 对大白鼠肝肾功能的影响。结果表明用 DTC 饲养3至6个月大白鼠血中,其转氨酶活力,尿素氮、肌酐的水平没有明显变化.实验结果提示 DTC 是一种安全药物,长期服用对肝肾功能的影响极微.     

Effects of normebaric and hyperbaric hyperoxia on digestive motricity of the awake rabbit. I Antropyloric motricity]

The effects of normobaric and hyperbaric hyperoxia (short and long time) have been studied on the pyloric antrum motility of the rabbit. The results show the absence of effect of normobaric oxygen in short application (twenty to thirty minutes), but its inhibiting effect on the pyloric antrum motility in long time application. The hyperbaric hyperoxia slows down the frequency of the pyloric antrum contractions so much more the pression is higher. This effect is independant of the speed to which the pression is set up, and also of the moment of day where the experiment is done.