胸腺细胞和细胞器水平的线粒体膜电势研究

以地塞米松(DEX)诱导小鼠胸腺细胞凋亡;利用PI和AnneXin V/PI流式细胞术分别检测细胞晚期和早期凋亡;利用JC-1和DiOC_6(3)/PI在细胞水平检测凋亡中线粒体膜电势(△ψm)变化：抽提线粒体,利用JC-1直接染色技术检测现存线粒体△ψm情况。实验结果显示,DEX显著诱导胸腺细胞早期和晚期凋亡,凋亡细胞主要来自G_0/G_1期;细胞水平可见DEX介导与△ψm相关的J-aggregate和DiOC_6(3)可染性降低,同时介导线粒体数量显著降低,6h细胞膜完整性无显著变化：单纯线粒体检测结果显示,多数线粒体维持正常△ψm。提示,DEX介导胸腺细胞凋亡中线粒体数量降低,现存线粒体多保持着正常△ψm以维持凋亡过程细胞能量供给。     

1-甲基-4-苯基-吡啶盐致多巴胺能细胞系MES23.5的死亡机制

通过测定环境毒素1-甲基-4-苯基-吡啶盐(MPP )作用于多巴胺能细胞系MES23．5后细胞存活率的变化及细胞线粒体膜电位(△ψM)、活性氧(ROS)、羟自由基、超氧化物岐化酶(SOD)的变化,发现MPP^ 作用于多巴胺能细胞系MES23．5,可导致细胞存活率显著性减少,浓度达到200mol／L以上后,细胞存活率的下降呈时间与MPP^ 浓度依赖;以200μmol/L MPP^ 作用细胞6∽48h后,△ψM逐渐下降、ROS、羟自由基逐渐增加,48h后SOD开始显著性减少。结果表明早期线粒体能量代谢障碍和膜电位变化导致ROS(尤其是羟自由基)含量增加是MPP^ 导致多巴胺能细胞氧化应激的原因,而细胞内自由基的清除机制受损,则最终导致细胞变性死亡。     

线粒体呼吸链复合体Ⅱ＋Ⅲ的电子传递与质子转移的偶联

研究了鼠肝线粒体内膜体呼吸链复合体Ⅱ＋Ⅲ的Ｈ＾＋／２ｅ比与△ψ的相关性及其调节因素,证明：（１）用光谱法测得复合体Ⅱ＋Ⅲ的电子传递与质子转换初速度的Ｈ＾＋／２ｅ比值接近４,与铁氰化钾脉冲法测得的结果相同,Ｈ＾＋／２ｅ随着△μＨ＾＋升高而逐渐下降,荧光透析法测定不同Ｆｅ＾３＋还原速率建立的不同△ψ时,证明Ｈ＾＋回漏对△ψ和Ｈ＾＋泵出速度的依赖性,讨论了呼吸链复合体Ⅱ＋Ⅲ电子传递与质子转移之间的偶联以     

nHAP对大鼠肝线粒体的生物活性作用

为了探讨羟基磷灰石纳米粒子(nHAP)对大鼠肝线粒体生物活性的影响,将nHAP直接作用于线粒体,在不同浓度和时间下测定线粒体标志酶琥珀酸脱氢酶(SDH)比活性,并与对照组进行比较。结果显示,当nHAP中水含量在10%以下时,线粒体生物活性未发现改变;当nHAP浓度递增时,在等时间段内,对线粒体SDH比活性呈逐步抑制作用;在不等时间段内,nHAP对线粒体SDH比活性的抑制作用与对照组相比较差异有显著性(p<0.05)。因此,nHAP对线粒体SDH比活性的抑制有浓度和时间的依赖性。     

热带雨林和亚热带季雨林灌木光合作用对水分胁迫的反应

生长在热带植物温室的热带雨林植物Piper hispidum和亚热带季风常绿阔叶林植物九节(Psychotria rubra),在灌水、环境的CO_2浓度和26℃下,饱和光强的最大光合速率(PN)分别为6.3和9.8μmol·m~(-2)·s~(-1)。在低的叶片/空气水蒸汽压陡度(△w=10毫巴·巴~(-1))情况下,每降低叶片水势(ψ)1巴,P.hispidum的PN降低0.38μmol·m~(-2)·s~(-1);当ψ为-8巴时,PN随△w增高而降低,其关系PN=7.02-0.06△w(r~2=0.7);ψ为—13巴时,PN与△w关系的直线斜率变小(0.02)。对于九节,PN对△w变化的反应更为敏感。在ψ为-8.75巴时,PN=11.16—0.1△w(r~2=0.65)。在高ψ(-8和-8.75巴)情况下,两种灌木的气孔传导率(g)随△w的变化而相近;但ψ降低时,九节的g对△w的变化反应较P.hispidum敏感。ψ降低导致两种灌木的水分利用效率(WUE,μmol·m~(-2)·s~(-1)CO_2同化/mmol·m~(-2)·s~(-1)水散失)增高;而△w增高,WUE降低。九节的PN对△w增高的反应较P.hispidum敏感。     

银杏叶提取物对过氧化氢诱导的星形胶质细胞氧化损伤的保护作用

目的 研究银杏叶提取物（EGb761）对H2O2所致星形胶质细胞氧化损伤的保护作用。方法 用不同浓度的EGb761预处理细胞,再加入H2O2,通过噻唑蓝（MTT）实验、线粒体跨膜电位（△ψm）及细胞色素C释放实验、DNA损伤实验及半胱氨酰天冬氨酸特异性蛋白酶-3（Caspase-3）活性测定,观察EGb761对细胞存活率、线粒体膜通透性、DNA氧化损伤及Caspase-3活性的影响。结果 EGb761能明显降低Hz02对星形胶质细胞的氧化损伤,提高细胞的存活率;维持线粒体膜的完整性,抑制跨膜电位的耗散和细胞色素C的释放;抑制Caspase-3的活化和DNA的降解。结论 EGb761具有清除活性氧,减轻H2O2所致星形胶质细胞的氧化损伤,对星形胶质细胞有保护作用。     

球孢菌素A和Bcl—2高表达对EGTA诱导HL—60细胞凋亡的影响

研究线粒体PT孔专一抑制剂环孢菌素A（CsA）和Bcl-2高表达对EGTA诱导HL－60细胞凋亡的影响。流式细胞仪检测凋亡峰、染色质凝聚的PI和Hoechst33342荧光双染观察、DNA梯状条带分析均表明,CsA明显促进EGTA诱导的HL－60细胞凋亡,而Bcl-2高表达完全阻断细胞凋亡的发生,借助荧光探针rhodamine123和CMXRos研究细胞凋亡过程线粒体△ψm下降,而Bcl-2高表达使HL－60细胞的线粒体△ψm提高了近1倍,并完全抑制EGTA诱导的线粒体△ψm下降。     

常氧及低氧下孵育液中钙浓度改变对心肌线粒体钙含量及其呼吸功能损伤的影响

在常氧孵育中,当孵育介质自由钙离子浓度升高时,离体心肌线粒体钙含量显著增加。同时,线粒体状态4呼吸速率也明显加快并与其钙含量的增加呈正相关关系。在低氧孵育中,当孵育介质自由钙离子浓度升高时,离体心肌线粒体钙含量没有明显的增加,其状态4呼吸速率虽有加快但程度明显较常氧孵育时低。另外,在低孵育介质自由钙离子浓度(pCa8.0)的条件下,低氧可引起轻微的线粒体状态4呼吸速率加快。从以上结果作者推测,低氧引起心肌细胞的线粒体损伤可能主要不是低氧直接对线粒体作用所造成的,而是由低氧引起的心肌细胞胞浆环境变化对线粒体破坏的结果。其中胞浆自由钙离子的升高可能是一个的原因。     

啤酒废水二相厌氧消化动力学研究

本工作分阶段研究了啤酒废水厌氧消化反应特性。酸化初始速度很快,ｐＨ下降至４．０以下时,酸化产物对酸化菌代谢活性具有显著的抑制效应。系统ｐＨ值的大小对甲烷化过程中底物降解速率、产气速率和产气质量均有显著影响。ｐＨ６．５以上时,高浓度底物不构成底物抑制。底物浓度低于５００ｍｇ／Ｌ,甲烷化速率明显下降。合理控制预酸化程度以及甲烷化反应器的进料速率是提高厌氧消化处理效率,维持系统稳定性的关键措施。     

神经酰胺以Caspase依赖和非依赖方式诱导线粒体凋亡蛋白释放

本研究探讨了外源性C2-神经酰胺诱导入结肠癌HT-29细胞凋亡中,线粒体膜间隙凋亡蛋白的释放机制．不同浓度C2-神经酰胺作用HT-29细胞,流式细胞仪检测线粒体膜电位（△ψm）,线粒体／细胞液分离试剂盒分离亚细胞成分,聚丙烯酰胺凝胶电泳检测细胞色素C（Cytc）、高温必需蛋白A2（HtrA2）、线粒体源性半胱天冬氨酸蛋白酶第二活化因子（Smac）、凋亡抑制蛋白（XtAP）和半胱天冬氨酸蛋白酶-3（Caspase-3）蛋白表达水平．实验结果显示25和50μmol／L C2-神经酰胺作用细胞6h,△ψm即开始下降（P〈0．05）,且环孢霉素能通过调节线粒体膜通透性转换孔抑制△ψm的下降．C2-神经酰胺对Cyt c,HtrA2和Smac总蛋白表达没有明显影响,但能诱导Cyt c,HtrA2和Smac从线粒体释放入细胞液中,并下调XIAP蛋白的表达及活化Caspase-3．在Caspase抑制剂存在下,C2-神经酰胺仍能诱导Cyt c和HtrA2从线粒体释放,但不能诱导Smac释放．因此认为C2-神经酰胺能通过线粒体凋亡通路诱导HT-29细胞凋亡,C2-神经酰胺诱导Cytc和HtrA2从线粒体的释放是Caspase非依赖性的,而Smac释放是Caspase依赖性的．     

ENERGY AND VISION

A method was devised for measuring the minimum visibile in different parts of the spectrum, as done by Langley in 1888. The results are generally in good agreement with those given by this author, although not as close on both sides of the wave length 0.55 µ; this may be due partly to the use of a rock salt prism, to the fact that the minimum was determined by looking at a beam of diffused transmitted, instead of diffused reflected light, and also to the fact that Langley experimented with the sun, through the earth''s atmosphere, and had to take into account the thickness of the atmosphere interposed and the brightness of the sky. Although his experiments were made with great care, the differences from one day to another are important. However, when he expresses the energy in absolute units, he always refers to the same mean amount of energy radiated by the sun on 1 sq. cm. This amount is certainly not constant, if one judges from the differences observed in two measurements of sensitivity of the eye of the same individual at different dates. On the contrary, for a given wave length, our measurements always agreed closely, as our source of radiation was very nearly constant, owing to the absence of a varying amount of water vapor interposed. This may in some way account for the discrepancies observed.     

ENERGY,QUANTA, AND VISION

1. Direct measurements of the minimum energy required for threshold vision under optimal physiological conditions yield values between 2.1 and 5.7 x 10^–10 ergs at the cornea, which correspond to between 54 and 148 quanta of blue-green light. 2. These values are at the cornea. To yield physiologically significant data they must be corrected for corneal reflection, which is 4 per cent; for ocular media absorption, which is almost precisely 50 per cent; and for retinal transmission, which is at least 80 per cent. Retinal transmission is derived from previous direct measurements and from new comparisons between the percentage absorption spectrum of visual purple with the dim-vision luminosity function. With these three corrections, the range of 54 to 148 quanta at the cornea becomes as an upper limit 5 to 14 quanta actually absorbed by the retinal rods. 3. This small number of quanta, in comparison with the large number of rods (500) involved, precludes any significant two quantum absorptions per rod, and means that in order to produce a visual effect, one quantum must be absorbed by each of 5 to 14 rods in the retina. 4. Because this number of individual events is so small, it may be derived from an independent statistical study of the relation between the intensity of a light flash and the frequency with which it is seen. Such experiments give values of 5 to 8 for the number of critical events involved at the threshold of vision. Biological variation does not alter these numbers essentially, and the agreement between the values measured directly and those derived from statistical considerations is therefore significant. 5. The results clarify the nature of the fluctuations shown by an organism in response to a stimulus. The general assumption has been that the stimulus is constant and the organism variable. The present considerations show, however, that at the threshold it is the stimulus which is variable, and that the properties of its variation determine the fluctuations found between response and stimulus.     

螺旋藻变藻蓝蛋白内能量传递机制的研究

利用ｐｓ时间分辨荧光光谱技术研究两种不同结构变藻蓝蛋白复合物ＡＰ６６５和ＡＰ６６０内能量传递过程,讨论了变藻蓝蛋白三聚体和单体内激发态作用机制。结果表明,ＡＰＣ单体只有一个短寿命（７５ｐｓ）,来源于其两个亚基α８４／β８４间能量传递过程,另一长寿命（１０８０ｐｓ）是β８４基态恢复的平衡时间。两种ＡＰＣ三聚体均含有一个短寿命组分,从１６ｐｓ（ＡＰ６６０）到４８ｐｓ（ＡＰ６６５）,它们来源于三聚体内互为Ｃ３对称单体内α８４／β８４间能量传递过程。ＡＰ６６０由于结构对称性低出现的短寿命组分（１０６ｐｓ）,可指认为低对称单体的α８４／β８４之间能量传递时间常数。连接多肽对ＡＰＣ三聚体性质的影响明显地表现在其荧光衰减动力学过程中。     

喜马拉雅旱獭的能量代谢初试

喜马拉雅旱獭(Marmota himalayana)是青藏高原上的特有种,目前还未见有关生理学研究资料。我们于1982年12月1-10日,对5只喜马拉雅旱獭作了能量代谢的初步测定,现报道如下。 喜马拉雅旱獭捕自青海省海晏县热水滩地区,11月初送到我所饲养房喂养。12月份,饲养室气温为5-15℃,旱獭仍进食未冬眠。试验时,室温控制在10-13℃。用半导体点温计测肛温,由心电图计算心率。能量代谢试验通过改装的口鼻罩收集连续5分钟呼出气体,用煤气流量计测呼出气体量,用英国的Corning165型pH/Blood gas分析仪测定呼出气中CO₂与O₂含量,计算出O₂耗量与CO₂产生量,进而推算出呼吸商,产热量及基础代谢量。又用密闭式呼吸室法测得呼吸商与其口鼻罩法测得的结果讲行比较。     

SEAWEED ABUNDANCE AND DIVERSITY IN HIGH ENERGY AND LOW ENERGY AREAS AT PORT ARANSAS,TEXAS JETTIES

Agan, J. C. & Lehman, R. L. Department of Physical and Life Sciences, Texas A&M University-Corpus Christi 6300 Ocean Dr., Corpus Christi, TX 78412 USA Benthic algal sampling from high and low energy zones at a selected site on the south jetty at Port Aransas, Texas was completed between April 1999 and February 2000. Species composition and seasonal periodicity in relation to temperature and salinity fluctuations were determined. Dominant plants throughout the year included Bryocladia cuspidata, Bryocladia thyrsigera, Gelidium pusillum, Centroceras clavulatum, Ulva fasciata, and Padina gymnospora. The Rhodophyta dominated species coverage, along with biomass accumulation, although Chlorophyta species accrued the greatest biomass on the high energy side in April and June sampling. Chlorophyta are important to benthic coverage and biomass in the shallowest of waters, despite being fewer in species richness. Phaeophyta species including Petalonia fascia, Hincksia mitchelliae, and Ectocarpus siliculosus were found only during the cooler months. Padina gymnospora was the one exception as it was collected year-round. Results indicate that a greater Rhodophyta abundance was found on the channel side (low energy), where as, the surf side (high energy) contained a greater Chlorophyta abundance. Phaeophyta abundance for both high and low energy sites were comparable possibly due to the greater depth of water in which they are located. Little variance occurred in average biomass accumulation throughout the year. Highest biomass was in August (216.613g dry weight) with lowest occurring in April (107.4205g dry weight).