生物光子辐射的研究进展

生物光子辐射来自生物分子从高能态向低能态的跃迁,它提供了有机体代谢及能量转化的重要信息,生物光子对生命系统内部的变化及外界环境的影响有高度的敏感性,生物光子的探测和分析能够揭示系统内部的细节变化,展示外界环境的微弱影响。本文就近年来生物光子辐射研究的热点与进展作一简要综述。     

生物光子辐射的研究进展

生物光子辐射来自生物分子从高能态向低能态的跃迁,它提供了有机体代谢及能量转化的重要信息,生物光子对生命系统内部的变化及外界环境的影响有高度的敏感性,生物光子的探测和分析能够揭示系统内部的细节变化,展示外界环境的微弱影响。本文就近年来生物光子辐射研究的热点与进展作一简要综述。     

Heat Stress Responses in Cultured Plant Cells : Heat Tolerance Induced by Heat Shock versus Elevated Growing Temperature

Using cultured pear (Pyrus communis cv Bartlett) cells, heat tolerance induced by heat shock was compared to that developed during growth at high temperature. After growth at 22°C, cells exposed to 38°C for 20 minutes (heat shock) showed maximum increased tolerance within 6 hours. Cells grown at 30°C developed maximum heat tolerance after 5 to 6 days; this maximum was well below that induced by heat shock. Heat shock-induced tolerance was fully retained at 22°C for 2 days and was only partly lost after 4 days. However, pear cells acclimated at 30°C lost all acquired heat tolerance 1 to 2 days after transfer to 22°C. In addition, cells which had been heat-acclimated by growth at 30°C showed an additional increase in heat tolerance in response to 39°C heat shock. The most striking difference between heat shock and high growth temperature effects on heat tolerance was revealed when tolerance was determined using viability tests based on different cell functions. Growth at 30°C produced a general hardening, i.e. increased heat tolerance was observed with all three viability tests. In contrast, significantly increased tolerance of heat-shocked cells was observed only with the culture regrowth test. The two types of treatment evoke different mechanisms of heat acclimation.     

Heat Shock Induced Change in Protein Ubiquitination in Chlamydomonas

Ubiquitin was purified from pea (Pisum sativum L.) and its antibodywas produced. Western blot analysis showed that the antibodycross-reacted with ubiquitins from a green alga Chlamydomonasreinhardtii, a brown alga Laminaria angustata and a red algaPorphyridium cruentum but not with ubiquitin from a blue-greenalga Synechococcus sp. In Chlamydomonas, the antibody also reactedwith some ubiquitinated proteins including 28- and 31-kDa polypeptides.The isoelectric points of Chlamydomonas ubiquitin and the 28-and 31-kDa ubiquitinated proteins were 8.0, 8.9 and 10.3, respectively.The ubiquitinated proteins, including the 28- and 31-kDa polypeptideswere detected after in vitro ATP-dependent ubiquitination ofChlamydomonas cell extract with ^l25I-labeled bovine ubiquitin.Heat treatment of Chlamydomonas cells (>40°C) causeddrastic increase of ubiquitinated proteins with high mol wt(>60kDa), and coordinated redistribution or decrease of otherubiquitinated proteins and free ubiquitin. Quantitative analysisrevealed that the 28- and 31-kDa ubiquitinated proteins showeddifferent responses against heat stress, i.e. the former beingmore sensitive than the latter. (Received July 10, 1988; Accepted October 4, 1988)     

绿豆和花生的超弱发光

对黄化绿豆幼苗先形态建成过程的超弱发光图象（延迟发光）的初步观察发现：见光培养40min后的绿豆幼苗即可探测到明显的延迟发光;见光时间越长,光诱导的延迟发光强度也越强。从绿豆和花生幼苗的趋弱发光图象来看,生长健壮的幼苗发光较强。其中茎尖和新生幼叶的延迟发光最强,上胚轴、子叶和下胚轴弯钩较强,下胚轴伸长部分次之,根部发光最弱。从不同发育阶段叶片的超弱发光图象来看,光合作用较强、新陈代谢旺盛的成熟叶片的超弱发光较强;光合作用和其它代谢过程相对较弱的叶片（伸展叶、老叶和幼叶）,其超弱发光强度相应较弱。而叶绿素提取液和失活绿叶观测不到超弱发光。此外,对超弱发光光谱的初步研究表明它很可能来自光合作用中叶绿素的发光。这些都暗示,植物的（诱导）超弱发光与光形态建成和光合作用等生长代谢过程密切相关。     

金属离子诱导高粱雄性不育系、保持系热激反应的研究

本试验以高粱雄性不育系和保持系为材料进行金属离子诱导应激反应的研究。结果表明CuSO_4溶液诱导高粱雄性不育系产生的应激反应明显,所用CuSO_4溶液最适浓度为250pmol/L,最适培养时间为4小时。ZnSO_4溶液诱导反应不明显。电泳分析和自显影检测出CuSO_4诱导产生新蛋白区带在3197A为9条,3197B为20条。但各蛋白带产生所需浓度和时间不完全相同,表明各种蛋白的基因表达是相互独立的,且这些基因的表达随发育而有变化。从分析处理后的4种酶的反应可以看出,其中细胞色素氧化酶有5条带,过氧化物酶反应灵敏,但只有2条带。通过CuSO_4处理与热激处理比较,推测3197A、3197B有其特殊的基因调控系统。从产生的可溶性蛋白或酶来看,CuSO_4能使3197A产生的应激蛋白趋向于3197B,说明两者具有相似之处。     

Heat Shock Protein Synthesis Induced by Methomyl in Maize (Zea mays L.) Seedlings

Exposure of plumules of intact maize seedlings (Zea mays L.) to S-methyl-N-[(methylcarbamoyl)-oxy]thioacetimidate (methomyl) represses synthesis of several polypeptides normally made under control conditions and induces synthesis of polypeptides similar to maize heat shock polypeptides (HSPs). Three of the methomyl-induced polypeptides (18 kilodaltons) are recognized by antibodies raised against 18 kilodalton maize heat shock polypeptides.     

热激蛋白70与热激反应

热激反应是细胞保护的最原始机制之一。近年来,越来越多的研究证明热激蛋白作为一种自然机制参与细胞保护,而热激蛋白70家族在其中起重要作用,从而成为恶劣条件、手术过程以及同病原体的斗争中器官保护的重要机制之一。     

热激蛋白90与热激应答

热激蛋白90(heat shock protein 90,HSP90)作为机体重要的分子伴侣之一,主要是维持机体内环境的稳态.在机体遭受内外界刺激时,体内氧化-抗氧化平衡失调诱发机体热激应答,诱导HSP90高表达来抵御刺激对机体造成的损伤.     

热激对水稻幼苗耐冷性及热激蛋白合成的诱导

萌发的水稻种子经42℃热激处理后其幼苗的耐冷性明显增强,膜伤害程度降低,脯氨酸含量增加,超氧物歧化酶(SOD)、过氧化氢酶(CAT)、过氧化物酶(POD)活性和抗氧化物质抗坏血酸含量增加,而膜脂过氧化的关键酶脂氧合酶(LOX)活性及其产物丙二醛(MDA)含量下降.并且热激诱导萌发的水稻胚合成78、70、64、60、46、38、24、17、16kD的热激蛋白(HSP),其中属于HSP70的内质网结合蛋白(BiP)的合成与水稻幼苗耐寒性的提高有关.     

水稻籽粒灌浆过程中超弱发光特性的研究

本实验对水稻籽粒灌浆过程中不同时期籽粒进行了超弱发光测定。实验结果表明：在整个灌浆过程中单粒发光量呈单峰曲线,在籽粒全部充实并且颜色由青转黄时,发光量最大;发光强度呈递减趋势;运用该技术有可能进行水稻不同品种间的比较和品种灌浆力强弱的筛选。     

Heat Shock Protein Produced by Helicobacter pylori

The cells of Helicobacter pylori were suspended in the medium containing³⁵S-methionine. After a heat shock of the cells at 42 C for 5, 10, and 30 min, the production of proteins was analyzed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and autoradiography. Out of many proteins produced by the cells, only 66 kDa protein production was dramatically increased by heat treatment. The N-terminal amino acid sequence of 66 kDa protein was quite similar to that of 62 kDa and 54 kDa proteins previously suggested as heat shock protein (HSP) of H. pylori based on the reaction with polyclonal and monoclonal antibodies against HSP 60 family proteins produced by other bacteria. Therefore, it was concluded that H. pylori produces the 66 kDa protein as its major heat shock protein which belongs to HSP 60 family.     

Induced Levels of Heat Shock Proteins in a dnaK Mutant of Lactococcus lactis

The bacterial heat shock response is characterized by the elevated expression of a number of chaperone complexes and proteases, including the DnaK-GrpE-DnaJ and the GroELS chaperone complexes. In order to investigate the importance of the DnaK chaperone complex for growth and heat shock response regulation in Lactococcus lactis, we have constructed two dnaK mutants with C-terminal deletions in dnaK. The minor deletion of 65 amino acids in the dnaKΔ2 mutant resulted in a slight temperature-sensitive phenotype. BK6, containing the larger deletion of 174 amino acids (dnaKΔ1), removing the major part of the inferred substrate binding site of the DnaK protein, exhibited a pronounced temperature-sensitive phenotype and showed altered regulation of the heat shock response. The expression of the heat shock proteins was increased at the normal growth temperature, measured as both protein synthesis rates and mRNA levels, indicating that DnaK could be involved in the regulation of the heat shock response in L. lactis. For Bacillus subtilis, it has been found (A. Mogk, G. Homuth, C. Scholz, L. Kim, F. X. Schmid, and W. Schumann, EMBO J. 16:4579–4590, 1997) that the activity of the heat shock repressor HrcA is dependent on the chaperone function of the GroELS complex and that a dnaK insertion mutant has no effect on the expression of the heat shock proteins. The present data from L. lactis suggest that the DnaK protein could be involved in the maturation of the homologous HrcA protein in this bacterium.     

Heat Shock–Induced Changes in the Respiration of the Yeast Saccharomyces cerevisiae

The incubation of Saccharomyces cerevisiaeat elevated temperature (45°C) stimulated the respiration of yeast cells and decreased their survival rate. The respiration-deficient mutant of this yeast was found to be more tolerant to the elevated temperature than the wild-type strain. At the same time, the cultivation of the wild-type strain in an ethanol-containing medium enhanced the respiration, catalase activity, and thermotolerance of yeast cells, as compared with their growth in a glucose-containing medium. It is suggested that the enhanced respiration of yeast cells at 45°C leads to an intense accumulation of reactive oxygen species, which may be one of the reasons for the heat shock–induced cell death.     

Heat Shock Induced Lipid Changes and Solute Leakage in Germinating Seeds of Pigeonpea

Heat shock (HS) reduced total lipid and phospholipid contents and their synthesis in germinating seeds of pigeonpea [Cajanus cajan (L.) Millspaugh]. Lipid peroxidation was also enhanced with increasing temperature and HS duration. HS influenced lipid metabolism to a higher extent at 45°C than at 40°C. This altered lipid metabolism and lipid peroxidation was associated with the loss of various solutes from the germinating seeds, and modification of growth and development. Pretreatment of germinating seeds at 40°C for 1 h or at 45°C for 10 min followed by incubation at 28°C for 3 h prior to 45°C for 2 h ameliorated solute leakage due to reduced lipid peroxidation and improvement in lipid content and membrane function.     

温度休克法诱导草履虫的同步分裂

运用细胞周期原理,采用温度休克法,对尾草履虫进行分裂周期同步化的研究,实验中草履虫经过3～5 h的处理后,就能观察到大量不同阶段的无性生殖横分裂状态,并获得了大量处于分裂阶段的草履虫.运用这种技术取材容易,获取率稳定,可达61%,可为细胞生理学等领域的研究提供大量的同步分裂个体.     

温度休克法诱导草履虫的同步分裂

运用细胞周期原理,采用温度休克法,对尾草履虫进行分裂周期同步化的研究,实验中草履虫经过3－5h的处理后,就能观察到大量不同阶段的无性生殖横分裂状态,并获得了大量处于分裂阶段的草履虫。运用这种技术取材容易,获取率稳定,可达61％,可为细胞生理学等领域的研究提供大量的同步分裂个体。