SDS-PAGE heat-shock protein profiles of environmental Aeromonas strains

Aeromonas microorganisms normally grow at temperatures between 5 degrees C and 45 degrees C and therefore should have high thermotolerance. Thus it was of interest to find out whether A. hydrophila, A. caviae and A. veronii biovar sobria serovars respond to abrupt temperature changes with a heat shock-like response. To this end the present study was undertaken to determine whether Aeromonas species exhibits a heat shock response to different temperatures and time factors. The response of Aeromonas serovars to 24 h and 48 h of thermal stress at 25 degrees C, 42 degrees C and 50 degrees C involved the synthesis of 12-18 heat shock proteins (HSPs) bands with molecular weights ranging between 83.5-103.9 kDa in the high HSP molecular mass and 14.5-12.0 as low molecular mass HSP. Electrophoretic analysis of the HSPs showed that the serovars do not cluster very tightly and also that they are distinct from each other.     

The role of oxidative stress in the induction of Drosophila heat-shock proteins

The role of oxidative stress in the induction of heat-shock proteins (HSPs) was studied in Drosophila Kc cells by comparing the effects of two different inducers, temperature stress and reoxygenation following a period of anoxia, on cellular respiration, thiol status, and the accumulation of HSPs. A heat shock from 25 to 37 degrees C caused a 60% increase in the rate of O2 uptake but caused little oxidative stress as indicated by a constant level of reduced glutathione, a slight increase in oxidized glutathione, and no change in protein sulfhydryls. Heat shock resulted in a pronounced accumulation of HSPs which was not inhibited by anoxic conditions. A different HSP inducer, reoxygenation following anoxia, resulted in an overall inhibition of respiration, the appearance of CN -insensitive O2 uptake, a 50% decrease in the level of reduced glutathione and a fourfold increase in the ratio of oxidized to reduced glutathione. Despite these indicators of oxidative stress, HSP synthesis was less pronounced than observed during heat shock and was not affected by antioxidants. Oxidative stress may induce HSP synthesis in some cases but is not responsible for HSP synthesis during a heat shock.     

Calcium is involved in regulation of the synthesis of HSPs in suspension-cultured sugar beet cells under hyperthermia

Exposure of plants to elevated temperatures induces a complex set of changes that enable plants to adapt following heat stress. In order to test the effect of Ca²⁺ on heat shock-induced changes in cell protein synthesis the incorporation of [ 35 S]methionine into protein was studied in cultured sugar beet ( Beta vulgaris L.) cells incubated in media containing different calcium concentrations. Heat shock inhibited the synthesis of non-heat shock proteins (non-HSPs) and promoted the synthesis of a set of HSPs, typical of plants. The synthesis of non-HSPs was greatly inhibited by external Ca²⁺ removal by treatment of the cells with ethylene glycol-bis( β -aminoethylether)- N,N,N',N'- tetraacetic acid. In contrast, extracellular Ca²⁺ appeared not to be strictly required for the de novo production of HSPs, but this cation exerted different effects on the synthesis of individual HSPs. Cell injury increased if the cells were exposed simultaneously to high temperature and Ca²⁺-deficient medium. Recovery of HSP synthesis and reduced cell injury were observed after addition of exogenous calcium to Ca²⁺-depleted cells. These findings are consistent with a Ca²⁺ requirement for the survival of the cells under heat shock, and likely for the development of cell thermotolerance.     

Tissue-specific expression of sunflower heat shock proteins in response to water stress

Accumulation of mRNA and synthesis of low-molecular-weight heat shock proteins (LMW HSPs) was investigated in water-stressed sunflower, under experimental conditions resulting in little or no thermal stress. Using probes and antibodies derived from developmentally expressed LMW HSPs, it was shown that homologous mRNAs and proteins accumulate in the stem and root of water-stressed plants. This expression is quantitatively comparable with the response to heat shock: protein and mRNA accumulate to similar, high, levels and persist for comparable times during recovery from either environmental stress. However, it is shown that LMW HSPs with different molecular weights and isoelectric points are expressed in response to heat shock or water stress. Furthermore in situ localizations show a differential tissue-specificity for the water-stress- and heat-shock-induced LMW HSPs. Whereas the latter are localized mostly around the xylem vessels in the stem, the water-stress-induced proteins accumulate in the fascicular and interfascicular cambium. The possible functional implications for this specific expression are discussed.     

Heat shock proteins: essential proteins for apoptosis regulation

Many different external and intrinsic apoptotic stimuli induce the accumulation in the cells of a set of proteins known as stress or heat shock proteins (HSPs). HSPs are conserved proteins present in both prokaryotes and eukaryotes. These proteins play an essential role as molecular chaperones by assisting the correct folding of nascent and stress-accumulated misfolded proteins, and by preventing their aggregation. HSPs have a protective function, that is they allow the cells to survive to otherwise lethal conditions. Various mechanisms have been proposed to account for the cytoprotective functions of HSPs. Several of these proteins have demonstrated to directly interact with components of the cell signalling pathways, for example those of the tightly regulated caspase-dependent programmed cell death machinery, upstream, downstream and at the mitochondrial level. HSPs can also affect caspase-independent apoptosis-like process by interacting with apoptogenic factors such as apoptosis-inducing factor (AIF) or by acting at the lysosome level. This review will describe the different key apoptotic proteins interacting with HSPs and the consequences of these interactions in cell survival, proliferation and apoptotic processes. Our purpose will be illustrated by emerging strategies in targeting these protective proteins to treat haematological malignancies.     

Influence of Temperature Stress on in Vitro Fertilization and Heat Shock Protein Synthesis in Maize (Zea mays L.) Reproductive Tissues

This study was conducted to investigate the response of maize (Zea mays) male and female mature reproductive tissues to temperature stress. We have tested the fertilization abilities of the stressed spikelets and pollen using in vitro pollination-fertilization to determine their respective tolerance to stress. The synthesis of heat shock proteins (HSPs) was also analyzed in male and female tissues using electrophoresis of ³⁵S-labeled proteins and fluorography, to establish a relationship between the physiological and molecular responses. Pollen, spikelets, and pollinated spikelets were exposed to selected temperatures (4, 28, 32, 36, or 40°C) and tested using an in vitro fertilization system. The fertilization rate is highly reduced when pollinated spikelets are exposed to temperatures over 36°C. When pollen and spikelets are exposed separately to temperature stress, the female tissues appear resistant to 4 hours of cold stress (4°C) or heat stress (40°C). Under heat shock conditions, the synthesis of a typical set of HSPs is induced in the female tissues. In contrast, the mature pollen is sensitive to heat stress and is responsible for the failure of fertilization at high temperatures. At the molecular level, no heat shock response is detected in the mature pollen.     

昆虫的热休克反应和热休克蛋白

热休克（热激heatshock）是指短暂、迅速地向高温转换所诱导出的一种固定的应激反应。诱导该反应的温度在种与种之间有所不同。热休克反应最明显的特征是：伴随着正常蛋白质合成的抑制,一部分特殊蛋白质的诱导和表达增加,即为热休克蛋白（heatshockproteins,HSPs）。尽管热休克蛋白的合成也能被其它形式的应激反应所诱导,将它们认为是应激蛋白可能更恰当,但人们习惯上仍将这类蛋白质称为热休克蛋白。由于热休克反应和热休克蛋白是在果蝇（Drosophiliamelanogaster）中最初发现的,故在昆虫中,特别是果蝇等双翅目昆虫中研究得较深入…     

Heat shock proteins and effects of heat shock in plants

Soybean seedlings when exposed to a heat shock respond in a manner very similar to that exhibited by cultured cells, and reported earlier [2]. Maximum synthesis of heat shock proteins (HSPs) occurs at 40C. The heat shock response is maintained for a relatively short time under continuous high temperature. After 2.5 hr at 40 C the synthesis of HSPs decreases reaching a very low level by 6 hr. The HSPs synthesized by cultured cells and seedlings are identical and there is a large degree of similarity in HSPs synthesized between the taxonomically widely separated species, soybean and corn. Storage protein synthesis in the developing soybean embryo is not inhibited but is actually stimulated during a heat shock, unlike most other non-HSPs, whose synthesis is greatly reduced. Seedlings respond differently to a gradual increase in temperature than they do a sudden heat shock. There is an upward shift of several degrees in the temperature at which maximum protein synthesis occurs and before it begins to be inhibited. In addition, there appears to be a protection of normal protein synthesis from heat shock inhibition when the temperature increase is gradual. An additional function of the heat shock phenomenon might be the protection of seedlings from death caused by extreme heat stress. The heat shock response appears to have relevance to plants in the field.     

Molecular responses of plants to an increased incidence of heat shock

Abstract. Climatic change as a result of the greenhouse effect is widely predicted to increase mean temperatures globally and, in turn, increase the frequency with which plants are exposed to heat shock conditions, particularly in the semi-arid tropics. The consequences of extreme high-temperature treatments on plants have been considered, particularly in relation to the synthesis of heat shock proteins (HSPs) and the capacity to acquire thermotolerance. The heat shock response is described using results obtained with seedlings of the tropical cereals, sorghum ( Sorghum bicolor ) and pearl millet ( Pennisetum glaucum ). A gradual temperature increase, as would occur in the field, is sufficient to induce thermotolerance. The synthesis of HSPs is a transient phenomenon and ceases once the stress is released. Despite the persistence of the HSPs themselves, de novo synthesis of HSPs is required for the induction of thermotolerance each time high temperatures are encountered. The effect of a repeated, diurnal heat shock was investigated and genotypic differences found in the ability to induce the heat shock response repeatedly.     

Application of heat shock proteins as stress markers in aquatic organisms using endemic Baikal amphipods as an example

When heat shock proteins (HSPs) are used as biomarkers in monitoring studies of aquatic ecosystems, it is necessary to take into account the specificity of synthesis of these proteins in various organisms. This especially applies to endemic species and species with narrow ranges of adaptation for specific conditions in certain water bodies. In this study, we assessed the possibility to use HSPs as molecular stress markers in species with a narrow niche breadth using endemic Baikal amphipods (Crustacea, Amphipoda) as an example. The effect of stress induced by toxicants and temperature has been assessed. Proteins of families HSP70 and low-molecular-weight HSP related to alpha-crystallins were used as biomarkers. Temperature- and toxicant-induced stresses induced low-molecular-weight HSP synthesis in the endemic amphipod species studied. However, induction of HSP70 synthesis in the same species after temperature stress has not been detected. The specificity of synthesis of HSP70 is discussed. The results obtained in this study suggest that low-molecular-weight HSPs can be used as stress markers in Baikal species and species with a narrow niche breadth.     

Application of heat shock proteins as stress markers in aquatic organisms using endemic Baikal amphipods as an example

When heat shock proteins (HSPs) are used as biomarkers in monitoring studies of aquatic ecosystems, it is necessary to take into account the specificity of synthesis of these proteins in various organisms. This especially applies to endemic species and species with narrow ranges of adaptation for specific conditions in certain water bodies. In this study, we assessed the possibility to use HSPs as molecular stress markers in species with a narrow niche breadth using endemic Baikal amphipods (Crustacea, Amphipoda) as an example. The effect of stress induced by toxicants and temperature has been assessed. Proteins of families HSP70 and lowmolecular-weight HSP related to α-crystallins were used as biomarkers. Temperature-and toxicant-induced stresses induced low-molecular-weight HSP synthesis in the endemic amphipod species studied. However, induction of HSP70 synthesis in the same species after temperature stress has not been detected. The specificity of synthesis of HSP70 is discussed. The results obtained in this study suggest that low-molecular-weight HSPs can be used as stress markers in Baikal species and species with a narrow niche breadth.     

Heat and cold shock protein synthesis in arctic and temperate strains of rhizobia.

We compared heat shock proteins (HSPs) and cold shock proteins (CSPs) produced by different species of Rhizobium having different growth temperature ranges. Several HSPs and CSPs were induced when cells of three arctic (psychrotrophic) and three temperate (mesophilic) strains of rhizobia were shifted from their optimal growth temperatures (arctic, 25 degrees C; temperate, 30 degrees C) to shock temperatures outside their growth temperature ranges. At heat shock temperatures, three major HSPs of high molecular weight (106,900, 83,100, and 59,500) were present in all strains for all shock treatments (29, 32, 36.4, 38.4, 40.7, 41.4, and 46.4 degrees C), with the exception of temperate strains exposed to 46.4 degrees C, in which no protein synthesis was detected. Cell survival of arctic and temperate strains decreased markedly with the increase of shock temperature and was only 1% at 46.4 degrees C. Under cold shock conditions, five proteins (52.0, 38.0, 23.4, 22.7, and 11.1 kDa) were always present for all treatments (-2, -5, and -10 degrees C) in arctic strains. Among temperate strains, five CSPs (56.1, 37.1, 34.4, 17.3, and 11.1 kDa) were present at temperatures down to 0 degrees C. The 34.4- and the 11.1-kDa components were present in all temperate strains at -5 degrees C and in one strain at -10 degrees C. Survival of all strains decreased with cold shock temperatures but was always higher than 50%. These results show that rhizobia can synthesize proteins at temperatures not permissive for growth. In all shock treatments, no correspondence between the number of HSPs or CSPs produced and rhizobial survival was found.(ABSTRACT TRUNCATED AT 250 WORDS)     

induction of heat shock response and acquisition of thermotolerance in callus cultures of Gerbera jamesonii

Summary The heat shock (HS) response in callus cultures of the ornamental plant Gerbera jamesonii H. Bolus var. hybrida was analyzed. A HS at 35° C or 40° C for 4 h induced (a) the synthesis of several heat shock proteins (HSPs), especially in the small molecular weight range and some spots corresponding to HSP70 components, and (b) an increase in the steady state levels of some specific mRNAs. At the nonstressing temperature (26° C), a sustainable level of translation for HSP70 was indeed carried out, as confirmed by immunological analysis with a monoclonal antibody against cotton HSP70. The steady state levels of mRNAs measured before and after a HS by Northern hybridization showed an increase with the heterologous probes HSP17.4, HSP17.6, and HSP21, whereas the probes HSC70 and HSP70 did not show any difference between the levels of control and HS-mRNAs. A pretreatment at 35° C, which induced a set of HSPs in the callus cultures, decreased the cell damage upon exposure to a temperature of 45° C as determined either with a regrowth test or by the tetrazolium reduction assay. Typically, as with the whole plants, callus of Gerbera jamesonii possessed the ability to respond to HS both by inducing HSPs and by developing an acquired thermotolerance.     

Heat and cold shock protein synthesis in arctic and temperate strains of rhizobia.

We compared heat shock proteins (HSPs) and cold shock proteins (CSPs) produced by different species of Rhizobium having different growth temperature ranges. Several HSPs and CSPs were induced when cells of three arctic (psychrotrophic) and three temperate (mesophilic) strains of rhizobia were shifted from their optimal growth temperatures (arctic, 25 degrees C; temperate, 30 degrees C) to shock temperatures outside their growth temperature ranges. At heat shock temperatures, three major HSPs of high molecular weight (106,900, 83,100, and 59,500) were present in all strains for all shock treatments (29, 32, 36.4, 38.4, 40.7, 41.4, and 46.4 degrees C), with the exception of temperate strains exposed to 46.4 degrees C, in which no protein synthesis was detected. Cell survival of arctic and temperate strains decreased markedly with the increase of shock temperature and was only 1% at 46.4 degrees C. Under cold shock conditions, five proteins (52.0, 38.0, 23.4, 22.7, and 11.1 kDa) were always present for all treatments (-2, -5, and -10 degrees C) in arctic strains. Among temperate strains, five CSPs (56.1, 37.1, 34.4, 17.3, and 11.1 kDa) were present at temperatures down to 0 degrees C. The 34.4- and the 11.1-kDa components were present in all temperate strains at -5 degrees C and in one strain at -10 degrees C. Survival of all strains decreased with cold shock temperatures but was always higher than 50%. These results show that rhizobia can synthesize proteins at temperatures not permissive for growth. In all shock treatments, no correspondence between the number of HSPs or CSPs produced and rhizobial survival was found.(ABSTRACT TRUNCATED AT 250 WORDS)     

Heat Shock Proteins in Two Lines of Zea mays L. That Differ in Drought and Heat Resistance

Synthesis of heat shock proteins (HSPs) in the leaves of a drought- and heat-resistant (line ZPBL 1304), and a drought- and heat-sensitive (line ZPL 389) line of maize (Zea mays L.) was studied under two environmental stress treatments: (a) soil drying and high temperature and (b) high temperature. In the first treatment 13-day-old plants were exposed to 7-day soil drying followed by high temperature stress (45°C), and in the second treatment 20-day-old plants were exposed to high temperature stress (45°C). Second leaves were labeled with [³⁵S]methionine. During the labeling period line ZPBL 1304 showed no signs of leaf dehydration under soil drying and high temperature stress conditions. In contrast, line ZPL 389 was dehydrated 23%, as determined by relative water content. Incorporation of [³⁵S]methionine into protein was greater in the resistant than in the sensitive line in both treatments. The pattern of synthesis of HSPs in the two lines was similar in treatments 1 and 2. Both lines synthesized a high molecular mass set and a low molecular mass set of HSPs. Proteins from both sets from both lines of maize appeared similar to each other, with respect to the molecular mass. Heated plants of the drought- and heat-resistant line ZPBL 1304 synthesized a band of HSP(s) of approximately 45 kilodaltons which was not found in heated plants of the drought and heat sensitive line ZPL 389. This is the first report on qualitative intraspecific difference in the synthesis of HSPs in maize.     

Heat shock proteins: endogenous modulators of apoptotic cell death

The highly conserved heat shock proteins (HSPs) accumulate in cells exposed to heat and a variety of other stressful stimuli. HSPs, which function mainly as molecular chaperones, allow cells to adapt to gradual changes in their environment and to survive in otherwise lethal conditions. The events of cell stress and cell death are linked and HSPs induced in response to stress appear to function at key regulatory points in the control of apoptosis. HSPs include antiapoptotic and proapoptotic proteins that interact with a variety of cellular proteins. Their expression level can determine the fate of the cell in response to a death stimulus, and apoptosis-inhibitory HSPs, in particular HSP27 and HSP70, may participate in carcinogenesis. This review summarizes apoptosis-regulatory function of HSPs.     

Effects of hyperthermia on spermatogenesis, apoptosis, gene expression, and fertility in adult male mice.

Testicular heat shock was used to characterize cellular and molecular mechanisms involved in male fertility. This model is relevant because heat shock proteins (HSPs) are required for spermatogenesis and also protect cells from environmental hazards such as heat, radiation, and chemicals. Cellular and molecular methods were used to characterize effects of testicular heat shock (43 degrees C for 20 min) at different times posttreatment. Mating studies confirmed conclusions, based on histopathology, that spermatocytes are the most susceptible cell type. Apoptosis in spermatocytes was confirmed by TUNEL, and was temporally correlated with the expression of stress-inducible Hsp70-1 and Hsp70-3 proteins in spermatocytes. To further characterize gene expression networks associated with heat shock-induced effects, we used DNA microarrays to interrogate the expression of 2208 genes and thousands more expression sequence tags expressed in mouse testis. Of these genes, 27 were up-regulated and 151 were down-regulated after heat shock. Array data were concordant with the disruption of meiotic spermatogenesis, the heat-induced expression of HSPs, and an increase in apoptotic spermatocytes. Furthermore, array data indicated increased expression of four additional non-HSP stress response genes, and eight cell-adhesion, signaling, and signal-transduction genes. Decreased expression was recorded for 10 DNA repair and recombination genes; 9 protein synthesis, folding, and targeting genes; 9 cell cycle genes; 5 apoptosis genes; and 4 glutathione metabolism genes. Thus, the array data identify numerous candidate genes for further analysis in the heat-shocked testis model, and suggest multiple possible mechanisms for heat shock-induced infertility.     

Heat shock induced changes in the gene expression of terminally differentiating avian red blood cells

Reticulocytes, purified from the blood of quail and chickens recovering from anaemia, respond to heat shock by the new and (or) enhanced synthesis of heat-shock protein (HSPs) with relative molecular masses of greater than 400,000, 90,000, 70,000, and 26,000 (quail) or 24,000 (chicken) and the depressed synthesis of many proteins normally produced at a control temperature. The synthesis of these HSPs is noncoordinate since the expression of each protein depends upon the particular temperature and duration of the time at that temperature. Separation of proteins from quail reticulocytes into Triton X-100 soluble and insoluble fractions demonstrates that the 70,000 and 26,000 Da HSPs are found in both fractions, whereas the greater than 400,000 and 90,000 Da HSPs are located only in the detergent-soluble fraction. Triton X-100 fractionation also reveals that there are three isoelectric variants of the 70,000 Da HSP and that they are constitutively synthesized and selectively partitioned between cellular compartments. Heat shock induced synthesis of the 90,000, 70,000, and 26,000 Da quail HSPs is prevented by actinomycin D, while enhanced synthesis of the greater than 400,000 Da HSP is unaffected by this inhibitor. These results demonstrate that nucleated, terminally differentiating avian red blood cells are capable of responding to heat stress by rapid changes in their highly restricted "program" of gene expression.