Isoform pattern of inducible HSP 70 in the rat myocardium after heat shock]

The hsp 70 content was measured in the myocardium of a control rat group, in the group of rats 24 hours following a heat shock and in the group of rats 48 hours after a heat shock. In 24 hours after the heat shock, a major inducible hsp 70 with molecular weight of 71 kDa and pI about 5.8 occurred which was utterly absent in myocardial cytosol from control animals. In addition, there was an increase in polypeptide fraction with molecular weight of 73 kDa and pI about 5.6 (HSX73). In 48 hours after the heat shock, first the inducible hsp 70 with molecular weight of 71 kDa and pI about 5.8 disappeared which was found in 24 hours; secondly, HSX73 decreased to the control level and, thirdly, several isoforms pronouncedly accumulated with molecular weight of about 71 kDa and pI ranging from 5.9 to 6.3. Thus, the isoform composition of stress proteins induced by heat shock strongly depends on the time after the stress exposure. Furthermore, the accumulation of more acidic isoforms precedes the accumulation of alkaline ones.     

Adaptation of the body to stress effects increases resistance of nuclear DNA of cardiac cells due to accumulation of heat shock proteins in the nucleus]

It was shown that adaptation to stress exposure increased the resistance of nuclear DNA in myocardial cells to the damaging action of exogenous one-chain DNA (50 micrograms/ml). This protective effect was accompanied by a pronounced accumulation of heat shock proteins (hsp) 70 in nucleoplasm of myocardial cells from adapted animals. Possible mechanism of the DNA protective effect of adaptation and the role of hsp 70 are under discussion.     

Expression patterns and organization of the hsp70 genes correlate with thermotolerance in two congener endemic amphipod species (Eulimnogammarus cyaneus and E. verrucosus) from Lake Baikal

We studied various aspects of heat‐shock response with special emphasis on the expression of heat‐shock protein 70 (hsp70) genes at various levels in two congener species of littoral endemic amphipods (Eulimnogammarus cyaneus and E. verrucosus) from Lake Baikal which show striking differences in their vertical distribution and thermal tolerance. Although both the species studied demonstrate high constitutive levels of Hsp70, the thermotolerant E. cyaneus exhibited a 5‐fold higher basal level of Hsp70 proteins under normal physiological conditions (7 °C) and significantly lower induction of Hsp70 after temperature elevation compared with the more thermosensitive E. verrucosus. We isolated the hsp70 genes from both species and analysed their sequences. Two isoforms of the cytosolic Hsp70/Hsc70 proteins were detected in both species under normal physiological conditions and encoded by two distinct hsp/hsc70 family members. While both Hsp70 isoforms were synthesized without heat shock, only one of them was induced by temperature elevation. The observed differences in the Hsp70 expression patterns, including the dynamics of Hsp70 synthesis and threshold of induction, suggest that the increased thermotolerance in E. cyaneus (compared with E. verrucosus) is associated with a complex structural and functional rearrangement of the hsp70 gene family and favoured the involvement of Hsp70 in adaptation to fluctuating thermal conditions. This study provides insights into the molecular mechanisms underlying the thermal adaptation of Baikal amphipods and represents the first report describing the structure and function of the hsp70 genes of endemic Baikal species dwelling in thermally contrasting habitats.     

The effects of heat shock and acclimation temperature on hsp70 and hsp30 mRNA expression in rainbow trout: in vivo and in vitro comparisons

Heat shock (25° C) of 10° C-acclimated rainbow trout Oncorhynchus mykiss led to increases in heat shock protein 70 (hsp70) mRNA in blood, brain, heart, liver, red and white muscle, with levels in blood being amongst the highest. Hsp30 mRNA also increased with heat shock in all tissues with the exception of blood. When rainbow trout blood was heat shocked in vitro , both hsp70 and hsp30 mRNA increased significantly. In addition, these in vitro experiments demonstrated that blood from fish acclimated to 17° C water had a lower hsp70 mRNA heat shock induction temperature than did 5° C acclimated fish (20 v. 25° C). The hsp30 mRNA induction temperature (25° C), however, was unaffected by thermal acclimation. While increases in hsp70 mRNA levels in blood may serve as an early indicator of temperature stress in fish, tissue type, thermal history and the particular family of hsp must be considered when evaluating stress by these molecular means.     

Effect of prenatal hypoxia on heat stress-mediated cardioprotection in adult rat heart

Fetal programming has profound effects on cardiovascular function in later adult life. We tested the hypothesis that chronic hypoxic exposure during fetal development downregulates endogenous cardioprotective mechanisms in adult rats. Time-dated pregnant rats were divided between normoxic and hypoxic (10.5% O2 from days 15 to 21 of gestation) groups. The male progeny were studied at 2 mo of age. Rats were subjected to heat stress (42 degrees C for 15 min). After 24 h, hearts were excised and subjected to 30 min of global ischemia and 1 h of reperfusion. Prenatal hypoxia did not change adult rat body weight and heart weight, but significantly increased the cross-sectional area of a left ventricular (LV) myocyte. Heat stress significantly improved postischemic recovery of LV function in normoxic control rats, but not in prenatally hypoxic rats. The infarct size in the LV resulting from ischemia-reperfusion was reduced by the heat stress pretreatment in control rats, but not in prenatally hypoxic rats. In accordance, heat stress significantly increased LV myocardial content of heat shock protein 70 only in normoxic control rats. In addition, there was a significant decrease in the LV myocardial content of the PKC-epsilon isoform in prenatally hypoxic rats compared with control rats. We conclude that prenatal hypoxia causes in utero programming of hsp70 gene in the LV, leading to an inhibition of its response to heat stress and a loss of cardioprotection in later adult life.     

HSC70 protein of human blood mononuclears as a sign of adaptation under normobaric hypoxia training

We investigated two isoforms of heat shock protein 70 kDa: HSP70 and HSC70, in the human blood mononuclears under normobaric hypoxia training. It was shown that hypoxia regimen does not lead to manifestation of stress but exerts activation of the organism. The obtained organism adaptation is achieved with a little cost that is confirmed by absence of HSP70 content increase. HSC70 content in the blood mononuclears was increased in most case up to 1.5-2.0 fold. HSC70 displays itself as a sign of adaptation. We connect the increase of HSC70 with mitochondria biogenesis which is given a leading importance under adaptation of aerobic organism cells to hypoxia.     

Heat shock protein (hsp70) expression and thermal tolerance in sublethally heat-shocked eastern oysters Crassostrea virginica infected with the parasite Perkinsus marinus

To investigate whether sublethal heat shock protects Perkinsus marinus (Dermo)-infected oysters Crassostrea virginica from lethal heat stress, and the effects of P. marinus infection on sublethal heat shock response, oysters were first experimentally challenged with P. marinus. Then, when infections in oysters progressed to moderate levels (parasite burden = 10(4) to 10(5) cells g(-1) wet tissue weight), oysters were treated with a sublethal heat shock at 40 degrees C for 1 h (heat shock + Dermo challenge). Other treatment groups included heat-shocked, unchallenged (non-P. marinus challenged) oysters and non-heat-shocked, P. marinus-challenged and -unchallenged oysters. Thermal tolerance was compared among these treatments by administering a lethal heat treatment at 44 degrees C for 1 h, 7 d after sublethal heat shock. Sublethal heat shock enhanced survival to lethal heat treatment in both P. marinus-challenged and -unchallenged oysters. Although levels of hsp70 isoforms (hsp69 and hsp72) did not vary significantly by heat shock or infection with P. marinus, responses due to these treatments were apparent when comparing hsp70 levels within infected and uninfected oysters. Infection enhanced expression of hsp69, regardless of whether oysters were heat shocked or not. In uninfected oysters, hsp72 increased due to heat shock 2 and 7 d post heat shock. Overall, this study demonstrates that heat shock can improve survival in oysters, even in oysters infected with P. marinus. Expression of hsp70 varied among isoforms after sublethal and lethal heat shocks and in infected and uninfected oysters. The heat shock response was not negatively affected by P. marinus infection.     

Candidate genes and thermal phenotypes: identifying ecologically important genetic variation for thermotolerance in the Australian Drosophila melanogaster cline

Clinal variation in traits often reflects climatic adaptation; in Drosophila melanogaster clinal variation provides an opportunity to link variation in chromosomal inversions, microsatellite loci and various candidate genes to adaptive variation in traits. We undertook association studies with crosses from a single population of D. melanogaster from eastern Australia to investigate the association between genetic markers and traits showing clinal variation. By genotyping parents and phenotyping offspring, we minimized genotyping costs but had the power to detect association between markers and quantitative traits. Consistent with prior studies, we found strong associations between the clinal chromosomal inversion In(3R)Payne and markers within it, as well as among these markers. We also found an association between In(3L)Payne and one marker located within this inversion. Of the five predicted associations between markers and traits, four were detected (increased heat, decreased cold resistance and body size with the heat shock gene hsr-omega S, increased cold resistance with the inversion In(3L)Payne), while one was not detected (heat resistance and the heat shock gene hsp68). In a set of eight exploratory tests, we detected one positive association (between hsp23a and heat resistance) but no associations of heat resistance with alleles at the hsp26, hsp83, Desat 2, alpha-Gpdh, hsp70 loci, while cold resistance was not associated with Frost and Dca loci. These results confirm interactions between hsr-omega and thermal resistance, as well as between In(3L)Payne and cold resistance, but do not provide evidence for associations between thermal responses and alleles at other clinically varying marker genes.     

The role of HSP70 and Ca(2+)-pump from the myocardial sarcoplasmic reticulum in cardioprotective effects during adaptation to physical load in rats

In the course of adaptation to exercise, enhanced resistance of isolated heart against ischemia and reperfusion correlated with accumulation of cytoprotective proteins of the HSP70 family and increased potency of sarcoplasmic reticulum (SR) Ca2+ pump in the rat myocardium. Blockade of the HSP70 synthesis with guercetin prevented development of protection of the heart against ischemia and reperfusion. In the course of the adaptation, the increased resistance of the Ca2+ pump against detrimental factors preceded its potentiation. The findings suggest that the HSP70 accumulation and increased potency and resistance of the SR Ca2+ transport system in the myocardium are important mechanisms of adaptive protection of the heart.     

Ascorbic acid decreases heat shock protein 70 and plasma corticosterone response in broilers (Gallus gallus domesticus) subjected to cyclic heat stress

It is known that ascorbic acid (AA) supplementation can ameliorate the chicken's responses to heat stress. The influence of AA on heart heat shock protein 70 (hsp70) and plasma corticosterone (CS) was evaluated in young male broiler chickens fed either no AA (N-AA) or 500 mg AA /kg (AA) and exposed to cyclic high temperatures (21 to 30 to 21 degrees C) over a 3.5 h period on three consecutive days. Dietary AA supplementation elevated plasma AA and maintained it at high levels after heating, but in N-AA birds, only heat elevated plasma AA. In N-AA fed chickens, plasma CS was elevated and was further increased by heat stress as compared with AA-fed birds. Heart hsp70 expression was greater in N-AA-fed chickens compared to AA-fed chickens, and heat stress further elevated hsp70 in both N-AA- and AA-fed birds. The hsp70 increase after heat was two-fold greater in N-AA- vs. AA-fed birds. Plasma CS and heart hsp70 were positively correlated, plasma AA and heart hsp70 were negatively correlated, and plasma CS and AA were negatively correlated. It was concluded that chickens experience a less severe stress response after exposure to high temperatures when they are provided dietary AA.     

Opposite effects on antioxidant enzymes of adaptation to continuous and intermittent hypoxia]

Adaptation to continuous hypoxia under mid-mountain conditions (altitude 2100 m) decreases the content of lipid peroxidation products and the activity of superoxide dismutase and catalase in rat heart, liver, and brain, with a concomitant decline in the resistance to reperfusion arrhythmias. On the contrary, adaptation to intermittent hypoxia in the altitude chamber increases the activity of the antioxidant enzymes in the same organs, while the content of peroxidation products remains normal; at the same time, the heart becomes more resistant to reperfusion arrhythmias. The mechanism is discussed that ensures enhanced antioxidant protection in adaptation to intermittent hypoxia.     

Expression of 70 kDa heat shock proteins in antarctic and New Zealand notothenioid fish

The cold and constant water temperature of the Southern Ocean surrounding Antarctica provides a natural laboratory to address questions of temperature adaptation in marine organisms. In this study, endogenous levels and the number of isoforms of the 70 kDa heat shock protein multigene family (hsp70) of Antarctic and cold temperate notothenioid fishes were determined by SDS-polyacrylamide gel electrophoresis and Western blotting. Tissues from three Antarctic Trematomus congeners had significantly lower levels of 70 kDa Hsp isoforms than their temperate confamilial from New Zealand waters. However, these two thermally disparate sets of fish did not differ in number or pattern of 70 kDa Hsp isoforms expressed under normal physiological conditions. Additionally, levels of 70 kDa Hsp isoforms in specimens of one Antarctic species, Trematomus bernacchii, acclimated to 4 degrees C were significantly higher than non-acclimated conspecifics, indicating a direct effect of temperature on Hsp expression in this species. This study shows that constitutive expression of some members of the 70 kDa Hsp multigene family have been maintained, despite the absence of environmental heat stress for at least 2.5 million years.     

Variation in heat shock proteins within tropical and desert species of poeciliid fishes

The 70-kilodalton heat shock protein (hsp70) family of molecular chaperones, which contains both stress-inducible and normally abundant constitutive members, is highly conserved across distantly related taxa. Analysis of this protein family in individuals from an outbred population of tropical topminnows, Poeciliopsis gracilis, showed that while constitutive hsp70 family members showed no variation in protein isoforms, inducibly synthesized hsp70 was polymorphic. Several species of Poeciliopsis adapted to desert environments exhibited lower levels of inducible hsp70 polymorphism than the tropical species, but constitutive forms were identical to those in P. gracilis, as they were in the confamilial species Gambusia affinis. These differences suggest that inducible and constitutive members of this family are under different evolutionary constraints and may indicate differences in their function within the cell. Also, northern desert species of Poeciliopsis synthesize a subset of the inducible hsp70 isoforms seen in tropical species. This distribution supports the theory that ancestral tropical fish migrated northward and colonized desert streams; the subsequent decrease in variation of inducible hsp70 may have been due to genetic drift or a consequence of adaptation to the desert environment. Higher levels of variability were found when the 30- kilodalton heat shock protein (hsp30) family was analyzed within different strains of two desert species of Poeciliopsis and also in wild-caught individuals of Gambusia affinis. In both cases the distribution of hsp30 isoform diversity was similar to that seen previously with allozyme polymorphisms.      

Adaptation to heat of cardiomyoblasts in culture protects them against heat shock: role of nitric oxide and heat shock proteins

Dosed adaptation to environmental factors is an efficient non-drug means for increasing the resistance of organs or the body as a whole. We demonstrated earlier that nitric oxide (NO) plays an important role in adaptive defense of the organism, in particular due to activation of heat shock protein (HSP) synthesis. A key question remained open—to what extent the formation of adaptive defense depends on central mechanisms and to what extent on the intracellular mechanisms immediately responding to the adapting factor, and whether the NO-dependent activation of HSP synthesis plays a role in adaptation of isolated cells. In the present study we looked into the possibility of producing a protective effect of adaptation to heat in cell culture. A 6-day adaptation to heat limited to 17% the decrease in metabolic activity induced by heat shock in H9c2 cardiomyoblasts. The development of adaptation was associated with increased NO production. Treatment of cells with the inhibitor of NO synthase L-NNA (100 M) prevented the development of adaptive protection. Adaptation of cell culture enhanced synthesis of HSP70 but not HSP27. Blockade of HSP70 synthesis with quercetin (50 M) left unchanged the protective effect of adaptation. Inhibition of NO synthesis restricted the adaptation-induced HSP70 synthesis. Therefore, the formation of adaptation at the cell level may result from a direct action of an environmental factor without participation of neurohumoral factors. Such adaptation involves NO-dependent mechanisms divorced from the activation of HSP70 synthesis.