The synthesis of heat shock proteins (hsps) at normal physiological and elevated temperatures has been correlated with the natural adaptation of an organism to heat in nine lizard species studied. These species differ drastically by their adaptation to elevated temperature and represent a spectrum of forms isolated from various geographical regions of the Union of Soviet Socialist Republics. The synthesis of hsps belonging to the hsp7O family and their correspondent mRNAs have been compared at different temperature regimes. This analysis has shown that lizards inhabiting the Middle Asia deserts are characterized by a higher content of hsp7O-like proteins at normal physiological temperatures (2-to 5-fold differences) when compared with the forms from central and northern regions of the European part of the Union of Soviet Socialistic Republics. Analysis of hsp7O mRNA at different temperatures substantiated these observations, showing evident correlation between adaptation of a given form to hyperthermia and the quantity of hsp7O mRNA in the cells under non-heat-shock conditions. The results obtained with a wide spectrum of ecologically different lizard species, coupled with other relevant data, enable us to propose a general rule applicable to poikilothermic organisms. This rule postulates the direct correlation between the characteristic temperature of the ecological niche of a given species and the amount of hsp7O-like proteins in the cells at normal temperature.Heat or other environmental stresses have been shown to induce the synthesis of a family of proteins, the so-called heat shock proteins (hsps), in a wide variety of cells from yeast to mammalian systems (for reviews, see refs. 1-3). Recent work has focused on the role of hsps in the assembly, folding, and transport of other cellular proteins under different conditions. The level of these special activities of hsps, often termed "chaperonins", depends on the state of the general translational machinery of the cell (4-6). One of the more interesting aspects of thermal biology in different systems is the interrelation between the induction of hsp synthesis and the development of thermoresistance. Hsps are thought to protect cells from the toxic effects of short-term environmental stress (1-3). However, although much information about the structure of hsps and their cellular function has been accumulated, almost all these data were obtained by studying culture cells or isolated organs and tissues. Only scattered facts concern the role of hsps in providing wholebody adaptation to the close species inhabiting ecological niches with strikingly different temperature regimes (7)(8)(9)(10).Our studies focus on the heat shock response in nine lizard species that inhabit different environments and exhibit various levels ofthermoresistance. We found a direct correlation between the level of thermoresistance of a species and both the quantity of hsps belonging to the hsp70 family and the correspondent mRNA in the cells at normal physiological temperature. MAT...

In response to heat shock or other metabolic insults, an increased expression of different heat shock proteins (hsps) and, in particular, members of the hsp7O family is observed in human cells. Using two-dimensional electrophoresis, we compared the pattern of hsp7O synthesis in human fibroblast cell lines isolated from two contrasting groups of individuals. The first group was represented by native Turkmen living in the hot desert of Middle Asia; the second group consisted of Russians living in moderate climatic regions of European Russia. This analysis has shown that fibroblasts isolated from Turkmen after severe heat shock exhibited intensive synthesis of all hsps in parallel with synthesis of many other cellular proteins, while only trace synthesis of hsps was observed in the second group (Russians). Surprisingly, Northern analysis of RNA synthesis failed to reveal any differences between the two groups after heat shock treatment. When survival of fibroblasts after severe heat shock treatment was assessed by colony formation assay, the cells of the first group exhibited significantly higher survival rates.All organisms studied to date respond to an elevation of 5°C or more above their normal physiological temperature with the rapid synthesis of a highly conserved group of proteins [heat shock proteins (hsps)]. It is a widely held assumption that the purpose of the heat shock response is to protect organisms from the toxic effects of heat and other forms of stress (1, 2). hsps and, in particular, members of the hsp70 family have been implicated as essential components of protein maturation and transport (3, 4). These proteins have been shown to participate as molecular chaperones, facilitating the early events of protein synthesis, protein folding, and perhaps higher-ordered protein assembly (5,6 MATERIALS AND METHODSTissue Culture Cells of Different Origin. Diploid skin fibroblasts of two different human groups were used in the investigation. The first group was represented by Turkmen aborigines, a tribe with a certain level of inbreeding inhabiting for many generations (about 2500 years) the extremely hot and dry deserts of Middle Asia. The second group consists of Russians living in moderate climatic regions of European parts of the former U.S.S.R. Fibroblast cultures from 7-10 volunteers were compared in both groups.Heat Shock and Protein Purification. Fibroblasts used in all experiments were maintained at 37°C for 10-15 passages. The cells were cultured in Eagle's medium supplemented with 5% fetal calf serum and 5% fetal bovine serum. Each individual culture was subdivided into four flasks and heat shocked at 42.5°C in a circulating water bath for 2, 4, and 6 h. The fourth flask (control) was kept at 37°C in parallel with cells undergoing heat shock treatment, and the control cells were harvested at the end of the heat shock experiment. After heat shock, the cells were rinsed with balanced Hanks' salt medium and labeled for 1 h at 37°C in the same salt solution containing 14C-labeled amino acids ...

We compare the properties and activation of heat-shock transcription factor (HSF1) and the synthesis of a major family of heat-shock proteins (HSP70) in lizard species inhabiting ecological niches with strikingly different thermal parameters. Under normal non-heat-shock conditions, all desert-dwelling lizard species studied so far differ from a northern, non-desert species (Lacerta vivipara) in the electrophoretic mobility and content of proteins constitutively bound to the regulatory heat-shock elements in the heat-shock gene promoter. Under these conditions, levels of activated HSF1 and of both HSP70 mRNA and protein are higher in the desert species than in the non-desert species. Upon heat shock, HSF1 aggregates in all species studied, although in desert species HSF1 subsequently disaggregates more rapidly. Cells of the northern species have a lower thermal threshold for HSP expression than those of the desert species, which correlates with the relatively low constitutive level of HSPs and high basal content of HSF1 in their cells.

We demonstrated that in the desert lizard Phrynocephalus interscapularis constitutive synthesis of both members of the hsp70 family of heat shock proteins takes place in summer. Elevation of environmental and body temperatures during the day was accompanied by a pronounced (2.0-2.5 times) increase in hsp70 synthesis. Synthesis of hsps continues during the day and drops to a basal level at night. Northern hybridization analysis demonstrated a higher content of hsp-coding RNA in the cells of P. interscapularis under normal physiological conditions in comparison with the lizard Lacerta vivipara, which inhabits regions with moderate climates.

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