Correlations between salinity-persistence of ciliate species and their constitutive heat shock protein of 70 kDa contents

Our own studies of alterations in the level of constitutive heat shock protein of 70 kDa family (Hsp70) in freshwater (Paramecium jenningsi), meta-freshwater (Tetrahymena pyriformis) and curyhaline (P. nephridiatum) ciliates acclimated to salt-water and fresh-water medium were reviewed. It has been shown that the level of constitutive Hsp70 content correlates with the salinity-resistance of ciliate species: in P. jenning i it was lower in freshwater, than in marine water, in euryhaline P. nephridiatum it was higher in freshwater, than in marine water, and was more or less stable in T. pyriformis, the ciliate that occupies intermediate position between two mentioned above species according its salinity-resistance. The ecological importance of constitutive heat shock protein level is discussed in the context of salinity adaptations studies.     

Heat shock protein of Hsp70 in Paramecium nephridiatum and its role in adaptation to environmental salinity changes

The level of Hsp70 was studied in the cells of eurihaline ciliate Paramecium nephridiatum after the environmental salinity changes. Two types of treatment were applied. "Shock": ciliates were placed for 1 h to the medium with stress salinity, then transferred back to the medium, they were acclimated to, for 2 h; "adaptation": ciliates were placed for 3 h into stress salinity. It has been shown, that ciliates, acclimated to fresh water (0%) have the higher constitutive level of Hsp70, than those, acclimated to 10%. Transfer from fresh water to 10% does not cause the increase of Hsp70 synthesis in protists, whereas the reciprocal transfer results in induction of Hsp70 in the cells. "Adaptation" results in induction of Hsp70 in both "directions" of salinity changes. The results obtained allow to presume that the possibility to survive in the media of various salinity in eurihaline ciliates is somehow determined by the higher initial level of Hsp70 in their cells, than in stenohaline representatives of the same genus.     

Alterations of the level of 70 kDa family heat shock protein in the ciliate Tetrahymena pyriformis in the process of the cells adaptation to the medium salinity changes

Alterations of Hsp70 level were studied in the cells of freshwater ciliate Tetrahymena pyriformis after medium salinity changes. It is shown that ciliates, acclimated to fresh water (0 per thousand) and to salt water of 2 and 10 per thousand have similar constitutive levels of Hsp70 in their cells. Neither pronounced induction of Hsp70, was not decrease of its level, revealed in ciliates after salinity stresses. These data differ from the results obtained while studying euryhaline ciliate Paramecium nephridiatum and strongly freshwater one Paramecium jenningsi. We presume that the differences in the mode of chaperone system reaction of these ciliates species might be connected with different extents of salinity persistence - the least in P. jenningsi, intermediate in T. pyriformis and the most pronounced in P. nephridiatum.     

The Karyotype of <Emphasis Type="Italic">Amoeba borokensis</Emphasis> from a “<Emphasis Type="Italic">proteus</Emphasis>-like” Amoeba Group (Amoebozoa: Euamoebida)

The karyotype of Amoeba borokensis was studied for the first time. At the metaphase of mitosis, this species has a haploid set of chromosomes (n = 27). This is exactly half of the diploid karyotype in Amoeba proteus (strain B). At first glance, it confirms the idea that has recently appeared that one species arises from another via multiple changes in chromosome number. However, comparative cytogenetic analysis revealed that four orthologous chromosomes from haploid sets of these two species were not distinguished by the pattern of DAPI-stained bands. It shows that the genetic distance between A. proteus and A. borokensis is higher than was believed earlier and these two species have diverged from each other. Analysis of data on the life cycles of A. proteus and A. borokensis shows that a kind of so-called “cyclic polyploidy” takes place in “proteus-like” amoebae. “Cyclic polyploidy” has recently been considered as an alternative to the sexual process for genetic recombination in agamic protists from different macrotaxons.     

Changes in the 70 kDa stress protein content in the course of the <Emphasis Type="Italic">Mytilus edulis</Emphasis> L. mollusk acclimation to low salinity

The dynamics of changes in the stress protein content in the gill epithelium cells of the bivalve Mytilus edulis in the course of phenotypic adaptation to changes in environmental salinity was studied. It was demonstrated that, at low seawater salinity (10‰), which provokes the isolation reflex, induction of the Hsp70 family stress protein expression is achieved on the fifth day. The results of parallel measurements of the mussel extravisceral liquid osmolarity showed that the factor triggering stress proteins expression in the mollusks under study is not the seawater salinity, but rather osmolarity of their internal environment.     

Heat shock proteins of freshwater protists and their involvement in adaptation to changes in the environmental salinity

Changes in the level of heat shock proteins (HSP) in cells of freshwater protists, amoebae Amoeba proteus and ciliates Paramecium jenningsi, in response to changes in the environmental salinity were investigated. Changes in salinity levels were considered as a stress factor. The immunoblotting method revealed a polypeptide antigen cross-reacting with antibodies against bovine HSP70 in total protein extracts of both intact cells and cells subjected to salinity stress. The same polypeptide antigen was revealed in A. proteus cells subjected to heat shock. Therefore, it may be supposed that the polypeptide revealed after salinity shock is a heat shock protein related to the vertebrate HSP70. Under the impact of stress factor, well acclimated protists mostly spend their own previously accumulated HSP70. A conclusion is made that freshwater protists, living under conditions of increased salinity, appear to be preadapted to changes in environmental factors.     

Heat shock protein of HSP70 family revealed in some contemporary freshwater Amoebae and in Acanthamoeba sp. from cysts isolated from permafrost samples

A heat shock protein of HSP70 family was revealed for the first time in trophozoites of Acanthamoeba sp. (strain Am8) excysted from cysts previously isolated from samples of permafrost aging 30,000-35,000 years. The constitutive level of this HSP, shown by immunnoblotting in unstressed trophozoites of the ancient acanthamoebae, much surpassed that in unstressed cells of the three examined species of contemporary freshwater amebae of the genus Amoeba.     

The effect of environmental salinity on the level of heat shock proteins in gill epithelium of Mytilus edilis L. mussel

The composition and the level of heat shock proteins in the gill epithelium cells of mussels Mytilus edulis L. from the White Sea under different levels of environmental salinity were studied by the method of immunoblotting. In mussels maintained under normal salinity (26%), constitutive Hsp70 and protein of about 40 kDa were revealed. After long-term (11?C14 days) acclimation to 14 and 35?? of the level Hsp70 in gill epithelium cells increased. Hsp70 induction was also observed in cells of isolated gills after salinity shock at 14% for 3 and 24 h.     

Expression of stress proteins of HSP70 family in response to cold in Myrmica ants from various geographic populations

Expression of HSP70 is induced by stress factors, including sublethal chilling. However, the role of HSP70 for overcoming the consequences of cold stress is not clear. If it is positive, the level of HSP70 expression might be higher in populations from cold climates. Using the immunoblotting technique we investigated dynamics of HSP70 expression in response to cold stress in two Myrmica species (M. rubra and M. ruginodis) from three localities of different latitudes (50, 60 and 67°N). The results showed that in the more thermophilic species Myrmica rubra, expression of HSP70 after cold stress was higher. Within both species, HSP70 expression did not show a direct relationship with latitude. The southernmost population of M. rubra and northernmost population of M. ruginodis displayed the fastest and the most intense response. However, two other populations of M. rubra were similar in timing and intensity of the response, while in M. ruginodis the intermediate population showed the slowest and weakest response. The data suggest that expression of HSP70 may play essential role for adaptation to cold only in the northernmost population of M. ruginodis