Heat shock proteins in the mechanisms of stress adaptation in Baikal amphipods and palearctic <Emphasis Type="Italic">Gammarus lacustris</Emphasis> Sars. I. HSP70 family

The participation of HSP70 family proteins in the mechanisms of stress adaptation under thermal and toxic stress in Baikal endemic and palearctic organisms was investigated. The four Lake Baikal endemic species Gmelinoides fasciatus (Stebb.), Eulimnogammarus cyaneus (Dyb.), E. vittatus (Dyb.), Ommatogammarus fl avus (Dyb.) were compared with the palearctic fauna representative Gammarus lacustris Sars. The type of synthesis of HSP70 family heat shock proteins under thermal (exposure at a temperature of 20, 25, and 30°C) and toxic (exposure in CdCl₂ solutions with the concentrations 50, 10, 5, 0.5, and 0.05 mg/l) stress was determined. All species under investigation were shown to have a common trend towards HSP70 content increase; therewith some species-specific characteristics of the type of synthesis of the protein under investigation were observed. The conclusion has been made on HSP70 participation in the mechanisms of thermal and toxic resistance in the studied amphipod species.     

Attitude of Baikal and Palearctic amphipods to oxygen as a factor of environment and mechanism of adaptation to its lowered level

The paper presents the materials of a comparative study of characteristics of anaerobic mechanisms use under the conditions of lowered oxygen content by Baikal amphipods Eulimnogammarus vittatus (Dyb.), E. cyaneus (Dyb.), as well as by Palearctic Gammarus lacustris Sars. It is shown that the system of anaerobic metabolism works most effectively for Palearctic G. lacustris. This species is characterized by the least degree of use of low-efficient way of energy production—anaerobic lipolysis, and the highest degree of use of the most efficient way of energy production under the conditions of low oxygen content-anaerobic succinate production. For the Baikal species that are less resistant to the lowered level of oxygen we show more expressed induction of anaerobic lipolysis and lower degree of engagement of anaerobic succinate production.     

Small heat shock proteins and adaptation of various Drosophila species to hyperthermia

The dynamics and the level of accumulation of small heat shock proteins (sHSP group 21–27) after a heat exposure were studied in three Drosophila species differing in thermotolerance. The southern species Drosophila virilis, having the highest thermotolerance, surpassed thermosensitive D. lummei and D. melanogaster in the level of sHSPs throughout the temperature range tested. The results suggest an important role of sHSPs in the molecular mechanisms of adaptation to adverse environmental conditions, particularly to hyperthermia.     

Comparative analysis of the small heat shock proteins in three angiosperm genomes identifies new subfamilies and reveals diverse evolutionary patterns

The small heat shock proteins (sHSPs) are a diverse family of molecular chaperones. It is well established that these proteins are crucial components of the plant heat shock response. They also have important roles in other stress responses and in normal development. We have conducted a comparative sequence analysis of the sHSPs in three complete angiosperms genomes: Arabidopsis thaliana, Populus trichocarpa, and Oryza sativa. Our phylogenetic analysis has identified four additional plant sHSP subfamilies and thus has increased the number of plant sHSP subfamilies from 7 to 11. We have also identified a number of novel sHSP genes in each genome that lack close homologs in other genomes. Using publicly available gene expression data and predicted secondary structures, we have determined that the sHSPs in plants are far more diverse in sequence, expression profile, and in structure than had been previously known. Some of the newly identified subfamilies are not stress regulated, may not posses the highly conserved large oligomer structure, and may not even function as molecular chaperones. We found no consistent evolutionary patterns across the three species studied. For example, gene conversion was found among the sHSPs in O. sativa but not in A. thaliana or P. trichocarpa. Among the three species, P. trichocarpa had the most sHSPs. This was due to an expansion of the cytosolic I sHSPs that was not seen in the other two species. Our analysis indicates that the sHSPs are a dynamic protein family in angiosperms with unexpected levels of diversity. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Heat shock proteins and resistance to desiccation in congeneric land snails

Land snails are subject to daily and seasonal variations in temperature and in water availability and depend on a range of behavioral and physiological adaptations for coping with problems of maintaining water, ionic, and thermal balance. Heat shock proteins (HSPs) are a multigene family of proteins whose expression is induced by a variety of stress agents. We used experimental desiccation to test whether adaptation to different habitats affects HSP expression in two closely related Sphincterochila snail species, a desiccation-resistant, desert species Sphincterochila zonata, and a Mediterranean-type, desiccation-sensitive species Sphincterochila cariosa. We examined the HSP response in the foot, hepatopancreas, and kidney tissues of snails exposed to normothermic desiccation. Our findings show variations in the HSP response in both timing and magnitude between the two species. The levels of endogenous Hsp72 in S. cariosa were higher in all the examined tissues, and the induction of Hsp72, Hsp74, and Hsp90 developed earlier than in S. zonata. In contrary, the induction of sHSPs (Hsp25 and Hsp30) was more pronounced in S. zonata compared to S. cariosa. Our results suggest that land snails use HSPs as part of their survival strategy during desiccation and as important components of the aestivation mechanism in the transition from activity to dormancy. Our study underscores the distinct strategy of HSP expression in response to desiccation, namely the delayed induction of Hsp70 and Hsp90 together with enhanced induction of sHSPs in the desert-dwelling species, and suggests that evolution in harsh environments will result in selection for reduced Hsp70 expression.     

The small heat shock proteins in plants are members of an ancient family of heat induced proteins

In response to high temperature stress, plants express numerous small heat shock proteins (sHSPs) belonging to at least five related gene families. in vitro studies suggest sHSPs act as molecular chaperones to prevent irreversible heat denaturation of other proteins. The diversity of sHSPs in plants is unique among eukaryotes and makes it of interest to understand the origins of these proteins. sHSP-related proteins have now been identified in 13 prokaryotes, and in many of these prokaryotes the sHSPs are heat-regulated as seen higher plants. The prokaryotic sHSPs were analyzed by pairwise and mutliple sequence alignments with each other and with plant sHSPs. The higher plant class I cytosolic sHSPs are shown to be most similar to a subset of the prokaryotic sHSPs, including HSP 16.6 from the cyanobacterium Synechocystis. Genetic studies in this model cyanobacterium may provide insight into sHSP function in vivo, and into potential roles of sHSPs in higher plant cells.     

Small heat shock proteins from extremophiles: a review

Many microorganisms from extreme environments have been well characterized, and increasing access to genomic sequence data has recently allowed the analysis of the protein families related to stress responses. Heat shock proteins appear to be ubiquitous in extremophiles. In this review, we focus on the family of small heat shock proteins (sHSPs) from extremophiles, which are -crystallin homologues. Like the -crystallin eye lens proteins, sHSPs act as molecular chaperones and prevent aggregation of denatured proteins under heat and desiccation stress. Many putative sHSP homologues have been identified in the genomic sequences of all classes of extremophiles. Current studies of shsp gene expression have revealed mechanisms of regulation and activity distinct from other known hsp gene regulation systems. Biochemical studies on sHSPs are limited to thermophilic and hyperthermophilic organisms, and the only two available crystal structures of sHSPs from Methanocaldococcus jannaschii, a hyperthermophilic archaeon and a mesophilic eukaryote, have contributed significantly to an understanding of the mechanisms of action of sHSPs, although many aspects remain unclear.Communicated by D.A. Cowan     

Antioxidant response to natural organic matter (NOM) exposure in three Baikalean amphipod species from contrasting habitats

The aim of the present work is to comparatively evaluate the oxidative stress response on exposure to natural organic matter (NOM) in three amphipod (Crustacea, Amphipoda) species from different taxonomic groups and different habitats of Lake Baikal. Endemic species from Lake Baikal were used: the shallow-water dwelling Gmelinoides fasciatus (Dyb.), Pallasea cancelloides (Gerstf.), and the deep-layer inhabitant Ommatogammarus flavus (Dyb.). Three key enzymes, catalase (CAT), peroxidase (POD), and glutathione S-transferase (GST), were studied. The applied NOM from Lake Schwarzer (Germany) directly impacts the two littoral species which quickly respond. The response is characterized by a significant decrease of POD and an increase of CAT activities. GST activity remains stable or decreased slightly. In contrast to the littoral amphipods, the deep-layer inhabitant O. flavus showed no significant reaction to NOM exposure, probably due to decreased adaptive ability of this species. The stable environment of the Baikalean deep zones obviously does not provide triggers for the development of flexible antioxidant or general defense systems.     

Analysis of transgenic wheat (<Emphasis Type="Italic">Triticum aestivum</Emphasis> L.) harboring a maize (<Emphasis Type="Italic">Zea mays</Emphasis> L.) gene for plastid EF-Tu: segregation pattern,expression and effects of the transgene

We previously reported that transgenic wheat (Triticum aestivum L.) carrying a maize (Zea mays L.) gene (Zmeftu1) for chloroplast protein synthesis elongation factor, EF-Tu, displays reduced thermal aggregation of leaf proteins, reduced injury to photosynthetic membranes (thylakoids), and enhanced rate of CO₂ fixation following exposure to heat stress (18 h at 45°C) [Fu et al. in Plant Mol Biol 68:277–288, 2008]. In the current study, we investigated the segregation pattern and expression of the transgene Zmeftu1 and determined the grain yield of transgenic plants after exposure to a brief heat stress (18 h at 45°C). We also assessed thermal aggregation of soluble leaf proteins in transgenic plants, testing the hypothesis that increased levels of EF-Tu will lead to a non-specific protection of leaf proteins against thermal aggregation. The transgenic wheat displayed a single-gene pattern of segregation of Zmeftu1. Zmeftu1 was expressed, and the transgenic plants synthesized and accumulated three anti-EF-Tu cross-reacting polypeptides of similar molecular mass but different pI, suggesting the possibility of posttranslational modification of this protein. The transgenic plants also showed better grain yield after exposure to heat stress compared with their non-transgenic counterparts. Soluble leaf proteins of various molecular masses displayed lower thermal aggregation in transgenic than in non-transgenic wheat. The results suggest that overexpression of chloroplast EF-Tu can be beneficial to wheat tolerance to heat stress. Moreover, the results also support the hypothesis that EF-Tu contributes to heat tolerance by acting as a molecular chaperone and protecting heat-labile proteins from thermal aggregation in a non-specific manner.     

Accumulation of plant small heat-stress proteins in storage organs

Plant small heat-stress proteins (sHSPs) have been shown to be expressed not only after exposure to elevated temperatures, but also at particular developmental stages such as embryogenesis, microsporogenesis, and fruit maturation. This paper presents new data on the occurrence of sHSPs in vegetative tissues, their tissue-specific distribution, and cellular localization. We have found sHSPs in 1-year-old twigs of Acer platanoides L. and Sambucus nigra L. and in the liana Aristolochia macrophylla Lamk. exclusively in the winter months. In tendrils of Aristolochia, sHSPs were localized in vascular cambium cells. After budding, in spring, these proteins were no longer present. Furthermore, accumulation of sHSPs was demonstrated in tubers and bulbs of Allium cepa L., Amaryllis ( Hippeastrum hybridum hort.), Crocus albiflorus L., Hyacinthus orientalis L., Narcissus pseudonarcissus L., Tulipa gesneriana L., and Solanum tuberosum L. (potato). In potato tubers and bulb scales of Narcissus the stress proteins were localized in the central vacuoles of storage parenchyma cells. In order to obtain more information on a possible functional correlation between storage proteins and sHSPs, the accumulation of both types of protein in tobacco seeds during seed ripening and germination was monitored. The expression of sHSPs and globulins started simultaneously at about the 17th day after anthesis. During seed germination the sHSPs disappeared in parallel with the storage proteins. Furthermore, in embryos of transgenic tobacco plants, which do not contain any protein bodies or storage proteins, no sHSPs were found. Thus, the occurrence of sHSPs in perennial plant storage organs seems to be associated with the presence of storage proteins.     

Evolutionary Analysis of the Small Heat Shock Proteins in Five Complete Algal Genomes

Small heat shock proteins (sHSPs) are chaperones that are crucial in the heat shock response but also have important nonstress roles within the cell. sHSPs are found in all three domains of life (Bacteria, Archaea, and Eukarya). These proteins are particularly diverse within land plants and the evolutionary origin of the land plant sHSP families is still an open question. Here we describe the identification of 17 small sHSPs from the complete genome sequences of five diverse algae: Chlamydomonas reinhardtii, Cyanidioschyzon merolae, Ostreococcus lucimarinus, Ostreococcus tauri, and Thalassiosira pseudonana. Our analysis indicates that the number and diversity of algal sHSPs are not correlated with adaptation to extreme conditions. While all of the algal sHSPs identified are members of this large and important superfamily, none of these sHSPs are members of the diverse land plant sHSP families. The evolutionary relationships among the algal sHSPs and homologues from bacteria and other eukaryotes are consistent with the hypothesis that the land plant chloroplast and mitochondrion sHSPs did not originate from the endosymbionts of the chloroplast and mitochondria. In addition the evolutionary history of the sHSPs is very different from that of the HSP70s. Finally, our analysis of the algal sHSPs sequences in light of the known sHSP crystal structures and functional data suggests that the sHSPs possess considerable structural and functional diversity. Electronic supplementary material The online version of this article (doi: ) contains supplementary material, which is available to authorized users. Reviewing Editor: Dr. Rüdiger Cerff     

Possible roles of esterase, glutathione S-transferase, and superoxide dismutase activities in understanding aphid–cereal interactions

Activities of the detoxification enzymes esterase, glutathione S‐transferase, and of superoxide dismutase in aphids and aphid‐infested cereal leaves were assayed using polyacrylamide gel electrophoresis and a spectrophotometer to elucidate the enzymatic mechanisms of aphid resistance in cereal plants. A chlorosis‐eliciting Russian wheat aphid, Diuraphis noxia (Mordvilko), and non‐chlorosis‐eliciting bird cherry‐oat aphid, Rhopalosiphum padi (L.), and four cereals were used in this study. The four cereal genotypes were ‘Arapahoe’ (susceptible) and ‘Halt’ (resistant) wheat (Triticum aestivum L.), ‘Morex’ (susceptible) barley (Hordeum vulgare L.), and ‘Border’ (resistant) oat (Avena sativa L.). Esterase isozymes differed between the two aphid species, although glutathione S‐transferase and superoxide dismutase did not. Esterase, glutathione S‐transferase, and superoxide dismutase activities in either aphid species were not affected by the level of resistance of a cereal to D. noxia. The assays of cereal leaf samples showed that D. noxia feeding elicited an increase in esterase activity in all four cereal genotypes, although R. padi feeding did not. The increase of esterase activity in cereals, however, was not correlated to aphid resistance in the cereals. The time‐series assays of aphid‐infested cereal leaves showed that D. noxia‐infested Morex barley had a significant increase in esterase activity on all sampling dates (3, 6, and 9 days) in comparison with either uninfested or R. padi‐infested barley. No difference in glutathione S‐transferase activity was detected among either aphid infestations or sampling dates. The electrophoretic assays, however, revealed that aphid feeding elicited a significant increase in superoxide dismutase activity, which served as the control of glutathione S‐transferase activity assays. The increase in esterase and superoxide dismutase activities suggested that D. noxia feeding imposes not only toxic, but also oxidative stresses on the cereals. The ramification of using these enzyme activity data to understand the etiology of D. noxia‐elicited chlorosis is discussed.     

Proteome analysis on differentially expressed proteins of the fat body of two silkworm breeds, Bombyx mori, exposed to heat shock exposure

Proteomes of heat tolerant (multivoltine) and heat susceptible (bivoltine) silkworms (Bombyx mori) in response to heat shock were studied. Detected proteins from fat body were identified by using MALDI-TOF/TOF spectrometer, MS/MS, and MS analysis. Eight proteins, including small heat shock proteins (sHSPs) and HSP70, were expressed similarly in both breeds, while 4 protein spots were expressed specifically in the bivoltine breed and 12 protein spots were expressed specifically in the multivoltine breed. In the present proteomics approach, 5 separate spots of sHSP proteins (HSP19.9, HSP20.1, HSP20.4, HSP20.8, and HSP21.4) were identified. Protein spot intensity of sHSPs was lower in the multivoltine breed than in the bivoltine breed after the 45°C heat shock treatment, while the difference between two breeds was not significant after the 41°C heat shock treatment. These results indicated that some other mechanisms might be engaged in thermal tolerance of multivotine breed except for the expression of sHSP and HSP70. There were visible differences in the intensity of heat shock protein expression between male and female, however, differences were not statistically significant.     

Small heat shock protein responses in leaf tissues of wheat cultivars with different heat susceptibility

The effect of heat stress on soluble proteins extracted from leaf tissues of bread (Triticum aestivum cv. Gönen-98, tolerant; cv. Cumhuriyet-75, susceptible; genome ABD) and durum (Triticum durum cv. Ege-88, tolerant; cv. Ankara-98, susceptible; genome AB) wheat cultivars differing in sensitivity to high temperature was examined by two-dimensional gel electrophoresis. At acclimation (37°C) and acclimation→high temperature (37°C→50°C) treatments compared to control (25°C), evaluation of gels revealed 31 proteins to be differentially expressed in first leaves as a result of heat stress in heat-susceptible and heat-tolerant cultivars of bread and durum wheats. All of the increased or decreased proteins in amount, newly synthesized and/or disappeared were in low-molecular-weight (LMW, 16.1–24.0 kDa) and generally acidic character (pI 4.8–6.9). The responses of the four cultivars were compared: Twenty-two of 31 proteins were detected as newly synthesized LMW heat shock proteins (LMW HSPs = small HSPs). The number of these sHSPs was different in cultivars which have the same genome. In addition, the number of the sHSPs in heat-tolerant cultivars was higher than in heat-susceptible cultivars. Some of the sHSPs were specific to cultivar. Most of the sHSPs synthesized at 37°C were also detected at 37°C→50°C treatment. It is suggested that sHSPs have special importance in two points: Firstly, sHSPs in cultivars showed abundance and diversity. Secondly, these proteins may play an important role in the acquiring of thermal tolerance.