Heat shock proteins (HSP70) as biomarkers in ecotoxicological studies

The genetic basis of adaptation to copper pollution in Drosophila melanogaster

Introduction: Heavy metal pollutants can have long lasting negative impacts on ecosystem health and can shape the evolution of species. The persistent and ubiquitous nature of heavy metal pollution provides an opportunity to characterize the genetic mechanisms that contribute to metal resistance in natural populations. Methods: We examined variation in resistance to copper, a common heavy metal contaminant, using wild collections of the model organism Drosophila melanogaster. Flies were collected from multiple sites that varied in copper contamination risk. We characterized phenotypic variation in copper resistance within and among populations using bulked segregant analysis to identify regions of the genome that contribute to copper resistance. Results and Discussion: Copper resistance varied among wild populations with a clear correspondence between resistance level and historical exposure to copper. We identified 288 SNPs distributed across the genome associated with copper resistance. Many SNPs had population-specific effects, but some had consistent effects on copper resistance in all populations. Significant SNPs map to several novel candidate genes involved in refolding disrupted proteins, energy production, and mitochondrial function. We also identified one SNP with consistent effects on copper resistance in all populations near CG11825, a gene involved in copper homeostasis and copper resistance. We compared the genetic signatures of copper resistance in the wild-derived populations to genetic control of copper resistance in the Drosophila Synthetic Population Resource (DSPR) and the Drosophila Genetic Reference Panel (DGRP), two copper-naïve laboratory populations. In addition to CG11825, which was identified as a candidate gene in the wild-derived populations and previously in the DSPR, there was modest overlap of copper-associated SNPs between the wild-derived populations and laboratory populations. Thirty-one SNPs associated with copper resistance in wild-derived populations fell within regions of the genome that were associated with copper resistance in the DSPR in a prior study. Collectively, our results demonstrate that the genetic control of copper resistance is highly polygenic, and that several loci can be clearly linked to genes involved in heavy metal toxicity response. The mixture of parallel and population-specific SNPs points to a complex interplay between genetic background and the selection regime that modifies the effects of genetic variation on copper resistance.

Transcriptomic identification of key genes in Pacific oysters Crassostrea gigas responding to major abiotic and biotic stressors

Oysters are commercially important intertidal filter-feeding species. Mass mortality events of oysters often occur due to environmental stresses, such as exposure to fluctuating temperatures, salinity, and air, as well as to metal pollution and pathogen infection. Here, RNA-seq data were used to identify shared and specific responsive genes by differential gene expression analysis and weighted gene co-expression network analysis. A total of 18 up-regulated and 10 down-regulated shared responsive genes were identified corresponding to five different stressors. Total 27 stressor-specific genes for temperature, 11 for salinity, 80 for air exposure, 51 for metal pollution, and 636 for Vibrio mediterranei pathogen stress were identified in oysters. Elongin-β was identified as a crucial gene for thermal stress response. Some HSP70s were determined to be shared responsive genes while others were specific to thermal tolerance. The proteins encoded by these stress-related genes should be further investigated to characterize their physiological functions. In addition, the uncharacterized proteins and ncRNAs that were identified may be involved in species-specific stress-response and regulatory mechanisms. This study identified specific genes related to stressors relevant to oyster cultivation. These findings provide useful information for new selective breeding strategies using a data driven method.

Set of stress biomarkers as a practical tool in the assessment of multistress effect using honeybees from urban and rural areas as a model organism: a pilot study

A decrease among honey bee populations (Apis mellifera) in the traditional apiaries has been observed in recent years. In light of this negative phenomenon, urban beekeeping seems to be an appropriate alternative solution for the bee population in reducing the toxic effects of a large number of pesticides that are commonly used in agricultural ecosystems. Despite the rapid development of urban beekeeping, there is little information regarding the different aspects of the defense effectiveness of bees from the urban and rural areas. The study was aimed to show whether honey bees from these two locations differ in the level of the valuable biomarkers of stress exposure helpful in establishing which bees, from urban or rural areas, are under greater environmental pressure. For this purpose, foragers from an urban rooftop apiary and a traditional rural apiary were collected. The chosen biomarkers were measured in various tissues of bees. The activity of glutathione S-transferase and acetylcholinesterase, the level of total antioxidant capacity, heat shock protein 70 (Hsp70), and defensin were selected for the analyses. In our opinion, the Hsp70 and defensin levels seemed to be important in the indication of urban multistress factors. The higher level of heat shock proteins and defensins in tissues/organs of bees from the urban apiary-in the gut (an increase, respectively, 92% and 7.3%) and fat body (an increase, respectively, 130% and 7.8%), known as targets of environmental toxins, pointed out the urban environment as highly stressful at both the individual and colony levels. In turn, high total antioxidant capacity was measured in the guts of honey bees from rural area (an increase 107%). Such a situation suggests a different mechanism of defense and specificity of rural and urban environmental stressors and also honey bees foraging activity.

Cross talk between heat shock protein 10 and a heat shock factor identified from Marsupenaeus japonicus

Heat shock factors (HSFs) and heat shock proteins (HSPs) are crucial regulators and effectors of the heat shock response (HSR). In this study, the full-length cDNA sequences of MjHSP10 and MjHSF1 were cloned by rapid amplification of cDNA ends (RACE). The deduced MjHSP10 and MjHSF1 amino acid (aa) sequences exhibited conserved structures and the functional features of HSP10 and HSF1, respectively. The tissue distributions and mRNA expression profiles of the two genes in response to heat stress were analyzed by quantitative real-time PCR (qRT-PCR). MjHSP10 and MjHSF1 were ubiquitously expressed in various tissues. Heat stress induced a significant increase in MjHSP10 expression that tend to positively correlate with temperature. Additionally, MjHSF1 transcription was up-regulated less than MjHSP10 transcription under heat stress. MjHSF1 expression in the hepatopancreas was up-regulated under only long-term (48 h) heat stress, and MjHSF1 transcription in the gill increased under only acute (34 °C) heat stress. MjHSF1 knockdown by RNA interference (RNAi) down-regulated MjHSP10 expression. Glutathione-S-transferase (GST) pull-down assays showed an interaction between MjHSP10 and the DNA-binding domain (DBD) of MjHSF1. This study provided new insights into cross talk between HSP10 and HSF1 in Marsupenaeus japonicus.

Protective role of zinc in Spodoptera exigua larvae under 135-generational cadmium exposure

The aim of this study was to investigate whether zinc supplementation modulates cadmium toxicity in the beet armyworm Spodoptera exigua selected for 135 generations towards cadmium tolerance. To achieve this, larvae originating from three laboratory populations of S. exigua (control strain - C; cadmium-intoxicated for 135 generations strain - Cd, and control strain intoxicated with Cd for 1 generation - CCd) were additionally exposed to zinc in three concentrations (Zn1, 400 μg Zn·g^-1 dry mass of food; Zn2; 200 μg Zn·g^-1 dry mass of food; Zn3, 100 μg Zn·g^-1 dry mass of food). As the markers of toxicity, a life history traits (the duration of L4 and L5 stages), cellular (DNA damage indices) and biochemical parameters (ADP/ATP ratio and ATP and HSP70 concentrations) were chosen. The duration of larval stages of Zn supplemented larvae was prolonged, while cellular and biochemical indicators, in general, appeared to be lower in comparison to the insects from respective reference groups in each laboratory populations. Moreover, the range of the differences depended on zinc concentration in food. We can suspect that zinc supplementation contributed to the protection of S. exigua individuals against negative effects of cadmium intoxication, probably at the cost of growth rate. Significant differences in the response pattern between insects from different laboratory populations indicate that the influence of additional stress factors is dependent on the overall condition of animals and their previous adaptation to other stressors.

Cellular and Molecular Adaptation of Arabian Camel to Heat Stress

To cope with the extreme heat stress and drought of the desert, the Arabian camel (Camelus dromedarius) has developed exceptional physiological and biochemical particularities. Previous reports focused mainly on the physiological features of Arabian camel and neglected its cellular and molecular characteristics. Heat shock proteins are suggested to play a key role in the protein homeostasis and thermotolerance. Therefore, we aim by this review to elucidate the implication of camel HSPs in its physiological adaptation to heat stress and compare them with HSPs in related mammalian species. Correlation of these molecules to the adaptive mechanisms in camel is of special importance to expand our understanding of the overall camel physiology and homeostasis.

iTRAQ-based proteomics analysis reveals the deregulated proteins related to liver toxicity induced by melamine with or without cyanuric acid in mice

The administration of melamine alone or its combination with cyanuric acid was shown to have certain liver toxicity. However, the injury mechanism of melamine-related toxicity to liver remains poorly understood. In the present study, we investigated the deregulated proteins related to liver toxicity induced by melamine with or without cyanuric acid in mice using iTRAQ quantitative proteomics technique. A total of 166 proteins were significantly changed by the melamine treatment, of which, 36 proteins were up-regulated and 130 proteins were down-regulated. Whereas, 242 proteins were significantly changed by the combined treatment of melamine and cyanuric acid, of which 81 proteins were up-regulated and 161 proteins were down-regulated. The enriched analysis of GO terms and KEGG pathway on the altered proteins showed that both enriched main GO terms and KEGG pathways appear to be different between the two kinds of treatments: melamine and mixture of melamine and cyanuric acid. Based on western blotting technique, it was confirmed that the expression of three proteins: heat shock protein 70 (HSP70), protein disulphide isomerase 6 (PDIA6) and heat shock 70 kDa protein 4-like (HSPA4L) were agreement with the findings in iTRAQ-Based quantitative analysis. These identified proteins might participate in the regulation of a wide range of biological processes, such as immune and inflammatory function, unfolded proteins response in endoplasmic reticulum, DNA damage, and the apoptosis of liver cells. These results from this study provide a new way to gain insight into the mechanisms of melamine-related toxicity to liver in animals.

Atrazine or bisphenol A mediated negative modulation of mismatch repair gene, mlh1 leads to defective oogenesis and reduced female fertility in Drosophila melanogaster

The study reports the effects of an herbicide (atrazine) and a plasticizer (Bisphenol A, BPA) on the transcriptional modulation of a mismatch repair gene (mlh1) and its adverse consequences on female fertility using Drosophila as a model. Through a chemical screen, we show that exposure to atrazine or BPA significantly downregulates mlh1 and the exposed flies had reduced fertility with smaller ovaries having reduced number of mature oocytes and abnormal distribution of ovarian follicles with increased apoptosis in them. These females had increased double-strand breaks as well as reduced synaptonemal complex formation in their ovaries suggesting altered meiotic crossing over. The eggs of these females were defective in their maternal transcripts as well as proteins and consequently, after fertilization, these eggs exhibited abnormal embryonic development. Interestingly, these phenotypes parallel that of mlh1 mutants. Further, exposure of females having reduced Mlh1 levels (mlh1^e00130/CyO) to atrazine or BPA caused severe defective phenotypes at a higher proportion than normal flies. Our findings reveal the critical role of mlh1 in atrazine and BPA mediated female reproductive toxicity, and opens up a possibility of toxicants affecting female fertility by modulating the MMR genes.

Exposure of Drosophila melanogaster to Mancozeb Induces Oxidative Damage and Modulates Nrf2 and HSP70/83

Mancozeb (MZ), a manganese- and zinc-containing ethylene-bis-dithiocarbamate, is a broad-spectrum fungicide. Harmful effects of this fungicide have been reported in nontarget organisms via a not fully understood mechanism. Drosophila melanogaster has provided remarkable contributions for toxicological studies. This work was aimed at evaluating the biochemical targets and implication of oxidative stress in MZ-mediated toxicity in drosophilas. Exposure of flies for fifteen days to MZ at 5 and 10 mg/mL through the diet impaired locomotor performance and induced fly mortality. In parallel, it caused lipid peroxidation and reactive oxygen species (ROS) formation and Mn overload. MZ inhibited superoxide dismutase and inducted catalase and glutathione S-transferase activities. Nitric oxide and reduced glutathione levels were significantly decreased by MZ. Heat shock proteins (HSP70 and HSP83) and Nrf2 mRNA levels were significantly augmented in MZ-exposed flies. Our study reinforced the use of Drosophila melanogaster as a reliable model for the study of biochemical targets of pesticides, and based on our data, MZ induced oxidative damage and Mn accumulation in a concentration-dependent manner. An adaptative cellular state was inducted by the lower concentration of pesticide, possibly contributing to the slighter damage observed.

Cross tolerance in beet armyworm: long-term selection by cadmium broadens tolerance to other stressors

Long lasting exposure of animals to stressing factor may lead to the selection of population able to cope with the stressor at lower cost than unexposed individuals. The aim of this study was to assess whether 130-generational selection of a beet armyworm to cadmium in food might have induced tolerance also to other stressors. The potential tolerance was assessed by means of unspecific stress markers: HSP70 concentration, DNA damage level, and energy budget indices in L5 larval instars of beet armyworm. The animals originated from Cd-exposed and control strains exposed additionally in a short-term experiment to high/low temperature or pesticide-spinosad. The application of the additional stressors caused, in general, an increase in the levels of studied parameters, in a strain-dependent manner. The most significant increase was found in HSP70 level in the individuals from the Cd-strain exposed to various spinosad concentration. Therefore, multigenerational contact with cadmium caused several changes that enable the insect to survive under a chronic stress, preparing the organism to the contact with an additional, new stressor. This relationship may be described as a sort of cross tolerance. This may, possibly, increase the probability of population survivorship and, at the same time, decrease the efficiency of pesticide-based plant protection efforts.

Does wastewater treatment plant upgrading with activated carbon result in an improvement of fish health?

In the present study, the efficiency of a wastewater treatment plant (WWTP) upgraded with a powdered activated carbon unit for the reduction of micropollutants and the related advantages for fish health have been analyzed by means of different biomarkers, i.e. histopathological investigations, analyses of glycogen content and stress proteins, as well as by chemical analyses in different matrices. Comparative analyses were conducted prior and subsequent to the installation of the additional purification unit. Chemical analyses revealed a significant reduction of several pharmaceuticals, including diclofenac, carbamazepine and metoprolol, in samples of effluent and surface water downstream of the WWTP after its upgrade. In addition, diminished concentrations of diclofenac and PFOS were detected in tissues of analyzed fish. Histopathological investigations of fish liver, gills, and kidney revealed improved tissue integrity in fish after improved wastewater treatment. In parallel, biochemical measurements of glycogen revealed increased energy resources in fish liver and, furthermore, hsp70 levels in livers of exposed rainbow trout and in kidneys of exposed brown trout were lower after than before the WWTP upgrade. In summary, additional treatment with powdered activated carbon led to a reduction of potentially hazardous chemicals in the effluent and the adjacent river and, consequently, to an improvement of fish health in the receiving water course.

Modulation of the response to stress factors of Xerolycosa nemoralis (Lycosidae) spiders living in contaminated environments

The rapid development of industry has caused widespread pollution in the environment, which has a negative impact on living organisms. Spiders belong to the group of animals that can exist in these anthropogenically changed areas. This is probably due to the development of tolerance mechanisms in these organisms. The impact of long-term pollution on the development of the pre-adaptation to various stress factors in spiders is unknown. In this paper, we show that living in polluted areas affects the modulation of the response to other stress factors through changes in the Hsp70 level. We observed a positive reaction to heat shock in all of the experimental groups, which was expressed by an increase in Hsp70 synthesis compared to the control. The analysis of the protein level, which was a manifestation of the pre-adaptation, was dependent on the degree of pollution on the study sites, the sexes and the type of bioassay that was performed. Our results demonstrate the reaction of spiders living in contaminated areas to the presence of additional stressors. We anticipate our results will be another voice in the discussion on the use of Hsp70 as a stress biomarker in environmental biomonitoring.

Alterations in gene expression levels provide early indicators of chemical stress during Xenopus laevis embryo development: A case study with perfluorooctane sulfonate (PFOS)

In the present study, Xenopus laevis embryos were exposed to a range of perfluorooctane sulfonate (PFOS) concentrations (0, 0.5, 6, 12, 24, 48 and 96mg/L) for 96h in laboratorial conditions to establish toxicity along with possible gene expression changes. Mortality and deformities were monitored daily and head-tail length was measured at the end of the assay as an indicator of growth. At 24 and 96h post-exposure (hpe), the mRNA expression levels of the genetic markers involved in general stress responses (hsp70, hsp47, crh-a and ucn1), oxidative stress (cat.2 and sod), lipid metabolism (ppard) and apoptosis (tp53 and bax) were analyzed by RT-qPCR. Malformations were significantly higher in the embryos exposed to the highest PFOS concentration (41.8% to 56.4%) compared to controls (5.5%) at 48, 72 and 96hpe. Growth inhibition was observed in the embryos exposed to PFOS concentrations≥48mg/L. At 24 hpe, a statistically significant up-regulation of genes hsp70, hsp47, ppard, tp53 and bax in relation to controls was found. Similar responses were found for genes hsp70, hsp47, crh-a, ucn1, sod and ppard at 96 hpe. Alterations in the mRNA expression levels indicated both a stress response to PFOS exposure during X. laevis embryo development, and alterations in the regulation of oxidative stress, apoptosis, and differentiation. These molecular alterations were detected at an earlier exposure time or at lower concentrations than those producing developmental toxicity. Therefore, these sensitive warning signals could be used together with other biomarkers to supplement alternative methods (i.e. the frog embryo test) for developmental toxicity safety evaluations, and as tools in amphibian risk assessments for PFOS and its potential substitutes.

Towards multi-level biomonitoring of nematodes to assess risk of nitrogen and phosphorus pollution in Jinchuan Wetland of Northeast China

Cultivation for agricultural production often poses threats to nearby wetlands ecosystems in fertile landscapes. In this study, nematode ecological indexes were assessed through the main soil properties of the wetlands, farmlands, and edges of wetlands and farmlands in Jinchuan Wetland by the random sampling. Behavior and reproduction in Caenorhabditis elegans (C. elegans) exposed to the sampled waters were also examined. Stress proteins Hsp70 and Hsp90 were measured both in the living field samples of C. elegans and the lab-tested C. elegans. Our results suggested that disturbance to wetland ecosystems by nitrogen and phosphorus reduced nematode richness and proportions of bacterivore nematodes. Bacterivore nematode diversity and plant-parasitic ecological index were proven to be sensitive indicators of the ecological health of wetlands. Nematode Hsp70 were useful biosensors to monitor and assess the levels of nitrogen and phosphorus pollutions in wetlands. Furthermore, multi-level soil faunal assessments by canonical correspondence analysis showed that Jinchuan Wetland is threatened with non-point source pollution from nearby farmlands.

Effects of a mixture of volatile organic compounds on total DNA and gene expression of heat shock proteins in Drosophila melanogaster

The genotoxic effects of a mixture of 13 volatile organic compounds (VOCs) on total DNA profiles and the expression of heat shock proteins (HSPs) HSP26, HSP60, HSP70, and HSP83 in fruit fly tissues were examined. Drosophila melanogaster Oregon R(+), reared under controlled conditions on artificial diets, was treated with 13 VOCs commonly found in water at concentrations of 10, 20, 50, and 75 ppb for 1 and 5 days. Band changes were clearly detected in random amplified polymorphic DNA assay, especially at the 50- and 75-ppb exposure levels, for both treatment periods. In addition, there were clear differences in the band profiles of the treated and untreated flies with changes in the band intensity and the loss/appearance of bands. Although the genomic template stability (GTS) exhibited irregular changes at the first day, significant decreases in GTS were observed after 5 days of VOC application. The lowest GTS value (27.77 ± 1.96 %) was detected at the 75-ppb level after 5 days of the treatment. Quantitative real-time polymerase chain reaction analysis showed a significant increase in the relative expression of HSP26 and HSP60 after 1 and 5 days of the treatment, respectively. The expression of HSP70 increased significantly at all treatment concentrations and times. However, the greatest increase in expression level of HSP70 (4.2-fold) occurred at 20 ppb after 5 days of the treatment. HSP83 was the least affected by exposure to the VOCs. We conclude that trace levels of a mixture of VOCs can exert genotoxic effects on both total DNA and HSP levels in Drosophila.

Synergistic effects of toxic elements on heat shock proteins

Heat shock proteins show remarkable variations in their expression levels under a variety of toxic conditions. A research span expanded over five decades has revealed their molecular characterization, gene regulation, expression patterns, vast similarity in diverse groups, and broad range of functional capabilities. Their functions include protection and tolerance against cytotoxic conditions through their molecular chaperoning activity, maintaining cytoskeleton stability, and assisting in cell signaling. However, their role as biomarkers for monitoring the environmental risk assessment is controversial due to a number of conflicting, validating, and nonvalidating reports. The current knowledge regarding the interpretation of HSPs expression levels has been discussed in the present review. The candidature of heat shock proteins as biomarkers of toxicity is thus far unreliable due to synergistic effects of toxicants and other environmental factors. The adoption of heat shock proteins as "suit of biomarkers in a set of organisms" requires further investigation.

Comprehensive transcriptome study to develop molecular resources of the copepod Calanus sinicus for their potential ecological applications

Calanus sinicus Brodsky (Copepoda, Crustacea) is a dominant zooplanktonic species widely distributed in the margin seas of the Northwest Pacific Ocean. In this study, we utilized an RNA-Seq-based approach to develop molecular resources for C. sinicus. Adult samples were sequenced using the Illumina HiSeq 2000 platform. The sequencing data generated 69,751 contigs from 58.9 million filtered reads. The assembled contigs had an average length of 928.8 bp. Gene annotation allowed the identification of 43,417 unigene hits against the NCBI database. Gene ontology (GO) and KEGG pathway mapping analysis revealed various functional genes related to diverse biological functions and processes. Transcripts potentially involved in stress response and lipid metabolism were identified among these genes. Furthermore, 4,871 microsatellites and 110,137 single nucleotide polymorphisms (SNPs) were identified in the C. sinicus transcriptome sequences. SNP validation by the melting temperature (T_m)-shift method suggested that 16 primer pairs amplified target products and showed biallelic polymorphism among 30 individuals. The present work demonstrates the power of Illumina-based RNA-Seq for the rapid development of molecular resources in nonmodel species. The validated SNP set from our study is currently being utilized in an ongoing ecological analysis to support a future study of C. sinicus population genetics.

The effects of three selected endocrine disrupting chemicals on the fecundity of fruit fly, Drosophila melanogaster

Bisphenol A (BPA), 4-nonylphenol (4-NP) and 4-tert-octylphenol (4-tert-OP) are the endocrine disrupting chemicals (EDCs) that has been shown to exert both toxic and biological effects on living organisms. The present study investigated effects of environmentally relevant concentrations of BPA, 4-NP and 4-tert-OP (0.1, 1 and 10 mg/L) on the fecundity of fruit fly Drosophila melanogaster. In the all exposure groups of BPA, 4-NP and 4-tert-OP, it was found a statistically significant decrease in mean fecundity as compared to the control groups (p < 0.05).

The use of stress-70 proteins in physiology: a re-appraisal

There are few factors more important to the mechanisms of evolution than stress. The stress response has formed as a result of natural selection, improving the capacity of organisms to withstand situations that require action.The ubiquity of the cellular stress response suggests that effective mechanisms to counteract stress emerged early in the history of life, and their commonality proves how vital such mechanisms are to operative evolution. The cellular stress response (CSR) has been identified as a characteristic of cells in all three domains of life and consists of a core 44 proteins that are structurally highly conserved and that have been termed the ‘minimal stressproteome’ (MSP). Within the MSP, the most intensely researched proteins are a family of heat-shock proteins known as HSP70. Superficially, correlations between the induction of stress and HSP70 differential expression support the use of HSP70 expression as a nonspecific biomarker of stress. However, we argue that too often authors have failed to question exactly what HSP70 differential expression signifies. Herein, we argue that HSP70 up-regulation in response to stressors has been shown to be far more complex than the commonly accepted quasi-linear relationship. In addition, in many instances, the uncertain identity and function of heat-shock proteins and heat-shock cognates has led to difficulties in interpretation of reports of inducible heat-shock proteins and constitutive heat-shock cognates. We caution against the broad application of HSP70 as a biomarker of stress in isolation and conclude that the application of HSP70 as a meaningful index of stress requires a higher degree of validation than the majority of research currently undertakes.

Expression profile analysis of antioxidative stress and developmental pathway genes in the manganese-exposed intertidal copepod Tigriopus japonicus with 6K oligochip

Manganese (Mn) provides one of aquatic pollutants in marine ecosystem. Here we used a 6K oligomicroarray to identify the effect of Mn on transcriptomes in the copepod Tigriopus japonicus. A total of 5594 spots were significantly modulated on a 6K oligomicroarray with hierarchical clustering after exposure to Mn over 24h. Of them, 186 and 489 genes were significantly upregulated and downregulated, respectively. Particularly, several genes involved in stress, detoxification, and developmental functions were significantly modulated in T. japonicus exposed for 24h. In detail, Mn exposure specifically up-regulated genes that were related to intracellular stress, antioxidant, and detoxification pathways such as cytochrome P450s (CYPs), glutathione S-transferases (GSTs), and heat shock proteins (hsps), while a majority of downregulated genes was associated with developmental pathways such as cuticle protein, ecdysone receptor, and vitellogenin. These results demonstrated that Mn exposure modulated gene expression in relation to intracellular stress, leading to developmental retardation in the intertidal copepod, T. japonicus, and provide a better understanding of mechanistic molecular studies of Mn-induced cellular damage.

The influence of lead on different proteins in gill cells from the freshwater bivalve, Corbicula fluminea, from defense to repair biomarkers

The objective of this study was to evaluate the influence of lead (Pb) on regulatory proteins linked to mechanisms of animal adaptation to polluted environments (using in vivo and in vitro tests) and to validate the in vitro assay as a tool for environmental assessment. Specimens of the bivalve Corbicula fluminea were exposed to nominal concentrations of Pb 5 mg l(-1) for 96 h. Isolated gill cells were exposed to three concentrations (1, 10, and 100 μM) for 5 h. Metal toxicity was evaluated by cell viability (trypan blue exclusion). We also analyzed Na+/K+ adenosine triphosphatase (ATPase) and carbonic anhydrase activity. Additionally, the multixenobiotic-resistance (MXR) phenotype was evaluated by the accumulation of rhodamine B (RB). Immunolabeling was used to quantify the expression of P-glycoproteins (C219) and proteins involved in ion transport, water movement, and cellular repair using antibodies against Na+/K+ ATPase, aquaporin 1, and heat-shock protein 70 (Hsp70). Pb was shown to be toxic in both in vivo and in vitro tests, in which cellular viability significantly decreased by approximately 25%. Cellular viability in the in vivo assays was determined by gill cell isolation after the entire animal was exposed to Pb. We observed that Na+/K+ ATPase activity was inhibited by 70%. Also, the expression of the MXR phenotype significantly increased in our in vivo tests. A statistically significant difference was observed in the expression of all proteins in the in vitro assays, whereas only Hsp70 increased in vivo. Employing these analyses, we could validate the sensitivity of the in vitro tests and can propose our in vitro model as a possible tool for environmental assessment.

Quantitative immunodetection of metallothioneins in relation to metals concentration in spiders from variously polluted areas

Spiders inhabiting post industrial environments, such as waste heaps or ore-bearing areas, are exposed to high concentrations of metals, accumulated in the body of their prey and transferred along food chains. Therefore spiders are pressed to develop metal-neutralization strategies. Low-molecular, multifunction proteins: metallothioneins (MTs), often postulated as biomarkers of metal exposure, are known to bind metals and thus protect organisms against their toxic effects. Yet the proteins are still not well recognized in spiders. The aim of this study was to assess, by immunodetection method, ELISA, the concentration of metallothioneins in adult females of three web building spider species: Araneus diadematus (Araneidae), Agelena labyrinthica (Agelenidae) and Linyphia triangularis (Linyphiidae) from three variously polluted areas in southern Poland: Olkusz, ore-bearing post industrial site; Katowice-WeŁnowiec: post metallurgic waste heap, Pilica: the reference, rural, area. The concentration of metallothioneins has been analyzed in relation to the metal concentration in spiders body. The study gives the evidence that metallothioneins are reliably detectable by means of ELISA technique. The analysis of results obtained shows a strong species-dependence of the MTs level. Positive correlations between MTs concentration and metal body burden (mainly Zn and Pb) were found. This suggests that the proteins play an important role in the neutralization and regulation of metal ions in spiders. The same correlation indicate the possibility to consider MTs in spiders as biomarkers of metal exposure and effects. However, the species specificity as well as metal characteristics should be taken under account.

Metallothioneins and energy budget indices in cadmium and copper exposed spiders Agelena labyrinthica in relation to their developmental stage, gender and origin

The aim of our studies was to explain the role of metallothioneins (MTs) in the neutralization of excessive amounts of metals (essential: copper (Cu) and toxic: cadmium (Cd)) and to describe the energy status in metal-exposed spiders Agelena labyrinthica in relation to its developmental stage, gender and origin. Juvenile, female and male spiders were collected from three variously polluted habitats, transferred to the laboratory and exposed to the metals in their diet. Cu and Cd accumulation in the body and exuviae, bioaccumulation factor, percentage of metallothionein positive cells, MT concentration, percentage of cells with depolarized mitochondria, ATP concentration and ADP/ATP ratio were measured and calculated. Cu appeared to be regulated and its excess is eliminated via, among others, the molting process, while Cd was rather accumulated by the spiders. The level of MTs increased significantly mainly in females exposed to both metals, irrespectively of the pollution degree of their site of origin, indicating a defensive role of the proteins. In general, even if both the MT level and the energy status indices were positively correlated with Cd and Cu concentrations in the spider body, the energy status of A. labyrinthica did not seem disturbed.

A proteomic study using zebra mussels (D. polymorpha) exposed to benzo(α)pyrene: the role of gender and exposure concentrations

It has recently been established that the use of proteomics can be a useful tool in the field of ecotoxicology. Despite the fact that the mussel Dreissena polymorpha is a valuable bioindicator for freshwater ecosystems, the application of a proteomic approach with this organism has not been deeply investigated. To this end, several zebra mussel specimens were subjected to a 7-day exposure of two different concentrations (0.1 and 2 μg L⁻¹) of the model pollutant benzo[α]pyrene (B[α]P). Changes in protein expression profiles were investigated in gill cytosolic fractions from control/exposed male and female mussels using 2-DE electrophoresis. B[α]P bioaccumulation in mussel soft tissue was also assessed to validate exposure to the selected chemical. We evaluated overall changes in expression profiles for 28 proteins in exposed mussels, 16 and 12 of which were, respectively, over- and under-expressed. Surprisingly, the comparative analysis of protein data sets showed no proteins that varied commonly between the two different B[α]P concentrations. Spots of interest were manually excised and analysed by MALDI-TOF/TOF mass spectrometry. The most significant proteins that were identified as altered were related to oxidative stress, signal transduction, cellular structure and metabolism. This preliminary study indicates the feasibility of a proteomic approach with the freshwater mussel D. polymorpha and provides a starting point for similar investigations. Our results confirm the need to increase the number of invertebrate proteomic studies in order to increase the following: their representation in databases and the successful identification of their most relevant proteins. Finally, additional studies investigating the role of gender and protein modulation are warranted.

Effects of heavy metals on insect immunocompetent cells

The influence of the following heavy metals, copper (Cu), zinc (Zn), cadmium (Cd) and lead (Pb), on haemocytes of the house fly Musca domestica L. was studied under laboratory conditions. House fly larvae were exposed to low or high, semi-lethal concentrations of metals. These particular metals were selected because they are present in polluted environments in Poland. In addition, we studied expression of the stress proteins HSP70 and HSP72 in haemocytes collected from larvae that had been exposed to heavy metal. The obtained results showed changes in haemocytes morphology and phagocytotic plasticity in the experimental flies in comparison to control. The number of prohaemocytes, regarded as stem cells, increased, while granulocytes, responsible for phagocytosis, decreased. However, we have not detected any clear changes in expression of HSP70 or HSP72 in flies treated with low or high concentrations of the heavy metals.

Stress response and potential biomarkers in spinach (Spinacia oleracea L.) seedlings exposed to soil lead

Oxidative stress and biochemical responses of spinach seedlings to soil Pb stress were investigated by pot experiments. The seedlings were exposed to 0-500 mg kg(-1) extraneous Pb. After 30 days of germination, production of O(2)(-), HSP 70, HSP 60, superoxide dismutase (SOD) activities, carbonyl groups and lipid peroxidation was significantly induced by soil Pb. After 50 days, HSP 70 and HSP 60 decreased, and HSP 60 was significantly inhibited at 500 mg kg(-1). The results indicated that Pb probably induced oxidative stress and proteotoxicity to the seedlings through O(2)(-) accumulation, and that SOD, HSP 70 and HSP 60 were important defense mechanisms to alleviate the oxidative stress. It is found that O(2)(-), HSP 70 and HSP 60 were the most sensitive parameters and had the potential to act as biomarkers for early warning of soil Pb contamination. Concentrations of soil Pb, exposing time and combination of multiple parameters should be also taken into consideration when assessing soil Pb pollution by these biomarkers.

Seasonal effect on heat shock proteins in fish from Kuwait bay

Heat shock proteins (HSP70) play a significant role in adaptation to temperature and have been proposed as an indicator of cellular stress. Since the water temperature in Kuwait's marine area varies from 13 to 35 degrees C from winter to summer, HSP70 could be a valuable tool in aquaculture in Kuwait. HSP70 levels were quantified by Western blotting in liver, muscle and gill tissues of two varieties of native fish species captured during the winter and summer months from both inside and outside the highly stressed Kuwait Bay area. The HSP70 levels did not differ statistically between fish captured from the two sampling areas. The most common response in both species was higher median levels of HSP70 in winter months. This inverse relation between HSP70 levels in the fish and the water temperature may be due to either genetic adaptation in the fish to the hot climatic conditions of the region or other stressors, such as changes in pollutant levels in the surrounding water.

Histopathological and proteomic analysis of hepatic tissue from adult male zebrafish exposed to 17β-estradiol

17β-Estradiol (E2) is known to contribute significantly a large extent to the estrogenicity in aquatic system. In the present study, two-dimensional gel electrophoresis (2-DE) and mass spectrometry (MALDI-TOF-TOF MS), combined with histopathological analysis, was used to screen hepatic responses in adult male zebrafish. Eight proteins were found to be up-regulated more than 2-fold, whereas five protein spots were down-regulated more than 2-fold after 1nM E2 treatment for 14 days, which had caused histological effects in zebrafish livers. These differentially expressed proteins accounted for a variety of cellular biological processes, such as response to oxidative stress, cell surface receptor-linked signal transduction, oxidation-reduction and cellular calcium ion homeostasis. The results demonstrated that E2 comprehensively influenced a variety of cellular and biological processes in zebrafish. Moreover, the proteomic responses elicited in zebrafish allow us to better understand the underlying mechanisms of endocrine-disrupting chemicals (EDCs)-induced toxicity fully.

Hsp70 level in progeny of aging grasshoppers from variously polluted habitats and additionally exposed to zinc during diapause

The hsp70 level in the bodies of 1st instars of grasshoppers Chorthippus brunneus from unpolluted (Pilica) and polluted (Olkusz, Szopienice) sites and additionally exposed to various doses of zinc during diapause and embryonic development prior to hatching were measured by Western blotting. The main aim of our work was to assess the relationship between the age of female grasshoppers originating from variously polluted habitat and the hsp70 level in their progeny. Possible reasons for population variation in hsp70 levels were discussed. The hsp70 level in the offspring's body depended on the place of origin. The strongest expression of hsp70 was found in the bodies of larvae hatching from the eggs laid by young females from Pilica (reference site). In contrast, a low initial level of hsp70 in larvae from polluted sites, especially in young females' progeny, was observed. The application of zinc during diapause influenced the hsp70 level in grasshopper larvae; however, the direction of the changes depended on the insects' place of origin. In larvae from the reference site, and also (but to a lesser degree) from Olkusz, the increase in the hsp70 level after zinc treatment was most pronounced. Whereas in grasshoppers from Szopienice, zinc (in 100microg g(-1) dry weight of sand) did not change the hsp70 level, or (in 500microg g(-1) dry weight of sand) caused a reduction in hsp70. The differences may result from maternal effects; however, possible adaptation also cannot be excluded. To confirm this statement further studies are needed.

Heat shock protein (Hsp) gene responses of the intertidal copepod Tigriopus japonicus to environmental toxicants

The induction of heat shock proteins (Hsps) is considered as an important protective, ecophysiologically adaptive, and genetically conserved response to environmental stress in all organisms. Among the Hsps, the heat shock protein 70 (Hsp70) family members are most extensively studied for their characterization and induction in response to environmental stressors in a range of species. We studied expression of ten Hsp transcripts in response to heat treatment in an intertidal marine copepod Tigriopus japonicus and observed that expression of Hsp70 was more pronounced than other Hsps. Subsequently, cDNA and genomic sequences of T. japonicus Hsp70 (TJ-Hsp70) were worked out by molecular cloning techniques and phylogenetic relationship was analyzed. The bacterial expression of TJ-Hsp70 and its expression in response to metal and endocrine-disrupting chemical (EDC) exposures were also studied. The TJ-Hsp70 transformed bacteria showed increased thermotolerance compared to bacteria with vector only. All the trace metals (i.e. copper, silver, and zinc) caused a concentration-dependent increase in the expression of Hsp70 transcripts. Effect of EDCs on Hsp70 expression was differential. While 4-nonylphenol (NP) and 4-t-octylpheno (OP) caused downregulation, bisphenol A (BPA) caused upregulation. The promoter region of the genomic Hsp70 sequence contained putative xenobiotic response elements (XREs) indicating that TJ-Hsp70 regulation not only by temperature but also by xenobiotics. These findings suggest that in T. japonicus, Hsp70 has a conserved role of thermotolerance and its expression in response to xenobiotics exposure appears to be a protective response.

Biochemical biomarkers in algae and marine pollution: a review

Environmental pollution by organic compounds and metals became extensive as mining and industrial activities increased in the 19th century and have intensified since then. Environmental pollutants originating from diverse anthropogenic sources have been known to possess adverse values capable of degrading the ecological integrity of marine environment. The consequences of anthropogenic contamination of marine environments have been ignored or poorly characterized with the possible exception of coastal and estuarine waters close to sewage outlets. Monitoring the impact of pollutants on aquatic life forms is challenging due to the differential sensitivities of organisms to a given pollutant, and the inability to assess the long-term effects of persistent pollutants on the ecosystem as they are bio-accumulated at higher trophic levels. Marine microalgae are particularly promising indicator species for organic and inorganic pollutants since they are typically the most abundant life forms in aquatic environments and occupy the base of the food chain. We review the effects of pollutants on the cellular biochemistry of microalgae and the biochemical mechanisms that microalgae use to detoxify or modify pollutants. In addition, we evaluate the potential uses of microalgae as bioindicator species as an early sentinel in polluted sites.

A comparison of heat shock protein genes from cultured cells of the cabbage armyworm, Mamestra brassicae, in response to heavy metals

Heat shock protein (HSP) genes, hsp90, hsp70, hsc70, hsp20.7, and hsp19.7, were cloned and sequenced from cultured cells of the cabbage armyworm, Mamestra brassicae. Analyses of the cDNA sequences revealed open reading frames of 2,151, 1,914, 1,962, 540, and 465 bp in lengths, which encode proteins with calculated molecular weights of 82.5, 69.9, 71.6, 20.7, and 19.7 kDa, respectively. An increased expression was observed in all five genes after exposure to a high temperature. The induction of gene expression was not observed during a low temperature exposure, but was observed when the cells were recovered at ambient temperature. Expression of hsp90, hsp70, and hsp20.7 was induced after exposure to 2 microM of cadmium, while the minimum cadmium concentration for induction of hsp19.7 was 5 microM. The induction of hsp90 expression was somewhat masked by basal levels of expression. Only hsp20.7 expression was induced by exposure to copper. Lead did not induce expression of any of the HSP genes tested. Cadmium-induced up-regulation of hsp70 expression was lasted longer than heat-induced one. These results suggest that hsp70 could be useful to assess the cellular distress or injury induced by cadmium.

Stress responses and metal tolerance of Chlamydomonas acidophila in metal-enriched lake water and artificial medium

Chlamydomonas acidophila faces high heavy-metal concentrations in acidic mining lakes, where it is a dominant phytoplankton species. To investigate the importance of metals to C. acidophila in these lakes, we examined the response of growth, photosynthesis, cell structure, heat-shock protein (Hsp) accumulation, and metal adsorption after incubation in metal-rich lake water and artificial growth medium enriched with metals (Fe, Zn). Incubation in both metal-rich lake water and medium caused large decreases in photosystem II function (though no differences among lakes), but no decrease in growth rate (except for medium + Fe). Concentrations of small Hsps were higher in algae incubated in metal-rich lake-water than in metal-enriched medium, whereas Hsp60 and Hsp70A were either less or equally expressed. Cellular Zn and Fe contents were lower, and metals adsorbed to the cell surface were higher, in lake-water-incubated algae than in medium-grown cells. The results indicate that high Zn or Fe levels are likely not the main or only contributor to the low primary production in mining lakes, and multiple adaptations of C. acidophila (e.g., high Hsp levels, decreased metal accumulation) increase its tolerance to metals and permit survival under such adverse environmental conditions. Supposedly, the main stress factor present in the lake water is an interaction between low P and high Fe concentrations.

Microevolution and ecotoxicology of metals in invertebrates

Risk assessment of metal-contaminated habitats based on responses in the field is complicated by the evolution of local, metal-resistant ecotypes. The unpredictability of occurrence of genetically determined adaptive traits, in terms of site-specific geochemistry, a population's inferred exposure history, and in the physiology of resistance, exacerbates the problem. Micro-evolutionary events warrant the attention of ecotoxicologists because they undermine the application of the bedrock of toxicology, the dose-response curve, to in situ field assessments. Here we survey the evidence for the existence of genetically differentiated, metal-resistant, invertebrate populations; we also describe some of the molecular mechanisms underpinning the adaptations. Quantitative changes in tissue-metal partitioning, and in the molecular and cellular responses (biomarkers)to alterations in internal bioreactive metal pools, are widely accepted as indicators of toxicity and/or exposure in free-living organisms. Both can be modulated by resistance. The understanding that all genomes are intrinsicallyflexible, with subtle sequence changes in promoter regions or epigenetic adjustments conferring significant phenotypic consequences, is deemed highly relevant. Equally relevant is the systems biology insight that genes and proteins are woven into networks. We advocate that biomarker studies should work toward assimilating and exploiting these biological realities through monitoring the activities of suites of genes (transcriptomics) and their expressed products (proteomics), as well as profiling the metabolite signatures of individuals (metabolomics) and by using neutral genetic markers to genotype populations. Ecotoxicology requires robust tools that recognize the imprint of evolution on the constitution of field populations, as well as sufficient mechanistic understanding of the molecular-genetic observations to interpret them in meaningful environmental diagnostic ways.

Multiscale approach of fish responses to different types of environmental contaminations: a case study

In order to study the responses of wild fish to environmental contaminations, different sites (two references and three contaminated) were sampled across the Walloon hydrographical network (southern Belgium). The status of fish communities was characterized according to an index of biotic integrity (IBI). Furthermore, population structure, reproductive parameters and biochemical assays were performed on chub (Leuciscus cephalus) as sentinel species. The results showed impaired responses in fish sampled downstream paper mill effluents (BKME), in a polychlorinated biphenyls (PCB) contaminated site, and in a river receiving pesticides (i.e. atrazine and hexachlorocyclohexane). High level of hepatic 7-ethoxyresorufin-Odeethylase (EROD) activity were evidence of direct toxicant exposure, while population structures showed unbalanced size-frequency distributions. Moreover, in the pesticide contaminated site, a higher proportion of atretic oocytes was found in females and abnormally high plasma alkali-labile phosphorus (ALP) values were noticed in males, compared to reference sites, suggesting that chubs were exposed to estrogenic compounds. IBI scores from both sites were also lower than in reference sites. On the other hand, no particular response was found in hepatic glutathione-S-transferase (GST) activities, hepatic heat-shock protein HSP70 concentrations and plasma sex steroids (estradiol-17beta, 11-ketotestosterone and testosterone) in chubs from any sites. By using a multiparametric approach, a better understanding of response mechanisms to pollution in fish may be achieved in order to improve the ecological status of river ecosystems.

Comparative embryotoxicity and proteotoxicity of three carrier solvents to zebrafish (Danio rerio) embryos

The present study examines the effects of ethanol (ETOH), dimethyl sulfoxide (DMSO), and acetone on zebrafish embryos and the implications of the observed results on the use of these solvents to zebrafish early life stage tests. The embryos were exposed to different concentrations (0.0, 0.0001, 0.001, 0.01, 0.1, 0.05, 1, 1.5, and 2.0% v/v) of the respective solvents by diluting reagent-grade solvent with reconstituted water [DIN 38415-6-Suborganismische Testverfahren (Gruppe T) Teil 6: Giftigkeit gegenüber Fischen. Deutsches Institute für Normung e.V]. The following endpoints were investigated (mortality, hatching rate, abnormalities, heart rate, and hsp 70 induction). No effect on survival was recorded for both acetone and DMSO even up to the highest concentration. On the other hand, embryos exposed to 1.5% and 2.0% ethanol showed a significant reduction in survival rate. No developmental defects occurred with any of the solvents at the 0.1% concentration. However, starting with 1.0%, weak to very pronounced abnormalities (weak pigmentation, edema, crooked bodies, eye defect, tail defect, reduced heartbeat, and abnormal hatching) were observed depending on the solvent type and the concentration used. Ethanol has been shown to be the most embryotoxic solvent while DMSO and acetone have comparably lesser effects. Heat shock protein 70 was induced by all solvents but at different concentration ranges. DMSO has been shown to be the most potent inducer of stress proteins. Based on the study, the chemicals tested here may be used as carrier solvents in the zebrafish embryo assay at levels below 1.5, 1.5, and 1% v/v for acetone, DMSO, and ethanol, respectively. For stress protein analysis of the exposed embryos, however, the solvent levels should be below 0.1%, 0.01%, and 1.5%, respectively. Additional and separate investigations utilizing other biomarkers should be carried out to further validate the suitability of using these solvents in a typical zebrafish embryo assay.

Assessing water quality in a tropical lake using biomarkers in zebrafish embryos: developmental toxicity and stress protein responses

In order to achieve a more substantial appraisal of lake water quality, the assessment must not be based only on chemical measurements and analyses of the water itself, but even more so on the impact of existing conditions on aquatic biota. This is possible with the use of biotests or biomarkers, e.g. investigations of the developmental parameters (96-h embryotoxicity evaluate) or of the induction of heat shock proteins (proteotoxicity evaluate). To evaluate the suitability of these tests for environmental screening, fertilized zebrafish eggs were exposed to water samples collected from five sites of varying levels of stress from Laguna Lake, Philippines. Reconstituted water was used as laboratory control while water samples from a highly polluted freshwater source was used as positive control. Developmental parameters were noted and described within 48 and 96 h of exposure. Dilution experiments of the positive control were also done to further assess and compare toxicity potentials of Laguna Lake waters with those originating from a polluted freshwater. After the 96-h exposure, the levels of stress proteins (hsp 70) were determined in embryos from all exposure groups. Results showed 100% mortality in embryos exposed to undiluted positive control (PC) within only 12 h. Increasing dilution levels, however, resulted in lower mortality and lower abnormality rates. No detectable developmental differences were noted among embryos exposed to either the laboratory control or Laguna Lake waters at the end of 96 h, regardless of the source. Very high survival rates and high hatching success rates were observed in embryos exposed to lake waters as well as laboratory control, and the data did not differ significantly among the groups. Likewise, no significant malformations were noted among all developing embryos throughout the exposure period. However, the levels of heat shock proteins in the two sites located closest to Manila, the Philippine capital (Northern West Bay and Central West Bay), showed a pronounced elevation relative to the control, indicating that these stress proteins protect the embryos from the detrimental effects of pollutants in the water. Based on the 96-h early life stage (ELS) test, the water quality of the lake is good for fishery propagation despite the current levels of pollutants in the water. This finding is in accordance with the Class C status (i.e. suitable for fish growth and propagation) as given to the lake by the local environmental agency. On the other hand, data on proteotoxicity showed that the fish are under stress, presumably deriving from pollutants. This calls for a continuous monitoring and improvement of the lake water. The present study indicates that the two biomarker methods are very easy to use, practical, rapid, and sensitive for assessing water quality in a tropical lake and recommends for their incorporation into the future monitoring program of Laguna Lake.

Expression of cytoprotective proteins, heat shock protein 70 and metallothioneins, in tissues of Ostrea edulis exposed to heat and heavy metals

Heat shock proteins (Hsps) are constitutively expressed in cells and involved in protein folding, assembly, degradation, intracellular localization, etc, acting as molecular chaperones. However, their overexpression represents a ubiquitous molecular mechanism to cope with stress. Hsps are classified into families, and among them the Hsp70 family appears to be the most evolutionary preserved and distributed in animals. In this study, the expression of Hsp70 and the related messenger ribonucleic acid (mRNA) has been studied in Ostrea edulis after exposure to heat and heavy metals; moreover, levels of metallothioneins (MTs), another class of stress-induced proteins, have contemporaneously been assessed in the same animals. Thermal stress caused the expression of a 69-kDa inducible isoform in gills of O edulis but not in the digestive gland. Northern dot blot analysis confirmed that the transcription of Hsp69-mRNA occurs within 3 hours of stress recovery after oyster exposure at 32 and 35 degrees C. Hsp69-mRNA transcripts were not present in the gills of animals exposed to 38 degrees C after 3 hours of poststress recovery, but they were detected after 24 hours. The expression of the 69-kDa protein in O edulis exposed to 38 degrees C was rather low or totally absent, suggesting that the biochemical machinery at the base of the heat shock response is compromised. Together with the expected increase in MT content, the oysters exposed to Cd showed a significant enhancement of Hsp70, although there was no clear appearance of Hsp69. Interestingly, the levels of MT were significantly increased in the tissues of individuals exposed to thermal stress. Unlike oysters, heat did not provoke the expression of inducible Hsp isoforms in Mytilus galloprovincialis, Tapes philippinarum, and Scapharca inaequivalvis, although it significantly enhanced the expression of constitutive proteins of the 70-kDa family. The expression of newly synthesized Hsp70 isoforms does not seem therefore a common feature in bivalves exposed to thermal stress.

Heavy metal accumulation, heat shock protein expression and cytogenetic changes in Tetrix tenuicornis (L.) (Tetrigidae, Orthoptera) from polluted areas

The orthopteran insect Tetrix tenuicornis, collected from polluted and unpolluted areas, was used to study heavy metal accumulation and its impact on stress protein levels and on changes in the number and morphology of chromosomes in mitotic and meiotic cells. During two consecutive years, insects were collected from polluted areas of zinc-lead mine spoils near Bolesław (Poland) and from unpolluted areas near Busko and Staszów (Poland). T. tenuicornis from the polluted area showed 1.5, 4.03, 4.32 and 41.73 times higher concentrations of copper (Cu), zinc (Zn), lead (Pb) and cadmium (Cd), respectively, than insects of the same species collected from unpolluted areas. Insects exposed to heavy metals showed only small changes, and rather a decrease in the concentration of constitutive and inducible heat shock proteins Hsp70, the level of which increases under stress conditions. A cytogenetic study of T. tenuicornis revealed intra-population anomalies in chromosome number and morphology in mitotic and meiotic cells and the presence of an additional B chromosome in germinal cells. In 50% of females collected from polluted areas, mosaic oogonial mitotic chromosome sets and diploid, hypo- or hypertetraploid, tetraploid, and octoploid chromosome numbers were detected. In turn, 14.6% of males showed a heterozygous deficiency of chromatin in L2 and M3 bivalents in addition to the presence of B chromosomes.

Stress proteins (hsp70, hsp60) induced in isopods and nematodes by field exposure to metals in a gradient near Avonmouth, UK

Heat shock proteins (hsps) are potential biomarkers for monitoring environmental pollution. In this study, the use of hsps as biomarkers in field bioassays was evaluated in terrestrial invertebrates exposed to a metal gradient near Avonmouth, UK. We investigated the hsp70 response in resident and transplanted isopods of the species Oniscus asellus and Porcellio scaber and the hsp60 response in transplanted nematodes of the species Plectus acuminatus in six field sites along the metal gradient. Considerable differences were detected in the stress responses between nematodes and isopods (isopods responded in a gradient-specific manner, nematodes did not), the two isopod species and the transplanted and resident specimens of each isopod species: in the sites closest to the smelter, O. asellus residents showed high hsp70 levels while O. asellus transplanted from an unpolluted site displayed comparatively low hsp70 levels. For P. scaber, it was just the opposite. In resident isopod populations of both species, tolerant phenotypes were revealed in the most contaminated field sites. The hsp70 level in both isopod species was a suitable biomarker of effect (but of exposure only in non-tolerant individuals) even in long-term metal-contaminated field sites. The hsp60 response in the nematode alone was not a suitable biomarker for heavily contaminated soils. However, it had indicative value when related to the hsp70 response in the isopods and could be a suitable biomarker for less heavily contaminated soils.

Heat shock gene expression and function during zebrafish embryogenesis

Recent work in the zebrafish, Danio rerio, indicates that heat shock genes are expressed in unique spatial patterns under non-stress conditions. In particular, hsp90alpha is expressed during the normal differentiation of striated muscle fibres, and hsp70-4 is expressed during normal lens development in the eye. Furthermore, disruption of the activity of either of these genes or their protein products gives rise to unique embryonic phenotypes that result from failures in proper somitic muscle development and lens development, respectively. Embryonic hsp70-4 expression is also activated in a cell-specific manner following heavy metal exposure. This has allowed for the development of a hsp70-4/eGFP reporter gene system in stable transgenic zebrafish that serves as a reliable yet extremely quick indicator of cell-specific toxicity in the context of the multicellular, living embryo.