Acute effect of copper and cadmium exposure on the expression of heat shock protein 70 in the Cyprinidae fish Tanichthys albonubes

Reduced toxic effects of nano‑copper sulfate in comparison of bulk CuSO4 on biochemical parameters in the Rohu (Labeo rohita)

Considering the wide application of nanoparticles in various fields of life and growing concern regarding their toxic effects, the present study was designed with the aim to evaluate the potential risks of using copper sulfate nanoparticles (CuSO4-NPs) in comparison to bulk form. Nanoparticles of CuSO4, having mean size of 73 nm were prepared by ball milling method, and fingerlings of Labeo rohita were exposed to two levels, 20 and 100 μg L-1 of CuSO4 in both bulk and nano forms for 28 days and their comparative effects on the metallothioneins (MTs), heat shock proteins 70 (HSP 70), lipid profile, cholesterol (CHOL) and triglyceraldehyde (TG) levels, activities of some metabolic enzymes Alanine transaminase (ALT), Aspartate transaminase (AST) Akaline phosphatase (ALP), and genes expressions of HSP-70, TNF-α and IL1-ß were investigated. CuSO4 showed the concentration and particle type dependent effects. The over expression of HSPs and MTs, significant decreases in CHOL, TG, low density lipid (LDL) levels and ALP activity, while significant increases in high density lipid (HDL)level as well as ALT and AST activities and HSP-70, TNF-α and IL1-β expressions were observed in response to higher concentration of both bulk and nano form of copper sulfate. At lower concentration (20 μg L-1), however, only bulk form showed toxicity. Thus, low concentrations of CuSO4-NPs pose negligible threat to freshwater fish.

Effects of acute and chronic chromium stress on the expression of heat shock protein genes and activities of antioxidant enzymes in larvae of Orthetrum albistylum

The dragonfly species Orthetrum albistylum, can accumulate heavy metals from its aquatic environment and thus serves as a biological indicator for monitoring and evaluating water quality. Heat shock proteins (HSPs) play important biological roles in resistance to various types of environmental stress. The full-length cDNA sequences of the heat shock cognate (hsc) 70 and heat shock protein (hsp) 70 genes were cloned from O. albistylum larvae. Relative levels of expression of hsc70 and hsp70 in the head, epidermis, midgut, and adipose tissue were measured by qRT-PCR after chronic and acute contamination of 5-8 instar larvae with chromium (Cr) solution, and under control conditions. Activities of superoxide dismutase (SOD) and catalase (CAT) in chronically contaminated larvae were also measured. Phylogenetic analysis revealed that the cloned hsc70 and hsp70 genes were highly homologous to known HSP70 family members reported in other insects. The mRNA levels of hsc70 and hsp70 did not differ significantly in various larval tissues. Under chronic chromium stress, hsc70 and hsp70 expression were upregulated to a maximum and then downregulated; hsp70 mRNA levels were higher than those of hsc70 at all concentrations of chromium. Under acute chromium stress, hsc70 expression was inhibited at low chromium concentrations and upregulated at chromium concentrations higher than 125 mg/L. However, hsp70 expression was higher than that in the control group and markedly higher than that of hsc70. Changes in SOD and CAT activities displayed consistent trends for different chronic chromium concentrations, first increasing and then decreasing over time. Collectively, these findings demonstrated the response of the HSP family of genes and antioxidant enzymes following exposure to heavy metal stress, as well as their potential applicability as biomarkers for monitoring environmental pollutants.

Wound healing and Cadmium detoxification in the earthworm Lumbricus terrestris - a potential case for coelomocytes?

Earthworms are affected by physical stress, like injury, and by exposure to xenobiotics, such as the toxic metal cadmium (Cd), which enters the environment mainly through industry and agriculture. The stress response to the single and the combination of both stressors was examined in regenerative and unharmed tissue of Lumbricus terrestris to reveal if the stress response to a natural insult like injury (amputation) interferes with Cd detoxification mechanisms. We characterized the roles of metallothionein 1 (MT1) and MT2 isoforms, heat shock protein 70 as well as immune biomarkers such as the toll-like receptors (TLR) single cysteine cluster TLR and multiple cysteine cluster TLR. The role of the activated transcription factors (ATFs) ATF2, ATF7, and the cAMP responsive element binding protein as putative regulatory intersection as well as a stress-dependent change of the essential trace elements zinc and calcium was analyzed. Phosphorylated AMP activated protein kinase, the cellular energy sensor, was measured to explore the energy demand, while the energy status was determined by detecting carbohydrate and protein levels. Taken together, we were able to show that injury rather than Cd is the driving force that separates the four treatment groups - Control, Cd exposure, Injury, Cd exposure and injury. Interestingly, we found that gene expression differed regarding the tissue section that was analyzed and we hypothesize that this is due to the migration of coelomocytes, earthworm immune cells, that take over a key role in protecting the organism from a variety of environmental challenges. Surprisingly, we discovered a role for MT1 in the response to multiple stressors and an isoform-specific function for the two newly characterized TLRs. In conclusion, we gathered novel information on the relation of innate immunity, wound healing, and Cd detoxification mechanisms in earthworms.

Physiological and gene expression responses of the mussel Mytilus galloprovincialis to low pH and low dissolved oxygen

The prevalence and frequency of hypoxia events have increased worldwide over the past decade as a consequence of global climate change and coastal biological oxygen depletions. On the other hand, anthropogenic emissions of CO₂ and consequent accumulation in the sea surface result in a perturbation of the seawater carbonate system, including a decrease in pH, known as ocean acidification. While the effect of decreases in pH and dissolved oxygen (DO) concentration is better understood, their combined effects are still poorly resolved. Here, we exposed adult mussels (Mytilus galloprovincialis) to two pHs (8.27 and 7.63) and DO concentrations (7.65 and 2.75 mg L^-1) over 17 days in a full-factorial design. These levels correspond to extremes of the present natural variability and are relevant in the context of ocean acidification and hypoxia. No mortality was observed during the experiment. However, sublethal effects were observed for clearance and oxygen consumption rates, as well as total haemocytes count and haemocytes viability and gene expression in mussels exposed to the combination of low pH and low DO. Respiration and excretion rates were not significantly impacted by low pH and DO, alone or in combination. Overall, low pH alone led to a decrease in all tested physiological parameters while low DO alone led to a decline in clearance rate, haemocyte parameters and an increase in carbohydrate content. Both parameters led to up- or down-regulation of most of the selected genes. Not surprisingly, the combined effect of low pH and low DO could not be predicted by a simple arithmetic additive response at the effect level, highlighting more complex and non-linear effects.

Endocrine disruptors affect the expression of estrogen receptor genes and proteins in the white cloud mountain minnow Tanichthys albonubes (Teleostei: Cyprinidae)

The endocrine disruptor chemicals (EDCs) are ubiquitous in the environment, and it has raised wide public concern because of the dangers of EDCs for living organisms and the environment. In order to comparatively study the effects of EDCs [17-α-ethinylestradiol (EE2), Bisphenol A (BPA) and Nonylphenol (NP)] on the expression of estrogen receptors (ERs: erα, erβ1, and erβ2) at mRNA and protein level, total 520 adult Tanichthys albonubes were exposed to E2, EE2, BPA and NP with three concentrations respectively: EE2 (1, 5, 25 ng/l), NP (10, 50, 250 μg/l), BPA (100, 500, 2,500 μg/l) for 28 days, E2 (2, 20, 200 ng/l) being as the positive control. After treatment, the brain, eye, gill, heart, liver, gut, kidney, muscle, testis, and ovary were collected, following by the real-time quantitative PCR (RT-qPCR) and western blot methods to detect the expression levels of erα, erβ1, and erβ2 in T.albonubes at mRNA and protein level. Our results showed that high expression of terα (t means T.albonubes), terβ1, and terβ2 were detected in liver, while terβ1 and terβ2 mainly expressed in the liver, intestine, kidney, muscle and testis. EE2, BPA, and NP treatment all up-regulated the expression of terα, terβ1, and terβ2 in the brain, liver, and testis, but with some variations. Similar to mRNA level, both TERα and TERβ were up-regulated by all the EE2, BPA, and NP treatment with dose-dependent effect. In conclusion, the responses of ERs of T.albonubes to the EDCs present measurability and susceptibility, which make it possible for T. albonubes to be an efficient biomarker to monitor and evaluate the pollution of endocrine disrupting chemicals in water environment.

Repeated exposure of fluazinam fungicides affects gene expression profiles yet carries no costs on a nontarget pest

Fungicides are used to control pathogenic fungi of crop species, but they have also been shown to alter behavioral, life history and fitness related traits of nontarget insects. Here, we tested the fungicide effects on feeding behavior, survival and physiology of the nontarget pest insect, the Colorado potato beetle (CPB) (Leptinotarsa decemlineata). Feeding behavior was studied by a choice test of adult beetles, which were allowed to choose between a control and a fungicide (fluazinam) treated potato leaf. Larval survival was recorded after 24 and 72 h exposure to control and fungicide-treated leaves with 2 different concentrations. The adults did not show fungicide avoidance behavior. Similarly, survival of the larvae was not affected by the exposure to fungicides. Finally, to understand the effects of fungicides at the physiological level (gene expression), we tested whether the larval exposure to fungicide alter the expression of 5 metabolic pathway and stress associated genes. Highest concentration and 72-h exposure caused upregulation of 1 cytochrome P450 (CYP9Z14v2) and 1 insecticide resistance gene (Ldace1), whereas metabolic detoxification gene (Ugt1) was downregulated. At 24-h exposure, highest concentration caused downregulation of another common detoxification gene (Gs), while both exposure times to lowest concentration caused upregulation of the Hsp70 stress tolerance gene. Despite these overall effects, there was a considerable amount of variation among different families in the gene expression levels. Even though the behavioral effects of the fungicide treatments were minor, the expression level differences of the studied genes indicate changes on the metabolic detoxifications and stress-related pathways.

Investigation on Immune-Related Protein (Heat Shock Proteins and Metallothionein) Gene Expression Changes and Liver Histopathology in Cadmium-Stressed Fish

Heat shock proteins (HSP) are highly conserved in their structure and released in case of stress. Increased metallothionein (MT) synthesis is associated with increased capacity for binding heavy metals. Healthy juveniles of grass carp were exposed to sublethal dose (1.495 mg L⁻¹) of cadmium for 28 days. Simultaneously, a control group was also run to compare difference of total RNA expression levels in cadmium-treated and control groups. The cadmium levels in the tissues of treated fish recorded were 1.78 ± 0.10 mg L⁻¹, 1.60 ± 0.04 mg L⁻¹, and 2.00 ± 0.05 mg L⁻¹, respectively. Several histological alterations including edema, hemorrhage, dilated sinusoids, hypertrophy, hyperplasia, congestion of central vein, and nuclear alterations were observed in cadmium-exposed fish. Stress gene (metallothionein and heat shock proteins) mRNA transcription levels were studied by mRNA extraction and cDNA preparation by using PCR. The expression level of heat shock protein gene was higher as compared to metallothionein and beta-2-microglobulin gene after cadmium exposure. This study reports various stress-related immune-responsive changes of immune proteins, heat shock proteins, metallothionein, and histopathological changes in fish due to cadmium toxicity that make the fish immunocompromised which may be considered as the biomarkers of cadmium toxicity in other experimental species.

Toxic Effects on Oxidative Stress, Neurotoxicity, Stress, and Immune Responses in Juvenile Olive Flounder, Paralichthys olivaceus, Exposed to Waterborne Hexavalent Chromium

Simple Summary

Metals such as chromium can be exposed at high levels in the marine environment, and exposure to these heavy metals can have a direct effect on marine organisms. High levels of chromium exposure can have a direct impact on organisms in a coastal cage and terrestrial aquaculture. Hexavalent chromium exposure of more than 1.0 and 2.0 mg Cr⁶⁺/L induced physiological responses such as antioxidant, neurotransmitter, immune, and stress indicators in Paralichthys olivaceus. Therefore, this study will provide a reference indicator for stable aquaculture production through reference indicators for toxicity due to chromium exposure that may exist in the marine environment.

Abstract

Juvenile Paralichthys olivaceus were exposed to waterborne hexavalent chromium at various concentrations (0, 0.5, 1.0, and 2.0 mg/L) for 10 days. After chromium exposure, the activities of superoxide dismutase and glutathione S-transferase, which are oxidative stress indicators, were significantly increased; however, the glutathione level was significantly reduced. Acetylcholinesterase activity as a neurotoxicity marker was significantly inhibited upon chromium exposure. Other stress indicators, including plasma cortisol and heat shock protein 70, were significantly increased. The immune response markers (lysozyme and immunoglobulin M) were significantly decreased after chromium exposure. These results suggest that exposure to environmental toxicity in the form of waterborne chromium at concentrations higher than 1.0 mg/L causes significant alterations in antioxidant responses, neurotransmitters, stress, and immune responses in juvenile olive flounders. This study will provide a basis for an accurate assessment of the toxic effects of hexavalent chromium on aquatic organisms.

Copper exposure improves the upper thermal tolerance in a sex-specific manner, irrespective of fish thermal history

Ectotherms can respond to climate change via evolutionary adaptation, usually resulting in an increase of their upper thermal tolerance. But whether such adaptation influences the phenotypic plasticity of thermal tolerance when encountering further environmental stressors is not clear yet. This is crucial to understand because organisms experience multiple stressors, besides warming climate, in their natural environment and pollution is one of those. Here, we studied the phenotypic plasticity of thermal tolerance in three-spined stickleback populations inhabiting spatially replicated thermally polluted and pristine areas before and after exposing them to a sublethal concentration of copper for one week. We found that the upper thermal tolerance and its phenotypic plasticity after copper exposure did not depend on the thermal history of fish, suggesting that five decades of thermal pollution did not result in evolutionary adaptation to thermal tolerance. The upper thermal tolerance of fish was, on the other hand, increased by ∼ 1.5 °C after 1-week copper exposure in a sex-specific manner, with males having higher plasticity. To our knowledge this is the first study that shows an improvement of the upper thermal tolerance as a result of metal exposure. The results suggest that three-spined sticklebacks are having high plasticity and they are capable of surviving in a multiple-stressor scenario in the wild and that male sticklebacks seem more resilient to fluctuating environmental conditions than female.

Toxic effects of waterborne cadmium exposure on hematological parameters, oxidative stress, neurotoxicity, and heat shock protein 70 in juvenile olive flounder, Paralichthysolivaceus

Cadmium-induced toxicity can affect fish embryo development, ion homeostasis regulation, energy metabolism, maturation and growth, stress response, and immunity. However, studies on the toxic effects of cadmium exposure to aquatic animals, particularly olive flounder (Paralichthys olivaceus), are limited. In this study, juvenile P. olivaceus (mean length, 12.9 ± 1.3 cm; mean weight, 23.1 ± 3.2 g) was exposed to waterborne cadmium (0, 50, 100, 200, and 400 μg/L) for 10 d. Hematological parameters, including hematocrit value and hemoglobin level, in P. olivaceus were significantly decreased after waterborne cadmium exposure. Plasma components such as calcium, glucose, cholesterol, glutamic-oxaloacetic transaminase, and glutamic-pyruvic transaminase were significantly altered via cadmium exposure. The activities of antioxidant enzymes, such as superoxide dismutase, catalase, and glutathione S-transferase, were significantly altered in P. olivaceus after cadmium exposure. Acetylcholinesterase activity was significantly inhibited upon waterborne cadmium exposure. Hepatic heat shock protein 70 was significantly upregulated in P. olivaceus after waterborne cadmium exposure. Therefore, waterborne cadmium at concentrations of >100 or 200 μg/L can induce physiological toxicity in P. olivaceus via changes in hematological parameters, antioxidant enzymes, neurotransmitters, and stress indicators.

Ecotoxicological assessment of spent battery extract using zebrafish embryotoxicity test: A multi-biomarker approach

Water environmental pollution caused by spent batteries is a nonignorable environmental issue. In this study, the early life stage of zebrafish was employed to assess the environmental risk of spent batteries after exposure to 0, 1%, 2%, 5% and 10% spent battery extract for 120 h. Our results clearly indicated that spent battery extract can significantly decrease the survival rate, hatching rate and body length and increase heart rate. Moreover, spent battery extract exposure-induced zebrafish larvae generate oxidative stress and inhibit the mRNA transcriptional levels of heat shock protein (HSP70) and metallothionein (MT) genes. These results showed that the spent batteries not only affected the survival and development performance of zebrafish at an early life stage but also caused oxidative stress and interfered with the detoxification of zebrafish. This study provided novel insight into spent battery induced toxicity in the early life stage of fish.

Heat shock protein 70 gene expression and stress response of red-spotted (Epinephelus akaara) and hybrid (E. akaara female × E. lanceolatus male) groupers to heat and cold shock exposure

The importance of the temperature tolerance of fish is increasing due to climate change caused by global warming. This study examined the expression of the heat shock protein 70 (HSP70) gene, and plasma cortisol and glucose levels, as a stress response in red-spotted and hybrid groupers during exposure to heat and cold shock. Temperature in the tank where fishes acclimated at 20℃ was gradually increased or decreased, respectively, to examine the survival rate of fish. The result showed a higher survival rate of the hybrid than that of the red-spotted grouper upon exposure to a higher temperature. To further analyze the factors associated with temperature-associated stress, fishes were collected from different temperatures which changed from 20 to 30℃ or 10℃, respectively, and then back to 20℃. The expression levels of the gene encoding heat shock protein 70 (HSP70) were analyzed by qPCR using cDNA prepared from RNA extracted from the brain. A higher level of HSP70 transcript was detected in the hybrid during heat shock exposure. Analysis of cortisol and glucose from the blood of fish collected during the acclimation periods clearly indicated that the level of cortisol was increased upon temperature shift although a slight difference in the degrees of changes timing was slightly different between red-spotted grouper and hybrid. The results showed a correlation between the level of HSP70 and survival rate upon exposure to higher temperature shock. This study provides basic information regarding whether HSP70 expression increases the survival rate of fish subjected to rapid temperature changes.

HSP70 gene expression responses to the temperature stress in pufferfish (Takifugu rubripes)

In this study, we isolated and characterized HSP70 cDNA from pufferfish (Takifugu rubripes). The 3053 bp full-length TrHSP70 sequence consisted of a 167 bp 5'-UTR (untranslated region), a 2535 bp open reading frame, and a 351 bp 3'-UTR. BLAST analysis revealed that the TrHSP70 shared high similarity with HSP70 sequences in other species. In our study, we set 3 experimental groups as H1 group (20 °C), H2 group (24 °C), and H3 group (28 °C) for checking the expression level of TrHSP70 in T. rubripes. Tissue-specific gene expression results showed that TrHSP70 had higher expression in the intestines than other tissues of the T. rubripes by RT-qPCR. In the experimental group, we found that the expression of TrHSP70 was upregulated in different tissues in the H3 group. The results show that TrHSP70 is a constitutively expressed gene, which plays an important role in maintaining normal physiological function and coping with stress.

Transcriptome Analysis of the Hepatopancreas in the Litopenaeus vannamei Responding to the Lead Stress

Lead (Pb) is one of the most hazardous pollutants and toxic heavy metal in marine environment. The molecular mechanisms of Pb toxicity in aquatic organism are not well understood. In this study, hepatopancreas transcriptome of Litopenaeus vannamei (L. vannamei) was characterized by a comparison between control and Pb exposure samples using RNA-Seq approach. Hepatopancreas morphology of L. vannamei was also assessed. The result reveals that compared with the control group, an increase in the number of B cells was observed following Pb exposure in L. vannamei. Transcriptome data showed that a total of 1593 genes were recognized to be differentially expressed including 1278 up-regulated and 315 down-regulated genes. These genes were mainly associated with energy metabolism, cell apoptosis, exogenous microbial infection, cell junction, and cell adhesion. Fifteen ribosomal protein genes (RPS3, RPS13, RPSA, RPL11, RPS2, RPL8, RPS23, RPL3, RPL5, RPS6, RPS4X, RPS18, RPL19, RPL9, RPL6) were identified as the common hubs of protein-protein interaction (PPI) networks, as well as part of modules of the PPI network. Besides ribosomal protein, we identified differential expression genes (DEGs) including GAPDH, EEF1A1, HSPA8, UBC, and EEF1G as the common hubs of PPI networks. These findings may have important implications for understanding the adverse biological effects of Pb and its toxic mechanisms, as yet not clearly defined, and provide potential biomarkers of Pb exposure in hepatopancreas of L. vannamei, which might be useful for monitoring aquatic environments and assessing the health of the marine ecosystem.

Toxic effects of waterborne ammonia exposure on hematological parameters, oxidative stress and stress indicators of juvenile hybrid grouper, Epinephelus lanceolatus ♂ × Epinephelus fuscoguttatus ♀

Juvenile hybrid grouper, Epinephelus lanceolatus ♂ × Epinephelus fuscoguttatus ♀ (mean weight: 26.5 ± 2.8 g, mean length: 11.8 ± 1.3 cm) were exposed to different, sub-lethal levels of waterborne ammonia (0, 1, 2, 4, and 8 mg NH₄⁺/L) for 2 weeks. We assessed the hematological parameters, antioxidant enzymes, and stress responses of juvenile hybrid grouper after 1 week and after 2 weeks. Hematological parameters such as hemoglobin and hematocrit levels, were significantly decreased by ammonia exposure. Plasma components such as the magnesium and total protein contents, and the glutamic oxaloacetic transaminase and glutamic pyruvic transaminase activities were significantly altered by ammonia exposure; however, no changes in the magnesium levels were detected. Antioxidant responses, such as superoxide dismutase and glutathione S-transferase activities, were also significantly affected by ammonia exposure. Stress indicator levels, i.e., plasma cholesterol and heat shock protein 70 levels, were significantly increased by ammonia exposure. The results of this study indicated that ammonia exposure has toxic effects on juvenile hybrid grouper and affects their hematological parameters, antioxidant enzymes, and stress responses.

Possible prophylactic effect of omega-3 fatty acids on cadmium-induced neurotoxicity in rats' brains

Cadmium (Cd) has long been noted to induce neurodegenerative disorders. Therefore, this study aimed to assess the toxicological impact of Cd on rat brains and evaluate the possible ameliorative impact of omega-3 fatty acids as a protective agent of nervous system. Rats were divided into four groups: group I supplemented orally with saline; group II intoxicated with CdCl₂ (5 mg/kg b.w. orally), and groups III and VI supplemented with omega-3 (100 mg/kg b.w. orally) simultaneously or before CdCl₂ administration, respectively. Cd intoxication induced biochemical and histopathological disturbances in treated rats. Omega-3 fatty acid considerably improved the Cd-associated biochemical changes, reduced the elevation of lipid peroxidation, and normalized the Cd impact on the levels of superoxide dismutase, catalase, glutathione-S-transferases, 8-hydroxydeoxyguanosine, heatshock protein70, nuclear factor-κB, and interferon-γ as well as of neuronal enzymes such as acetylecholinesterase and monoamine oxidase within the brains of treated rats. Additionally, histological findings supported the results that Cd treatment-induced neurodegenerative changes and that polyunsaturated fatty acids act as antioxidants and neuroprotective agents against Cd toxicity. Co-treatment with omega-3 fatty acid was more beneficial than pretreatment. Thus, omega-3 fatty acid should be included in diet to prevent or suppress neurodegenerative disorders caused by continuous exposure to Cd.

Negative effects of acute cadmium on stress defense, immunity, and metal homeostasis in liver of zebrafish: The protective role of environmental zinc dpre-exposure

In the study, zebrafish were exposed to 0 and 200 μg/L Zn for 8 weeks, and then both groups were transferred to water including 0, 100, and 200 μg/L Cd for 4 days, respectively. Acute Cd exposure caused negative effects on stress defense, immune, and metal transport systems by increasing lipid peroxidation, iNOS activity and mRNA levels of il-6 and inos, and decreasing Cu/Zn-SOD and HSP70 levels, and mRNA levels of sod1, cat, hsp70, p65, mtf-1, znt5, zip7, atp7a, and atp7b. Lipid peroxidation was significantly reduced by Zn pre-exposure under Cd exposure, which may be explained by the enhanced stress defense capacity and the weaken inflammatory response. Firstly, Zn pre-exposure increased MTs and HSP70 levels and CAT activity in Cd-free water, which may facilitate fish quick response to Cd. Secondly, Zn pre-exposure reduced Cd accumulation at 100 and 200 μg/L Cd, down-regulated il-6 and il-1β at 100 μg/L Cd and p65 at 200 μg/L Cd, and increased Cu/Zn-SOD and CAT activities at 200 μg/L Cd. Thirdly, Zn pre-exposure alone up-regulated transcription factors (hsf1, hsf2, and mtf-1, and nrf2) and their target genes (sod1, cat, hsp70, and mt2) under Cd exposure in a dose-dependent manner. It should be noted that Zn pre-exposure down-regulated several metal transport genes dramatically at 0 and 100 μg/L Cd, which may be an important mechanism for reducing Cd import into livers. Overall, long-term and environmental Zn pre-exposure mitigated Cd toxicity by the enhanced stress defense capacity and the down-regulated metal transport and inflammatory responses.

Weak magnetic fields alter stem cell-mediated growth

Biological systems are constantly exposed to electromagnetic fields (EMFs) in the form of natural geomagnetic fields and EMFs emitted from technology. While strong magnetic fields are known to change chemical reaction rates and free radical concentrations, the debate remains about whether static weak magnetic fields (WMFs; <1 mT) also produce biological effects. Using the planarian regeneration model, we show that WMFs altered stem cell proliferation and subsequent differentiation via changes in reactive oxygen species (ROS) accumulation and downstream heat shock protein 70 (Hsp70) expression. These data reveal that on the basis of field strength, WMF exposure can increase or decrease new tissue formation in vivo, suggesting WMFs as a potential therapeutic tool to manipulate mitotic activity.

Neuroprotective effects of dietary borax in the brain tissue of rainbow trout (Oncorhynchus mykiss) exposed to copper-induced toxicity

We aimed to investigate the modulating effects of dietary borax on the pathways in rainbow trout brain exposed to copper. For this aim, a comprehensive assessment was performed including biochemical (acetylcholinesterase (AChE), malondialdehyde (MDA), oxidative DNA damage (8-hydroxy-2'-deoxyguanosine (8-OHdG), and caspase-3 levels) and transcriptional parameters (heat shock protein 70 (HSP70) and cytochromes P450 (CYP1A), glutathione peroxidase (gpx), superoxide dismutase (sod), and catalase (cat)) parameters and immunohistochemically staining of 8-OHdG. Special fish feed diets were prepared for the trial. These diets contained different concentrations of borax (1.25, 2.5, and 5 mg/kg) and/or copper (500 and 1000 mg/kg) at the period of pre- and co-treatment strategies for 21 days. At the end of the treatment periods, brain tissue was sampled for each experimental group. As a result, the biochemical parameters were increased and AChE activity decreased in the copper and copper-combined groups in comparison with the control group and also with only borax applications (p < 0.05). We observed an increase or decrease in particular biochemical parameters for the borax group in every application and we established that borax had protective effect against copper toxicity by decreasing and/or increasing the relevant biochemical parameters in brain tissue of fish. The biochemical results of borax and its combinations corresponded to the observations of gene expression data, which similarly concluded that HSP70 and CYP1A genes were strongly induced by copper (p < 0.05). In addition, the expression levels of the sod, cat, and gpx genes in the fish brains exposed to borax and the borax combination groups were significantly higher than the only copper-treated groups. In conclusion, borax supplementation provided significant protection against copper-induced neurotoxicity in trout.

HSP70 expression in Biomphalaria glabrata snails exposed to cadmium

In this study, the effects of the heavy metal cadmium on the stress protein HSP70 are investigated in freshwater mollusks Biomphalaria glabrata. Adult snails were exposed for 96h to CdCl₂ at concentrations ranging from 0.09 to 0.7mgL^-1 (LC_50/96h=0.34 (0.30-0.37). Time and concentration-dependent increases in the expression of HSP70 were observed at sub-lethal levels in the immunoblotting assay. Further, an increased survival to a lethal heat shock was observed in animals pre-exposed to a nonlethal concentration of cadmium, evidencing the induction of acquired tolerance. The present study demonstrated the inducibility of B. glabrata HSP70 by cadmium, a relevant environmental contaminant, at non-lethal levels, providing evidences that the assessment of HSP70 in B. glabrata can be regarded as a suitable biomarker for ecotoxicological studies.

Differences in structure and changes in gene regulation of murrel molecular chaperone HSP family during epizootic ulcerative syndrome (EUS) infection

Heat shock proteins (HSPs) are immunogenic, ubiquitous class of molecular chaperones, which are induced in response to various environmental and microbial stressful conditions. It plays a vital role in maintaining cellular protein homeostasis in eukaryotic cells. In this study, we described a comprehensive comparative data by bioinformatics approach on three different full length cDNA sequences of HSP family at molecular level. The cDNA sequences of three HSPs were identified from constructed cDNA library of Channa striatus and named as CsCPN60, CsHSP60 and CsHSP70. We have conducted various physicochemical study, which showed that CsHSP70 (666 amino acid) possessed a larger polypeptides followed by CsCPN60 (575) and CsCPN60 (542). Three dimensional structural analysis of these HSPs showed maximum residues in α-helices and least in β-sheets; also CsHSP60 lacks β-sheet and formed helix-turn-helix structure. Further analysis indicated that each HSP carried distinct domains and gene specific signature motif, which showed that each HSP are structurally diverse. Homology and phylogenetic study showed that the sequences taken for analysis shared maximum identity with fish HSP family. Tissue specific mRNA expression analysis revealed that all the HSPs showed maximum expression in one of the major immune organ such as CsCPN60 in kidney, CsHSP60 in spleen and CsHSP70 in head kidney. To understand the function of HSPs in murrel immune system, the elevation in mRNA expression level was analyzed against microbial oxidative stressors such as fungal (Aphanomyces invadans) and bacterial (Aeromonas hydrophila). It is interesting to note that all the HSP showed a different expression pattern and reached maximum up-regulation at 48 h post-infection (p.i) during fungal stress, whereas in bacterial stress only CsCPN60 showed maximum up-regulation at 48 h p.i, but CsHSP60 and CsHSP70 showed maximum up-regulation at 24 h p.i. The differential expression pattern showed that each HSP is diverse in function. Overall, the elevation in expression levels showed that HSPs might have potential involvement in murrel immune protection thus, protecting the organism against various external stimuli including environmental and microbial stress.

Gene Expression Profiling in Fish Toxicology: A Review

In this review, we present an overview of transcriptomic responses to chemical exposures in a variety of fish species. We have discussed the use of several molecular approaches such as northern blotting, differential display reverse transcription-polymerase chain reaction (DDRT-PCR), suppression subtractive hybridization (SSH), real time quantitative PCR (RT-qPCR), microarrays, and next-generation sequencing (NGS) for measuring gene expression. These techniques have been mainly used to measure the toxic effects of single compounds or simple mixtures in laboratory conditions. In addition, only few studies have been conducted to examine the biological significance of differentially expressed gene sets following chemical exposure. Therefore, future studies should focus more under field conditions using a multidisciplinary approach (genomics, proteomics and metabolomics) to understand the synergetic effects of multiple environmental stressors and to determine the functional significance of differentially expressed genes. Nevertheless, recent developments in NGS technologies and decreasing costs of sequencing holds the promise to uncover the complexity of anthropogenic impacts and biological effects in wild fish populations.

Immunotoxicological effects of cadmium on Labeo rohita, with emphasis on the expression of HSP genes

The present study evaluated the effects of exposure (28 days) to a sub-lethal concentration of cadmium (Cd) (0.65 mg CdCl2 L(-1)) on the immune responses and expression of immune-related and heat shock protein (HSP) genes in Labeo rohita, an important aquacultured fish species. Among the immune parameters studied, significantly lower lysozyme activity was observed in fish 28 days post-exposure (dpe) to Cd as compared to control fish. Alternative complement pathway activity was slightly higher in the Cd-exposed group at 2 dpe than in controls, and this activity declined gradually thereafter. The phagocytic activity and serum immunoglobulin M (IgM) levels were insignificantly lower in the Cd-exposed group at all assessed time points than in controls. Among serum enzymatic activities, peroxidase activity was always higher in the Cd-exposed group than in controls, but the increase was insignificant at all assessed time points. Additionally, serum glutamic-pyruvic transaminase and alkaline phosphatase activities were significantly higher in the Cd-exposed group at 14 and 28 dpe. Immune and HSP gene expression patterns were observed in kidney and liver tissues, respectively, by RT-PCR, and HSPs were further analysed by immunoblotting. Cd had an immunosuppressive effect, leading to down-regulation of TNF-α, IL-1β, IL-10, and IFN-γ. However, Cd exposure led to the up-regulation of HSP47, HSP60, HSP70, HSP78, and HSP90, indicating Cd-induced cellular stress. Taken together, the results of this study demonstrate the immunotoxic effect of Cd. Cd exposure makes Labeo rohita immunocompromised, and this could subsequently increase the disease susceptibility of Labeo rohita.

Characterization of Multiple Heat-Shock Protein Transcripts from Cydia pomonella: Their Response to Extreme Temperature and Insecticide Exposure

The economically important fruit pest Cydia pomonella (L.) exhibits a strong adaptability and stress tolerance to environmental stresses. Heat-shock proteins (HSPs) play key roles in insects in coping with environmental stresses. However, little is known about the spatiotemporal expression patterns of HSPs and their response to stresses in C. pomonella. In this study, a thermal treatment-recovery test was performed, and the expression profiles of a novel isolated HSP, named CpHSP40, and six CpHSPs were determined. Third-instar larvae were able to recover from cold shock (0 °C) and heat shock (40 °C). Escherichia coli BL21 (DE3) cells harboring recombinant pET-28a (+)-CpHSP40 plasmid showed significant temperature tolerance. CpHSPs were developmentally and tissue-specifically expressed. The responses of CpHSPs to 0 and 40 °C (with or without recovery) and insecticide exposure were varied. All of these indicated that the expression of HSPs plays a role in the development and in environmental adaptation in C. pomonella.

Characterization and function analysis of Hsp60 and Hsp10 under different acute stresses in black tiger shrimp, Penaeus monodon

Heat shock proteins (Hsps) are a class of highly conserved proteins produced in virtually all living organisms from bacteria to humans. Hsp60 and Hsp10, the most important mitochondrial chaperones, participate in environmental stress responses. In this study, the full-length complementary DNAs (cDNAs) of Hsp60 (PmHsp60) and Hsp10 (PmHsp10) were cloned from Penaeus monodon. Sequence analysis showed that PmHsp60 and PmHsp10 encoded polypeptides of 578 and 102 amino acids, respectively. The expression profiles of PmHsp60 and PmHsp10 were detected in the gills and hepatopancreas of the shrimps under pH challenge, osmotic stress, and heavy metal exposure, and results suggested that PmHsp60 and PmHsp10 were involved in the responses to these stimuli. ATPase and chaperone activity assay indicated that PmHsp60 could slow down protein denaturation and that Hsp60/Hsp10 may be combined to produce a chaperone complex with effective chaperone and ATPase activities. Overall, this study provides useful information to help further understand the functional mechanisms of the environmental stress responses of Hsp60 and Hsp10 in shrimp.

Effects of Single and Joint Subacute Exposure of Copper and Cadmium on Heat Shock Proteins in Common Carp (Cyprinus carpio)

Copper (Cu) and cadmium (Cd) are the most common heavy metals that are easily detected in aquatic environments on a global scale. In this paper, we investigated the messenger RNA (mRNA) and protein levels of HSPs (HSP60, HSP70, and HSP90) in the liver of the common carp exposed to Cu, Cd, and a combination of both metals by real-time quantitative PCR and Western blot. The results indicated that in each exposure group, the mRNA levels of HSP60, HSP70, and HSP90 were increased significantly compared to the corresponding controls after 96 h of exposure (P < 0.05). A significant increase was observed in the HSP70 protein level in the high-dose Cu group and all of the Cd groups. Significant increases were also observed in the protein levels of HSP60 and HSP90 in the high combination group and the low combination group, respectively. These results indicated that the dynamics of HSP expression observed in the common carp support the role of HSPs as biochemical markers in response to environmental pollution and provided valuable insights into the adaptive mechanisms used by the common carp to adapt to the challenges of stressful environments.

The Functions of Antioxidants and Heat Shock Proteins Are Altered in the Immune Organs of Selenium-Deficient Broiler Chickens

Despite increasing evidence indicating the essential involvement of selenium (Se) in the immune system, the effect of Se deficiency on the regulation of oxidative stress and heat shock proteins (Hsps) in broiler chickens is still unclear. In the present study, we established an exudative diathesis (ED) broiler chicken model caused by Se deficiency. We then analyzed histological observations and detected the expression levels of Hsps and antioxidant indexes in immune tissues. The antioxidant function declined remarkably, and most of the Hsp expression levels increased significantly in the spleen, thymus, and bursa of Fabricius of the broiler chicks with ED (except the messenger RNA (mRNA) levels of Hsp27, Hsp40, and Hsp70, which decreased in thymus tissues from the treatment groups); therefore, constitutive oxidation resistance and higher Hsps in broiler chicks with ED caused defects in immune organ morphology and function, as evidenced by abnormal histological structures: red pulp broadening and lymphocytes in the cortex and medulla of the thymic lobule decreased distinctly and distributed loosely. These results underscore the importance of Se in establishing an immune organ microenvironment conducive to normal function.

Alteration of cytochrome P450 1 regulation and HSP 70 level in brain of juvenile common carp (Cyprinus carpio) after chronic exposure to tributyltin

Tributyltin (TBT), a toxic contaminant in aquatic environments, has bio-accumulated in aquatic food webs throughout the world and can be found at toxic levels in some biota. However, the molecular mechanisms and effects of TBT are not fully understood. The aim of the present study was to investigate the effect of long-term exposure of TBT on cytochrome P450 (CYP450) 1 regulation and heat-shock proteins (HSPs) profiling in brain of freshwater teleost. The effects of long-term exposure to TBT on mRNA expression of cytochrome P450 (CYP450) 1 family genes and ethoxyresorufin O-deethylase (EROD) activity in the brain of common carp were evaluated, as well as HSP 70 level. Fish were exposed to sublethal concentrations of TBT (75 ng/L, 0.75 μg/L and 7.5 μg/L) for 15, 30, and 60 days. Based on the results, long-term exposure (more than 15 days) to TBT could lead to obvious physiological-biochemical responses (based on EROD activity, HSP 70 level and CYP450 1 family genes expression). The mRNA expression of CYP450 1 family genes (CYP1A, CYP1B, CYP1C1 and CYP1C2) suggested that CYP1A was to accommodate most EROD activity in fish, but other CYP450 forms also involved in this proceeding. Thus, the measured physiological responses in fish brain could provide useful information to better understand the mechanisms of TBT-induced bio-toxicity and could be used as potential biomarkers for monitoring the TBT pollution in the field.

Cadmium Protection Strategies--A Hidden Trade-Off?

Cadmium (Cd) is a non-essential transition metal which is introduced into the biosphere by various anthropogenic activities. Environmental pollution with Cd poses a major health risk and Cd toxicity has been extensively researched over the past decades. This review aims at changing the perspective by discussing protection mechanisms available to counteract a Cd insult. Antioxidants, induction of antioxidant enzymes, and complexation of Cd to glutathione (GSH) and metallothionein (MT) are the most potent protective measures to cope with Cd-induced oxidative stress. Furthermore, protection mechanisms include prevention of endoplasmic reticulum (ER) stress, mitophagy and metabolic stress, as well as expression of chaperones. Pre-exposure to Cd itself, or co-exposure to other metals or trace elements can improve viability under Cd exposure and cells have means to reduce Cd uptake and improve Cd removal. Finally, environmental factors have negative or positive effects on Cd toxicity. Most protection mechanisms aim at preventing cellular damage. However, this might not be possible without trade-offs like an increased risk of carcinogenesis.

Two isoforms of leptin in the White-clouds Mountain minnow (Tanichthys albonubes): Differential regulation by estrogen despite similar response to fasting

Leptin has been well-established as a canonical anorexic peptide hormone in mammals, though much of its function in fish remains obscure. In this study, the cDNAs of two leptin isoforms (leptin-A and leptin-B) were cloned from the liver of a small cyprinid fish, Tanichthys albonubes. The two T. albonubes leptins, sharing low primary amino acid sequence homology with their mammalian counterparts, and between themselves, are highly conserved in three-dimensional protein structures and gene structures. Liver is a major source of leptin mRNA in T. albonubes with leptin-A being the dominant form. The expression of hepatic leptin-A but not leptin-B mRNA in female fish is significantly higher than in male fish. Transcriptional hepatic levels of leptin-A and leptin-B in both male and female fish were demonstrated to increase after long-term fasting (10-25days) but decline upon re-feeding (3days). Strikingly, estrogen (E2) administration induced only leptin-A but not leptin-B hepatic mRNA expression in both male and female fish. Our study here provides the first evidence for differential regulation of two leptins in fish, and sheds new light on the possible origin of leptin in lower vertebrates.

The change in heat shock protein expression in avermectin induced neurotoxicity of the pigeon (Columba livia) both in vivo and in vitro

The expression of heat shock proteins (Hsps) commonly increases to provide neuroprotection when brain tissues are under stress conditions. Residues of avermectins (AVMs) have neurotoxic effects on a number of non-target organisms. The aim of this study was to investigate the effects of AVM exposure on the expression levels of Hsp 60, Hsp 70 and Hsp 90 for pigeon (Columba livia) neurons both in vivo and in vitro. The results showed that in general, the mRNA and protein levels of Hsps were increased in treated groups relative to control groups after AVM exposure for 30d, 60d and 90d in the cerebrum, cerebellum and optic lobe in vivo. However, AVM exposure had no significant effects on the transcription expression of Hsps for 90d in the optic lobe and decreased the translation expression of Hsps significantly for 90d in the optic lobe. In vitro, the LC50 of avermectin for King pigeon neurons is between 15μgL(-1) and 20μgL(-1). Following AVM (2.5-20μgL(-1)) exposure, the mRNA expression of the 3 Hsps was up-regulated to different degrees. Compared with the control groups, a significant decrease, a remarkable increase and a non-significant change was found in the protein expression of Hsp 60, Hsp 70 and Hsp 90 separately following AVM (2.5-20μgL(-1)) exposure. Based on these results, we conclude that AVM exposure can induce a protective stress response in pigeons by means of promoting the mRNA and protein expression of Hsps under in vivo and in vitro conditions, thus easing the neurotoxic effects of AVM to some extent.

Acute copper toxicity in juvenile fat snook Centropomus parallelus (Teleostei: Centropomidae) in sea water

Three experiments were designed to assess the accumulation and acute toxicity of copper (Cu) in juvenile fat snook Centropomusparallelus. The first experiment was performed to determine the 96-h lethal concentration (LC50) of Cu. The second experiment was designed to assess the effects of sublethal concentrations of Cu (0.47 and 0.94 mg/L), while the third one allowed us to test the recovery capacity of fish exposed to the sublethal concentrations Cu and kept in sea water without Cu addition. The LC50value for Cu was found to be 1.88 mg/L Cu. Fish exposed to the sublethal concentrations of Cu showed a significant accumulation of Cu in gills at 96 h respect to the control ones (0.43 µg/g Cu). No significant difference was observed in the accumulation of Cu in gills between fish exposed to 0.47 mg/L (1.09 µg/g Cu) and 0.94 mg/L (1.26 µg/g Cu). Exposure (24 and 96 h) to the sublethal concentrations of Cu tested induced DNA damage in the erythrocytes. The results show that acute exposure to sublethal concentrations induces Cu accumulation and DNA damage in fish, these effects being recovered after 240 h in sea water without Cu addition.

Effects of pathogenic bacterial challenge after acute sublethal ammonia-N exposure on heat shock protein 70 expression in Botia reevesae

The objective of this study was to investigate the effects of pathogenic bacterial challenge after acute sublethal ammonia-N exposure on heat shock protein 70 expression in Botia reevesae. After ammonia-N exposure at a constant concentration of 7.21 ± 0.10 mg L(-1) for 96 h, B. reevesae was challenged with Aeromonas hydrophila. Quantitative PCR analysis showed predominant and significant expression of HSP70 in liver, gill, skin, spleen and kidney (P < 0.05), with significantly upregulated expression of the mRNA transcript in these tissues after sublethal ammonia-N exposure and A. hydrophila challenge. Furthermore, following A. hydrophila challenge after ammonia-N exposure, HSP70 mRNA expression was significantly upregulated in kidney and gill tissues, although its expression levels were significantly lower than those detected following A. hydrophila challenge or ammonia-N exposure individually. These results indicate that B. reevesae HSP70 is involved in resistance to pathogenic bacteria. It is hypothesized that ammonia-N results in the downregulation of HSP70 mRNA in immune organs after an A. hydrophila challenge, thus lowering their resistance to pathogenic stress.