Biomarkers Of Environmental Stress Research Articles

Effects of myo-inositol on growth and biomarkers of environmental stress and metabolic regulation in Pacific white shrimp (Litopenaeus vannamei) reared at low salinity

This study explored the role of myo-inositol in alleviating the low salinity stress of White Shrimp (Litopenaeus vannamei). Juvenile shrimp (0.4 ± 0.02 g) in low salinity (salinity 3) water were fed diets with myo-inositol levels of 0, 272, 518, 1020 and 1950 mg/kg (crude protein is 36.82 %, crude lipid is 7.58 %), fed shrimp in seawater at a salinity of 25 were fed a 0 mg/kg myo-inositol diet as a control (Ctrl). The experiment was carried out in tanks (50 L) with satiety feeding, and the experiment lasted for 6 weeks. After sampling, the serum was used to measure immune function, the hepatopancreas homogenate was used to measure the antioxidant capacity and hepatopancreas damage state, the hepatopancreas was used for transcriptomics analysis, and the gills were used for qPCR to measure osmotic pressure regulation. The results showed that the final weight and survival of the shrimp in the 1020 mg/kg group increased significantly compared with those in the other low salinity groups, but the final weight and biomass increase were significantly lower than those in the Ctrl group. Dietary myo-inositol improved the antioxidant capacity of shrimp under low salinity. B-cell hyperplasia and hepatic duct damage were observed in the hepatopancreas in the 0 mg/kg group. The results of transcriptome analysis showed that myo-inositol could participate in the osmotic pressure regulation of shrimp by regulating carbohydrate metabolism, amino acid metabolism, lipid metabolism and other related genes. Myo-inositol significantly affected the expression of related genes in ion transporter and G protein-coupled receptor-mediated pathways. This study demonstrated that myo-inositol can not only act as an osmotic pressure effector and participate in the osmolar regulation of shrimp through the phosphatidylinositol signaling pathway mediated by G protein-coupled receptors but also relieve low salinity stress by mediating physiological pathways such as immunity, antioxidation, and metabolism in shrimp. The binomial regression analysis of biomass increases and survival showed that the appropriate amount of myo-inositol in the L. vannamei diet was 862.50–1275.00 mg/kg under low salinity.

Energy Status of Stygophilous Amphipod Synurella ambulans as a Promising Biomarker of Environmental Stress in the Hyporheic Zone

The hyporheic zone (HZ) is a sensitive ecotone in river ecosystems because of its biodiversity and susceptibility to human activities. Hyporheic fauna are exposed to multiple stressors that affect the physiology and metabolism of organisms and ultimately ecosystem functioning and biodiversity. This study aimed to quantify adenine nucleotides in the stygophilous freshwater amphipod Synurella ambulans and to evaluate the potential of adenylate energy charge (AEC) as a physiological biomarker of general stress in the HZ of the Sava River at sites with different intensities of environmental and anthropogenic stress. Field studies were conducted seasonally (in December 2018 and April, July, and October 2019) at two sampling sites, one upstream (1-UP) and the other downstream (2-DOWN) of the discharge from the wastewater treatment plant using the standard piston pump. The amphipod population from site 1-UP had significantly higher AEC values than the population from site 2-DOWN in all seasons except summer. Coordinated changes in AEC values with the ATP/ADP ratio indicated differences in energy status between the two populations. However, no changes in the apparent equilibrium constant of adenylate kinase were observed, except in spring at site 1-UP. Multiple linear regression models showed the strongest associations of AEC with Fe and Zn accumulated in amphipods, followed by environmental factors (conductivity, dissolved O2, and concentrations of nitrites and phosphates in the interstitial water). AEC was shown to be a useful index of environmental stress in S. ambulans because it can directly measure the change in available energy and thus the metabolic stress to which the organism is exposed. Finally, seasonal and spatial variations in AEC values reflected ecological status in the HZ.

Wings are not perfect: increased wing asymmetry in a tropical butterfly as a response to forest fragmentation.

Habitat fragmentation and ecosystem changes have the potential to affect animal populations in different ways. To effectively monitor these changes, biomonitoring tools have been developed and applied to detect changes in population structure and/or individual traits that reflect such changes. Fluctuating asymmetry (FA) represents random deviations from perfect symmetry in bilateral traits from perfect symmetry in response to genetic and/or environmental stresses. In this study, we evaluated the use of FA as a tool to monitor stress caused by forest fragmentation and edge formation, using the tropical butterfly M. helenor (Nymphalidae) as a model species. We collected adult butterflies from three fragments of Atlantic Forest in Brazil encompassing both edge and interior habitats. Four wing traits (wing length, wing width, ocelli area, and ocelli diameter) were evaluated. Butterflies captured at edge sites exhibited higher FA values for wing length and wing width compared to those captured at interior sites, whereas traits related to ocelli did not show differences between the two habitat types. Our results suggest that the differences in abiotic and biotic conditions between forest interior and edges can act as a source of stress, impacting the symmetry of flight-related traits. On the other hand, as ocelli are crucial for butterfly camouflage and counter-predator strategies, our results indicate that this trait may be more conserved. By employing FA, we identified trait-specific responses to habitat fragmentation, thus suggesting its potential as a biomarker for environmental stress that can be used in butterflies to monitor habitat quality and change.

Understanding Diversity, Evolution, and Structure of Small Heat Shock Proteins in Annelida Through in Silico Analyses

Small heat shock proteins (sHsps) are oligomeric stress proteins characterized by an α-crystallin domain (ACD). These proteins are localized in different subcellular compartments and play critical roles in the stress physiology of tissues, organs, and whole multicellular eukaryotes. They are ubiquitous proteins found in all living organisms, from bacteria to mammals, but they have never been studied in annelids. Here, a data set of 23 species spanning the annelid tree of life, including mostly transcriptomes but also two genomes, was interrogated and 228 novel putative sHsps were identified and manually curated. The analysis revealed very high protein diversity and showed that a significant number of sHsps have a particular dimeric architecture consisting of two tandemly repeated ACDs. The phylogenetic analysis distinguished three main clusters, two of them containing both monomeric sHsps, and ACDs located downstream in the dimeric sHsps, and the other one comprising the upstream ACDs from those dimeric forms. Our results support an evolutionary history of these proteins based on duplication events prior to the Spiralia split. Monomeric sHsps 76) were further divided into five subclusters. Physicochemical properties, subcellular location predictions, and sequence conservation analyses provided insights into the differentiating elements of these putative functional groups. Strikingly, three of those subclusters included sHsps with features typical of metazoans, while the other two presented characteristics resembling non-metazoan proteins. This study provides a solid background for further research on the diversity, evolution, and function in the family of the sHsps. The characterized annelid sHsps are disclosed as essential for improving our understanding of this important family of proteins and their pleotropic functions. The features and the great diversity of annelid sHsps position them as potential powerful molecular biomarkers of environmental stress for acting as prognostic tool in a diverse range of environments.

Identifying Euglena Gracilis Metabolic and Transcriptomic Adaptations in Response to Mercury Stress

Mercury contamination in aquatic systems poses a serious environmental stress to phototrophic plankton. We used Euglena gracilis to gain an understanding of the physiochemical changes resulting from mercury stress across the transcriptome and metabolome. Using a combination of Fourier Transform Ion Cyclotron Resonance Mass Spectrometry (FT-ICR-MS) and RNA-sequencing, we identified metabolomic and transcriptomic changes both within and outside cellular space after mercury exposure. Metabolic profiles of E. gracilis were less diverse after mercury exposure, highlighting an overall refinement of metabolites produced. Significant fold changes in cysteine, glutathione, and amino acid-based metabolites were significantly higher (p < 0.05) within the mercury exposed cells and in extracellular space than in untreated cultures. Using integrated omics analyses, a significant upregulation of transcripts and metabolites involved in amino acid synthesis, cellular responses to chemical stress, reactive oxygen species detoxification, and electron transport were identified. Together the enrichment of these pathways highlights mechanisms that E. gracilis harness to mitigate oxidative stress at sublethal concentrations of mercury exposure and give rise to new biomarkers of environmental stress in the widely distributed E. gracilis.

Effects of landscape disturbance on seed germination of Enterolobium contortisiliquum (Fabaceae) in Brazilian seasonally tropical dry forest: Are seeds a sensitive biomarker of environmental stress?

Habitat disturbance of native forests is currently the major threat to biodiversity conservation. Plant species can be negatively affected as a result of landscape conversion; thus, it is essential to detect the potential effects of environmental stress on plant performance using reliable bioindicators of quick, cheap diagnosis. Fluctuating asymmetry (FA) describes the degree of the random differences in shape and size among two sides of a bilateral trait of the organisms and reflects the developmental instability of an organism, so we can use it to predict the effects on plant fitness. We evaluated the land-use change stress on seed FA levels, seed germination, and the subsequent seedling development of seed produced by trees that occur in an anthropized and a preserved area of seasonally tropical dry forests (STDF) in Brazil. We sampled 10 ten reproductive trees of Enterolobium contortisiliquum of each landscape condition, and then, 100 seeds per each tree were collected. Additionally, 50 seeds were randomly selected for each tree to determine plant fitness. Despite, we found no true FA in the community, the anthropized area had a lower seed nutritional quality and percentage of germination, and higher germination time of seeds produced than in preserved areas. The dry weight of the aerial part of seedlings did not differ between areas. However, root dry weight and total dry weight were higher in seedlings developed from seeds of anthropized than in preserved areas. Our findings show that seeds of E. contortisiliquum are not a sensitive biomarker to detect full stress conditions of habitat disturbance. However, we demonstrate that habitat disturbance negatively affects plant fitness, decreasing germination percentage, and nutritional quality, and increasing germination time. This fact has potential consequences on recruitment, establishment and survival of E. contortisiliquum in regenerating areas of STDF’s in Brazil.

Fluorescence emission spectra of target chloroplast metabolites (flavonoids, carotenoids, lipofuscins, pheophytins) as biomarkers of air pollutants and seasonal tropical climate.

Chloroplasts have luminescent metabolites-chlorophyll being the most known one-whose fluorescence emission may be a useful tool to assess the physiological status of the plant. Some antioxidants (flavonoids and carotenoids), and byproducts of membrane rupture (lipofuscins) and chlorophyll degradation (pheophytins), are chloroplasts' fluorescent metabolites directly involved in plant response to environmental stressors and pollutants and may act as a biomarker of stress. Here we hypothesized that climatic variations and air pollutants induce alterations in the emission profile of chloroplasts' fluorescent metabolites in Tillandsia usneoides (Bromeliaceae). To test this hypothesis, an active biomonitoring study was performed during 2years in five polluted sites located at the Metropolitan Region of Campinas (São Paulo State, Brazil), aiming to identify target chloroplasts' fluorescent metabolites acting as biomarkers of environmental stress. In situ identification and quantification of the intensity of the fluorescence emission from target metabolites (flavonoids, carotenoids, lipofuscins, and pheophytins) were performed by the observation of fresh leaf sections under confocal laser scanning microscopy. Changes in the profile of fluorescence emission were correlated with local climate and air pollution data. The fluorescence emissions of flavonoids and carotenoids varied seasonally, with significant influence of rainfall and NO2. Our results expand the use of T. usneoides as a bioindicator by using alterations in the fluorescence emission profile of chloroplast metabolites. This application may be especially interesting for NO2 biomonitoring.

Biomarker Histopatologi Hati Ikan Belanak (Mugil cephalus) Sebagai Peringatan Dini Toksisitas Kromium(Cr) di Muara Tukad Badung, Bali

The impact from the increased discharge of domestic and industrial waste, as well as other human activities, has had a significant negative impact on the quality of water in the TukadBadung River Estuary, which is a natural habitat for mullets (Mugil cephalus). In seeking to understand the response of aquatic organisms to this environmental change, one important biomarker of environmental stress is the histopathological features of fish liver. The measurement of water quality parameters in TukadBadung Estuary showed a normal range of dissolved oxygen (8.07), pH (7.01) and temperature (28.50C). However, the measurement results for the heavy metals chromium (Cr) in Station I (0.086 mg/L), Station II (0.099 mg/L), and Station III (0.099 mg/L) all exceeded the water quality standard threshold, based on the KepMen Negara LH No. 51 Tahun 2004 standard for seawater quality (seawater biota). The results of the observation of histopathological features of the liver organ of mullets (Mugil cephalus) in the TukadBadung Estuary revealed various physical damage, including signs of haemorrhagic, congestion, vascular degeneration, and focal necrosis.

Hypnea musciformis (Wulfen) J. V. Lamour. (Gigartinales, Rhodophyta) responses to gasoline short-term exposure: biochemical and cellular alterations

ABSTRACT Presence of toxic compounds in marine coastal waters has increased exponentially since Industrial Revolution. In this way, we aimed to evaluate biochemical and physiological changes occurring within Hypnea musciformis after short-term exposure to gasoline. Hypnea musciformis was cultivated without gasoline and then exposed to various concentrations of it (0.001 % - 1.0 %, v/v) for periods of 30 min, 1 h, 12 h and 24 h. A Pricncipal Compound Analysis of UV-vis spectral window (200-700 nm) was able to discriminate gasoline-exposed samples according to both exposure time and gasoline concentration. Changes in carotenoid profile composition were observed. Decreased carotenoid content was associated to gasoline exposure time, being lutein and trans-β-carotene the major compounds found. Higher gasoline concentrations negatively interfered with phenolic compounds accumulation. In addition, increased gasoline concentrations corresponded to decreased intracellular starch grains content as well as increased its deposition on cell wall external surface. Data obtained allow us to conclude that gasoline can damage Hypnea musciformis physiology and cell morphology. This is important, considering Hypnea musciformis carotenoids and phenolics are potential biomarkers of environmental stress investigated, as well as its increased cell wall thickness to avoid gasoline diffusion.

Early mitochondrial fragmentation is a potential in vitro biomarker of environmental stress

Mitochondria are essential dynamic organelles that ordinarily balance between fragmentation and fusion. Under stress conditions, a shift toward fragmentation or hyper-fusion is observed as a pro-survival reaction. Fragmentation of mitochondria occurs within minutes or hours after the beginning of the stress and occurs in response to a large number of stress stimuli, including those triggered by environmental contaminants. In this study, we tested whether the change in the mitochondrial phenotype, from tubular to fragmented, could be used as a potential environmental stress biomarker in cells and compared this response with the standard MTT-based viability assay. Firstly, we show that mitochondrial fragmentation induced by selected stressors not only increases with concentrations, but also correlates positively with the cytotoxicity. Secondly, we found that the mitochondrial fragmentation that occurs in the first hour of stress correlated with the viability measured after a 24-h stress, allowing the establishment of a linear relation between mitochondrial fragmentation at 1 h and the predictable associated cytotoxicity of environmental contaminants alone or in mixture. In conclusion, we have succeeded in developing a model of predictable 24 h-cytotoxicity given mitochondrial fragmentation at 1 h with a set of chemicals. This model has been successful applied to three environmental toxicants and to a set of two chemical mixtures. We thus propose that mitochondrial fragmentation is a response that could be used as an early in vitro biomarker of environmental stress for toxicants alone or in mixture.

Bioaccumulation of metals and biomarkers of environmental stress in Parablennius sanguinolentus (Pallas, 1814) sampled along the Italian coast

Heavy metal pollution is one of the greatest threats to the ecosystems because it degrades the habitat and is potentially toxic to wildlife and human populations. In the last few decades, bioaccumulation studies performed with a multimarker approach have been a valuable tool for the investigation of environmental and animal safety.We perform an analysis of a benthic teleost fish species – Parablennius sanguinolentus – sampled at several Italian coastal sites with different degrees of anthropogenic pressure. Our integrative analysis encompasses bioaccumulation of 10 metals, biomarkers of environmental stress (micronuclei and nuclear abnormalities) and neutral genetic variation (using sequences of the mtDNA control region).We find a clear and significant correlation of metal bioaccumulation with micronuclei and nuclear abnormalities, especially with undisputed genotoxic metals, such as Cd, Cr, Hg and Pb. Furthermore, the molecular genetic analysis revealed a decrease of genetic variability in the populations more subjected to anthropic pressure.

Enzymes as Biomarkers of Environmental Stress in African Catfish ( Clarias gariepinus ) in Osun State, Nigeria

Background.Many natural aquatic bodies have been contaminated with heavy metals released from domestic, industrial and other anthropogenic activities. Fish are an important bioindicator species and play an important role in the monitoring of water pollution.Objectives.This study shows the effect of heavy metals on the distribution of glutathione S-transferases (GST), catalase, rhodanese and 3-mercaptopyruvate sulphur transferase (3-MST) isolated from the liver, gills, fins and muscle of Clarias gariepinus.Methods.Glutathione S-transferase, catalase, rhodanese and 3-mercaptopyruvate S-transferase enzymes were isolated from the liver and gills of fish by homogenization of each tissue (with specific buffers for each enzyme) and centrifugation. Serial dilutions of the crude enzymes were then assayed for residual enzymatic activities using standard enzyme assay protocol.Results.The results showed heavy metals in the liver and muscle of the investigated fish. This study indicated significant accumulation of heavy metals in the tissues/organ of the fish from Ilesha, Osogbo and Yakoyo fish ponds. These are three main towns in Osun State where the major occupation is fish farming. The relationship between enzymatic activities and heavy metal content in C gariepinus tissue showed positive and significant (p<0.05) correlations between lead (Pb) and GST as well as chromium (Cr) and GST. This implies that higher concentrations of Pb and Cr induced the expression of greater GST activity in the fish tissue.Conclusions.The study concluded that the pattern of response of GST, catalase, rhodanese and 3-MST activities in the various organs/tissues of C gariepinus to the heavy metals suggests that the excitation or inhibitions of their activities are organ specific. Further biochemical studies of fish tissues/organs are needed to characterize the enzymatic changes associated with heavy metal pollution.

A comprehensive evaluation of the environmental quality of a coastal lagoon (Ravenna, Italy): Integrating chemical and physiological analyses in mussels as a biomonitoring strategy

This study aimed at evaluating the environmental quality of a coastal lagoon (Pialassa Piomboni, NW-Adriatic, Italy) by combining analyses of biomarkers of environmental stress and bioaccumulation of contaminants in marine mussels (Mytilus galloprovincialis) transplanted for 28days to six selected sites. Assessed biomarkers encompassed lysosomal endpoints, oxidative stress and detoxification parameters, specific responses to metals, neuro- and genotoxic substances; chemical analyses focused on PAHs, metals, pesticide and pharmaceuticals. Results showed up to a 67-fold bioaccumulation of 4- to 6-ring PAHs, including pyrene, fluoranthene, chrysene and benzo(ghi)perylene in transplanted mussels compared to reference conditions (T0). A 10-fold increase of Fe, Cr and Mn was observed, while pesticides and pharmaceuticals were not or slightly detected. The onset of a significant (p<0.05) general stress syndrome occurred in exposed mussels, as outlined by a 50–57.7% decrease in haemocytes lysosomal membrane stability and an increased lysosomal volume (22.6–26.9%) and neutral lipid storage (18.9–48.8%) observed in digestive gland. Data also revealed a diffuse lipofuscin accumulation (86.5–139.3%; p<0.05) in digestive gland, occasionally associated to a catalase activity inhibition in gill, indicating an increased vulnerability toward pro-oxidant factors. Higher levels of primary DNA damage (258%; p<0.05) and PAH accumulation were found in mussels exposed along the eastern shoreline, hosting a petrochemical settlement. Bioaccumulated metals showed a positive correlation with increased metallothionein content (85–208%; p<0.05) observed in mussels from most sites. Overall, the use of physiological and chemical analyses detected chronic alterations of the mussel health status induced by specific toxicological pathways, proving a suitable approach in the framework of biomonitoring programs of coastal lagoons.

BIOMARKER RESPONSE OF CLIMATE CHANGE INDUCED OCEAN ACIDIFICATION AND HYPERCAPNIA STUDIES ON BRACHYURIAN CRAB PORTUNUS PELAGICUS

A laboratory level microcosm analysis of the impacts of ocean acidification on the environmental stress biomarkers in Portunus pelagicus (Linneaus 1758)exposed to a series of pH regimes expected in the year 2100 (pH 7.5 and 7.0) and leakage from a sub-seabed carbon dioxide storage site (pH 6.5 - 5.5) was carried out. Levels of the antioxidant enzyme catalase, the phase II detoxification enzyme, glutathione S. transferase, the lipid peroxidation biomarker, malondialdehyde, acetylcholinesterase, and reduced glutathione were estimated in the tissues of the exposed animals to validate theses enzymes as biomarkers of Hypercapnia. The integrated biomarkers indicated a stress full environment in all animals except those exposed to the control seawater (pH 8.1). The reducing pH was also observed to be highly lethal to the animals exposed to lower pH levels which were obvious from the rate of mortality in a short term of exposure. The present study substantiates the role of biomarkers as an early warning of ocean acidification at a sub-lethal level.

An evaluation of feather corticosterone as a biomarker of fitness and an ecologically relevant stressor during breeding in the wild.

Feather corticosterone (CORT) levels are increasingly employed as biomarkers of environmental stress. However, it is unclear if feather CORT levels reflect stress and/or workload in the wild. We investigated whether feather CORT represents a biomarker of environmental stress and reproductive effort in tree swallows (Tachycineta bicolor). Specifically, we examined whether individual state and investment during reproduction could predict feather CORT levels in subsequently moulted feathers and whether those levels could predict future survival and reproductive success. Through a manipulation of flight cost during breeding, we also investigated whether an increase in stress level would be reflected in subsequently grown feathers, and whether those levels could predict future success. We found that CORT levels of feathers grown during moult did not (1) reflect past breeding experience (n=29), (2) predict reproductive output (n=18), or (3) respond to a manipulation of flight effort during reproduction (10 experimental, 14 control females). While higher feather CORT levels predicted higher return rate (a proxy for survival), they did so only in the manipulated group (n=36), and this relationship was opposite to expected. Overall, our results add to the mixed literature reporting that feather CORT levels can be positively, negatively, or not related to proxies of within-season and longer-term fitness (i.e., carryover effects). In addition, our results indicate that CORT levels or disturbances experienced during one time (e.g., breeding) may not carry over to subsequent stages (e.g., moult). We, therefore, petition for directed research investigating whether feather CORT represents exposure to chronic stress in feathers grown during moult.

Effect of ranching time on melanomacrophage centres in anterior kidney and spleen of Southern bluefin tuna, Thunnus maccoyii

Melanomacrophage centres (MMCs) are common in the haemopoietic tissue of fish and are an important component of the humoral immune response. Increasingly they are being studied as a biomarker of environmental stress in both wild and aquaculture fish stocks. Computer image analysis of histological sections of the head kidney and spleen of ranched Southern bluefin tuna (SBT) was used to investigate changes in MMCs over various stages of the ranching cycle. Histochemical pigment differentiation indicated haemosiderin, lipofuscin and melanin were present in MMCs of both the kidney and spleen, with kidney MMCs being highly positive for lipofuscin and melanin and spleen having high levels of haemosiderin and a lower level of melanin than kidney. The MMC area in the kidney of wild sampled SBT ranged from 0.41 ± 0.13% to 2.95 ± 0.26% and that in the spleen ranged from 0.35 ± 0.09% to 2.75 ± 0.86%. The MMC area in the spleen of SBT increased over the latter stages of ranching and at harvest compared to SBT sampled in the wild and at the end of tow. There was no statistically significant difference in the MMC area in the kidney of ranched SBT sampled at various stages. SBT appear to have a higher MMC area in haemopoietic organs than numerous other fish species, perhaps providing a greater capacity to deal with ‘wear and tear’ and increased immune-competence.

Hopanoids play a role in stress tolerance and nutrient storage in the cyanobacterium Nostoc punctiforme.

Hopanes are abundant in ancient sedimentary rocks at discrete intervals in Earth history, yet interpreting their significance in the geologic record is complicated by our incomplete knowledge of what their progenitors, hopanoids, do in modern cells. To date, few studies have addressed the breadth of diversity of physiological functions of these lipids and whether those functions are conserved across the hopanoid-producing bacterial phyla. Here, we generated mutants in the filamentous cyanobacterium, Nostoc punctiforme, that are unable to make all hopanoids (shc) or 2-methylhopanoids (hpnP). While the absence of hopanoids impedes growth of vegetative cells at high temperature, the shc mutant grows faster at low temperature. This finding is consistent with hopanoids acting as membrane rigidifiers, a function shared by other hopanoid-producing phyla. Apart from impacting fitness under temperature stress, hopanoids are dispensable for vegetative cells under other stress conditions. However, hopanoids are required for stress tolerance in akinetes, a resting survival cell type. While 2-methylated hopanoids do not appear to contribute to any stress phenotype, total hopanoids and to a lesser extent 2-methylhopanoids were found to promote the formation of cyanophycin granules in akinetes. Finally, although hopanoids support symbiotic interactions between Alphaproteobacteria and plants, they do not appear to facilitate symbiosis between N.punctiforme and the hornwort Anthoceros punctatus. Collectively, these findings support interpreting hopanes as general environmental stress biomarkers. If hopanoid-mediated enhancement of nitrogen-rich storage products turns out to be a conserved phenomenon in other organisms, a better understanding of this relationship may help us parse the enrichment of 2-methylhopanes in the rock record during episodes of disrupted nutrient cycling.

Diversity of cytosolic HSP70 Heat Shock Protein from decapods and their phylogenetic placement within Arthropoda

The 70kDa heat shock proteins (HSP70) are considered the most conserved members of the HSP family. These proteins are primordial to the cell, because of their implications in many cellular pathways (e. g., development, immunity) and also because they minimize the effects of multiple stresses (e. g., temperature, pollutants, salinity, radiations). In the cytosol, two ubiquitous HSP70s with either a constitutive (HSC70) or an inducible (HSP70) expression pattern are found in all metazoan species, encoded by 5 or 6 genes (Drosophila melanogaster or yeast and human respectively). The cytosolic HSP70 protein family is considered a major actor in environmental adaptation, and widely used in ecology as an important biomarker of environmental stress. Nevertheless, the diversity of cytosolic HSP70 remains unclear amongst the Athropoda phylum, especially within decapods.Using 122 new and 311 available sequences, we carried out analyses of the overall cytosolic HSP70 diversity in arthropods (with a focus on decapods) and inferred molecular phylogenies. Overall structural and phylogenetic analyses showed a surprisingly high diversity in cytosolic HSP70 and revealed the existence of several unrecognised groups. All crustacean HSP70 sequences present signature motifs and molecular weights characteristic of non-organellar HSP70, with multiple specific substitutions in the protein sequence. The cytosolic HSP70 family in arthropods appears to be constituted of at least three distinct groups (annotated as A, B and C), which comprise several subdivisions, including both constitutive and inducible forms. Group A is constituted by several classes of Arthropods, while group B and C seem to be specific to Malacostraca and Hexapoda/Chelicerata, respectively. The HSP70 organization appeared much more complex than previously suggested, and far beyond a simple differentiation according to their expression pattern (HSC70 versus HSP70). This study proposes a new classification of cytosolic HSP70 and an evolutionary model of the distinct forms amongst the Arthropoda phylum. The observed differences between HSP70 groups will probably have to be linked to distinct interactions with co-chaperones or other co-factors.

Conserved structure and expression of hsp70 paralogs in teleost fishes

The cytosolic 70KDa heat shock proteins (Hsp70s) are widely used as biomarkers of environmental stress in ecological and toxicological studies in fish. Here we analyze teleost genome sequences to show that two genes encoding inducible hsp70s (hsp70-1 and hsp70-2) are likely present in all teleost fish. Phylogenetic and synteny analyses indicate that hsp70-1 and hsp70-2 are distinct paralogs that originated prior to the diversification of the teleosts. The promoters of both genes contain a TATA box and conserved heat shock elements (HSEs), but unlike mammalian HSP70s, both genes contain an intron in the 5′ UTR. The hsp70-2 gene has undergone tandem duplication in several species. In addition, many other teleost genome assemblies have multiple copies of hsp70-2 present on separate, small, genomic scaffolds. To verify that these represent poorly assembled tandem duplicates, we cloned the genomic region surrounding hsp70-2 in Fundulus heteroclitus and showed that the hsp70-2 gene copies that are on separate scaffolds in the genome assembly are arranged as tandem duplicates. Real-time quantitative PCR of F. heteroclitus genomic DNA indicates that four copies of the hsp70-2 gene are likely present in the F. heteroclitus genome. Comparison of expression patterns in F. heteroclitus and Gasterosteus aculeatus demonstrates that hsp70-2 has a higher fold increase than hsp70-1 following heat shock in gill but not in muscle tissue, revealing a conserved difference in expression patterns between isoforms and tissues. These data indicate that ecological and toxicological studies using hsp70 as a biomarker in teleosts should take this complexity into account.

Biomarkers of environmental stress in gills of Pinna nobilis (Linnaeus 1758) from Balearic Island

In aquatic environments, bivalve molluscs are used as sentinel species for environmental biomonitoring. In this study Pinna nobilis specimens, the biggest Mediterranean bivalve, were collected in the Magaluf bay (Mallorca), a touristic location and in a pristine area of the Cabrera National Park as the control location. Histological and histochemical analysis in gills of specimens sampled from Magaluf exhibited evident tissue alterations with high presence of haemocytes. Lower acetylcholinesterase (AChE) activity and protein expression were also found in the gills of specimens collected from Magaluf compared with the control area. The determination of antioxidant enzyme activities, such as superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase, showed a higher activities of these antioxidant enzymes and total glutathione content in samples from Magaluf bay than in Cabrera. In conclusion, the present study demonstrated that human activities result in morphological tissue alterations and a reduced AChE activity in gills of P. nobilis. Moreover, these stressful environmental conditions induced an adaptive response in P. nobilis as evidenced by increased antioxidant defences and a decreased AChE activity. CapsuleThe human activities induce oxidative stress in P. nobilis as evidenced by increased antioxidant defences and a decreased acetylcholinesterase activity.