Energy metabolism enzymes inhibition by the combined effects of increasing temperature and copper exposure in the coral Mussismilia harttii

Effects of elevated temperature and copper exposure on the physiological state of the coral Galaxea fascicularis

The co-occurrence of elevated seawater temperature and local stressors (heavy metal contamination) affects the ecophysiology of phototrophic species, and represents a risk to the environmental quality of coral reefs. Therefore, we investigated the effects of both Cu alone and Cu in combination with elevated temperature (ET) on the physiology of the coral Galaxea fascicularis, and measured the parameters related to the photo-physiology and oxidative state. G.fascicularis is one of the dominant coral species in the South China Sea which exhibits strong adaptability to environmental stress. We exposed the common coral species G.fascicularis to a series of environmentally relevant concentrations of Cu at 29 °C (normal temperature, NT) and 32 °C (elevated temperature, ET) for 96 h. Single polyps were used in the experiments, which reduced individual variability when compared to the coral colonies. The results suggested that: i) Cu or ET had significant negative effects on the actual operating ability of photosystem Ⅱ (PSII), but not on the maximal chlorophyll fluorescence in darkness (Fv/Fm). ii) Symbiodiniaceae density was significantly reduced by high Cu concentrations, for Cu-NT and Cu-ET, a high concentration of Cu (40 μg/L) significantly impacted Symbiodiniaceae density, causing a 75.4% and 81.0% decrease, respectively. iii) the content of malondialdehyde (MDA) in coral tissues increased significantly under Cu-ET. iv) a certain range of copper concentration (25-30 μg/L) increased the pigment content of the Symbiodiniacea. Our results indicated that the combined stressors of Cu and ET made the coral tissue sloughed, caused the coral tissue damaged by lipid oxidation, reduced the photosynthetic capacity of the Symbiodiniacea, and led to the excretion of Symbiodiniacea.

Combined threats of climate change and contaminant exposure through the lens of bioenergetics

Organisms face energetic challenges of climate change in combination with suites of natural and anthropogenic stressors. In particular, chemical contaminant exposure has neurotoxic, endocrine-disrupting, and behavioral effects which may additively or interactively combine with challenges associated with climate change. We used a literature review across animal taxa and contaminant classes, but focused on Arctic endotherms and contaminants important in Arctic ecosystems, to demonstrate potential for interactive effects across five bioenergetic domains: (1) energy supply, (2) energy demand, (3) energy storage, (4) energy allocation tradeoffs, and (5) energy management strategies; and involving four climate change-sensitive environmental stressors: changes in resource availability, temperature, predation risk, and parasitism. Identified examples included relatively equal numbers of synergistic and antagonistic interactions. Synergies are often suggested to be particularly problematic, since they magnify biological effects. However, we emphasize that antagonistic effects on bioenergetic traits can be equally problematic, since they can reflect dampening of beneficial responses and result in negative synergistic effects on fitness. Our review also highlights that empirical demonstrations remain limited, especially in endotherms. Elucidating the nature of climate change-by-contaminant interactive effects on bioenergetic traits will build toward determining overall outcomes for energy balance and fitness. Progressing to determine critical species, life stages, and target areas in which transformative effects arise will aid in forecasting broad-scale bioenergetic outcomes under global change scenarios.

Hot and heavy: Responses of ragworms (Hediste diversicolor) to copper-spiked sediments and elevated temperature

Sediment contamination and seawater warming are two major stressors to macrobenthos in estuaries. However, little is known about their combined effects on infaunal organisms. Here we investigated the responses of an estuarine polychaete Hediste diversicolor to metal-contaminated sediment and increased temperature. Ragworms were exposed to sediments spiked with 10 and 20 mg kg^-1 of copper at 12 and 20 °C for three weeks. No considerable changes were observed in the expression of genes related to copper homeostasis and in the accumulation of oxidative stress damage. Dicarbonyl stress was attenuated by warming exposure. Whole-body energy reserves in the form of carbohydrates, lipids and proteins were little affected, but the energy consumption rate increased with copper exposure and elevated temperature indicating higher basal maintenance costs of ragworms. The combined effects of copper and warming exposures were mostly additive, with copper being a weak stressor and warming a more potent stressor. These results were replicable, as confirmed by two independent experiments of similar settings conducted at two different months of the year. This study suggests the higher sensitivity of energy-related biomarkers and the need to search for more conserved molecular markers of metal exposure in H. diversicolor.

Effects of microplastic combined with Cr(III) on apoptosis and energy pathway of coral endosymbiont

The combined effect of polyethylene (PE) microplastics and chromium (Cr(III)) on the scleractinian coral Acropora pruinosa (A. pruinosa) was investigated. The endpoints analysed in this study included the endosymbiont density, the chlorophyll a + c content, and the activity of enzymes involved in apoptosis (caspase-1, caspase-3), glycolysis (lactate dehydrogenase, LDH), the pentose phosphate pathway (glucose-6-phosphate dehydrogenase, G6PDH) and electron transfer coenzyme (nicotinamide adenine dinucleotide, NAD⁺/NADH). During the 7-day exposure to PE and Cr(III) stress, the endosymbiont density and chlorophyll content decreased gradually. The caspase-1 and caspase-3 activities increased in the high-concentration Cr(III) exposure group. Furthermore, the LDH and G6PDH activities decreased significantly, and the NAD⁺/NADH was decreased significantly. In summary, the results showed that PE and Cr(III) stress inhibited the endosymbiont energy metabolism enzymes and further led to endosymbiont apoptosis in coral. In addition, under exposure to the combination of stressors, when the concentration of Cr(III) remained at 1 × 10^-2 mg/L, the toxic effects of heavy metals on the endosymbiont were temporarily relieved with elevated PE concentrations. In contrast, when coral polyps were exposed to 5 mg/L PE and increasing Cr(III) concentrations, their metabolic activities were seriously disturbed, which increased the burden of energy consumption. In the short term, the toxic effect of Cr(III) was more obvious than that of PE because Cr(III) exposure leads to endosymbiont apoptosis and irreversible damage. This is the first study to provide insights into the combined effect of microplastic and Cr(III) stress on the apoptosis and energy pathways of coral endosymbionts. This study suggested that microplastics combined with Cr(III) are an important factor affecting the apoptosis and energy metabolism of endosymbionts, accelerating the collapse of the balance between the coral host and symbiotic endosymbiont.

The role of cuproptosis-related gene in the classification and prognosis of melanoma

Background

Melanoma, as one of the most aggressive and malignant cancers, ranks first in the lethality rate of skin cancers. Cuproptosis has been shown to paly a role in tumorigenesis, However, the role of cuproptosis in melanoma metastasis are not clear. Studying the correlation beteen the molecular subtypes of cuproptosis-related genes (CRGs) and metastasis of melanoma may provide some guidance for the prognosis of melanoma.

Methods

We collected 1085 melanoma samples in The Cancer Genome Atlas(TCGA) and Gene Expression Omnibus(GEO) databases, constructed CRGs molecular subtypes and gene subtypes according to clinical characteristics, and investigated the role of CRGs in melanoma metastasis. We randomly divide the samples into train set and validation set according to the ratio of 1:1. A prognostic model was constructed using data from the train set and then validated on the validation set. We performed tumor microenvironment analysis and drug sensitivity analyses for high and low risk groups based on the outcome of the prognostic model risk score. Finally, we established a metastatic model of melanoma.

Results

According to the expression levels of 12 cuproptosis-related genes, we obtained three subtypes of A₁, B₁, and C₁. Among them, C₁ subtype had the best survival outcome. Based on the differentially expressed genes shared by A₁, B₁, and C₁ genotypes, we obtained the results of three gene subtypes of A₂, B₂, and C₂. Among them, the B₂ group had the best survival outcome. Then, we constructed a prognostic model consisting of 6 key variable genes, which could more accurately predict the 1-, 3-, and 5-year overall survival rates of melanoma patients. Besides, 98 drugs were screened out. Finally, we explored the role of cuproptosis-related genes in melanoma metastasis and established a metastasis model using seven key genes.

Conclusions

In conclusion, CRGs play a role in the metastasis and prognosis of melanoma, and also provide new insights into the underlying pathogenesis of melanoma.

IDH2: A novel biomarker for environmental exposure in blood circulatory system disorders (Review)

As the risk of harmful environmental exposure is increasing, it is important to find suitable targets for the diagnosis and treatment of the diseases caused. Isocitrate dehydrogenase 2 (IDH2) is an enzyme located in the mitochondria; it plays an important role in numerous cell processes, including maintaining redox homeostasis, participating in the tricarboxylic acid cycle and indirectly taking part in the transmission of the oxidative respiratory chain. IDH2 mutations promote progression in acute myeloid leukemia, glioma and other diseases. The present review mainly summarizes the role and mechanism of IDH2 with regard to the biological effects, such as the mitophagy and apoptosis of animal or human cells, caused by environmental pollution such as radiation, heavy metals and other environmental exposure factors. The possible mechanisms of these biological effects are described in terms of IDH2 expression, reduced nicotine adenine dinucleotide phosphate content and reactive oxygen species level, among other variables. The impact of environmental pollution on human health is increasingly attracting attention. IDH2 may therefore become useful as a potential diagnostic and therapeutic target for environmental exposure-induced diseases.

Transcriptome alterations in zebrafish gill after exposure to different sizes of microplastics

Most studies on microplastics (MPs) focused on gut, liver, and brain, and MPs toxicity was size-dependent, but less has been reported on gill. Here, zebrafish were exposed to three sizes of MPs (45-53 μm, 90-106 μm, and 250-300 μm). Next, comparative transcriptome analysis and determination of physiological indices were performed in zebrafish gills to elucidate the size-associated toxicity of MPs to fish gills. Compared with the control, 60, 344, and 802 differentially expressed genes (DEGs) were identified after exposure to 45-53 μm, 90-106 μm, and 250-300 μm MPs for 5 days, respectively. More DEGs in treatment with bigger MPs suggested that bigger MPs might induce more changes in zebrafish gills than smaller ones. These DEGs were significantly enriched in the FoxO signaling, cellular senescence, circadian rhythm and p53 signaling pathways. Besides, 90-106 μm and 250-300 μm MPs treatments inhibited the cell cycle and prevented the apoptosis. The GSH content significantly increased after MPs exposure, suggesting the induction of oxidative stress. AChE and Na⁺/K⁺-ATPase activities were significantly lowered in all MPs treatments than in the control, suggesting the inhibition of neurotransmission and ion regulation. These changes might negatively influence the normal functioning of gills, such as osmoregulation, ion regulation, and respiration.

Lipid profiling of coral symbiosomes in response to copper-induced carbon limitation: A metabolic effect of algal symbionts on the host immune status

Copper micropollutants are known to constrain coral's assimilation of carbonate, affecting the carbon available to algal symbionts and thus inducing a light stress. However, little is known regarding the physiological relevance of lipid metabolism in coral symbiotic algae in a carbon-limited state. Membrane lipids exhibit multiple physicochemical properties that are collectively responsible for the dynamic structure of cells depending on the physiological demands of the circumstances. To gain insight into lipid metabolism's importance in this regard, glycerophosphocholine (GPC) profiling of symbiosomes in coral (Seriatopora caliendrum) exposed to environmentally relevant copper levels (2.2-7.5 μg/L) for 4 days was performed in this study. Notably, reducing the number of 22:6-processing GPCs and increasing that of lyso-GPCs likely addressed the demands of metabolizing excess light energy, such as affecting the membrane dynamics to promote mitochondrial uncoupling. The decrease in 22:6-processing GPCs additionally protected cellular membranes from elevated oxidative stress, reducing their susceptibility to peroxidation and offsetting oxidized lipid-induced effects on membrane dynamics. The change in plasmanylcholines specifically localized within the symbiosome membrane also met the membrane requirements for responding to oxidative stress conditions. Moreover, increasing the 20:4-possessing plasmanylcholines and lysoplasmanylcholines and reducing the 22:6-possessing plasmanylcholines likely resulted in an imbalance of the immune reaction, influencing the coral-algae symbiosis given the role of such plasmanylcholines in cell signaling. In summary, carbon limitations induced by copper enrichment lead to a shift in the membrane lipid profile of coral symbiosomes, accommodating themselves to light stress conditions while compromising the symbiosis's stability.

Combined effects of copper and microplastics on physiological parameters of Tubastrea aurea corals

Microplastics (MPs) have been a serious environmental problem because it can carry pollution like heavy metals and organic pollutants. However, the combined effect of MPs and bivalent copper ion (Cu(II)) on the coral azooxanthellate has been rarely studied. In the present study, the combined effects of PVC and Cu(II) on the physiological responses of Tubastrea aurea were studied. Our results showed that MPs alone enhanced the activity of catalase (CAT), superoxide dismutase (SOD), and reduced glutathione (GSH). The mixture groups had the same effects on the CAT and GSH, which enhanced CAT and GSH activity by 97% and 53% respectively. MPs alone and the combined treatment groups decreased the activity of lipid peroxide (LPO) and the content of metallothionein (MT) by 45% and 20% of the coral Tubastrea aurea. Cu(II) exposure always had negative effect on the physiological parameters of coral, and MPs decreased the toxicity of Cu(II) in the combined groups. This work is the first time to report the combined effects of Cu(II) and microplastics on azooxanthellate coral, which will provide important preliminary data for the following research.

Elevated Temperature and Exposure to Copper Leads to Changes in the Antioxidant Defense System of the Reef-Building Coral Mussismilia harttii

The frequency and severity of coral bleaching events have increased in recent years. Global warming and contamination are primarily responsible for triggering these responses in corals. Thus, the objective of this study was to evaluate the isolated and combined effects of elevated temperature and exposure to copper (Cu) on responses of the antioxidant defense system of coral Mussismilia harttii. In a marine mesocosm, fragments of the coral were exposed to three temperatures (25.0, 26.6, and 27.3°C) and three concentrations of Cu (2.9, 5.4, and 8.6 μg/L) for up to 12 days. Levels of reduced glutathione (GSH) and the activity of enzymes, such as superoxide dismutase (SOD), catalase (CAT), glutathione S-transferase (GST), and glutamate cysteine ligase (GCL), were evaluated on the corals and symbionts. The short exposure to isolated and combined stressors caused a reduction in GSH levels and inhibition of the activity of antioxidant enzymes. After prolonged exposure, the combination of stressors continued to reduce GSH levels and SOD, CAT, and GCL activity in symbionts and GST activity in host corals. GCL activity was the parameter most affected by stressors, remaining inhibited after 12-days exposure. Interesting that long-term exposure to stressors stimulated antioxidant defense proteins in M. harttii, demonstrating a counteracting response that may beneficiate the oxidative state. These results, combined with other studies already published suggest that the antioxidant system should be further studied in order to understand the mechanisms of tolerance of South Atlantic reefs.

Effects of Microplastics Exposure on the Acropora sp. Antioxidant, Immunization and Energy Metabolism Enzyme Activities

Microplastic pollution in marine environments has increased rapidly in recent years, with negative influences on the health of marine organisms. Scleractinian coral, one of the most important species in the coral ecosystems, is highly sensitive to microplastic. However, whether microplastic causes physiological disruption of the coral, via oxidative stress, immunity, and energy metabolism, is unclear. In the present study, the physiological responses of the coral Acropora sp. were determined after exposure to polyethylene terephthalate (PET), polyamide 66 (PA66), and polyethylene (PE) microplastic for 96 h. The results showed that there were approximately 4-22 items/nubbin on the surface of the coral skeleton and 2-10 items/nubbin on the inside of the skeleton in the MPs exposure groups. The density of endosymbiont decreased (1.12 × 105-1.24 × 105 cell/cm2) in MPs exposure groups compared with the control group. Meanwhile, the chlorophyll content was reduced (0.11-0.76 μg/cm2) after MPs exposure. Further analysis revealed that the antioxidant enzymes in coral tissues were up-regulated (Total antioxidant capacity T-AOC 2.35 × 10-3-1.05 × 10-2 mmol/mg prot, Total superoxide dismutase T-SOD 3.71-28.67 U/mg prot, glutathione GSH 10.21-10.51 U/mg prot). The alkaline phosphatase (AKP) was inhibited (1.44-4.29 U/mg prot), while nitric oxide (NO) increased (0.69-2.26 μmol/g prot) for cell signal. Moreover, lactate dehydrogenase (LDH) was down-regulated in the whole experiment period (0.19-0.22 U/mg prot), and Glucose-6-phosphate dehydrogenase (G6PDH) for cell the phosphate pentoses pathway was also reduced (0.01-0.04 U/mg port). Results showed that the endosymbiont was released and chlorophyll was decreased. In addition, a disruption could occur under MPs exposure, which was related to anti-oxidant, immune, and energy metabolism.

Soil acidification enhancing the growth and metabolism inhibition of PFOS and Cr(VI) to bacteria involving oxidative stress and cell permeability

Soil acidification is causing more and more attention, not only because of the harm of acidification itself, but also the greater harm to bacteria brought by some pollutants under acidic condition. Therefore, the toxicities of two typical soil pollutants (perfluorooctane sulfonate (PFOS) and chromium (Cr(VI)) to growth and metabolisms of soil bacteria (Bacillus subtilis as modol) were investigated. Under acidic condition of pH = 5, Cr(VI), PFOS and PFOS + Cr(VI) show stronge inhibition to bacteria growth up to 24.3%, 42.3%, 41.6%, respectively, and this inhibition was about 2-3 times of that at pH = 7. Moreover, acid stress reduces the metabolism of bacteria, while PFOS and Cr(VI) pollution futher strengthens this metabolic inhibition involving oxidative stress and cell permeability. The activities of dehydrogenase (DHA) and electron transport system (ETS) at pH = 5 exposed to Cr(VI), PFOS and combined PFOS + Cr(VI) was 21.5%, 16.9%, 23.2% and 8.9%, 32.2%, 19.1% lower than the control, respectively. However, the relative activity of DHA and ETS at pH = 7 are 5-8 and 2-13 times of that at pH = 5, respectively. Isoelectric point, cell surface hydrophobicity and molecular simulation analysis show that the corresponding mechanism is that acidic conditions enhance the interaction between bacteria and PFOS/Cr(VI) through hydrogen bonding, hydrophobic and electrostatic interactions. The results can guide the remediation of acid soil pollution, and provide a reference for the combined toxicity evaluation of heavy metals and micro-pollutants in acid soil.

Effects of acute microplastic exposure on physiological parameters in Tubastrea aurea corals

Pollution of marine environments with microplastic particles has increased rapidly during the last few decades and its impact on marine lives have recently gained attention in both public and scientific community. Scleractinian corals are the foundation species of coral reef ecosystems that are greatly affected by the microplastics (MPs), yet little is known about the effects of microplastics on the coral azooxanthellate. In the present study, effects of the exposure and ingestion of polyvinyl chloride (PVC), polyethylene (PE), polyethylene terephthalate (PET), and polyamide 66 (PA66) were studied on the physiological responses of Tubastrea aurea. Our results shows that coral ingested microplastics in four treatment groups and the exposure of microplastics inhibited the antioxidant capacity, immune system, calcification and energy metabolism of the coral Tubastrea aurea. Superoxide dismutase (SOD), catalase (CAT), alkaline phosphatase (AKP), and total antioxidant capacity (TAC) were reduced by 29.4%, 35.5%, 73.9%, and 52.2% in the corals exposed to PVC, respectively. PET microplastics impacted more severely on pyruvate kinase (PK), Na, K-ATPase (Na, K-ATP), Ca-ATPase (Ca-ATP), Mg-ATPase (Mg-ATP), Ca-Mg-ATPase (Ca, Mg-ATP), and glutathione (GSH). Activity of these enzymes decreases to 89.6%, 66.7%, 63.6%, 60.4%, 48.4%, and 50.5% respectively. We anticipate that this work will provide important preliminary data for better understanding the effects of MPs on stony corals azooxanthellate.

Metabolic status of the coral Mussismilia harttii in field conditions and the effects of copper exposure in vitro

It is widely known that metals can alter enzyme functioning, however, little is known about the mechanisms of metal toxicity in energy metabolism enzymes of corals. Thus, the present study had two objectives: firstly, we evaluated the activity of eight metabolic enzymes of the coral Mussismilia harttii to clarify metabolic functioning under field conditions. After that, we investigated the in vitro effect of copper (Cu) exposure in the activity of an enzyme representative of each metabolism stage. We evaluated enzymes involved in glycolysis (hexokinase, HK; phosphofructokinase, PFK; pyruvate kinase, PK and lactate dehydrogenase, LDH), Krebs cycle (citrate synthase, CS and isocitrate dehydrogenase, IDH), electron transport chain (electron transport system activity, ETS) and pentose phosphate pathway (glucose-6-phosphate dehydrogenase, G6PDH). The in vitro tests were performed through contamination of the reaction medium using Cu concentrations of 0, 1.4, 3.7 and 14.2 μg L^-1. The results showed that M. harttii has elevated activity of HK, PK and CS in field conditions compared to the activity of other energy metabolism enzymes evaluated. Moreover, lower activities of LDH and ETS in exposed samples were observed. In conclusion, in field conditions this species has elevated aerobic metabolism and glucose may be an important energetic fuel. Also, exposure to Cu in vitro caused inhibition of LDH and ETS by direct binding.

Isolated and combined effects of thermal stress and copper exposure on the trophic behavior and oxidative status of the reef-building coral Mussismilia harttii

Global warming and local disturbances such as pollution cause several impacts on coral reefs. Among them is the breakdown of the symbiosis between host corals and photosynthetic symbionts, which is often a consequence of oxidative stress. Therefore, we investigated if the combined effects of thermal stress and copper (Cu) exposure change the trophic behavior and oxidative status of the reef-building coral Mussismilia harttii. Coral fragments were exposed in a mesocosm system to three temperatures (25.0, 26.6 and 27.3 °C) and three Cu concentrations (2.9, 5.4 and 8.6 μg L^-1). Samples were collected after 4 and 12 days of exposure. We then (i) performed fatty acid analysis by gas chromatography-mass spectrometry to quantify changes in stearidonic acid and docosapentaenoic acid (autotrophy markers) and cis-gondoic acid (heterotrophy marker), and (ii) assessed the oxidative status of both host and symbiont through analyses of lipid peroxidation (LPO) and total antioxidant capacity (TAC). Our findings show that trophic behavior was predominantly autotrophic and remained unchanged under individual and combined stressors for both 4- and 12-day experiments; for the latter, however, there was an increase in the heterotrophy marker. Results also show that 4 days was not enough to trigger changes in LPO or TAC for both coral and symbiont. However, the 12-day experiment showed a reduction in symbiont LPO associated with thermal stress alone, and the combination of stressors increased their TAC. For the coral, the isolated effects of increase in Cu and temperature led to an increase in LPO. The effects of combined stressors on trophic behavior and oxidative status were not much different than those from the isolated effects of each stressor. These findings highlight that host and symbionts respond differently to stress and are relevant as they show the physiological response of individual holobiont compartments to both global and local stressors.

Larvae of the South Atlantic coral Favia gravida are tolerant to salinity and nutrient concentrations associated with river discharges

Rivers release freshwater, nutrients and pollutants into reefs. This type of environmental stress reduces coral larvae settlement and alter its energy metabolism. We investigated the tolerance of Favia gravida (Scleractinia) larvae to river discharges. We exposed larvae to (i) different salinities (25, 30, 35 and 40 PSU); and (ii) dilutions of river water containing nutrients and metals (0, 20, 40, 60, 80 and 100% river water) under control salinity of 35 PSU. We then examined settlement and larval enzymatic activity. No differences in settlement were detected among salinities. Settlement was also similar to control for larvae under 100% river water. Enzymatic activity for citrate synthase remained unaltered for all treatments. Lactate dehydrogenase activity was slightly altered under different salinities, suggesting a mild stress response. Findings suggest that F. gravida larvae are tolerant to a wide range of salinity and nutrient conditions and that this is a stress-tolerant species.

Combining elevated temperature with waterborne copper: Impacts on the energy metabolism of the killifish Poecilia vivipara

We have previously demonstrated in a companion work that acclimation to 28 °C potentiated waterborne copper (Cu) toxic effects in Poecilia vivipara through oxidative stress-related processes. In the present study, we hypothesized that these results were related to kinetic metabolic adjustments in enzymes from aerobic and anaerobic pathways. To test this, P. vivipara was acclimated to two temperatures (22 °C or 28 °C) for three weeks and then exposed to Cu (control, 9 or 20 μg/L) for 96 h. The activity of enzymes from glycolysis (pyruvate kinase [PK] and lactate dehydrogenase [LDH]), Krebs cycle (citrate synthase [CS]) and the electron transport chain system (ETS) were assessed in gills, liver and muscle. Interactive effects were only seen for hepatic LDH activity, as both metal exposure and heat stress, combined or not, inhibited this enzyme, showing a suppression in anaerobic pathways. Conversely, a Cu main effect was present in the liver, expressed as an elevation in ETS activity, showing an enhancement in hepatic aerobic metabolism likely related with the very energy-demanding process of metal detoxification. Moreover, this study shows that P. vivipara has a remarkable ability to compensate heat stress in terms of energy metabolism, as we could not observe acclimation temperature effects for most of the cases. Nonetheless, a tissue-dependent effect of elevated temperature was observed, as we could observe an inhibition in muscular CS activity. Finally, it is concluded that kinetic adjustments in terms of the energy metabolism are not related with the temperature-dependent elevation of Cu toxicity in P. vivipara as we previously hypothesized.

Can Palythoa cf. variabilis biochemical patterns be used to predict coral reef conservation state in Todos Os Santos Bay?

Coral reefs are one of the most diverse, complex and productive marine ecosystems on the planet. Global climate change and other anthropogenic impacts have had a strong impact on the equilibrium of these ecosystems and causing the denominated "coral reef crisis". One consequence of coral reef crisis is the phase shift in reef communities, where scleractinian corals responsible for the bioconstruction of the coralline building are replaced by macroalgae or soft corals. In Todos os Santos Bay (TSB) there is a rare case of phase shift caused by the soft coral Palythoa cf. variabilis. When in population outbreak, this coral species becomes dominant and leads to loss of scleractinian coral cover. Palythoa genus establishes a symbiotic relationship with dinoflagellate algae of the genus Symbiodinium, that is changed in phase shift coral reefs, but other alterations remain unknown. In this study, the metabolism (oxidative damage, antioxidant and biotransformation enzymes, electron transport chain activity and photosynthetic pigments) of P. cf. variabilis from reefs in different conservation states was studied to identify and relate if changes that may occur in the biochemical and metabolism of the coral might trigger the population outbreak, identify parameters recognizing if corals are in stress and assess if one or more parameters can reflect the level of stress organisms are experiencing. The results obtained evidenced a clear distinction in the biochemistry and metabolism of corals from conserved sites and sites in phase shift, and these changes may be the trigger for population outbreak. Some of the parameters were able to discriminate the level of stress corals are experiencing and may allow to recognize the most at-risk coral reefs that need immediate intervention and prevent the entry into or revert P. cf. variabilis outbreak and phase shift in coral reefs. Actions like these can be of vital importance for the preservation of TSB coral reefs and possibly for other threatened reefs worldwide.