Cadmium and copper toxicity in three marine macroalgae: evaluation of the biochemical responses and DNA damage

Copper multifaceted interferences during swine wastewater treatment in high-rate algal ponds: alterations on nutrient removal, biomass composition and resource recovery

Microalgae cultivation in swine wastewater (SW) allows the removal of nutrients and biomass production. However, SW is known for its Cu contamination, and its effects on algae cultivation systems such as high-rate algal ponds (HRAPs) are poorly understood. This gap in the literature limits the proposition of adequate concentrations of Cu to optimise SW treatment and resource recovery in HRAPs. For this assessment, 12 HRAPs installed outdoors were operated with 800 L of SW with different Cu concentrations (0.1-4.0 mg/L). Cu's interferences on the growth and composition of biomass and nutrient removal from SW were investigated through mass balance and experimental modelling. The results showed that the concentration of 1.0 mg Cu/L stimulated microalgae growth, and above 3.0 mg Cu/L caused inhibition accompanied by an accumulation of H₂O₂. Furthermore, Cu affected the contents of lipids and carotenoids observed in the biomass; the highest concentration was observed in the control (16%) and 0.5 mg Cu/L (1.6 mg/g), respectively. An innovative result was verified for nutrient removal, in which increased Cu concentration reduced the N-NH₄⁺ removal rate. In contrast, the soluble P removal rate was enhanced by 2.0 mg Cu/L. Removal of soluble Cu in treated SW reached 91%. However, the action of microalgae in this process was not associated with assimilation but with a pH increase resulting from photosynthesis. A preliminary evaluation of economic viability showed that the commercialisation of biomass considering the concentration of carotenoids obtained in HRAPs with 0.5 mg Cu/L could be economically attractive. In conclusion, Cu affected the different parameters evaluated in this study in a complex way. This can help managers consort nutrient removal, biomass production, and resource recovery, providing information for possible industrial exploitation of the generated bioproducts.

Marine enzymes: Classification and application in various industries

Oceans are regarded as a plentiful and sustainable source of biological compounds. Enzymes are a group of marine biomaterials that have recently drawn more attention because they are produced in harsh environmental conditions such as high salinity, extensive pH, a wide temperature range, and high pressure. Hence, marine-derived enzymes are capable of exhibiting remarkable properties due to their unique composition. In this review, we overviewed and discussed characteristics of marine enzymes as well as the sources of marine enzymes, ranging from primitive organisms to vertebrates, and presented the importance, advantages, and challenges of using marine enzymes with a summary of their applications in a variety of industries. Current biotechnological advancements need the study of novel marine enzymes that could be applied in a variety of ways. Resources of marine enzyme can benefit greatly for biotechnological applications duo to their biocompatible, ecofriendly and high effectiveness. It is beneficial to use the unique characteristics offered by marine enzymes to either develop new processes and products or improve existing ones. As a result, marine-derived enzymes have promising potential and are an excellent candidate for a variety of biotechnology applications and a future rise in the use of marine enzymes is to be anticipated.

Complete Remission of Vulvar Squamous Cell Carcinoma After Volumetric Modulated Arc Therapy in Copper Smelting and Purification Workers: A Case Report

Vulvar squamous cell carcinoma (VSCC) is the most frequent vulvar neoplasia, with invasiveness and metastasis. Typically, surgery is the preferred treatment. Radiotherapy is commonly used for unresectable locally advanced tumors and for early-stage patients who are at risk of serious complications from surgery or have a severe concomitant disease that prevents them from undergoing surgery. Compared to external irradiation, three-dimensional conformal radiotherapy (3D-CRT), and intensity-modulated radiotherapy (IMRT), various studies using volumetric modulated arc therapy (VMAT) alone in early-stage VSCC have been reported rarely. In this case, the patient had a large skin lesion and no lymph node metastasis. Surgical excision would seriously affect the urinary function and vulvar shape, so radical radiotherapy was given. To ensure the radiation dose for the radical treatment effect and to avoid high-dose radiation to normal organs, the volumetric intensity-modulated radiotherapy technique was chosen. After treatment, the patient's vulvar appearance returned to normal, and the tumor achieved complete remission without further surgery or chemotherapy, with no local recurrence or associated toxic side effects. This suggests that the efficacy of VMAT alone in early-stage VSCC is accurate and worthy of clinical promotion. The patient had been engaged in copper smelting and purification for many years, and it is unusual for her to have skin lesions with such a large surface area. In conjunction with her previous history of nasal basal cell carcinoma, the mechanism of oxidative stress during metal exposure should be further clinically examined, as it may be crucial in the formation and progression of malignancies.

Do we know the cellular location of heavy metals in seaweed? An up-to-date review of the techniques

Seaweeds are dominant organisms in coastal environments. However, in the context of global change, the integrity of these organisms is threatened by metal pollution. It is therefore important to understand how seaweeds are affected by metal concentrations in the water. Measuring the concentrations of metals in seaweed provides information about the effects of metal pollution on the seaweeds themselves and their ecosystems. Nonetheless, correct interpretation of this type of analysis requires knowledge of the cellular location of the pollutants, as the effects will differ depending on whether the metals are present in particles adhered to the surface, attached to external polysaccharides or dissolved in the cytoplasm. Thus, the objectives of this study were to compile the available information on the subcellular distribution of metals in seaweeds and to conduct a critical review of the information. We found that the existing studies provide contrasting, sometimes contradictory, results. Thus, metals have been detected entirely intracellularly and also mainly outside of the cells. In all of the studies reviewed, which used different techniques (mainly extracellular elution, X-ray microanalysis and centrifugation), methodological and/or conceptual problems were identified that raise questions about the effectiveness of each approach. To obtain reliable information about the distribution of metals in algal cells, further studies must be conducted that take into consideration the differences between elements and algal species and the limits of the methods used to measure the elements.

Accumulation of heavy metals (Cd, Cr, Cu, Mn, Pb, Ni, Zn) in sediments, macroalgae (Cryptonemia crenulata) and sponge (Cinachyrella kuekenthali) of a coral reef in Moín, Limón, Costa Rica: An ecotoxicological approach

Moín, on the Caribbean coast of Costa Rica, is a multi-use coastal zone with a variety of human activities that can cause metal pollution. With the purpose of assessing the current environmental burden due to heavy metal presence in the marine environment of Moín, and their bioaccumulation in organisms of the nearby coral reef, we determined seven metals in samples of bottom sediments, macroalgae (Cryptonemia crenulata) and sponge (Cinachyrella kuekenthali). The results were compared with samples from the southern Caribbean, an area with little human activity. Using ICP-MS, results showed a concentration range for sediments Mn > Cu > Zn > Cr > Ni > Pb > Cd, algae Mn > Cu > Zn > Ni > Cr > Pb > Cd and sponge Mn > Cu > Zn > Ni > Cr > Cd > Pb, relatively low concentrations overall and no differences observed between sites. Bioconcentration factor > 1 was determined for Cd, Cu, Ni and Zn, while concentrations in sediments were below the SQG thresholds. Our study provides the first data on metal concentrations in a macroalgae and a sponge from the Costa Rican Caribbean.

In search for potential biomarkers of copper stress in aquatic plants

Over the last few decades, the use of pesticides and discharge of industrial and domestic wastewater on water surfaces have increased. Especially, Copper (Cu) pollution in aquatic ecosystems could constitute a major health problem, not only for flora and fauna but also for humans. To cope with this challenge, environmental monitoring studies have sought to find Cu-specific biomarkers in terrestrial and aquatic flora and/or fauna. This review discusses the toxic effects caused by Cu on the growth and development of plants, with a special focus on aquatic plants. While copper is considered as an essential metal involved in vital mechanisms for plants, when in excess it becomes toxic and causes alterations on biomarkers: biochemical (oxidative stress, pigment content, phytochelatins, polyamines), physiological (photosynthesis, respiration, osmotic potential), and morphological. In addition, Cu has a detrimental effect on DNA and hormonal balance. An overview of Cu toxicity and detoxification in plants is provided, along with information regarding Cu bioaccumulation and transport. Awareness of the potential use of these reactions as specific biomarkers for copper contamination has indeed become essential.

Interactive effects of increasing atmospheric CO2 and copper exposure on the growth and photosynthesis in the young sporophytes of Sargassum fusiforme (Phaeophyta)

Little attention has been given to the combined effects of elevated atmospheric CO2-induced ocean acidification (OA) and heavy metal pollution on marine macroalgae at the young stage. This study investigated the mutual effects of copper (Cu) and elevated CO2 on the young sporophytes of brown macroalgae Sargassum fusiforme. A matrix of four copper concentrations, 0, 0.025, 0.075 and 0.15 mg‧L-1, and two levels of CO2 (ambient CO2: 400 μatm; elevated CO2: 1,000 μatm) were used. High concentration of copper exposure greatly depressed photosynthesis and growth of the young sporophytes of S. fusiforme by reducing the apparent photosynthetic efficiency (ɑ), maximum net photosynthetic oxygen evolution rate (Pmax), maximum photochemical quantum yield (Fv/Fm) and pigments content (Chl a and Car). While elevated CO2 alone had obscure impact on this alga. However, the inhibition of Cu stress on Fv/Fm was weakened by elevated CO2, which also decreased the light compensation point (Ic). Meanwhile, the Cu2+-induced ascent in the dark respiration rate (Rd) and superoxide dismutase (SOD) activity was mitigated under the growth with elevated CO2, suggesting an alleviated oxidative stress. Overall, we propose that, under CO2 enrichment condition, the young sporophytes of S. fusiforme may increase photosynthesis efficiency and synthesize less enzymatic antioxidants in face of increasing Cu stress.

Synergistic, antagonistic, and additive effects of heavy metals (copper and cadmium) and polycyclic aromatic hydrocarbons (PAHs) under binary and tertiary combinations in key habitat-forming kelp species of Chile

Heavy metals (HMs) and polycyclic aromatic hydrocarbons (PAHs) are persistent toxicants in coastal environments. Notably, in comparison to individual metal toxicity, knowledge about the effects of HMs and PAHs mixtures on kelps remains scarce. Accordingly, we performed in vitro experiments to determine the individual and combined effects of Cu, Cd, and PAHs on spore release, settlement, and germination on Macrocystis pyrifera and Lessonia spicata, two key-habitat forming kelp species of the coast of the Valparaíso Region in Chile. This region concentrates highly polluting industries, mainly due to unrestrained mining and fossil-fuel energy production. Single Cu, Cd, and PAHs treatments included concentrations in the ranges 5-200, 0.125-2000, and 0.05-100 μg/L, respectively, and a toxic-free treatment. Cu, Cd, and PAHs concentrations causing 20-50% (IC20, IC50) arrested spore release, settlement, and germination were determined, and the results shown in both species that single Cu, Cd, and PAHs IC20 values were generally lower on spore release than on spore settlement and germination, probably due to the absence of a cell wall in spores compared to later stages. Binary equitoxic IC20s mixture treatments changed from an antagonistic response to another with a greater inhibitory effect on spore release, from hour 1 to 7, whereas in IC50 treatments, the response was always antagonistic. The tertiary IC20 mixture of Cu+Cd+PAHs produced generally an antagonistic effect. Remarkably, all IC20 equitoxic mixture treatments showed a synergistic response on spore settlement in both kelps, suggesting that these toxicants are extremely harmful to kelp population persistence near highly polluted sites.

Effects of zinc and mercury on ROS-mediated oxidative stress-induced physiological impairments and antioxidant responses in the microalga Chlorella vulgaris

The rapid growth of industrialization and urbanization results in deterioration of freshwater systems around the world, rescinding the ecological balance. Among many factors that lead to adverse effects in aquatic ecology, metals are frequently discharged into aquatic ecosystems from natural and anthropogenic sources. Metals are highly persistent and toxic substances in trace amounts and can potentially induce severe oxidative stress in aquatic organisms. In this study, adverse effects of the two metal elements zinc (maximum concentration of 167.25 mg/L) and mercury (104.2 mg/L) were examined using Chlorella vulgaris under acute and chronic exposure period (48 h and 7 days, respectively). The metal-induced adverse effects have been analyzed through photosynthetic pigment content, total protein content, reactive oxygen species (ROS) generation, antioxidant enzymatic activities, namely catalase and superoxide dismutase (SOD) along with morphological changes in C. vulgaris. Photosynthetic pigments were gradually reduced (~32-100% reduction) in a dose-dependent manner. Protein content was initially increased during acute (~8-12%) and chronic (~57-80%) exposure and decreased (~44-56%) at higher concentration of the two metals (80%). Under the two metal exposures, 5- to 7-fold increase in ROS generation indicated the induction of oxidative stress and subsequent modulations in antioxidant activities. SOD activity was varied with an initial increase (58-129%) followed by a gradual reduction (~3.7-79%), while ~1- to 12-fold difference in CAT activity was observed in all experimental condition (~83 to 1605%). A significant difference was observed in combined toxic exposure (Zn+Hg), while comparing the toxic endpoint data of individual metal exposure (Zn and Hg alone). Through this work, lethal effects caused by single and combined toxicity of zinc and mercury were assessed, representing the significance of appropriate monitoring system to trim down the release of metal contaminants into the aquatic ecosystems.

Pollutant toxicology with respect to microalgae and cyanobacteria

Microalgae and cyanobacteria are fundamental components of aquatic ecosystems. Pollution in aquatic environment is a worldwide problem. Toxicological research on microalgae and cyanobacteria can help to establish a solid foundation for aquatic ecotoxicological assessments. Algae and cyanobacteria occupy a large proportion of the biomass in aquatic environments; thus, their toxicological responses have been investigated extensively. However, the depth of toxic mechanisms and breadth of toxicological investigations need to be improved. While existing pollutants are being discharged into the environment daily, new ones are also being produced continuously. As a result, the phenomenon of water pollution has become unprecedentedly complex. In this review, we summarize the latest findings on five kinds of aquatic pollutants, namely, metals, nanomaterials, pesticides, pharmaceutical and personal care products (PPCPs), and persistent organic pollutants (POPs). Further, we present information on emerging pollutants such as graphene, microplastics, and ionic liquids. Efforts in studying the toxicological effects of pollutants on microalgae and cyanobacteria must be increased in order to better predict the potential risks posed by these materials to aquatic ecosystems as well as human health.

The effect of elevated pCO2 on cadmium resistance of a globally important diatom

Cadmium (Cd) pollution is a widespread threat to marine life, and ongoing ocean acidification (OA) is predicted to impact bio-toxicity of Cd compounds. However, the cascading effects of changed Cd toxicity to marine primary producers are not well characterized. Here, we studied the impact of OA on Cd toxicity responses in a globally important diatom Phaeodactylum tricornutum under both ambient and elevated pCO₂ conditions. We found that increased pCO₂ alleviated the impact of additive Cd toxicity on P. tricornutum not only under controlled indoor experiments but also in outdoor mesocosm experiments that reflect more natural growth conditions. Transcriptome analysis suggested that genes involved in Cd efflux and phytochelatin production were up-regulated and genes involved in Cd influx were down-regulated in long-term selected lineages under elevated pCO₂. We further found a significant reduction of Cd transfer across trophic level, when the scallop Argopecten irradians was fed with Cd-exposed P. tricornutum previously cultured under elevated pCO₂. Our results indicate that after long-term selection of P. tricornutum exposed to future OA conditions (i.e. elevated pCO₂), the diatom alters its Cd detoxification strategy, which could have broader impacts on the bio-geochemical cycle of Cd in the marine ecosystem.

Toxicological effects of marine seaweeds: a cautious insight for human consumption

Marine environment is a rich and diverse source for many biologically active substances including functional foods and nutraceuticals. It is well exploited for useful compounds, natural products and aquaculture industry; and seaweeds is one of the major contributors in terms of both food security and healthy nutrition. They are well-known due to their enormous benefits and is consumed globally in many countries. However, there is lack of attention toward their toxicity reports which might be due toxic chemical compounds from seaweed, epiphytic bacteria or harmful algal bloom and absorbed heavy metals from seawater. The excess of these components might lead to harmful interactions with drugs and hormone levels in the human body. Due to their global consumption and to meet increasing demands, it is necessary to address their hazardous and toxic aspects. In this review, we have done extensive literature for healthy seaweeds, their nutritional composition while summarizing the toxic effects of selected seaweeds from red, brown and green group which includes- Gracilaria, Acanthophora, Caulerpa, Cladosiphon, and Laminaria sp. Spirulina, a microalgae (cyanobacteria) biomass is also included in toxicity discussion as it an important food supplement and many times shows adverse reactions and drug interactions. The identified compounds from seaweeds were concluded to be toxic to humans, though they exhibited certain beneficial effects too. They have an easy access in food chain and thus invade the higher trophic level organisms. This review will create an awareness among scientific and nonscientific community, as well as government organization to regulate edible seaweed consumption and keep them under surveillance for their beneficial and safe consumption.

Aquaculture and its by-products as a source of nutrients and bioactive compounds

Underutilized marine resources (e.g., algae, fish, and shellfish processing by-products), as sustainable alternatives to livestock protein and interesting sources of bioactive compounds, have attracted the attention of the researchers. Aquatic products processing industries are growing globally and producing huge amounts of by-products that often discarded as waste. However, recent studies pointed out that marine waste contains several valuable components including high-quality proteins, lipids, minerals, vitamins, enzymes, and bioactive compounds that can be used against cancer and some cardiovascular disorders. Besides, previously conducted studies on algae have shown the presence of some unique biologically active compounds and valuable proteins. Hence, this chapter points out recent advances in this area of research and discusses the importance of aquaculture and fish processing by-products as alternative sources of proteins and bioactive compounds.

Effect of metals of treated electroplating industrial effluents on antioxidant defense system in the microalga Chlorella vulgaris

The microalga Chlorella vulgaris is one of the prominent and most widely distributed green microalgae found in aquatic environments, often used in toxicity tests due to its sensitivity to various pollutants. To examine the toxicity of metals found in the effluent discharges from an electroplating industry, physicochemical parameters in the microalga C. vulgaris were measured. pH, turbidity, total dissolved solids, color, and the concentrations of metals such as chromium (1.97 mg/L), mercury (104.2 mg/L), and zinc (167.25 mg/L) were found exceeding the permissible limits. Several endpoints such as total protein content, reactive oxygen species (ROS) production, photosynthetic pigment contents, and antioxidant enzymatic activities, including those of superoxide dismutase (SOD) and catalase (CAT), were measured in C. vulgaris in response to treated electroplating industrial effluent (TEPIE). In addition, concentration-dependent morphological changes were also observed in response to TEPIE. Under both acute and chronic TEPIE exposure, increase in the ROS level was observed indicating increased production of ROS in C. vulgaris cells. The total protein and chlorophyll contents were found to be gradually decreasing in an effluent concentration-dependent manner. Moreover, lower concentrations of effluent stimulated the antioxidant enzyme systems. A concentration-dependent increase was observed in both SOD and CAT enzymatic activities. The results indicated toxic impairments by the effluent on the function of C. vulgaris in response to both acute and chronic exposure, indicating an urgent need of proper treatment processes/modification of the existing one of TEPIE, with continuous monitoring of the discharge of the pollutants into the aquatic ecosystems using biological assays.

Physiological response of Posidonia oceanica to heavy metal pollution along the Tyrrhenian coast

Heavy metal (HM) pollution of marine coastal areas is a big concern worldwide. The marine phanerogam Posidonia oceanica (L.) Delile is widely considered to be a sensitive bioindicator of water pollution due to its ability to sequester trace elements from the environment. The analysis of specific biomarkers, like reactive oxygen species scavengers, could allow us to correlate the physiological response of P. oceanica meadows to water pollution. In this study, we analysed the activity of some antioxidant enzymes and the expression level of the corresponding genes in the leaves of P. oceanica plants harvested from four meadows distributed along the Tyrrhenian coast; lipid peroxidation and the expression level of two genes related to HM response, metallothionein-2b and chromethylase, were also measured. The results of biochemical and molecular analyses were correlated with the concentration of some HMs, such as Cr, Cd, Cu, Ni and Pb, measured in P. oceanica leaves. We found a very strong antioxidant response in plants from the Murelle meadow whose HM concentration was the lowest for most of the analysed HMs, particularly Cu.

Joint effects of gamma radiation and cadmium on subcellular-, individual- and population-level endpoints of the green microalga Raphidocelis subcapitata

Interpreting and predicting the combined effects of toxicants in the environment is an important challenge in ecotoxicology. How such effects are connected across different levels of biological organisation is an additional matter of uncertainty. Such knowledge gaps are particularly prominent with regards to how ionising radiation interacts with contaminants. We assessed the response of twelve endpoints at the subcellular, individual and population level in a green microalga when exposed singly and jointly to gamma radiation and cadmium (Cd). We used a fully factorial experimental design where observed effects were compared to those predicted by the Independent Action (IA) model for mixture toxicity to determine whether they deviated from additivity. Subcellular endpoints (e.g., catalase, thiamine diphosphate, xanthophyll cycle pigments) showed an increased antioxidant and/or photoprotective response. However, our results indicate that this protection was not sufficient to prevent lipid peroxidation, which also increased with dose. At ecologically relevant doses, most interactions between gamma radiation and Cd regarding subcellular-, individual- and population-level endpoints were additive as predicted by the IA model. However, exposure to binary mixtures displayed antagonistic interactions between gamma radiation and Cd at the higher end of the tested dose spectrum. No correlations were observed between subcellular endpoints and higher-level endpoints, but there were linkages between individual and population endpoints. Our results suggest that antagonistic interactions between gamma radiation and Cd can occur at higher doses and that these interactions seem to disseminate from subcellular and individual to population level. Possible consequences for aquatic primary production and food-web interactions are discussed.

Metabolic responses of Ulva compressa to single and combined heavy metals

Accumulation of metals and metabolic responses were studied for two Cd and Cu concentrations (1 and 10 μM) either alone or as a combination in marine macroalga after 7 days of exposure. Cd accumulated more at a low dose (115 μg of Cd/g DW) but Cu at a high dose (378 μg of Cu/g DW); Cu suppressed Cd accumulation (by 57%). Na and Zn levels were unaffected, but higher metal doses depleted K and Ca levels. Higher metal concentrations strongly stimulated reactive oxygen species and depleted nitric oxide (NO) formation, but differences between the action of Cd and Cu were not extensive. Higher metal doses increased cell wall thickness with a potential relation to NO signal that is visible mainly in the apoplast in those treatments. A higher Cu dose depleted proline, ascorbic acid, and phenol levels more than Cd, whereas Cd elevated nonprotein thiols and ascorbic acid in combined treatments. An eventual role of malic or citric acid in metal chelation was not evident: malic acid level decreased in all treatments. The total content of fatty acids reached 16.7 mg/g DW in control with the quantitative order of PUFAs > SFAs > MUFAs; palmitic, vaccenic, linoleic, and α-linolenic acids were the major compounds. Cu was more toxic for fatty acids than Cd (even at 1 μM); mainly, PUFA levels strongly decreased (from 43% of total acids in control to 28.9% and 5.4% at 1 and 10 μM Cu treatment, respectively). Results are precisely and critically discussed in relation to limited literature focused on macroalgae, and a comparison with microalgae is also provided.

The impact of elevated atmospheric CO2 on cadmium toxicity in Pyropia haitanensis (Rhodophyta)

Cadmium is one of the major heavy metal pollutions in coastal waters, and it is well known that cadmium at trace concentration is toxic to macroalgae. Change in marine carbonate system and ocean acidification caused by elevated atmospheric CO₂ also alter physiological characteristics of macroalgae. However, less research is focused on the combined impacts of elevated CO₂ and cadmium pollution on the growth and physiology in macroalgae. In this study, the maricultivated macroalga Pyropia haitanensis (Rhodophyta) was cultured at three levels of Cd²⁺ (control, 4 and 12 mg L^-1) and two concentrations of CO₂, the ambient CO₂ (AC, 410 ppm) and elevated CO₂ (HC, 1100 ppm). The results showed that 12 mg L^-1 Cd²⁺ significantly suppressed the relative growth rate and superoxide dismutase activity in AC-grown P. haitanensis, while such inhibition extents by Cd²⁺ were alleviated in HC-grown algae. Cd²⁺ had no effects on efficiency of electron transport (α) and maximum electron transport rate (ETR_max), but α was increased by elevated CO₂. Cd²⁺ dramatically suppressed the maximum net photosynthesis oxygen evolution rate (NPR_m) and the minimum saturation irradiance (I_k) when the algal thalli were grown at AC, while such suppression of NPR_m by Cd²⁺ was much decreased when the thalli were grown at HC. Collectively, our results suggested that elevated CO₂ would alleviate Cd²⁺ toxicity on P. haitanensis.

Adverse effect of nano-TiO2 on the marine macroalgae Gracilaria lemaneiformis (Gracilariales, Rhodophyta): growth and antioxidant activity

Macroalgae, the major contributor of primary productivity in coastal seas, contribute to the material cycle and energy flow in marine ecosystems. The purpose of this work was to evaluate the toxic effect of nano-TiO₂ on the growth and antioxidant activity of Gracilaria lemaneiformis. An obvious inhibition of growth was observed in this study. The algae exposed to nano-TiO₂ showed a negative growth rate at 20 mg L⁻¹ and 40 mg L⁻¹ during the 15 days exposure. The concentration of soluble protein increased slightly during the first 3 days of exposure, but it gradually diminished thereafter due to the high concentrations of nano-TiO₂ and to prolonged exposure. Nano-TiO₂ caused oxidative damage in G. lemaneiformis; superoxide anions accumulated, and nitrate reductase activity decreased linearly with the increase in nano-TiO₂. Furthermore, extracts of G. lemaneiformis can scavenge DPPH· and hydroxyl radicals for their antioxidant capacity. However, the capacity to scavenge DPPH· and hydroxyl radicals in vitro decreased slightly with the increase in nano-TiO₂. The results from this work imply that macroalgae can be an effective biomarker of nano-TiO₂ contamination and can be useful indicators to evaluate the oxidative damage of increasing pollutants in marine ecosystems.

Macroalgae, the major contributor of primary productivity in coastal seas, contribute to the material cycle and energy flow in marine ecosystems.

Longitudinal survey of lead, cadmium, and copper in seagrass Syringodium filiforme from a former bombing range (Vieques, Puerto Rico)

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The United States Navy used half of Vieques, Puerto Rico and conducted military training exercises from 1947 to 2003.

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We conducted a longitudinal study to compare lead Pb, Cd and Cu content in a seagrass collected at a former bombing range in Puerto Rico.

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Pb, Cd, and Cu levels were consistently higher at the bombing range.

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High variability in Pb and Cd content were observed with up to 14 and 17 times higher than seagrass from the control site.

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Syringodium filiforme has the ability to bioaccumalate heavy metals from sediments and potentially can be used for restoration efforts.

Trace element composition in plant biomass could be used as an indicator of environmental stress, management practices and restoration success. A longitudinal study was conducted to compare Pb, Cd, and Cu content in seagrass Syringodium filiforme collected at a former bombing range in Puerto Rico with those of a Biosphere Reserve under similar geoclimatic conditions. Trace elements were measured by atomic absorption after dry-ashing of samples and extraction with acid. In general, levels of Pb, Cd, and Cu varied during 2001, 2003, 2005–2006, and 2013–2016. Results showed that bioaccumulated concentration of these trace elements were consistently higher, but not significant, at the bombing range site. As expected in polluted areas, greater variability in Pb and Cd content were observed in the military impacted site with levels up to 14 and 17 times higher than seagrass from the reference site, respectively. Although a decrease in Pb was observed after cessation of all military activities in 2003, the concentration in plant biomass was still above levels of ecological concern, indicating that natural attenuation is insufficient for cleanup of the site.

Toxic effect of nonylphenol on the marine macroalgae Gracilaria lemaneiformis (Gracilariales, Rhodophyta): antioxidant system and antitumor activity

The objective of the present work was to evaluate the toxic effect of nonylphenol (NP) on the antioxidant response and antitumor activity of Gracilaria lemaneiformis. An obvious oxidative damage was observed in this study. The thallus exposed to NP showed 1.2-2.0-fold increase in lipid peroxide and displayed a maximum level of 16.58 μmol g^-1 Fw on 0.6 mg L^-1 for 15-day exposure. The activities of antioxidant enzymes such as superoxide dismutase (SOD) and catalase (CAT) enhanced significantly by 1.1-3.2-fold and subsequently diminished at the high concentrations and prolonged exposure. The results of DNA damage in comet assay also supported that NP was obviously toxic on G. lemaneiformis with increasing the percentage of tail DNA in a dose-dependent manner. Furthermore, the ethanol extract of G. lemaneiformis (EEGL) did exhibit antitumor potential against HepG-2 cells. While decreased in cell inhibition, ROS generation, apoptosis, and caspase-3 in HepG-2 cells treated with the EEGL were observed when G. lemaneiformis was exposed to NP for 15 days, and which were related to exposure concentration of NP. These suggested that NP has strongly toxic effect on the antitumor activity of G. lemaneiformis. The results revealed in this study imply that macroalgae can be useful biomarkers to evaluate marine pollutions.

Biotechnological Applications of Marine Enzymes From Algae, Bacteria, Fungi, and Sponges

Diversity is the hallmark of all life forms that inhabit the soil, air, water, and land. All these habitats pose their unique inherent challenges so as to breed the "fittest" creatures. Similarly, the biodiversity from the marine ecosystem has evolved unique properties due to challenging environment. These challenges include permafrost regions to hydrothermal vents, oceanic trenches to abyssal plains, fluctuating saline conditions, pH, temperature, light, atmospheric pressure, and the availability of nutrients. Oceans occupy 75% of the earth's surface and harbor most ancient and diverse forms of organisms (algae, bacteria, fungi, sponges, etc.), serving as an excellent source of natural bioactive molecules, novel therapeutic compounds, and enzymes. In this chapter, we introduce enzyme technology, its current state of the art, unique enzyme properties, and the biocatalytic potential of marine algal, bacterial, fungal, and sponge enzymes that have indeed boosted the Marine Biotechnology Industry. Researchers began exploring marine enzymes, and today they are preferred over the chemical catalysts for biotechnological applications and functions, encompassing various sectors, namely, domestic, industrial, commercial, and healthcare. Next, we summarize the plausible pros and cons: the challenges encountered in the process of discovery of the potent compounds and bioactive metabolites such as biocatalysts/enzymes of biomedical, therapeutic, biotechnological, and industrial significance. The field of Marine Enzyme Technology has recently assumed importance, and if it receives further boost, it could successfully substitute other chemical sources of enzymes useful for industrial and commercial purposes and may prove as a beneficial and ecofriendly option. With appropriate directions and encouragement, marine enzyme technology can sustain the rising demand for enzyme production while maintaining the ecological balance, provided any undesired exploitation of the marine ecosystem is avoided.

The effect of cadmium on the growth and antioxidant response for freshwater algae Chlorella vulgaris

The objective of the present work was to evaluate the effect of exogenously applied cadmium on the physiological response of green algae Chlorella vulgaris. The study investigated the long-term effect (18 days) of cadmium on the levels of algae biomass, assimilation pigment composition, soluble protein, oxidative status (production of hydrogen peroxide and superoxide anion), antioxidant enzymes (such as superoxide dismutase, peroxidase, catalase and glutathione reductase enzyme) in C. vulgaris. The results showed that growth, the amount of chlorophyll a (Chl a), chlorophyll b (Chl b) and carotenoids gradually decreased with increasing cadmium over 18 days exposure. Cadmium at concentration of 7 mg L(-1) inhibited algal growth expressed as the number of cells. Our research found that C. vulgaris has a high tolerance to cadmium. Contents of chlorophylls (Chl a and Chl b) and carotenoids (Car) of C. vulgaris was significantly decline with rising concentration of cadmium (p < 0.05). The decrease of 54.04 and 93.37 % in Chl a, 60.65 and 74.32 % in Chl b, 50.00 and 71.88 % in total carotenoids was noticed following the treatment with 3 and 7 mg L(-1) cadmium doses compared with control treatment, respectively. Cadmium treatments caused a significant change in the physiological competence (calculated as chlorophyll a/b) which increased with increasing Cd(II) doses up to 1 mg L(-1) but decreased at 3 mg L(-1). While accumulation of soluble protein was enhanced by presence of cadmium, the treatment with cadmium at 3 and 7 mg L(-1) increased the concentration of soluble proteins by 88, 95.8 % in C. vulgaris, respectively. Moreover, low doses of cadmium stimulated enzymatic (superoxide dismutase, catalase and glutathione reductase) in C. vulgaris, The content of peroxidase increased with the increasing cadmium concentration, and had slightly decreased at the concentration of 7 mg L(-1), but was still higher than control group, which showed that cadmium stress at high concentration mainly peroxidase works in C. vulgaris. And therefore, suppressed reactive oxygen species (hydrogen peroxide and superoxide) accumulated. The present study also showed that cadmium increased oxidative stress and induced antioxidant defense systems against reactive oxygen species. The observation in here analyzed C. vulgaris after exposure to cadmium indicate that hydrogen peroxide, superoxide and peroxidase in the alga with exposure to Cd(II) seemed to be parameters as biomarkers for metal-induced oxidative stress.

Effects of Cu(2+) and Zn(2+) on growth and physiological characteristics of green algae, Cladophora

Effects of various concentrations of Cu(2+) and Zn(2+) (0.0, 0.1, 0.25, 0.5, or 1.0 mg/L) on the growth, malondialdehyde (MDA), the intracellular calcium, and physiological characteristics of green algae, Cladophora, were investigated. Low Zn(2+) concentrations accelerated the growth of Cladophora, whereas Zn(2+) concentration increases to 0.25 mg/L inhibited its growth. Cu(2+) greatly influences Cladophora growth. The photosynthesis of Cladophora decreased under Zn(2+) and Cu(2+) stress. Cu(2+) and Zn(2+) treatment affected the content of total soluble sugar in Cladophora and has small increases in its protein content. Zn(2+) induced the intracellular calcium release, and copper induced the intracellular calcium increases in Cladophora. Exposure to Cu(2+) and Zn(2+) induces MDA in Cladophora. The stress concent of Cu(2+) was strictly correlated with the total soluble sugar content, Chla+Chlb, and MDA in Cladophora, and the stress concent of Zn(2+) was strictly correlated with the relative growth rate (RGR) and MDA of Cladophora.

Protective Effect of L-Theanine on Cadmium-Induced Apoptosis in PC12 Cells by Inhibiting the Mitochondria-Mediated Pathway

L-Theanine is an amino acid derivative from green tea. The present work was aimed at the effect of L-theanine on neuron-like rat pheochromocytoma (PC12) cells stimulated with cadmium chloride. Treatment with L-theanine before cadmium exposure increased cell viability; the experiments of Annexin V/PI staining indicated that L-theanine inhibited cadmium-induced cell apoptosis. Meanwhile, L-theanine decreased ROS production and protected from cadmium-induced disruption of mitochondrial transmembrane potential. Compared with cadmium-treated cells, L-theanine could also decrease the ratio of Bax/Bcl-2, as well as the level of cleaved caspase-9, caspase-3 and poly(ADP-ribose) polymerase. Furthermore, L-theanine depresses cadmium-induced up regulation of phosphorylations of PI3K/Akt, MAPK ERK1/2, and JNK signaling. These data suggest that L-theanine pretreatment reduces severity of cadmium toxicity probably via antioxidant action. Therefore, it may be concluded that L-theanine could be exploited for prevention of cadmium-induced diseases.