RESUMO
Titanium (Ti), used in many dailyuse products, such as shampoos and sunscreen filters, in the form of TiO2 nanoparticles (NPs), may elicit adverse marine biota effects. Marine mammal Ti data is scarce, and subcellular distribution and detoxification information is non-existent. Ti concentrations and metalloprotein detoxification in Pontoporia blainvillei and Steno bredanensis dolphins from Southeastern Brazil were assessed. Metallothionein (MT) concentrations were determined spectrophotometrically, total and subcellular Ti, by ICP-MS and detoxification, by HPLC-ICP-MS. Ti detoxification occurred through MT complexation. Statistical Ti-MT associations were observed in S. bredanensis liver, indicating TiO2 NPs contamination, as Ti binds to MT only as NPs. MT-Ti correlations were observed for both the coastal (P. blainvillei) and offshore (S. bredanensis) dolphins, evidencing oceanic TiO2 diffusion. Ti detoxification through binding to reduced glutathione occurred in both species. Thermostable subcellular fractions are a valuable tool for cetacean Ti detoxification assessments and should be applied to conservation efforts.
Assuntos
Golfinhos/metabolismo , Titânio/metabolismo , Poluentes Químicos da Água/metabolismo , Animais , Brasil , Inativação MetabólicaRESUMO
Metals are subject to internal subcellular compartmentalization, altering their bioavailability. Thus, subcellular metal assessments are crucial in biomonitoring efforts. Metal distribution in three subcellular fractions (insoluble - ISF, thermolabile - TLF and thermostable - TSF) were determined by ICP-MS in Steno bredanensis specimens from Southeastern Brazil. Associations between metals, metallothionein (MT) and reduced glutathione (GSH) were also investigated. Differential metal-detoxification mechanisms were observed. MT detoxification was mostly noted for As, Cd, and Pb, while Cu, Cr, Hg, Ni, Se and Ti displayed lower MT-associations. Fe, Zn and Se, on the other hand, were poorly associated to MT, and mostly present in the ISF, indicating low bioavailability. This is the first report on subcellular Sn and Ti distribution in cetaceans and the first in this species in Brazil. Potential protective roles of essential metals against toxic elements are postulated. This study indicates that important biochemical detoxification information is obtained through subcellular fraction analyses in marine mammals.
Assuntos
Golfinhos/metabolismo , Monitoramento Ambiental/métodos , Metalotioneína/metabolismo , Metais/metabolismo , Frações Subcelulares/metabolismo , Poluentes Químicos da Água/metabolismo , Animais , Brasil , Glutationa/metabolismo , Inativação Metabólica , Metais Pesados/análise , Estanho/metabolismo , Titânio/metabolismoRESUMO
Dolphins are good bioindicators of the contamination status of marine ecosystems, since their dietary and habitat plasticity in both coastal and offshore ecotypes provide information on the trace elements levels originated from natural and anthropogenic sources. In this context, this study aimed to investigate provides mercury (Hg), selenium (Se) levels, trophic ecology and feeding environments of four small cetaceans (Tursiops truncatus, Steno bredanensis, Sotalia guianensis and Pontoporia blainvillei) inhabiting the central-northern coast of Rio de Janeiro State, southeastern Brazil. For the latter, δ15N and δ13C stable isotopes were used as indicators in this regard. Stable isotope values indicate that the four studied species have distinctive foraging habitats, coastal and least coastal, and occupy different trophic positions. The significant relationship found between muscle Hg and δ15N suggests that individual foraging preference remains relatively constant for the studied dolphin species over extended periods. The individual prey size and species are probably responsible for the differences found in Hg and Se concentrations in muscle tissue among all dolphin species. The vulnerable small coastal cetacean, P. blainvillei, which feeds on small teleost fish and squid, presented the lowest muscular Hg concentrations (less than 3.5 µg g-1 dry wt.). Meanwhile, S. bredanensis is more likely to uptake large amounts of trace elements among the four dolphin species, due to its feeding habits mainly being large offshore fish that accumulate high amounts of trace elements in organs and tissues. Differences found between Hg concentrations in fetus-mother pairs were much higher in S. guianensis than in P. blainvillei, suggesting that maternal contribution of Hg via placenta was more significant for the former.
Assuntos
Golfinho Nariz-de-Garrafa/metabolismo , Isótopos de Carbono/análise , Comportamento Alimentar , Mercúrio/análise , Isótopos de Nitrogênio/análise , Selênio/análise , Poluentes Químicos da Água/análise , Animais , Brasil , Ecossistema , Feminino , Peixes , Masculino , Músculos/químicaRESUMO
The trophic transfer of total mercury (THg) and its bioaccumulation from prey species to the predator fish Trichiurus lepturus was analysed in coastal waters of southeastern Brazil to evaluate the trace element dynamic in this predator-prey system. The isotopic (δ13C and δ15N) relation between this predator and its prey allowed inferences on prey assimilation and predator feeding habits. The THg increment varied from 4.5 to 19.5 times between prey and predator, with a biomagnification power of 0.59. The prey species could be divided into three groups regarding δ15N values: i) 13.6 to 13.2 (juvenile conspecifics, Pellona harroweri, and Peprilus paru); ii) 12.5 to 11.8 (Chirocentrodon bleekerianus, Lycengraulis grossidens, and Dorytheuthis plei); and iii) 10.5 (Xiphopenaeus kroyeri). Based on δ13C values, the prey groups were: i) -15.3 (X. kroyeri); ii) -17.6 to -16.8 (C. bleekerianus, D. plei, P. harroweri, P. paru, and juvenile conspecifics); and iii) -18.7 (L. grossidens). The values of THg and δ15N highlighted juvenile conspecifics as the main via of this trace element and the most assimilated prey. The isotopic relation between predator and its prey species showed a feeding activity preferably coastal and pelagic.
Assuntos
Isótopos de Carbono/farmacocinética , Peixes/metabolismo , Cadeia Alimentar , Mercúrio/farmacocinética , Isótopos de Nitrogênio/farmacocinética , Poluentes Químicos da Água/farmacocinética , Animais , BrasilRESUMO
In the present study, the concentration of trace elements, total mercury (Hg) and selenium (Se) and mercury forms (MeHg, Hginorg and HgSe) in the vulnerable coastal dolphins Pontoporia blainvillei and Sotalia guianensis were appraised and compared, using metallothioneins (MT) and glutathione (GSH) as biomarkers for trace element exposure. The trace element concentrations varied between muscle and liver tissues, with liver of all dolphin specimens showing higher Hg and Se concentrations than those found in muscle. Hg, MeHg and Hginorg molar concentrations showed a clear increase with Se molar concentrations in the liver of both dolphins, and Se concentrations were higher than those of Hg on a molar basis. Se plays a relevant role in the detoxification of MeHg in the hepatic tissue of both dolphins, forming Hg-Se amorphous crystals in liver. In contrast, MT were involved in the detoxification process of Hginorg in liver. GSH levels in P. blainvillei and S. guianensis muscle tissue suggest that these dolphins have different diving capacities. Muscle Hg concentrations were associated to this tripeptide, which protects dolphin cells against Hg stress.
Assuntos
Mergulho/fisiologia , Golfinhos/metabolismo , Glutationa/metabolismo , Mercúrio/análise , Metalotioneína/metabolismo , Selênio/análise , Poluentes Químicos da Água/análise , Animais , Biomarcadores/metabolismo , Brasil , Feminino , Inativação Metabólica , Fígado/metabolismo , Masculino , Mercúrio/farmacocinética , Compostos de Mercúrio/análise , Compostos de Mercúrio/farmacocinética , Compostos de Metilmercúrio/análise , Compostos de Metilmercúrio/farmacocinética , Músculos/metabolismo , Estresse Oxidativo/efeitos dos fármacos , Selênio/farmacocinética , Compostos de Selênio/análise , Compostos de Selênio/farmacocinética , Oligoelementos/análise , Oligoelementos/farmacocinética , Poluentes Químicos da Água/farmacocinéticaRESUMO
Magellanic penguins have been reported as good biomonitors for several types of pollutants, including trace-elements. In this context, selenium (Se), total mercury, methylmercury, inorganic mercury (Hg(inorg)), cadmium (Cd) and lead (Pb), as well as metallothionein (MT) levels, were evaluated in the feathers, liver and kidney of juvenile Magellanic penguins found stranded along the coast of Southern Brazil. The highest concentrations of all trace-elements and methylmercury were found in internal organs. Concentrations of Cd and Se in feathers were extremely low in comparison with their concentrations in soft tissues. The results showed that both Se and MT are involved in the detoxification of trace-elements (Cd, Pb and Hg(inorg)) since statistically significant relationships were found in liver. Conversely, hepatic Se was shown to be the only detoxifying agent for methylmercury.
Assuntos
Metalotioneína/análise , Compostos de Metilmercúrio/análise , Spheniscidae/metabolismo , Oligoelementos/análise , Animais , Oceano Atlântico , Biomarcadores , Brasil , Cádmio/análise , Cádmio/metabolismo , Monitoramento Ambiental , Plumas/química , Plumas/metabolismo , Feminino , Inativação Metabólica , Rim/química , Rim/metabolismo , Chumbo/análise , Fígado/química , Fígado/metabolismo , Masculino , Mercúrio/análise , Metalotioneína/metabolismo , Compostos de Metilmercúrio/metabolismo , Selênio/análise , Selênio/metabolismo , Oligoelementos/metabolismoRESUMO
Methylmercury (MeHg), inorganic mercury (Hginorg) and their biomagnification factors (BMF) were evaluated along a non-degraded Brazilian bay food web. Highly significant differences (p < 0.0001) were found between MeHg and Hginorg concentrations among all organisms (microplankton, shrimp, fish and dolphin). MeHg increased with increasing trophic position while Hginorg did not present the same pattern. BMF values for MeHg were higher than 1 for all trophic interactions from source to consumer, indicating that MeHg was transferred more efficiently and biomagnified over the entire web. Only one BMF exceeding one was observed for Hginorg (27) between microplankton and their consumer, planktivorous fish. BMF values for Hginorg were significantly different than those found for MeHg (20) at the base of the food web.
Assuntos
Monitoramento Ambiental , Cadeia Alimentar , Mercúrio/metabolismo , Compostos de Metilmercúrio/metabolismo , Poluentes Químicos da Água/metabolismo , Animais , Brasil , Golfinhos/metabolismo , Peixes/metabolismo , Zooplâncton/metabolismoRESUMO
Mercury (Hg), selenium (Se) and nitrogen (δ(15)N) stable isotope were assessed in a tropical food web of Rio de Janeiro's north coast. Isotopic data on muscle suggest a difference related to this parameter along the food web; where top-predators (cetacean and voracious fish) displayed heavier δ(15)N over the entire food web. Both top-predators presented similar δ(15)N values. Cetacean displayed higher Hg and lower Se than voracious fish. Five trophic positions (TP) were found in relation to primary consumer as baseline, ranging from 2.0 to 4.0. Positive relationships were found between trace-element and δ(15)N. The slope of regression equations (0.11 for Se and 0.21 for Hg) and food web magnification factors (2.4 for Se and 5.4 for Hg) showed that Hg presented higher rate of increase over the food web. Simultaneous measurements of trace-elements and ecological tracers emphasize the importance of TP into the trophic structure and distribution of Hg and Se throughout the food web.
Assuntos
Monitoramento Ambiental/métodos , Cadeia Alimentar , Mercúrio/análise , Selênio/análise , Poluentes Químicos da Água/análise , Animais , Brasil , Isótopos de Nitrogênio/análiseRESUMO
The growing ingestion of predatory fish by humans has increased their exposure to toxic chemicals. Mercury (Hg) is an exogenous and harmful trace-element that accumulates in all marine organisms. Selenium (Se) is nutritionally important as a micronutrient, but is potentially harmful at intakes above 1mg per day. Se:Hg molar ratios in excess of 1:1 are thought to counteract the adverse effects of Hg, protecting against Hg toxicity. Evaluation of the health risk posed by Hg exposure from seafood consumption requires concurrent consideration of Se content in the same individuals. This study evaluated the Se and Hg concentrations in the edible tissues of 652 individual samples of commonly consumed varieties of carnivorous and planktivorous fish, squid, mussel, shrimp and crab collected from south-eastern Brazil. The Se:Hg molar ratios showed significant variation among and within tropical seafood. All organisms presented Se concentration in muscle of less than 2.0µgg(-1), the maximum allowed selenium concentrations. Only seven individuals of a carnivorous fish species presented Hg in muscle above the maximum permissible limit of 0.5µgg(-1) established by WHO and Brazilian legislation for human consumption of most aquatic species. These same individuals also showed Se:Hg molar ratio of less than 1:1. Se:Hg molar ratios were found to decline with increasing fish length, potentially reducing Se-dependent protection. As a result of their rich Se, low Hg contents and Se:Hg molar ratios exceeding 1:1, nearly all species included in this study provide benefits for human consumption. Two popular seafoods in the region, the carnivorous fish Centropomus undecimalis (common snook) and Micropogonias furnieri (Atlantic croaker), had the most favorable Se:Hg molar ratio values of 33 and 21, respectively. Among the invertebrates, Xiphopenaeus kroyeri (seabob shrimp) and Loligo sanpaulensis (squid) had the most favorable Se:Hg molar ratio values, higher than 20. A selenium health benefit value based on the absolute amounts and relative proportions of Se and Hg in seafood was proposed as a more comprehensive seafood safety criterion.
Assuntos
Monitoramento Ambiental , Mercúrio/análise , Alimentos Marinhos/estatística & dados numéricos , Selênio/análise , Poluentes Químicos da Água/análise , Poluição Química da Água/estatística & dados numéricos , Animais , Organismos Aquáticos/metabolismo , Oceano Atlântico , Brasil , Peixes/metabolismo , Humanos , Mercúrio/metabolismo , Selênio/metabolismo , Poluentes Químicos da Água/metabolismoRESUMO
This research investigated whether environmental conditions, biological fish characteristics and anthropogenic impacts influenced mercury (Hg) assimilation into the muscle tissue of two fish species from two Brazilian bays, Ilha Grande Bay and Guanabara Bay. Fish and superficial water were collected in different periods. Hg was determined by CV-AAS. Methylmercury (MeHg) was identified and quantified by ECD-GC. Chlorophyll a concentrations in the water column indicated that Ilha Grande Bay and Guanabara Bay were oligotrophic and eutrophic, respectively. Hg in fish ranged from 2.10 to 870.17 µg kg(-1) dry wt. in Ilha Grande Bay and 40.90 to 809.24 µg kg(-1) dry wt. in Guanabara Bay. Slight differences were found between the length-normalized Hg concentrations and its percent of Hg in a voracious predator from the bays. In Guanabara Bay, where the presence of a chlor-alkali plant causes Hg input, the iliophagous fish species showed the highest length-normalized Hg concentrations and the voracious predator the lowest. Iliophagous fish is consumed by voracious predator and, consequently, acts as their MeHg food supply. Iliophagous fish from Ilha Grande Bay presented a higher percent of MeHg (80.0 %) than specimens from Guanabara Bay (54.5 %). This fact suggests that more MeHg was transferred from iliophagous fish to voracious predator in Ilha Grande Bay. At Guanabara Bay, the bioproduction is greater than that at Ilha Grande Bay, presenting the highest biomass in it ecosystem, which may subsequently dilute Hg and reduce its availability to the biota; i.e., influencing in Hg and MeHg availability throughout the food chain. Consequently, more MeHg is available in the aquatic environment of Ilha Grande Bay.