Efeitos do stress antrópico na qualidade alimentar de sistemas estuarinos

Doutoramento em Ciências do MarDe um modo geral, os poluentes constituem uma ameaça para os ecossistemas aquáticos, originando grande preocupação nas entidades responsáveis pela gestão destas áreas. Por exemplo, o uso intensivo e continuado de poluentes em áreas agrícolas, perto de zonas húmidas costeiras, como o estuário do Mondego (Portugal), levou à execução de programas de monitorização, ao longo dos últimos 20 anos, para proteger e recuperar este sistema aquático. De acordo com informações recentes, obtidas junto de cooperativas agrícolas do vale do Mondego, Primextra® Gold TZ é o herbicida mais utilizado em campos de cultura de milho, sendo um dos 20 herbicidas mais vendidos em Portugal. Por outro lado, o cobre é largamente utilizado na formulação de pesticidas. A avaliação ecológica e de risco têm sido rotineiramente focadas na exposição individual de substâncias químicas, o que pode subestimar os riscos associados à ação tóxica de misturas. Assim, os potenciais efeitos sinergísticos, que podem levar a consequências mais graves e imprevisíveis para os ecossistemas estuarinos e marinhos, são subestimados. Apesar do recente aumento do número de estudos relacionados com a toxicidade de misturas de contaminantes orgânicos (grupo de pesticidas) e de contaminantes inorgânicos (grupo de metais), há ainda falta de informação científica sobre os efeitos destas misturas. A avaliação de risco ambiental normalmente tem como objetivo estudar os efeitos de contaminantes em endpoints, como a sobrevivência, o crescimento ou a reprodução, uma vez que a quantidade de biomassa disponível tem efeitos importantes sobre os níveis tróficos subsequentes e o funcionamento global do ecossistema. No entanto, um aspeto muitas vezes esquecido é a qualidade do alimento disponível, que tem implicações importantes na transferência de energia e de nutrientes ao longo da cadeia trófica. Portanto, para melhor compreender os efeitos das perturbações antrópicas, são necessários mais estudos sobre o efeito de mistura de substâncias orgânica-inorgânica na qualidade do alimento de espécies aquáticas não-alvo. Assim, este trabalho visa determinar os efeitos do herbicida Primextra® e do cobre, usados individualmente e em mistura, sobre a qualidade alimentar em sistemas estuarinos, considerando as respostas populacionais e bioquímicas nutricionais de organismos chave não-alvo: a diatomácea marinha (Thalassiosira weissflogii) e o copépode estuarino calanoide (Acartia tonsa). As diatomáceas como os copépodes são grupos dominantes na comunidade planctónica no estuário do Mondego, constituindo uma cadeia trófica simples: produtor primário –consumidor primário. Foram também usados náuplios de uma terceira espécie (Artemia franciscana) para determinar os efeitos tóxicos e bioquímicos individuais de ambos os poluentes e para comparar as suas respostas com as das outras duas espécies planctónicas Para isso foram desenvolvidos ensaios de toxicidade, envolvendo exposições a substâncias químicas individuais e a misturas equitóxicas, para obtenção e modelação de dados bioquímicos indicadores da qualidade alimentar: teor de ácidos gordos (FA), incluindo ácidos gordos essenciais, teor de proteína e teor de substâncias reativas de ácido tiobarbitúrico (TBARS). Esta escolha baseou-se no facto dos ácidos gordos serem uma das mais importantes moléculas transferidas através da cadeia trófica, em teias alimentares aquáticas, podendo ser usados como um bom indicador de stress. Os resultados mostraram que T. weissflogii foi a espécie mais sensível ao herbicida seguida por A. tonsa (CE50 = 0,008 mg / L e CE50 = 0,925 mg / L, respetivamente), enquanto o copépode foi a espécie mais sensível ao metal, seguido por T. weissflogii (CE50 = 0,234 mg / L e CE50 = 0,383 mg / L, respetivamente). A análise estatística dos efeitos da mistura metal-herbicida sustentou um efeito sinergístico significativo sobre a sobrevivência do copépode (relativamente ao modelo de ação independente), e um efeito significativamente antagonístico sobre o crescimento da diatomácea (relativamente ao modelo de adição de concentração). A composição em ácidos gordos das espécies zooplanctónicas respondeu com elevada sensibilidade aos dois tipos de exposição (individual e de mistura),tendo-se observado o efeito mais nocivo na concentração de ácidos gordos essenciais de A. tonsa após a exposição à mistura de metal-herbicida: o seu valor diminuiu significativamente (5 vezes) em comparação com o controlo. Os resultados dos modelos lineares generalizados, baseados na variação da composição bioquímica (total de FA, FA essenciais, teor de proteína e TBARS), para as substâncias individuais e para a mistura, revelaram que os efeitos desta foram não-aditivos, para o conteúdo de FA essenciais de ambas as espécies planctónicas. Já a qualidade alimentar de A. tonsa (consumidor primário) foi mais sensível aos stressors químicos comparativamente a T. weissflogii (produtor), quando as duas espécies foram expostas a níveis iguais de contaminação. O presente estudo sugere que a exposição simultânea a um metal e a um herbicida pode afetar negativamente a qualidade alimentar de espécies planctónicas, em diferentes níveis tróficos. Esse efeito pode, potencialmente, ser transferido para níveis tróficos superiores e causar alterações importantes no fluxo de energia através do sistema estuarino e, posteriormente, para a dieta humana.Contaminants constitute a threat to aquatic communities and, thus to aquatic ecosystems. Pesticides are widely used to control pests and diseases in crop production. Among these agrochemicals, herbicides are commonly applied on crops to control adventive infestations. Thus, the intensive usage of pollutants in agriculture areas near ecological coastal wetlands led to the implementation of the Pesticide-Monitoring programs to recover aquatic systems, such as in the Mondego estuary, Portugal, since 1998. Nowadays, and according to the information from agricultural cooperatives of Mondego valley, the herbicide Primextra® Gold TZ is the herbicide most used in corn crops fields and is one of the 20 best-selling herbicides in Portugal, whereas copper is mainly used in pesticide`s formulation. Traditional effect and risk assessment have been routinely focused on exposures to single chemicals, which may underestimate the risks associated with toxic action of mixtures. Thus, the potential synergistic effects that may lead to more severe and unpredictable consequences for estuarine and marine ecosystems are ignored. Recently, there are an increasing number of studies dealing with toxicity of mixtures of either organic contaminants (group of pesticides) or inorganic contaminants (group of metals). However, studies with mixture experiments of metals and pesticides still remain scarce. Furthermore, environmental risk assessment typically aims to study the effects of contaminants on endpoints such as survival, growth or reproduction, since the available quantity of the biomass has important effects on the subsequent trophic levels and the overall ecosystem functioning. However, an often overlooked aspect of food availability is food quality, which has important implications on the energy and nutrient transfer through the food web. Further information about the effect of organic-inorganic mixture on the food quality of aquatic organisms, which are typical non-target species for these contaminants, is needed. This research aims to determine the effects of anthropogenic stressors on the food quality in estuarine systems by means of both, individual and mixture exposures, to the herbicide Primextra® and the metal copper, on the toxicity and nutritionally important biochemical parameters of key non-target organisms: a marine diatom (e.g. Thalassiosira weissflogii) and a estuarine calanoid copepod (e.g. Acartia tonsa) – both are dominant plankton groups in the Mondego estuary, constituting simple trophic food chain: primary producer – primary consumer. A third species, the brine shrimp Artemia franciscana (nauplii), was also added to the study to determine toxic and biochemical individual effects of both pollutants and to compare its response with the two other planktonic species. In this study a joint approach was applied, i.e. controlled laboratory experiments (toxicity tests and microcosm bioassays), involving single and equitoxic mixture exposures to chemical stressors combined with the further modelling of the obtained biochemical data: fatty acids (FA) content, including the essential FA, protein content and content of thiobarbituric acid reacting substances (TBARS) as important indicators of the food quality. Moreover, fatty acids are one of the most important molecules transferred across the plant-animal interface in aquatic food webs and can be used as good indicators of stress. The conducted lab incubations showed that T. weissflogii was the most sensitive species to the herbicide followed by A. tonsa (EC50 = 0.008 mg/L and EC50 = 0.925 mg/L, respectively), whereas the copepod was the most sensitive species to the metal in comparison to T. weissflogii (EC50 = 0.234 mg/L and EC50 = 0.383 mg/L, respectively). The statistical analysis of mixture effects revealed that the metal-herbicide mixture acted significantly synergistic on the copepod survival (relatively to the independent action model), while acted significantly antagonistic on the diatom growth (relatively to the concentration addition model). FA composition of zooplanktonic species responded with higher sensitivity to both, the individual and mixture exposures with the most harmful effect on the essential FA of A. tonsa after exposure to the metal-herbicide mixture: their amount significantly decreased (5 times) compared to the uncontaminated treatment. The results of the generalized linear models fitted to the experimentally observed responses of biochemical composition (total FA, essential FA, protein and TBARS contents) to the single substances and the mixture revealed that effects of the copper-Primextra® mixture were non-additive for the essential FA content of both planktonic species. They further showed that the food quality of the species from higher trophic level, i.e. primary consumer A. tonsa was more sensitive to the chemical stressors than for the primary producer T. weissflogii, when species were exposed to the equal levels of contamination. The study concludes that simultaneous exposure to metal and pesticide contaminants adversely affect the food quality of planktonic species at different trophic levels and this can potentially be transferred to higher trophic levels and cause important implications for the energy flow through the estuarine system and subsequently the human diet.Verontreinigingen vormen een bedreiging voor in het water levende gemeenschappen en daarom ook voor aquatische ecosystemen. Pesticiden worden op grote schaal gebruikt om ziekten en plagen in de plantaardige productie te controleren. Onder deze landbouwchemicaliën, worden herbiciden vaak toegepast op gewassen om adventive besmettingen te controleren. Zo heeft het intensief gebruik van verontreinigende stoffen in landbouwgebieden in de buurt van ecologische wetlands geleid tot de uitvoering van Pesticide-Monitoring-programma's sinds 1998 om aquatische systemen, zoals in het Mondego estuarium (Portugal) te herstellen. Op basis van de huidige informatie uit agrarische coöperaties van de Mondego-vallei blijkt dat de herbicide Primextra® Gold TZ de meest gebruikte herbicide is in maïsvelden en dat het één van de 20 best verkopende herbiciden in Portugal is waarbij koper het voornaamste element van de samenstelling vormt. Traditionele effect- en risicobeoordeling zijn routinematig gericht op blootstelling aan enkele chemische stoffen, die de risico's van de toxische werking van mengsels kunnen onderschatten. Zo worden de potentiële synergetische effecten die kunnen leiden tot meer ernstige en onvoorspelbare gevolgen voor estuariene en mariene ecosystemen genegeerd. Recent zijn er een toenemend aantal studies gebeurd die toxiciteit van mengsels van ofwel organische verontreinigingen (groep pesticiden) of anorganische verontreinigingen (groep metalen) onderzoeken. Studies met mengselexperimenten van metalen en pesticiden zijn nog steeds schaars. Bovendien heeft milieurisicobeoordeling typisch tot doel om de effecten van contaminanten op eindpunten zoals overleving, groei of reproductie te bestuderen, omdat de beschikbare hoeveelheid biomassa belangrijke gevolgen heeft voor de hogere trofische niveaus en het algemeen functioneren van het ecosysteem. Echter, een vaak vergeten aspect van de voedselbeschikbaarheid is de kwaliteit van het voedsel, wat belangrijke gevolgen kan hebben voor de energie- en voedingsstoffenoverdracht in de voedselketen. Verdere informatie over het effect van de organische-anorganische mengsel op de voedselkwaliteit van het aquatische organismen, die vaak geen doelsoorten voor deze verontreinigingen zijn, is daarom noodzakelijk. Dit onderzoek heeft tot doel de effecten van antropogene stressoren op de voedselkwaliteit in estuariene systemen te bepalen door middel van blootstelling aan zowel individuele concentraties als mengsels van herbicide Primextra® en het metaal koper, op de toxiciteit en de nutritioneel relevante biochemische parameters van belangrijke non-target organismen: een mariene diatomee (bijv Thalassiosira weissflogii) en een estuariene calanoid copepod (bijv Acartia tonsa) - beide zijn één van de belangrijkste planktongroepen in de Mondego estuarium, die een eenvoudig trofische voedselketen voorstellen tussen primaire producent en primaire consument. Een derde soort, (de nauplii van) Artemia franciscana, werd ook toegevoegd aan de studie om de toxische en biochemische individuele effecten van beide polluenten te bepalen en om zijn respons te vergelijken met de twee andere planktonsoorten. In deze studie werd een gezamenlijke aanpak toegepast waanbij laboratoriumexperimenten (toxiciteitstesten en microcosmos bioassays), met blootstelling aan één of aan een equitoxische mengsel van chemische stressoren, werden gecombineerd met het verder modellering van de verkregen biochemische data: vetzuren, met bijzondere aandacht voor essentiële vetzuren, eiwitgehalte en de inhoud van thiobarbituurzuur reagerende stoffen (TBARS) als belangrijke indicatoren voor voedselkwaliteit. Daarenboven zijn vetzuren één van de belangrijkste moleculen overgedragen aan de plant-dier interface in aquatische voedselwebben en kunnen ze gebruikt worden als goede indicatoren van stress. De uitgevoerde labincubaties toonden dat T. weissflogii de meest gevoelige soort was voor de herbicide gevolgd door A. tonsa (EC50 = 0.008 mg / L en EC50 = 0.925 mg / L, respectievelijk), terwijl de copepoden het meest gevoelig waren voor het metaal tenopzichte van T. weissflogii (EC50 = 0.234 mg / L en EC50 = 0.383 mg / L respectievelijk). De statistische analyse van mengseleffecten bewees dat het metaal-herbicide mengsel significant synergistisch werkte op de overleving van de copepoden (ten opzichte van de onafhankelijke actiemodel), terwijl significante antagonistische effecten op de diatomeeëngroei optraden (ten opzichte van de concentratieadditiemodel). FA samenstelling van de zooplanktonische soorten reageerde met een hogere gevoeligheid op beide, individuele en mengsel, blootstellingen met de meest schadelijke gevolgen voor de essentiële vetzuren van A. tonsa na blootstelling aan het metaal-herbicide mengsel: de vetzuurconcentratie daalde aanzienlijk (tot 5 maal) ten opzichte van de onbesmette behandeling. De resultaten van de gegeneraliseerde lineaire modellen toegepast op de experimenteel waargenomen responsen van biochemische samenstelling (totale vetzuren, essentiële vetzuren, eiwit- en TBARS concentraties) tenopzichte van de afzonderlijke stoffen en van het mengsel toonden aan dat effecten van het koper-Primextra® mengsel niet additief waren voor de concentratie van de essentiële vetzuren van beide planktonische soorten. Verder bleek de voedselkwaliteit van de soort op het hoger trofisch niveau, namelijk de primaire consument A. tonsa, gevoeliger te zijn voor de chemische stressoren dan de primaire producent T. weissflogii, wanneer soorten werden blootgesteld aan gelijke verontreinigingsniveaus. De studie concludeert dat gelijktijdige blootstelling aan metalen en pesticiden verontreinigingen een negatieve invloed heeft op de voedselkwaliteit van planktonische soorten op verschillende trofische niveaus en dit kan mogelijk worden overgedragen naar hogere trofische niveaus met belangrijke gevolgen voor de energiestroom door het estuariene systeem en vervolgens ook voor het menselijke dieet

Biochemical and toxicological effects of organic (herbicide Primextra® Gold TZ) and inorganic (copper) compounds on zooplankton and phytoplankton species

In Europe, mainly in the Mediterranean region, an intensive usage of pesticides was recorded during the past 30 years. According to information from agricultural cooperatives of the Mondego valley (Figueira da Foz, Portugal), Primextra® Gold TZ is the most used herbicide in corn crop fields and one of the 20 best-selling herbicides in Portugal. Copper is mainly used in pesticide formulations. This study aims to determine the ecotoxicological and biochemical (namely fatty acid profiles) effects of the herbicide Primextra® Gold TZ and the metal copper on marine plankton. The organisms used in this study are three planktonic species: the marine diatom Thalassiosira weissflogii, the estuarine copepod Acartia tonsa and nauplii of the marine brine shrimp Artemia franciscana. Fatty acids (FAs) are one of the most important molecules transferred across the plant-animal interface in aquatic food webs and can be used as good indicators of stress. The conducted lab incubations show that T. weissflogii is the most sensitive species to the herbicide followed by A. tonsa (EC50 =0;0.0078 mg/L and EC50 =0;0.925 mg/L, respectively), whereas the copepod was the most sensitive species to the metal followed by T. weissflogii (EC50 =0.234 mg/L and EC50 =0.383 mg/L, respectively). A. franciscana was the most tolerant organism both to the herbicide and to the metal (EC50 =20.35 mg/L and EC50 = 18.93 mg/L, respectively). Changes in the FA profiles of primary producer and primary consumers were observed, with the increase of saturated FA and decrease of unsaturated FA contents, especially of highly unsaturated FAs that can be obtained mainly from food and therefore are referred to as ‘essential FA’. The study suggests that discharges of Primextra® Gold TZ or other pesticides mainly composed by copper may be a threat to plankton populations causing changes in the FA contents and thus in their nutritive value, with severe repercussions for higher trophic levels and thus the entire food web

Ecotoxicological and biochemical mixture effects of an herbicide and a metal at the marine primary producer diatom Thalassiosira weissflogii and the primary consumer copepod Acartia tonsa

Mixture effects of chemicals and their potential synergistic interactions are of great concern to the public and regulatory authorities worldwide. Intensive agricultural activities are leading to discharges of chemical mixtures to nearby estuarine and marine waters with possible adverse effects on the aquatic communities and for the trophic food web interlinking these communities. Further information about the impacts of these stressors on aquatic organisms is needed. This study addresses ecotoxicological and biochemical effects of single and mixtures of the metal copper and the herbicide Primextra® Gold TZ on the marine diatom Thalassiosira weissflogii and on the estuarine calanoid copepod Acartia tonsa by determining growth rate and survival, respectively, and changes on fatty acid(FA) profiles in both species. Mixture effects on diatom species revealed that copper and Primextra® acted most likely additively with respect to the concentration addition (CA) and independent action (IA) models with model deviation ratios (MDR), 0.752 and 1.063, respectively. For the copepod species, copper and Primextra® were most likely non-interactive with respect to the CA model (MDR = 1.521) but acted most likely synergistically with respect to the IA model (MDR = 2.026). A significant decline in the absolute FA concentration was observed for copepod species after mixture exposure including a considerable decrease of essential FAs that cannot be synthesized de novo by these grazers. We concluded that the mixture effects are more hazardous for primary consumer than for primary producer species in terms of both abundance and biomass quality, suggesting a potential for harmful effects for higher trophic levels and thus a decrease in energy flow through the ecosystem

STUDY OF MICRONUTRIENTS INTAKE IN PATIENTS WITH VARIOUS THYROID DISEASES

The study design included several groups of patients, who were divided according various thyroid diseases. A comparative study of trace element values (copper, selenium, magnesium and zinc) in nails was performed. Low median selenium content, suggesting its low consumption, has been observed in all groups of the study. The level of selenium intake may be characterized as severe deficit. Moreover, most patients included in the study have reported mild deficits of manganese and copper intake and a moderate zinc deficiency

Effects of a herbicide and copper mixture on the quality of marine plankton

Pesticides and metals are often used in agriculture and are therefore often simultaneously discharged to nearby estuarine and marine areas. The effects of this organic-inorganic chemical mixture on food quality of aquatic organisms are currently unknown. In this study we test if a mixture of copper (inorganic) and the herbicide Primextra (R) Gold TZ (organic) affects the quality of the diatom Thalassiosira weissfiogii and the copepod Acartia tonsa - two key species that fuel the local food-web. We quantified quality (i.e. energy content as food for the next trophic level) in terms of fatty acids, proteins and thiobarbituric acid reacting substances. We found non additive effects (positive and negative) of the metal-herbicide mixture on the diatom and copepod species. In general, nutritionally important biochemical parameters of Acartia tonsa were most sensitive to the chemical stressors

The Ability of the Nitric Oxide Synthases Inhibitor T1023 to Selectively Protect the Non-Malignant Tissues

Previously, we showed that a nitric oxide synthase (NOS) inhibitor, compound T1023, induces transient hypoxia and prevents acute radiation syndrome (ARS) in mice. Significant efficacy (according to various tests, dose modifying factor (DMF)—1.6–1.9 against H-ARS/G-ARS) and safety in radioprotective doses (1/5–1/4 LD10) became the reason for testing its ability to prevent complications of tumor radiation therapy (RT). Research methods included studying T1023 effects on skin acute radiation reactions (RSR) in rats and mice without tumors and in tumor-bearing animals. The effects were evaluated using clinical, morphological and histological techniques as well as RTOG classification. T1023 administration prior to irradiation significantly limited the severity of acute RSR. This was due to a decrease in radiation alteration of the skin and underlying tissues, and the preservation of the functional activity of cell populations that are critical in the pathogenesis of radiation burn. The DMF values for T1023 for skin protection were 1.4–1.7. Moreover, its radioprotective effect was fully selective to normal tissues in RT models of solid tumors—T1023 reduced the severity of acute RSR and did not modify the antitumor effects of γ-radiation. The results indicate that T1023 can selectively protect the non-malignant tissues against γ-radiation due to hypoxic mechanism of action and potentiate opportunities of NOS inhibitors in RT complications prevention