L’huître du pacifique Crassostrea gigas est l'espèce marine la plus cultivée avec une production supérieure à 4 millions de tonnes pour l'année 2010. En France, C. gigas est cultivée depuis la fin des années 1970. Cependant, cette espèce souffre d’un syndrome de mortalité estivale depuis les années 1980, avec une amplification depuis 2008 qui touche jusqu'à 100 % des naissains. Ce syndrome de mortalité est un phénomène multifactoriel, basé sur l’interaction de nombreux facteurs: stress environnementaux, caractéristiques physiologiques et génétiques de l’huître, présence et virulence de pathogènes. L’huître du pacifique C. gigas est une espèce estuarienne qui est soumise aux pressions anthropiques comme la pollution du milieu côtier. Ces événements représentent des sources potentielles de stress en zones ostréicoles. Cependant, les connaissances sur les effets des polluants comme les pesticides sur C. gigas restent fragmentaires. Les périodes d’épandage d’herbicides coïncident parfois avec la période de reproduction des huîtres, raison pour laquelle nous considérons que ces produits chimiques pourraient affecter la génération suivante d'huîtres. Parmi les pesticides, le diuron est le plus fréquemment détecté sur les côtes françaises, avec une concentration maximale rapportée de 0,78 µgL-1. L'exposition directe aux herbicides affecte le transcriptome des huîtres qui est le premier niveau de réponse face à l'exposition du polluant. Il a été démontré que l'exposition parentale au diuron a des effets génotoxiques chez C. gigas au stade de naissain. Une variabilité phénotypique de trait d’ histoire de vie a été observée aussi pour ces naissains. Un autre effet possible des pesticides serait la modification de marques épigénétiques. Il est connu que les facteurs environnementaux telle que la pollution par des composés chimiques peuvent modifier l'épigénome et par conséquent le phénotype des individus et de leurs descendance en agissant au niveau trans-générationnel. Ces dernières observations nous permettent d’émettre l’hypothèse de l’implication de mécanismes épigénétiques suite à l’interaction avec des produits phytosanitaires. Ces mécanismes modifieraient le phénotype des huîtres au stade de naissains par l'exposition parental. Pour tester cette hypothèse nous avons étudié la méthylation globale de l'ADN (méthylome), qui est un de principal marques épigénétiques, et le transcriptome des naissains issus de géniteurs exposé au Diuron. Nous avons identifié des modifications du méthylome et du transcriptome qui ont un lien avec le phénotype de trait d'histoire de vie de ces naissains. Ces résultats démontreraient qu’une exposition indirecte ou parentale du diuron modifie la méthylation et l'expression de fonctions de gènes spécifiques, expliquant en partie la variabilité phénotypique observée. / The Pacific Oyster Crassostrea gigas is the most cultivated marine species in the world with a production superior to 4 millions of tons in 2010. In France, C. gigas is cultivated since the end of 1970s. However, this specie suffers from a syndrome of summer mortalities since the 1980s, with an amplification since 2008 affecting up to 100% of spats. This syndrome of mortality is a multifactorial phenomenon, based on the interaction of many factors: Environmental factors, genetic and physiologic features of the oysters, and the presence and virulence of pathogens. The Pacific Oyster C. gigas is an estuarine specie which is subjected to anthropogenic pressures such as pollution of the coastal environment. These events represent a potencial source of stress in oyster farm areas. However, the knowledge about the effects of pollutants such as pesticides on C. gigas remain fragmented. The herbicide application periods may coincide with the oyster breeding period, reason for which we consider that these chemicals could affect the next generation of oysters. Among pesticides, diuron is the most frequently detected on the French coast, with a maximum reported concentration of 0.78 µgL-1.The direct exposure to herbicides affects the transcriptome of oysters which is the first level of response to the exposure of pollutants. It was shown that parental exposure to diuron has genotoxic effects on C. gigas at the spat stage. A phenotypic variability of life history traits has also been observed for these spats. Another possible effect of pesticides would be the modification of epigenetic marks. It is known that environmental factors such as pollution by chemical compounds can alter the epigenome and consequently the phenotype of individuals and of their offspring acting at a transgenerational level. These last observations allow us to hypothesize the involvement of epigenetic mechanisms in response to interactions with herbicide products. These mechanisms could modify the phenotype of oysters spat state by parental exposure. To test this hypothesis we studied the genome-wide DNA methylation (methylome), which is a main epigenetic mark, and the transcriptome of the spat from diuron-exposed genitors. We identified methylome and transcriptome changes that are related to the phenotype of life history trait of these spats. These results show that an indirect or parental exposure to the diuron is able to modify the methylation and the expression of specific gene functions, partially explaining the phenotypic variability observed.

O consumo de moluscos bivalves pode representar sérios riscos à saúde pública, pois refletem diretamente as condições do meio ambiente. Desta forma considera-se de extrema importância o consumo de mexilhões livres de contaminação. Esta pesquisa objetivou estudar a qualidade microbiológica das águas e mexilhões de três pontos de cultivo do município de Ubatuba, SP, a saber: Engenho da Almada, Barra Seca e Costão do Cedro em um período compreendido entre novembro de 2002 e março de 2003, totalizando 5 coletas mensais. Analisou-se na água: Bacillus cereus, Clostrídios Sulfito Redutores, Aeróbios Mesófilos, Staphylococcus aureus, Coliformes totais e fecais, Enterococos e Salmonella. Nos mexilhões foram analisados os mesmos microrganismos citados para água mais o Clostridium perfringens. Os resultados encontrados tanto para as análises de água como dos mexilhões foram satisfatórios, condizentes com a legislação brasileira em vigor, salvo a coleta do mês de março, do cultivo da Barra Seca, onde a média dos valores encontrados para coliformes fecais na água (5,7x101 NMP/100mL) foi superior ao recomendado pela legislação sendo detectado também neste mesmo cultivo e mês, presença de Salmonella em 25 g nas amostras de mexilhões. Mesmo que as contagens de S. aureus e B. cereus na carne estejam de acordo com a legislação em vigor, cuidados devem ser tomados quanto ao armazenamento e a forma de consumo. Averiguou-se a intensidade de interferências sazonais na contagem microbiana na água e constatou-se que a tábua de marés e o índice de insolação diária tiveram uma correlação negativa baixa, ao contrário do índice pluviométrico que apresentou correlação positiva alta. / The consumption of bivalve mollusks can represent serious risks to the public health, because they reflect the conditions of the environment directly. This way it is considered of extreme importance the consumption of mussels without contamination. This work aims of studing the water and mussels microbiology quality from three different seafood farms in Ubatuba, SP, to know: Engenho da Almada, Barra Seca and Costão do Cedro from November 2002 to March 2003, totaling five monthly. It was analyzed in the water: Bacillus cereus, Total Clostridia, Aerobic Mesophilic, Staphylococcus aureus, total and fecal coliforms, Enterococci and Salmonella. In the mussels the same microorganisms were analyzed mentioned for water more Clostridium perfringens. The results found in the water and in the mussels were satisfactory, suitable with the Brazilian legislation, except for the sample at Barra Seca’s beach, in March. The average of the values found at that place for fecal coliformes in the water was higher (5,7x101 MPN/100mL) than the recommended by the legislation. Even in this collection, it was also detected Salmonella in 25 g of mussels. Even if the counts of S. aureus and B. cereus in the mussesls are in agreement with the legislation in vigor cares they should be taken with relationship to the storage and the consumption form. The intensity of seasonal interferences was discovered in the microbial count in the water, in which was verified that the board of tides and the index of daily heatstroke had a low negative correlation unlike the index pluviometric it presented high positive correlation

O consumo de moluscos bivalves pode representar sérios riscos à saúde pública, pois refletem diretamente as condições do meio ambiente. Desta forma considera-se de extrema importância o consumo de mexilhões livres de contaminação. Esta pesquisa objetivou estudar a qualidade microbiológica das águas e mexilhões de três pontos de cultivo do município de Ubatuba, SP, a saber: Engenho da Almada, Barra Seca e Costão do Cedro em um período compreendido entre novembro de 2002 e março de 2003, totalizando 5 coletas mensais. Analisou-se na água: Bacillus cereus, Clostrídios Sulfito Redutores, Aeróbios Mesófilos, Staphylococcus aureus, Coliformes totais e fecais, Enterococos e Salmonella. Nos mexilhões foram analisados os mesmos microrganismos citados para água mais o Clostridium perfringens. Os resultados encontrados tanto para as análises de água como dos mexilhões foram satisfatórios, condizentes com a legislação brasileira em vigor, salvo a coleta do mês de março, do cultivo da Barra Seca, onde a média dos valores encontrados para coliformes fecais na água (5,7x101 NMP/100mL) foi superior ao recomendado pela legislação sendo detectado também neste mesmo cultivo e mês, presença de Salmonella em 25 g nas amostras de mexilhões. Mesmo que as contagens de S. aureus e B. cereus na carne estejam de acordo com a legislação em vigor, cuidados devem ser tomados quanto ao armazenamento e a forma de consumo. Averiguou-se a intensidade de interferências sazonais na contagem microbiana na água e constatou-se que a tábua de marés e o índice de insolação diária tiveram uma correlação negativa baixa, ao contrário do índice pluviométrico que apresentou correlação positiva alta. / The consumption of bivalve mollusks can represent serious risks to the public health, because they reflect the conditions of the environment directly. This way it is considered of extreme importance the consumption of mussels without contamination. This work aims of studing the water and mussels microbiology quality from three different seafood farms in Ubatuba, SP, to know: Engenho da Almada, Barra Seca and Costão do Cedro from November 2002 to March 2003, totaling five monthly. It was analyzed in the water: Bacillus cereus, Total Clostridia, Aerobic Mesophilic, Staphylococcus aureus, total and fecal coliforms, Enterococci and Salmonella. In the mussels the same microorganisms were analyzed mentioned for water more Clostridium perfringens. The results found in the water and in the mussels were satisfactory, suitable with the Brazilian legislation, except for the sample at Barra Seca’s beach, in March. The average of the values found at that place for fecal coliformes in the water was higher (5,7x101 MPN/100mL) than the recommended by the legislation. Even in this collection, it was also detected Salmonella in 25 g of mussels. Even if the counts of S. aureus and B. cereus in the mussesls are in agreement with the legislation in vigor cares they should be taken with relationship to the storage and the consumption form. The intensity of seasonal interferences was discovered in the microbial count in the water, in which was verified that the board of tides and the index of daily heatstroke had a low negative correlation unlike the index pluviometric it presented high positive correlation