The toxicokinetics of the food and feed contaminant Fumonisin B (FB) are characterized by low oral absorption and rapid plasma elimination. For these reasons, FB is not considered to accumulate in animals. However, recent studies in chicken and turkey showed that, in these species, the hepatic half-elimination time of fumonisin B1 (FB1) was several days, suggesting that FB1 may accumulate in the body. For the present study, 21-day-old chickens received a non-toxic dose of around 20 mg FB1 + FB2/kg of feed to investigate whether FB can accumulate in the body over time. Measurements taken after four and nine days of exposure revealed increased concentrations of sphinganine (Sa) and sphingosine (So) over time in the liver, but no sign of toxicity and no effect on performances were observed at this level of FB in feed. Measurements of FB in tissues showed that FB1 accumulated in chicken livers from four to nine days, with concentrations of 20.3 and 32.1 ng FB1/g observed, respectively, at these two exposure periods. Fumonisin B2 (FB2) also accumulated in the liver, from 0.79 ng/g at four days to 1.38 ng/g at nine days. Although the concentrations of FB found in the muscles was very low, an accumulation of FB1 over time was observed in this tissue, with concentrations of 0.036 and 0.072 ng FB1/g being measured after four and nine days of exposure, respectively. Feeding algo-clay to the chickens reduced the accumulation of FB1 in the liver and muscle by , approximately 40 and 50% on day nine, respectively. By contrast, only a weak non-significant effect was observed on day four. The decrease in the concentration of FB observed in tissues of chickens fed FB plus algo-clay on day nine was accompanied by a decrease in Sa and So contents in the liver compared to the levels of Sa and So measured in chickens fed FB alone. FB1 in the liver and Sa or So contents were correlated in liver tissue, confirming that both FB1 and Sa are suitable biomarkers of FB exposure in chickens. Further studies are necessary to determine whether FB can accumulate at higher levels in chicken tissues with an increase in the time of exposure and in the age of the animals.

Fumonisins (FB) are mycotoxins known to exert most of their toxicity by blocking ceramide synthase, resulting in disruption of sphingolipid metabolism. Although the effects of FB on sphinganine (Sa) and sphingosine (So) are well documented in poultry, little information is available on their other effects on sphingolipids. The objective of this study was to analyze the effects of FB on the hepatic and plasma sphingolipidome in chickens. The first concern of this analysis was to clarify the effects of FB on hepatic sphingolipid levels, whose variations can lead to numerous toxic manifestations. The second was to specify the possible use of an alteration of the sphingolipidome as a biomarker of exposure to FB, in addition to the measurement of the Sa:So ratio already widely used. For this purpose, we developed an UHPLC MS/MS method that enabled the determination of 82 SL, including 10 internal standards, in chicken liver and plasma. The validated method was used to measure the effects of FB administered to chickens at a dose close to 20 mg FB1 + FB2/kg feed for 9 days. Significant alterations of sphingoid bases, ceramides, dihydroceramides, glycosylceramides, sphingomyelins and dihydrosphingomyelins were observed in the liver. In addition, significant increases in plasma sphinganine 1-phosphate, sphingosine 1-phosphate and sphingomyelins were observed in plasma. Interestingly, partial least-squares discriminant analysis of 11 SL in plasma made it possible to discriminate exposed chickens from control chickens, whereas analysis of Sa and So alone revealed no difference. In conclusion, our results show that the effects of FB in chickens are complex, and that SL profiling enables the detection of exposure to FB when Sa and So fail.

Most of the toxic effects of fumonisins can be related to sphingolipid alteration, but there is little sphingolipidomic data in animals fed fumonisins in organs other than the liver. This study aimed to measure fumonisin B1 (FB1) in kidney, lung, and brain and determine its effects on sphingolipids. Thirty chickens divided into three groups received a diet containing 20.8 mg FB1+FB2/kg for 0, 4, or 9 days. FB1 increased in kidney from 1.7 to 5.6 nmol/kg and in lung from 0.5 to 1 nmol/kg at 4 and 9 days, respectively. No FB1 was detected in brain. In kidney, sphinganine increased, C14-C16 ceramides decreased, whereas C18-C26 ceramides increased. Most of the changes in dihydroceramides, dihydrodeoxyceramides, deoxyceramides sphingomyelins, dihydrosphingomyelins, and hexosylceramides paralleled those on ceramides. In lung, sphinganine was unaffected by fumonisins, whereas sphinganine-1-phosphate increased. Other major changes corresponded to decreases in glycosylceramides. In brain, sphinganine was unchanged, whereas deoxysphinganine, sphingosine, C14-C20 ceramides, and C14-C20 sphingomyelins increased. These results revealed that alterations in sphingolipids in kidney were close to those measured in liver and could correspond to inhibition of ceramide synthase 5 activity. In contrast, effects of fumonisins in lung and brain cannot be explained by inhibition of ceramide synthase.

Alteration of sphingolipid synthesis is a key event in fumonisins toxicity, but only limited data have been reported regarding the effects of fumonisins on the sphingolipidome. Recent studies in chickens found that the changes in sphingolipids in liver, kidney, lung, and brain differed greatly. This study aimed to determine the effects of fumonisins on sphingolipids in heart, gizzard, and breast muscle in chickens fed 20.8 mg FB1 + FB2/kg for 9 days. A significant increase in the sphinganine:sphingosine ratio due to an increase in sphinganine was observed in heart and gizzard. Dihydroceramides and ceramides increased in the hearts of chickens fed fumonisins, but decreased in the gizzard. The dihydrosphingomyelin, sphingomyelin, and glycosylceramide concentrations paralleled those of ceramides, although the effects were less pronounced. In the heart, sphingolipids with fatty acid chain lengths of 20 to 26 carbons were more affected than those with 14–16 carbons; this difference was not observed in the gizzard. Partial least squares-discriminant analysis on sphingolipids in the heart allowed chickens to be divided into two distinct groups according to their diet. The same was the case for the gizzard. Pearson coefficients of correlation among all the sphingolipids assayed revealed strong positive correlations in the hearts of chickens fed fumonisins compared to chickens fed a control diet, as well as compared to gizzard, irrespective of the diet fed. By contrast, no effect of fumonisins was observed on sphingolipids in breast muscle.

The current control of gastrointestinal (GI) parasitic nematodes mainly relies on the widespread use of anthelmintics, which has inevitably led to resistance. Therefore, there is an urgent need to find new sources of antiparasitic compounds. Macroalgae represent a rich source of active molecules and are widely described as having medicinal properties. In the present study, we investigated the potential anthelmintic activity of aqueous extracts from three species of algae (Bifurcaria bifurcata, Grateloupia turuturu and Osmundea pinnatifida) on the murine parasite Heligmosomoides polygyrus bakeri. Using a set of complementary in vitro tests, including larval development assays, egg hatching tests and nematicidal activity assays on larvae and adults, we report the nematicidal activity of aqueous extracts of B. bifurcata. In addition, aqueous extract fractionation using liquid/liquid partitioning with a solvent of increasing polarity was performed in order to identify the groups of active molecules underlying the anthelmintic activity. Non-polar extracts (heptane, ethyl acetate) demonstrated high anthelmintic potential, highlighting the role of non-polar metabolites such as terpenes. Here, we highlight the strong anthelmintic potential of the brown alga B. bifurcata on a mouse model of GI parasites, thus confirming the strong interest in algae as natural alternatives for the control of parasitic nematodes.

Les polysaccharides algaux sont une ressource marine dont la valorisation est limitée par le manque d’outils adéquats à leur modification chimique. Grâce aux enzymes qu’elles synthétisent, les bactéries marines, qui vivent au contact des algues, représentent un enjeu majeur pour le développement des biotechnologies bleues. Cette thèse a permis de cloner et d’obtenir sous forme soluble plusieurs dizaines de nouvelles enzymes bactériennes marines actives sur des polysaccharides algaux. Quatre d’entre elles ont fait l’objet d’une étude plus spécifique. Les deux premières sont impliquées dans les voies de dégradation des carraghénanes. La première, ZgCgkA, est une κ-carraghénase de la famille 16 des glycosides hydrolases (GH), synthétisée par la bactérie Zobellia galactanivorans. Son étude biochimique et structurale, par cristallographie des rayons X, a permis de corréler certaines différences structurales à des modes d’interaction différents avec le substrat, au sein de cette sous-famille des GH16. La seconde enzyme étudiée, une β-carrabiose hydrolase de Pseudoalteromonas carrageenovora, agit sur des oligosaccharides hybrides β/κ. Son étude biochimique et phylogénétique a permis de proposer la création d’une nouvelle famille de GH apparentée aux GH42. Enfin, les deux dernières enzymes étudiées, une GH29 et une GH non-classée, sont codées dans un locus de Z. galactanivorans qui semble impliqué dans la dégradation de substrats enrichis en fucose sulfaté. La GH29 a fait l’objet d’une caractérisation biochimique sur substrat synthétique, et son analyse structurale est en cours. Ces différents résultats permettent d’envisager l’utilisation de ces enzymes comme outils de valorisation des polysaccharides algaux, en particulier des carraghénanes.