Ticks acquire nutrients only by a parasitic nature of feeding on animals, including humans. During this process, a wide array of pathogens is transmitted. Ticks of the Ixodidae family receive exactly one blood meal in each active developmental. Knowing the trophic dependence of tick metabolism on the host blood meal components may enable discovering processes essential for the tick physiology and development. Exploiting a membrane system of tick feeding and whole blood fractionation, we have revealed that adult ticks need to acquire host haemoglobin-derived haem so that they can produce viable larvae, and reproduce. Haem is not further catabolised in ticks, and iron is thus acquired via independent route with the host serum transferrin as a source molecule. Using RNA-seq, we compared transcriptome compositions between guts of blood- and serum-fed ticks. We identified fifteen gut transcripts that change their levels with respect to the presence/absence of dietary red blood cells. Glutathione S-transferase, one of the identified encoded molecules, shows a clear haeminresponsive expression at both transcript and protein levels. Its apparent haem-binding properties suggest that this protein is directly involved in haem homeostasis maintenance within the tick gut. The ultimate goal of such research is to identify and verify targets that, when blocked, would render the acquisition and/or distribution system of haem in ticks nonfunctional. This would represent a novel way of anti-tick interventions in veterinary and human medicine.

Dans le vin, les amines biogènes sont essentiellement d'origine microbienne, et sont produitesnotamment par les bactéries lactiques Oenococcus oeni, principal agent responsable de lafermentation malolactique, possède de nombreuses auxotrophies vis-à-vis des acides aminés.Aucune étude n'a été menée sur la relation entre l’auxotrophie vis-à-vis d’un acide aminé et leniveau de l’amine correspondante. 80 souches de Oenococcus oeni ont été isolées de vinsrouges. Leurs auxotrophies vis-à-vis d’acides aminés précurseurs d’amines biogènes (Arg,Tyr, His et Phe) ainsi que la présence de gènes codant des enzymes impliquées dans lasynthèse des amines ont été étudiées. Aucune relation entre auxotrophie et niveau deproduction d’amines ne peut être établie pour les souches testées. La présence de gènes codantdes enzymes impliquées dans la synthèse d’amines n’est pas non plus corrélée avec laproduction effective d’amines. Nous montrons pour la première fois que Oenococcus oeni estun producteur d’agmatine. Cette production est étroitement liée à la souche bactérienne. Lasouche la plus adaptée au milieu acide est celle qui consomme le plus l’arginine et enproportions équivalentes par les 2 voies : voie de l’arginine déiminase et voie de l’argininedécarboxylase. L’effet d’une addition d’agmatine dans des vins montre une atténuation del’effet boisé du Chardonnay sans doute par formation de base de Schiff ente les composésd’arôme et cette amine / In wine biogenic amines (BA) are mainly of microbial origin, Oenococcus oeni, the mainresponsible for malolactic fermentation, has been identified as a BA producer from nitrogenprecursors. Oenococcus oeni possess numerous amino acid auxotrophies that are precursors ofbiogenic amines. No study has been done so far to look at the relationship betweenauxotrophy for amino acids precursors of BA and the level of BA in the medium. In order todo so, 80 Oenococcus oeni strains were isolated from red wines. The detection of genesencoding the different decarboxylases responsible for BA synthesis has been realised. Inparallel, the auxotrophy for the four amino acids (Arg, Tyr, His, Phe) precursors of BA hascharacterized. Our results demonstrate that there is not direct correlation between auxotrophyand the accumulation of the corresponding BA as well as between the presence ofdecarboxylase gene and the accumulation of the corresponding BA. High levels of agmatineproduced from arginine decarboxylation by Oenococcus oeni is reported for the first time.Agmatine production is strain dependant. the most adapted to acidic environment is the strainwhith use arginine in higher level with same proportion for ADI pathway and argininedecarboxylase. Agmatine addition in wines reduce woody aroma probably by formation ofsciff bases between aromla compounds and amine