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Abstract: Over the two last decades, isolation and characterization of proteins involved in transport and metabolic fate of long-chain fatty acids have provided new insights on the molecular basis of fat absorption. This systematic cloning period has been followed by the functional genomics time which led to surprises. Indeed, disruption of several genes, thought to be crucial for long-chain fatty acid absorption, did not lead to clear phenotypes. This observation raises the question about the real physiological role of several lipid-binding proteins and enzymes found in the enterocyte. This mini-review assesses the present knowledge concerning the main steps of intestinal fat absorption: the cellular uptake and trafficking of long-chain fatty acids and the lipoprotein synthesis. [Copyright &y& Elsevier]

Abstract: Treatment of rape seedlings with increasing CdCl2 concentrations in the culture medium resulted in a cadmium accumulation within plant tissues, which increased with external metal dose; such accumulation was more important in roots than in leaves. Biomass production was severely inhibited, even at low cadmium concentration. In leaves, quantities of chloroplastic lipids, monogalactosyldiacylglycerol (MGDG), digalactosyldiacylglycerol (DGDG), sulfolipids (SL) and phosphatidylglycerol (PG) decreased sharply under metallic treatment. However, contents of extrachloroplastic lipids, mainly phosphatidylcholine (PC) and phosphatidylethanolamine (PE) increased significantly. In contrast to leaves, contents of root phospholipids decreased. Likewise, levels of tri-unsaturated fatty acids: linolenic (C18:3) and hexadecatrienoïc (C16:3) dropped in leaves of treated seedlings as compared to those of controls, suggesting that heavy metals induced an alteration in the fatty acid desaturation process or a stimulation of their peroxidation. Also, trans palmitoleic acid (C16:1-trans) level in PG decreased considerably. In roots, there was a slight decrease in C18:3 level, with a concomitant increase in the C18:2 percentage. Radioactive labelling of leaf lipids with (1-14C) acetate allowed to show that fatty acid biosynthesis was noticeably altered at the highest cadmium dose used (50 μM). Biosynthesis of tri-unsaturated fatty acids was also inhibited which may explain the decline in non-labelled lipid contents. Results showed that metallic ion seems to affect selectively chloroplastic membranes due to an inhibition of polyunsaturated fatty acid biosynthesis. Moreover, a lipid peroxidation occurred in our case because of the spectacular increase of malondialdehyde (MDA) content observed in cadmium treated leaves. To cite this article: N. Ben Youssef et al., C. R. Biologies 328 (2005). [Copyright &y& Elsevier]

Abstract: Aim. – This study aimed at defining how many fats require sportsmen with a high volume of training. Materials and method. – Nineteen ultra athletes and cyclists volunteered to take part. We assessed lipid intake with a 4-day dietary recall and a frequency questionnaire, in order to have a more precise quantification as possible. Results. – Our results showed first that in spite of a mean fat intake of 1.5 g/kg per day, eighteen out of our nineteen subjects presented with a biological abnormality, most of which concerned “omega 3” fats. Dietary recall did not help predicting any deficiency, except for “omega 3”. Every time rapeseed oil was not consumed, biological abnormalities were seen. Moreover, a carbohydrate intake below 6 g/kg per day increased the probability for a subject to have his biological fatty acids status being disturbed. Conclusion. – We concluded that “safety fat intakes” must be increased to 1.3 g/kg per day and that a high quality is required for fats. When rapeseed oil is lacking, “omega 3” requirements are harder to meet, even with fats intake far beyond 1,5 g/kg per day. Moreover, an optimal carbohydrate intake is necessary in order to meet fats requirements. [Copyright &y& Elsevier]

Circulating phospholipids carrying a single esterified fatty acid, the so-called lysophospholipids, are now considered as mediators of the intercellular communication. Their major members are the lysophosphatidic acid and the sphingosine 1-phosphate, two molecules displaying biological activities similar to those of growth factors or cytokines, through a recently identified subfamily of G protein-coupled receptors. They are involved in various biological processes, e.g., brain development and angiogenesis, but the following evidences suggest that these lipids are also significant actors of tumour development: (i) they stimulate the growth, survival and migration of tumour cells from various origins (ovary, prostate, glioblastoma…); (ii) they are abundant in malignant effusions; (iii) the lysophospholipid-producing enzymes are tumourigenic. Even if it remains necessary to define the role of these “oncolipids” in relationship with oncogenes and tumor suppressors, they may well be the mediators of an efficient autostimulatory system of the proliferating and migratory capacities of cancer cells, suggesting that lysophospholipids could represent novel valuable targets for anticancer pharmacology. [Copyright &y& Elsevier]

Lipids are the essential components of cell membranes and lipoproteins. Their peroxidation plays an important role in numerous pathologies in which oxidative stress is involved. Lipid peroxidation occurs through a chain reaction that contributes to membrane damage in cells. It results in the conversion of fatty acids to polar hydroperoxides and leads to the breakdown or malfunction of the membrane. Lipids are amphiphilic molecules that aggregate in aqueous solutions into micelles and liposoms. The effect of this structural organization is significant in studies of radiation-induced peroxidation damage in highly ordered biological systems such as biological membranes. In this paper, a synthesis of the data concerning radioinduced lipid peroxidation is completed by an original review of the different parameters that determine lipid oxidizability. In addition, the influence of lipid aggregation and the effect of molecular packing are discussed.Key words: radiolysis, peroxidation, lipids, fatty acids.Les lipides sont les constituants essentiels des membranes cellulaires et des lipoprotéines. Leur peroxydation est un processus qui intervient dans certaines pathologies dans lesquelles le stress oxydant est impliqué. La peroxydation lipidique est un mécanisme en chaîne de dégradation des acides gras membranaires conduisant à la formation d'hydroperoxydes instables, responsables néanmoins de la diminution de la fluidité membranaire. Les lipides sont des molécules amphiphiles qui s'agrègent en solution aqueuse sous forme de micelles ou de liposomes, structures organisées susceptibles de mimer, in vitro, les membranes biologiques. Dans cet article, une synthèse des données concernant la peroxydation lipidique radioinduite est complétée par une revue originale des différents paramètres déterminant l'oxydabilité des lipides; de même, l'influence de l'agrégation des lipides et du packing moléculaire y est commentée.Mots clés : radiolyse, peroxydation, lipides, acides gras. [ABSTRACT FROM AUTHOR]