Annales de la nutrition et de l'alimentation最新文献

Higher plants synthesize large amounts of linoleic and alpha-linolenic acids by progressive desaturation of oleic acid. Plant desaturases are active only during a short period of the development of seeds or leaves. 14C-oleate desaturation has been followed experimentally in various plants (Rapeseed, Sunflower, Flax and Potato). With aged potato slices, it has been shown that oleate-desaturase is an inducible enzymatic system. With microsomes isolated from aged potato-slices, 14C-oleoyl-CoA has been desaturated in vitro. Recent results suggest that oleoyl-phosphatidylcholine is the true substrate of the desaturation system. The formation of the alpha-linolenic acid of chloroplasts has not been obtained in vitro, up to now. In vivo, the newly formed linolenic acid is found in chloroplast galactolipids. In conclusion, difference between animal and plant desaturases are underlined.

Extraction of oyster lipids were carried out on total wet organic tissues with a mixture of chloroform-methanol. The different fractions of polar and not polar lipids were separated by thin layer chromatography (TLC) and the methyl esters of the constituant fatty acids has been prepared by transmethylation a cold for use in subsequent gas-liquid chromatography (open tubular gas chromatography). The oyster contained considerable proportions of C16:0 and heiglhly unsaturated acids (specially in lecithin and cephalin) of C20, C22 series which are characteristic of the lipids of most acquatic plants and animals. Studies were made of the seasonal variations.

In the course of the foetal development of numerous animal species elevated serum concentrations of alpha-1-foetoprotein (AFP) are observed. The level of this foetal protein decreases after birth, but reappears in several pathological cases characterized by a cellular proliferation, in particular in neoplasia such as hepatoma and teratoblastoma. Little was known until 1971 on the biological role of this carcino-embryonic antigen. It has been since evidenced [Nunez and al., 1971, C.R. Acad. Sci., Paris, 273, 834-841]. That rat and mouse AFPs bind oestrogens with high affinity (Ka = 10(8) M-1) [Savu and al., 1972, F.E.B.S. Let., 22, 113-116]. Human AFP does not possess this property. We have recently shown [Benassayag and al., 1977, Steroids, 30, 771-785] that the sera from pregnant rats, rat and human foetuses contain compounds which behave as competitive inhibitors of the estrogen binding on rat or mouse AFP. We have subsequently identified this substances as a mixture of non-esterified fatty acids (NEFA) [Vallette and al., XXVII Colloquium "Protides of the biological fluids", Bruxelles, H. Peeters Ed., Pergamon Presse, 1979]. We have measured [BENASSAYAG and al., Oncodevelopmental biology and medicine, in press] the association constants of each NEFA of the serum mixture with rat AFP, the polyunsaturated fatty acids (PUFA) (C 20:4, C 22:4, C 22:6) show the highest association constants (Ka = 10(5)-10(6) M-1). We have also confirmed that human AFP binds the PUFA with high affinity. The biological perspectives opened up by these novel data will be discussed.

Studies on the survival, fecundity, and food consumption by M. persicae reared on synthetic diets, have indicated: --gentisic and oxalic acids have a deleterious effect as most important as their dose is high. --succinic acid reduces, at least for the used concentrations, the deleterious effect of the oxalic acid, but not that of the gentisic acid. --gentisic acid is quickly decreasing food consumption. --the deleterious effect of oxalic and gentisic acids is not decreasing with time. The results are discussed in regard with the plant-aphid relations.

Nitrate accumulation in the plant represents the difference between nitrate absorption and their use. The absorption depends essentially on the available nitrate supply to the plant. We can distinguish two sources of nitric nutrition: mineral nitrogen fertilising of the crop under consideration, and mineralization of the soil organic nitrogen. While the former is directly dependent on us, the latter can hardly be controlled in terms of quantity as well as timing of the supply. On the basis of an example it is shown that the latter source of supply, as compared to mineral nitrogen fertilizing, sometimes leads to an abnormal accumulation of nitrates when the time of supply (mineralization) is not in conformity with the crop requirements during the corresponding period. The use of nitrates obviously depends on the specific physiology and the conditions affecting plant nutrition. We think that nitrate accumulation in the leaves is linked to the relative importance of nitrate metabolism in the roots and in the leaves. The tendency of various plant component to accumulate nitrates is also discussed on the basis of a few examples.

With the exception of some cell strains in culture, the animal cells need w6 linoleic acid and its superior polyinsaturated derivatives for their structural growth and their multiplication. Deficiency of linoleic acid leads to growth failure, organic fraility and death of the animal. Involvement of the prostaglandins is not demonstrated. w3 linolenic acid and its superior derivatives are essential for the development of the sea animals. Linolenic acid appears also essential for the mammal nervous cells at the step of cell division anterior to myelinisation. Disponibility of the essential fatty acids for the mammal fetus is principaly assumed by the mother liver of which the metabolic activity in conversion of the precursors to superior derivatives and synthesis of transport lipoproteins is increased. Involvement of the polyunsatured acids in satisfying the structural and energetic needs of the developing animal concerns predominantly--but not exclusively--the cell membranes structure and fluidity and activity of the functional proteins (enzymes, mitochondrial oxydophosphorylation).

The aim of this study is to search for small underground side basins in order to propose them to agricultural businessmen. Those basins should be apt to a successful experiment of cultural techniques to reduce nitrogen leakages toward aquifers. They should allow to identify and try to quantify the reasons of nitrogen enrichment of the underground waters by a critical examination of the past of some reappearances and the use of their recharge basin. This work consisted, after drawing up evolution graphs of nitrate rates, in selecting springs at first according to their interannual variations amplitude with increasing nitrogen rates, secondly according to their moderate flow-having unimportant side basins and thin storage aquifer and therefore reacting rapidly to the surface attraction. Finally, the springs were selected according to their specified pollution so that the collected water should be a representative sample of the aquifer. Eleven spots were thus selected. We hope they will allow to draw an experiment over the 3 or 5 next years.