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Procedures for purification of porcine colipase II (Gly6-Gly89) and for obtaining purified anti-colipase antibodies are described. The interactions between antibodies immobilized on an Ultrogel AcA 22 column and colipase were investigated and colipase radioimmunoassay carried out. The immobilized antibody-colipase binding was preserved in the presence of mixed micelles, lipase, or both when added to the elution mixture. Bound colipase maintained its capability of interacting with mixed micelles, but not with lipase in either the presence or the absence of mixed micelles. It could be inferred that the antigenic site(s) is independent of the interfacial recognition site and close to the site of lipase recognition. Results are reported suggesting that one or both colipase histidyl residue-containing sequences are involved as antigenic determinant(s). Immunoreactive colipase, bound to a macromolecular protein complex, was found in the plasma of pig. This finding could be explained by an endocrine 'leakage' of colipase from the exocrine pancreatic cell rather than by passage through the intestinal mucosa.

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The effects of gastrointestinal flora on the quantitative and qualitative aspects of "endogenous" fecal fatty acid excretion were studied in the rat using germ-free (GF) and conventional (CVL) animals, lipid-free diet and open-tubular gas-liquid chromatography. Gastrointestinal flora slightly increased endogenous excretion of fatty acids. Analysis of fatty acids from different fecal lipid fractions showed that the presence of a microflora in the gastrointestinal tract extensively modified the qualitative aspects of endogenous fecal fatty acid spectra. In total endogenous fecal lipids, concentrations of mono and polyunsaturated fatty acids (from C16 to C22) were 3.5 times higher in GF rats, while concentrations of even-numbered and saturated fatty acids were 1.5 times higher in CVL rats. Odd-numbered fatty acids (from C11:10 to C2:0) represented 6.5% of total endogenous fecal fatty acids in CVL rats vensus 1.5% in GF rats. Branched-chain fatty acid (even-and-odd-numbered, iso and anteiso) concentrations were 12.9% in CVL rats versus 2.0% in GF rats. Results clearly showed that the gastrointestinal flora was the main source of odd-numbered fatty acids and branched-chain fatty acids in endogenous fecal lipids. However, a secondary source may also exist since these fatty acids represented 3.5% of the total endogenous fatty acids in GF rats.

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Results presented in this study emphasize the long-term effects of dietary fatty acid chain length on some biochemical parameters of the liver in the growing rat. High levels of medium-chain fatty acids feeding (C8:O and C12:O) from 40 to 340 g of body weight induced liver growth and lipid contents intermediary between values recorded with a lipid-free diet and with a diet containing long-chain fatty acids. No steatosis was recorded but neutral lipid contents appeared to be correlated with the dietary fatty acid chain length while phospholipid contents remained much more stable. In the four tested nutritional conditions, only dodecanoïc or lauric acid (C12:O) feeding induced important alterations in the fatty acid pattern of liver neutral lipids. Medium-chain fatty acids, and even lauric acid which was intensely esterified in adipose tissue triglycerides, did not appreciably modify the fatty acid composition of liver phospholipids and were not esterified in it.

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During the growth (35 g-340 g), and as compared to results obtained with a lipid-free diet or a diet containing long-chain fatty acids, high levels of Tri C8 : O or Tri C12 : O did not change the quantitative aspects of proteinogenesis and lipogenesis balances. The incorporation of Tri C8 : O into the diet did not change the fatty acid composition of body lipid stores while the incorporation of Tri C12 : O induced a lipogenesis characterized by the disappearance of about 50% of the n-9 and n-7 unsaturated fatty acids, the emergence of an equivalent amount of saturated fatty acids in C12 and C14, and the decrease of hexadecanoic or palmitic acid concentration. Titers of saturated fatty acids with a melting point higher than 40 degrees C increased from 34% to 64%. Results suggested an efficient inhibition of fatty acid biosynthesis de novo by C12 : O, associated with an impossibility for microsomal enzymes to assume the elongation of a sufficient amount of C12 : O to maintain C16 : O concentration and to furnish an important amount of substrate (C18 : O) to delta-9-stearoyl coenzyme A desaturase for oleic acid synthesis. Introducing dodecanoic acid into the diet of growing animals appears to be the most efficient method for increasing the degree of saturation of body lipids without changing the concentrations of long-chain saturated fatty acids.

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1. Fatty-acid composition of hare milk triacylglycerols markedly differed from that of rabbit milk and was essentially characterized by a 2.1 times lower concentration of medium-chain fatty-acids (M.C.F.A.). 2. Consequently, very high levels (greater than 70 moles %) of M.C.F.A., previously reported for rabbit milk, cannot be considered as a general characteristic of the Leporidae. 3. General tendencies recorded for intramolecular fatty acid distribution in hare milk triacylglycerols agreed with those reported for other animal species.

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In the trout, the unsaturated fatty acids are preferentially located in the beta-position and the saturated fatty acids in the alpha-position of triglycerides. This fatty acid distribution is retained even with diets containing lard. The fish are, therefore, able to modify completely the fatty acid distribution of dietary triglycerides. There is no retention of the beta-monoglyceride structure during the biosynthetic processes. However, the modification of the dietary fatty acid distribution by the trout seems to be more difficult at 18C than at 10C.

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Dodecanoic or lauric acid (C 12 : 0) ingestion before and during lactation causes profound changes in the fatty-acid secretion by Rat mammary gland. Lauric acid concentration in milk lipids may reach 35% of total fatty-acids; saturated fatty-acids represent 80% of total secreted fatty-acids. When exogenous lauric acid supply is given, mammary tissue does not efficiently regulate the qualitative aspects of fatty-acid secretion.

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Lauric acid feeding induced large alterations in mammary gland fatty acid secretion. It was highly incorported in milk triglycerides, suggesting that mammary gland was not able to efficiently regulate the qualitative aspects of medium-chain fatty acid secretion. These modifications in milk fatty acid secretion did not alter pup growth, lipogenesis balance or the classic parameters of the pup liver during the suckling period. Nevertheless, maternal lauric acid feeding induced important alterations in the qualitative aspects of pup lipogenesis before weaning.

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1. The Michaelis constant (Km) of the trout pancreatic lipase is 1.3 x 10(-6) M tributyrin, calculated by the interface concentration of the emulsion. This value is lower than that of porcine pancreatic lipase. 2. The lipase hydrolyses tributyrin in a Ca2+ free medium. Conversely, Ca2+ is essential for the lipolysis of triolein. The cation might be an effector of the reaction, but it seems to remove the inhibition of the enzyme by its product. 3. The curves of the lipase activity according to bile salt concentration seem to suggest the existence of a colipase, that we have not evidenced yet by direct procedures. 4. The apparent molecular weight of the lipase seems to be lower in the trout than in the species studied so far.

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In the first part, the reasons for the choice of Carbowax 20M-terephthalic acid as a liquid phase are indicated and the technique for preparation of columns is descirbed. The ECL of 14 to 24 carbon fatty acids (branched and positional isomers of unsaturated acids) as well as the accuracy of determination of some fatty acids, are presented. In the second part, examples of chromatograms are given as well as tables concerning the composition of various fats: vegetable oils, depot fats, and fats from organs of monogastric species, polygastric species, and fish.

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In the growing rats weighting between 70 and 300 g, when 20% of the total daily energy intake consists either of 'lard (with 36% oleic acid) or sunflowerseed oil (with 61% linoleic acid)', lipogenesis, proteinogenesis, feed efficiency ratio and body compositions are identical. With the nutritional conditions used during these experiments, the occurrence of a high level of polyunsaturated fatty acids level in the diet cannot be considered as an exogenous factor able to modify the parameters studied.

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