Absence Of Fatty Acids Research Articles

Preparation and Evaluation of Eudragit Gels. VIII. Rectal Absorption of 5-Fluorouracil from Eudispert hv Gels in Rats

Rectal absorption of the hydrophilic 5‐fluorouracil (5‐FU) in rats was studied with Eudispert hv gels with or without fatty acids as the rectal bases. In the absence of fatty acids, absolute bioavailabilities of 5‐FU for Eudispert hv hydrogel and xerogel preparations increased ˜2.5 times compared with those of Witepsol H‐15 and PEG 2000 suppositories. Whenn‐capric acid or linolenic acid was used as an absorption enhancer, absolute bioavalabilities of 5‐FU were, respectively, 25.5 and 30.9% for Witepsol H‐15 and 64.4 and 66.1% for PEG 2000. Furthermore, the absolute bioavailabilities of 5‐FU for Eudispert hv hydrogel withn‐capric acid or linolenic acid were 95.6% and 81.7%. The addition of capric acid or linolenic acid to the hydrogel was a useful method for increasing 5‐FU permeability through the rectal membranes. These results are consistent with the observation that the total amounts of 5‐FU remaining in the lumenal contents of the rectum and that accumulated in the rectal tissue decreased in relation to the increase in the bioavailabilities. Thus, the Eudispert hv hydrogel containing 5‐FU with capric acid may be a useful rectal preparation for increasing the maximum plasma level and improving the absolute bioavailability of 5‐FU.

Fatty acid binding to bovine serum albumin prevents formation of intermediate during denaturation.

Urea-induced denaturation of defatted BSA and BSA containing six mol palmitic acid/mol protein (fatted BSA) has been studied by the techniques of UV difference spectroscopy and fluorescence spectroscopy. The notable differences between the two transitions are a shift in the transition of fatted BSA to a higher urea concentration and a three-state denaturation transition in defatted BSA compared to an apparent two-state denaturation transition in fatted BSA. The stable denaturation intermediate in defatted BSA occurs at 4.5-5.0 M urea, a urea concentration at which denaturation in fatted BSA has not yet started. These results are further supported by the difference spectral results obtained at 4.5 M urea in the two albumin preparations. The occurrence of denaturation intermediate only in defatted BSA and the presence of the two strong fatty-acid-binding sites in domain III lead us to conclude that this domain is relatively unstable in the absence of fatty acids and is responsible for the formation of intermediate.

Ascorbate Indirectly Stimulates Fatty Acid Utilization in Primary Cultured Guinea Pig Hepatocytes by Enhancing Carnitine Synthesis

L-Ascorbic acid is required for the synthesis of L-carnitine, which is essential for the oxidation of long-chain fatty acids. The purpose of this study was to investigate the role of ascorbate on the oxidation of long-chain fatty acids in primary cultured guinea pig hepatocytes. The hepatocytes were incubated in medium containing carnitine in the presence or absence of fatty acids. Exogenous fatty acids had no influence on the uptake of total carnitine into cells, but they lowered the free carnitine and consequently raised the concentration of short-chain acyl carnitine. Furthermore, carnitine supplementation of the medium in the presence of fatty acids led to a decrease of triglycerides in cells and an increase in the secretion of beta-hydroxybutyrate. These changes were also induced by the supplementation of the medium with both ascorbate and the precursor of carnitine (gamma-butyrobetaine) in the presence of fatty acids, although either ascorbate of gamma-butyrobetaine alone had no effect. In addition, increasing the concentration of supplemental ascorbate resulted in an enhancement of ketogenesis and a decrease of triglyceride accumulation. These results suggest that ascorbate enhances carnitine synthesis, which in turn stimulates beta-oxidation of fatty acids.

Differences in myocardial ischemic tolerance between 1- and 7-day-old rabbits.

Between 1 and 7 days of life, the newborn rabbit heart shifts from predominantly using carbohydrates to predominantly using fatty acids as an energy substrate. We therefore used isolated working hearts from 1- or 7-day-old rabbits to determine the effects of fatty acids on myocardial glucose use and the ability of hearts to recover following various periods of transient no-flow ischemia. One-day-old hearts were perfused via the inferior vena cava and ejected buffer through the cannulated aorta and pulmonary artery. Seven-day-old hearts were perfused via the left atrium and ejected buffer through the cannulated aorta. To measure glucose use, hearts were perfused with 11 mM [3H, 14C]glucose, 3% albumin, and 500 microU insulin/mL, in the presence or absence of 0.4 mM palmitate. In the absence of fatty acids, glycolytic rates were similar in 1- and 7-day-old hearts, whereas glucose oxidation rates were 5 times greater in 7-day-old hearts. Palmitate did not have any major effects on overall glucose use in 1-day-old hearts, but did markedly inhibit glycolysis and glucose oxidation in 7-day-old hearts. A series of hearts were also subjected to periods (25-60 min) of no-flow ischemia, followed by 30 min of aerobic reperfusion. In the absence of palmitate, 1-day-old hearts subjected to ischemic periods of up to 60 min recovered some degree of mechanical function during reperfusion, whereas 7-day-old rabbit hearts failed to recover if hearts were subjected to ischemic periods of 35 min or longer.(ABSTRACT TRUNCATED AT 250 WORDS)

Effects of sphingosine, albumin and unsaturated fatty acids on the activation and translocation of phosphatidate phosphohydrolases in rat hepatocytes

The activities of two phosphatidate phosphohydrolases were measured in cultured rat hepatocytes incubated with 0.1 mM albumin. The activity, which is inhibited by N-ethylmaleimide (PAP-1) is located in the cytosolic and membrane fractions. PAP-1 activity is stimulated by Mg 2+ and it can be translocated from the cytosol to the membranes by relatively low (0.5–1 mM) concentrations of fatty acids. In addition, higher concentrations (1–3 mM) of fatty acids cause an increase in the total PAP-1 activity. Translocation of PAP-1 activity in the hepatocytes is preferentially promoted by unsaturated fatty acids (C 18:1, C 18:2, C 18:3, C 20:4 and C 20:5), rather than by saturated acids (C 14:0, C 16:0, C 18:0). Increasing the extracellular concentration of albumin from 30 μM to 1 mM displaces PAP-1 activity from the membrane fraction. Sphingosine, but not staurosporine, can inhibit the redistribution of PAP-1 activity induced by oleate. The amphiphilic amines, sphingosine, chlorpromazine and propranolol, also decrease membrane-bound PAP-1 activity in the absence of fatty acids, but they do not alter, significantly, the activity of the cytosolic PAP-1. In the presence of 1 mM oleate, sphingosine, chlorpromazine and propranolol decrease the translocation of PAP-1 from the cytosol to the membranes. The phosphohydrolase activity, which is insensitive to N-ethylmaleimide (PAP-2), is specifically located in the plasma membrane (Jamal, Z., Martin, A., Gomez-Muñoz, A. and Brindley, D.N. (1991) J. Biol. Chem. 266, 2988–2996) and it is not stimulated by Mg 2+. Saturated fatty acids, albumin, sphingosine and propranolol have no significant effects on PAP-2 activity. However, chlorpromazine decreases PAP-2 activity by about 14%. Linolenate, arachidonate and eicosapentaenoate at 1 mM also produced small (7–10%) decreases in PAP-2 activity. It is proposed that both PAP-1 and PAP-2 activities may be involved in signal transduction, although the main function of PAP-1 seems to be involved in the synthesis of glycerolipids.

Carnitine stimulation of glucose oxidation in the fatty acid perfused isolated working rat heart.

The effects of L-carnitine on myocardial glycolysis, glucose oxidation, and palmitate oxidation were determined in isolated working rat hearts. Hearts were perfused under aerobic conditions with perfusate containing either 11 mM [2-3H/U-14C]glucose in the presence or absence of 1.2 mM palmitate or 11 mM glucose and 1.2 mM [1-14C]palmitate. Myocardial carnitine levels were elevated by perfusing hearts with 10 mM L-carnitine. A 60-min perfusion period resulted in significant increases in total myocardial carnitine from 4376 +/- 211 to 9496 +/- 473 nmol/g dry weight. Glycolysis (measured as 3H2O production) was unchanged in carnitine-treated hearts perfused in the absence of fatty acids (4418 +/- 300 versus 4547 +/- 600 nmol glucose/g dry weight.min). If 1.2 mM palmitate was present in the perfusate, glycolysis decreased almost 2-fold compared with hearts perfused in the absence of fatty acids. In carnitine-treated hearts this drop in glycolysis did not occur (glycolytic rates were 2911 +/- 231 to 4629 +/- 460 nmol glucose/g dry weight.min, in control and carnitine-treated hearts, respectively. Compared with control hearts, glucose oxidation rates (measured as 14CO2 production from [U-14C]glucose) were unaltered in carnitine-treated hearts perfused in the absence of fatty acids (1819 +/- 169 versus 2026 +/- 171 nmol glucose/g dry weight.min, respectively). In the presence of 1.2 mM palmitate, glucose oxidation decreased dramatically in control hearts (11-fold). In carnitine-treated hearts, however, glucose oxidation was significantly greater than control hearts under these conditions (158 +/- 21 to 454 +/- 85 nmol glucose/g dry weight.min, in control and carnitine-treated hearts, respectively). Palmitate oxidation rates (measured as 14CO2 production from [1-14C]palmitate) decreased in the carnitine-treated hearts from 728 +/- 61 to 572 +/- 111 nmol palmitate/g dry weight.min. This probably occurred secondary to an increase in overall ATP production from glucose oxidation (from 5.4 to 14.5% of steady state myocardial ATP production). The results reported in this study provide direct evidence that carnitine can stimulate glucose oxidation in the intact fatty acid perfused heart. This probably occurs secondary to facilitating the intramitochondrial transfer of acetyl groups from acetyl-CoA to acetylcarnitine, thereby relieving inhibition of the pyruvate dehydrogenase complex.

Myocardial triglyceride turnover and contribution to energy substrate utilization in isolated working rat hearts

The objective of this study was to determine the contribution of myocardial triglycerides to overall ATP production in isolated working rat hearts. Endogenous lipid pools were initially prelabeled (pulsed) by perfusing hearts for 60 min with Krebs-Henseleit buffer containing 1.2 mM [1-14C]palmitate. During a subsequent 60-min period (chase), hearts were perfused with either no fat, low fat (0.4 mM [9,10-3H] palmitate), or high fat (1.2 mM [9,10-3H]palmitate). All buffers contained 11 mM glucose. During the "chase," 14CO2 production (a measure of endogenous fatty acid oxidation) and 3H2O production (a measure of exogenous fatty acid oxidation) were determined. Oxidative rates of endogenous fatty acids during the chase were 279 +/- 50, 88 +/- 14, and 88 +/- 8 nmol of [14C]palmitate oxidized per g dry weight.min in the no fat, low fat, and high fat groups, respectively, compared to exogenous palmitate oxidation rates of 0, 361 +/- 68, and 633 +/- 60 nmol of [3H]palmitate/g dry weight.min, in the no fat, low fat, and high fat groups, respectively. Endogenous [14C]palmitate oxidation rates were matched by loss of [14C]palmitate from endogenous myocardial triglycerides. Overall triglyceride content decreased during the no fat and low fat chase perfusion but did not change during the high fat chase. Loss of triglyceride [14C]palmitate during the high fat chase was matched by incorporation of exogenous [3H]palmitate in triglycerides. In a second series of perfusions, three groups of hearts were perfused under similar conditions, except that unlabeled palmitate was used during the "pulse" and that 11 mM [2-3H/U-14C]glucose and unlabeled palmitate was present during the chase. During the chase, both glycolysis (3H2O production) and glucose oxidation (14CO2 production) rates were measured. Rates of glucose oxidation were inversely related to the fatty acid concentration in the perfusate (1257 +/- 158, 366 +/- 40, and 124 +/- 26 nmol of glucose oxidized per min.g dry weight in the no fat, low fat, and high fat groups, respectively), while rates of glycolysis were not significantly different between these groups. Calculation of overall ATP production from both oxidative and glycolytic sources determined that even in the presence of high concentrations of fatty acids, myocardial triglyceride turnover can provide over 11% of steady state ATP production in the aerobically perfused heart. In the absence of fatty acids, myocardial triglyceride fatty acids can become the major energy substrate of the heart.(ABSTRACT TRUNCATED AT 400 WORDS)

Fatty acid incorporation into membranes of dispersed rat submandibular salivary gland cells and their effect on adenylate cyclase activity

Dispersed cells from rat submandibular salivary glands were incubated in medium supplemented with different fatty acids, such as stearic (18:0), oleic ( cis 18:1 ω9) and elaidic acid ( trans 18:1 ω9). The exogenous fatty acids were incorporated into the membrane lipids. A comparison of the adenylate cyclase activity in membranes of cells incubated with different fatty acids revealed the following order (from highest to lowest specific activity): stearic, elaidic, oleic. The findings suggest that changes in adenylate cyclase activity in these dispersed membranes enriched with different fatty acids may be related to the possible changes in membrane fluidity. The synthesis of glycoproteins was studied by measuring the incorporation of [1- 14C]-glucosamine into TCA-PTA-precipitable material in the presence or absence of fatty acids. No effect of the exogenous fatty acids on glycoprotein synthesis was observed.

Klebsiella pneumoniae strain K21: evidence for the rapid secretion of an unacylated form of pullulanase.

Klebsiella pneumoniae strain PAP996 was previously shown to secrete fatty acylated, aggregated (micellar) pullulanase only after the end of exponential growth. Here we show that the closely related strain K21 secretes large amounts of unacylated, non-aggregated (monomeric) pullulanase during exponential growth. Only a small amount (less than 10%) of the secreted pullulanase was initially retained by the exponentially growing cells to be subsequently secreted in a fatty acylated, aggregated form. Despite the absence of fatty acids in secreted monomeric pullulanase, the effects of the antibiotic globomycin on pullulanase maturation indicated that all of the enzyme synthesized by strain K21 is processed by lipoprotein signal peptidase.

Lipid permeability of rat jejunum and ileum: correlation with physical properties of the microvillus membrane

It is now generally accepted that dietary lipids permeate through the cholesterol-phospholipid bilayer of the intestinal microvillus membrane during the process of intestinal absorption. Therefore, it has been assumed that rates of lipid permeation depend upon the physical properties of the microvillus membrane. In this study the lipid permeability properties of the microvilus membrane were compared in two regions of the intestine, jejunum and ileum. Since the jejunum is exposed to the majority of dietary lipid it would be reasonable to suppose that it would be more efficient at lipid absorption. The ileum was found to be less permeable to all fatty acids examined and this could be correlated with increased rigidity of ileal microvillus membrane vesicles measured with multiple fluorescent probes. Differences in membrane fluidity were found in both the outer third and central regions of the bilayer. When measurements of membrane fluidity were performed either in the presence or the absence of fatty acids, it could be demonstrated that these acids perturb the physical properties of the outer region or the membrane. Therefore, this suggests that the rate-limiting step in fatty acid permeation may be localized to the outer third of the bilayer. Pharmacologic or dietary manipulations attempting to alter rates of lipid permeability should, therefore, be directed towards altering the physical properties of this region of the microvillus membrane.

Structural identifications of straight-chain fatty acids and esters in coal extracts by linked scanning mass spectrometry

Structural identifications of geochemically significant straight-chain fatty acids and esters in coal extracts were carried out by linked scanning mass spectrometry together with field desorption mass spectrometry. The results obtained demonstrate the usefulness of the technique for direct analysis of complex mixtures to elucidate detailed molecular structures of individual constituents. The extracts of lignites contain straight-chain fatty acids with C 24 to C 34 and long-chain fatty esters with C 48 to C 64, the latter being missing from subbituminous coals and neither is found in those of bituminous coals. The free fatty acids, the acyl and the alkoxyl groups of esters all extend from C 24 to C 34 and are qualitatively similar to each other in carbon-number distribution indicating that they were probably derived from common precursor compounds. The presence and/or absence of fatty acids and fatty esters parallels the rank of coals and may be connected with chemical changes brought about during maturation, such as hydrolysis of the esters, conversions of the acids into paraffins, etc.

Bacterial contribution to sedimentary organic matter; a comparative study of lipid moieties in bacteria and Recent sediments

A systematic study of the lipid composition of thirteen bacterial species and three Recent sediments (methanogenic sediment, cyanobacterial mat and evaporative gypsum crust) was undertaken in an attempt to recognize bacterial organic matter in sediments. A sequential method, which distinguishes between three different modes of occurrence of lipid moieties (free, OH −- and H +-labile), was applied. The acid-labile fractions are discussed. The three main groups of bacteria, archaebacteria, gram-positive eubacteria and gram-negative eubacteria, are easily distinguished. Methanogenic and extremely halophilic archaebacteria are characterized by the presence of diphytanyl glyceryl ether and the absence of fatty acids. The gram-positive eubacteria contain primarily iso- and anteiso-branched fatty acids whereas the gram-negative bacteria and sediments are dominated by β- and α-hydroxy fatty acids. A wide variety of H +-labile hydroxy fatty acids was observed which included several, as yet unknown, structures. β-Hydroxy fatty acids in this H +-labile mode of occurrence are exclusively present in bacteria. Their distribution patterns in sediments are considered “fingerprints” of past and present bacterial populations. The specific differences in β -hydroxy fatty acid compositions observed in the different bacteria and the three sediments investigated, suggest that amide-linked β-hydroxy fatty acid patterns are useful as markers of bacterial populations and therefore of environmental conditions.

Stimulation of the Ca 2+-dependent polymerization of synexin by [formula omitted]-unsaturated fatty acids

The influence of fatty acids on the polymerization of synexin was studied by monitoring light scattered from solutions of purified synexin. Cis -unsaturated fatty acids such as arachidonate or oleate stimulated synexin polymerization at sub-micromolar concentrations, while saturated fatty acids, a trans unsaturated fatty acid or a fatty acid methyl ester had little effect. The polymerization of synexin occurred at lower concentrations of Ca 2+ in the presence of the fatty acids than in the absence of fatty acids. Therefore, Ca 2+ and free fatty acids may act as co-regulators of synexin action in stimulated secretory cells.

Free fatty acid analysis of the early proterozoic animikie group, Minnesota and Ontario

The Early Proterozoic iron formation-slate sequences of the Animikie Group have been analyzed for fatty acids and the results discussed in light of the regional metamorphic history and kerogen H/C and N/C atomic ratios. No fatty acids, free or inorganically bound, were detected. The highest H/C ratios are found in the Gunflint (mean = 0.57) and lowest in the Virginia State (0.19). The lower H/C ratio in the Biwabik (mean = 0.45) is interpreted as a function of higher metamorphic grade in that iron formation. The absence of fatty acids is attributed to dehydrogenation and cyclization of the original material to the present H/C ratio of about 0.5. The Gunflint Iron-Formation, which represents those conditions most likely to preserve chemical fossils in the Animikie Group has already exceeded minimum conditions for fatty acid preservation. Hydrogen to carbon ratios in pelitic rocks are consistently lower than their underlying iron-formation. It is suggested that sulfur and/or clay alter the kinetics of the dehydrogenation reaction, creating lower H/C ratios in the pelites.

Genetic analysis and characterization of a Caulobacter crescentus mutant defective in membrane biogenesis.

A mutant of Caulobacter crescentus has been isolated which has an auxotrophic requirement for unsaturated fatty acids or biotin for growth on medium containing glucose as the carbon source. This mutant exhibits a pleiotropic phenotype which includes (i) the auxotrophic requirement, (ii) cell death in cultures attempting to grow on glucose in the absence of fatty acids or biotin, and (iii) a major change in the outer membrane protein composition before cell death. This genetic lesion did not appear to affect directly a fatty acid biosynthetic reaction because fatty acid and phospholipid syntheses were found to continue in the absence of supplement. Oleic acid repressed fatty acid biosynthesis and induced fatty acid degradation in the wild-type parent, AE5000 . The mutant strain, AE6000 , was altered in both of these regulatory functions. The AE6000 mutant also showed specific inhibition of the synthesis of outer membrane and flagellar proteins. Total phospholipid, DNA, RNA, and protein syntheses were unaffected. The multiple phenotypes of the AE6000 mutant were found to cosegregate and to map between hclA and lacA on the C. crescentus chromosome. The defect in this mutant appears to be associated with a regulatory function in membrane biogenesis and provides evidence for a direct coordination of membrane protein synthesis and lipid metabolism in C. crescentus.

A histochemical study of the metabolism of rat renal arteries and arterioles.

A histochemical study of the metabolism of rat renal arteries and arterioles. Rat renal arteries and arterioles were examined histochemically to determine their metabolic profiles. Succinate, malate and NAD-isocitrate dehydrogenase, cytochrome oxidase and ubiquinone were assessed to determine aerobic metabolism. Glucose-6-phosphate dehydrogenase and DPN diaphorase were evaluated to determine hexose-monophosphate-shunt activity. Anaerobic metabolism was evaluated via lactate dehydrogenase, and the substrate, glycogen. Gomori's lipase, beta-hydroxybutyrate dehydrogenase and amounts of neutral fat and free fatty acids were assessed as indicators of lipid utilization. Myosin ATPase activity was evaluated as an index of ATP utilization for contraction. Deoxyribonucleic and ribonucleic acids were appraised as indicators of protein synthesis. In general, the oxidative enzymes and myosin ATPase demonstrate considerable activity in renal arteries and arterioles which suggests aerobic metabolism and ATP usage. Renal arteries and arterioles also appear capable of anaerobic metabolism as indicated by strong lactate dehydrogenase reactivity and by the presence of slight to moderate quantities of glycogen, while high levels of glucose-6-phosphate dehydrogenase and moderate amounts of deoxyribonucleic acid suggest a potential for beta-hydroxybutyrate dehydrogenase, minimal lipase activity, and the absence of fatty acids with substantial amounts of neutral fat, indicate limited lipid catabolism.

The effect of fatty acid exposure on the biosynthesis of glycerolipids by cultured hepatocytes

Incubation of hepatocyte monolayers with oleate or palmitate (1.0 mM) for 2–48 h, increased (20 to 80%) the incorporation of [1,3- 14C]glycerol and palmitate into triacyglycerol but not phosphatidylcholine. The effect of fatty acids on liver cell triacylglycerol formation correlated well ( r = 0.990) with a simultaneous rise (2–4-fold) in phosphatidate phosphatase (EC 3.1.3.4) activity. Phosphatidate phosphatase activity and triacylglycerol biosynthesis are also increased (2-fold) after hepatocyte monolayers are incubated for 24 h with cyclic GMP in the absence of fatty acids. Fatty acid-dependent increases in liver cell triacylglycerol formation and phosphatidate phosphatase activity are not blocked by cycloheximide. Phosphatidylcholine biosynthesis was also elevated in homogenates of liver cells exposed (24–48 h) to 1.0 mM oleate when exogenous CDPcholine was added to the incubation mixture. Apparently, the phosphatidate phosphatase-dependent rise in diacylglycerols that occurs after fatty acid exposure is primarily shunted into triacylglycerols because liver cell CDPcholine content is not correspondingly increased, and high levels of diacylglycerol acyltransferase (EC 2.3.1.20) and fatty acyl-CoA derivatives are present.

Effects of unsaturated fatty acids on metabolism of benzo[a]pyrene in an NADPH-fortified rat liver microsomal system.

Modulation of microsome mediated benzo[a]pyrene (BP) metabolism by oleic and linoleic acids was studied. Oleic and linoleic acids did not influence the apparent activity of aryl hydrocarbon hydroxylase or the relative ratios of BP-7,8-dihydrodiol to phenol metabolites on high performance liquid chromatography. The total binding of BP-metabolites to DNA was not influenced much by the presence of oleic acid, but was inhibited significantly by linoleic acid (p less than 0.05). The quantity of BP-metabolite bound adducts was determined by Sephadex LH-20 column chromatography with a methanol gradient. The amount of adducts bound with the anti-isomer of BP-7,8-dihydrodiol-9,10-oxide (diol-epoxide) was more than that with 9-hydroxybenzo[a]pyrene-4,5-oxide in the absence of fatty acids, and vice versa in the presence of fatty acids. The presence of 1, 2 or 5 microliters/ml oleic acid decreased the amounts of adducts with the anti- and syn-isomers of the diol-epoxide but not those with 9-hydroxybenzo[a]pyrene-4,5-oxides, whereas the presence of 0.08 - 2 microliters/ml of linoleic acid decreased the amounts of all these adducts but to different extents, resulting in predominance of 9-hydroxybenzo[a]pyrene-4,5-oxide derived adducts over anti-isomer adducts of the diol-epoxide. These observations suggest that endogenous materials that do not have any enzyme activity may have important influences on the metabolism of chemical carcinogens.

Effect of Fatty Acids on Fertilization and Development of Mouse Embryos In Vitro

The interaction of protein and fatty acids on the fertilization and preimplantation development of mouse embzyos in vitro was investigated.Normal fraction V and fatty‐acid‐free bovine serum albumin (V‐BSA and FAF‐BSA) supported high rates of fertilization, but the addition of palmitic and/or oleic acids inhibited fertilization of mouse ova in vitro. Trichloroacetic acid‐extracted BSA (TCA‐BSA) totally inhibited fertilization, even in the absence of fatty acids. The normal V‐BSA was capable of supporting the development of one‐cell zygotes and, later, the preimplantation stages to fully expanded hatched blastocysts. Only 50% of oneand two‐cell embryos developed to fully expanded blastocysts in the presence of FAF‐BSA; TCA‐BSA did not support continued development to the blastocyst stage until culture was initiated at the eight‐cell stage. Oleic acid was better than palmitic acid, and the combination of both acids was best in promoting the formation and hatching of blastocysts from the one‐cell stage in medium containing FAF‐BSA. Thus, exogenous fatty acids inhibit fertilization of mouse ova, but they are required for the development of embryos.

Triacylglycerol metabolism in kidney cortex and outer medulla

1. 1. Triacylglycerol (TAG) metabolism was studied with a fully enzymic method, in tubule fragments from rat kidney cortex and outer medulla isolated by collagenase treatment. 2. 2. TAG content of freshly prepared cortical tubules correlated well with plasma fatty acid levels of the rats. 3. 3. Presence of fatty acids in the incubation medium led to a net synthesis of TAG, whereas TAG content decreased in the absence of fatty acids. 4. 4. Gluconeogenic substrates stimulated TAG synthesis from oleate in cortical tubules. Glucose, which was not stimulatory in the cortex, provided glycerol moieties in the outer medulla. 5. 5. Label from newly formed TAG preincubated with [ 14Cl]-oleate was quantitatively recovered in 14CO 2, indicating oxidative breakdown as the metabolic fate of tubular TAG.