Effect of microalgal diets and commercial wheatgerm flours on the lipid profile of Ruditapes decussatus spat

The influence of both the lipid composition of microalgal diets and commercial flours on the lipid classes and fatty acids of Ruditapes decussatus spat was studied. These aspects of the nutritional value of the diets were discussed in relation to the growth of the spat. Four diets were tested; Diet A, composed of 100% of the daily food ration of microalgae; Diet B, composed of 100% of wheatgerm; Diet C, composed of 50% of microalgae and 50% of wheatgerm; and Diet D, composed of 25% of microalgae and 75% of wheatgerm. The microalgal cells present a higher lipid content than that for wheatgerm. Tahitian Isochrysis cells have phospholipids and triacylglycerols as majority lipids, whereas in the wheatgerm particles, the lipids more abundant are triacylglycerols. Fatty acid content was higher in the microalgal cells than in the wheatgerm particles. The n-3 fatty acids were the most abundant acids in the microalgae, whereas the n-6 fatty acids were in the wheatgerm. The n-3 PUFA were not detected in wheatgerm. Phospholipids were the main lipids present in the clam spat, followed by triacylglycerols. Other lipid classes, detected in significantly lower amounts, included free fatty acids, sterols, and sterol ester + waxes. The composition of fatty acids in the spat was influenced by the fatty acid composition of the diet. Highest spat growth rates were observed with those diets that present a higher phospholipid/triacylglycerol relation. A negative correlation in the relation n-6/n-3 vs. growth has also been observed, with better growth rates in diets with a lower ratio. If the fatty acid 20:5n-3 and 22:6n-3 considered "essential" for marine animals were not present in the diet, they were not present in the spat either. Desaturation and elongation capabilities of R. decussatus spat were also discussed.     

Fatty acid composition and properties of the liver microsomal membrane of rats fed diets enriched with cholesterol.

Male rats were fed diets containing olive (OO) or evening primrose (EPO) oil (10% w/w), with or without added cholesterol (1% w/w). After 6-week feeding, the lipid and fatty acid compositions, fluidity, and fatty acid desaturating and cholesterol biosynthesis/esterification related enzymes of liver microsomes were determined. Both the OO and EPO diets, without added cholesterol, increased the contents of oleic and arachidonic acids, respectively, of rat liver microsomes. The results were consistent with the increases in delta 9 and delta 6 desaturation of n-6 essential fatty acids and the lower microviscosity in the EPO group. Dietary cholesterol led to an increase in the cholesterol content of liver microsomes as well as that of phosphatidylcholine (PC). The cholesterol/phospholipid and PC/PE (phosphatidylethanolamine) ratios were also elevated. Fatty acid composition changes were expressed as the accumulation of monounsaturated fatty acids, with accompanying milder depletion of saturated fatty acids in rat liver microsomes. In addition, the arachidonic acid content was lowered, with a concomitant increase in linoleic acid, which led to a significant decrease in the 20:4/18:2 ratio in comparison to in animals fed the cholesterol-free diets. Cholesterol feeding also increased delta 9 desaturase activity as well as membrane microviscosity, whereas it decreased delta 6 and delta 5 desaturase activities. There was a very strong correlation between fluidity and the unsaturation index reduction in the membrane. Furthermore, the activity of hydroxymethylglutaryl-CoA reductase increased and the activity of acyl-CoA:cholesterol acyltransferase decreased in liver microsomes from both cholesterol-fed groups.(ABSTRACT TRUNCATED AT 250 WORDS)     

Lipid composition of Ruditapes philippinarum spat: effect of ration and diet quality

This study investigates the influence of the lipid composition of microalgal and commercial flour diets on the lipid classes and fatty acids of Ruditapes philippinarum spat. Aspects of the nutritional role of the diets and the feeding ration are discussed with regard to previously published spat growth data. Our results demonstrated that clams showed the best growth rates when fed with diets that supplied a larger quantity of lipids, further characterised by a high content of phospholipids and triacylglycerols. We observed a significant correlation between the amount of triacylglycerols (r=0.929, p<0.05) and phospholipids (r=0.781, p<0.05) supplied and spat growth. In addition, R. phillipinarum spat reached the highest percentages of triacylglycerols (about 12%) and the lowest percentages of phospholipids (about 60%) and sterols (about 4%) with these growth-promoting diets. Spat fed with the other diets and/or rations showed lower growth rates and significantly lower quantities of triacylglycerols. In the present study, the alternative essentiality of 20:5n-3 and/or 22:6n-3 is confirmed. The diminishing supply of 22:6n-3 without an increase of 20:5n-3 has an effect on the growth of the spat. The dietary composition of fatty acids influenced the fatty acid profiles in bivalves. The results of our study would suggest that R. philippinarum is incapable of transforming 18:3n-3 to 20:5n-3 and then to 22:6n-3. Accordingly, although diets contained 18:3n-3, the spat reflected the low content of 20:5n-3 of the diets. With respect to 22:6n-3, given that this fatty acid is present in high quantities in Isochrysis, the spat content of this fatty acid was relative to its content in the diet. This study showed that clams with the lowest growth rates presented an increase in 20:4n-6. In the spat fed with the microalgal diets, 18:2n-6 scarcely reached 2% whereas in spat fed with wheat germ 18:2n-6 amounted to 18% of the total fatty acids. This fatty acid, by means of elongation, transforms to 20:2n-6, which also appeared in important quantities in the lipids of the spat fed totally or partially by wheat germ. We note that 20:2n-6 did not originate from the diet since it is absent in the microalgae and the flour. The desaturation of 20:2n-6 to 20:3n-6 has not been observed (low levels of 20:3n-6 in all cases) and therefore it can be assumed that the observed levels of 20:4n-6 were diet-related.     

Fatty acid composition and lipid peroxidation of soft-shelled turtle, Pelodiscus sinensis, fed different dietary lipid sources

Juvenile soft-shelled turtles (Pelodiscus sinensis) were fed 7 diets containing 8% of lard, soybean oil, olive oil, menhaden fish oil, or mixtures of 1 to 1 ratio of fish oil and lard, soybean oil, olive oil for 10 weeks. Growth and muscle proximate compositions of the turtles were not affected by different dietary treatments (p>0.05). Fatty acid profiles in muscle polar lipids, muscle non-polar lipids, and liver polar lipids reflected the fatty acid composition of dietary lipid source. Turtles fed diets containing fish oil generally contained significantly higher (p<0.05) proportion of highly unsaturated fatty acids (HUFA) in both polar and non-polar lipids of muscle and polar fraction of liver lipids than those fed other oils. Non-polar fraction of liver lipids from all groups of turtles contained less than 1% of HUFA. All turtles contained relatively high proportions of oleic acid in their lipids regardless of the dietary lipid source. Further, lipid peroxidation in both muscle tissue and liver microsomes of turtles fed fish oil as the sole lipid source was greater (p<0.05) than those fed fish oil-free diets. Turtles fed olive oil as the sole lipid source had the lowest lipid peroxidation rate among all dietary groups. The results indicate that dietary n-3 HUFA may not be crucial for optimal growth of soft-shelled turtles although they may be used for metabolic purpose. Further, high level of dietary HUFA not only increases the HUFA content in turtle tissues, but also enhances the susceptibility of these tissues to lipid peroxidation.     

Tissue fatty acid composition of pigs fed different fat sources

Dietary fat influences the physico-chemical properties of meat, and fatty acid (FA) composition may have implications on human health. The objectives of the experiment were to study tissue FA partitioning and the effect of dietary fat source on tissue FA composition. Seventy crossbred gilts (61.8 ± 5.2 kg BW average) were fed one of seven treatments: a diet containing a very low level of fat (no fat (NF)) and six fat-supplemented diets (10%: tallow (T), high-oleic sunflower oil (HOSF), sunflower oil (SFO), linseed oil (LO), fat blend (FB: 55% tallow, 35% SFO, 10% LO) and fish oil blend (FO: 40% fish oil, 60% LO). Differential tissue FA depositions were observed, with flare fat being the most saturated, followed by intermuscular, and subcutaneous being the least saturated. Monounsaturated fatty acid (MUFA) deposition showed an opposite tissue pattern. Subcutaneous fat showed the highest MUFAs, intermuscular fat showed intermediate values and flare fat showed the lowest MUFAs. Intramuscular polyunsaturated fatty acid (PUFA) content was less susceptible to dietary treatment modifications compared with other depots. Significant tissue FA modifications were observed due to dietary treatments, mainly in diets rich in PUFA. The saturated fatty acids (SFA) were high in NF-fed and low in HOSF-fed animals, MUFA were high in HOSF-fed and low in SFO-, LO- and FO-fed animals, while PUFA were high in SFO- and LO-fed and low in HOSF-, T- and NF-fed animals. Pigs fed LO and FB showed detectable levels of EPA, which depended on the linolenic content of the diet. The only effective way to increase tissue DHA contents was to add DHA in the diet through FO feeding. Araquidonic acid was high in SFO diets and low in LO and FB diets, and also high in intramuscular fat compared with other tissues. EPA and DHA were also high in intramuscular fat compared with other fat depots. The deposition of oleic and linoleic acids depended on the composition of dietary fat, as their deposition varied between diets, even at similar levels of intake of each FA. The NF diet resulted in the greatest proportion of SFAs (palmitic and stearic) of all treatments tested. SFAs were less susceptible to modification than MUFA in response to the different PUFA levels supplemented in the diet. T resulted in less fat deposition in some of the fat depots and more in others, suggesting that T could partition fat differently among fat depots.     

Changes in fatty acid composition in Ruditapes philippinarum A & R (Veneridae) fed on industrial yeast.

1. The fatty acid composition of short-neck clams (Ruditapes philippinarum A & R) was compared in animals (a) fed on industrial yeast, (b) fed on natural phytoplankton, (c) after starvation. 2. Marked deficiencies in polyunsaturated fatty acids were found in the case of a yeast diet as well as after starvation. 3. Metabolic changes are discussed.     

13种微藻的脂肪酸组成分析

分析了13种微藻(包括7种绿藻,5种杂色藻和1种红藻)的总脂含量和脂肪酸组成,结果表明,不同门类微藻的脂肪酸组成差异较大:绿藻的脂肪酸组成以C16和C18为主;杂色藻类的脂肪酸组成相近,金藻门含有14:0、16:0、18:1、18:4等特征脂肪酸,三角褐指藻主要的脂肪酸为14:0、16:0、16:1、16:3和20:5,而粉核油球藻的脂肪酸以14:0、16:0、20:5为主;紫球藻的脂肪酸组成以16:0、20:4和20:5为主。在测试的13种微藻中,杜氏盐藻的亚麻酸含量最高,占总脂肪酸的60.9%;等鞭金藻的十八碳四烯酸含量最高,占总脂肪酸的19.6%;紫球藻和粉核油球藻中花生四烯酸与二十碳五烯酸(EPA)含量分别占总脂肪酸的17.1%和20.9%。     

In situ endocrine disrupting effects of cadmium on the reproduction of Ruditapes decussatus

The gulf of Gabès is well known for its multiple contaminations which are closely associated with the past and present industrial and anthropogenic activity. In order to evaluate in situ the cadmium bioaccumulation in the clam Ruditapes decussatus sampled in this area, we measured cadmium concentrations in the whole soft tissues and in the digestive gland during one year. Energy reserves (proteins, glycogen, lipids) were monitored during gametogenesis in the remainder (mantle, adductor muscle, foot, siphons) of clams. Sex steroids (progesterone, testosterone, estradiol-17beta) were also measured by radio-immunoassay (RIA) in the gonads. The results showed that cadmium varied according to the reproductive cycle. High values were recorded at the resting stage in both sexes, during the gamete development and maturation in males and at the ripening and partially spawn stages in females. No significant changes in protein levels were observed in both females and males. However, high levels of glycogen and lipid reserves were recorded during the gametogenesis activity (from the development to the partially spawn stages). For steroid analyses, the results showed no important changes in testosterone levels all along the reproductive cycle. Fluctuations of sex steroids (especially progesterone and estradiol-17beta) could suggest their possible role as endogenous modulators of gametogenesis in R. decussatus. Correlation matrix and multiple regression models were also proposed to describe negative and significant relationship between cadmium and (glycogen, progesterone, testosterone and estradiol-17beta). These correlations may suggest the involvement of cadmium in the dysfunction of energy status and the endocrine disruption which could impede reproduction.     

Fatty acid composition of different serum phospholipids in men and women

1. Eight young healthy persons, four men and four women, were maintained for a total of 2 months on a diet in which 40%, 16% and 44% of the total calories were present as fats, proteins and carbohydrates respectively. The ratio of complex to simple carbohydrates in the diet was 1:4. 2. The fatty acids of serum kephalins, lecithins, lysolecithins and sphingomyelins were determined by gas-liquid column chromatography. 3. Lysolecithins in both men and women had the highest content of saturated acids, followed by sphingomyelins, lecithins and kephalins in that order. The degrees of saturation and of polyunsaturation of the fatty acids in the different phospholipid fractions were significantly different, except for the differences in the polyunsaturation of the kephalins and lecithins. 4. No sex difference was found in the fatty acid composition of the different phospholipids.     

Amino acid and dipeptide absorption in rats fed chemically defined diets of differing fiber composition

In rats chronically fed a fiber-free diet or one of the three nutritionally equivalent fiber-containing diets, in vivo jejunal absorption of L-leucine from a free amino acid mixture of L-leucine and glycine as well as equimolar solutions of the dipeptides, L-leucyl-glycine and glycyl-L-leucine, were compared. In addition, total and brush border amino peptidase activities for the two dipeptide substrates were examined in small bowel segments. With two of three fiber diet groups, absorption of L-leucine from the free amino acid solution was reduced without a detectable change in peptide transport or aminopeptidase activities. This investigation provides evidence that peptide transport mechanisms are relatively spared with long-term feeding of fiber-containing diets similar to observations recorded in disease states associated with protein-energy malnutrition.     

Fatty acid composition and conjugated linoleic acid content of different tissues in rats fed individual conjugated linoleic acid isomers given as triacylglycerols small star,filled

HEAT TREATMENT OF VEGETABLE OILS GAVE RISE TO FOUR MAIN CONJUGATED LINOLEIC ACID (CLA) ISOMERS : the 9c,11t, 9t,11t, 10t,12c and 10t,12t. The diet of male Wistar rats was supplemented with 150 mg/day either 9c,11t-, 9t,11t-, 10t,12c- or 10t,12t CLA isomers for 6 days and their effects on lipid composition were investigated in liver, heart, skeletal muscle Gastrocnemius, kidneys, brain and adipose tissue. The incorporation of all isomers was low (< 1.4%) and the level was as follows : adipose tissue > Gastrocnemius > liver, kidneys > brain. The main changes in the overall lipid composition were observed in skeletal muscle (Gastrocnemius) and in heart and were associated with feeding the 10t,12c and 10t,12t isomers. The diet enriched in 10t,12t CLA decreased the total long chain polyunsaturated fatty acid proportion in Gastrocnemius (from 18.4% to 14.4%) and increased that of 20:4 n-6 in heart (from 16.9 to 19.3%). The diet enriched in 10t,12c CLA decreased the monounsaturated fatty acid proportion in Gastrocnemius (from 32.0 to 26.1%) and produced an effect similar to the 10t,12t in heart. By contrast, the 9c,11t and 9t,11t isomers did not affect fatty acid composition in all tissues and organs. We concluded that ingestion of 10t,12c and 10t,12t CLA present in oils and in CLA mixtures could change muscle lipid composition.     

Virus-like particles associated with mortalities of the carpet-shell clam Ruditapes decussatus

During the late summer and early fall of 1997 and 1998 heavy mortalities were detected in the carpet-shell clam Ruditapes decussatus cultured in Galicia (NW Spain). The prevalences and intensities of the parasites found in the histopathological studies were not high enough to explain the high mortality rates. Unenveloped virus-like particles were detected by transmission electron microscopy in the cytoplasm of the connective tissue cells. They had an icosahedrical-spherical shape with a diameter of 27 to 35 nm. These virus-like particles appeared free in the cytoplasm or associated with endoplasmic reticulum membranes. These characteristics suggest that they belong to the Picornaviridae family.     

Fatty acid composition ofAerobacter aerogenes

The fatty acid composition of the whole cell and cell wall ofAerobacter aerogenes was studied employing column and gas-chromatographic technique. The cell wall contained a greater percentage of total lipid, complex lipid, and free fatty acids compared to the whole cell. Palmitic acid and oleic acid were the most abundant fatty acids found in the free fatty acid and complex lipid fractions. A saturated C₁₇ fatty acid and small quantities of a branched C₁₆ and iso and anteiso C₁₂ fatty acids were detected. The glyceride fractions of the whole cell and cell wall contained very few fatty acids.     

Changes in fatty acid composition of Mytilus galloprovincialis (Lmk) fed on microalgal and wheat germ diets

Dietary fatty acid incorporation and changes in various lipid and phospholipid classes in the mussel Mytilus galloprovincialis subjected to three different dietary regimens were analysed and compared. Group A was unfed; group B received a diet consisting of 100% Thalassiosira weissflogii, exhibiting the typical fatty acid composition of diatoms, and group C received a diet consisting of 100% wheat germ conferring a 18:2:n-6 abundance. Biochemical analyses of diets and mussels were carried out at the beginning and at the end of the 30-day experimental period. Starvation and T. weissflogii based diet poorly affected mussel growth and fatty acid composition which remained unchanged. On the contrary, the wheat germ-based diet increased the condition index and deeply affected the fatty acid profile of all lipid and phospholipid classes. The high dietary 18:2n-6 level drastically reduced tissue content of 20:4n-6, 20:5n-3 and 22:6n-3. The biosynthesis of Non Methylene Interrupted (NMI) dienoic fatty acid appeared to be insensitive to the high input of 16:1n-7 and 18:1n-9 respectively from diet B and C, and to the PUFA shortage of diet C. Nevertheless the two NMI trienoic derivatives, 20:3Δ5,11,14 and 22:3Δ7,13 16, were found higher in C with respect to other groups, presumably due to the high 18:2n-6 content of this diet.     

Fatty acid metabolism and lipid secretion by perfused livers from rats fed laboratory stock and sucrose-rich diets

To assess the possible role of altered hepatic processing of free fatty acids in dietary sucrose-induced accumulation of triglyceride in the liver and blood plasma, livers from rats fed commercial laboratory stock and high sucrose diets were perfused both with and without oleic acid substrate. Consumption of the sucrose diet exerted a multiplicity of effects on oleic acid metabolism, characterized by decreased conversion to both ketone bodies and carbon dioxide, increased esterification into liver triglyceride, and increased secretion in triglyceride-rich lipoproteins. During the infusion of oleic acid, livers from sucrose-fed rats also exhibited decreased ketogenesis, and increased secretion of triglyceride from endogenous sources. Since oleic acid uptake from the perfusion medium was identical in both groups, the observed effects of sucrose feeding are ascribed to altered rates of intracellular metabolic processes. Mass and radiochemical analyses of perfusate ketone bodies and triglycerides were indicative of greater mobilization of triglycerides from hepatocellular lipid droplets in the livers from sucrose-fed rats. These livers contained more triglyceride and secreted more triglyceride even in the absence of infused oleic acid. In summary, the sucrose-rich diet increased the esterification:oxidation ratio of intracellular free fatty acids derived from both the circulation and endogenous sources within the hepatocyte. In response, secretion of triglyceride-rich lipoproteins by the liver and deposition of triglyceride within the liver were promoted. It is concluded that alterations in the processing of free fatty acids by the liver contribute significantly to the liver and plasma triglyceride accumulation following sucrose consumption.     

Lipid classes and fatty acid composition of rotifers (Brachionus plicatilis) fed two algal diets

Rotifers (Brachionus plicatilis), maintained on baker's yeast, were fed for 24h upon two algal diets, Isochrysis galbana (diet A) and Isochrysis galbana + Nannochloropsis gaditana (diet B). (These algal diets were selected for their potential use as essential fatty acid (EFA) boosters, taking into account the requirements of fish larvae). The effect of these algal diets on total lipid content, lipid classes and fatty acid composition was studied. The total lipid content increased after feeding upon both diets but no significant differences were found between the two types. Neutral lipid and polar lipid contents increased and a positive correlation was observed between the neutral lipids content of rotifers and that of the food supplied. However, the content of polar lipids in rotifers did not depend upon that of the diet. The increase in neutral lipid content was found to be higher in rotifers fed upon diet B, compared to diet A which increased the phospholipid content. Non-enriched rotifers contained only small amounts of polyenoic fatty acids, i.e. 18:3n-6, 18:3n-3, 20:4n-6, 20:5n-3 and 22:6n-3, the contents of which increased significantly by feeding both diets. The EFA composition (20:4n-6, 20:5n-3 and 22:6n-3) of neutral lipids and phopholipids in rotifers reflected the EFA composition of each diet. Diet B-fed rotifers had the highest content in 20:4n-6 and 20:5n-3, whereas rotifers fed diet A and the highest 22:6n-3 content. The mixed diet I. galbana + N. gaditana enhanced substantially the composition of lipid classes i.e. neutral lipids and of n-3 PUFA of rotifers in comparison with Isochrysis or yeast diets.