Longevity, lipids and C. elegans

There are four types of fatty acids but only two types are essential nutritional requirements for many animals. These are the omega-6 polyunsaturated fatty acids (n-6 PUFA) and the omega-3 polyunsaturated fatty acids (n-3 PUFA) and because they cannot be converted to one another they are separate essential dietary requirements. They are only required in small amounts in the diet and their biological importance stems largely from their role as constituents of membrane lipids. They are synthesised by plants and, as a generalisation, green leaves are the source of n-3 PUFA while seeds are the source of n-6 PUFA in the food chain. While the fatty acid composition of storage fats (triglycerides) is strongly influenced by dietary fatty acid composition, this is not the case for membrane fats. The fatty acid composition of membrane lipids is relatively unresponsive to dietary fatty acid composition, although n-3 PUFA and n-6 PUFA can substitute for each in membrane lipids to some extent. Membrane fatty acid composition appears to be regulated and specific for different species. The role of essential fats in the diet of animals on (1) basal metabolic rate, (2) thermoregulation, (3) maximum longevity, and (4) exercise performance is discussed.

This study was conducted to: (1) determine the effects of stocking density and dietary protein:energy ratio on survival, growth, feed consumption, feed conversion, lipo-somatic index, dress-out percentage, and productive protein value of common snapping turtles; and (2) determine the fatty acid composition of muscle, liver, and fat bodies of wild common snapping turtles and common snapping turtles fed a diet of known fatty acid composition. Hatchling common snapping turtles, Chelydra serpentina, were stocked at five or 10 animals per container (29 and 58 turtles/m$\sp2$, respectively), and fed one of seven prepared diets. Six diets contained 30, 35, or 40% protein at two digestible energy levels (7 or 9 kcal DE/g protein). The seventh was a reference diet (66% protein and 5 kcal DE/g protein) formulated to equal or exceed the whole-body essential amino acid composition of wild, common snapping turtles. Hatchling turtles were fed a formulated feed of known fatty acid composition, analyzed for tissue fatty acids, and compared to the fatty acid composition from muscle, liver, and depot fat from wild, adult turtles. Hatchling turtles stocked at 58 turtles/m$\sp2$ exhibited greater mortality (P = 0.026), less weight gain (P = 0.079), and lower lipo-somatic index (P = 0.004) than turtles stocked at 29 turtles/m$\sp2$. Turtles fed the reference diet achieved greater weight gain, higher whole-body protein, and higher percentage whole-body protein than those fed the other diets (P $<$ 0.001). The increased growth of turtles fed the reference diet indicated that the protein (amino acid) content and/or energy:protein ratio of the reference diet was responsible for the increased growth compared to other diets. The fatty acid composition of lipid from tissues of the hatchling turtles fed the alligator feed reflected dietary fatty acid composition. The fatty acid composition of whole-lipid, polar lipid, and nonpolar lipid of muscle, and fat bodies of common snapping turtles fed alligator feed exhibited the greatest variability; liver polar lipids exhibited the least variability when compared to wild turtles. Studies to determine optimum tissue fatty acid composition of adult and juvenile common snapping turtles and minimum dietary fatty acid and protein:energy requirements for optimum growth and reproductive success should be undertaken.

Comparative study of the fatty acids in human dental plaques and whole saliva

Are mycoplasma membrane proteins affected by variations in membrane fatty acid composition?

Over the past 100 years, changes in the food supply in Western nations have resulted in alterations in dietary fatty acid consumption, leading to a dramatic increase in the ratio of omega-6 (omega6) to omega3 polyunsaturated fatty acids (PUFA) in circulation and in tissues. Increased omega6/omega3 ratios are hypothesized to increase inflammatory mediator production, leading to higher incidence of inflammatory diseases, and may impact inflammatory gene expression. To determine the effect of reducing the omega6/omega3 ratio on expression of inflammatory pathway genes in mononuclear cells, healthy humans were placed on a controlled diet for 1 week, then given fish oil and borage oil for an additional 4 weeks. Serum and neutrophil fatty acid composition and ex vivo leukotriene B(4) production from stimulated neutrophils were measured at the start and end of the supplementation period and after a 2-week washout. RNA was isolated from mononuclear cells and expression of PI3K, Akt, NFkappaB, and inflammatory cytokines was measured by real-time PCR. A marked increase was seen in serum and neutrophil levels of long-chain omega3 PUFA concomitant with a reduction in the omega6/omega3 PUFA ratio (40%). The ex vivo capacity of stimulated neutrophils to produce leukotriene B(4) was decreased by 31%. Expression of PI3Kalpha and PI3Kgamma and the quantity of PI3Kalpha protein in mononuclear cells was reduced after supplementation, as was the expression of several proinflammatory cytokines. These data reveal that PUFA may exert their clinical effects via their capacity to regulate the expression of signal transduction genes and genes for proinflammatory cytokines.

ABSTRACT. Growth of Acanthamoeba castellanii in batch culture at 30° C was associated with marked changes in cellular fatty acid composition. The largest change occurred in the linoleate to oleate ratio, which was maximal in early‐ to mid‐exponential phase cultures but decreased approximately 10‐fold as cells approached stationary phase. The higher degree of lipid unsaturation in young cultures was accentuated by a greater proportion of 20‐carbon polyunsaturated fatty acids than in stationary phase cultures. The unsaturation index (average number of double bonds per fatty acid) was maximal in mid‐exponential phase cultures after 24 hours growth. Incorporation of [1‐14C]acetate into polyunsaturated fatty acids in short‐term (2 hour) experiments was high in 12 and 24 hour old cultures, where linoleate and eicosadienoate accounted for up to 26% of total labelled fatty acids. Incorporation of [1‐14CJacetate into these fatty acids was negligible in stationary phase cultures. These results were correlated with changes in the specific activity of the Δ12‐desaturase. Δ12‐Desaturase activity was greatest in microsomal membranes isolated from early‐ to mid‐exponential phase cells, but declined by approximately 50% as cultures progressed towards stationary phase. Membrane fractionation studies revealed that although some differences in fatty acid composition between plasma‐membrane, mitochondrial (enriched), and microsomal membrane fractions were evident, the large changes in lipid unsaturation in whole cells of A. castellanii could not be accounted for by differential development of particular subcellular membranes.

Stearoyl‐CoA desaturase activity and the fatty acid composition of lipids of adipose tissue and liver were determined in 35‐ and 180‐day‐old cardiomyopathic hamsters and age‐matched normal controls. Enzyme activity was unchanged in the adipose tissue of 35‐day‐old animals but was significantly depressed in the 180‐day‐old cardiomyopathic hamsters. In the liver, stearoyl‐CoA desaturase activity was significantly lower in the 35‐day‐old disease animals but was unchanged in the 180‐day‐old animals. The analysis of the fatty acid composition of the lipids isolated from adipose tissue showed an increase in the relative percentage of saturated fatty acids accompanied by a decrease in the relative percentage of unsaturated fatty acids in both age groups of the cardiomyopathic hamsters. However, linoleic acid content was increased in the diseased animals. Similar changes in fatty acid composition of lipids from the livers of 35‐day‐old cardiomyopathic hamsters were observed, but no significant differences in the fatty acid composition between 180‐day‐old cardiomyopathic hamsters and normal controls were observed. The changes in the fatty acid composition appear to be related to the observed changes in desaturase activity. In is concluded that such changes in desaturase activity and fatty acid composition could affect the normal structure and functions of membranes and membrane‐related processes.

Fatty acids, as key components of cellular membranes and complex lipids, may play a central role in endocrine signalling and the function of adipose tissue and liver. Thus, the lipid fatty acid composition may play a role in health status in the equine. This study aimed to investigate the fatty acid composition of different tissues and liver lipid classes by comparing Warmblood horses and Shetland ponies under defined conditions. We hypothesized that ponies show different lipid patterns than horses in adipose tissue, liver and plasma. Six Warmblood horses and six Shetland ponies were housed and fed under identical conditions. Tissue and blood sampling were performed following a standardized protocol. A one-step lipid extraction, methylation and trans-esterification method with subsequent gas chromatography was used to analyse the total lipid content and fatty acid profile of retroperitoneal, mesocolon and subcutaneous adipose tissue, liver and plasma. Fatty acids were grouped according to their degree of saturation and their conjugated double bond into the respective lipid classes. In the adipose tissues, saturated fatty acids (SFAs) and n-9 monounsaturated fatty acids (n-9 MUFAs) were most present in ponies and horses. N-6 polyunsaturated fatty acids (n-6 PUFAs), followed by SFAs, were most frequently found in liver tissue and plasma in all animals. Horses, in comparison to ponies, had significantly higher n-6 PUFA levels in all tissues and plasma. In liver tissue, horses had significantly lower hepatic iso-branched-chain fatty acids (iso-BCFAs) than ponies. The hepatic fatty acid composition of selected lipid classes was different between horses and ponies. In the polar PL fraction, horses had low n-9 MUFA and n-3 PUFA contents but higher n-6 PUFA contents than ponies. Furthermore, iso-BCFAs are absent in several hepatic lipid fractions of horses but not ponies. The differences in fatty acid lipid classes between horses and ponies provide key information on the species- and location-specific regulation of FA metabolism, thus affecting health status such as inflammatory responses.

The influence of insufficient watering and a melamine salt of bis(oxymethyl)-phosphonic acid (melaphen) on fatty acid composition of mitochondrial membrane of pea seedlings has been studied. It is shown that insufficient watering results in a 1.57-fold decrease in the ratio of unsaturated to saturated C18 fatty acids and in a 3.04-fold decrease in the ratio of unsaturated to saturated C20 fatty acids. The modification of fatty acid composition of mitochondrial membranes was associated with the alterations in their functional state: maximal rates of oxidation of NAD-dependent substrates and the rates of electron transport at the end of respiratory chain decreased. A preliminary treatment of the seeds with 3 × 10−9 M melaphen restored the maximal rates of oxidation of NAD-dependent substrates to the control values. We suggest that the alterations of the electron transport rates in respiratory chain in mitochondria are related to the physicochemical state of the membranes of these organelles, as the treatment with melaphen prevented the changes in fatty acid composition of the membranes of seedlings growing under the conditions of insufficient watering.

Membrane compositions, particularly of mitochondria, could be critical factors in the mechanisms of growth and aging processes, especially during phases of high oxidative stress that result in molecular damage. In the present study, liver and mitochondrial membrane phospholipid (PL) compositions were analyzed in rainbow trout during its four first years of life, a period characterized by rapid growth and high oxidative stress. Specifically, farmed fish of three ages (1-, 2- and 4-years) were studied, and PL compositions of whole liver and liver mitochondria, and fatty acid compositions of individual PL classes were determined. Liver mitochondrial membranes showed a PL composition different to that of the whole tissue suggesting adaptation of cell and subcellular membranes to specific functions. Individual PL had characteristic fatty acid compositions that were similar in whole liver and mitochondrial membranes. Whole liver and mitochondria showed increased lipid peroxidation with age along with changes in membrane PL fatty acid compositions. Most PL classes showed similar changes in fatty acid composition among the age groups, with reduced proportions of docosahexaenoic acid (DHA) and, generally, concomitantly increased levels of monounsaturated fatty acids, which together resulted in reduced peroxidation index (PIn). However, total polyunsaturated fatty acid (PUFA) content did not change significantly with age due to increased eicosapentaenoic acid, docosapentaenoic acid and, in most PL, increased n-6 PUFA. These results suggest there may be oxidation of PL DHA with compensatory mechanisms to maintain membrane fluidity and function. However, modification of fatty acid composition of specific PLs, such as cardiolipin, could affect the electron transport chain efficiency and propagate the oxidative reaction throughout the cell. In addition, both the content and fatty acid composition of sphingomyelin, which has been suggested as a possible mediator of cell dysfunction and apoptosis, changed with age differently to the other PL classes. Moreover, these changes showed different trends between mitochondria and whole liver. These data suggest there is marked oxidative stress associated with rapid growth and maturation in rainbow trout. Changes observed in membrane lipids point to their possible participation in the processes involved in this species response to oxidative stress and damage accumulation rate.

Here we show that in vitro supplementation of L1210 murine lymphoblastic leukaemia cells with n-3 polyunsaturated fatty acids results in considerable changes in the fatty acid composition of membrane phospholipids. Incubations for 48 h with 30 microM eicosapentaenoic acid (20:5, n-3; EPA) or docosahexaenoic acid (22:6, n-3; DHA) results primarily in substitution of long chain n-6 fatty acids with long-chain n-3 fatty acids. This results in a decrease in the n-6/n-3 ratio from 6.9 in unsupplemented cultures to 1.2 or 1.6 for EPA and DHA supplemented cultures, respectively. Coincident with these changes in membrane fatty acid composition, we observed a 5-fold increase in the rate of adenosine (5 microM) uptake via a nitrobenzylthioinosine (NBMPR)-sensitive nucleoside transporter in EPA- and DHA-supplemented L1210 cells, relative to unsupplemented cells. This seemed to result from a decrease in the Km for adenosine from 12.5 microM in unsupplemented cultures to 5.1 microM in DHA-treated cultures. Guanosine (50 microM) transport was similarly affected by DHA with a 3.5-fold increase in the initial rate of uptake. In contrast, pyrimidine transport, as measured by uptake of thymidine and cytidine, was not similarly affected, suggesting that substrate recognition had been altered by fatty acid supplementation. Studies using [(3)H]NBMPR showed that there was no effect of EPA or DHA on either the number of NBMPR-binding sites or the affinity of these sites for NBMPR. This observation suggests that the increases in adenosine and guanosine transport were not due to increases in the number of transported sites but rather that EPA and DHA directly or indirectly modulate transporter function.

To investigate the nutritional composition of fatty acids in freshwater products in Hunan Province. The edible parts of freshwater products were detected by gas chromatography, and fatty acid fingerprints were obtained by statistical analysis. A total of 18 freshwater products were monitored and 14-26 fatty acids were detected in each freshwater product. Among them, 12 were saturated fatty acids(SFA), ranging from 0. 74 to 3143 mg/100 g, 9 were monounsaturated fatty acids(MUFA), ranging from 1. 23 to 2790 mg/100 g, and 10 were polyunsaturated fatty acids(PUFA), ranging from 1. 75 to 2832 mg/100 g. The ratio of n-6 to n-3 in polyunsaturated fatty acids ranged from 0. 24∶1 to 15. 7∶1. The composition of fatty acids in freshwater products in Hunan Province is mainly unsaturated fatty acids. Most freshwater products are rich in n-3 PUFA, and the ratio of n-6 PUFA to n-3 PUFA is less than 6, which is beneficial to the nutritional balance. The composition and content of fatty acids have ideal nutritional value.

Alteration in the membrane fatty acid composition of human lymphocytes and cultured transformed cells induced by interferon

The type of dietary fat affects the action of insulin by changes induced in the fatty acid composition of cell membranes. Little is known, however, about the effects of dietary fatty acids on insulin secretion or the possible relation between the fatty acid composition of the membrane phospholipids and insulin secretion. We therefore studied the effects of dietary fatty acids on insulin secretion stimulated by glucose, forskolin and arginine, and on the insulin content of isolated pancreatic islets, as well as on the fatty acid composition of muscle phospholipids, which were used as markers of the diet-induced modifications in the cell membranes. Five groups of rats were fed for one month with diets varying only in their fat composition: olive oil, sunflower oil, soybean oil, fish oil and palmitic acid (16:0) + soybean oil (SAT). The SAT group had higher insulin secretion, independently of the secretagogue used. No significant differences were found in insulin content between the groups. The dietary fatty acids modified the fatty acid composition of the muscle phospholipids, both in endogenously synthesized fatty acids and in those which were unable to be synthesized by the organism. No statistically significant relation was found between insulin secretion and the content of certain fatty acids in the muscle phospholipids.

The most complete analyses of fatty acids have been obtained on total lipid extracts, although a prior separation into neutral and polar lipids has also been common. In many instances, the total fatty acid esters have been subjected to a preliminary segregation into subclasses based on unsaturation, molecular weight, and the presence or absence of functional groups. The final composition of the fatty acids in the neutral and polar lipids is then derived by normalization of the data. Detailed analyses of the total fatty acid composition of a lipid have proved essential for obtaining a complete account of the molecular species of various glycerolipids which otherwise might have been overlooked because of losses at intermediate stages of fractionation. Truly meaningful comparisons of the fatty acid composition of tissue lipids are obtained only by the examination of individual lipid classes and molecular species in specific cellular fractions. There has been a steady increase in these data, and those applying to the neutral acylglycerols have been extensively documented in other chapters of this volume.