The relationship between freezing resistance and fatty acid composition of yeasts

Abstract The relationship between freezing resistance and cellular long-chain fatty acid composition of 18 selected yeast strains was studied. All strains produced a series of saturated and unsaturated evennumbered fatty acids ranging from 14 to 20 carbons in length. The majority of the freeze-resistant yeasts were found among fermentative species with a content of oleic acid above 40%.     

Differentiation between B. pertussis and B. parapertussis according to their fatty acid composition

The fatty acid composition of 3 B. pertussis strains and 2 B. parapertussis strains grown on casein-carbon agar (CCA) with 8% of sheep blood added and without blood, as well as B. parapertussis strain grown on beef-extract agar (BEA) has been studied by gas chromatography. The fatty acid profiles characteristic of B. pertussis and B. parapertussis were greatly different, as B. parapertussis has a considerable amount of methylene-hexadenocanoic acid, while containing less hexadecenoic and octadecanoic acids and more tetradecanoic acid. The fatty acid composition of 2- to 5-day Bordetella cultures grown on CCA with and without blood has no essential differences. Differences in the content of various fatty acids in B. parapertussis grown on CCA and BEA had no essential influence on the fatty acid profile. The specificity of the fatty acid composition of B. pertussis and B. parapertussis allows to use this characteristics for their differentiation.     

Influence of dietary fatty acid composition on the relationship between CETP activity and plasma lipoproteins in monkeys.

CETP activity, measured as transfer of cholesteryl ester from exogenous HDL to exogenous VLDL and LDL, reflecting CETP mass as determined by ELISA, was documented in three groups of St. Kitts vervet monkeys fed diets enriched in saturated (Sat), monounsaturated (Mono), or n-6 polyunsaturated (Poly) fatty acids. CETP activity was not different when comparing the three dietary fats. However, CETP activity was significantly higher when cholesterol was added to each of the diets. Significant positive associations between CETP activity and VLDL and LDL cholesterol concentrations were found whereas significant negative associations were seen between CETP activity and HDL cholesterol in each of the diet groups. The strength of these associations was highest in the Sat group. Cholesteryl ester (CE) fatty acid composition of lipoproteins varied widely among diet groups, with the more polyunsaturated CE of the Poly group being associated with a higher rate of CE transfer to endogenous acceptor apolipoprotein B-containing lipoproteins. Finally, only the Sat diet group showed significant positive correlations of CETP activity with LDL particle diameter (r = 0.76), cholesteryl ester percentage (r = 0.67), and a strong negative correlation (r = -0.86) with LDL receptor function, estimated as the difference between native and methylated LDL turnover rates. We speculate that strong associations between CETP and LDL metabolism may explain, at least in part, the increased atherogenicity of dietary saturated fat.     

The relationship between the chemical structure of fatty acids and their mycobactericidal activity.

The bactericidal activity of long-chain fatty acids on mycobacteria was examined by exposing the organisms to these acids at 0.04 mM in 0.05 M acetate buffer (pH 5.6). The lethal effect of saturated fatty acids was related to the chain-length of hydrocarbon, C14:0 being the strongest in the activity and longer and shorter fatty acids being less active. Unsaturation, isomerism and the presence of alpha-hydroxy group were found to be other factors governing the activity. The lethal effect was greater in the order of C18:3 greater than C18:2 greater than C18:1(cis) greater than C18:1(trans) greater than alpha-OH C18:0 greater than C18:0. C20:4 was placed between C18:3 and C18:2 in this respect. Esterification of C14:0, C18:1 and C20:4 to methyl esters and cholesteryl esters abolished completely the bactericidal activity of these acids, suggesting the requirement of carboxyl group for the activity. The relationship between the fatty acid structure and the lethal effect was discussed in reference to these observations.     

The relationship between carbohydrate composition of some tree seeds and their longevity

Fresh mature tree seeds of 16 species plus soybean were usedfor the analysis of soluble neutral sugar content, as well asfor the determination of longevity in terms of the time requiredfor the seeds to decrease to 50% of the original germinationunder 5C and 80–91% relative humidity. Oligosaccharideswere sometimes found in species of recalcitrant; although themass ratio of oligosaccharide/total sugar or mole ratio of stachyoseand raffinose/sucrose was less than 0.05 or 0.044, respectively.The time required for seeds to decrease to 50% germination variedfrom a few days to 8.3 months for the seeds of desiccation-sensitivespecies. The low ratio of oligosaccharide to sucrose is, however,most unlikely to be a cause of short life-span in recalcitrantseeds. It is suggested that 0.05 mole of oligosaccharide needs to beassociated with one mole sucrose to confer the seeds with desiccationtolerance. Orthodox seeds which have a high ratio of oligosaccharide/totalsugars happened to have a low ratio of disaccharide/total sugarindicating active biosynthetic activity of oligosaccharide.There was a positive correlation between the longevity and themass ratio of oligosaccharide/total sugar or oligo-/disaccharidefor those desiccation-tolerant seeds tested. These results supportthe conclusion that the ratio of oligo-/disaccharide plays arole in the desiccation tolerance and, consequently, the longevityof orthodox seeds. Key words: Tree seed, storage behaviour, recalcitrant, soluble carbohydrate, oligosaccharide, seed longevity     

Dietary gamma-linolenic acid dose-dependently modifies fatty acid composition and immune parameters in rats.

gamma-linolenic acid (GLA) has been reported to improve several inflammatory disorders through regulation of eicosanoid production. However, since GLA is a precursor of arachidonic acid, it may bring about increasing tissue arachidonic acid levels with subsequent pro-inflammatory events. To explore this possibility, we examined the effect of high-dose GLA acid on the fatty acid profile of immune cells, leukotriene B4 production by peritoneal exudate cells and immunoglobulin productivity of mesenteric lymph node lymphocytes of Sprague-Dawley rats. Male rats were fed 10% fat diets containing graded levels, 0, 20, 40 and 60% of GLA for 3 weeks. The results showed the distinction in activity of metabolizing GLA between immune cells and liver. Thus, in immune cells such as mesenteric lymph node and spleen lymphocytes and peritoneal exudate cells, more dihomo-gamma-linolenic acid was found than in the liver. Leukotriene B4 production by peritoneal exudate cells was significantly suppressed when fed the highest level of GLA suggesting a lower risk of allergic reaction. Moreover, immunoglobulin productivity in mesenteric lymph node lymphocytes was promoted by dietary GLA. The present study indicates that a high dose of GLA may exert anti-inflammatory effects through suppression of leukotriene B4 release and strengthening of gut immune system, thus ameliorating allergic reaction.     

The relationship between schizophrenia and essential fatty acid and eicosanoid metabolism.

Essential fatty acids (EFAs) and their eicosanoid derivatives are important constituents of the brain and regulators of neuronal function. There is direct and indirect evidence of impaired metabolism of prostaglandin (PG)E1 in schizophrenia. There is also direct evidence of abnormal EFA biochemistry with plasma phospholipids from five populations and brain phospholipids from another all showing reduced levels of linoleic acid and elevated levels of 22-carbon EFAs of both n-6 and n-3 series. Clinical trials of PGE1 and of the PGE1 precursors, gamma-linolenic acid (GLA) and dihomo-gamma-linolenic acid (DGLA) have shown modest therapeutic effects. In view of lack of therapeutic process involving drugs based on the dopamine concept of schizophrenia, it is time for new approaches based on the EFA/PG concept to be evaluated thoroughly.     

Studies of the relationship between adenosine deaminase and immune function.

The relationship between adenosine deaminase deficiency and immunologic responsiveness was studied in mice treated in vivo with deoxycoformycin to produce very low levels of adenosine deaminase activity in tissues. Effects of such treatment on thymocyte response to concanavalin A in vitro and on mixed cultures of splenic cells were determined. Under the conditions used, inhibition of adenosine deaminase by deoxycoformycin had no effect on the viability or responsiveness of either thymocytes or splenic cells.     

Human fetal and adult spleen phospholipids and their fatty acid composition

Total phospholipid contents and the individual phospholipid components of human adult and fetal spleens from 17--18 and 23--24 week's pregnancies composition of sphingomyelin, phosphatidylcholine, phosphatidylethanolamine, phosphatidylinositol, phosphatidylserine, diphosphatidylglycerol and phosphatidic acid studied in human adult, 17--18 and 23--24 week fetal spleens.     

Yeast fatty acid synthase: structure to function relationship

The yeast fatty acid synthase is a multifunctional enzyme composed of two nonidentical subunits in an alpha 6 beta 6 complex that is active in synthesizing fatty acids. The seven catalytic activities required for fatty acid synthesis are divided between the alpha and beta subunits such that the alpha 6 beta 6 complex has six complements of each activity. It has been proposed that these are organized into six centers for fatty acid synthesis. There are different opinions regarding the operation of these centers in the alpha 6 beta 6 complex, on view being that they are functionally independent and the other proposes half-sites activity for the complex. We have attempted to distinguish between these proposals by the most direct method of active site titration, i.e., quantitation of fatty acyl product in the absence of turnover. This was accomplished by using p-nitrophenyl thioacetate and thiophenyl malonate (in place of the coenzyme A analogues) as substrates along with NADPH, thereby depriving the yeast synthase of coenzyme A required to release product as fatty acyl coenzyme A. The amount of fatty acyl product formed was quantitated by gas-liquid chromatography, as well as by direct estimation of radioactivity in the product when p-nitrophenyl thio [1-14C] acetate was used as a substrate. In both cases, a stoichiometry of close to six was found for mole of fatty acid synthesized per mole of alpha 6 beta 6 complex. This indicates that there are six functional centers for fatty acid synthesis in the multifunctional yeast alpha 6 beta 6 fatty acid synthase and that these centers operate independently.(ABSTRACT TRUNCATED AT 250 WORDS)     

The fatty acid composition of leech lipids

• 1.1. The constituent fatty acids of the neutral and phospholipids of Macrobdella ditetra, Nephelopsis obscura, Philobdella gracilis and Hirudo medicinalis have been determined.
• 2.2. Unsaturated fatty acids predominated in both neutral and phospholipid fractions of all leech species examined.
• 3.3. Arachidonic acid (20:4) was the most prevalent fatty acid in all species, accounting for as much as 36.7% of the total phospholipid fatty acids.