Makeup of free intracellular amino acids in Cunninghamella elegans growing on media with hydrocarbons]

The rate of growth of Cunninghamella elegans (--) 1204 is higher on a mineral medium with glucose (6.56 g/litre) than on a mineral medium containing undecane, tridecane, and pentadecane (0.72--0.87 g/litre); all glutamic acid is consumed only from the medium with glucose. The cells contain 15--16 free amino acids and 1--2 amides, glutamic and aspartic acids and alanine prevailing. The culture grown on the medium with glucose contains asparagine, and the cells cultivated on the medium with alkanes contain histidine. Non-proteinogenous aminobutyric acids were found in the pool of the cells grown on all tested media with an exception of the medium containing undecane.     

Formation of alcohols during sucrose heating with amino acids]

The formation of alcohols during sucrose heating with amino acids was investigated. The sucrose heating to 180-190 degrees C resulted in the formation of methanol and ethanol and its heating with alanine--propanol and isobutanol. The sucrose heating with phenylalanine led to the formation of beta-phenylethanol as well. Alcohols were identified as benzoates by paper chromatography. They were also identified by infrared spectra.     

Changes of free amino acids in media during the culture of mosquito cells

The utilization of free amino acids in culture media by two mosquito cell lines derived from Aedes aegypti (Peleg, 1969) and Culex molestus (Kitamura, 1970), were studied. Amino acids which showed a marked decrease with increasing period of culture were aspartic acid, cystine, and ornithine in both cell lines. Asparagine and glutamine decreased markedly in Culex cell culture, but only slightly in Aedes cell culture. In contrast isoleucine, leucine, proline, tyrosine and valine decreased more in the Aedes cell culture than in the Culex cell culture. Arginine, glycine, lysine, phenylalanine, serine, threonine and tryptophan did not change significantly in the culture media of either cell lines. α-Alanine increased markedly in the culture of both cell lines. Glutamic acid increased to some extent in the Culex cell culture, but not in the Aedes cell culture. β-Alanine and histidine increased slightly in the Aedes cell culture, whereas they remained almost unchanged in Culex cell culture.     

Lipid composition of Cunninghamella elegans cultivated on n-alkanes]

The ability to oxidize n-alkanes was studied with various species of fungi belonging to the Cunninghamella genus. These fungi are able to assimilate hydrocarbons and to accumulate up to 1.5 g/litre of biomass. The most active strain was Cunninghamella elegans (-) 1204. The amount of lipids formed, and their composition, depended on the length of the carbon chain of oxidized alkane. The content of fat in the cells increased with the length of the hydrocarbon chain. The following lipid fractions have been detected: phospholipids, monoglycerides, diglycerides, triglycerides, sterols, free fatty acids, sterol esters, and hydrocarbons. The qualitative composition of the fractions depended, to a considerable extent, on the n-alkane utilized. Investigation of the fatty-acid composition of intracellular lipids has shown that fatty acids with an even number of carbon atoms are formed from hydrocarbons with an even number of these atoms, while fatty acids both with an even and odd number of carbon atoms are synthesized from hydrocarbons with an odd number of these atoms. The relative content of the acids with the same number of carbon atoms as that of the alkane being utilized increased with the length of the carbon chain.     

Formation of sulfate and glucoside conjugates of benzo[e]pyrene by Cunninghamella elegans

 Benzo[e]pyrene is a pentacyclic aromatic hydrocarbon, which, unlike its structural isomer benzo[a]pyrene, is not a potent carcinogen or mutagen. The metabolism of benzo[e]pyrene was studied using the filamentous fungus Cunninghamella elegans ATCC 36112. C. elegans metabolized 65% of the [9, 10, 11, 12-³H]benzo[e]pyrene and unlabeled benzo[e]pyrene added to Sabouraud dextrose broth cultures after 120 h of incubation. Three major metabolites of benzo[e]pyrene were separated by reversed-phase high-performance liquid chromatography. These metabolites were identified by ¹H and ¹³C NMR, UV-visible, and mass spectral analyses as 3-benzo[e]pyrenylsulfate, 10-hydroxy-3-benzo[e]pyrenyl sulfate, and benzo[e]pyrene 3-O-β-glucopyranoside. Received: 7 September 1995/Received revision: 14 November 1995/Accepted: 11 December 1995     

Compartmental distribution of amino acids during hemodialysis-induced hypoaminoacidemia

The intracellular concentrations of essential amino acids (EAA) in muscle are maintained relatively constant under a variety of conditions. However, the effect of a decrease in blood amino acid concentrations on intracellular concentrations is not clear. Similarly, the relation between intracellular and interstitial concentrations has not been determined in this circumstance. Thus the aim of this study was to determine the effect of hypoaminoacidemia on intracellular, interstitial, and plasma concentrations of EAA and the mechanisms responsible for the respective changes. Twelve normal pigs were investigated before and during 120 min of hemodialysis by use of stable-isotope tracer methodology, microdialysis technique, and muscle biopsies. During hemodialysis, there was a decrease in the interstitial fluid concentrations of phenylalanine, leucine, alanine, and lysine that corresponded to their decrease in plasma concentration. Nonetheless, the intracellular concentrations of these amino acids were maintained at the basal levels throughout the entire period due principally to a reduction in the rate of incorporation of amino acids into protein that was approximately equivalent to the decrease in uptake from the plasma. In conclusion, intracellular concentrations of amino acids are regulated to maintain relatively constant values, even when plasma and interstitial concentrations fall as a consequence of hemodialysis.     

Effect of culture media on the composition of free amino acids in Saccharomyces cerevisiae yeast

The quantitative and qualitative compositions of free amino acids of the yeast Saccharomyces cerevisiae Y-503 cultivated in different nutrient media were studied by liquid chromatography. The yeast grown in the medium containing geothermal water was shown to accumulate more amino acids. During lyophilization, the stabilization of the physiological activity of the yeast in this nutrient medium was observed. The increased biological value of dry yeast was shown to depend on the content of free amino acids, including essential amino acids: arginine, histidine, leucine, isoleucine, lysine, threonine, serine and phenylalanine.     

Effect of energy restriction during late pregnancy on plasma insulin, blood glucose, blood urea and blood free amino acids in pregnant and suckling sheep]

The experiment was carried out in autumn using 27 Limousine ewes during pregnancy and lactation. Some blood essential and non-essential free amino acids increase during late pregnany. Blood glucose, blood urea and blood free threonine, valine and glycine increase after parturition. Reducing the energy supply of the ration during late pregnancy results in a decrease of plasma insulin and blood free tyrosine, phenylalanine and alanine.     

The distribution of free amino acids in subcellular fractions of guinea-pig brain

1. The free amino acids of homogenates of guinea-pig brain in 0.32m-sucrose and of subcellular fractions derived therefrom have been estimated by the method of Moore & Stein. 2. Seven amino acids together accounted for over 80% of the free amino compounds; these are, in decreasing order of abundance: glutamate, aspartate, gamma-aminobutyrate, glycine, serine, alanine and threonine. In addition, there are appreciable quantities of amide (presumably glutamine). 3. Control experiments showed that the pattern of free amino acid occurrence in sucrose homogenates was similar to that of brains of animals killed by freezing in liquid nitrogen and extracted immediately without thawing. 4. The subcellular distribution of the amino acids resembled that of soluble cytoplasmic markers; there was no specific localization in a fraction rich in isolated presynaptic nerve terminals of amino acids capable of exciting or depressing central neurones. 5. The significance of the results is discussed in relation to the possible role of centrally active amino acids as transmitters.