scholarly journals The metabolism of cholesterol in the presence of liver mitochondria from normal and thyroxine-treated rats

1965 ◽  
Vol 94 (3) ◽  
pp. 594-603 ◽  
Author(s):  
KA Mitropoulos ◽  
NB Myant
Keyword(s):  
Carbon Dioxide ◽  
Steam Distillation ◽  
Liver Mitochondria ◽  
Incubation Mixture ◽  
Side Chain ◽  
Volatile Fraction ◽  
Low Molecular Weight ◽  
Butanol Extract ◽  
Rate Limiting ◽  
Layer Chromatography

1. [26-(14)C]- and [4-(14)C]-Cholesterol were incubated with liver mitochondria from normal and thyroxine-treated rats, and the radioactivity was measured in the carbon dioxide evolved during the incubation, in a butanol extract of the incubation mixture and in a volatile fraction containing substances of low molecular weight derived from the side chain of cholesterol. The butanol extract was separated by paper chromatography into three radioactive fractions, one of which contained the steroids more polar than cholesterol. 2. The butanol extract from incubations with [4-(14)C]cholesterol contained a radioactive substance moving with the same R(F) as cholic acid on thin-layer chromatography. 3. After incubation with [26-(14)C]-cholesterol, 60-80% of the radioactivity extracted by steam-distillation of the incubation mixture at acid pH was recovered as [(14)C]propionic acid. 4. In the presence of [26-(14)C]cholesterol, mitochondria from thyroxine-treated rats produced more radioactivity in carbon dioxide and in the volatile fraction, and less radioactivity in the fraction containing the polar steroids, than did mitochondria from normal rats. In the presence of [4-(14)C]cholesterol, mitochondria from thyroxine-treated rats produced the same amount of radioactivity in the polar steroids as did normal mitochondria. 5. Thyroxine treatment had no effect on the capacity of the mitochondria to oxidize propionate to carbon dioxide. 6. These results are best explained by supposing that thyroxine stimulates a rate-limiting reaction leading to the cleavage of the side chain of cholesterol, but has little or no influence on the hydroxylations of the ring system or on the oxidation of the C(3) fragment removed from the side chain.

scholarly journals Volatile Constituents of Trifolium Pratense and T. Repens from N.E. Italian Alpine Pastures

2009 ◽  
Vol 4 (6) ◽  
pp. 1934578X0900400 ◽  
Author(s):  
Aldo Tava ◽  
Daniele Ramella ◽  
Maris Grecchi ◽  
Paolo Aceto ◽  
Renato Paoletti ◽  
...  
Keyword(s):  
Steam Distillation ◽  
Trifolium Pratense ◽  
Red Clover ◽  
Volatile Oil ◽  
Volatile Fraction ◽  
Fresh Weight ◽  
Fresh Weight Basis ◽  
Qualitative And Quantitative ◽  
Aerial Parts ◽  
Trifolium Pratense L

The composition of the volatile fraction of two important forage legumes from Italian sub-alpine N.E. pastureland, namely Trifolium pratense L. subsp. pratense (red clover) and T. repens subsp. repens (white clover) were investigated. The volatile oil was obtained from the fresh aerial parts by steam distillation and analyzed by GC/FID and GC/MS. The oil yield was 0.018 and 0.021% (weight/fresh weight basis) for T. pratense and T. repens, respectively. Several classes of compounds were found in both the oils, including alcohols, aldehydes, ketones, terpenes, esters, hydrocarbons, phenolics and acids. Qualitative and quantitative differences were found.

scholarly journals Uric Acid Is a Genuine Metabolite of Penicillium cyclopium and Stimulates the Expression of Alkaloid Biosynthesis in This Fungus

2002 ◽  
Vol 68 (4) ◽  
pp. 1524-1533 ◽  
Author(s):  
Florian Helbig ◽  
Jörg Steighardt ◽  
Werner Roos
Keyword(s):  
Uric Acid ◽  
Low Molecular Weight ◽  
Alkaloid Production ◽  
Alkaloid Biosynthesis ◽  
Penicillium Cyclopium ◽  
Measurable Activity ◽  
Reduced Rate ◽  
Rate Limiting

ABSTRACT On searching for endogenous, low-molecular-weight effectors of benzodiazepine alkaloid biosynthesis in Penicillium cyclopium uric acid was isolated from ethanolic or autoclaved mycelial extracts of this fungus. The isolation was based on a three-step high-pressure liquid chromatography procedure guided by a microplate bioassay, and uric acid was identified by mass spectrometry and the uricase reaction. Conidiospore suspensions that were treated with this compound during the early phase of outgrowth developed emerged cultures with an enhanced rate of alkaloid production. Uric acid treatment did not increase the in vitro measurable activity of the rate-limiting biosynthetic enzyme, cyclopeptine synthetase. However, these cultures displayed a reduced rate of uptake of the alkaloid precursor l-phenylalanine into the vacuoles of the hyphal cells as assayed in situ. It is suggested that the depressed capacity of vacuolar uptake caused by the contact of outgrowing spores with uric acid liberated from hyphal cells results in an enhanced availability of the precursor l-phenylalanine in the cytoplasm and thus accounts at least in part for the increase in alkaloid production.

Carbon dioxide excretion in fishes

1986 ◽  
Vol 64 (3) ◽  
pp. 565-572 ◽  
Author(s):  
S. F. Perry
Keyword(s):  
Carbon Dioxide ◽  
Minor Amount ◽  
Acid Base ◽  
Plasma Bicarbonate ◽  
Convective Processes ◽  
Adrenergic Control ◽  
And Control ◽  
The Relationship ◽  
Rate Limiting ◽  
Subsequent Diffusion

The pattern and control of carbon dioxide excretion in fish is reviewed with particular emphasis on the site(s) of bicarbonate dehydration, the involvement of diffusive and convective processes, and the relationship with ionic and acid–base regulation. The principal route for carbon dioxide excretion in fish involves the catalysed dehydration of plasma bicarbonate within erythrocytes to form physically dissolved CO2 and the subsequent diffusion of physically dissolved CO2 across the gill epithelium. It is likely that bicarbonate entry into the erythrocyte in exchange for intracellular chloride, rather than branchial CO2 diffusion or blood/water convection, is the rate-limiting process in carbon dioxide excretion, although a change in any one of these factors will affect overall CO2 elimination. Additionally, a relatively minor amount of CO2 is hydrated within gill epithelial cells to form H+ and HCO3− ions that are exchanged for Cl− ions and Na+ ions, respectively. Evidence is presented indicating that branchial and erythrocytic HCO3−/Cl− exchanges are under adrenergic control and that modulations of these processes by elevated levels of circulating catecholamines may be important in regulating acid–base disturbances.

Spectrophotometric Characterization of Some Authentic Oil of Bergamot and a Few Related Oils

1964 ◽  
Vol 47 (4) ◽  
pp. 611-617
Author(s):  
Felice A Rotondaro
Keyword(s):  
Uv Irradiation ◽  
Steam Distillation ◽  
Uv Absorption ◽  
Volatile Fraction ◽  
Ir Absorption ◽  
Successful Work ◽  
Bergamot Oil

Abstract Steam distillation separates oil of bergamot into a volatile fraction (85—95% of the original pressed oil) which has a qualitatively significant IR absorption but no appreciable UV absorption in the 270—375 mμ, range. The relatively small steam nonvolatile fraction, however, has significant absorption in the 270—375 mμ range; maximum at 313 mμ, minimum at 277 mμ, and a ratio of 2.45 ± 0.07 for A313/A277. The steam nonvolatile fraction of bergamot consists primarily of the furocoumarin bergaptene. These compounds classed as psoralens have been reported to induce sensitization of the skin under the influence of sunlight or UV irradiation. Initial studies to separate bergamot oil constituents from mixtures have been partially successful. Work on commercial mixtures, and on characterizing the nonvolatile fraction by chemical and physical means, will be continued.

Phosphatidylethanolamine in Liver Mitochondria and Endoplasmic Reticulum; Molecular Species Distribution and Turnover

1975 ◽  
Vol 53 (6) ◽  
pp. 698-705 ◽  
Author(s):  
J. G. Parkes ◽  
W. Thompson
Keyword(s):  
Endoplasmic Reticulum ◽  
Fatty Acid ◽  
Specific Activity ◽  
Liver Mitochondria ◽  
Relative Activity ◽  
Layer Chromatography ◽  
Kinetics Of ◽  
Fatty Acid Compositions

Phosphatidylethanolamine from mitochondria and microsomes of guinea pig liver was separated by thin-layer chromatography into eight different classes differing in degree of unsaturation. The fatty acid compositions and molar proportions of each class isolated from microsomes were very similar to the corresponding class in mitochondria. In both organelles about half of the total was dienoic species while tetraenes comprised approximately 20%. Stearic acid was the major saturated fatty acid and in each membrane a greater selectivity for stearate over palmitate was found in each sub-class of phosphatidylethanolamine, when compared with the corresponding class of phosphatidylcholine.Following the intraperitoneal injection of [2-3H]glycerol, the labelling of each molecular class of phosphatidylethanolamine showed very similar progressions in microsomes and mitochondria over a 3 h interval. In both organelles the highest relative specific activity was attained by penta-plus hexaenoic classes, while the large dienoic class had the lowest relative activity, which, however, increased with time. Analysis of the dienoic class of phosphatidylethanolamine from whole liver showed it to be constituted by a rapidly turning over palmitoyl–linoleoyl fraction and a slowly labelled stearoyl–linoleoyl fraction, a pattern also exhibited by dienoic phosphatidylcholines.The similarities in profile of molecular classes of phosphatidylethanolamine and in the kinetics of labelling in vivo point to a close metabolic relation between the lipids of both organelles, suggestive of a transfer of different molecular classes at comparable rates from the endoplasmic reticulum, the site of synthesis, to the mitochondria. This is consistent with numerous other studies in vitro that have demonstrated inter-organelle exchange of lipids.

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