Einfluss der Temperatur auf den Vitamin-C-Gehalt während des Wachstums von englischem Spinat (Rumex patientia L.)

Summary Growth and ascorbic acid content of English spinach (Rumex patientia L.) were determined during a period of 7 weeks in the phytotron and also in the open field in relation to temperature. As compared with constant warm temperature, a low average temperature in the phytotron resulted in significantly increased plant weights and increased ascorbic acid contents. The results of the open field studies showed great deviations in plant weight and ascorbic acid content, due to metereological conditions. Generally, the content of ascorbic acid in spinach increased with the growth of the plants.     

Ascorbic acid in brown adipose tissue: effect of cold acclimation and high intake of the vitamin

Summary The ascorbic acid content of brown adipose tissue increased 62% when rats underwent cold acclimation; however, the increase was 126% when rats living in the cold were fed a basal diet supplemented with 2% ascorbic acid. These findings suggest a role for ascorbic acid in this tissue during nonshivering thermogenesis.Bureau of Nutritional Sciences, publication No. 113.     

In vivo voltametric measurement of ascorbic acid and DOPAC in the striatum of the rat and guinea-pig

Differential pulse voltammetry was performed with electrochemically treated carbon fiber electrodes. By this technique, ascorbic acid and catechol compounds were resolved in vitro in two distinct peaks. Similar oxidation peaks were obtained in vivo from the striatum of Rats and Guinea-Pigs. From electrochemical and pharmacological observations it is suggested that they correspond to the oxidation of extracellular ascorbic acid and 3,4-dihydroxyphenyl acetic acid (DOPAC).     

Biosynthesis of ascorbic acid in chick embryos

Biosynthesis of ascorbic acid was found in the kidneys (mesonephros and metanephros) of the chick embryo as well as in the yolk sac membrane. The activity of L-gulonolactone oxidase in the yolk sac membrane suggested that it was the major source of ascorbic acid in the chick embryo.     

Die Wirkung der Askorbinsäure auf die Katalaseinduktion in Mikroorganismenkulturen

Summary Catalase activity ofStaphylococcus aureus increases the effect of ascorbic acid. Namely the ascorbic acid decreases the dissolved oxygen content of the medium, and low oxygen tension is the natural inducer of catalase synthesis.     

Wirkung der Adrenalektomie und Desoxycorticosteronbehandlung auf die Ascorbinämie und Ascorbinurie der Katze

Summary Two cats were adrenalectomized and kept healthy with daily injections of desoxycorticosterone acetate. The ascorbic acid concentration of blood and urine remained the same as in normal controls. When Dexoxy-corticosterone was omitted, a crisis ensued but the blood and urine concentration of ascorbic acid did not decrease.     

Primitive actimoterigian fishes can synthesize ascorbic acid

Amphibians and reptiles evolved with the capacity to synthesize ascorbic acid. Some higher vertebrates, like bats, guinea pigs, primates, and humans have lost the microsomal enzyme gulonolactone oxidase, and in cases of ascorbic acid deficiency suffer from symptoms of scurvy. The question of whether the capacity to synthesize ascorbate is also present in lower vertebrates could throw light on the evolution of this pathway. In order to find out whether ascorbic acid synthesis took place in two primitive Actinopterigian fish, the paddlefish (Polydon spathula) and the white sturgeon (Acipenser transmontanus) were fed with a scorbutogenic diet or diet(s) supplemented with a graded level of ascorbic acid. We found no growth depression nor external symptoms of scurvy, which would be pronounced in modern bony fishes (Teleostei) under similar conditions. The tissue level of ascorbate in both these primitive species indicated that vitamin C in intestine and liver is not depleted when fed a scorbutogenic diet. Gulonolactone oxidase activity was found in the kineys of the Actinopterigian fishes. Thus, I question the accepted evolutionary pathway for ascorbic acid biosynthesis in lower vertebrates and suggest that the modern bony fishes,Teleostei, lost their ability to express the gulonolactone oxidase genes after they had separated during the Silurian from their common ancestor with the coelacanths (Latimeria) and Dipnoi.     

Ascorbic acid content of neotropical plant parts available to wild monkeys and bats

The ascorbic acid content of foliage available to wild primates and bats in Panama (in transition between wet and dry seasons) was lower than that of temperate zone foliage but higher than that of most fruits and vegetables. Intakes of ascorbic acid (mg/kg b.wt/day) by wild primates and frugivorous bats in Panama are much greater than that of most human populations.     

Ascorbic acid content of neotropical plant parts available to wild monkeys and bats

Summary The ascorbic acid content of foliage available to wild primates and bats in Panama (in transition between wet and dry seasons) was lower than that of temperate zone foliage but higher than that of most fruits and vegetables. Intakes of ascorbic acid (mg/kg b.wt/day) by wild primates and frugivorous bats in Panama are much greater than that of most human populations.     

Biosynthesis of ascorbic acid in chick embryos

Summary Biosynthesis of ascorbic acid was found in the kidneys (mesonephros and metanephros) of the chick embryo as well as in the yolk sac membrane. The activity of L-gulonolactone oxidase in the yolk sac membrane suggested that it was the major source of ascorbic acid in the chick embryo.I am grateful to Dr R. Jenness (Univ. of Minnesota) for the generous gift of L-gulonolactone and to Dr B. Sanders (Univ. of Texas) for the chick embryo samples     

Effects of L-lysine administration on certain aspects of ascorbic acid metabolism in weanling rats

Summary L-lysine administration to male weanling rats at a dose of 110.4 mg (25% LD₅₀) per 100 g body weight per day for 15 days reduced the liver total ascorbic acid level. The biosynthesis as well as the degradation of L-ascorbic acid was diminished under these conditions. The fall in liver total ascorbic acid level after L-lysine administration was ascribed to its reduced synthesis.Acknowledgment. The authors are thankful to the Council of Scientific and Industrial Research, India, for providing Junior Research Fellowships to Miss J. Basu and Miss K. Sen Gupta.     

Degradation of encephalitogenic protein in aerobic ascorbic acid solutions.

Aerobic ascorbic acid solutions are capable of extensively cleaving the peptide chain of the myelin basic protein. Cleavage occurred most readily with C-terminal to aspartic acid, serine, threonine, glutamic acid and leucine residues.     

Evolutionary implications of ascorbic acid production in the Australian lungfish

Summary It is shown that the Australian lungfish (Neoceratodus forsteri) synthesizes ascorbic acid in its kidney, suggesting that ascorbic acid synthesis started before the origin of the tetrapods.Acknowledgments. We would like to thank Dr G.C. Grigg, University of Sydney, Mr R. B. Humphries, Dr P.A. Janssens and Dr C.H. Tyndale-Biscoe, Australian National University, and Dr. M. Griffiths and J.C. MacIlroy C.S.I.R.O., Division of Wildlife Research for supplying the tissue.     

Effect of ascorbic acid on pigmentation of toad (Bufo melanostictus).

Administration of ascorbic acid in toad during breeding season results an increase in melanin pigments in skin, liver and vocal sac.     

Stimulative effect of 2,3-diphosphoglycerate on methemoglobin reduction by ascorbic acid

Summary The reduction of methemoglobin by ascorbic acid was accelerated by the presence of 2,3-diphosphoglycerate     

Ein Beitrag zum Wirkungsmechanismus des Chlortetrazyklins

Summary It has been stated that chlortetracyclin causes a depletion of ascorbic acid in rat adrenals.     

Noradrenergic control of ascorbic acid and glutathione concentrations in brown fat of cold-exposed rats

Ascorbic acid and glutathione concentrations increase in brown fat of cold-exposed rats. This phenomenon can be reproduced by noradrenaline or isoproterenol administration, and thus seems to be under sympathetic control. Histological study shows ascorbic acid storage in brown adipocyte nuclei.     

Utilization of ascorbic acid during post-embryonic development of chick skeletal muscle.

Ascorbic acid is utilized during the post-embryonic differentiation of skeletal muscle fibres in chick. While the fibres lose their heterogeneity with regard to ascorbic acid, they continue to exhibit differences in their metabolic rates in terms of the succinate dehydrogenase activity throughout life.     

Noradrenergic control of ascorbic acid and glutathione concentrations in brown fat of cold-exposed rats

Summary Ascorbic acid and glutathione concentrations increase in brown fat of cold-exposed rats. This phenomenon can be reproduced by noradrenaline or isoproterenol administration, and thus seems to be under sympathetic control. Histological study shows ascorbic acid storage in brown adipocyte nuclei.     

Degradation of encephalitogenic protein in aerobic ascorbic acid solutions

Summary Aerobic ascorbic acid solutions are capable of extensively cleaving the peptide chain of the myelin basic protein. Cleavage occurred most readily with C-terminal to aspartic acid, serine, threonine, glutamic acid and leucine residues.This research was supported in part by the National Multiple Sclerosis Society, grant number RG928-A-1.