The Negro in Colonial South Carolina

Kennedy, Melissa; Klingberg, Frank J.

doi:10.2307/271531

Cited by 10 publications

(14 citation statements)

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“…The majority of the radioactivity not bound by the resin was identified as choline by ascending paper chromatography (18) and was reduced in the mutant regardless of temperature. Both phosphorylcholine and CDP-choline were retained by the resin and eluted with formic acid (17 Cells were grown for several generations at 33°C in medium supplemented with 32P3 (2 ,uCi/ml) to label the phospholipids to constant specific activity. The cells were then replated at 3 X 105 cells per 100-mm dish at 33°C in medium containing 32P at the same specific activity.…”

Section: Resultsmentioning

confidence: 99%

Autoradiographic detection of animal cell membrane mutants altered in phosphatidylcholine synthesis.

Esko¹,

Raetz²

1980

Proc. Natl. Acad. Sci. U.S.A.

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We have screened approximately 20,000 colonies of Chinese hamster ovary cells immobilized on filter paper [Esko, J. D. & Raetz, C. R. H. (1978) Proc NatL Acad. Sci. USA 75, 1190USA 75, -1193 for strains unable to incorporate [methl-"'CJcholine into trichloroacetic acid-precipitable phospholipid at 40'C. Mutant 58, identified in this way, was specifically defective in choline incorporation, and other isolates were also blocked in thymidine and leucine incorporation into DNA and protein, respectively. Further analysis of mutant 58 revealed that the strain grew almost normally at 330C, the permissive temperature, but divided only once at 40'C, the restrictive temperature. After a 20-hr incubation at 400C, the phosphatidylcholine level dropped from 41% to 20% in the mutant whereas other phospholipids, including sphingomyelin, continued to accumulate. Wild-type cells contained approximately 50% phosphatidyicholine at both temperatures. Anion-exchange chromatography of the water-soluble choline metabolites extracted from mutant 58 revealed that phosphorylcholine accumulation increased from 6 nmol/mg of protein at 330C to 42 nmol/mg of protein at 40'C whereas CDP-choline decreased from 0.42 nmol to less than 0.07 nmol per mg of protein. Phosphorylcholine also increased in wild-type cells shifed from 330C to 40°C (from 1.8 nmol to 16 nmol per mg of protein), but the level of CDP-choline was not altered (from 0.52 nmol to 0.58 nmol per mg of protein). Enzymatic assays of extracts prepared from mutant and wild-type cells revealed a reduction of CTP: phosphorylcholine cytidylyltransferase (EC 2.7.7.15) activity (CDP-choline synthetase) in the mutant to 1/40th that in the wild type, and mixing experiments excluded the production of antagonists to CDP-choline synthesis in the mutant. Thus, the inability of the mutant to generate normal amounts of phosphatidylcholine in vivo was correlated with an enzymatic lesion in the biosynthesis of CDP-choline in vitro.Phosphatidylcholine is a major structural component of most cells possessing internal membranes (1, 2), representing about half of the membrane phospholipid. Its synthesis appears to be localized on the cytoplasmic face of the endoplasmic reticulum (3, 4), but little is known about the biochemical and genetic factors that control the relative amount and distribution of this lipid. Most subcellular membranes contain different amounts of phosphatidylcholine (1) The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordance with 18 U. S. C. §1734 solely to indicate this fact.

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Section: Resultsmentioning

confidence: 99%

Autoradiographic detection of animal cell membrane mutants altered in phosphatidylcholine synthesis.

Esko¹,

Raetz²

1980

Proc. Natl. Acad. Sci. U.S.A.

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“…During early work it was observed that the enzyme synthesizing phosphatidylcholine was more stable to lyophilization than that synthesizing phosphatidylethanolamine leading to the suggestion that two separate enzymes were involved [3]. This is supported by the susceptibility of cholinephosphotransferase to acylCoA inhibition compared with ethanolamine phosphotransferase [4] and the markedly different ratios between the two enzyme activities in various rat tissues [5,6].…”

Section: Introductionmentioning

confidence: 76%

Lack of competition between phosphatidylcholine and phosphatidyletranolamine synthesis in the membranes of Entodinium caudatum

Dawson

Letcher

1977

FEBS Letters

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“…There are two pathways for the de novo biosynthesis of phosphatidylcholine in the liver; one involving direct phosphorylation of choline and subsequent incorporation into phosphatidylcholine via a CDP-choline intermediate (22), and a second route involving methylation of phsophatidylethanolamine (23). In addition, it is known that methyla tion of phosphatidylethanolamine is a major pathway in the biosynthesis of phosphatidyl choline in female rats (24).…”

Section: Resultsmentioning

confidence: 99%

Sex Difference in the Development of Fatty Liver by Orotic Acid

Negishi¹,

Aizawa²

1975

Japanese Journal of Pharmacology

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-Effects of orotic acid on liver lipid accumulation and incorporation of methionine [methyl-"C] into liver phosphatidylcholine and protein, and into serum beta-lipoprotein were studied. Male and female rats of Wistar strain were fed a semisynthetic diet supplemented with 1 per cent orotic acid for 7 days. Feeding of orotic acid induced a marked fatty liver in female rats, but not in males. In female rats, radioactivity in liver phosphatidylcholine was significantly decreased by orotic acid, and that in liver protein was slightly decreased. In male rats, incorporation of methionine [methyl-'4C] into liver phosphatidylcholine and protein was unchanged between the control and the rats fed orotic acid. Radioactivity in serum beta-lipo protein was decreased to a greater extent in female rats than in males. These results suggest that sex difference in the development of fatty liver may be due to the difference in the effect of orotic acid on liver phosphatidylcholine biosynthesis.

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The Negro in Colonial South Carolina

Cited by 10 publications

References 0 publications

Autoradiographic detection of animal cell membrane mutants altered in phosphatidylcholine synthesis.

Autoradiographic detection of animal cell membrane mutants altered in phosphatidylcholine synthesis.

Lack of competition between phosphatidylcholine and phosphatidyletranolamine synthesis in the membranes of Entodinium caudatum

Sex Difference in the Development of Fatty Liver by Orotic Acid

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