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G Constantopoulos

Publications and source records attributed to G Constantopoulos.

66 records · Page 4Linked to original sources
PubMed1970

Lipid metabolism of manganese-deficient algae. I. Effect of manganese deficiency on the greening and the lipid composition of Euglena gracilis Z.

The growth of photoautotrophic Euglena gracilis Z is strongly inhibited by manganese deficiency, whereas chlorophyll formation is not appreciably affected. The galactosyldiglyceride content of the manganese-deficient photo-autotrophic Euglena was about 40% lower on the basis of either chlorophyll content or dry weight. When dark-grown cultures of Euglena were grown photoheterotrophically in light sufficient for the greening of the cells, or photosynthesis, manganese deficiency resulted in a reduction of the cellular content of chlorophyll and galactosyldiglycerides to 40% of control values, indicating interference with chloroplast formation. The fatty acids of the photoheterotrophic manganese-deficient cells were mainly saturated, with an unusual accumulation (about 45%) of the total fatty acids) of myristic acid. In spite of this, the galactosyldiglycerides contain mainly unsaturated fatty acids. Ninety per cent of the fatty acids of the monogalactosyldiglyceride are unsaturated, including large amounts of alpha-linolenic acid. The ratio of chlorophyll to galactosyldiglyceride content of the cells was remarkably constant at all manganese deficiency levels.

Chlorophyll↗
PubMed1968

Release of free fatty acids and loss of hill activity by aging spinach chloroplasts.

The free fatty acid content of spinach chloroplasts, isolated at pH 5.8 to 8.0, has been found to vary between 3.1 and 5.5% of the total chloroplast fatty acids. When chloroplasts were incubated at room temperature for 2 hours, the free fatty acids increased by 42% and the Hill activity decreased by 70%. After 2 hours of incubation at 37 degrees , the free fatty acids increased about 3-fold and the Hill activity decreased to almost 0. The addition of crystalline bovine serum albumin largely prevented the loss of Hill activity at room temperature and at 5 degrees , but had little effect during incubation at 37 degrees . Both the release of free fatty acids and the loss of Hill activity were pH dependent. The losses were the least during incubation at pH 5.8 and the greatest during incubation at pH 8.0. The major free fatty acids released at pH 5.8 were saturated, while those released at pH 7.0 or 8.0 were mainly the unsaturated acids, alpha-linolenic acid and hexadecatrienoic acid.

Aging↗
PubMed1967

Isolation and characterization of glycolipids from some photosynthetic bacteria.

Glycosyl glycerides have been found in substantial amounts in Chloropseudomonas ethylicum but could not be detected in two strains of Rhodopseudomonas palustris. Rhodospirillum molischianum possibly contains small amounts of monoglycosyl diglyceride. The glycolipids of C. ethylicum have been separated into two components. One of these, glycolipid I, is a monogalactosyl diglyceride. Glycolipid II, upon acid hydrolysis, yields galactose, rhamnose, and a third, unidentified sugar. The glycolipids or total lipids of the photosynthetic bacteria examined contained saturated and monounsaturated, but none of the more highly unsaturated, fatty acids.

Bacteria↗
PubMedDate not supplied

Total and lipid-bound sialic acid in the cerebrospinal fluid of patients with brain tumors.

Total sialic acid (TSA) and lipid-bound sialic acid (LSA) were determined in the cerebrospinal fluid (CSF) from 63 patients with various neurological diseases. Of these, 27 had brain tumors: 20 had glioma, and 7 pituitary adenoma. TSA levels were significantly increased in the CSF of 18 of the 20 glioma patients (p less than 0.001), while in the adenoma patients were indistinguishable from the controls; with a 90 and 0% test sensitivity respectively. Conversely, the LSA concentrations were significantly elevated, both, in the glioma and pituitary adenoma patients (p less than 0.001), with a 68 and 100% test sensitivity respectively. These preliminary data suggest that measurement of TSA and LSA in the CSF should prove useful for the diagnosis of brain tumors and, perhaps, in the follow-up of patients undergoing treatment for brain tumors.

Adult↗