Lipid Alterations in Euglena gracilis Cells During Light-induced Greening<sup>*</sup>

Rosenberg, Abraham; Pecker, Marc

doi:10.1021/bi00890a019

Cited by 75 publications

(31 citation statements)

References 13 publications

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“…This result is in agreement with the observation made on the lipid composition of E. gracilis cells under different nutritional conditions. When Euglena cells were grown under photosynthetic conditions, they synthesized galactolipids in substantial quantity, whereas the cells grown under dark did not form any detectable amount of galactolipids (7). Table I also shows that the total lipid product is slightly more than the sum of mono-and digalactosyl diglyceride.…”

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confidence: 92%

Comparative studies of biosynthesis of galactolipids in Euglena gracilis strain Z.

Matson¹,

Fei²,

Chang³

1970

Plant Physiol.

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Biosynthesis of galactolipids in spinach chloroplasts has been reported (2,5). In these studies uridine diphosphate galactose was used as a galactosyl donor to some endogenous acceptor (diglyceride) (Branson Instruments Inc.). Chloroplasts were isolated from the broken cells by the procedure described by Carell and Kahn (Flb fraction) (1). The purity of the chloroplasts was checked under a microscope. Enzymatic synthesis of galactolipids was carried out by the method described previously (2). A typical reaction mixture contained, in 1 ml: uridine diphosphate galactose ("C) (0.03 lac giving 24,000 cpm with specific radioactivity of 25 Ac ,Mmole) in 0.1 ml; chloroplasts or broken cells (dark-grown cells) equivalent to about 5 mg of proteins in 0.5 ml; 0.4 ml of 0.1 M tris buffer, pH 7.4. At the end of a 1-hr reaction at 37 C, the reaction was stopped by adding 4 ml of chloroform-methanol (2:1 v/v) and heating at 55 C for 5 min. The lipid products were extracted once more with 2 ml of the chloroform-methanol solution. The lipid extract was washed four times with 2.5 ml of 0.9%c aqueous sodium chloride solution to remove residual radioactive uridine diphosphate galactose. A 1-ml aliquot of the lipid extract was transferred to a planchet, dried, and counted. The rest of the lipid extract was concentrated and separated on a column packed with silicic acid (Unisil, Clarkson Co., Williamsport, Penn.) into monogalactosyl diglyceride and digalactosyl diglyceride by eluting the column with 100 ml of a solution of 5% diethyl ether in methanol and equal volume of 20% diethyl ether in methanol, respectively. Each eluate was concentrated and counted on a planchet by means of a gas flow counter (Nuclear-Chicago).

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confidence: 92%

Comparative studies of biosynthesis of galactolipids in Euglena gracilis strain Z.

Matson¹,

Fei²,

Chang³

1970

Plant Physiol.

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“…1). Lipids accumulating in stationary phase Euglena have been shown to be wax esters (Rosenberg et al 1964). Lipid content did not increase in the control culture which was incubated with shaking indicating that wax esters do not accumulate in aerated cultures.…”

Section: Resultsmentioning

confidence: 99%

“…bacillaris, by transferring dark grown non-dividing cells, resting cells, into the light to induce chloroplast development. They found that the breakdown of the storage carbohydrate paramylum provided carbon and energy for the light induced synthesis of proteins, nucleic acids and lipids needed for chloroplast development (Schwartzbach et al 1975, Rosenberg et al 1964 found that lipids, mainly wax esters, accumulated in the cytoplasm of dark grown stationary Euglena and their breakdown was induced by light exposure providing an additional source of carbon and energy for light induced chloroplast development. …”

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Mechanism of Conversion from Heterotrophy to Autotrophy in Euglena gracilis

et al. 2007

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Summary Euglena grown to stationary phase in the dark without aeration accumulated lipids. When these high lipid cells are transferred to an inorganic medium and aerated, lipids were rapidly metabolized and the respiratory rate declined concomitant with the decline in cellular lipid content. Prolamellar bodies, propyrenoids and prothylakoids developed within the proplastid of dark aerated cells and the cells developed an increased capacity for chlorophyll synthesis manifested upon subsequent exposure to light. Lipid content did not decline in cells exposed to nitrogen and chlorophyll synthesis ability did not increase. The addition of an organic carbon source to cells at the start of aeration did not prevent lipid degradation. Organic carbon source addition and inhibitors of RNA and protein synthesis did however inhibit the development of an increased capacity for chlorophyll synthesis. These results suggest that oxygen triggers light independent proplastid development with the oxidative metabolism of lipids providing the carbon and energy for the synthesis of nucleic acids and proteins required for proplastid development in the dark. Growth of microorganisms requires carbon and energy for the synthesis of cellular components. Autotrophs utilize sunlight or the energy released by oxidization of inorganic compounds for growth while the breakdown of organic compounds provides the energy needed for the growth of heterotrophs. Most pathogenic bacteria, protozoa, and fungi are heterotrophs. The objective of this study was to analyze the mechanism of conversion from heterotrophy to autotrophy using the unicellular alga, Euglena gracilis. Key wordsEuglena gracilis grows heterotrophically on a variety of carbon sources in the dark showing a typical animal-type metabolism and when it is placed in the light on an inorganic medium it grows autotrophically exhibiting plant-type metabolism. Euglena is the only organism that can reversibly switch from animal-like heterotrophic metabolism to plant-like autotrophic metabolism making its taxonomic classification as a plant or animal problematic (Johnson 1968). Schiff's group (Osafune et al. 1990, Schiff andSchwartzbach 1982) has studied the transformation from a heterotroph to a phototroph, the greening of Euglena gracilis var. bacillaris, by transferring dark grown non-dividing cells, resting cells, into the light to induce chloroplast development. They found that the breakdown of the storage carbohydrate paramylum provided carbon and energy for the light induced synthesis of proteins, nucleic acids and lipids needed for chloroplast development (Schwartzbach et al. 1975, Rosenberg et al. 1964 found that lipids, mainly wax esters, accumulated in the cytoplasm of dark grown stationary Euglena and their breakdown was induced by light exposure providing an additional source of carbon and energy for light induced chloroplast development.

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“…Euglena grocilis grown in light had muich a-linolenate, while cells grown in the dark and its colorless multants had very small amouints of a-linolenate (10,11,18,27,28 …”

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confidence: 99%

“…Euglena grocilis grown in light had muich a-linolenate, while cells grown in the dark and its colorless multants had very small amouints of a-linolenate (10,11,18,27,28). The photosynthetic algae, Scenedesmus (11), and Chlorellaz vulgaris (3), Chlorella pyrenoidosa (24) also possessed large amotunts of a-linolenate.…”

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confidence: 99%