?-1,3 Glucan: A Source of Carbon and Energy for Chloroplast Development in Euglena A Gracilis

Abstract

The illumination of dark-adapted cells of E. gracilis under non-dividing conditions induced not only the production of chloroplasts but also a rapid breakdown of J3-1,3�glucan, the reserve carbohydrate of this organism. The decrease in ,8-1,3-glucan preceded the synthesis of most of the chlorophyll and was confined to the first 24 hr of illumination, whereas chlorophyll synthesis continued for at least 72 hr.

Events Surrounding the Early Development of Euglena Chloroplasts

“…3), the lightinduced rate of degradation is lower in SM-treated cells than in untreated cells. Normally, the developing plastid utilizes both the carbon and energy produced by paramylum degradation for the synthesis of plastid constituents (10 (9) in agreement with the idea that paramylum degradation is inhibited by products produced by its degradation.…”

“…The amount of Chl synthesized is related to the amount of paramylum degraded during development (14), and tracer studies have shown that the carbon derived from paramylum degradation is incorporated into chloroplast lipids (10).…”

“…The control of these compartments seems to involve separate photoreceptors, the plastid compartment being regulated by a red-blue photoreceptor similar or identical to PChl(ide) (13) whereas the nonchloroplast compartment(s) are regulated by a photoreceptor absorbing mainly in the blue region of the spectrum (12,27). Among the processes which have been shown to be under light control and required in the nonchloroplast portion of the cell is the aerobic metabolism of paramylum which is necessary to supply energy and carbon for plastid development (9,10,14,19,25). In this paper we show that light can be replaced by CEX', a specific inhibitor of cytoplasmic protein synthesis (1,18), or by LEV, a structural analog of ALA (2,23), the precursor of tetrapyrroles such as Chl.…”

Comparative Profiling Analysis of Central Metabolites inEuglena gracilisunder Various Cultivation Conditions

“…8) The results suggested that the direction of carbon flow in these cells was changed by the activation of glycolytic pathways for the upregulation of protein and lipid biosynthesis. 9,10) In order to determine the effects of light on the regulation of central metabolism, the metabolite compositions of dark-and light-grown cells were compared using a metabolic profiling analysis technique. From 20 mg of freeze-dried E. gracilis cells, metabolites were extracted by the chloroform-methanol-water method, 11) and were subjected to gas chromatography mass spectrometry (GC-MS; Pegasus HT, LECO) 12) and liquid chromatography-tandem mass spectrometry (LC-QqQ-MS; Agilent 6460).…”

Relation between Paramylum Content and the Length of the Lag Period of Chlorophyll Synthesis during Greening of Dark-grown Euglena gracilis

“…It accumulates when Euglena is grown on an organotrophic medium in the dark and is consumed either in the dark when cells receive, at the end of the exponential phase of growth, nitrogen and/or phosphorus (10), or when cells are transferred to the light (7,8,10,23). In the latter case, it provides carbon materials and energy requirements during the early times of plastid formation before photosynthetic activity is able to satisfy cell demands (8,22,23).…”