The Relationship Between Chlorophyll and the Carotenoids in the Algal Flagellate, Euglena

Abstract

Research for the "precursor" of chlorophyll in higher plants stimulated us to search for the "precursor" in Protista using similar techniques. Recently we have obtained an action spectrum for chlorophyll formation in Euglena (1). The action spectrum corresponds with the action spectrum for "greening" in etiolated Arena seedlings as determined by Frank (2) and with the absorption spectrum for protochlorophyll as given by Noack and Kiessling (3 a, b) and Koski and Smith (4). Studies by Smith (5) and Koski and Smith (4) indicate that protochlorophyll is the chlorophyll precursor as indicated in the action spectrum given by Frank (2).While the chlorophyll and carotenoid densities were being followed during this work, a decrease in carotenoid density was observed at high light intensities. Earlier, Strain (6) had suggested that the carotenoids are involved in chlorophyll formation based on the reports that the spectral bands which are most effective in chlorophyll formation are relatively ineffective in carotenoid formation (7) since a temporary depression of carotenoids but a steady increase of chlorophyll had been noted in the leaves of Phaseolus multiflorus on prolonged light exposure (7,8).Granick has reported a significant decrease in carotenoid density as Mg vinyl pheoporphyrin is transformed to chlorophyll in a mutant of Chlordla (9). A similar decrease in carotenoid density in oat seedlings has been observed at high light intensities and it has been suggested that the substance responsible for the carotenoid decrease is a prophyrin-type compound concerued with "esterifying" the porphyrin molecule and converting Mg vinyl pheoporphyrin to protochlorophyll, its phytol ester (10).In the present paper, an improved action spectrum is presented and, in addition, data on carotenoid formation and "destruction" are given. Also,

Events Surrounding the Early Development of Euglena Chloroplasts

“…Investigations of the light requirements for Chl synthesis in Euglena gracilis have indicated that PChl(ide) is the precursor pigment and photoreceptor (10,14,23,24). Both PChl and GM 1586-07.…”

A Molecular Morphology of Euglena gracilis var. bacillaris*

“…In all cases where structural changes occur in the chloroplast they are accompanied by spectral shifts in the absorption spectra of chlorophyll indicative of the appearance of pheophytin. The relationship of the eye-spot and flagella was considered as a structural unit and the energy for excitation was roughly estimated.H E PHYSICAL and chemical environment as it T affects the structure of the photoreceptors and the syntihesis of pigments-chlorophyll and carotinoidsin algal flagellates is under continuous investigation in our laboratory (23)(24)(25)(27)(28)(29). The uniqueness of Euglena as an experimental tool for studying plant + animal relations has already been pointed out ( 12,24).Euglena gracilis is a large unicellular algal flagellate and its gross structure is easily seen with an optical (light and phase) microscope, including the ridges of its cellular membrane, the flagella, the red "eye-spot", the large nucleus, and the green chloroplasts.…”

“…H E PHYSICAL and chemical environment as it T affects the structure of the photoreceptors and the syntihesis of pigments-chlorophyll and carotinoidsin algal flagellates is under continuous investigation in our laboratory (23)(24)(25)(27)(28)(29). The uniqueness of Euglena as an experimental tool for studying plant + animal relations has already been pointed out ( 12,24).…”

MacroMolecular Complexes

“…We have found the algal flagellate Euglena to be uniquely adaptable for experimental studies of the chloroplast structure, since Palade, 1953; Wolken and Sciwertz, 1953;Wolken et al, 1955; Wolken and Mellon, 1956;Wolken, 1956a). E. gracilis when light-grown contains manv green elongated cylindrical chloroplasts 5 to 10/>t in length and 0.5 to 2/>i in diameter.…”