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Adaptations in Growth and Division in Euglena Effected by Energy Supply *
Author(s) -
COOK J. R.
Publication year - 1963
Publication title -
the journal of protozoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.067
H-Index - 77
eISSN - 1550-7408
pISSN - 0022-3921
DOI - 10.1111/j.1550-7408.1963.tb01703.x
Subject(s) - euglena gracilis , photosynthesis , euglena , light intensity , cell division , limiting , botany , biology , division (mathematics) , respiration , pigment , biophysics , strain (injury) , biochemistry , chemistry , cell , chloroplast , optics , physics , mechanical engineering , arithmetic , mathematics , organic chemistry , anatomy , gene , engineering
SYNOPSIS.Euglena gracilis (strain Z) was grown auto‐trophically at different light intensities, saturating or limiting for cell division. Adaptation to culture at each light intensity was gauged from division rate, mass, protein, photosynthetic pigments, nucleic acids, volume, paramylum, lipids, respiration, and photosynthesis. Illumination above 1200 foot‐, candles was saturating for all aspects of cell growth; the highest intensity examined (3,000 ft‐c) slightly inhibited cell division. Intensities between 400 and 1200 ft‐c were saturating for all except photosynthesis and paramylum accumulation. Intensities less than about 200 ft‐c became limiting for all fractions except protein, which remained constant over the range 120–3000 ft‐c, dropping, however, at 65 ft‐c. Concentration of photosynthetic pigments increased as light intensity decreased. Absolute synthetic rates were estimated for the individual Euglena cell for the measured cell constituents. While most followed a predictable pattern, increasing with light intensity to saturating levels, the synthetic rates for the pigments went through maxima at 190 ft‐c. Since fixed carbon in limiting light is so apportioned that protein is synthesized to the exclusion of paramylum, one concludes that the energy requirements for cell growth (measured as protein synthesis), and to a lesser extent cell division, have a higher priority than do those activities concerned more directly with maintenance.