In the dark, growth rates of Euglena gracilis were independent of culture pH between the limits of three to eight. Visible light of moderate intensity inhibited growth rates, with the degree of inhibition being markedly pH dependent. The most severe inhibition was observed at pH 4 to 5 , with little
Culture pH, CO2 tension, and cell division in Euglena gracilis Z
β Scribed by C. R. Jones; J. R. Cook
- Publisher
- John Wiley and Sons
- Year
- 1978
- Tongue
- English
- Weight
- 509 KB
- Volume
- 96
- Category
- Article
- ISSN
- 0021-9541
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β¦ Synopsis
Abstract
Growth characteristics of Euglena gracilis Z as functions of culture pH, CO~2~ tension, temperature, and lighting regime were investigated. The results are consistent with the possibility that cell division is preceded by a lowered intracellular pH. Also consistent with this possibility is the finding that division rhythmicity can be induced by periodic changes in CO~2~ tension. It is suggested that the rhythmicity is induced by changes in intracellular pH produced by carbonic acid.
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## Abstract Visible light of moderate intensity (1200 ftβcd) can severely inhibit cell division of a nonβphotosynthetic mutant of __Euglena gracilis__ when growth is supported by butanol, ethanol, or fumarate as sole carbon source. The degree of inhibition is pH dependent, being greatest at pH 4 to
Euglena gracilis Klebs (Z) was grown axenically and autotrophically in four-liter serum bottles at 25Β°C on an aerated, continuously stirred, inorganic salt medium. Four fluorescent illumination regimes were employed: ( 1 ) continuous bright light of 3500 lux (I&); ( 2 ) COntinuOuS dim light of 800 l