Evidence for continuous potential for gene transcription during the cell cycle of a eukaryote

Synchronous cultures of Chlorella pyrenoidosa (strain 7- 11-05) have been utilized to measure the potential expression of the structural gene for isocitrate lyase (three D_S-Isocitrate glyoxylate-lyase, EC 4.1.3.1) during the cell cycle. Synthesis of the enzyme could be induced by placing cultures in the dark on acetate, with the induction process occurring in a quadratic fashion. By addition of cycloheximide during the course of induction, the increase in isocitrate lyase activity was shown to result from de novo protein synthesis. In the absence of protein synthesis the enzyme was stable for at least five hours. The pattern of uninduced isocitrate lyase synthesis during the cell cycle in continuous light, paralleled the stepwise increase of total cellular DNA. The enzyme appeared to be fully repressed for most of the cell cycle, and was derepressed during the time of DNA replication. Isocitrate lyase could be induced at all times in the cell cycle, indicating that the potential for gene expression is continuous in this eukaryote. A time lag was observed between the beginning of DNA replication and the initial rise in potential for isocitrate lyase gene expression. The control of gene expression in Chlorella appeared to be similar to that found in a fission yeast.

Name thesis:degree_name

Ph. D.

Level thesis:degree_level

doctoral

Discipline thesis:degree_discipline

Biochemistry and Nutrition

Department dc:contributor.department

Biochemistry and Nutrition

Grantor dc:publisher

Virginia Polytechnic Institute

Year dc:date.issued

1970

Author dc:creator

• Baechtel, F. Samuel

Statement dc:rights

• In Copyright

Licence dc:rights.uri

• http://rightsstatements.org/vocab/InC/1.0/

Language dc:language.iso

en_US

Handle dc:identifier.uri

http://hdl.handle.net/10919/94523

OAI identifier oai:identifier

oai:vtechworks.lib.vt.edu:10919/94523