New rhythmic changes in mitosis and growth in low differentiated green and red marine macroalgae

• Published in: Russian journal of marine biology Vol. 33; no. 4; pp. 207 - 212
• Main Authors: Kalita, T. L., Titlyanova, T. V., Titlyanov, E. A.
• Format: Journal Article
• Language: English
• Published: 01.08.2007
• Subjects: Chlorophyta; Marine; Porphyra umbilicalis
• ISSN: 1063-0740; 1608-3377
• DOI: 10.1134/S1063074007040013

The cell division and vegetative growth of the thalli of simply differentiated macroalgae with a diffuse growth type-Ulva pseudocurvata (Chlorophyta) and Porphyra umbilicalis (Rhodophyta)-have been studied under natural and laboratory conditions. For this purpose the mitotic index and growth rate of algae were measured over 18 days. A diurnal rhythm of the mitotic index was revealed: the minimal mitotic index was registered in morning and daylight hours (for U. pseudocurvata 1-4%, for P. umbilicalis 0.5-2%), in the afternoon the index grew and reached its maximum 1 hour before dark (for U. pseudocurvata 12%, for P. umbilicalis 7%), then it slowly decreased during the night. In the studied algal species 2-3-and 6-day rhythms of mitotic index and growth rate were found for the first time both under natural and laboratory conditions. With constant white light these rhythms persisted for 9 days, this confirms the endogenous regulation of these rhythmic variations.