Ultradian and circadian rhythms of phototaxis in chlamydomonas reinhardii
Year: 2025
Type: article
Abstract: Circadian changes in the rate of phototaxis were monitored for up to 12 days in cultures of the single-celled photosynthetic alga, Chlamydomonas reinhardii. After growth under either photo-organotrophic or photoautotrophic conditions (LD: 12, 12) organisms incubated in continuous dim light showed circadian rhythms of cell numbers and phototaxis, with the maximum rate of phototaxis occurring during subjective day. The phototaxis rhythm could also be initiated by a decrease in light intensity, and showed temperature compensation for organisms in photoorganotrophic and phototoautotrophic growth media respectively over a temperature range 17°- 28° C. Ultradian rhythms with periods of about 1 h are more easily detectable during growth with acetate, i.e., as is the case with fast-growing non-photosynthetic unicellular protozoa (e.g., Acanthamoeba, Tetrahymena, Crithidia), and yeasts cultured using rich media (cell division times 5.0 - 0.3 h). It is well established that colourless algae have most likely to have evolved by loss of chloroplasts from their photosynthetic ancestors (e.g., Polytomella coeca from C. reinhardii , and Prototheca zopfii from Euglena gracilis) : all four species are rapidly dividing and exhibit essential central metabolic mechanisms of cellular energetics and coherence during their growth and survival. Whereas these green algae have been shown to have many industrial uses, their colourless heterotrophic counterparts have not yet been exploited.
Language: English
Subfield: Endocrine and Autonomic Systems
Field: Neuroscience
Domain: Life Sciences
Open Access status: gold
Estimated APC paid: $2,700
OpenAlex ID: W4416910434