Analysis of Circadian Rhythms of Phototaxis and Growth Patterns in a Green Alga Using Separate Media and Temperatures
Grade Level at Time of Presentation
Secondary School
Institution
Western Kentucky University
KY House District #
20
KY Senate District #
32
Faculty Advisor/ Mentor
Sigrid Jacobshagen, Ph.D.
Department
Dept. of Biology
Abstract
Chlamydomonas reinhardtii is a unicellular green alga utilized as a model organism for circadian rhythm research with its similar circadian clock to humans of 24-25 hours. The strain cmj030 of C. reinhardtii is the basis for a large mutant library to test for genes involved in a number of cellular processes. Yet when testing the phototaxis, the ability to respond to light, of cmj030, no circadian rhythm was detectable, preventing its mutant analysis. In order to rectify this, we analyzed how separate growth media would affect and possibly encourage a circadian rhythm of phototaxis. Strain cmj030, the control strains CC124 and CC1690 with detectable rhythms, and a different algal species, C. moewusii, were grown in the previously utilized 0.3 High Salt Medium (HSM) and the new Tris Phosphate (TP) medium. The cultures were analyzed for growth patterns via weekly cell counts and for circadian rhythms via the usage of the phototaxis machine. In growth analysis, cmj030 showed more rapid growth in TP medium. Also, the larger cells of CC1690 and C. moewusii displayed less clumping in TP, allowing for more accurate counts. Phototaxis data showed similar levels of circadian rhythms across media, with CC124 and CC1690 displaying rhythms in both media and cmj030 in none. We are currently testing different temperatures during phototaxis and their effects on the circadian rhythm. The same strains of C. reinhardtii are grown in both TP and 0.3 HSM media and tested for phototaxis at the standard 20˚C as well as 10 ˚C and 30 ˚C to observe how the change affects the circadian rhythm and its period. Results will be useful in learning how to best cultivate these strains within a lab setting, but also how these green algae behave in environments with rising temperatures.
Analysis of Circadian Rhythms of Phototaxis and Growth Patterns in a Green Alga Using Separate Media and Temperatures
Chlamydomonas reinhardtii is a unicellular green alga utilized as a model organism for circadian rhythm research with its similar circadian clock to humans of 24-25 hours. The strain cmj030 of C. reinhardtii is the basis for a large mutant library to test for genes involved in a number of cellular processes. Yet when testing the phototaxis, the ability to respond to light, of cmj030, no circadian rhythm was detectable, preventing its mutant analysis. In order to rectify this, we analyzed how separate growth media would affect and possibly encourage a circadian rhythm of phototaxis. Strain cmj030, the control strains CC124 and CC1690 with detectable rhythms, and a different algal species, C. moewusii, were grown in the previously utilized 0.3 High Salt Medium (HSM) and the new Tris Phosphate (TP) medium. The cultures were analyzed for growth patterns via weekly cell counts and for circadian rhythms via the usage of the phototaxis machine. In growth analysis, cmj030 showed more rapid growth in TP medium. Also, the larger cells of CC1690 and C. moewusii displayed less clumping in TP, allowing for more accurate counts. Phototaxis data showed similar levels of circadian rhythms across media, with CC124 and CC1690 displaying rhythms in both media and cmj030 in none. We are currently testing different temperatures during phototaxis and their effects on the circadian rhythm. The same strains of C. reinhardtii are grown in both TP and 0.3 HSM media and tested for phototaxis at the standard 20˚C as well as 10 ˚C and 30 ˚C to observe how the change affects the circadian rhythm and its period. Results will be useful in learning how to best cultivate these strains within a lab setting, but also how these green algae behave in environments with rising temperatures.