Date of Award
1999
Degree Type
Thesis
Degree Name
Master of Science in Botany
Department
Biological Sciences
First Advisor
Alison Roberts
Abstract
Exposure of batch cultures of Tetraselmis chuii to three levels (0.020, 0.126 and 0.217 m W/cm2) of artificial UV-B caused a depression of exponential growth corresponding to UV-B dose. Three UV-B experiments were conducted. Cultures were maintained at 25 °C on a 18L:6D photoperiod for the first two experiments and at 12L: 12D for the last experiment. Growth was measured daily by measuring optical density at a standard wavelength of 750 nm. This was compared periodically with hemacytometer cell counts. Cell morphology (projected cell area, length, width, perimeter, and roundness) was determined by microscopic image analysis, and showed some significant differences among the three UV treatments, and their growth phases. In vivo spectrophotometric characterization of the cell cultures indicates a spectral response to UV-B dose, although without any well-defined peaks. There was no evidence of change in cellular chlorophyll levels as determined from in vivo optical density at 675 nm. Cell cultures in all treatments became biphasic, with a suspended and a sedimented population. Mean growth rates ranged from nearly one (0.84) doubling per day in the lowest UV-B treatment (control) to no doubling day -1 in the highest UV-B level. The difference in growth responses between the two exposure photoperiods indicates a possible damage/repair threshold level. Additional observations were made on cell motility and media spectral characteristics.
Recommended Citation
Audette, Charles T., "STUDY OF THE EFFECTS OF ULTRAVIOLET RADIATION ON TETRASELMIS CHUII GROWTH AND MORPHOLOGY" (1999). Open Access Master's Theses. Paper 2676.
https://digitalcommons.uri.edu/theses/2676