TitleEvolution of the circadian clock in the genus of neurospora
NameWager, Craig (author), Lee, Kwangwon (chair), Shain, Daniel (internal member), Yakoby, Nir (internal member), Rutgers University, Camden Graduate School,
DescriptionCircadian rhythms are daily oscillations in biological activities that have a periodicity of approximately 24 hours. Underlying these rhythms are multiple molecular
oscillators that interact to form the circadian clock of an organism. The filamentous fungi and eukaryotic model organism, Neurospora crassa, possesses a core circadian oscillator known as the FREQUENCY (FRQ)/WHITE-COLLAR (WC) oscillator (FWO). Recent studies have shown that homologous Neurospora clock genes are not universally conserved across the fungal kingdom. Here, we aimed to identify similarities
and differences at the sequence, molecular, and macroscopic level of the circadian clock in divergently related species to N. crassa. The Neurospora discreta species complex contains numerous reproductive species with isolates that have been collected from all
around the world, and extend the latitudinal boundaries of Neurospora by inhabiting regions as far North as Alaska, thus this clade provides an unique opportunity to study the evolution of the fungal clock to diverse local environments. Sequence comparison of the Neurospora discreta PS4b (8579) core clock homologs revealed a high degree of overall conservation with notable exceptions in the presence of additional WC complex consensus binding sites in frequency, suggesting possible differences in gene expression.
Rhythms in asexual development in Neurospora discreta sensu stricto are overtly circadian regulated and underlying this were oscillations in FRQ abundance and phosphorylation were robust. Rhythmic conidiation in N. discreta PS4b 8579 was observed in cycling and free-running environments, however this expression was reliant upon several environmental conditions in order to be visualized. Molecular analysis of FRQ appears to reveal rhythms in abundance with decreased amplitude. An Alaskan strain, N. discreta PS4b 9981, demonstrated blue light mediated photo-responses, but was arrhythmic under free-running conditions and temperature cycling conditions. Phenotypes in asexual development of N. discreta species range from robustly clock controlled to arrhythmic. Western analysis of FRQ in N. discreta sensu stricto and N. discreta PS4b 8579, suggests that these phenotypes might reflect differences in the FWO.
Based on data from the current study, we propose that these changes in clock regulation might have played a role for the N. discreta species to adapt to their local environments.
NoteIncludes bibliographical references
Noteby Craig Wager
CollectionCamden Graduate School Electronic Theses and Dissertations
Organization NameRutgers, The State University of New Jersey
RightsThe author owns the copyright to this work.