Molecular investigation of stalk formation and growth rates in Didymosphenia geminata

Larsen, Krista Maria

Molecular investigation of stalk formation and growth rates in Didymosphenia geminata

dc.contributor.advisor	Jackson, Leland J.
dc.contributor.author	Larsen, Krista Maria
dc.contributor.committeemember	Rogers, Sean M.
dc.contributor.committeemember	Vamosi, Jana C.
dc.date	2018-06
dc.date.accessioned	2018-04-04T21:41:56Z
dc.date.available	2018-04-04T21:41:56Z
dc.date.issued	2018-04-02
dc.description.abstract	Didymosphenia geminata, a freshwater diatom, can produce thick benthic mats of stalk material. The cause of excess stalk formation is proposed to be low soluble reactive phosphorus (SRP) concentrations or a mat-forming genetic variant. Molecular studies on D. geminata are few, partly due to the lack of a reliable DNA extraction technique for the diatom, but have the ability to elucidate the drivers of mat formation. Specifically, comparison of gene expression between mat and non-mat-forming sites using reference genomes, may reveal underlying mechanisms behind growth and stalk formation. The objectives of this study were to: 1) identify gene products, expressed only at a mat or non-mat-forming site in Alberta (AB), involved in cell division or stalk formation from the reference genomes of P. tricornutum, T. pseudonana and C. crescentus; 2) compare SRP and growth rate, using frequency of dividing cells (FDC), between a mat-forming and non-mat-forming site; 3) compare FDC between multiple mat-forming sites in AB and British Columbia (BC); and 4) compare the quantity and quality of DNA obtained from mat-forming D. geminata using various preservation buffers, storage temperatures and extraction methods, including organic extraction, the Qiagen DNeasy® Plant Mini Kit, and a version of the kit procedure modified for D. geminata. Sixty-six putative gene products from the reference genomes were expressed only in the mat-forming sample, while 172 were expressed only in the non-mat-forming sample. FDC and SRP were higher at the non-mat-forming site, with no significant difference between FDC in AB and BC. Collectively, these results support previous findings that D. geminata forms excess stalk material under low SRP and increases cell division under higher SRP. However, an anomalous observation of mat formation at a site with 0.00986 mg/L SRP indicates stalk formation may be influenced by additional factors. In addition, the results of this study indicate that DNA extracted from samples stored in 95% EtOH at -80°C, using the modified kit method, had the best combination of quantity and quality.	en_US
dc.identifier.citation	Larsen, K. M. (2018). Molecular investigation of stalk formation and growth rates in Didymosphenia geminata (Master's thesis, University of Calgary, Calgary, Canada). Retrieved from https://prism.ucalgary.ca. doi:10.11575/PRISM/31764	en_US
dc.identifier.doi	http://dx.doi.org/10.11575/PRISM/31764
dc.identifier.uri	http://hdl.handle.net/1880/106473
dc.language.iso	eng
dc.publisher.faculty	Graduate Studies
dc.publisher.faculty	Science
dc.publisher.institution	University of Calgary	en
dc.publisher.place	Calgary	en
dc.rights	University of Calgary graduate students retain copyright ownership and moral rights for their thesis. You may use this material in any way that is permitted by the Copyright Act or through licensing that has been assigned to the document. For uses that are not allowable under copyright legislation or licensing, you are required to seek permission.
dc.subject.classification	Ecology	en_US
dc.subject.classification	Genetics	en_US
dc.title	Molecular investigation of stalk formation and growth rates in Didymosphenia geminata
dc.type	master thesis
thesis.degree.discipline	Biological Sciences
thesis.degree.grantor	University of Calgary
thesis.degree.name	Master of Science (MSc)
ucalgary.item.requestcopy	true
ucalgary.thesis.checklist	I confirm that I have submitted all of the required forms to Faculty of Graduate Studies.	en_US