Date of Award




Document Type

Master's Thesis

Degree Name

Master of Science (MS)


Department of Biomedical Sciences

Content Description

1 online resource (xii, 134 pages) : color illustrations.

Dissertation/Thesis Chair

Terence Wagenknecht

Committee Members

Janice Pata


Foraminifera, Microtubules, Allogromiidae, Cytoplasmic filaments

Subject Categories

Biology | Genetics


Foraminifera have unusually fast dynamic movements resulting in the reorganization of the microtubule cytoskeleton (Travis and Bowser, 1988; Travis et al., 1983). We are interested in using Reticulomyxa filosa as a model to investigate the mechanisms and factors that regulate such fast microtubule assembly/disassembly rates (Chen and Schliwa 1990; Travis and Bowser, 1991; Welnhofer and Travis, 1996). Compared to conventional microtubule assembly and disassembly models, foraminifera tubulin can exist in another assembly state termed helical filaments. A novel form of tubulin, β2, in foraminifera is likely critical to these unusual microtubule properties. This thesis investigates Reticulomyxa filosa, a freshwater foraminifera and the analysis of a highly nonconserved isoform of β-tubulin, β2, which is co-expressed with the canonical type β-tubulin. A alignment of β2 tubulin sequences determined a consensus sequence that demonstrated several nonconserved substitutions may weaken adjacent lateral interprotofilament dynamics. These amino acid substitutions may create stronger lateral bonds between the two adjacent neighboring β-tubulin monomers. Fluorescence in situ hybridization experiments confirm that both β-tubulin isotype genes exist in R.filosa nuclei. We confirmed that R.filosa reticulopodia-containing microtubules treated with divalent cations can induce helical filaments as shown previously in a different foram, Allogromia laticollaris. The model of microtubules to helical filament transition requires accurate measurements of individual helical filaments. Treatment conditions required to obtain helical filaments that are suitable for high resolution cryo-EM future studies have been determined and the initial data set of helical filament dimensions is measured. Together this data agrees with similar studies in Allogromia laticollaris and provides a platform to further resolve the microtubule to helical filament transition model.