Graduation Year

2020

Document Type

Open Access Senior Thesis

Degree Name

Bachelor of Arts

Department

Biophysics

Reader 1

Janet Sheung

Reader 2

Emily Wiley

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© 2020 Eliana B Smithstein

Abstract

Stentor are large, unicellular ciliates of the Heterotricha order. They live in both freshwater and marine habitats and are mostly found in ponds. I studied Stentor polymorphus, which is a species of Stentor only recently discovered to be lab culturable. They range from 0.5-1.5mm in length and are unusual because they live with endosymbiotic algae and are much more likely than other, more widely studied, species of Stentor to form aggregates while they are eating. There are three main components to this thesis: First, I established protocols for keeping a viable S. polymorphus culture, since no protocols had been published on the care and upkeep of a culture of this species. Second, I established protocols for and collected preliminary data on a single S. polymorphus cell feeding. Third, I developed imaging and data analysis protocols to investigate the ciliary flows of S. polymorphus.

In the wild, Stentor do not differentiate between active or passive food sources. Thus, I tested the usefulness of Chlamydomonas reinhardtii and 2% buttermilk as particle tracers to study the ciliary flows of S. polymorphus. Even with a limited data set due to the COVID-19 pandemic, there was a significant difference between the relative vortex sizes. S. polymorphus was able to create a larger vortex relative to its cell size in a buttermilk solution than it could make in a Chlamydomonas reinhardtii solution. To further my research, videos of S. polymorphus eating in colonies could be compared to them eating individually to analyse whether the aggregates are evolutionarily advantageous in any way.

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