Spencer Hills

Date of Award

2018

Document Type

Thesis

Degree Name

Bachelors

Department

Natural Sciences

First Advisor

Clore, Amy

Area of Concentration

Natural Sciences

Abstract

Cells of some species of slime mold, as well as the model amoeba Entamoeba invadens, are attracted to the furrowing region of dividing cells in telophase, physically assisting neighboring cells with cytokinesis in a process known as cytokinetic midwifery. However, little is known with respect to possible inter-species interactions or chemotactic behavior related to the cytokinetic midwifery phenomenon. In an attempt to stimulate cytokinetic midwifery, brefeldin A (BFA), a secretory pathway inhibitor and known inhibitor of cytokinesis in Caenorhabditis elegans, was applied to experimental agar plates upon which the slime mold Dictyostelium discoideum was cultured, and cells were monitored for evidence of cytokinesis inhibition and possible midwifery. In addition, to enhance our knowledge of the inter-species facet of this phenomenon and to see if one species can assist another, D. discoideum cells were incubated alongside the acellular slime mold Physarum polycephalum on agarose plates treated with brefeldin A. To provide controls, co-cultured well as lone D. discoideum were grown in the absence of BFA. Under BFA treatment conditions, a significant portion of D. discoideum cells were found to contain two prominent, approximately nuclear-sized bodies. While this observation may indicate that the cells were bi-nucleate, it could also be indicative of a feature known as a contractile vacuole. BFA is known to inhibit emptying of contractile vacuoles, and this could have occurred in the BFA-treated samples of the present study. Furthermore, there were no significant differences between D. discoideum cells that had been co-cultured with P. polycephalum and those cultured alone. This study should be repeated using a verified cytokinesis inhibitor for D. discoideum and a cellular slime mold that is a close relative to D. discoideum, in order to elucidate the true worth of the co-culturing method. Collectively, these findings, along with literature review, demonstrate that cytokinetic midwifery is a more complex phenomenon than originally anticipated, and that its mechanism and occurrence during inter-species interactions warrant further investigation.

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