Labib Rouhana, Ph.D. (Advisor); Scott Baird, Ph.D. (Committee Member); Shulin Ju, Ph.D. (Committee Member)
Master of Science (MS)
Microtubule-based structures are an essential part of eukaryotic cells as they are involved in a number of processes such as phagocytosis, chromosome separation, intracellular transport, and cell motility. Transport along microtubules is accomplished by kinesin superfamily proteins (KIFs), which are motor proteins that bind cargo and use ATPase activity to move along microtubules in an anterograde fashion. One of the most common kinesin complexes is the heterotrimeric Kinesin 2 complex which is composed of KIF3 subunit dimers and the Kinesin Associated Protein 3 (KAP3). This complex is known as the KIF3 complex and functions along microtubules in cilia and flagella. A KAP3 ortholog in Schmidtea mediterranea (Smed-KAP3) was identified as a candidate gene with enriched expression in the planarian reproductive system. Whole-mount in situ hybridization analyses confirmed preferential expression of Smed-KAP3 in planarian testes. Functional analysis by RNA interference (RNAi) followed by immunofluorescence revealed loss of flagella in elongating spermatids of Smed-KAP3 knockdown animals. Additionally, Smed-KAP3(RNAi) planarians exhibited an inchworm-like movement rather than the continuous gliding seen in negative control knockdowns. The inchworm-like phenotype is indicative of dysfunctional epidermal motile cilia, which line the outside of the organism and propel planarian movement. This was confirmed by transmission electron microscopy analysis, which showed fewer and shorter epidermal cilia on Smed-KAP3(RNAi) animals. From these data we conclude that Smed-KAP3 is required for assembly and/or maintenance of planarian motile cilia and flagella. Broader implications of this research include information that can be applied towards understanding asthenozoospermia and ciliopathies caused by motile cilia disfunction.
Year Degree Awarded
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