Graduation Year

2015

Date of Submission

4-2015

Document Type

Campus Only Senior Thesis

Degree Name

Bachelor of Arts

Department

Molecular Biology

Reader 1

Patrick M. Ferree

Reader 2

Gretchen Edwalds-Gilbert

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Terms of Use for work posted in Scholarship@Claremont.

Rights Information

© 2015 Kelsey E. Kaeding

Abstract

Genomes usually work together to promote the fitness of the organism, but sometimes parts of the genome cause intragenomic conflict, and act selfishly in order to promote their transmission. An example of this conflict is a selfish B chromosome known as paternal sex ratio (PSR) in the jewel wasp Nasonia vitripennis. Transmitted solely to new progeny with the sperms hereditary material, PSR completely destroys the paternal genome during the first mitotic division of the newly fertilized embryo. This effect enhances transmission of the PSR chromosome because of the unique haplodiploid reproductive mode of Nasonia and other members of the hymenopteran insect group. Through transcriptomic analyses, our group recently discovered that the PSR chromosome expresses eleven transcripts in the wasp testis. A plausible hypothesis is that one or more of these transcripts play some role in paternal genome elimination. In this study I have begun to test this hypothesis by screening through a set of previously produced truncated versions of the PSR chromosome. Specifically, I used PCR in order to screen these truncated chromosomes for the presence of each of these PSR-specific transcripts. I could then correlate the level of genome elimination induced by each truncated PSR chromosome with the presence or absence of the expressed transcripts. My work has established that (i) three of the eleven transcripts are likely not involved in genome elimination; (ii) no single transcript alone causes genome elimination; (iii) the remaining eight of eleven transcripts are viable candidates for causing genome elimination; and (iv) it is likely that a sub-group of these transcripts may operate together to induce this effect. I discuss several models in which PSR-expressed RNA molecules could operate to cause genome elimination.

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