Elizabeth Marie Kramer



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There are constraints on the evolutionary process. A big question is how nature can generate alternate forms of a protein without interfering with its function. The beta tubulin protein of the fruit fly spermtail is an example of a protein that has not evolved for millions of years. The ultimate goal of this research is to determine how it evolves when it does. To do this, we need to first determine if beta tubulin tolerates change by testing the ability of a related but different beta tubulin to support the fruit fly sperm tail. In this case, the goal is to determine if Glossina morsitans (tsetse fly) beta 2, which is 14 amino acids different, can replace Drosophila beta 2 and generate motile sperm. Using genetic techniques we have expressed tsetse fly beta 2 in the fruit fly Drosophila melanogaster. We now need to selectively mate fruit flies to generate a fly that is a homozygote for both tsetse fly B2 and the null mutation for fruit fly B2. These flies will then be tested for fertility, TEM cross sections will be taken of the testis, and the testis morphology will be analyzed. If the resulting fruit flies are infertile with immotile sperm, then it is likely that the beta protein co-evolved with another component of the sperm tail. Having to wait for a second protein to evolve would slow the evolutionary process and explain why beta 2 has not evolved for 60 million years. But if the resulting fruit flies are fertile, then evolution took a very narrow path that maintained D. melanogaster beta 2 function in the face of 14 amino acid changes.

Publication Date


Project Designation

Independent Research

Primary Advisor

Mark G. Nielsen

Primary Advisor's Department



Stander Symposium project

The Effects of Tsetse Fly Beta 2 Tubulin on the Fruit Fly Axoneme