Lilla Bartkó

Saint Louis, Missouri

M.S., University of Missouri-St. Louis, 2005

B.A. (Hon) Earth and Planetary Sciences - Macalester College

Thesis topic:

Molecular Evolution of the Homeobox gene Knotted-1(Kn1)
The Knotted1 gene and its homologues belong to the class of genes known as homeobox genes. Homeobox genes play a fundamental role in the development of the bauplan of plants and animals, coding for proteins that are transcription factors- gene products that regulate the expression of other genes. This regulation may be achieved through the specific interaction of highly conserved structural regions of the homeobox gene product and other molecules: the homeodomain binds to DNA, and the MEINOX domains are putative sites of interaction with other proteins. The expression of Knotted1 is associated with the undifferentiated status of tissues comprising the stem apical meristem (SAM). The determination of cell fate is the first step in the structural organization of the developing inflorescence. Differences in the timing and nature of tissue identity may influence the structural differences in inflorescences we observe within and among the clades comprising the grass family. Using sequence data from genomic DNA from a small sample of grasses representing the major subfamilies of Poaceae, I am examining the coding regions (exons) of Kn1 to see if changes at the level of codons indicate changes in function that may contribute to differences in gross morphology. To date, maximum likelihood analysis of aligned sequences of the taxa sampled indicate that the exons of Kn1 are highly conserved and under strong purifying selection.

I located conserved noncoding sequences (CNSs) upstream of the start codon and in the large intron. These regions may represent regulatory elements of Kn1. If differential expression of this gene is a component of the suite of processes resulting in differential morphology, then the regulatory regions of Kn1 may provide clues to such expression. Sequence analysis of regulatory elements will determine the nature of the selection pressure that such elements have experienced over their evolutionary history.

Publications:

These publications are from my previous research in geophysics. Geophysicists have had a detailed understanding of plate kinematics (the direction and relative rates of motion of tectonic plates) for some time, yet very little is known about plate dynamics, or the interacting forces that result in plate kinematics. These dynamics occur within the mantle, and it is thought that a coupling of forces between the earth's core and lower mantle is a key component in the mantle convection that is thought to drive plate motion. A means of observing the density/thermal structure of the mantle is seismic tomography. This remote sensing method utilizes wave data from seismic events to sample and image the structures of the earth's interior. Differences in the arrival time of characteristic body wave phases allow us to map regions of different physical properties such as density; this allows us to infer the location and shape of different thermal regimes, or features such as rising mantle plumes. My research focused on using methods of seismic tomography to map the core-mantle boundary, the ultimate site of the genesis of convection cells or mantle plumes.

Wysession, M.E., L. Bartkó, and J. Wilson, Mapping the lowermost mantle using core-reflected shear waves, J. Geophys. Res. 99(B7) 13,667-13,684, July 10, 1994.

Wysession, M.E., J. Wilson, L. Bartkó, and R. Sakata, Intraplate seismicity in the Atlantic Ocean Basin: a teleseismic catalog, Bull. Seismol. Soc. Am., 85, 775-774, 1995.

Wysession, M.E., R. W. Valenzuela, L. Bartkó, A.-N. Zhu, Investigating the base of the mantle using differential travel times, Phys. Earth Planet. Int., 92, 67-84, 1995.