Current Mailing Address:
Princeton University Department of Ecology & Evolutionary Biology Princeton, NJ 08544-1003 609-258-5146 gkdavis@princeton.edu http://www.princeton.edu/~gkdavis/
Abstract of Thesis
University of Chicago
August 2002
The Changing Role of Pax 3/7 Genes and The Evolution of Segmentation
Pax3/7 genes encode a class of transcription factors that play diverse developmental roles in most, if not all, metazoan taxa. In Drosophila, Pax3/7 genes include paired, gooseberry and gooseberry-neuro. During embryogenesis paired acts as one of several pair-rule genes to define the boundaries of future segments via the regulation of segment polarity genes, including gooseberry. The function of gooseberry-neuro is not yet defined, but the gene is expressed later in the developing nervous system. In light of the role these genes play in segmentation in the long germ insect Drosophila, this dissertation seeks to determine whether Pax3/7 genes might play similar foles in other arthropods, including short germ insects, crustaceans, myriapods and chelicerates, as well as annelids.
In order to investigate Pax3/7 expression in multiple species, crossreactive antibodies that recognize the products of Pax3/7 genes in a wide range of taxa were developed and their epitopes mapped and characterized. Using these crossreactive antibodies, the embryonic expression of presumptive Pax3/7 genes in the flour beetle Tribolium and the grasshopper Schistocerca are shown to mimic the pattern in Drosophila. In particular, stripes of a two-segment periodicity (pair-rule pattern) are shown to appear prior to the expression of the segment polarity gene engrailed. In non-insect arthropods, segmental stripes of Pax3/7 protein are shown to appear during segmentation in mysids, brine shrimp, a centipede and a spider, suggesting that a Pax3/7 role in segmentation was acquired deep within the arthropod lineage. Evidence of pair-rule patterning outside of insects, however, was not detected, suggesting that the early pair-rule expression pattern of these genes may have been acquired within the arthropod lineage and possibly within hexapods. With regard to Pax3/7 expression in annelids, no segmentally iterated expression of Pax3/7 genes prior to overt morphological segmentation was detected in the two polychaete species examined, suggesting that Pax3/7 genes do not play a role in segmentation in annelids, or at least in these particular polychaetes. Putative Pax3/7 expression is also briefly examined in larvae of the Red Abalone and possible discrepancies between the distribution of Pax3/7 protein and published descriptions of Pax3/7 mRNA in the case of zebrafish and ascidian embryos are also discussed.
Publications:
Davis, G. K., D’Alessio, J. A. and N. H. Patel (2005) Pax3/7 genes reveal conservation and divergence in the arthropod segmentation hierarchy, Developmental Biology 285: 169-184.
Davis, G. K. and N. H. Patel (2003) Playing by pair-rules? BioEssays 25: 425-9.
Davis, G.K. and N.H. Patel (2002). Short, long and beyond: molecular and embryological aproaches to insect segmentation. Annual Reviews of Entomology 47:669-699.
Davis, G.K., Jaramillo, C.A. and Patel, N.H. (2001). Pax group III genes and the evolution of pair rule pattern. Development, 128:3445-3458.
Browne, W., Davis, G. and J McClintock (2000) Ancestors and variants: tales from the cryptic, Evolution & Development 2(3): 130 (Review of meeting, The Developmental Basis of Evolutionary Change, University of Chicago, May 13-15, 1999).
Davis, G. K. and N. H. Patel (1999) The origin and evolution of segmentation, Trends in Genetics 24(12): M68-M72.
Presentations:
Davis, G. K. and N. H. Patel (2002) The changing role of pax3/7 genes during the evolution of protostomes (Talk given at the Evolution of Developmental Diversity, Cold Spring Harbor Laboratory, April 17 – 21)
Davis, G.K., Ludwig, M.Z. and N.H. Patel (2001) The Changing Role of paired in the Development of the Drosophila Male Reproductive System (Poster presented at The Developmental Basis of Evolutionary Change II, University of Chicago, October 25-28).
Davis, G.K., Jaramillo, C.A. and N.H. Patel (2001) Expression of Pairberry and the Evolution of Insect Pair-rule Patterning (Talk given at the Annual Meeting of the Society for Integrative and Comparative Biology, January 3-7).
Davis, G.K., Jaramillo, C.A. and N.H. Patel (2000) Expression of Pairberry and the Evolution of Segmentation (Talk given at Midwest Meeting of the Society for Developmental Biology).
Davis, G. K., Jaramillo, C.A. and N.H. Patel (2000). Expression of Pair-Berry and the Evolution of Segmentation (Poster presented at the Annual Meeting of the Society for Integrative and Comparative Biology, January 4-8).
Davis, G.K. and N.H. Patel (1999) Expression of Pairberry and the Evolution of Segmentation (Poster presented at the 58th Annual Meeting of the Society for Developmental Biology, June 13-18).
Davis, G.K. and N.H. Patel (1999) Expression of Pair-berry and the evolution of segmentation (Poster presented at The Developmental Basis of Evolutionary Change I, University of Chicago, May 13-15).
Education:
1996-2001
University of Chicago, Committee on Developmental Biology Advisor: Nipam H. Patel, Ph.D. Ph.D.1995
University of Pittsburgh, M.A. in History and Philosophy of Science.1992
Duke University, B.S. in Biology and Philosophy, Certificate in Women's Studies Magna Cum Laude, Phi Eta Sigma, Phi Beta Kappa
Research Experience:
Luce Scholar, Institute for Biomedical Sciences, Academia Sinica, Taipei, Taiwan
Worked on a neurophysiology project under C. Y. Chai.
(August 1992 - July 1993)Laboratory Technician, Duke University Medical Center, Durham, North Carolina
Worked in an electron microscopy laboratory investigating morphological
changes associated with learning and memory in the central nervous system of Octopus under J.D. Robertson.
(January - May 1991)Independent Study, Duke University Marine Laboratory, Beaufort, North Carolina
As a Howard Hughes undergraduate fellow, researched learning and memory in Octopus under J. D. Robertson.
(September - December 1990)Laboratory Technician, Duke University Primate Center, Durham, North Carolina
Involved in husbandry of captive lemurs.
Prepared and made casts of primate fossils under P. J. Chatrath.
(October 1988 - May 1989, September - December 1989)
