Christine A. Byrum
Associate Professor
Education
Postdoc - Duke University, Durham, NC
Postdoc - University of Hawaii at Manoa, Honolulu, HI
Ph.D. - University of Texas, Austin, TX
M.S. - Clemson University, Clemson, SC
B.S. - College of William and Mary, Williamsburg, VA
Research Interests
The Byrum lab uses a combination of genomic, molecular, and experimental approaches to study early development in marine invertebrates. This lab is particularly interested in how modifications in cell signaling pathways have affected the evolution of animal body plans. Using functional genomic approaches to determine which signals activate and repress specific genes, the lab investigates the molecular basis of early developmental events affecting formation of endoderm, mesoderm, and their derivatives. Dr. Byrum has extensive experience in mRNA microinjection, cell transplantation, classical experimental embryology, confocal imaging, DIC and fluorescence microscopy, scanning electron microscopy, and transmission electron microscopy. The lab is also exploring other areas, such as circadian control in cnidarians and nuclear transport proteins in the sea urchins. Recent projects include the following:
Investigating the formation of muscle in Lytechinus variegatus
Although much is known about the molecular interactions regulating early formation of endomesoderm in sea urchin embryos, much less is known about the mechanisms regulating specification and differentiation of endodermal and mesodermal derivatives later in development. Our studies focus on the formation of one subgroup of late mesoderm, muscle. The phylogenetic position of our subject, the echinoderm Lytechinus variegatus (an East coast species commonly known as the green sea urchin), makes it an attractive model for studying the evolution of muscle formation. As a basal deuterostome, L. variegatus is a valuable intermediate between the vertebrate phyla and more pleisiomorphic groups such as the Cnidaria. We have successfully isolated markers of muscle formation in this species and are currently exploring functional roles of several myoregulatory transcription factors. This work will provide critical information necessary to understand how roles of these molecules have changed over the course of metazoan evolution.
Circadian control in the sea anemone Nematostella vectensis
In a collaborative research project with Dr. Beth Meyer-Bernstein’s lab, we have been investigating the circadian systems regulating daily cycles in the starlet sea anemone, Nematostella vectensis. Control of the circadian cycles has been extensively studied in vertebrates and flies, but much less is known about the circadian systems of marine invertebrates. Using an automated environmentally controlled chamber, we have established that N. vectensis has a light-entrainable circadian clock and that it may also exhibit a secondary component, an endogenous clock with 12.4 hour frequency. The recently sequenced genome of N. vectensis makes it an especially attractive model for exploring the molecular evolution of circadian behavior, and critical behavioral data are needed to correlate gene expression patterns to specific behaviors. We are currently pursuing work in this area.
The characterization of nuclear transport proteins in Strongylocentrotus purpuratus
Karyopherins are a group of nucleocytoplasmic proteins critical for the transport of molecules into and out of the nucleus. In 2006, the Sea Uchin Consortium detected approximately 23,000 genes in the genome of the purple sea urchin, Strongylocentrotus purpuratus. Although most gene families were clearly annotated, the karyopherin-a and karyopherin-b families were not. In the literature, we have encountered only one publication (Song and Wessel, 2007) that confirms expression of a karyopherin (exportin-5) in the developing sea urchin. To better characterize the diversity of karyopherins present in the sea urchin genome, we used reciprocal blasting and phylogenetic analysis to identify likely homologues of the human karyopherins. Expression analysis also confirmed that several of these nuclear transport proteins are differentially expressed during early development in S. purpuratus. We are continuing to examine the temporal distribution of karyopherins during sea urchin embryogenesis and hope to learn more about roles of these genes during development.
Courses Taught
BIO 305: Genetics
BIO 423/623: Introduction to Genomics
Publications
Byrum, CA. 2012 (In Press). A gathering of minds: expanding understanding of the origins of biological diversity and the evolution of developmental mechanisms. EvoDevo.
Hendrix, W, CA Byrum, E Meyer-Bernstein. In Revision. Circadian behavior of the starlet sea anemone, Nematostella vectensis. PLoS One.
Byrum, CA, R Xu,, JM Bince, DR McClay, & AH Wikramanayake. 2009. Blocking Dishevelled signaling in the noncanonical Wnt pathway in sea urchins disrupts endoderm formation and spiculogenesis, but not secondary mesoderm formation. Dev Dynamics, 238(7): 1649-1665.
Byrum, CA, KD Walton, AJ Robertson, S Carbonneau, RT Thomason, JA Coffman, & DR McClay. 2006. Protein tyrosine and serine-threonine phosphatases in the sea urchin, Strongylocentrotus purpuratus: Identification and potential functions. Developmental Biology, 300(1): 194-218.
Croce, JC, S-Y Wu, C Byrum, R Xu, L Duloquin, AH Wikramanayake, C Gache, & DR McClay. 2006. A genome-wide survey of the evolutionarily conserved Wnt pathways in the sea urchin Strongylocentrotus purpuratus. Developmental Biology, 300(1): 121-31.
Sodergren, E. & The Sea Urchin Genome Sequencing Consortium. 2006. The genome of the sea urchin Strongylocentrotus purpuratus. Science, 314(5801): 941-952.
Byrum, CA, & MQ Martindale. 2004. Gastrulation in the Cnidaria and Ctenophora. In: Gastrulation (Claudio Stern, ed). Cold Spring Harbor Press, Cold Spring Harbor, New York.
Weitzel, H. E., MR Illies, CA Byrum, R Xu, AH Wikramanayake, & CA Ettensohn. 2004. Differential stability of beta-catenin along the animal-vegetal axis of the sea urchin embryo mediated by Dishevelled. Development, 131 (12): 2947-2956.
Wikramanayake, AH, M Hong, PNK Lee, K Pang, CA Byrum, JM Bince, R Xu, & MQ Martindale. 2003. An ancient role for nuclear ß-catenin in the evolution of axial polarity and germ layer segregation. Nature 426(6965): 446-50.
Byrum, CA, & AH Wikramanayake. 2002. Autonomous cell specification: an overview. In: Encyclopedia of Life Sciences. Nature Publishing Group, London.
Byrum, CA. 2001. An analysis of hydrozoan gastrulation by unipolar ingression. Developmental Biology, 240(2): 627-640.