Sarah Elgin

Title:	Viktor Hamburger Distinguished Professor in Arts & Sciences Professor of Biology Professor of Education Professor of Genetics
Degree:	PHD, California Institute of Technology BA, Pomona College
Dept:	Biology
Office:	McDonnell Hall 131
Mailbox:	Campus Box 1137 One Brookings Drive St. Louis, MO 63130-4899 Hide Full Mailing Address
Phone:	(314) 935-5348
E-mail:	selgin@wustl.edu

Courses
DNA Science: A Hands-On Workshop; Research Explorations in Genomics

Research Interests
Professor Elgin's lab is interested in the role that chromatin structure plays in gene regulation, both effects from packaging large domains and local effects of the nucleosome array. Working with Drosophila melanogaster, they have used a transposable P element containing a copy of the white gene, a visible marker for gene silencing, and a copy of hsp26 , a well-characterized inducible gene, to examine the effect of insertion into different chromosomal domains. While these genes are fully active in euchromatic domains, silencing (similar to Position Effect Variegation) is observed on insertion into pericentric heterochromatin, telomeres, and sites within the small fourth chromosome. Both changes in the local nucleosome array, and the spatial organization of the nucleus, appear critical in determining gene silencing. While many P element insertion sites on the fourth chromosome induce silencing, others allow full expression; these sites are interspersed, indicating closely interspersed heterochromatic and euchromatic domains. Mapping experiments indicate that heterochromatin formation is targeted by the presence of a repetitious element, 1360, and perhaps by other similar elements. Genetic analysis has shown that heterochromatic silencing is dependent on the RNAi machinery. Work is ongoing to determine the mechanism of heterochromatin targeting, and to analyze the role of critical heterochromatin-associated proteins, including HP1 and HP2.

Selected Publications:

Sun FL, Haynes K, Simpson CL, et al. (2004) cis-Acting determinants of heterochromatin formation on Drosophila melanogaster chromosome four. Mol Cell Bio 24:8210-8220.

Pal-Bhadra M, Leibovitch BA, Gandhi SG, et al. (2004) Heterochromatic silencing and HP1 localization in Drosophila are dependent on the RNAi machinery. Science 303:669-672.

Shaffer, C., Cenci, G., Thompson, B., Stephens, G.E., Slawson, E., Adu-Wusu, K., Gatti, M., and Elgin, S.C.R. (2006) The large isoform of Drosophila melanogaster Heterochromatin Protein 2 plays a critical role in gene silencing and chromosome structure, Genetics 174: 1189-204.

Slawson, E.E., Shaffer, C.D., Malone, C.D., Leung, W., Kellmann, E., Shevchek, R.B., Craig, C.A., Bloom, S., Bogenpohl, J. II, Dee, J., Morimoto, E.T.A., Myoung, J., Nett, A.S., Ozsolak, F., Tittiger, M.E., Zeug, A., Pardue, M.L., Buhler, J., Mardis, E., and Elgin, S.C.R. (2006) “Comparison of dot chromosome sequences from D. melanogaster and D. virilis reveals an enrichment of DNA transposon sequences in heterochromatic domains,” Genome Biology 7: R15.

Haynes, K.A., Caudy, A.A., Collins, L. and Elgin S.C.R. (2006) “Element 1360 and components of the RNAi system contribute to HP1-dependent silencing of a pericentric reporter,” Current Biology 16: 2222-27.