A crucial aspect of gene function is the proper quantitative, temporal, and tissue-specific regulation of transcription. Much of this information is encoded by regulatory sequences that are included within individual genes. Other information is derived from the relationship between the gene and its chromosomal context. My lab is interested in the mechanisms by which genes are controlled using epigenetic mechanisms. To this end, I am using the maize R locus and molecular genetic analysis to elucidate components of gene regulation including: (1) gene structure versus function and (2) the role of imprinting, gene copy number and DNA modification on gene expression.
The R locus is unique because of the ease of mutant selection and the fact that subtle changes in expression produce visibly different phenotypes. Differential patterns of cytosine methylation are determined by the number of genes within R allele complexes; modification in turn modulates R gene expression in allele-specific silencing called paramutation. Paramutation is regulated by small interferring RNA (RNAi). Genomic imprinting (differential allele expression determined by parental allele source) is another level by which gene expression is regulated.
My laboratory uses molecular analysis to determine the relationship between the structures in R gene regulatory regions and the complex array of behaviors that are observed for R alleles. I am also using genomic analysis and data mining to isolate genomic clones of maize genes (the mdr gene family) that regulate genomic imprinting. These genes will be instrumental in determining the steps at which imprinting is controlled in plants.
1. Alleman, M., Sidorenko, L., Seshadri, V., McGinnis, K., Dorweiler, J. E., White, J., Sikkink, K., and Chandler, V. L. (2006) An RNA-dependent RNA polymerase is required for paramutation in maize. Nature 442: 295-298.
2. Alleman, M. and J. Doctor, (2000) Genomic imprinting in plants: observations and evolutionary implications. Plant Molec. Biol. 43: 147-161.
3. Liu, Y., M. Alleman, and S. R. Wessler, (1997) A Ds insertion alters the nuclear localization of the maize transcriptional activator R. Proc. Natl. Acad. Sci. USA 93: 7816-7820.
4. Eggleston, W. B., M. Alleman, and J. L. Kermicle, (1995) Molecular organization and germinal instability of R-stippled maize. Genetics 141: 347-360.
5. Kermicle, J. L., M. Alleman, and W. B. Eggleston, (1995) Organization of paramutagenicity in R-stippled maize R gene. Genetics 141: 361-372.
6. Alleman, M. and J.L. Kermicle, (1993) Somatic variegation and germinal mutability reflect the position of transposable element Dissociation within the maize R gene. Genetics 135: 189.
7. Robbins, T.P., E. L. Walker, J. L. Kermicle, M. Alleman, and S. L. Dellaporta, 1991 Meiotic instability of the R-r complex arising fromdisplaced intragenic exchange and intrachromosomal rearrangement. Genetics 129: 271-283.
8. Kermicle, J.L. and M. Alleman, (1990) Gametic imprinting in maize in relation to the angiosperm life cycle. Development Suppl. 9-14.
9. Kermicle, J.L., M. Alleman and S.J. Dellaporta, (1989) Sequential mutagenesis of a maize gene using the transposable element Dissociation. Genome 31: 712-716.
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Biology Honors Program
Office Phone: 412.396.1660
Email: alleman@duq.edu
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