The Simmons lab is studying transposable genetic elements -- transposons -- > in Drosophila melanogaster. These elements are structurally and functionally diverse, and constitute approximately 15% of the Drosophila genome. Collectively, they are responsible for a large fraction of spontaneous mutations and chromosome rearrangements, and some are related to the vertebrate retroviruses, including those that cause human disease. Although a few transposons may perform useful functions in a genome, most seem to be little more than genetic parasites.
The principal focus of Simmons' research is the regulation of the P family of transposons in Drosophila. This transposon family is present in all natural populations, where it is essentially quiescent. However, in crosses between wild and laboratory strains, the P family is activated by a P-encoded enzyme called the transposase. This enzyme recognizes sequences near the ends of each element and catalyzes movement. A basic question is why this movement does not occur in natural populations. Recent analyses have indicated that P elements inserted near the ends of chromosomes play an important role in the regulation of the P transposon family, possibly by transferring a repressive chromatin imprint to other P elements or by triggering an RNA interference pathway that destroys P element RNA. These possibilities are being investigated using a combination of molecular and genetic techniques.
Selected Publications (Pubmed Search)
Jensen, P. A., J. R. Stuart, M. P. Goodpaster, J. W. Goodman and M. J. Simmons, 2008 Cytotype regulation of P transposable elements in Drosophila melanogaster: repressor polypeptides or piRNAs? Genetics 179: 1785-1793.
Cross, E. W. and M. J. Simmons, 2008 Does RNA interference influence meiotic crossing over in Drosophila melanogaster? Genet. Res. Camb. 90: 253-258.
Paterson , J., M. J. Simmons, and K. O’Hare, 2007 Transcription of the singed-weak mutation of Drosophila melanogaster: elimination of P-element sequences by RNA splicing and repression of singed transcription in a P genetic background. Molec. Genetics and Genomics. Jul;278(1):53-64.
Haley, K. J., J. R. Stuart, J. D. Raymond, J. B. Niemi, and M. J. Simmons. (2005) Impairment of cytotype regulation of P-element activity in Drosophila melanogaster by mutations in the Su(var)205 gene. Genetics 171: 583-595.
Simmons, M. J., Raymond, J. D., Niemi, J. B., Stuart, J. R. and Merriman, P. J. (2004) The P cytotype in Drosophila melanogaster: a maternally transmitted regulatory state of the germ line associated with telomeric P elements. Genetics 166:243-254
Niemi, J. B., J. D. Raymond, Patrek, R. and Simmons, M. J. (2004) Establishment and maintenance of the P cytotype associated with telomeric P elements in Drosophila melanogaster. Genetics 166:255-264.
Simmons, M. J., K. J. Haley, C. D. Grimes, J. D. Raymond, and J. B. Niemi, (2002) A hobo transgene that encodes the P element transposase in Drosophila melanogaster: autoregulation and cytotype control of transposase activity. Genetics 161: 195-204.
Simmons, M. J., K. J. Haley, C. D. Grimes, J. D. Raymond, and J. C. L. Fong, (2002) Regulation of P element transposase activity in Drosophila melanogaster by hobo transgenes that contain KP elements. Genetics 161: 205-215.
Recent Book Published:
Snustad, D.P., and M.J. Simmons, (2006) Principles of Genetics Fourth Edition. John Wiley & Sons.