Biological, Geological, and Environmental Sciences

Dr. Aaron Frederick Severson

Associate Professor
Ph.D., Biology, University of Oregon, 2001
Office Phone: (216) 687-4864
Lab Phone: (216) 687-4821
COSHP Faculty Profile

Research Interests

Education: Ph.D., Biology, University of Oregon, 2001

B.S., Zoology, Molecular Biology, University of Wisconsin, 1994

Brief Bio: In all organisms, accurate transmission of the genome during cell division is essential to prevent genetic instability. This is especially true during meiosis, the process that reduces genome copy number, or ploidy, from two in diploid germline stem cells to one in each haploid gamete. Defects in meiosis affect all cells of an embryo and profoundly impact health: it is estimated that over 30% of human zygotes have abnormal chromosomal content at conception, and such aneuploidies are the leading known cause of miscarriages and birth defects. The best known viable aneuploidy, trisomy 21, causes Down syndrome. I use a microscopic roundworm called Caenorhabditis elegans to study how gametes inherit exactly one copy of every chromosome. My research interests encompass events that occur early in meiosis, such as DNA replication, generation of sister chromatid cohesion, homolog pairing, and crossover recombination, as well as those that occur late in meiosis to establish the unique pattern of chromosome segregation that occurs during meiosis and is crucial for the reduction of ploidy. Because the mechanism of meiosis is widely conserved among eukaryotes, the knowledge we generate from our studies of the lowly worm is relevant to understanding normal gametogenesis in humans, as well as the errors in this process that underlie reproductive disease.

Honors and Awards: Helen Hay Whitney Foundation Postdoctoral Fellowship, 2003-2006

American Society for Cell Biology Predoctoral Student Travel Award, 1999

John O. Ward Scholarship, 1990-1994

Dean's List, University of Wisconsin, 1990 and 1992

Professional Affiliations: American Society for Cell Biology

Genetics Society of America

Professional Experience: Assistant Professor, Cleveland State University, BGES Department Postdoctoral Researcher, University of California - Berkeley, MCB Department


Research Articles

Severson, A.F., L. Ling, V. van Zuylen, and B.J. Meyer. 2009. The axial element protein HTP-3 promotes cohesin loading and meiotic axis assembly in C. elegans to implement the meiotic program of chromosome segregation. Genes Dev. 23:1763-1778.

Chan, R.C.*, Severson, A.F.*, and B.J. Meyer. 2004. Condensin restructures chromosomes in preparation for meiotic divisions. J. Cell Biol. 167:613-625. * co-first author paper

Severson, A.F., and B. Bowerman. 2003. Myosin and the PAR proteins polarize microfilament-dependent forces that shape and position mitotic spindles in C. elegans. J. Cell Biol. 161:21-26.

Severson, A.F., D.L. Baillie, and B. Bowerman. 2002. A Formin Homology protein and a Profilin are required for cytokinesis and Arp2/3-independent assembly of cortical microfilaments in C. elegans. Current Biol. 12:2066-2075.

Hamill, D.R., A.F. Severson, J.C. Carter, and B. Bowerman. 2002. Centrosome maturation and mitotic spindle assembly in C. elegans require SPD-5, a protein with multiple coiled-coil domains. Dev. Cell. 3:673-684.

Severson, A.F., D.R. Hamill, J.C. Carter, J. Schumacher, and B. Bowerman. 2000. The Aurora-related Kinase AIR-2 recruits ZEN-4/CeMKLP1 to the mitotic spindle at metaphase and is required for cytokinesis. Curr. Biol. 10:1162-1171.

Swan, K.A., A.F. Severson, J.C. Carter, P.R. Martin, H. Schnabel, R. Schnabel, and B. Bowerman. 1998. cyk-1: a C. elegans FH gene required for a late step in embryonic cytokinesis. J. Cell Sci. 111:2017-2027.

Review Articles:

Wood, A.J.*, A.F. Severson*, and B.J. Meyer. 2010. Condensin and cohesin complexity: the expanding repertoire of functions. Nat. Rev. Genet. 11:391-404. * co-first author paper

Severson, A.F. and B. Bowerman. 2002. Cytokinesis: closing in on the central spindle. Dev. Cell. 2:4-6.

Bowerman, B. and A.F. Severson. 1999. Cell Division: Plant-like properties of animal cell cytokinesis. Curr. Biol. 9: R658-660.

Lab Members:

Liz Tracey, Predoctoral student

Dan Benchek, Predoctoral student

Brendan Skrtic, Undergraduate