Center for Gene Regulation in Health and Disease (GRHD)

Aaron Severson

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 Caenorhabditis elegans to study how gametes inherit exactly one copy of every chromosome. Because the process of meiosis is widely conserved among eukaryotes, the meiotic mechanisms we identify in the lowly worm are relevant to understanding gametogenesis in humans.

File 05101802-WTMeiosis_Merged-Cropped_timestamp_border_3fps.mp4

  • Fatemah Abed.png
    Fatemah Abed
    Undergraduate Researcher, 2023-24
  • Karli Randau.png
    Karli Randau
    Undergraduate Researcher, 2023-24
  • Taharat.png
    Taharat Khandaker
    Volunteer, 2023-Present
  • Elias Asmar.png
    Elias Asmar
    Undergraduate Honors Student, 2023-24
  • Kaniz Fatemah.png
    Kaniz Fatema
    PhD Rotation Student, 2023-Present
  • Ali Ahsan.png
    Ali Ahsan
    PhD Student, 2017-Present
  • Previous
  • members
  • Kendra Brown Photo
    Kendra Brown
    Undergraduate Honors Student, 2022-23. Subsequently attended MS-Anesthesia program at CWRU.
  • Lexi Knight Photo
    Lexi Knight
    Undergraduate Honors Student, 2022-23. Subsequently attended MS-PA program at Baldwin-Wallace.
  • Andrew Blazer Photo
    Andrew Blazer
    Undergraduate Researcher, 2022-23. Subsequently interned at Dermatology, Surgery & Cosmetics of NE OH
  • Chris Cory
    Chris Cory
    Undergraduate Researcher, 2019. Subsequently received MS in Math from CSU.
  • Swetha
    Swetha Joswala
    PhD Student, 2014-20. Subsequently worked as Scientist I at Tessera Therapeutics, Somerville, MA
  • Samhita Chaudhuri
    Samhita Chaudhuri
    MS Student, 2016-20. Subsequently worked as a Lab Technologist at Fulgent Genetics, Temple City, CA
  • Taylor Schilling
    Taylor Schilling
    MS Student, 2017-2020. Subsequently worked as a Research Technologist at the Lerner Research Institute
  • Urja Patel
    Urja Patel
    Undergraduate Researcher, 2017-19. Subsequently attended Podiatry School.
  • Elijah Smith
    Elijah Smith
    Undergraduate Researcher, 2019. Subsequently worked as ASCP Med Tech at SW General Medical Center in Middleburg Heights, OH
  • Solomiya
    Solomiya Puschak
    Undergraduate Researcher, McNair Scholar, 2017-18. Subsequently worked as a Patient Service Specialist at the Cleveland Clinic.
  • Alexis Brown Photo
    Alexis Brown
    Undergraduate Researcher, 2018. Subsequently, Algae & Zooplankton Taxonomist, Beachwood, OH
  • Emilia Kalutskaya Photo
    Emilia Kalutskaya
    College Credit Plus Researcher, 2018. Subsequently received BS-Pharmaceutical Sci from CSU.
  • Taylor Bhaiji Photo
    Taylor Bhaiji
    NIH/NIDDK STEP-UP High School Scholar, Summer 2018. Subsequently attended Columbia University.
  • Sraavya Anne Photo
    Sraavya Anne
    High School Student, Summer 2018. Subsequently attended NJIT/Rutgers Med School
  • Michael Ribaudo
    Michael Ribaudo
    PhD Rotation Student, 2017
  • Kaveri Khanna
    Kaveri Khanna
    PhD Rotation Student, 2016-17
  • Andrew Brandt photo
    Andrew Brandt
    Postbac Researcher, 2016-17. Subsequently attended MS Program in Biotechnology at Columbia University.
  • Abhishek Ganguly
    Abhishek Ganguly
    PhD Student, 2015-17
  • Dan Benchek, MS
    MS Student, 2012-16
  • Kyle Schroeder
    Undergraduate Researcher, 2014-15. Subsequently attended Medical School at St. George's University.
  • Valerie Sar-Shalom
    Valerie Sar-Shalom
    MS Student, 2015-16
  • Elspeth Mitchell
    Elspeth Mitchell
    Postbacalaureate Researcher, 2013-14. Subsequently attended Vet School at Ohio State University
  • Rachel Winegar
    Rachel Winegar
    Undergraduate Researcher, 2013-14. Subsequently attended Podiatry School at Kent State University
  • Brendan Skrtic
    Undergraduate Researcher, 2013-15
  • Liz Tracey
    MS Student, 2012-14

Research Articles

Farboud, B., A.F. Severson, and B.J. Meyer. 2019. Strategies for efficient genome editing using CRISPRCas9. Genetics 211: 431-457. PDF icon Farboud - 2018 - Genetics.pdf

Hernandez, M.R., M.B. Davis, J. Jiang, E.A. Brouhard, A.F. Severson, and G. Csankovszki. 2018. Condensin I protects meiotic cohesin from WAPL-1 mediated removal. PLoS Genetics 14: e1007382. PDF icon Hernandez - 2018 - PLoS Genet.pdf

Severson, A.F., and B.J. Meyer. 2014. Divergent kleisin subunits of cohesin specify mechanisms to tether and release meiotic chromosomes. eLife 10.7554/eLife.03467. PDF icon Severson - 2014 - eLife.pdf

Schvarzstein, M., Pattabiraman, D., Libuda, D.E., Ramadugu, A., Tam, A., Martinez-Perez, E., Roelens, B., Zawadzki, K.A., Yokoo, R., Rosu, S., Severson, A.F., Meyer, B.J., Nabeshima, K., and A.M. Villeneuve. 2014. DNA helicase HIM-6/BLM both promotes MutSγ-dependent crossovers and antagonizes MutSγ-independent inter-homolog associations during Caenorhabditis elegans meiosis. Genetics, pii: genetics.114.161513. PDF icon Schvarzstein - 2014 - Genetics.pdf

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. PDF icon Severson - 2009 - Genes Dev.pdf

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. PDF icon Chan - 2004 - J Cell Biol.pdf
* 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. PDF icon Severson - 2003 - J Cell Biol.pdf

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. PDF icon Severson - 2002 - Current Biol.pdf

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. PDF icon Hamill- 2002 - Dev Cell.pdf

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. PDF icon Severson - 2000 - Current Biol.pdf

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. PDF icon Swan - 1998 - J Cell Sci.pdf

Invited Review Articles and Book Chapters

Severson, A.F. 2016. Analysis of meiotic sister chromatid cohesion in Caenorhabditis elegans. Methods Mol. Biol. 1515:65-95. PDF icon Severson - 2016 - MiMB.pdf

Severson, A.F., G. von Dassow, and B. Bowerman. 2016. Oocyte meiotic spindle assembly and function. Curr. Top. Dev. Biol. 116:65-98.  PDF icon Severson et al - 2016 - CTDB.pdf

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. PDF icon Wood - 2010 - Nat Rev Genet.pdf
* co-first author paper

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

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