Research Summary
An aneuploid cell is one that has extra or missing chromosomes. Aneuploidy results from errors in distribution of chromosomes to daughter cells during mitosis or meiosis. Mitotic errors causing aneuploidy are common in cancer cells. Errors causing aneuploidy also are quite common in meiosis, resulting in fetal loss or birth defects, the best-known example being Down’s Syndrome (Trisomy 21).
The proper distribution of partner chromosomes to opposite poles of the cell depends on the correct attachment of chromosomes to spindle microtubules. Normally a chromosome has all its microtubules directed toward one pole, and its partner has all its chromosomes directed toward the opposite pole.
We are studying what happens when a chromosome either has (1) microtubules directed toward both poles, or (2) all its microtubules directed toward the same pole as its partner. Such chromosomes often behave in ways not predicted by classical ideas regarding force deployment in the spindle. We are correlating such behaviors with microtubule dynamics to better understand how the spindle functions. Results also are revealing which malorientations cause aneuploidy, how malorientations can be corrected, and how cells can avoid aneuploidy even when unusual chromosome orientations persist.
Selected Publications
- Janicke, M. A. and J.R. Lafountain, Jr. 1982. Chromosome segregation in crane-fly spermatocytes: Cold treatment and cold recovery induce anaphase lag. Chromosoma 85:619-631.
- Janicke, M. A. and J. R. Lafountain, Jr. 1984. Malorientation of half-bivalents at anaphase: Analysis of autosomal laggards in untreated, cold-treated and cold-recovering crane-fly spermatocytes. J. Cell Biol 98:859-869.
- Scarcello, L. A., M. A. Janicke and J. R. LaFountain, Jr., 1986. Kinetochore microtubules in crane-fly spermatocytes: Untreated, 2oC-treated, and 6oC-grown spindles. Cell Motility and the Cytoskeleton 6(4)428-438.
- Janicke, M. A. and J. R. LaFountain, Jr. 1986. Bivalent orientation and behavior in crane-fly spermatocytes recovering from cold exposure. Cell Motility and the Cytoskeleton 6:492-501.
- Janicke, M.A. and J. R. LaFountain, Jr., 1989. Centromeric dots in crane-fly spermatocytes: Meiotic maturation and malorientation. Chromosoma 98:358-367.
- LaFountain, J. R., Jr. M. A. Janicke, R. Balczon, and G. K. Rickards. 1992. Cytochalasin induces abnormal anaphase in crane-fl spermatocytes and causes altered distribution of actin and centromeric antigens. Chromosoma 101:425-441.
- Janicke, M. A., L. Lasko, R. Oldenbourg, and J. R. LaFountain, Jr. 2007. Chromosome malorientations after meiosis II arrest cause nondisjunction. Mol. Biol. Cell 18:1645-1656; published online before print as 10.1091/mbc.E06-!0-0963
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