From equator to pole: splitting chromosomes in mitosis and meiosis

Abstract

During eukaryotic cell division, chromosomes must be precisely partitioned to daughter cells. This relies on a mechanism to move chromosomes in defined directions within the parental cell. While sister chromatids are segregated from one another in mitosis and meiosis II, specific adaptations enable the segregation of homologous chromosomes during meiosis I to reduce ploidy for gamete production. Many of the factors that drive these directed chromosome movements are known, and their molecular mechanism has started to be uncovered. Here we review the mechanisms of eukaryotic chromosome segregation, with a particular emphasis on the modifications that ensure the segregation of homologous chromosomes during meiosis I.

Restructuring of Holocentric Centromeres During Meiosis in the Plant Rhynchospora pubera

“…In general, every eukaryotic chromosome has a centromere on which the kinetochore complex assembles (Cleveland et al 2003;Burrack and Berman 2012). In most eukaryotes, centromeric nucleosomes contain CENH3 (also known as CENP-A, a histone H3 variant that replaces canonical H3 at the centromere), and usually spans several hundred kilobase pairs often in association with centromere-specific repeats (Steiner and Henikoff 2015).Centromere organization and dynamics vary between mitosis and meiosis (Duro and Marston 2015;Ohkura 2015). During mitosis, sister chromatids are held together by centromere cohesion until metaphase.…”

PGRMC1 and the faithful progression through mitosis and meiosis

“…1 However, mitosis and meiosis share a common event in which the chromosomes align on the metaphase plate and then segregate becoming equally distributed between the resulting daughter cells in mitosis or oocyte and polar body in meiosis. 1 This is because mitosis and meiosis are alternative programs responding to different selective needs that evolved from an eukaryote ancestor.…”

“…1 However, mitosis and meiosis share a common event in which the chromosomes align on the metaphase plate and then segregate becoming equally distributed between the resulting daughter cells in mitosis or oocyte and polar body in meiosis. 1 This is because mitosis and meiosis are alternative programs responding to different selective needs that evolved from an eukaryote ancestor. 2 Regardless of whether chromosomal segregation occurs in somatic cells or germ cells, the chromosomes align along the metaphase plate/spindle apparatus and then faithfully segregate in order to avoid errors in mitosis or meiosis.…”

“…2 Regardless of whether chromosomal segregation occurs in somatic cells or germ cells, the chromosomes align along the metaphase plate/spindle apparatus and then faithfully segregate in order to avoid errors in mitosis or meiosis. 1 Numerous proteins interact with the metaphase plate and/or spindle apparatus and influence chromosomal segregation. 3 Of particular importance are proteins that localize to the mid-zone/mid-body of the spindle apparatus because these proteins ultimately control the final stages of mitosis and meiosis.…”

Plant Cell Division

“…The kinetochore, a fascinating protein complex that facilitates the attachment of spindle microtubules to pull sister chromatids apart during cell division (11), is poorly studied in plant. Kinetochore assembly is initiated by incorporation of the centromeric histone H3 into centromeric nucleosomes (12).…”