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Metaphase Plate
by AKG (elevens_curse)
at September 13th, 2008 (10:31 pm)

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source: A. Desai, Curr. Biol. 10:R508, 2000. (c) Elsevier.
PDF available upon request.

Fluorescence micrograph of the metaphase plate of the mitotic spindle, showing:
red = kinetochores
green = microtubules
blue = chromosomes

This is really a classic image in the field of fluorescence microscopy and one of my favorites. Desai discussed this image in Current Biology in 2000. A few choice excerpts:

"What are they? Kinetochores are protein machines that assemble on centromeric DNA. They attach chromosomes to spindle microtubules, helping them to segregate to daughter cells during cell division with incredible precision. If you ever wondered how your 100 trillion cells end up with 46 — and not 45 or 47 — chromosomes, then kinetochores are (part of) the answer.

Not to be confused with…centrosomes. But it’s OK to confuse them with centromeres. The centromere is the chromosomal domain where the kinetochore is assembled. Genetically speaking, the centromere is the locus necessary to segregate chromosomes. In many species, the centromere is also defined cytologically as the primary constriction visible on condensed chromosomes (the intersection point of the classical X-shaped chromosome) — this is also the point where one observes connection to spindle microtubules. Probably the most commonsensical definition describes the kinetochore as the protein machine that assembles on centromeric DNA during mitosis/meiosis."