Oocyte DNA (red) forms a compact karyosome before meiosis (top). In flies that have a mutant NHK-1, the DNA remains near the nuclear envelope (bottom).

In the large volume of an oocyte, chromosomes huddle together before the meiotic spindle forms. Fashioning this huddled mass—called a karyosome—requires that chromosomes first be released from the nuclear envelope, according to results from Lancaster et al.

Because oocytes lack centrosomes, they assemble spindle microtubules from chromatin. By clustering chromosomes together, karyosomes help make sure that only one spindle is generated. Karyosomes don't form in fly oocytes that lack a kinase called NHK-1. In the new work, the authors found that chromosomes in nhk-1 mutant cells made widespread contacts with the nuclear envelope, whereas in normal cells, the karyosome formed away from the envelope.

The group found that an NHK-1 substrate from fly cells was an envelope-associated protein called...

The Rockefeller University Press
2007
The Rockefeller University Press
2007
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