Spindles (green) in Axs mutants (right) are barrel shaped and lose symmetric chromosome (blue) alignment.
Hawley/Macmillan
Arecent report by Joseph Kramer and Scott Hawley (Stowers Institute for Medical Research, Kansas City, MO) demonstrates that a widely conserved protein regulates meiotic spindle formation from a peculiar membranous structure surrounding the spindle.Nearly two decades ago, sheath-like membranes resembling the endoplasmic reticulum (ER) were seen enclosing the meiotic spindle in wolf spider spermatocytes. The structures have remained mysterious—no function has been assigned to them, and they have not been identified in any other system. Kramer and Hawley have now not only found the sheath in fly oocytes, but also identified the protein Axs as a component of the structure.
Mutations in Axs are known to cause segregation defects in chromosomes that do not crossover during meiosis. The authors cloned the gene and found that Axs is an ER-localized...
