Elastic tethers remain functional during anaphase arrest in partially-lysed crane-fly spermatocytes, and in non-lysed spermatocytes treated with microtubule inhibitors

Elastic tethers connect corresponding arms (telomeres) of partner chromosomes during anaphase segregation; they exert anti-poleward (backward) forces on the poleward-moving chromosomes. This thesis examined how arresting anaphase chromosomal segregation affected elastic tether function. Various dilutions of a standard immunofluorescent lysis buffer were used to partially lyse anaphase-I spermatocytes of crane flies. Partial cell lysis deactivated the anaphase spindle apparatus and arrested anaphase chromosomal segregation. Elastic tethers remained functional, and backward tether forces acting on chromosomes were able to cause backward chromosomal movements. Backward-moving chromosomes were attached to their kinetochore microtubules (kMTs) which might have been slowing them down. To test whether detaching chromosomes from their kMTs could enable their faster backward movements, anaphase spermatocytes were treated with various microtubule inhibitors to disassemble kMTs. The inhibitors led to anaphase segregation arrest, and backward chromosomal movements. However, the drugs were unable to disassemble the stable, acetylated kMTs, and allow faster backward movements.