Ab. Ilagan et A. Forer, EFFECTS OF ULTRAVIOLET-MICROBEAM IRRADIATION OF KINETOCHORES IN CRANE-FLY SPERMATOCYTES, Cell motility and the cytoskeleton, 36(3), 1997, pp. 266-275
Ultraviolet (UV)-microbeam irradiation of a single kinetochore during
anaphase generally causes all 6 of the half-bivalents in the cell to s
top poleward motion within 1 min after the irradiation. The half-bival
ents regain movement after remaining stopped for an average of 8.7 min
, through different pairs in the same cell can resume at different tim
es. Once movement resumes they usually continue movement until they re
ach the poles. As controls, to see if the effect is due to alteration
of the kinetochore, we irradiated spindle fibers and chromosome arms u
sing the same doses and wavelengths as for kinetochore irradiation. Af
ter spindle fiber irradiation, only the half-bivalent associated with
the irradiated spindle fiber and its partner stop moving poleward whil
e the other half-bivalents in the same cell are not affected. After ir
radiation of a chromosome arm, the movement of the two partner half-bi
valents associated with the irradiated arm either slowed or moved with
unchanged velocity; no other half-bivalents in the cell were affected
. Therefore, only irradiation of a kinetochore stops the movement of a
ll the half-bivalents in the same cell. We suggest that the irradiated
kinetochore sends a ''stop'' signal to the other kinetochores in the
same cell. (C) 1997 Wiley-Liss, Inc.