spacer gif spacer gif spacer gif spacer gif spacer gif
QUICK SEARCH:   [advanced]


spacer gif
     Home     Help     Feedback     Subscriptions     Archive     Search     Table of Contents    

This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow reprints & permissions
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Sillers, P. J.
Right arrow Articles by Forer, A.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Sillers, P. J.
Right arrow Articles by Forer, A.

Journal of Cell Science, Vol 64, Issue 1 69-88, Copyright © 1983 by Company of Biologists

JOURNAL ARTICLES

Prometaphase forces towards opposite spindle poles are not independent: an on/off control system is identified by ultraviolet microbeam irradiations

PJ Sillers, D Wise and A Forer

Individual spindle fibres in prometaphase spermatocytes of the cricket, Neocurtilla hexadactyla, were irradiated with an ultraviolet microbeam. The stretched heteromorphic bivalent (X2Y) contracted to about 75% of its pre-irradiation length after irradiation of either of its two oppositely directed spindle fibres (i.e., the X2 or Y spindle fibre). The X2Y bivalent also contracted after irradiation of the connection between the kinetochores of the univalent X1 chromosome and the Y chromosome but it did not contract after irradiation of autosomal spindle fibres or of the spindle fibre of the X1 univalent sex chromosome. The spindles sometimes shrank after irradiation, but contraction of the X2Y bivalent was independent of spindle shrinkage. The data strongly suggest that the oppositely directed forces on a bivalent are not independent. One reason is that the X2Y contractions were asymmetrical: during contraction one kinetochore remained fixed in position while the other kinetochore (facing the opposite pole) moved towards the equator. In 75% of the cases the stationary kinetochore was associated with the irradiated spindle fibre. Thus, we suggest that the irradiation of a spindle fibre produces a state analogous to rigor in the irradiated spindle fibre and, because of effects on the control system, produces relaxation of tension in the oppositely directed non-irradiated spindle fibre, so that the kinetochore associated with the non-irradiated spindle fibre moves towards the equator. These experiments have identified a control system that coordinates force production to opposite poles.


This article has been cited by other articles:


Home page
 J. Cell Sci.Home page
B Yin and A Forer
Coordinated movements between autosomal half-bivalents in crane-fly spermatocytes: evidence that 'stop' signals are sent between partner half-bivalents
J. Cell Sci., January 1, 1996; 109(1): 155 - 163.
[Abstract] [PDF]


© The Company of Biologists Ltd 1983