Swedak J A, Forer A
Biology Department, York University, North York, Ontario, Canada.
J Cell Sci. 1991 Oct;100 ( Pt 2):261-8. doi: 10.1242/jcs.100.2.261.
We have irradiated kinetochores of chromosomes in spermatocytes of crane flies (Nephrotoma abbreviata (Loew)) and Nephrotoma suturalis (Loew), while observing the cells using polarization microscopy. Irradiation of a kinetochore of one sex chromosome with 0.106 ergs microns-2, the minimum dose needed to stop movement, had no effect on the birefringence of the irradiated kinetochore's spindle fibre. Irradiation of the kinetochore of an autosomal half-bivalent in anaphase, with the same dose, had no effect on the birefringence of the irradiated kinetochore's spindle fibre, but nonetheless the anaphase movements of all six autosomal half-bivalents were stopped, temporarily, for up to 20 min. Irradiations of the kinetochores of an autosomal half-bivalent with higher doses (0.301 ergs microns-2) caused loss of birefringence of the irradiated kinetochore's spindle fibre, and the movements of all six autosomal half-bivalents were stopped permanently. We argue that the ultraviolet microbeam differentially affects two functions of the kinetochore: (1) a 'signalling' function, and (2) microtubule attachment, with the signalling function being altered at doses lower than that of microtubule attachment.
我们用紫外线微光束照射了大蚊（Nephrotoma abbreviata (Loew)）和缝斑大蚊（Nephrotoma suturalis (Loew)）精母细胞中染色体的动粒，同时用偏光显微镜观察细胞。用0.106尔格/微米²（停止运动所需的最小剂量）照射一条性染色体的动粒，对被照射动粒的纺锤体纤维的双折射没有影响。用相同剂量照射后期常染色体半二价体的动粒，对被照射动粒的纺锤体纤维的双折射没有影响，但所有六条常染色体半二价体的后期运动都暂时停止了，长达20分钟。用更高剂量（0.301尔格/微米²）照射常染色体半二价体的动粒，导致被照射动粒的纺锤体纤维双折射消失，所有六条常染色体半二价体的运动都永久停止。我们认为紫外线微光束对动粒的两种功能有不同影响：（1）“信号传导”功能，（2）微管附着，信号传导功能在低于微管附着的剂量下就会改变。
