T-1, a mitotic arrester, alters centrosome configurations in fertilized sea urchin eggs.
T-1 induces modifications in the shape of the centrosome at division in fertilized eggs of the North American sea urchin, Lytechinus pictus. Phase contrast microscopy observations of mitotic apparatus isolated from T-1-treated (1.7-8.5 microM) eggs at first division shows that the centrosomes already begin to spread or to separate by prophase and that the mitotic spindle is barrel-shaped. When eggs are fertilized with sperm that have been preteated with T-1, the centrosomes become flattened; the spindles are of normal length. Immunofluorescence microscopy using an anti-centrosomal monoclonal antibody reveals that T-1 modifies the structure of the centrosome so that barrel-shaped spindles with broad centrosomes are observed at metaphase, rather than the expected focused poles and fusiform spindle. Higher concentrations of T-1 induce fragmentation of centrosomes, causing abnormal accumulation of microtubules in polar regions. These results indicate that T-1 directly alters centrosomal configuration from a compact structure to a flattened or a spread structure. T-1 can be classified as a new category of mitotic drugs that may prove valuable in dissecting the molecular nature of centrosomes.
Sugashima Marine Biological Laboratory, Nagoya University, Mie, Japan.
T J
TJ
Itoh
H
H
Schatten
G
G
Schatten
D
D
Mazia
A
A
Kobayashi
H
H
Sato
D000818:Animals; D000911:Antibodies, Monoclonal; D002503:Centromere / Q000187:drug effects*; D002875:Chromosomes / Q000187:drug effects*; D005306:Fertilization; D005455:Fluorescent Antibody Technique; D008856:Microscopy, Fluorescence; D008938:Mitosis / Q000187:drug effects*; D010063:Ovum / Q000187:drug effects* / Q000648:ultrastructure; D012118:Resorcinols / Q000494:pharmacology; D012617:Sea Urchins; D008941:Spindle Apparatus / Q000187:drug effects
D000911:Antibodies, Monoclonal; D012118:Resorcinols; C011600:2-n-hexyl-5-n-propylresorcinol