STABILITY OF ISOLATED MITOTIC APPARATUS DURING STORAGE.

Mitotic apparatus (MA) were isolated from sea urchin zygotes using various isolation procedures, and various properties of the isolated MA were studied and compared. MA isolated using hexylene glycol had birefringences which depended on the pH of the isolation medium, the lower the pH the higher the MA birefringence. The stability of the MA Birefringence also depended on the pH of the hexylene glycol isolation medium (the lower the pH the slower the rate of decay of birefringence), as did the final birefringence reached after prolonged storage. MA isolated using glycerol-dimethylsulphoxide (MTME) had much more stable birefringence than MA isolated using hexylene glycol; their birefringence decay rates were about 1000 times slower than those of MA isolated using hexylene glycol. Birefringence which remained after extraction of MA with H O, or 0.5 M KC1 was also studied; the results depended on the MA isolation medium, on the medium the MA were stored in, and on the amount of time the MA were stored after isolation, as described in detail in the text. These results are discussed, and it is suggested that several components (including, perhaps, oriented ribosomes) contribute to birefringence of isolated MA.