Composition of the isolated mitotic apparatus: analysis by polyacrylamide gel electrophoresis.

The mitotic apparatus (MA) from zygotes of the sea urchin Strongylocentrotus purpuratus were isolated and the components of the isolated MA were studied using one-dimensional polyacrylamide gel electrophoresis. MA were isolated using two different stabilization media, hexylene glycol and glycerol-dimethylsulphoxide ( MTM ), because previous studies have shown that MA isolated with these solutions have different properties. Both MA have at least 15-20 bands on gels. Whereas a few bands might be unique to one method of isolation, most bands are the same in hexylene glycol MA and MTM MA. Both kinds of MA differ from the general cytoplasm. Detailed descriptions of the appearances of the gels are given. The main difference between the two kinds of MA is in the relative intensities of the bands found in both MA. The physical and chemical properties of MA change during storage. After various durations of storage MA were extracted with 0.5 M KCl: more proteins were extracted from freshly isolated MA than from stored MA. There were changes in extractibility which occurred at the same time as the physiological changes, but the particular changes in hexylene glycol MA were not the same as those in MTM MA. Thus, there is no common denominator that would allow us to say that loss of extractibility is associated with changes in a certain protein of the isolated MA.