Vol. 18, No. 4, 1965 BIOCHEMICAL AND BIOPHYSICAL RESEARCH COMMUNICATIONS
NUCLEOLAR RMA COMPOSITION DURING GROWTH OF THE STARFISH 00 R
JO-E. EdstrZjm
Department of Histology, University of Gothenburg
Present address: Department of Histology, University Sweden.
Received January 19, 1965
Vincent (1952) demonstrated pronounoed differences in base
position between RNA from nuoleoli and cytoplasm in mature
starfish oooytes. Differences in the same dire&ion although of
a smaller siee were found by EdstrLim et al. (1961) in analyses
of younger, but relatively large oocytes. It might seem difficult
to reconcile these findings with all the evidence for a nucleolar
origin of ribosomal RNA (MoConkey and Hopkins, 1964, for ref.),
which constitutes the main RNA fraction in the cytoplasm. It
is obvious, however, that the nucleolar RNA found in full grown
oocytes cannot give a substantial relative contribution in the
cytoplasm on account of the imminent disappearance of the
nucleolus. If there are base changes of the nucleolar RWA during
the end of the life of the nuoleolus , these consequently oannot
be expeoted to be reflected to any larger extent in the composition
of the cytoplasmic RNA, the ribosomal component of
which probably does not turn over (Graham and Siminovitoh, 1957;
Davern and Meselson, 1960; MoMasteACaye, 1960). During earlier
growth stages one would, on the other hand, expect a better
agreement. In order to test this hypothesis microeleotrophoretio
RNA base analyses were carried out on nuoleoli and cytoplasm
isolated from starfish oooytes in early and late growth stages.
WATERIALS AND WETHODS: Small pieces of ovaries were removed from