The process of nucleolar vacuolation has been quantitatively studied in root cells of the embryo of Zea mays. During germination, we have estimated the percentage of vacuolated nucleoli, the number of vacuoles per nucleolus and the volume density of the vacuoles, the latter by application of the stereological principles of morphometry. In the dormant embryo, no vacuoles can be detected in the n...

The requirement for a nucleolus in the expression of structural genes of nuclear viruses was examined by means of experiments in which the nucleolus or other parts of the nucleus was inactivated by a microbean of unltraviolet light. These experiments showed that the expression of such genes is not dependent on cucleolar function. This conclusion is discussed in the light of previous experiments...

How the nucleolus is segregated during mitosis is poorly understood and occurs by very different mechanisms during closed and open mitosis. Here we report a new mechanism of nucleolar segregation involving removal of the nucleolar-organizing regions (NORs) from nucleoli during Aspergillus nidulans mitosis. This involves a double nuclear envelope (NE) restriction which generates three NE-associa...

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York, UK, was a good choice for the venue of this workshop because the history of nucleolar research—like the city—falls into distinct eras. Founded by the Romans in 71 AD, York has been occupied at various points in time by the Saxons, Vikings and Normans. Our understanding of the nucleolus has also followed a pattern in which rapid advances have been interspersed with periods of relative dorm...

ADAR1 and ADAR2 are editing enzymes that deaminate adenosine to inosine in long double stranded RNA duplexes and specific pre-mRNA transcripts. Here, we show that full-length and N-terminally truncated forms of ADAR1 are simultaneously expressed in HeLa and COS7 cells owing to the usage of alternative starting methionines. Because the N-terminus of ADAR1 contains a nuclear export signal, the fu...