Yi Wei of the Department of Biology, University of Rochester, Rochester,
New York will be giving a talk at the NCBI as advertised below. He is a
postdoctoral candidate at the NCBI. If you would like to speak with him,
please let me know.

David Landsman 435-5981

TITLE:
Phosphorylation of Histone H3 is Required for Proper Chromosome
Condensation and Segregation

ABSTRACT
	Histone H3 phosphorylation has long been correlated with mitosis.  To
study  H3 phosphorylation in vivo, antibodies highly specific for
phosphorylated form of H3 were generated.  Using these antibodies in
eukaryotes ranging from  protozoans to mammalian cells, it was shown that
H3 phosphorylation is associated with mitosis in a fashion that closely
coincides with mitotic chromosome condensation.  These observations suggest
a strong correlative, but not necessarily causative relationship between H3
phosphorylation and mitotic chromosome condensation.  To better understand
the function of H3 phosphorylation in vivo, strains of Tetrahymena in which
a mutant H3 gene (S10A) was the only gene encoding the major H3 protein
were created.  Although both micronuclei and macronuclei contain H3 in
typical nucleosomal structures, defects in nuclear divisions were
restricted to mitotically-dividing micronuclei; macronuclei, which are
amitotic, showed no defects.  Strains lacking phosphorylated H3 showed
abnormal chromosome segregation, resulting in extensive chromosome loss
during mitosis.  During meiosis, micronuclei underwent abnormal chromosome
condensation and failed to faithfully transmit chromosomes.  These results
demonstrate that H3 Ser10 phosphorylation is causally linked to chromosome
condensation and segregation in vivo and is required for proper chromosome
dynamics.