Project: Research project

Project Details


We will measure the temporal order of replication in several cell lines of
at least 30 different segments of the mouse genome containing several
structural genes including members of the globin and immunoglobulin
multigene families and the genes for alphafeto-protein, albumin, actin,
myosin, ribosomal RNA and dihydrofolate reductase. We will determine the
temporal order of replication of these genes in different cell lines in
which they are active or inactive. The information obtained will help
clarify the apparent relationship between late DNA replication and genetic
inactivity. Criteria for activity in these cells will be the amount of
mRNA sequences present and the accessibility of the genes when nuclei are
incubated with endonucleases. We have determined that an adult alpha-1
globin region replicates early during S in a subcloned Friend murine
erythroleukemia (MEL) cell line. We also have evidence that two
beta-globin gene regions replicate during a defined S phase interval in
this cell line. The temporal replication of these as well as several other
genes will be measured in different murine cell lines to determine the
stringency with which this regulation is maintained. This will provide a
basis for further biochemical studies on the regulation of activation of
specific replicons in mammalian cells. The variable and constant region
genes of the immunoglobulin light and heavy chain gene clusters will be
examined in detail to determine whether related genes are replicated during
the same interval of the S phase. Initial studies will focus on
determining whether the temporal replication of any immunoglobulin genes
occurs during an interval different from the other members of the gene
cluster. Several methods will be used to look for the presence of origins
of replication in well characterized (50-250 kb) regions of the mouse
genome. The relative rates of appearance in the cytoplasm during the cell
cycle in MEL cells will be measured for mRNAs transcribed from genes whose
temporal replications we have determined.
Effective start/end date12/31/8912/31/89


  • Genetics
  • Molecular Biology
  • Cancer Research
  • Oncology


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