1995 Fiscal Year Final Research Report Summary
Delineation of DNA Replication Timing within MHC Region by FISH
| Project/Area Number |
06660099
|
|---|
| Research Category |
Grant-in-Aid for General Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Research Field |
応用微生物学・応用生物化学
|
|---|
| Research Institution | Mie University |
|---|
Principal Investigator |
OKURMURA Katsuzumi Mie Univ.Fac.Bioresources, Assoc.Prof., 生物資源学部, 助教授 (30177183)
|
|---|
| Project Period (FY) |
1994 – 1995
|
| Keywords | FISH / MHC / DNA replication / chromosome structure / GC content |
|---|
| Research Abstract |
Fluorescence in situ hybridization (FISH) was used to analyze how the DNA replication timing is related to the genome structure and how the specific genome domains are arranged in the nucleus.
First, we have determined the replication timing pattern of DNA segments over 2Mb within human MHC on HL60 cells. This region is composed of long-range G+C% (GC) mosaic structures related to chromosome bands and a boundary of GC mosaic domains exists between MHC classes II and III.FISH with the elongated chromatin fibers showed that the flanking genome structures of the boundary are strictly consistent with the reported mapping data. This confirmed that HL60 cells may not have large structural abnormality in this region. Multi-color FISH to interphase nuclei was useful to compare the temporal replication timing of two DNA fragments which locate adjacent genomic positions and have a similar replication timing in the cell cycle. By this procedure, it was possible to determine the precise replication timing of each DNA fragment which was randomly selected from MHC region. The fragments at the boundary region were found to relatively replicate latest among all examined. It was also suggested that this region consists of at least two replicon clusters. Interestingly, there is a close correlation between the temporal order of replication and the GC gradient of genome sequences in human MHC on HL60 cells. These results suggested the possibility that replication of DNA in mammalian cell genome reflects GC mosaic domains at the level of genome sequences as well as chromosome bands.
|
