Science Research Ideas
Biology
1999:
It is known that the DNA synthesis in eukaryotic cells initiates in many specific loci of chromosomes. However, the relationship between replication licensing factor and the sites of initiation of replication is unclear. Recent experiments suggested that replication licensing does not take place at specific replication origins. (Rui, Regulation of eukaryotic DNA replication and nuclear structure, 1999)
Although the identification of genetic origins in simple eukaryotic cells has been successful, the search for genetic origin in higher eukaryotes has lagged far behind. The contradictory view of specific sequences for origins has emerged in the literature (Rui, Regulation of eukaryotic DNA replication and nuclear structure, 1999)on studying metazoan DNA replication
Although it is uncertain whether genetic origins of DNA replication exist in higher eukaryotic cells, it has been shown that functional origins of replication do exist in higher eukaryotes. Up to date, there are at least 23 published examples detecting functional origins of replication in metazoan. However, the properties of functional origins in higher eukaryotic cells are still not clear. Various techniques that label nascent DNA strands and relate them to their sites of origin have often defined the function origin to a restricted region (down to 0.5Kb). (Rui, Regulation of eukaryotic DNA replication and nuclear structure, 1999)
The concept of the replication factory is not easily reconciled with the traditional view of the replication machinery. Also, it is difficult to explain how replication proceeds in cell free replication systems (such as SV40 virus in vitro replication system) where no nuclear matrix exists. Although no clear answer has come out yet, some clues are emerging from the experiments. It is known that unwinding of SV40 viral origin of replication is the first step of initiation of DNA replication, which is carried out by SV40 T-antigen. SV40 T-antigen unwinding experiment under in vitro condition showed that two T-antigen hexamers form a double-hexamer complex which unwinds bidirectionally the double strand DNA and results in the extruded loops of unwound single strand DNA. (Rui, Regulation of eukaryotic DNA replication and nuclear structure, 1999)
How does the nuclear structure participates in the regulation of DNA replication will become a hot topic in the future. (Rui, Regulation of eukaryotic DNA replication and nuclear structure, 1999)
It is known that the DNA synthesis in eukaryotic cells initiates in many specific loci of chromosomes. However, the relationship between replication licensing factor and the sites of initiation of replication is unclear. Recent experiments suggested that replication licensing does not take place at specific replication origins. (Rui, Regulation of eukaryotic DNA replication and nuclear structure, 1999)
Although the identification of genetic origins in simple eukaryotic cells has been successful, the search for genetic origin in higher eukaryotes has lagged far behind. The contradictory view of specific sequences for origins has emerged in the literature (Rui, Regulation of eukaryotic DNA replication and nuclear structure, 1999)on studying metazoan DNA replication
Although it is uncertain whether genetic origins of DNA replication exist in higher eukaryotic cells, it has been shown that functional origins of replication do exist in higher eukaryotes. Up to date, there are at least 23 published examples detecting functional origins of replication in metazoan. However, the properties of functional origins in higher eukaryotic cells are still not clear. Various techniques that label nascent DNA strands and relate them to their sites of origin have often defined the function origin to a restricted region (down to 0.5Kb). (Rui, Regulation of eukaryotic DNA replication and nuclear structure, 1999)
The concept of the replication factory is not easily reconciled with the traditional view of the replication machinery. Also, it is difficult to explain how replication proceeds in cell free replication systems (such as SV40 virus in vitro replication system) where no nuclear matrix exists. Although no clear answer has come out yet, some clues are emerging from the experiments. It is known that unwinding of SV40 viral origin of replication is the first step of initiation of DNA replication, which is carried out by SV40 T-antigen. SV40 T-antigen unwinding experiment under in vitro condition showed that two T-antigen hexamers form a double-hexamer complex which unwinds bidirectionally the double strand DNA and results in the extruded loops of unwound single strand DNA. (Rui, Regulation of eukaryotic DNA replication and nuclear structure, 1999)
How does the nuclear structure participates in the regulation of DNA replication will become a hot topic in the future. (Rui, Regulation of eukaryotic DNA replication and nuclear structure, 1999)
