Comparative Aspects of Chromosome Replication in Drosophila and Mammals

Raman, Rajiva; Lakhotia, S. C.

doi:10.1007/978-3-662-10621-1_6

Cited by 6 publications

(1 citation statement)

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“…The greatest difference between the developmental systems of Drosophila and man is in the number of mitoses required for forming and maintaining the organism. Only about 20 mitoses are needed to provide the approximately 106 somatic cells in an adult Drosophila and there is no DNA replication in the adult, except in germ cells (Raman & Lakhotia 1989). In man, in the order of 106 mitoses per second occur, leading to an estimate of 1016 mitoses in the course of a lifetime (Alberts et al 1983).…”

Section: Cell Memory and D Rosophilamentioning

confidence: 99%

DNA methylation and late replication probably aid cell memory, and type I DNA reeling could aid chromosome folding and enhancer function

Riggs

1990

Phil. Trans. R. Soc. Lond. B

122

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DNA methylation in mammals is reviewed, and it is concluded that one role of methylation is to aid cell memory, which is defined as the ability of mitotically derived progeny cells to remember and re-establish their proper cellular identity. Methylation of X-linked CpG-rich islands probably stabilizes X-chromosome inactivation, but other mechanisms appear to be involved. Late replication is discussed as a key ancestral mechanism for X inactivation, and it is emphasized that early and late replication domains may each be self perpetuating. Therefore, early-late replication timing becomes another strong candidate mechanism for cell memory. A chromosome-loop folding enigma is discussed, and it is concluded that special mechanisms are needed to explain the formation and maintenance of specific looped domains. DNA reeling, such as done by type I restriction-modification enzymes, is proposed to provide this special mechanism for folding. DNA reeling mechanisms can help to explain the cis-spreading of X-chromosome inactivation as well as long-range action by enhancers.

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Section: Cell Memory and D Rosophilamentioning

confidence: 99%