The role of the chromosome axis

摘要

The possible origin and functions of axis-like elements observed in eukaryotic chromosomes are discussed. On the basis of uninemic and binemic models for chromatids two essentially different hypotheses for the origin and the role of the axial element can be suggested: (i) Core fibrils are synthesized by extra replication of the axial parts of uninemic chromatids for the coiling phase of chromosomes, and the core fibrils are eliminated before the next S-phase. (ii) Core fibrils are differentiated parts of chromosomal DNA. They persist throughout the cell cycle and play an essential role in determination of chromomere sites along the chromosome axis, in segregation of chromosomal DNA, and in the coiling of chromosomes for division. Current cytological evidence seems to support the latter hypothesis of a binemic organization of chromatids.