The chromosome field

摘要

The distribution of seven different chromosomal properties is described. Non-disjunction of B chromosomes in seven species of Gramineae shows a very regular location which depends on the position of the kinetochore and the telomeres. This property is one of the best examples of the interactions extending along the length of the chromosome, demonstrating how the chromosome field determines the location and expression of a specific genetic property.In rye, the distance between the kinetochore and the locus of non-disjunction comprises about 78 times 106 nucleotide pairs. This means that the effect of the centromere extends along the chromosomal DNA for at least this distance.Chiasmata in Fritillaria meleagris show an optimal distribution which also appears at a constant distance from the kinetochore. The kinetochore—chiasmata distance is about 2.5 μm. irrespective of arm-length. The “fluffy” loops of lampbrush chromosomes of Ambystoma also have a similar distribution as well as the Giemsa banding patterns described in the Triturus species. The distribution of four other chromosome properties, including chromosome breaks in humans, is described and its relation to the interactions established within the chromosome field is discussed.