I am reading a paper which discusses Maize Genome Structure. Descriptions of the structure is given in the papers introduction.
I know about heterochromatin "heterochromatin stains intensely, indicating tighter packing. Heterochromatin is usually localized to the periphery of the nucleus"
but, could someone explain what is knob heterochromatin?
Here's a good summary of knobs, which says that they are "typically telomeric," "tandemly repeated DNA sequences [that] appear as distinct, heteropycnotic regions located at certain sites on specific chromosomes and look much like beads on a string" and are involved in:
chromosome breakage and chromatin loss
sex differences in recombination
The introduction to this paper gives some of the same information.
A chromosomal region that can
be identified microscopically as
being darkly stained compared
with surrounding chromatin.
DNA sequence analysis has
shown that knobs often contain
highly repeated DNA
sequences. They were
described initially in the
1930’s by McClintock during
her studies of maize