Epigenetics of Reproduction in Animals - Building the Most Complex Structure on Earth - page 69

Figure 2.3 Visualization of an inverted ciliary row. In the left panel, the arrow points
to a discontinuity in the cortical pattern. In the right panel, the enlargement around this
discontinuity shows the direction of the ciliary rootlets, which run downward and to the right
of the observer for inverted rows and run upward and to the left of the observer for normally
oriented rows. Bar: 10 mm.
Source : Courtesy of F. Ruiz ( Beisson, 2008 ).
And his former student, Nanney, stated:
A cell possesses (at least) two classes of structural information: information linearly
coded in nucleic templates, either nuclear or cytoplasmic, and information encoded
in supramolecular organization.
Nanney (1966)
Based on present knowledge, we may interpret cortical inheritance and the “struc-
tural memory” of Paramecium and other ciliary unicellulars as functions of centriole/
basal bodies, i.e., of their capability to self-replicate genome independently.
Despite its great theoretical importance and implications for biology, cortical
inheritance was overshadowed by the overwhelming success of the genecentric view.
It now seems to be escaping that shadow.
The discovery of the DNA methylation in 1975, independently by the British biol-
ogist Robin Holliday and his student John Pugh (Holliday and Pugh, 1975) and by
Arthur D. Riggs (Riggs, 1975) in California, triggered a snowball effect on epige-
netic research.
Neural Origin of Epigenetic Information in Epigenetic Structures
Under the umbrella of epigenetic information are understood changes in DNA meth-
ylation/demethylation ( Figure 2.4 ), histone marks leading to chromatin remodeling,
and changes in the patterns of miRNA expression.