74. Willison, J. H. M. and R. M. Brown,
Jr. 1978. A model for the pattern of microfibrils in the cell
wall of Glaucocystis. Planta 141:51-58.
Freeze fracturing of Glaucocystis nostochinearum
Itzigsohn cells during cell wall microfibril deposition indicates
that unidirectionally polarized microfibril ends are localized
in a "zone of synthesis" covering about 30% of the surface
area of the plasma membrane. Within this zone there are about
6 microfibril ends/m2 cell surface. It is proposed
that microfibrils are generated by the passage of their tips over
the cell surface and that the pattern of microfibril organization
at the poles of the cells, in which microfibrils of alternate
layers are interconnected at 3 "rotation centres", results
directly from the pattern of this translation of microfibril tips.
In a model of the deposition pattern it is proposed that the
zone of synthesis may split into 3 sub-zones as the poles are
approached, each sub-zone being responsible for the generation
of one rotation centre. It is demonstrated that the microfibrillar
component of the entire wall could be generated by the steady
translation of the microfibril tips (at which synthesis is presumed
to occur) over the cell surface at a rate of 0.25-0.5 m min-l.
Microcinematography indicates that the protoplast rotates during
cell wall deposition ,and it is proposed that this rotation may
play a role in the generation of the microfibril deposition pattern.