100. Summary
Wounding cells of Boergesenia forbesii
(Harvey) Feldmann induces the synchronous formation of numerous
protoplasts which synthesize large cellulose microfibrils within
2-3 hours after wounding. The microfibrils appear to be assembled
by linear terminal synthesizing complexes (TCs). TC subunits
appear on both E- and P-faces of the plasma membrane, thus suggesting
the occurrence of a transmembrane complex. The direction of microfibril
synthesis is random during primary wall assembly and becomes ordered
during secondary wall assembly. The average density of TCs during
secondary wall deposition is 1.7/m2, and the average
length of the TC is 510 nm. TC organization is similar to that
of Valonia macrophysa, however, the larger TCs of Boergesenia
(510 nm vs. 350 nm) produce correspondingly larger microfibrils
(30 nm vs. 20 nm). The effects of a fluorescent brightening agent
(FBA), Tinopal LPW, on cell wall regeneration of Boergesenia
protoplasts was investigated. The threshold level of Tinopal
LPW for interfering with microfibril assembly is 1.5 M. At 95
M Tinopal (for short periods up to 15 minutes), microfibril impressions
have atypical spherical impressions at their termini. At longer
incubations (24 hours), TCs and microfibril impressions are absent.
When washed free of Tinopal, the protoplasts eventually resume
normal wall assembly; however, TCs do not reappear until at least
30 minutes after the removal of Tinopal. In consideration of
the presence of ordered TCs before FBA treatment, their random
distribution upon recovery implies an intermediate stage of assembly
or possibly de novo synthesis.