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Cellulose‐synthesizing terminal complexes and microfibril structure in the brown alga Sphacelaria rigidula (Sphacelariales, Phaeophyceae) *
Author(s) -
Tamura Hiroshi,
Mine Ichiro,
Okuda Kazuo
Publication year - 1996
Publication title -
phycological research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.438
H-Index - 44
eISSN - 1440-1835
pISSN - 1322-0829
DOI - 10.1111/j.1440-1835.1996.tb00039.x
Subject(s) - microfibril , cellulose , cell wall , ribbon , fibril , materials science , biology , biophysics , botany , crystallography , composite material , chemistry , biochemistry
SUMMARY The brown alga Sphacelaria rigidula Kützing synthesizes cellulose microfibrils as determined by CBH I‐gold labeling. The cellulose microfibrils are thin, ribbon‐like structures with a uniform thickness of about 2.6 nm and a variable width in the range of 2.6‐30 nm. Some striations appear along the longitudinal axis of the microfibrils. The developed cell wall in Sphacelaria is composed of three to four layers, and cellulose micro‐fibrils are deposited in the third layer from the outside of the wall. A freeze fracture investigation of this alga revealed cellulose‐synthesizing terminal complexes (TCs), which are associated with the tip of microfibril impressions in the plasmatic fracture face of the plasma membrane. The TCs consist of subunits arranged in a single linear row. The average diameter of the sub‐units is about 6 nm, and the intervals between the neighboring subunits, about 9 nm, are relatively constant. The number of subunits constituting the TC varies between 10 and 100, so that the length of the whole TC varies widely. A model that has been proposed for the assembly of thin, ribbon‐like microfibrils was applied to microfibril assembly in Sphacelaria.