Premium
A Freeze‐Fracture Study of the Microcyst Wall, Plasma Membrane, and Intramembrane Components of Physarum polycephalum 1
Author(s) -
HOGAN JAMES C.,
TURNER HENRIE M.
Publication year - 1982
Publication title -
the journal of protozoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.067
H-Index - 77
eISSN - 1550-7408
pISSN - 0022-3921
DOI - 10.1111/j.1550-7408.1982.tb05412.x
Subject(s) - physarum polycephalum , membrane , fibril , protoplasm , cell membrane , cell wall , biophysics , cell , biology , extracellular , cytoplasm , population , microbiology and biotechnology , biochemistry , demography , sociology
. Freeze‐cleave replicas of encysted cells of the myxamoebae of Physarum polycephalum were examined to determine the intrawall substructure and to compare the intramembrane structural components. Cleaved areas of the cyst wall revealed a laminated substructure devoid of the macromolecular interruptions (intramembrane particles or IMP) visible in the cleaved cell membranes. The cyst wall adjacent to the cell membrane appears laminated, and a loose branching network of fibers and fibrils occurs at the wall periphery. The absence of intrawall particles is interpreted as a lack of protein or polypeptide components, thus suggesting additional support for the conclusion that polysaccharides are the major wall constituents. When cleaved cell membranes of encysted cells were examined, more intramembrane particles per unit area were observed on the extracellular membrane leaflet than on the protoplasmic membrane leaflet. In addition, homogeneous as well as aggregated particle distributions were visible on cleaved membrane leaflets. Moreover, the presence of aggregated and unaggregated particles on the same membrane leaflets similarly suggests asynchrony of the cell population. This paper examines and compares biological processes involving the cell membrane that may be related to different stages in the cell cycle or to periods of temporary stasis during the cell cycle.