PREPARATION AND CHARACTERIZATION OF PROTOPLASTS OBTAINED FROM THE PRASINOPHYTE SCHERFFELIA DUBIA (CHLOROPHYTA)1

Abstract

The prasinophyte genera Scherffelia and Tetraselmis are the only genera that form a cell wall by an extracellular fusion of scales called a theca. We established a protocol for the production of protoplasts from Scherffelia dubia Pascher emend. Melkonian et Preisig using 3 mM Ellman's reagent (5,5′‐dithio‐bis‐2‐nitrobenozoic acid [DTNB]). Protoplasts analyzed by EM lacked flagella and thecae but were otherwise similar to control cells. In response to treatment with DTNB, many protoplasts synthesized new thecal scales in the Golgi apparatus, indicating that cells attempted to regenerate new cell walls. However, complete regeneration of the thecae only occurred once DTNB was washed out from the medium. At higher DTNB concentrations (5 mM), two protoplasts were found within the parental cell wall and scales accumulated between the plasma membrane of the protoplasts and the original theca but failed to form a new theca.