Periplasmic Structure in Saccharomyces rouxii (Boutroux), an Osmophil

Abstract

Electron micrographs of ultrathin sections of S. rouxii displayed electrondense, membrane-circumscribed structures between the protoplasmic membrane and the cell wall. These periplasmic bodies were numerous in cells from a 3-day culture and absent or rare in older cells. Periplasmic bodies were fewer and smaller (flattened) in specimens grown in a medium fortified with 10% sucrose; they were not detected in cells grown in 20% sucrose. A brief treatment with ethyl acetate caused the periplasmic bodies of young cells to become electron light. Periplasmic bodies were most prevalent in the regions of the bud scars and were often accommodated within large invaginations in the protoplasmic membrane. In general, conditions which favor the prevalence and electron density of periplasmic bodies are those which also mask the activity of fl-fructofuranosidase in this species.

Isolation and Characterization of Protoplasts from Saccharomyces rouxii

“…Be-cause the effect of reducing agents is on the wall rather than the snail enzyme (10), the requirement at all stages of growth may indicate a somewhat different wall structure for S. rouxii compared with other Saccharomyces species. Periplasmic bodies were first described in intact cells of S. rouxii (3) and have now been observed in spheroplasts and protoplasts. In cross-section some of these vesicular structures appear to be joined to the protoplasmic membrane by a pedicel; others are sufficiently separated from the protoplast to be regarded as probably free even though this interpretation is based on a single plane of section.…”

“…Electron microscopy. The ultrastructure of S. rouxii cells has already been described (3). The hallmark of the species is its propensity for periplasmic bodies.…”

“…Cells and protoplasts were postfixed with 1% osmium tetroxide (overnight at 4°C). The general procedures for embedment, sectioning, and transmission electron microscopy followed previous descriptions (3).…”

Effects of Polyenes, Detergents, and Other Potential Membrane Perturbants on an Osmotolerant Yeast, Saccharomyces rouxii

“…Another unusual feature of S. rouxii is the physically cryptic nature of its P-fructofuranosidase (2, 20), an enzyme generally expressed in yeast species by dint of its location in the periplasmic space (1). Circumstantial evidence lends some support to the location of cryptic ,Bfructofuranosidase in the periplasmic bodies within young cells of S. rouxii (4,5). These vesicular structures are derived from the plasma membrane but remain attached through fine pedicels, thus thwarting separation from protoplasts after cell wall dissolution (4).…”