Glycol-Cleavage Oxidation

Ultrastructural analysis of cell fusion in yeast

The process of creating a single cell from two progenitor cells requires molecular precision to coordinate the events leading to cytoplasmic continuity while preventing lethal cell lysis. Cell fusion characteristically involves the mobilization of fundamental processes, including signaling, polarization, adhesion, and membrane fusion. The yeast Saccharomyces cerevisiae is an ideal model system for examining the events of this critical and well-conserved process. Researchers employ yeast cells because they are rapidly growing, easy to manipulate, amenable to long-term storage, genetically tractable, readily transformed, and nonhazardous. The genetic and morphological characterizations of cell fusion in wild-type and fusion mutants have helped define the mechanism and temporal regulation required for efficient cell fusion. Ultrastructural studies, in particular, have contributed to the characterization of and revealed striking similarities within cell fusion events in higher organisms. This chapter details two yeast cell fusion ultrastructural methods. The first utilizes an ambient temperature chemical fixation, and the second employs a combination of high-pressure freezing and freeze substitution.

Structural characterization of the acid-degraded secondary cell wall polymer of Geobacillus stearothermophilus PV72/p2

The secondary cell wall polymer (SCWP) from Geobacillus stearothermophilus PV72/p2, which is involved in the anchoring of the surface-layer protein to the bacterial cell wall layer, is composed of 2-amino-2-deoxy- and 2-acetamido-2-deoxy-D-glucose, 2-acetamido-2-deoxy-D-mannose, and 2-acetamido-2-deoxy-D-mannuronic acid. The primary structure of the acid-degraded polysaccharide--liberated by HF-treatment from the cell wall--was determined by high-field NMR spectroscopy and mass spectrometry using N-acetylated and hydrolyzed polysaccharide derivatives as well as Smith-degradation. The polysaccharide was shown to consist of a tetrasaccharide repeating unit containing a pyruvic acid acetal at a side-chain 2-acetamido-2-deoxy-alpha-D-mannopyranosyl residue. Substoichiometric substitutions of the repeating unit were observed concerning the degree of N-acetylation of glucosamine residues and the presence of side-chain linked 2-acetamido-2-deoxy-beta-D-glucopyranosyl units: [Formula: see text].