SIALYLATION PATTERNS OF THE MOUSE PAROTID SECRETORY GRANULES - COMBINED DEACETYLATION, ENZYMATIC DEGRADATION AND LECTIN-GOLD BINDING

We investigated the lectin cytochemistry of control and sialidase-dige sted sections of the mouse parotid gland by postembedding techniques. PNA and DBA lectins were used and their affinity sites were localized by employing conjugates with horseradish peroxidase that then reacted with anti-horseradish peroxidase antibody and protein A-gold. Potassiu m hydroxide pretreatment also was used before sialidase/PNA and DBA bi nding to investigate sialic acid acetylation. Ultrathin sections were obtained from specimens embedded in the acrylic hydrophilic resin, Bio acryl. The acini of mouse parotid gland contained polymorphous secreto ry grannies differentially stained by the two lectins; the use of sial idase digestion and KOH deacetylation revealed that the sialic acids l inked to beta-galactose are restricted to the electron-dense concentri c areas of target granules, whereas the sialic acids linked to alpha-N -acetylgalactosamine contain C-4-acetylated groups and are preferentia lly located in rite electron-lucent regions of bizonal granules.