Compartmentalization of secretory proteins in pancreatic zymogen granules as revealed by immunolabeling on cryo-fixed and molecular distillation processed tissue

• Published in: Biology of the cell Vol. 81; no. 2; pp. 153 - 163
• Main Authors: Gingras, Diane, Bendayan, Moïse
• Format: Journal Article
• Language: English
• Published: Oxford, UK Elsevier SAS 1994; Blackwell Publishing Ltd; Portland
• Subjects: amylase; Amylases - secretion; Analytical, structural and metabolic biochemistry; Animals; Biological and medical sciences; Cell Compartmentation; cryo-fixation; Cryopreservation; Cytoplasmic Granules - metabolism; Cytoplasmic Granules - ultrastructure; Fundamental and applied biological sciences. Psychology; General aspects, investigation methods; immunocytochemistry; Immunohistochemistry; Male; Microscopy, Electron; molecular distillation drying; pancreas; Pancreas - metabolism; Pancreas - ultrastructure; Plastic Embedding; Proteins; Rats; Rats, Sprague-Dawley; Tissue Fixation; cryo-fixation; immunocytochemistry; molecular distillation drying; amylase; pancreas; Compartmentalization; Gold; Amylase; Rat; Enzyme; Immunocytochemistry; Rodentia; Chemical labelling; Zymogen; Vertebrata; Mammalia; Antigenicity; Cryopreservation; Secretory protein; Secretion granule; Pancreas
• ISSN: 0248-4900; 1768-322X
• DOI: 10.1016/S0248-4900(94)80006-5

Immunogold labeling of amylase obtained over zymogen granules of rat pancreatic acinar cells processed through cryofixation, molecular distillation drying and embedding in resins was found to be of high intensity and displayed a particular pattern. Indeed, it was concentrated in certain areas of the granules leaving others devoid of gold particles. This pattern of labeling reflects a strong compartmentalization of the secretory proteins within each granule. In order to assess this phenomenon, we have compared the intensities and the pattern of distribution of the labelings in tissues processed through: chemical fixation with embedding in various resins, cryo-ultramicrotomy and cryo-fixation followed by molecular distillation drying. Serials sections and double labeling experiments were performed for further evaluation of the results and for assessing artefactual displacement of proteins during tissue preparation. The results obtained indicate that the secretory proteins are indeed segregated within the granule which appears thus as a well organized structure. Cryo-fixation combined with molecular distillation appears thus to be superior in terms of preservation of protein antigenicity and retention of cellular components close to their living state.