Mature Cereal Grain Endosperm: Rapid Glass Knife Sectioning for Examination of Proteins

Abstract

A simple, rapid procedure was developed by which the quality of endosperm protein in cereal grains could be evaluated by microscopic observation of the subcellular protein structure. Kernels with vitreous endosperm were sectioned without pretreatment at 3-4 μ with a glass knife. Floury endosperm tissues were fixed in 10% glutaraldehyde, pH 7.4, for 16 hr at 5 C, and boiled to gelatinize the starch. After drying, this tissue was sectioned as for vitreous endosperm. Sections were mounted on gelatin-coated slides and destarched with a-amylase. To identify sites of prolamine, alcohol-soluble protein was extracted for 1 hr at about 70 C with 80% ethanol. The subcellular proteins were stained with either iodine vapor or various organic dyes. Proteins were differentiated by a combination of staining and mounting in selected high refractive index liquids.