PROPERTIES OF RICE (ORYZA-SATIVA L.) FECAL PROTEIN PARTICLES - LIGHT AND ELECTRON-MICROSCOPIC OBSERVATIONS

The indigestible remains of rice (Oryza sativa L.) found in faeces of monogastric animals (faecal protein particles) appear as isolated, ref ractive spheres 1-2 mu m in diameter. Still controversial, the prolami n-containing PB-I rice protein body has generally been proposed as the progenitor. We used polyclonal antibodies to purified fractions of ri ce prolamins and glutelins, to total rice protein, and to enzymaticall y-and chemically-derived waste particles of rice. Three classes of res idual particles were examined immunocytochemically using Protein A-gol d procedures to determine the polypeptide types present, and thus thei r possible origin. All particles contained antigenic determinants for all antibodies to the extracted rice polypeptides studied. There was a lso evidence of protein(s) peculiar to the residual bodies; the label on intact protein bodies showed a small amount of the unique protein(s ), but label increased for all residual particles studied. In contrast . antigenic determinants for total rice protein were much reduced in r esidual particles. While measurement of profiles of intact PB-I and fa ecal protein particles shows no significant difference between their d iameters, the immunocytochemical evidence linking faecal protein parti cles exclusively with PB-I rice protein bodies is less clear because i ntact PB-I and PB-II both show evidence of the unique protein also fou nd in the residual particles. (C) 1998 Academic Press Limited.