[Antibodies against glyoxysomal membranes]

Antibodies against glyoxysomes were prepared by injection of purified glyoxysomal membranes from watermelon cotyledons (day 3) into rabbits and isolation of the gammaglobulin fraction from the antiserum by ammonium sulfate fractionation. Double gel diffusion as well as two-dimensional immunoelectrophoresis (tandem technique, Fig. 4) tests using the purified antiserum and glyoxysomes or crude cotyledon extracts gave a single converging immunoprecipitation band. The antigen concentrations at different developmental stages were determined by one-dimensional immunoelectrophoresis (Fig. 5). Cotyledons of dry seeds contain low but measurable amounts of antigen. After day 2 there is a fast increase and after day 3 a subsequent slow decline of antigen. Since mitochondria and endoplasmic reticulum also formed single identical bands with antiglyoxysoma antibodies (Fig. 6) the results of Fig. 5 reflect the synthesis and destruction of membrane material belonging to several organelles.The reported experiments support the hypothesis of Kagawa, Lord and Beevers (1973) that components of glyoxysomal and mitochondrial membranes originate in a light membrane fraction derived from the endoplasmic reticulum. The consequences of this hypothesis in terms of organelle morphogenesis are discussed.