PROFILIN REVEALED IN POLLEN NUCLEI - IMMUNOELECTRON MICROSCOPY OF HIGH-PRESSURE FROZEN LEDEBOURIA-SOCIALIS ROTH (HYACINTHACEAE)

Cryoimmobilization by high-pressure freezing, combined with cryosubsti tution and resin embedding, allowed accurate retention in situ of the small (12-15 kDa) water-soluble protein, profilin, in anthers of Ledeb ouria socialis Roth (Hyacinthaceae). The subcellular distribution of p rofilin was investigated by using post-embedding immunogold labelling with rabbit antisera raised against recombinant birch profilin (RP) or birch COOH-terminal profilin peptide (RP3). The patterns observed in mature pollen grains are novel to eukaryotic organisms: profilin was c onsistently demonstrated within both the vegetative and generative nuc lei, an addition to its well-known presence in the cytoplasm. Methodol ogical and immunological aspects, as well as possible biological impli cations, of this finding are considered.