a1 Tokyo Institute of Technology, Yokohama and Tokyo Metropolitian Insitute of Medical Science, Tokyo, Japan
M5 ganglioside (NeuGcα2–6Glcβl-' Cer) is the predominant glycosphingolipid in sea urchin eggs. Distribution of M5 ganglioside was studied in unfertilised and fertilised eggs of the sea urchin Hemicentrotus pulcherrimus by indirect immunofluorescence microscopy. In the cortices of unfertilised eggs, anti-M5 antibody strongly stained the submembranous, polygonal and tubular network of endoplasmic reticulum that was revealed by a membrane-staining dye, DiIC18(3). In addition to the cortical network of endoplasmic reticulum, at least two morphologically distinct vesicles were positive to the antibody. In the cortices isolated from fertilised eggs 30 min after insemination, the antibody stained only a similar network of endoplasmic reticulum, presumably the one reconstructed 5–10 min after fertilisation. During mitosis the endoplasmic reticulum is known to aggregate within the asters of the mitotic apparatus. Indeed, the antibody stained the asters and (more strongly) the vesicular components attaching to the periphery of the mitotic apparatus.
c1 Motonori Hoshi, Department of Life Science, Tokyo Institute of Technology, Nagatsuta, Midoriku, Yokohama 227, Japan. Fax: 81-45-923-0368.
1 Department of Life Science, Tokyo Institute of Technology, Yokohama, Japan
2 Department of Biomembrane Biochemistry. Tokyo Metropolitan Institute of Medical Science, Tokyo, Japan.
3 Gene Research Centre, Tokyo Institute of Technology, Tokyo, Japan.