Immunolocalization of centrin during fertilization and the first cell cycle in Fucus distichus and Pelvetia compressa (Fucales, Phaeophyceae)

Antibodies that recognize the centrosome-associated protein centrin were used to characterize centrosomal origin and positioning during fertilization and the first cell cycle in Fucus distichus subsp. evanescens (C. Agardh) Powell and Pelvetia compressa (J. Agardh) Be Tent. Centrin was identified in sperm, eggs, and zygotes on protein blots, indicating the protein is present in both gametes. Using immunofluorescence microscopy, centrin was found in discrete foci in sperm. In contrast, eggs lack centrosomes and centrin was not detectable by immunofluorescence, indicating that centrin was probably dispersed in the cytoplasm. Two foci of centrin were present on the nuclear envelope of zygotes, but microtubules remained dispersed over the zygotic nucleus. Centrin foci separated over the nuclear envelope as the first cell cycle progressed. Microtubules became concentrated at the centrin foci to form centrosomes that gave rise to the spindle poles at mitosis.