'Nectosome': a novel cytoplasmic vesicle containing nectin in the egg of the sea urchin, Temnopleurus hardwickii.
Localization of an extracellular matrix protein, Th-nectin, in the eggs and embryos of the sea urchin Temnopleurus hardwickii was examined by both immunofluorescence and immunoelectron microscopy. The protein is associated with a tubular structure packaged in rod-shaped vesicles that were designated as 'nectosomes'. In unfertilized eggs, nectosomes are distributed uniformly throughout the cytoplasm, but after fertilization, they gradually translocate to the cortical zone where they are arranged perpendicular to the plasma membrane. The migration of the nectosomes was strongly inhibited by cytochalasin B, which suggested that microfilaments play an important role in this process. Immunocytochemical and immunoblotting analyses both ascertained that nectin is secreted into the hyaline layer. Some nectosomes remain in the apical cytoplasm of dermal cells until the gastrula stage. Ultrastructural examination revealed that the accumulation of nectosomes in the oocyte cytoplasm begins quite early in oogenesis, concomitant with the accumulation of cortical vesicles.
Kato
Koichi H
KH
Department of Biology, Graduate School of Natural Sciences, Nagoya City University, Mizuho-ku, Nagoya 467-8501, Japan. kato@nsc.nagoya-cu.ac.jp
Abe
Tetsuya
T
Nakashima
Seiko
S
Matranga
Valeria
V
Zito
Francesca
F
Yokota
Yukio
Y
D000818:Animals; D022162:Cytoplasmic Vesicles / Q000737:chemistry* / Q000648:ultrastructure; D005089:Exocytosis; D016326:Extracellular Matrix Proteins; D005306:Fertilization; D006023:Glycoproteins / Q000032:analysis* / Q000648:ultrastructure; D037102:Lectins; D016253:Microscopy, Immunoelectron; D009866:Oogenesis; D012617:Sea Urchins / Q000737:chemistry / Q000166:cytology* / Q000648:ultrastructure
D016326:Extracellular Matrix Proteins; D006023:Glycoproteins; D037102:Lectins; C057966:echinonectin protein, Lytechinus variegatus