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  • Sea urchin  (3)
  • 2010-2014
  • 1990-1994  (3)
  • 1
    ISSN: 1432-041X
    Keywords: Sea urchin ; Jelly coat ; Accessory cell ; Oogenesis ; Immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Summary The immunocytochemical localization of the egg-jelly macromolecule, a fucose sulphate glycoconjugate (FSG) that induces the acrosome reaction in spermatozoa, was investigated in ovaries of the sea urchin Hemicentrotus pulcherrimus by use of a polyclonal antibody. The polyclonal antibody reacted with the accessory cells and oocytes in the ovarian lumen. In the accessory cells, evidence of an intense immunohistochemical reaction was observed in many globules of variable density. Products of the specific immunohistochemical reaction were frequently observed in the surface region of oocytes, at a distance from the ovarian wall. At the ultrastructural level, the polyclonal antibody was found to react with the material present in the vacuole-like structures of the globules in the accessory cells. Many gold particles, demonstrating specific immunolabelling, were associated with well-developed microvilli on the vitellogenic oocytes. In the mature oocytes, intense labelling was observed in the jelly coat but not in the vitelline coat. By contrast, oogonia and early oocytes were barely labelled. Quantitative data indicated that the extent of immunolabellings in the surface region of oocytes was very high in the vitellogenic and mature oocytes. In all cases, neither the oocyte cytoplasm nor the subcellular organelles were labelled. These results suggest that FSG is produced by the accessory cells and is deposited initially on the surface of vitellogenic oocytes for the formation of jelly. These findings may provide a new insight into the role of the accessory cells in the reproductive process of the sea urchin.
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  • 2
    ISSN: 1432-041X
    Keywords: Sea urchin ; Sperm-activating peptide ; Accessory cell ; Oogenesis ; In situ hybridization
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract A cDNA clone encoding egg jelly peptide, SAP-I (Gly-Phe-Asp-Leu-Asn-Gly-Gly-Gly-Val-Gly), was isolated from a Hemicentrotus pulcherrimus ovary cDNA library and its nucleotide sequence was determined. The cDNA was 1282 by long and an open reading frame predicted a protein of 334 amino acids containing 5 SAP-I and 7 SAP-I-like decapeptides, each separated by a single lysine residue. The cDNA hybridized to two species of mRNA (1.3 kb and 2.0 kb) from H. pulcherrimus ovaries. Northern blot analysis showed that the 1.3 kb transcripts appeared in ovaries collected from November to April and the 2.0 kb transcripts were detected only in ovaries collected in January. An expression study of the SAM precursor gene, by in situ hybridization with a non-radioactive RNA probe synthesized using the 1.3 kb cDNA as template, demonstrated that abundant SAM precursor transcripts were expressed in the accessory cells, but not in the growing oocytes.
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  • 3
    ISSN: 1432-041X
    Keywords: Sea urchin ; Egg jelly ; Ovary ; Development ; Immunocytochemistry
    Source: Springer Online Journal Archives 1860-2000
    Topics: Biology
    Notes: Abstract In the sea urchin Hemicentrotus pulcherrimus, the egg-jelly macromolecule, a fucose sulphate glycoconjugate (FSG) that induces the acrosome reaction in spermatozoa, originates from the accessory cells in the ovary. In the present study we examined the seasonal variations in the distribution of FSG in the ovary by immunocytochemistry with a polyclonal antibody. An enzyme-linked immunosorbent assay indicated that FSG was present in supernatants of extracts of ovaries throughout the development of the ovary. However, the immunohistochemical study showed that there are marked seasonal changes in the distribution of FSG in ovaries. The polyclonal antibody reacted strongly with globules of accessory cells before the beginning of the breeding season (August to December). During the breeding season (February to April), the immunohistochemical reaction was found on the surface of oocytes but was weak in the accessory cells. At the ultrastructural level, the antibody reacted with globules of variable density in accessory cells. Intense immunolabelling was observed in the vacuole-like structures of the globules. Sometimes, products of the specific immunocytochemical reaction were found in the Golgi apparatus in these globules. Quantitative examination indicated that FSG was actively produced by the accessory cells from the late non-breeding season to the pre-breeding season. These results suggest that there are marked seasonal variations in the production of FSG by the accessory cells in the sea urchin ovary. These findings also provide new evidence that accessory cells exhibit dynamic changes during the reproductive process in the sea urchin.
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