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Ultrastructural localization of highly variable 185/333 immune response proteins in the coelomocytes of the sea urchin, Heliocidaris erythrogramma
Author(s) -
Dheilly Nolwenn M,
Birch Debra,
Nair Sham V,
Raftos David A
Publication year - 2011
Publication title -
immunology and cell biology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.999
H-Index - 104
eISSN - 1440-1711
pISSN - 0818-9641
DOI - 10.1038/icb.2011.3
Subject(s) - microbiology and biotechnology , sea urchin , biology , phagocytosis , vesicle , population , ultrastructure , phagosome , golgi apparatus , chemistry , biochemistry , membrane , anatomy , demography , endoplasmic reticulum , sociology
The 185/333 proteins of sea urchins represent a family of highly variable immune response molecules with unknown functions. In this study, we show that 185/333 proteins are expressed by three cell types: amoebocytes, colourless spherule cells and gut‐associated amoebocytes. A sub‐population of amoebocytes express 185/333 proteins on the membranes of vesicles emanating from the trans‐Golgi and which later fuse with the plasma membranes of the cells. The previously uncharacterized gut‐associated amoebocytes also show a high level of 185/333 protein expression on their internal vesicles and plasma membranes. Colourless spherule cells contain 185/333 proteins within large spherules (specialized intracellular vesicles). In the presence of bacteria and yeast, the ultrastucture of colourless spherule cells changes and 185/333 proteins disappear. In contrast, 185/333 proteins were not found in the phagosomes of coelomocytes. The 185/333‐positive gut amoebocytes were often associated with anuclear bodies, which appeared to incorporate material of microbial origin that was surrounded by 185/333 proteins. The association between 185/333 proteins on gut amoebocytes and anuclear bodies suggests that these proteins may be involved in the phagocytosis of microbes in the gut epithelium.