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Feeding in a calcareous sponge: particle uptake by pseudopodia
Sally P Leys1, Dafne I Eerkes-Medrano
1Department of Biological Sciences, University of Alberta, Edmonton, Alberta, Canada, T6G 2E9. sleys@ualberta.ca
The Biological Bulletin
|October 26, 2006
Summary
Sponge filter feeding may not solely rely on specialized collar cells. Particle uptake in syconoid sponges involves phagocytosis by cell extensions, suggesting a less strict sieving function.
Area of Science:
- Marine Biology
- Cell Biology
- Zoology
Background:
- Sponges, as filter feeders, share similarities with choanoflagellates.
- Choanocytes, specialized cells in sponges, possess unique microvilli collars.
- The mechanism of particle transport to the cell surface by choanocytes remains unclear.
Purpose of the Study:
- To investigate particle interactions with choanocytes in syconoid sponges.
- To elucidate the process of particle uptake by sponge feeding cells.
Main Methods:
- Studied interactions between choanocytes and introduced latex microspheres and bacteria.
- Observed particle uptake in the feeding chambers of a syconoid calcareous sponge.
Main Results:
- 0.1-microm latex microspheres adhered to microvilli and choanocyte surfaces.
- Larger particles (0.5- and 1.0-microm beads, bacteria) were phagocytosed by lamellipodia and pseudopodial extensions.
- Choanocyte apical surface extensions, up to 16 microm, were observed, with most around 4 microm.
Conclusions:
- Particle uptake in syconoid sponges is less dependent on the strict sieving function of collar microvilli.
- Phagocytosis by lamellipodia and pseudopodial extensions plays a significant role in particle capture.
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