Topic
Extrusome
About: Extrusome is a research topic. Over the lifetime, 19 publications have been published within this topic receiving 635 citations.
Papers
TL;DR: The hypothesis that trichocysts in Paramecium function as defensive organelles against predators is strongly supported and the hypothesis that the offense-defense interaction between Dileptus and Pramecium is mediated by their extrusomes is supported.
Abstract: A putative defensive function of trichocysts in Paramecium has been tested experimentally. Cells of trichocyst-non-discharge (tnd) mutant, artificially induced trichocyst-deficient cells, and intact wild-type cells were compared as prey for a carnivorous ciliate, Dileptus margaritifer. Cells of tnd mutants were eaten 9–45 times faster than wild-type cells by the predator in P. caudatum and P. tetraurelia. Encounters between paramecia and dilepti occurred in nearly the same frequency in mutant and wild-type cells. Paramecia with reduced numbers of trichocysts were obtained in P. caudatum, P. jenningsi, and P. tetraurelia by treating wild-type cells with lysozyme, an inducer of trichocyst discharge. These cells were eaten faster than intact cells by the predator and the rate of predation was inversely correlated with the remained capacity of trichocyst discharge. It was concluded that the discharge of trichocysts defends these species of Paramecium against D. margaritifer. Therefore, the results of this work strongly support the hypothesis that trichocysts in Paramecium function as defensive organelles against predators. The results also support the hypothesis that the offense-defense interaction between Dileptus and Pramecium is mediated by their extrusomes (toxicysts and trichocysts) and suggest that extrusomes in ciliates function as organelles for interspecific cell-cell interaction.
105 citations
TL;DR: The diversity of traits in dinoflagellate nematocysts demonstrates a stepwise route by which simple secretory structures diversified to yield elaborate subcellular weaponry.
Abstract: We examine the origin of harpoon-like secretory organelles (nematocysts) in dinoflagellate protists. These ballistic organelles have been hypothesized to be homologous to similarly complex structures in animals (cnidarians); but we show, using structural, functional, and phylogenomic data, that nematocysts evolved independently in both lineages. We also recorded the first high-resolution videos of nematocyst discharge in dinoflagellates. Unexpectedly, our data suggest that different types of dinoflagellate nematocysts use two fundamentally different types of ballistic mechanisms: one type relies on a single pressurized capsule for propulsion, whereas the other type launches 11 to 15 projectiles from an arrangement similar to a Gatling gun. Despite their radical structural differences, these nematocysts share a single origin within dinoflagellates and both potentially use a contraction-based mechanism to generate ballistic force. The diversity of traits in dinoflagellate nematocysts demonstrates a stepwise route by which simple secretory structures diversified to yield elaborate subcellular weaponry.
42 citations
TL;DR: The morphology, infraciliature, and extrusomes of Remanella multinucleata were studied in live cells, in protargol impregnated specimens, and with the scanning electron microscope, and suggest that they emerged from a common ancestor which looked similar to a present day Loxodes.
24 citations
TL;DR: Analysis of how these defects lead to altered trichocyst shape supports the notion that the protein processing is essential for morphogenesis, and indicates that (at least) two distinct processing reactions are probably involved in the maturation of these proteins.
22 citations
TL;DR: A study was undertaken on two marine Strombidium species by ultrastructural and cytochemical analysis as well as in vivo experiments to demonstrate their true nature, and negative staining indicated that these structures were transformed trichites.
Abstract: The trichites of Strombidium and related genera have been considered either as a cytoskeletal armature or as extrusomes. To demonstrate their true nature, a study was undertaken on two marine Strombidium species by ultrastructural and cytochemical analysis as well as in vivo experiments. Trichites, extending from the cortex into the cell, are rod-shaped, membrane-bounded, and have a complex structure. The following elements of the trichites, are distinguishable: an electron-transparent lumen, a laminated layer, and a compact layer. In trichites of one species, thin ''rings'' surround the lumen. Numerous short, curved tubules with a polysaccharide wall are present in the cytoplasm surrounding the trichites. At the cortical end, each trichite is enveloped by a ''cap'' of electron-dense proteinaceous material. In some cases, the cortical alveoli appear interrupted, forming a ''hole'' for trichite ejection. Ejection of rod- shaped structures, up to 5 times longer than resting trichites, was obtained by in vivo treatments with dextran and aminoethyldextran. Negative staining indicated that these structures were transformed trichites. As no other possible extrusive structures were observed in the cytoplasm of Strombidium, trichites were considered extrusomes.
17 citations
Related Topics (5)
Performance Metrics
| Year | Papers |
|---|---|
| 2017 | 2 |
| 2014 | 1 |
| 2013 | 1 |
| 2012 | 1 |
| 2011 | 1 |
| 2003 | 2 |