Hydra nematocysts in the flatworm Microstomum lineare: in search for alterations preceding their disappearance from the new host
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Nematocysts are characteristic organelles of the phylum Cnidaria. The free-living Platyhelminth Microstomum lineare preys on Hydra oligactis and sequesters nematocysts. All nematocyst types become phagocytosed without adherent cytoplasm by intestinal cnidophagocytes. Desmoneme and isorhiza nematocysts disappear within 2 days after ingestion whereas cnidophagocytes containing the venom-loaded stenotele nematocysts migrate out of the intestinal epithelia through the parenchyma to the epidermis. Epidermally localized stenoteles are still able to discharge suggesting that this hydra organelle does preserve its physiological properties. Three to four weeks after ingestion, the majority of stenoteles disappear from M. lineare. To search for alterations of nematocysts that might precede their disappearance, flatworms were stained with acridine orange, a dye that binds to poly-γ-glutamic acid present in hydra nematocysts. The staining properties of all three nematocyst types were indistinguishable during the first 60 min after ingestion of hydra tissue whereas 15 h later, the majority of desmoneme and isorhiza had lost their stainability in striking contrast to stenoteles. In M. lineare inspected 2, 4 and 10 days after feeding, 20–40% of stenoteles had lost their stainability with acridine orange. Non-stained stenoteles had sizes similar to their stained counterparts but some of them were slightly deformed. The presented data indicate that acridine orange staining allows the detection of early alterations of all three ingested nematocyst types preceding their disappearance from M. lineare. Furthermore, they support the notion that the transport of venom-loaded stenoteles to the epidermis provides a strategy of excretion.
KeywordsNematocyst Kleptocnidae Hydra Microstomum lineare Acridine orange
I am grateful to my former students Melanie Stiegler and Melanie Bunz who performed some preliminary experiments under my supervision. I am very grateful to Ulrich Scheer and Christian Stigloher for critically reading the manuscript.
Compliance with ethical standards
Conflict of interest
The author declares that there are no conflicts of interest.
All applicable national and institutional guidelines for the care and use of animals were followed.
- Beckmann A, Xiao S, Müller JP, Mercadante D, Nüchter T, Kröger N, Langhojer F, Petrich W, Holstein TW, Benoit M, Gräter F, Özbek S (2015) A fast recoiling silk-like elastomer facilitates nanosecond nematocyst discharge. BMC Biol 13:3. https://doi.org/10.1186/s12915-014-0113-1 CrossRefPubMedPubMedCentralGoogle Scholar
- Bode HR (1996) The interstital cell lineage of hydra: a stem cell system that arose early in evolution. J. Cell Sci 109:1155–1164Google Scholar
- Carré C, Carré D (1980) Les cnidocystes du cténophore Euchlora rubra (Kölliker 1853). Cah Biol Mar 21:221–226Google Scholar
- Conklin EJ, Mariscal RN (1977) Feeding behavior, ceras structure, and nematocyst storage in the Aeolid nudibranch, Spurilla neapolitana (Mollusca). Bull Mar Sci 27:658–667Google Scholar
- Goodheart JA, Bleidißel S, Schillo D, Strong EE, Ayres DL, Preisfeld A, Collins AG, Cummings MP, Wägele H (2018) Comparative morphology and evolution of the cnidosac in Cladobranchia (Gastropoda: Heterobranchia: Nudibranchia). Front Zool DOI. https://doi.org/10.1186/s12983-018-0289-2
- Grosvenor GH (1903) On the nematocysts of aeolids. Proc R Soc Lond 72:462–486Google Scholar
- Karling TG (1966) On nematocysts and similar structures in turbellarians. Acta Zool Fenn 116:3–28Google Scholar
- Martin CH (1908) The nematocyst of Turbellaria. Quart J Microsc Sci 52:261–277Google Scholar
- Ruppert EE, Barnes RD (1994) Invertebrate zoology, sixth edn. Saunders, New YorkGoogle Scholar
- von Siebold CT (1848) Lehrbuch der vergleichenden Anatomie der wirbellosen Thiere. Veith & Comp, Berlin, pp 161–163Google Scholar