A comparison of the structure and function of nematocysts in free-living and parasitic cnidarians (Myxozoa).

A comparison of the structure and function of nematocysts in free-living and parasitic cnidarians (Myxozoa). Int J Parasitol. 2020 Jul 21;: Authors: Americus B, Lotan T, Bartholomew JL, Atkinson SD Abstract Myxozoans are obligate parasites that have complex life cycles requiring alternate vertebrate and invertebrate hosts, with transmission via microscopic waterborne spores. Unusually for parasites, they belong to the phylum Cnidaria, alongside thousands of free-living corals, sea anemones, jellyfish and hydrozoans. Their cnidarian affinity is affirmed by genetic relatedness and the presence of nematocysts, historically called "polar capsules" in myxozoan research. Free-living cnidarians utilize this cellular weaponry for defense, predation and adhesion, whereas myxozoans use it to anchor to their hosts as the first step in infection. Despite the ∼650 million years of divergence between free-living cnidarians and myxozoans, their nematocysts retain many shared morphological and molecular characters. Both are intra-cellular capsules with a single opening, and contain a coiled, evertable tubule. They are composed of unique nematocyst proteins, nematogalectin and minicollagen, and both likely contain an internal matrix of metal cations covalently bound to the anionic polymer poly-gamma glutamate. The rapid dissociation of this matrix and the resulting increase in internal osmotic potential is the driving force behind tubule elongation...
Source: International Journal for Parasitology - Category: Parasitology Authors: Tags: Int J Parasitol Source Type: research