Fascinating attachment strategy of protococcidian Eleutheroschizon duboscqi
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| Year of publication | 2013 |
| Type | Conference abstract |
| MU Faculty or unit | |
| Citation | |
| Description | Apicomplexa represent very successful group of unicellular parasites that evolved unique adaptations for invading and surviving within their hosts. It is assumed that ancestral apicomplexans parasitized marine annelids, and their adaptation to the parasitic life style and further radiation took place before the era of vertebrates. First they spread to other marine invertebrates, then to freshwater and terrestrial invertebrates, and finally to vertebrates. Their zoite exhibits a high degree of polarity in that it has an apical pole equipped with a unique complex, comprising specialized secretory organelles, polar rings, and a conoid. This invasion apparatus traditionally used as the best defining feature for phylum Apicomplexa, can be also found in other Myzozoa - a group comprising apicomplexans, dinoflagellates, and several lineages of free-living predatory or parasitic flagellates that employ a myzocytosis-based mode of feeding. Apicomplexan evolution most likely progressed from myzocytotic predation to myzocytotic extracellular parasitism (e.g. gregarines, cryptosporidia), and finally to intracellular parasitism typical for coccidians. This study focuses on attachment strategy of protococcidian Eleutheroschizon duboscqi, a representative of marine deep-branching apicomplexans restricted to invertebrates, which shares features of both the gregarines and coccidians. Littoral samples of host polychaete Scoloplos (Scoloplos) armiger were collected at the Nikolai Pertsov White Sea Biological Station of MSU (Velikaya Salma, Kandalaksha). When attached to the host cell, parasite is covered by a parasitophorous sac resembling that of cryptosporidia, while its attachment site conspicuously resembles gregarine epimerite. The attachment apparatus consists of several short and thick projections arranged in circle, surrounded by another circle of filamentous fascicles. No organelles of apical complex were observed. |
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