Protistology 3 (1) 15–29 (2003) A comparative study of zoospore cytoskeleton in Symphytocarpus impexus, Arcyria cinerea and Lycogala epidendrum
(Eumycetozoa)
Serguei A. Karpov 1, Yuri K. Novozhilov 2 and Ludmila V. Chistiakova 3
1 Biological and Soil Science Faculty of St. Petersburg State University, St. Petersburg, Russia
Summary
The ultrastructure of zoospores of the myxogastrids Symphytocarpus impexus B. Ing et
Nann.-Bremek. (Stemoniida), Arcyria cinerea (Bull.) Pers. (Trichiida), and Lycogala
epidendrum (L.) Fr. (Liceida) is reported for the first time, with special reference to
flagellar apparatus. The cytoskeleton in all three species includes microtubular and
fibrillar rootlets arising from both basal bodies of the flagellar apparatus. There is a
similarity in the presence and position of the rootlets N1-5 between our species and
other studied species of myxogastrids and protostelids. Thus, general conservatism of
cytoskeletal characters and homology among eumycetozoa have been confirmed for
these taxa. At the same time there is variation in the details of flagellar rootlets’ structure
in different orders and genera. The differences concern the shape of short striated fibre
(SSF) which is an organizing structure for microtubular rootlets r2, r3 and r4. Its
upper strand is more prominent in L. epidendrum. The fibrillar part of rootlet 1 is
connected to basal body 1 in S. impexus, to basal body 2 in A. cinerea, and to both basal
bodies in L. epidendrum. The rootlets r4 and r5 are very conservative and consist,
correspondigly, of 7 and 2 microtubules in all three species. The comparative analysis
of all investigated mycetozoan zoospores and Hyperamoeba is presented. Variations of
flagellar apparatus structure are ascribed not only taxonomic but also phylogenetic
value. Key words: Eumycetozoa, myxogastrids, protostelids, zoospore, phylogeny,
Symphytocarpus impexus, Arcyria cinerea, Lycogala epidendrum, Hyperamoeba,
comparative ultrastructure
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