REISOLATION AND REDESCRIPTION OF PELOBIONT PELOMYXA PARADOXA PENARD, 1902
(ARCHAMOEBAE, PELOBIONTIDA)
L.V. Chistyakova,1,* M.A. Berdieva,1,3 A.O. Frolov,2 A.V. Goodkov 3
1 St. Petersburg State University, 2 Zoological Institute RAS and 3 Institute of Cytology RAS, St. Petersburg;
* e-mail: batsnwr@mail.ru
Morphology of a pelobiont Pelomyxa paradoxa Penard, 1902 was investigated at light- and electron-microscopical
levels. Locomoting cells are cigar-shaped. The cells produce many hyaline pseudopodia of digital
and conical form at lateral sides of the body. The organism has a pronounced hyaline bulbous uroid with broad
peripheral zone of hyaloplasm and many conical hyaline villi. There is a thin layer of amorphous glycocalix at
the cell surface. «Structure» and food vacuoles of different size are very abundant in the endoplasm. Two different
species of prokaryote endocytobionts are peculiar for P. paradoxa. Uninucleate stage dominates in the life
cycle of P. paradoxa. Usually there are no more than 10—12 nuclei in multinucleate forms of P. paradoxa. Pelomyxae
nuclei are closely surrounded by thick multilaminar layer and additionally by one more layer, which is
formed by small vesicles with electron-dense content. Several irregular-shaped nucleoli are situated at the nucleus
periphery. Inside the nucleoli, and sometimes directly in nucleoplasm the small round bodies are revealed,
these bodies being formed by tightly packed electron-dense fibrils. Many non-motile flagellae are located mainly
in the uroidal zone of the cell. Pronounced lateral root and 50—60 radial microtubules originate from the
electrone-dense muft around the kinetosome. All elements of the rootlet system of flagella are limited by peripheral
layers of cytoplasm. P. paradoxa occupy an intermediate position between two groups of species of Pelomyxa
genus — P. gruberi + P. prima and P. palustris + P. stagnalis + P. belewski, which differ greatly by the
organization of their flagella basal apparatus.
Key words: Archamoebae, Pelomyxa, morphology, ultrastructure
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