Figure 1.
Drawings of Colponema vientamica (a–e) and Acavomonas peruviana (f–i):
(a, c) general view, short ventral groove, large food and contractile vacuoles; b) bean-shaped cell, nucleus, large food vacuole; d) ovoid cell with wide ventral groove; e) feeding of a starved cell with small anterior rostrum; (f, g, i) general view, large food vacuole and nucleus; h) feeding on the prey. a.f – anterior flagellum, c.v – contractile vacuole, f.v – food vacuole, gr – longitudinal groove, n – nucleus, p.f – posterior flagellum, pr – prey. Scale: 10 µm for all figures.
Figure 2.
Light micrographs of Colponema vientamica.
c.v – contractile vacuole, p.f – posterior flagellum, f.v – food vacuole. Scales: 10 µm for all figures.
Figure 3.
Light micrographs of Acavomonas peruviana.
c.v – contractile vacuole, a.f – anterior flagellum, p.f – posterior flagellum, f.v – food vacuole. Scales: 10 µm for all figures.
Figure 4.
Ultrastructure of Colponema vietnamica.
a) Electron micrograph of the cell. Anterior and posterior flagella (af and pf) end with narrowing tips – acronemes (an). The arrows point to the short fold of proximal part of the pf. b) The transversal section at the level of the nucleus (n). In some places the cell contains the alveoli (al) beneath the plasmalemma. Small cytosolic vesicles contain the rudiments of the mastigonemes (mn). Golgi apparatus (Ga) is situated close to the nucleus. Discharged toxicysts (tc) are found outside of the cell. The band of 5+1 microbules (bm) accompanies the pf. Food vacuole (fv) contains remnants of a prey cell. The neighboring cell (nc) is seen. c) The cross section of the pf. The thin fold (fl) is visible. d) Flagella are arranged mutually at an angle of 45 degrees. Right and left bands of microtubules (rbm and lbm) and fibrous band (fb) emerge from the bases of the pf which runs inside the short ventral groove (vg). The secondary microtubules (sm) run near af. The axosoma (as) is visible above the transverse plate (tp). e) The pf inside vg. sm originate from the microtubular band (bm). The conspicuous as is located above the transverse plate (tp) of the flagellum. Mastigonemes (mn) cover the pf. f) The short amorphous rhizoplast (rp) extends from the kinetosome of the posterior flagellum (kpf) towards the nucleus (n). G. Kinetosome area. Three microtubules (rbm) and fibrous bands (fb) lie close to the kpf. vg is armored by the left band of microtubules (lbm). Kinetosome of anterior flagellum (kaf) contains an axosome (as). Single secondary microtubules (sm) are seen. h) pf passes in the vg and bears thin mastigonemes (mn). as is visible in the transitional zone of the flagellum. Scales: 0.5 µm in (c–h); 1 µm in b); 5 µm in a).
Figure 5.
Cell organelles of Colponema vietnamica.
a) The appearance of secondary microtubules (sm) from the band of microtubules (bm) going near the proximal end of the kinetosome of the flagellum. Mastigonemes (mn) are included inside the vesicles. Axosome (as) of the flagellum resembles a muff. (b, c) The arrangement of the right band of microtubules (rbm) and left band of microtubules (lbm) lying parallel to the posterior flagellum (pf). The single secondary microtubule (sm) is visible. The band of the microtubules surrounds the kinetosome of posterior flagellum (kpf). d) The nucleus (n) contains a conspicuous compact nucleolus. The extensions of the perinuclear space have mastigonemes (mn). Golgi apparatus (Ga) lies close to the nucleus. e) The mitochondria (mt) contain tubular cristae in cross section. Mastigonemes (mn) are formed inside the perinuclear space. f) Osmiophilis granules represent storage compounds (rs). (g, h, i) The structure of the toxicysts. The longitudinal and transversal sections of mature toxicysts g) and h), empty discharged toxicyst i). Scales: 0.5 µm in (a–c), (h–i); 1 µm in d), e), f).
Figure 6.
The phylogenetic position of Colponema and Acavomonas species (in bold).
RAxML phylogenies of eukaryotes based on the 18S rDNA dataset (a), and the 18S+28S rDNA dataset (b). RAxML rapid bootstrap, PhyML aLRT and MrBayes posterior probability branch supports are shown at branches (>50/>0.8/>0.9 are shown as significant; dashes indicate insignificant support). Black dots indicate complete support (100/1/1). Numbers of sequences in collapsed clades are shown in brackets.
Table 1.
Comparative morphology of considered organisms.
Figure 7.
(a–d) Colponema edaphicum (from Mylnikov and Tikhonenkov [43]), (e–i) C. marisrubri (from Mylnikov and Tikhonenkov [25]), (j–m) C. loxodes ((j, k) from Zhukov and Mylnikov [41]; l) from Chadefaud [42]; m) from Lemmermann [38], n) C. symmetricum (from Sandon [39]), o) C. globosum (from De Faria et al. [51]). a.f – anterior flagellum, f.v – food vacuole, gr – longitudinal groove, n – nucleus, p.f – posterior flagellum. Scales: (a–c), (e–i) –10 µm; d) –1; (j–m) –20 µm; (n, o) –15 µm.
Figure 8.
Light and electron micrographs of colponemids.
(a–f) Colponema edaphicum: a) large food vacuole is visible, b) cell division, (c, d) two heterodymanic flagella and (e, f) extrusive organelle toxicyst (TEM), ((a–c), f) from Tikhonenkov et al. [64], (d, e) from Mylnikov et al. [65]; g) Colponema marisrubri (from Mylnikov and Tikhonenkov [25]). a.f – anterior flagellum, f.v – food vacuole, p.f – posterior flagellum, c.v – contractile vacuole, ac – acronema, tc – toxicyst. Scales: (a–e), g) –10 µm; f) –1 µm.
Table 2.
Classification of alveolates.