SSU rRNA reveals a sequential increase in shell complexity among the euglyphid testate amoebae (Rhizaria: Euglyphida)

The existing data on the molecular phylogeny of filose testate amoebae from order Euglyphida has revealed contradictions between traditional morphological classification and SSU rRNA phylogeny and, moreover, the position of several important genera remained unknown. We therefore carried out a study aiming to fill several important gaps and better understand the relationships among the main euglyphid testate amoebae and the evolutionary steps that led to the present diversity at a higher level. We obtained new SSU rRNA sequences from five genera and seven species. This new phylogeny obtained shows that (1) the clade formed by species of genera Assulina and Placocista branches unambiguously at the base of the subclade of Euglyphida comprising all members of the family Trinematidae and genus Euglypha, (2) family Trinematidae (Trachelocorythion, Trinema, and Corythion) branches as a sister group to genus Euglypha, (3) three newly sequenced Euglypha species (E. cf. ciliata, E. penardi, and E. compressa) form a new clade within the genus. Since our results show that Assulina and Placocista do not belong to the Euglyphidae (unless the Trinematidae are also included in this family), we propose the creation of a new family named Assulinidae. Consequently, we give a family status to the genera Euglypha and (tentatively) Scutiglypha, which become the new family Euglyphidae. The evolutionary pattern suggested by SSU rRNA phylogeny shows a clear tendency towards increasing morphological complexity of the shell characterised by changes in the symmetry (migration of the aperture to a ventral position and/or compression of the shell) and the appearance of specialised scales at the aperture (in families Trinematidae and Euglyphidae).     

Remodeling the Specificity of an Endosomal CORVET Tether Underlies Formation of Regulated Secretory Vesicles in the Ciliate Tetrahymena thermophila

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Inverted terminal repeat sequence in the macronuclear DNA of Stylonychia pustulata

The structure of macronuclear DNA of a hypotrichous ciliate, Stylonychia pustulata, was examined by both electron microscopy and nucleotide sequence analysis. The DNA in the macronucleus consists of small linear molecules with average length of about 3400 base pairs (bp). Most, if not all, of these DNA molecules have identical inverted terminal repeat sequence of 20 nucleotide residues. This sequence is 5'-CCCCAAAACCCC-AAAACCCC.     

Testate Amoebae in the 407-Million-Year-Old Rhynie Chert

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Parastrombidinopsis shimi n. gen., n. sp. (Ciliophora: Choreotrichia) from the coastal waters of Korea: morphology and small subunit ribosomal DNA sequence

The planktonic ciliate Parastrombidinopsis shimi n. gen., n. sp. is described from both living cells and quantitative protargol-stained (QPS) preparations and the sequence of the small subunit rDNA (SSU rDNA) is reported. This species is almost oval when the cells are alive; when stained, it is cylindrical for the upper two-fifths, half-bowl shaped for the middle two-fifths, and narrow rodshaped for the lower one-fifth. The ranges (and mean +/- standard deviation, n = 20) of cell length, cell width, and oral diameter of living cells were 112-221 microm (168 +/- 39), 88-176 microm (121 +/- 30), and 53-110 microm (80 +/- 14), respectively, while those of the QPS-stained specimens (n = 54) were 88-225 microm (162 +/- 29), 55-163 microm (102 +/- 19), and 53-98 microm (69 +/- 9), respectively. Thirty-six to 48 external oral polykinetids had cilia 25-40 microm long. However, unlike Strombidinopsis species sensu stricto, P. shimi has an external oral polykinetid zone that is an open circle. This species has two shorter polykinetids associated with the end of the oral polykinetid zone, deep in the oral cavity. Like Strombidinopsis species in the subclass Choreotrichia, 36-50 somatic kineties were equally spaced around the cell body and extended from the oral to the posterior regions with 68-105 dikinetids per kinety. Both kinetosomes of each kinetid bore cilia 3-10 microm long. Parastrombidinopsis shimi had 2 (1-4) ovoid macronuclei of 20-82 x 15-32 microm. When properly aligned, the sequence of the SSU rDNA of P. shimi (GenBank Accession No. AJ786648) was approximately 5% different from that of Strobilidium caudatum and 6% different from that of two Strombidinopsis species. Based both on morphology and gene sequence divergence, we establish this is as a new species in a new genus belonging to the family Strombidinopsidae.     

Plasmodium iophurae: cationized ferritin staining, an electron microscope cytochemical method for differentiating malarial parasite and host cell membranes

The surface membranes of erythrocyte-free Plasmodium lophurae and its host cell, the duckling erythrocyte, stain differentially when exposed to cationized ferritin (CF). At low CF concentrations (0.18 mg/ml) only the outer surface of the red cell stains, whereas at the standard concentration (0.7 mg/ml) both the red cell and the parasitophorous vacuolar membranes (PVM) were stained on their outer faces. By using a high CF concentration (3.7 mg/ml), the parasite's plasma membrane (PM) could be distinguished from that of the PVM: The former did not bind CF, whereas the latter was stained on its outer surface. At this level of CF the red cell membrane stained on both faces if these surfaces were exposed to stain. Although the PVM is formed by red cell endocytosis of the parasite, it can be distinguished from the membrane of the erythrocyte as well as that of the PM.     

Ultrastructure of spermiogenesis and spermatozoa of Gymnotus cf. anguillaris and Brachyhypopomus cf. pinnicaudatus (Teleostei: Gymnotiformes)

The ultrastructure of spermiogenic stages and spermatozoa of representatives of two gymnotiform families, Gymnotus cf. anguillaris (Gymnotidae) and Brachyhypopomus cf. pinnicaudatus (Hypopomidae) were studied. Spermiogenesis of both species is characterized by lateral development of the flagellum and formation of a nuclear fossa. Some differences were found between these species, such as whether (B. cf. pinnicaudatus) or not (G. cf. anguillaris) nuclear rotation occurs, permanence of the cytoplasmic channel, and type and localization of the nuclear fossa. In the G. cf. anguillaris spermatozoon the nucleus is spherical with highly condensed chromatin. The nuclear fossa is shallow and lateral and is associated with the centriolar complex through stabilizing fibrils. The midpiece is short, with many vesicles, a cytoplasmic channel, and elongate mitochondria. In the B. cf. pinnicaudatus spermatozoon the ovoid nucleus is elongated lateral and posterior to the centriolar complex, and has highly condensed chromatin. The eccentric nuclear fossa is of the moderate type, and contains the entire centriolar complex. The midpiece is long, with numerous vesicles, elongate mitochondria, and no cytoplasmic channel. In both species the flagella are laterally disposed in relation to the nucleus and comprise of the classical 9+2 axoneme. Most of the characteristics found in the spermatozoa of these two species of Gymnotiformes are shared with species of Characiformes, whereas only a few are also found in Siluriformes. This suggests that Gymnotiformes and Characiformes may be more closely related than previously proposed.