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Flagellar Root (flagellar + root)
Selected AbstractsARE CYTOPLASMIC POCKETS (MTR/POCKET) PRESENT IN ALL PHOTOSYNTHETIC EUGLENOID GENERA?1JOURNAL OF PHYCOLOGY, Issue 4 2002Woongghi Shin In 1985, the existence of a cytoplasmic pocket formed from the reservoir membrane in the photosynthetic euglenoid Colacium was described. A band of reinforcing microtubules (MTR) derived from the ventral flagellar root lined the pocket, and a dense fibrillar mesh was associated with the membrane. A comparison of bodonid cytostomes, colorless euglenoid cytostomes, and the reservoir pocket found in Colacium suggested that the three structures were homologous and that photosynthetic euglenoids arose from phagotrophic ancestors. MTR/pockets have since been reported in other photosynthetic euglenoids, including Euglena, Eutreptia, Eutreptiella, Cryptoglena, Tetreutreptia, and Phacus. We found MTR/pockets in three additional taxa, Lepocinclis, Trachelomonas, and Strombomonas, thereby demonstrating the presence of this complex in representatives of all the major photosynthetic genera. A comparison of the MTR/pocket complex across genera indicated a reduction in structural complexity that was consistent with recent phylogenetic schemes based on molecular characters. Three alternative hypotheses of the origin of MTR/pockets in phototrophic euglenoids are presented and discussed. [source] Ultrastructure and large subunit rDNA sequences of Lepidodinium viride reveal a close relationship to Lepidodinium chlorophorum comb. nov. (=Gymnodinium chlorophorum)PHYCOLOGICAL RESEARCH, Issue 1 2007Gert Hansen SUMMARY The ultrastructure of the green dinoflagellate Lepididodinium viride M. M. Watanabe, S. Suda, I. Inouye Sawaguchi et Chihara was studied in detail. The nuclear envelope possessed numerous chambers each furnished with a nuclear pore, a similar arrangement to that found in other gymnodinioids. The flagellar apparatus was essentially identical to Gymnodinium chlorophorum Elbrächter et Schnepf, a species also containing chloroplasts of chlorophyte origin. Of particular interest was the connection of the flagellar apparatus to the nuclear envelope by means of both a fiber and a microtubular extension of the R3 flagellar root. This feature has not been found in other dinoflagellates and suggests a close relationship between these two species. This was confirmed by phylogenetic analysis based on partial sequences of the large subunit (LSU) rDNA gene of L. viride, G. chlorophorum and 16 other unarmoured dinoflagellates, including both the ,type' culture and a new Tasmanian isolate of G. chlorophorum. These two isolates had identical sequences and differed from L. viride by only 3.75% of their partial LSU sequences, considerably less than the difference between other Gymnodinium species. Therefore, based on ultrastructure, pigments and partial LSU rDNA sequences, the genus Lepidodinium was emended to encompass L. chlorophorum comb. nov. [source] ULTRASTRUCTURAL STUDIES ON BIGELOWIELLA NATANS, GEN.JOURNAL OF PHYCOLOGY, Issue 4 2001ET SP. Three isolates from the Provasoli-Guillard National Center for Culture of Marine Phytoplankton at Bigelow Laboratory, previously labeled Pedinomonas sp. and Pedinomonas minutissima from the green algal class Pedinophyceae, have been examined by light microscopy and TEM and shown to belong to the Chlorarachniophyceae, a class of nucleomorph-containing amebae. The three isolates represent the first chlorarachniophycean flagellates to be discovered. The ultrastructure of the cells has been examined in detail, with particular emphasis on the flagellar apparatus, a feature not examined in detail in chlorarachniophytes before. Cells are basically biflagellate, but the second flagellum is represented by a very short basal body only. Flagellar replication has shown this flagellum to be the mature stage, that is, the no. 1 flagellum, whereas the long emergent flagellum is the no. 2 flagellum that shortens into a short basal body during cell division. Mitosis is open with a pair of centrioles at each pole. Emergent flagella are absent during mitosis. Cells may form cysts, and the flagellar basal bodies and part of the flagellar roots are maintained in the cysts. Four microtubular roots emanate from the basal bodies, and the path of one of them is very unusual and very unlike any other known flagellate. No striated roots were observed. Other fine-structural features of the cell include a very unusual type of pyrenoid and a special type of extrusome. Cells are mixotrophic. The three isolates are very similar and are described as Bigelowiella natans, gen. et sp. nov. Ultrastructurally, chlorarachniophytes do not show close relationship to any known group of algae or other protists. [source] Ultrastructural Description of Breviata anathema, N. Gen., N. Sp., the Organism Previously Studied as "Mastigamoeba invertens"THE JOURNAL OF EUKARYOTIC MICROBIOLOGY, Issue 2 2006GISELLE WALKER ABSTRACT. An understanding of large-scale eukaryotic evolution is beginning to crystallise, as molecular and morphological data demonstrate that eukaryotes fall into six major groups. However, there are several taxa of which the affinities are yet to be resolved, and for which there are only either molecular or morphological data. One of these is the amoeboid flagellate Mastigamoeba invertens. This organism was originally misidentified and studied as a pelobiont using molecular data. We present its first light microscopical and ultrastructural characterisation. We demonstrate that it does not show affinities to the amoebozoan pelobionts, because unlike the pelobionts, it has a double basal body and two flagellar roots, a classical Golgi stack, and a large branching double membrane-bound organelle. Phylogenetic analyses of small subunit ribosomal RNA suggest an affinity with the apusomonads, when a covariotide correction for rate heterogeneity is used. We suggest that previous molecular results have been subject to artefacts from an insufficient correction for rate heterogeneity. We propose a new name for the taxon, Breviata anathema; and the unranked, apomorphy-based name "Breviates" for Breviata and its close relatives. [source] | ||||||||||