Showing papers by "Takeshi Nakayama published in 2011"
TL;DR: It is proposed that Lepidodiniumplastids are of core chlorophyte origin, and 85 sequences newly determined in this study and recent progress in plastid genome sequencing enabled us to prepare an alignment comprised of 11Plastid proteins from green algal taxa that appropriately cover the diversity of Chlorophyta.
58 citations
TL;DR: A new kleptoplastidal dinoflagellate, Gymnodinium myriopyrenoides sp.
31 citations
TL;DR: Phylogenetic analyses considering these new sequences clearly indicate that the spheroid bodies were acquired by a common ancestor of rhopalodiacean diatoms and have been retained during host speciation.
Abstract: Members of the diatom family Rhopalodiaceae possess cyanobacteria-derived intracellular structures called spheroid bodies (SBs) that very likely carry out nitrogen fixation. Due to the shortage of molecular data from SBs and rhopalodiacean diatoms, it remains unclear how SBs were established and spread in rhopalodiacean diatoms. We here amplified the small subunit ribosomal DNA sequences from both host and SB in three rhopalodiacean diatom species, Epithemia turgida, E. sorex, and Rhopalodia gibba. Phylogenetic analyses considering these new sequences clearly indicate that the SBs were acquired by a common ancestor of rhopalodiacean diatoms and have been retained during host speciation.
31 citations
TL;DR: The ultrastructure and phylogenetic position of a free‐living heterotrophic flagellate, Tsukubamonas globosa, and detailed morphological comparisons elucidated that T. globosa possessed a novel set of morphological features, and could not be classified into any taxa in the Discoba clade.
Abstract: . We report the ultrastructure and phylogenetic position of a free-living heterotrophic flagellate, Tsukubamonas globosa n. gen., n. sp. This flagellate was isolated from a pond in the University of Tsukuba, Japan. Under light microscopy, the spherical vegetative cells were naked and highly vacuolated, and always swam with rotating motion. Electron microscopic observations revealed that T. globosa possessed a ventral feeding groove, which is one of the hallmark characteristics of the supergroup Excavata. The position of T. globosa was unresolved in the small subunit ribosomal RNA phylogeny. On the other hand, a multigene phylogeny using α-tubulin, β-tubulin, actin, heat shock protein 90, and translation elongation factor 2 robustly united T. globosa with members of the “Discoba” clade of Excavata, composed of jakobids, euglenozoans, and heteroloboseans, although the precise position of T. globosa in this clade remained unresolved. Our detailed morphological comparisons elucidated that T. globosa possessed a novel set of morphological features, and could not be classified into any taxa in the Discoba clade. Instead we classified T. globosa into Tsukubamonadidae n. fam. under Tsukubamonadida n. ord.
29 citations
TL;DR: A new species of Nephroselmis isolated from Japan, Fiji and South Africa is studied, providing some insights into the evolution of N. viridis, which possesses some ultrastructural characters shared with only the freshwater type species N. olivacea.
Abstract: The genus Nephroselmis (Nephroselmidophyceae), which had been placed in the Prasinophyceae, is one of the primitive green flagellates that are important to our understanding of the early evolution of green plants. We studied a new species of Nephroselmis isolated from Japan, Fiji and South Africa. This species has been known for a long time as undescribed species ‘N. viridis.’ N. viridis possesses some ultrastructural characters shared with only the freshwater type species N. olivacea, including a disc-like structure beneath the pyrenoid and bipolar spiny body scales with 1-5-8-5-1 spines. Molecular phylogenetic analysis based on 18S rDNA also supports a sister relationship between N. viridis and N. olivacea. However, N. viridis is distinguishable from N. olivacea by the shape of its starch sheath, its scales, its pigment composition and its habitat. In this paper, we designate the formal description of N. viridis sp. nov. We also describe variability in the 18S rDNA introns of various N. viridis strains. This detailed study of N. viridis provides some insights into the evolution of Nephroselmis.
17 citations