The crystal lattice of the pyrenoid matrix of Prorocentrum Micans (original) (raw)
Related papers
Phycologia, 2007
We have reexamined the original culture of Prorocentrum arabianum Morton et Faust (CCMP 1724) using a combination of light and electron microscopy in addition to gene sequence data. Compared to the original description of P. arabianum (Morton et al. 2002), the new observations revealed it to possess two pyrenoids surrounded by starch sheaths and two types of valve pores, but marginal pores were absent. Cells kept in culture for nearly a decade now appeared symmetrical to asymmetrical in outline rather than asymmetrical as in the original description. In culture, P. arabianum attached to the bottom of culture flasks instead of being an active swimmer. Also in culture it produced large amounts of mucus. Studying serial sectioned cells in the transmission electron microscope, the periflagellar area was seen to comprise nine platelets. The overall arrangement of platelets agreed with Taylor's scheme from 1980 except for one additional plate labeled a2 situated between a1, b and e. Further ultrastructural examination of P. arabianum revealed for the first time a connection between a pusule-like organelle surrounded by two membranes and the accessory pore within the periflagellar area. We speculate that the pusule canal is used for discharging mucus or particulate matter through the accessory pore. The LSU rDNA sequence divergence between P. arabianum and P. concavum isolated from Malaysia was only 0.2%. As such a low divergence value is usually seen only at the population level, we also determined nuclear-encoded ITS 1 and ITS 2 and the cytochrome b (cob) gene residing in the mitochondrial genome in the two taxa. These DNA fragments were identical (ITS 1 and ITS 2) or almost identical (cytochrome b) when comparing P. arabianum and P. concavum. Amalgamating all available information from ultrastructure and molecular data, we conclude that P. arabianum is a synonym of P. concavum. It should, however, be noted that there is a difference in toxin profile between the two isolates. A phylogeny based on partial LSU rDNA including 14 species of Prorocentrum and 40 other dinoflagellates indicated that the genus may comprise six groups, and each of these are supported by a combination of morphological features and toxin production. As statistical support from bootstrap values or posterior probabilities for the divergent branches in the LSU tree was low, we refrain from major systematic changes of the genus Prorocentrum until more species are examined in the electron microscope and new DNA fragments other than ribosomal genes become available.
Ultrastructure and ontogeny of a new type of eyespot in dinoflagellates
Protoplasma, 1994
Ultrastructure and ontogeny of a new type of eyespot in dinoflagellates is described. A marine tidal poolGymnodinium natalense is found to possess a highly organized eyespot whose structure is unique among dinoflagellates. The eyespot is rectangular in ventral view, C-shaped in apical view, and is located posterior to the sulcus. The eyespot is independent of the chloroplast and consists of several (typically six) layers of hemi-cylindrical walls which are concentrically arranged with narrow spacing between them. Each hemicylindrical wall is enclosed by a single unit membrane and is composed of many regularly arranged rectangular crystalline bricks. These crystalline bricks are produced in small vesicles which are formed in the invaginations of the chloroplast. The vesicles containing newly formed crystalline bricks are then transported to the sulcal area to assemble the eyespot. The crystalline bricks are arranged in a neat row within the vesicle termed “eyespot forming vesicle” (EFV), which is located near the sulcus. The hemi-cylindrical wall is constructed within the EFV. Based on the structure of the eyespot, viz. consisting of concentric multi-layered walls, the eyespot is thought to act as a quarter-wave stack antenna.
Light and electron microscopical observations on Protoceratium reficulatum (Dinophyceae)
The coldwater dinoflagellate Peridiniella catenata has been examined by light and electron microscopy. The fine-structure resembles that of other dinoflagellates with regard to the dinokaryon, the chloroplast enveloped by three membranes, and the pusule. The flagellar apparatus also resembles that of most other dinoflagellates. The main difference is a missing or reduced striated root connective between the longitudinal microtubular flagellar root and the transverse striated flagellar root. The amphiesma includes a scale-like layer on the outside of the plasmalemma. Another unusual feature is the presence of two distinct size classes of trichocysts, measuring c. 0.2i1 µm and c. 0.7i4 µm, respectively. In their detailed construction they resemble those of other dinoflagellate trichocysts. Peridiniella catenata differs from other gonyaulacoid dinoflagellates in the presence of chloroplasts with single-stalked pyrenoids and in details of the pusular complex. The presence of two size categories of trichocysts and the outer scale-like layer have not been observed in other gonyaulacoid dinoflagellates, indicating that P. catenata is not closely related to these dinoflagellates. However, the presence of two striated collar connectives in P. catenata, a feature hitherto observed only in gonyaulacoids, implies affinity to this group.
5 The origin of the dinoflagellate plastid
Journal of Phycology, 2003
The peridinin pigmented dinoflagellate chloroplasts are the result of a secondary endosymbiotic event between a photosynthetic eukaryote and a dinoflagellate. Dinoflagellate chloroplast and nuclear evolution were independent before this endosymbiotic event. To reconstruct the evolution of the dinoflagellate chloroplast, phylogenies were constructed with a chloroplast gene psbB. The gene phylogeny should reflect the evolution of the chloroplast and indicate the plastid donor lineage. Gene sequences derived from the dinoflagellate chloroplast were extremely divergent but suggested that the plastid donor could have been a haptophyte. In an attempt to find better genes for analysis and to further understand gene transfer about 4900 randomly selected expressed genes were sequenced from two dinoflagellates, Lingulodinium polyedra and Amphidinium carterae. From these genes, thirty typically plastid-encoded Copyright by Tsvetan Radoslavov Bachvaroff 2004 ii ACKNOWLEGEMENTS The author would like to acknowledge the following individuals for their contributions to this document. Torstein Tengs taught me valuable laboratory techniques and performed many sequencing reactions on my behalf. He also made substantial intellectual contributions to my understanding of plastid evolution. Dr. David Oldach of the Institute for Human Virology generously loaned equipment and provided encouragement. Professor Robert Rowan of the University of Guam challenged me to find better data. The psbB sequences from haptophytes were obtained from Kamran Shalchian-Tabrizi in Professor Jakobsen's lab at the University of Oslo, Norway. Kamran also contributed to my understanding of dinoflagellate nuclear phylogeny by generously sharing unpublished data. Three talented undergraduates participated in the EST data collection, Ernest Williams, Gregory Concepcion, and Carolyn Rogers. Greg also contributed substantially to the dinoflagellate EST database. A fourth undergraduate, Ali Tabatabai, worked on a dinoflagellate rubisco project not presented here. Finally, I would like to thank Maria Virginia Sanchez Puerta who has read and commented on many subunits of this document, and who has sequenced the organellar genomes of Emiliania.
Ultrastructural Features of the Benthic Dinoflagellate Ostreopsis cf. ovata (Dinophyceae)
Protist, 2014
The toxic benthic dinoflagellate Ostreopsis cf. ovata has considerably expanded its distribution range in the last decade, posing risks to human health. Several aspects of this species are still poorly known. We studied ultrastructural features of cultivated and natural populations of Ostreopsis cf. ovata from the Gulf of Naples (Mediterranean Sea) using confocal laser scanning, and scanning and transmission electron microscopy. New information on the morphology and location of several sulcal plates was gained and a new plate designation is suggested that better fits the one applied to other Gonyaulacales. The microtubular component of the cytoskeleton, revealed using an anti--tubulin antibody, consisted of a cortical layer of microtubules arranged asymmetrically in the episome and in the hyposome, complemented by a complex inner microtubular system running from the sulcal area towards the internal part of the cell. The conspicuous canal was delimited by two thick, burin-shaped lobes ending in a tubular ventral opening. The canal was surrounded by mucocysts discharging their content into it. A similar structure has been reported in other benthic and planktonic dinoflagellates and may be interpreted as an example of convergent evolution in species producing large amounts of mucus.
Molecular Biology and Evolution, 2004
Recent reports show that numerous chloroplast-specific proteins of peridinin-containing dinoflagellates are encoded on minicircles-small plasmidlike molecules containing one or two polypeptide genes each. The genes for these polypeptides are chloroplast specific because their homologs from other photosynthetic eukaryotes are exclusively encoded in the chloroplast genome. Here, we report the isolation, sequencing, and subcellular localization of minicircles from the peridinin-containing dinoflagellate Ceratium horridum. The C. horridum minicircles are organized in the same manner as in other peridinin-containing dinoflagellates and encode the same kinds of plastid-specific proteins, as previous studies reported. However, intact plastids isolated from C. horridum do not contain minicircles, nor do they contain DNA that hybridizes to minicircle-specific probes. Rather, C. horridum minicircles are localized in the nucleus as shown by cell fractionation, Southern hybridization, and in situ hybridization with minicircle-specific probes. A highmolecular-weight DNA was detected in purified C. horridum plastids, but it is apparently not minicircular in organization, as hybridization with a cloned probe from the plastid-localized DNA suggests. The distinction between C. horridum and other peridinin-containing dinoflagellates at the level of their minicircle localization is paralleled by C. horridum thylakoid organization, which also differs from that of other peridinin-containing dinoflagellates, indicating that a hitherto underestimated diversity of minicircle DNA localization and thylakoid organization exists across various dinoflagellate groups.
The encystment of a freshwater dinoflagellate: A light and electron-microscopical study
British Phycological Journal, 1972
The process of encystment, or resting spore formation, in a freshwater dinoflageltate (Woloszynskia tylota nov. comb.) has been studied with both light and electron microscopy. The main features of the process are as follows: (i) the replacement of the theca by a thin, amorphous outer wall, which gradually thickens by the deposition of material on its inner face; (ii) the appearance of a layer of closely-packed lipid droplets at the cytoplasmic margin of the mature cyst, resembling a granular 'inner wall' in the light microscope; (iii) the reduction in size or disappearance of cytoplasmic structures such as chloroplasts, Golgi bodies and pusule; and (iv) the enlargement of a central 'accumulation body' and cytoplasmic vacuoles containing crystals. Comparisons are made with light-microscope studies of encystment of other dinoflagellates, with ultrastructural studies of non-motile division stages, with zooxanthellae and with fossil dinoflagellate cysts or hystrichospheres.
Protist, 2017
A gymnodinioid photosynthetic dinoflagellate was isolated from Argentina and examined by light and electron microscopy and analysis of nuclear-encoded LSU rDNA. Kirithra asteri gen. et sp. nov. was proposed as morphology and molecular phylogeny separated this dinoflagellate from others within the family Ceratoperidiniaceae. Cells were surrounded by a hyaline amphiesma comprising polygonal vesicles. Each vesicle contained a honeycomb and a trilaminar structure. An anterior sulcal extension ending in a complete circle formed the apical structure complex (ASC), which characterizes Ceratoperidiniaceae. The ASC comprised three rows of vesicles. The nucleus was located in the hypocone, and several large, irregularly shaped vesicles were present in the epi-and hypocone. Chloroplasts were surrounded by three membranes, and grana-like arrangements of thylakoids were observed in one strain used for ultrastructural study. The cell centre contained 1-3 multiple-stalked pyrenoids and membranebound vesicles containing tile-like structures surrounded each pyrenoid. Two pusules with collecting chambers and associated vesicles branched off each of the flagellar canals. The flagellar apparatus featured a ventral connective between the amphiesma and the R1 root, and almost opposite basal bodies, rarely seen in dinoflagellates. This was the first ultrastructural study of a species within Ceratoperidiniaceae. Keywords: apical structure complex; autotrophic dinoflagellates; Ceratoperidiniaceae; molecular phylogeny; ultrastructure.
The flagellar apparatus and cytoskeleton of the dinoflagellates
Protoplasma, 1991
Modem microscopical approaches have allowed more accurate investigations of the three-dimensional nature of the dinoflagellate flagellar apparatus (FA) and several other cytoskeletal protein complexes. Our presentation overviews the nature of the dinoflagellate FA and cytoskeleton in a number of taxa and compares them with those of other protists. As with other protists, the FA of the dinoflagellates can be characterized by the presence of fibrous and microtubular components. Our studies and others indicate that the dinoflagellate FA can be expected to possess a striated fibrous root on the basal body of the transverse flagellum and a multimembered microtubular root on the basal body of the longitudinal flagellum. Two other features that appear widespread in the group are the transverse striated root associated microtubule (tsrm) and the transverse microtubular root (tmr). The tsrm extends at least half the length of the transverse striated root while the tmr extends from the transverse basal body toward the exit aperture of the transverse flagelhun. In most cases, the tmr gives rise to several cytoplasmic microtubules at a right angle. The apparent conserved nature of these roots leads us to the conclusion that the dinoflagellate FA can be compared to the FA of the cryptomonads, chrysophytes, and the ciliates for phylogenetic purposes. Of these groups, the chrysophytes possess an FA with the most structures in common with the dinoflagellates. Our immunomicroscopical investigations of the microtubular, actin and centrin components of the dinoflagellate cytoskeleton point to the comparative usefulness of these cytological features.