281 research outputs found
Studies on woloszynskioid dinoflagellates IV: the genus <em>Biecheleria</em> gen. nov.
No full textUdgivelsesdato: September 2009The well known freshwater dinoflagellate Woloszynskia pseudopalustris is transferred to the new genus Biecheleria, based on the very unusual structure of the eyespot (comprising a stack of cisternae), the apical apparatus of a single elongate amphiesma vesicle, the structure of the resting cyst, and molecular data. Biecheleria is phylogenetically related to Symbiodinium and Polarella of the family Suessiaceae. This family, which extends back to the Jurassic, is redefined with the eyespot (Type E sensu Moestrup and Daugbjerg) and apical apparatus as diagnostic features, unknown elsewhere in the dinoflagellates. Biecheleria also comprises the brackish water species Biecheleria baltica sp. nov. (presently identified as Woloszynskia halophila) and the marine species Biecheleria natalensis (syn. Gymnodinium natalense). Gymnodinium halophilum described in 1952 by B. Biecheler but apparently not subsequently refound, is transferred to Biecheleria. The Suessiaceae further includes the marine species Protodinium simplex, described by Lohmann in 1908 but shortly afterwards (1921) transferred to Gymnodinium by Kofoid and Swezy and subsequently known as Gymnodinium simplex. It only distantly related to Gymnodinium. A new family, the Borghiellaceae, is proposed for the sister group to the Suessiaceae, based on eyespot structure (Type B of Moestrup and Daugbjerg), the morphology of the apical apparatus (if present), and molecular data. It presently comprises the genera Baldinia and Borghiella. Cells of Biecheleria pseudopalustris and B. baltica contain a microtubular strand (msp) associated with vesicles containing opaque material. Such structures are known in other dinoflagellates to serve as a peduncle, indicating that the two species may be mixotrophic
On the classification of the genera Labyrinthula, Schizochytrium and Thraustochytrium (Labyrinthulids and Thraustochytrids)
No full textSpecies of the genera Labyrinthula, Schizochytrium, Thraustochytrium and related organisms have recently attracted attention in biotechnology, and here is a short note on how to classify these rather special organisms
Studies on woloszynskioid dinoflagellates II: on Tovellia sanguinea sp. nov., the dinoflagellate responsible for the reddening of Lake Tovel, N. Italy
No full textplankton, alger, Tovel, dinoflagellaterAbstract The organism responsible for the former annual reddening of Lake Tovel in the Italian Alps (up to 1964) has been identified and studied in detail. Considerable confusion exists regarding the identity of this organism, and the detailed description by Baldi in 1941 is now believed to be based on more than one organism. Baldi's red and green forms appear to be two different organisms, both of which have now been isolated into unialgal culture and studied using light microscopy, electron microscopy, and sequencing of the large subunit of ribosomal DNA (LSU rDNA). The organism has been found in three lakes in the area, but only in Lake Tovel have conditions allowed for reddening of the water during summer. The name of the organism believed to be the cause of the reddening, Glenodinium sanguineum Marchesoni, used in numerous publications, is an illegitimate homonym of G. sanguineum H.J. Carter, and the organism is described here as a new species, Tovellia sanguinea sp. nov., the seventh species of the newly described genus Tovellia. T. sanguinea is closely related to the other red-coloured species of Tovellia, Tovellia coronata (previously known as Woloszynskia coronata) but differs in several morphological features, notably the chloroplast arrangement, and in LSU rDNA sequence divergence (11-12%). Cells preserved from Lake Tovel during a reddening phenomenon in 1938 have been re-examined by scanning electron microscopy and agree morphologically with the new isolates. Tovellia sanguinea is a species of oligotrophic or mesotrophic-oligotrophic cold-water lakes, in which the average summer temperature does not exceed 15°C. It occurs on both calcareous (as in Lake Tovel) and non-calcareous substrata (as in the other two lakes). </table
Studies on woloszynskioid dinoflagellates V. Ultrastructure of Biecheleriopsis gen. nov., with description of Biecheleriopsis adriatica sp. nov.
No full textUdgivelsesdato: September 2009An isolate of the very small marine dinoflagellate Biecheleriopsis adriatica gen. et sp. nov. (12-15 µm long) has been examined by light, scanning and transmission electron microscopy, combined with partial sequencing of nuclear-encoded large subunit rRNA. Biecheleriopsis is a genus of thin-walled dinoflagellates, related to Biecheleria and the taxonomic group of Polarella, Protodinium and Symbiodinium, the latter comprising mainly symbionts of marine invertebrates. The mixotrophic Biecheleriopsis adriatica is characterized by: (i) a special type of apical furrow apparatus; (ii) an eyespot of Type E sensu Moestrup and Daugbjerg; (iii) an unusual type of pyrenoid; and (iv) a spiny resting cyst. Thin sections showed the presence a fibrous connection between the flagellar apparatus and a finger-like extension of the nucleus ('rhizoplast'). It forms a physical connection between the flagella and the nucleus. This unusual structure has previously been considered to characterize the 'true' gymnodinioids, represented by Gymnodinium sensu Daugbjerg et al. and related forms. However, the apical furrow apparatus and the nuclear envelope of Biecheleriopsis are woloszynskioid rather than gymnodinioid. The related genus Biecheleria lacks a rhizoplast, and it also lacks a 51-base pair fragment of domain D2 of the large subunit rRNA, which is present in other woloszynskioids. A physical connection between the flagellar apparatus and the nucleus mediated by a fibrous structure is known in other groups of protists, for example, the 'rhizoplast' of many heterokont flagellates, some green algal flagellates, etc. The phylogenetic significance of a rhizoplast in two groups of dinoflagellates that are only distantly related is presently difficult to assess
Studies on woloszynskioid dinoflagellates III::on the ultrastructure and phylogeny of Borghiella dodgei gen. et sp nov., a cold-water species from Lake Tovel, N. Italy, and on B-tenuissima comb. nov (syn. Woloszynskia tenuissima)
No full textUdgivelsesdato: Jan 2008Using ultrastructure and nuclear-encoded large subunit (LSU) rDNA sequences, the woloszynskioid dinoflagellates have been shown recently to form a polyphyletic assemblage. The first group comprises the family Tovelliaceae, with the genera Tovellia and Jadwigia. The present manuscript describes the second group, comprising Borghiella dodgei gen. et sp. nov. from the Italian Alps. The new genus differs in a number of ultrastructural features, of which the most important are the structure of the eyespot (type B sensu Moestrup & Daugbjerg) and the structure of the apical part of the cell. The resting cyst is smooth, in contrast to the cysts of other woloszynskioids such as Tovellia and some species of Woloszynskia. The new species has been previously confused with Tovellia sanguinea, which was responsible for colouring the water of Lake Tovel, in the Italian Alps, blood-red up to 1964. However, B. dodgei may form brown, never truly red blooms as in the case of T. sanguinea. The transverse flagellum of Borghiella carries, in addition to thin hairs found also in other dinoflagellates, a row of shorter, thicker hairs resembling the curly hairs on the homologous, anterior flagellum of the perkinsid Parvilucifera but apparently not observed in any other dinoflagellates. Woloszynskia tenuissima, a well-known cold-water dinoflagellate, has been re-examined using material isolated from Greenland. Based on partial LSU rDNA sequencing it is shown to be related to R dodgei (sequence divergence only 1.1%) and is transferred to this genus as B. tenuissima comb. nov. We agree with the observations of von Stosch that the cysts of this species are spherical and smooth, in contrast to what was mentioned in the original description by Woloszynska
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