Diversity of swimming behavior in Pyramimonas (Prasinophyceae)

High‐speed videography and inverted light microscope observations of cultures of several Pyramimonas Schmarda species (Pyramimonas chlorina Sym et Pienaar, Pyramimonas disomata McFadden Hill et Wetherbee, Pyramimonas gelidicola McFadden Wether‐bee et Moestrup, Pyramimonas mantoniae Moestrup et Hill, Pyramimonas melkonianii Sym et Pienaar, Pyramimonas mitra Moestrup et Hill, Pyramimonas moestrupii McFadden, Pyramimonas mucifera Sym et Pienaar, Pyramimonas nephroidea McFadden, Pyramimonas orientalis McFadden Hill et Wetherbee, Pyramimonas parkeae Norris et Pearson, Pyramimonas propulsa Moestrup et Hill) revealed swimming behavior to be much more diverse than originally reported for the genus. This diversity shows gradation between extremes of recurved flagellar beating and non‐biphasic ciliary beating. Comparison with the behavior of presumably more primitive members of the Pyramimonadales (Cymbomonas tetramitformis Schiller and Pterosperma cristatum Schiller) leads to the conclusion that the former condition is primitive and the gradation may assist in reconstructing phylogenetic relationships within the genus Pyramimonas, particularly as it is consistent with phylogenies derived from ultrastructural and molecular data.     

AN ADDITIONAL PUNCTATE SPECIES OF PYRAMIMONAS, P. FORMOSA, SP. NOV., AND ITS IMPACT ON THE SUBGENERA PUNCTATAE AND PYRAMIMONAS (PRASINOPHYCEAE, CHLOROPHYTA)

A new punctate species of Pyramimonas Schmarda from South Africa is described. This species is somewhat anomalous and, like P. chlorina Sym et Pienaar (subgenus Pyramimonas McFadden), has characters that bridge the divide between the subgenera Pyramimonas and Punctatae McFadden. Features of these two species, together with the lack of exclusive character sets for either subgenus derived from other species of these subgenera, lead to the conclusion that Punctatae now should be subsumed formally into the subgenus Pyramimonas.     

Starch in prasinophycean algae

Reserve products isolated from three species of prasinophycean algae: Pyramimonas parkeae Norris and Pearson, Pyramimonas amylifera Conrad and Platymonas tetrathele West were compared. Three pieces of experimental evidence indicate that the reserve product of each of the species analyzed is a true starch. (I) There is no essential difference between the light absorption curve for the complex formed between corn starch and iodine and the corresponding curves for the algal products. (2) The β-amylase breakdown limit of these compounds is very close to that of corn starch. (3) The X-ray diffraction diagrams produced by the reserve material from Pyramimonas parkeae and Platymonas tetrathele is a so-called A-spectrum characteristic of cereal starches while the diagram produced by grains from Pyramimonas amylifera corresponds to the B-spectrum typical for tuber starches. The dissimilarity between the X-ray diagrams produced by the starches from the Pyramimonas species suggests that a re-examination of the taxonomy of these species is warranted.     

THE ULTRASTRUCTURE OF PYRAMIMONAS PSEUDOPARKEAE SP. NOV. (PRASINOPHYCEAE) FROM SOUTH AFRICA1

The ultrastructure of Pyramimonas pseudoparkeae sp. nov., a member of the class Prasinophyceae occurring in tidal pools along the east, south and west coast of South Africa, is described. The cell surface is covered by three distinctive body scales whilst the flagellar surfaces possess four types of scales. The structure of these scales is described. P. pseudoparkeae resembles Pyramimonas parkeae Norris and Pearson but differs in the structure of the type 2 body scale. The symmetry and ultrastructure of the cell are described with special attention given to the flagellar apparatus. Preliminary information on the life cycle of this species is presented. This new species is compared with other closely related members of the genus Pyramimonas.     

Further observations on the type species of Pyramimonas (P. Tetrarhynchus Schmarda) (Prasinophyceae): an examination by light microscopy, together with notes on its taxonomy

Previous records of Pyramimonas tetrarhynchus are examined, and a morphological variant is designated as var.lobata var.nov.
The species was studied by light microscopy using cultured material, as a supplement to investigations with the electron microscope published separately. Particular attention was paid to aspects of cell symmetry at various stages of division.     

Serial reconstruction of the mitochondrial reticulum in the antarctic flagellate,Pyramimonas gelidicola (Prasinophyceae,Chlorophyta)

Summary A serial reconstruction ofPyramimonas gelidicola McFadden, Moestrup andWetherbee has revealed a large reticulated mitochondrion branching throughout the cell. The possibility of single mitochondria in other members of thePrasinophyceae and the uniformity of the morphology of this organelle within the class is discussed.     

Fine structure of Pyramimonas octopus sp. nov., an octoflagellated benthic species of Pyramimonas (Prasinophyceae), with some observations on its ecology

A new octoflagellated species of Pyramimonas is described from three localities in Denmark. It is characterized by its ecology, being a marine psammophilic species associated with sand grains, and by details of the scaly covering on the cell surface. In the scale cover there are similarities to P. amylifera and to P. tetrarhynchus. P. octopus is distinguished by the possession of circular body scales of a type not previously found in the genus.
The general fine structure of the new species is described with emphasis on scale structure, the internal structure of the cell body and the flagella.     

The Disruption of Dictyosome Structure, Polarity and Secretory Activity in the Scale-producing Green Alga, Pyramimonas inconstans

Domozych, D. S. and Korbusieski, T. J. 1985. The disruptionof dictyosome structure, polarity and secretory activity inthe scale-producing green alga Pyramimonas inconstans.—J.exp.Bot.36: 1304–1312. Dictyosome morphology and scale morphogenesis in the green alga,Pyramimonas inconstans, are well-defined ultrastructurally.By applying the sodium-specific ionophore, monensin, to actively-growingcell cultures, both dictyosome micro-architecture and the scale-basedsecretory pathway can be significantly altered. Applicationof 0.1 mol m³ and 0.01 mol m ^–3monensin for short periods(1 -3 h) results in cisternal curling and the disorientationof dictyosome polarity. Prolonged exposure to the ionophore(4-24 h) results in the complete disruption of dictyosome morphologyand scale morphogenesis with the emergence of irregular vesiclesfrom the maturing face. Removal of monensin by repeated washingreturns dictyosome structure and secretory activity to normal.These results indicate that Golgi apparatus integrity and secretoryactivity in Pyramimonas may be controlled by a localized, cytoplasmicproton gradient Key words: Monensin, Pyramimonas, dictyosome     

The flagellar apparatus of the scaly green flagellatePyramimonas obovata: Absolute configuration

Summary The flagellar apparatus of the quadriflagellate scaly green algaPyramimonas obovata has been studied in detail and the absolute configuration of the flagellar apparatus has been determined. The flagellar root system is cruciate (4-2-4-2-system). 18 major basal body associated fibrous structures connect the four basal bodies with each other. Each basal body is linked to an adjacent basal body by a unique set of connecting fibres, i.e., the flagellar apparatus does not exhibit 180° rotational symmetry. The flagellar apparatus ofPyramimonas obovata is compared with that of quadriflagellate motile cells of theChlorophyceae sensu Stewart andMattox and the phylogenetic relationships are discussed.     

Observations on the microanatomy of the type species of Pyramimonas (P. tetrarhynchus Schmarda)

Salient features of microanatomy of Pyramimonas tetrarhynchus , type species of the genus, are described and illustrated. The species is shown to possess a flagellar scale reservoir comparable to that previously described for a marine species (P. amylifera) though somewhat simpler. The body scales are shown to arise directly from Golgi eisternae as in P. amylifera. Other features discussed include the flagellar roots and certain aspects of the mode of liberation of scales to the exterior. Participation by endoplasmic reticulum in the latter process is shown to be probable but there is no precise explanation forthcoming for the elaborate scale arrangement encountered both on the flagella and on the cell. Participation by cytoplasmic tubules is nevertheless effectively excluded for the latter.     

The external morphology of the type species of Pyramimonas (P. tetrarhynchus Schmarda) by electron microscopy

Pyramimonas tetrarhynchus has been grown in culture and its external features examined using direct preparations and sections. The flagellar and body scales are described and compared with those of previously investigated species.     

A third layer of body scales in Pyramimonas tetrarhynchus Schmarda

Examination of a clone of Pyramimonas tetrarhynchus Schmarda (the type species) collected in Cambridge, revealed a third, outer, layer of elaborate body scales different from the underlying ones. Re-investigation of another clone showed that it also had this outer layer, previously undetected.     

Sterols of marine microalgae Pyramimonas cf. cordata (Prasinophyta), Attheya ussurensis sp. nov. (Bacillariophyta) and a spring diatom bloom from Lake Baikal

The free sterol compositions of two marine microalgal species Pyramimonas cf. cordata (Prasinophyta), Attheya ussurensis sp. nov. (Bacillariophyta), and diatom bloom samples from Lake Baikal were determined by gas chromatography, gas chromatography-mass spectrometry and (for some sterol constituents) using nuclear magnetic resonance spectra. A variety of sterol profiles were found. The principal sterol in the prasinophyte P. cf. cordata, collected in the Sea of Japan near Vladivostok, was 24(R)-ethylcholesta-5,22E-dien-3beta-ol (poriferasterol), but not 24-ethyl-5,24(28)Z-dien-3beta-ol, as reported earlier in the related species Pyramimonas cordata. The principal sterol in the marine diatom A. ussurensis sp. nov. was identified as 24-ethylcholest-5-en-3beta-ol. The sample of diatom bloom caused by Stephanodiscus meyerii with admixtures of several other diatom species, contained cholesterol and 24-methylcholesta-5,24(28)-dien-3beta-ol as main sterol constituents.     

Pyramimonas tychotreta, sp. nov. (prasinophyceae), a new marine species from antarctica: light and electron microscopy of the motile stage and notes on growth rates

An undescribed marine prasinophyte, Pyramimonas tychotreta, sp. nov., was isolated from a water sample collected near the ice edge in the Weddell Sea (Antarctica) and is characterized by means of light and electron microscopy. This is the second described Antarctic species in the genus and it possesses a cell ultrastructure typical for members of the subgenus Vestigifera McFadden. The quadriflagellated cells measure 8–12 μm in length and 6–7 μm in width and are equipped with seven types of organic scales that cover the flagella and cell body. The scale floor of the box scales is ornamented by quadrants of parallel striations running perpendicular to one another. The scale floor is further characterized by a number of randomly positioned perforations. The wall of the box scales may be solid or possess up to five perforations. The base of the crown scales is square with rounded corners. It is formed of two crossed ribs, the extremities of which are interconnected by a peripheral rib. Four upright arms, attached to the peripheral rib in positions slightly offset from its junction with the cross ribs, join up with the distal extremity of a central upright strut. Each arm possesses two spines. The limuloid scales are cross‐striped by 10–12 ribs. Some details of the flagellar apparatus are briefly reported. Pyramimonas tychotreta is compared with other species of the genus. Experiments were conducted to study the response of growth rate to variations in temperature and salinity in the clonal culture. The best growth rate (0.45 divisions·24 h ^{? 1}) was found at 4.6° C; growth ceased at temperatures in excess of 12° C. Growth in salinities ranging from 15 to 35 psu was similar, but was arrested at 10 psu. These studies suggest that P. tychotreta as a cold stenotherm and euryhaline taxon. New observations are presented on the geographic distribution of previously described species of Pyramimonas Schmarda from the Northern Foxe Basin, Canada.     

PHYLOGENY OF THE GENUS PYRAMIMONAS (PRASINOPHYCEAE,CHLOROPHYTA) INFERRED FROM THE rbcL GENE1

A 1089-basepair fragment (approx. 75%) of the large subunit of the chloroplast-encoded gene, ribulose-1,5-bis-phosphate carboxylase/oxygenase (rbcL), was sequenced from 16 species of the genus Pyramimonas Schmarda. Electron microscopic and biochemical studies of Pyramimonas, one of the most morphologically diverse genera within the potential sister groups to the chlorophyll a- and b-containing plants, suggest that this genus consists of at least four separate subgenera. Using the homologous sequence of rbcL from Cymbomonas tetramitiformis Schiller (Halosphaeraceae) as an outgroup and applying the maximum likelihood method, we show that the inferred topology is congruent with traditional delimitations of the taxa based on observations of periplast, internal ultrastructure, and biochemical features. A bootstrap analysis also supports division at the subgeneric level; however, the low bootstrap support associated with the deep nodes precludes resolution of these branches. A maximum likelihood relative rate test revealed that the rbcL gene in these single-celled green flagellates has a heterogeneous rate of substitution. The rbcL gene in species of the subgenus Pyramimonas has evolved at an accelerated rate relative to that of congenerics.     

DIEL CHANGES IN THE COMPOSITION OF PHOTOSYNTHETIC PIGMENTS AND CELLULAR CARBON AND NITROGEN IN PYRAMIMONAS PARKEAE (PRASINOPHYCEAE)1

Diel changes in mean cell volume, cellular carbon (carbon content per cell), cellular Chl a, C/N ratio, Chl a/carbon ratio and pigment composition were determined for an axenic clonal culture of Pyramimonas parkeae Norris et Pearson through three 12:12 h LD cycles in a laboratory culture tank of 1 m³. Mean cell volume and cellular C, N and most pigments increased during the light period as a result of photosynthesis and decreased with an increase in cell density by phased cell division during the dark period. Chi a and Chi b increased in a parallel manner during the light period. Increases in the diel synthesis pattern of carotenoids varied. Violaxanthin and lutein content increased for a few hours at the beginning of the light period and preceeded that of neoxanthin. The diel synthesis pattern of neoxanthin was similar to that of Chi a. Increases of loroxanthin and its ester form were slower than that of Chi a at the beginning of the light period. A net increase of α-carotene was observed during the dark period. Mass spectroscopy of carotenoid structure showed a new xanthophyll, loroxanthin dodecenoate, in this species.     

Neue Arten der Gattung Pyramimonas Schmarda

Zusammenfassung Es wird auf eine grosse Formenfülle der Gattung Pyramimonas hingewiesen. Mehrere neue Arten and eine neue Varietät, die in Nordmähren (Tschechoslowakei) gefunden werden, werden erwähnt und abgebildet. Folgende Arten werden beschrieben: Pyramimonas recta, P. fasciata, P. radiata, P. conradii, P. cribrum, P. polychloris, P. rapa, P. pluristigma, P. fabelliformis und die Varietdt P. reticulata var. conica.

---

Summary The great number of Pyramimonas-species is discussed. Some new species, found in Nordmähren (Czechoslovakia) are described and pictured. The new species described are: Pyramimonas recta, P. fasciata, P. radiata, P. conradii, P. cribrum, P. polychloris, P. rapa, P. pluristigma, P. fabelliformis and the variety P. reticulata var. conica.

     

Light and electron microscopical studies onHafniomonas gen. nov. (Chlorophyceae,Volvocales), a genus resemblingPyramimonas (Prasinophyceae)

Based on light and electron microscopical studies ofPyramimonas reticulata the genusPyramimonas is shown to contain a number of unrelated flagellates.P. reticulata andP. montana are transferred to the new genusHafniomonas, cells of which differ fromPyramimonas in shape, in the absence of scales and hairs on the body and flagellar surfaces, in details of the chloroplast, the position of the nucleus, the Golgi apparatus, the internal structure of the flagellar apparatus, and in cell division. The prasinophytePyramimonas contains a characteristic association of a large microbody and a rhizoplast, situated on the nuclear surface. A similar association is being found in an increasing number of prasinophycean flagellates, but is absent inHafniomonas, which is considered related to chlorophycean rather than prasinophycean flagellates. The phylogenetic position ofHafniomonas is discussed, based in particular on details of the unique flagellar apparatus.     

FINE STRUCTURE OF CELL DIVISION IN PYRAMIMONAS PARKEAE NORRIS AND PEARSON (CHLOROPHYTA,PRASINOPHYCEAE)1

Cell division in Pyramimonas parkeae is described and compared with some other green algae. The first indication of mitosis is division of the chloroplast, accompanied by growth of a prominent microbody, followed by replication of the 4 basal bodies. Also closely timed with this is the replication of the Golgi and other components of the basal body complex. Two basal body complexes separate, each taking a position at either pole of the nucleus which has migrated to a characteristic position just beneath the plasmalemma of a broadened and flattened flagellar pit. Cytokinesis is accomplished by the fusion of ducts and vesicles with the simultaneous release of scales to the newly formed exterior. Cells swim throughout division.