ULTRASTRUCTURAL STUDIES ON THE BLUE-GREEN ALGAL SYMBIONT IN CYANOPHORA PARADOXA KORSCHIKOFF

Studies conducted on the ultrastructure of Cyanophora paradoxa Korschikoff (a cryptomonad) have shown that its intracellular symbiont is closely related to unicellular blue-green algae. Due to its peculiar habitat, the intracellular symbiont lacks the characteristic cyanophycean double-layered cell wall, but is surrounded by a thin protoplasmic membrane. The protoplasm itself is differentiated into a lamellated chromatoplasm containing photosynthetic pigments, polyphosphate granules, and possible oil droplets, and a non-lamellar centroplasm with a large centrally located electron-opaque body surrounded by a fibril-containing halo. This halo-central body complex may be nuclear in nature. Binary fission of the organism is described. Since this cyanelle has not yet been classified, we name it Cyanocyta korschikoffiana nov. gen. nov. sp.; and because of its structural peculiarities, we find it necessary to create a new family for it, Cyanocytaceae, in the order Chroococcales.     

TAXONOMIC STUDY OF BIGELOWIELLA LONGIFILA SP. NOV. (CHLORARACHNIOPHYTA) AND A TIME‐LAPSE VIDEO OBSERVATION OF THE UNIQUE MIGRATION OF AMOEBOID CELLS1

A new species of a chlorarachniophyte alga, Bigelowiella longifila sp. nov., is described. It is classified as a member of Bigelowiella as flagellate cells constitute the main stage of the life cycle. However, this alga is different from the only described species of the genus, B. natans Moestrup, in having a unique amoeboid stage in the life cycle. We observed an interesting behavior of amoeboid daughter cells after cell division: One of the two daughter cells inherits the long filopodium of the parental cell, and it subsequently transports its cell contents through the filopodium to develop at its opposite end. The other daughter cell forms a new filopodium. This unequal behavior of daughter cells may have evolved before the chlorarachniophytes and some colorless cercozoans diverged.     

Research note: Amorphochlora amoebiformis gen. et comb. nov. (Chlorarachniophyceae)

A chlorarachniophycean alga, Lotharella amoebiformis, which has been classified in the genus Lotharella is placed into a new genus Amorphochlora gen. nov., based on its phylogenetic position, which has been clarified by the recently accumulated molecular phylogenetic information, and the morphological difference between the vegetative cells of the Lotharella species. Following this taxonomic treatment, a new combination Amorphochlora amoebiformis comb. nov., is proposed.     

Two New Kremastochrysopsis species,K. austriaca sp. nov. and K. americana sp. nov. (Chrysophyceae)1

Melting summer snow in the Austrian Alps exhibited a yellowish bloom that was mainly comprised of an unidentified unicellular chrysophyte. Molecular data (18S rRNA and rbcL genes) showed a close relationship to published sequences from an American pond alga formerly identified as Kremastochrysis sp. The genera Kremastochrysis and Kremastochrysopsis are morphologically distinguished by the number of flagella observed with the light microscope, and therefore we assigned the Austrian snow alga and an American pond alga to the genus Kremastochrysopsis. Transmission and scanning electron microscopy revealed that swimming cells had two flagella oriented in opposite directions, typical for the Hibberdiales. Molecular phylogenetic analyses showed that both new species were closely related to Hibberdia. Kremastochrysopsis ocellata, the type species and only known species, has two chloroplasts per cell and the zoospores have red eyespots. Our two organisms had only a single chloroplast and no zoospore eyespot, but their gene sequences differed substantially. Therefore, we described two new species, Kremastochrysopsis austriaca sp. nov and Kremstochrysopsis americana sp. nov. When grown in culture, both taxa showed a characteristic hyponeustonic growth (hanging below the water surface), whereas older immotile cells grew at the bottom of the culture vessel. Ecologically, Kremastochrysopsis austriaca sp. nov., which caused snow discolorations, had no close phylogenetic relationships to other psychrophilic chrysophytes, for example, Chromulina chionophilia, Hydrurus sp., and Ochromonas-like flagellates.     

Lotharella vacuolata sp. nov., a new species of chlorarachniophyte algae, and time-lapse video observations on its unique post-cell division behavior

A new species of chlorarachniophyte alga, Lotharella vacuolata Ota et Ishida sp. nov., is described. This alga has been maintained as strain CCMP240 at the Provasoli‐Guillard National Center for Culture of Marine Phytoplankton at Bigelow Laboratory for Ocean Sciences. We examined in detail its morphology, ultrastructure and life cycle, using light microscopy, transmission electron microscopy and time‐lapse videomicroscopy. The dominant stage in the life cycle was represented by coccoid cells; however, amoeboid and flagellated stages were also observed. This alga showed unique post‐cell division behavior: one of the two daughter cells became amoeboid and escaped through a pore on the parental cell wall; the other daughter cell remained within the parental cell wall. Pyrenoid ultrastructure and nucleomorph location, which are used as the main generic criteria of chlorarachniophytes, confirmed that the strain CCMP240 is a member of Lotharella. This alga, however, was clearly distinguished from other known Lotharella species by the presence of large vacuoles, unusual post‐cell division behavior and some unique ultrastructural characters.     

Lotharella amoeboformis sp. nov.: A new species of chlorarachniophytes from Japan

The ultrastructure, morphology and life cycle of a new chlorarachniophyte alga collected from Okinawa in Japan have been studied. The life cycle of this alga consists of amoeboid, wall‐less round, coccoid and flagellated cells in culture condition; however, the coccoid and flagellate cells are very rare. The pyrenoid ultra‐structure of this alga is the same as that of a previously described species, Lotharella globosa. Since pyrenoid ultrastructure has been adopted as the main criterion for the generic classification of the chlorarachniophytes, the present alga is placed in Lotharella. However, the present alga has a dominant amoeboid cell stage and a reduced walled‐cell stage in the life cycle, while in L. globosa, the walled‐cell stage is dominant and there is no amoeboid cell stage. Therefore the present alga is described as a new species of Lotharella: Lotharella amoeboformis Ishida et Y. Hara sp. nov.     

Kleine Mitteilungen über Flagellaten und Algen

Zusammenfassung Die unter dem Namen Anacystis nidulans für wichtige physiologische Zwecke verwendete Cyanophycee bildet unter Umständen mehrzellige Fäden. Sie sollte deshalb vielleicht nicht wie bisher zu den Chroococcales gestellt werden. Da sie auch keine eigentlichen Trichome und keine Hormogonien hervorbringt, kann sie auch nicht bei den Hormogenales eingeordnet werden.Für diese Cyanophycee wird der neue Gattungsname Lauterbornia vorgeschlagen. Die einzige Art L. nidulans (Richter) nov. gen., nov. comb. zeigt eigenartige ernährungsphysiologische Züge.

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Short contributions on flagellates and algaeXVI. Lauterbornia (Anacystis) nidulans (Richter) nov. gen., nov. comb. Cyanophyceae

Summary Under the name Anacystis nidulans a Cyanophycean form has been used for important physiological investigations. Since the alga is able to produce filaments composed of a number of cells it should not perhaps be grouped among Chroococcales as hitherto done. It also does not possess proper trichomes nor hormogonia and may not therefore be considered to be a member of the Hormogenales.The new generic name Lauterbornia is therefore proposed, so that the organism is to be called Lauterbornia nidulans (Richter) nov. gen., nov. comb. It is also peculiar physiologically by a tendency to mixotrophy of the mainly phototrophic alga.

     

Phylogeny and Establishment of a New Ciliate Family,Wilbertomorphidae fam. nov. (Ciliophora,Karyorelictea), a Highly Specialized Taxon Represented by Wilbertomorpha colpoda gen. nov., spec. nov.

The morphology and molecular phylogeny of a new marine interstitial karyorelictean ciliate, Wilbertomorpha colpoda gen. nov., spec. nov., isolated from a sandy beach at Qingdao, China, are investigated. The ciliature is mainly on the right surface with the left surface barren except for a single marginal kinety, which is typical of the order Loxodida. Nevertheless, other morphological features, such as the highly reduced buccal structure, the absence of a buccal cavity and the presence of extremely specialized cortical granules, prevent its assignation to any known family. Furthermore, the secondary structure of the variable region 2 of the SSU rRNA gene is unique among loxodids. Thus, we establish a new family, Wilbertomorphidae fam. nov. for the genus Wilbertomorpha. Phylogenetic analyses based on SSU rRNA gene sequence data suggest that this taxon is a sister group to the family Geleiidae which belongs to the order Protoheterotrichida. However, morphologically Wilbertomorpha bears a much stronger resemblance to Loxodidae which belongs to the order Loxodida. Based on these findings, we tentatively place Wilbertomorphidae nov. fam. incertae sedis within Karyorelictea.     

MORPHOLOGY AND SYSTEMATICS OF SCIUROTHAMNION STEGENGAE GEN. ET SP. NOV. (CERAMIACEAE,RHODOPHYTA) FROM THE INDO‐PACIFIC1

A new ceramiaceous alga, Sciurothamnion stegengae De Clerck et Kraft, gen. et sp. nov., is described from the western Indian Ocean and the Philippines. Sciurothamnion appears related to the tribe Callithamnieae on the basis of the position and composition of its procarps and by the majority of post‐fertilization events. It differs, however, from all current members of the tribe by the presence of two periaxial cells bearing determinate laterals per axial cell. Additionally, unlike any present representative of the subfamily Callithamnioideae, no intercalary foot cell is formed after diploidization of the paired auxiliary cells. The genus is characterized by a terminal foot cell (“disposal cell”), which segregates the haploid nuclei of the diploidized auxiliary cell from the diploid zygote nucleus. The nature of three types of foot cells reported in the Ceramiaceae (intercalary foot cells containing only haploid nuclei, intercalary foot cells containing haploid nuclei and a diploid nucleus, and terminal foot cells containing only haploid nuclei) is discussed.     

Ultrastructure ofCyanoptyche gloeocystis f.dispersa (Glaucocystophyceae)

Cyanoptyche gloeocystis f.dispersa (Geitler)Starmach is a palmelloid colonial alga that contains prokaryotic blue-green endocytobionts (cyanelles) instead of chloroplasts. The periphery of the host cell shows a peculiar lacunae system with underlying microtubules. Vegetative cells possess two rudimentary flagella. Zoospores are dorsiventrally shaped with two heterokont and heterodynamic flagella which originate from a subapical depression. This depression can also be seen in vegetative cells. Both flagella possess non-tubular mastigonemes. Main reserve product is starch lying freely in the cytoplasm. Cyanelles, enclosed singly in a host vesicle, are provided with a remnant cell wall. Thylakoids are arranged concentrically. The central part of each cyanelle harbours its DNA and one large polyhedral body, probably a carboxysome.Cyanoptyche gloeocystis f.dispersa shares all taxonomically essential characters with the monadoidCyanophora, the palmelloidGloeochaete, and the coccoidGlaucocystis. All of them are members of the cyanelle-bearing small algal classGlaucocystophyceae. Members of this class serve as model organisms for the evolution of chloroplasts from cyanophycean ancestors.Dedicated to Prof. DrLothar Geitler on the occasion of his 90th birthday.     

A new aerial alga, Stichococcus ampulliformis sp. nov. (Trebouxiophyceae, Chlorophyta) from Japan

A new aerial alga, Stichococcus ampulliformis S. Handa sp. nov. (Trebouxiophyceae, Chlorophyta) is described based on a clone isolated from the bark of Cephalotaxus harringtonia (Knight ex Forbes) K. Koch collected from Taishaku‐kyo Gorge, Hiroshima Prefecture, south‐west Japan. This alga was examined by light microscopy and transmission electron microscopy and subjected to molecular phylogenetic analysis. Based on its morphological features and life‐cycle, especially short filament formation, the alga was assigned to the genus Stichococcus Nägeli. However, this alga differs from other described Stichococcus species in that it reproduces by a form of ‘budding’, producing two daughter cells of different sizes. The larger cell, enclosed within the mother cell wall, soon reaches the size of a normal vegetative cell. The smaller cell is extruded and takes longer to reach full vegetative size. A phylogenetic tree constructed using 18S rRNA sequences indicated that, within the Trebouxiophyceae, S. ampulliformis is closely related to S. bacillaris Nägeli and some species of Prasiola Meneghini.     

Vacuolar granules in Chlamydomonas reinhardtii: polyphosphate and a 70-kDa polypeptide as major components

The alga Chlamydomonas reinhardtii contains cytoplasmic vacuoles that are often filled with a dense granule that is released from the cell by exocytosis. Purified granules contained polyphosphate, complexed with calcium and magnesium, as the predominant inorganic components. Antiserum was raised against the major 70-kDa protein in granules purified from wall-deficient (cw15) mutants, which reacted on immunoblots with larger glycoprotein complexes in purified cell wall fractions from wild-type cells. Confocal fluorescence microscopy detected binding of these antibodies predominantly at the periphery of wall-containing C. reinhardtiiy1 cells but primarily to loci in the interior of cells of the cw15 strain. Immunoelectron microscopy demonstrated that the 70-kDa protein was localized in vacuolar granules and the trans-Golgi network in sections of cw15 cells but not in the cytosol or chloroplast. Treatment of cells with a dye, fluorescent in its protonated form, indicated that the pH within vacuoles was lower than that in the cytosol, which suggested that the vacuoles are similar to lysosomes. Thus, the vacuoles may serve a dual function to provide an environment for degradation within the cell and also serve as a vehicle for secretion of specific proteins. Received: 29 September 1999 / Accepted: 20 November 1999     

<Emphasis Type="Italic">Elliptochloris bilobata</Emphasis> var. <Emphasis Type="Italic">corticola</Emphasis> var. nov. (Trebouxiophyceae,Chlorophyta), a novel subaerial coccal green alga

We investigated a previously unidentified subaerial corticolous strain of the genus Elliptochloris Tschermak-Woess. The alga shares the generic morphological characters with Elliptochloris bilobata, the type species of the genus, but it has a thicker cell wall of adult globular cells, different chloroplast structure and it also differs in shape of elliptical autospores. The differences of the autospore shape between both species were evaluated using landmark-based geometric morphometrics. The 18S rDNA gene sequence of the new alga forms a monophyletic clade with the authentic strain of E. bilobata within the green algal class Trebouxiophyceae close to representatives of the genus Coccomyxa. We describe the new alga as Elliptochloris bilobata var. corticola var. nov. Presented at the International Symposium Biology and Taxonomy of Green Algae V, Smolenice, June 26–29, 2007, Slovakia.     

Fine Structure of Blue-Green Algae and the Cells Lined along the Endophyte Cavity in the Coralloid Root of Cycas

The ultrastructure of vegetative cells of blue-green alga, Anabaena cycadae, in the coralloid root of Cycas revoluta has the general characteristics of the cyanophycean cells. Their heterocysts are characterized by heavy envelope deposition, well developed pore channel with its plug, absence of large granules as inclusions and reduced and flattened photosynthetic thylakoids. By these characteristical features, the frequency of heterocysts occurring in this algal population of the coralloid root may be estimated to ca. 40%. This high heterocyst frequency is a sign of relatively high activity of nitrogen fixation in this symbiont. The ultrastructure of the cells lined along the endophyte cavity in the coralloid root shows that they have the function to maintain vigorous nutritional transport in short distance. These cells are especially characterized by the presence of numerious outgrowths on the cell wall into the endophyte cavity. Correspondingly, there are abundant mitochondria, dictyosomes and numerious vesicles in the cytoplasm. The plasma membrane becomes tortuous along the cell wall and many secretory granules are present between the plasma membrane and cell wall in the cytoplasm amyloplasts and starch granules also occur constantly. The ultrastructure observed above indicates the fact that there is sound structural basis for the metabolic relationship between the host cells and the symbiont.     

Simultaneous occurrence of carposporophytes and tetrasporangia in Polysiphonia urceolata

Halosacciocolax lundii sp. nov., a new red alga parasitic on Rhodymenia palmata, is described from Nova Scotia.     

Dieckol from Ecklonia cava suppresses the migration and invasion of HT1080 cells by inhibiting the focal adhesion kinase pathway downstream of Rac1-ROS signaling

We have previously isolated dieckol, a nutrient polyphenol compound, from the brown alga, Ecklonia cava (Lee et al., 2010a). Dieckol shows both antitumor and antioxidant activity and thus is of special interest for the development of chemopreventive and chemotherapeutic agents against cancer. However, the mechanism by which dieckol exerts its antitumor activity is poorly understood. Here, we show that dieckol, derived from E. cava, inhibits migration and invasion of HT1080 cells by scavenging intracellular reactive oxygen species (ROS). H₂O₂ or integrin signal-mediated ROS generation increases migration and invasion of HT1080 cells, which correlates with Rac1 activation and increased expression and phosphorylation of focal adhesion kinase (FAK). Rac1 activation is required for ROS generation. Depletion of FAK by siRNA suppresses Rac1-ROS-induced cell migration and invasion. Dieckol treatment attenuated intracellular ROS levels and activation of Rac1 as well as expression and phosphorylation of FAK. Dieckol treatment also decreases complex formation of FAK-Src-p130Cas and expression of MMP2, 9, and 13. These results suggest that the Rac1-ROS-linked cascade enhances migration and invasion of HT1080 cells by inducing expression of MMPs through activation of the FAK signaling pathway, whereas dieckol downregulates FAK signaling through scavenging intracellular ROS. This finding provides new insights into the mechanisms by which dieckol is able to suppress human cancer progresssion and metastasis. Therefore, we suggest that dieckol is a potential therapeutic agent for cancer treatment.     

Phylogeny and taxonomy of the Raphidophyceae (Heterokontophyta) and Chlorinimonas sublosa gen. et sp. nov., a new marine sand-dwelling raphidophyte

A new flagellate of the Raphidophyceae, Chlorinimonas sublosa gen. et sp. nov., collected from Wakayama Prefecture, Japan is described based on morphological observations, microspectrophotometry of chloroplasts, and phylogenetic analysis of SSU rDNA sequences. The cell was usually elliptical, sometimes spherical, oval or slender, and possessed two subequal heterodynamic flagella emerging from a subapical pit. Greenish yellow discoidal chloroplasts, 15–25 per cell, were situated at the periphery of the cell. The alga is very similar to the genus Heterosigma, but distinct in that there is no invagination of thylakoids into the pyrenoids and no typical girdle lamella in the chloroplast, and the chloroplasts are greenish yellow. Phylogenetic analysis of SSU rDNA revealed that this alga forms a sister clade with the clade of Chattonella and Heterosigma. Based on these results, we propose a new genus Chlorinimonas with Chlorinimonas sublosa as the type species. In addition, this paper is the first report of molecular data covering all genera of the Raphidophyceae. The phylogenetic analysis suggests that the intrusion to freshwater habitat has occurred only once in the Raphidophyceae.     

THE MORPHOLOGY OF CUBICULOSPORUM KORONICARPIS GEN. ET SP. NOV., REPRESENTING A NEW FAMILY IN THE GIGARTINALES (RHODOPHYTA)

The red alga Cubiculosporum koronicarpis gen. et sp. nov. is described from material collected during 1968 in the Philippines. The species differs substantially in regard to its carposporophyte development from other red algae in the order Gigartinales, and a new family is created based on its unique combination of reproductive features. A single, short, connecting filament is formed between the fertilized carpogonium and a nearby auxiliary cell. The latter produces several ramifying gonimoblast filaments towards the interior of the thallus. No fusion cell is formed and the gonimoblast filaments grow inward among the cells of the central axis, form secondary connections to them, and give rise to outwardly directed carposporangial filaments that develop within peripheral chambers formed between elongating inner cortical cells. The alga is a low, clump-forming species of well-washed intertidal reef platforms at the one Philippine locality where it has been found. There it contributed a uniform but very minor amount to the wet weight of the standing crops that were studied during two separate seasons of the year.     

PHOSPHOTUNGSTIC ACID-CHROMIC ACID: A SELECTIVE STAIN FOR ALGAL PLASMA MEMBRANES1,2

A phosphotungstic acid-chromic acid mixture selectively stains the plasma membrane of whole cells of selected members of the Chlorophyceae, Charophyceae, Euglenophyceae, Xanthophyceae, Bacillariophyceae, Chrysophyceae, and Rhodophyceae, and the plasma membrane in cell-free fractions of Mougeotia (Chlorophyceae). The procedure is not effective on the plasma membrane of the cyanophycean Scytonema or the cyanophycean endosymbiont of Glaucocystis. Staining of the cell walls of Chlamydomonas, Bangia, and Scytonema and the pellicle and sliding junction of Euglena and Astasia suggest that PTA-CrO₃ reactivity may be associated with glycoproteins in the cell walls and plasma membranes.