ENTRY OF A CHLORELLA-VIRUS INTO ITS HOST CELL1

The endosymbiotic Chlorella sp. (Chlorophyceae) of Paramecium bursaria (Ciliata) can be infected by a double-stranded DNA-containing virus (Chlorella-virus) that has a phagelike entry mechanism. Electron micrographs show that soon after attachment of the virus to the algal cell wall, a hole is formed through which the viral DNA enters the alga. Biochemical studies on a European Chlorella-virus system suggest that digestion of the algal cell wall is caused by glycolytic enzymes, one of which was identified as a β-d -glucosidase. Enzymes are bound to the virus capsid and are activated only after or by the attachment of the virus to its cognate alga or to preparations of the algal cell wall. Common features of viral cell wall-digesting enzymes and algal autolysins are discussed.     

A PROBLEMATIC FILAMENTOUS SAPROPHYTIC ALGA

Singh , R. N. (Banaras Hindu U., Varanasi 5, India.) A problematic filamentous saprophytic alga. Amer. Jour. Bot. 49 (2) : 188–191. Illus. 1962.—A problematic, filamentous and saprophytic alga, having superficial resemblance to a water-mold, is described. Although some of its features, such as highly vacuolated colorless protoplast, non-cellulosic cell wall, and peg-like outgrowths from the filaments, show fungal affinities, it has been considered to be a saprophytic alga. Its characteristic setiferous branches of large cells, sporangia with recurved sterigmata and, at times, its heterotrichy show affinities with Trentepohlia.     

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.     

Bromine, Bromophenols and Floridorubin in the Red Alga Lenormandia prolifera

The pigment floridorunin was localized to the cuticle of the red alga Lenormandia prolifera (C. Ag.) J. Agardh by x-ray micro-analysis in Ihe transmission electron microscope and by its colour reactions in the light microscope. The pigment was set free from the cell wall by a pectinase. Bromine was also identified in the chloro-plasts. the middle lamellae, the intercellulars and the pore plugs of the alga. The content of bromophenols in the alga increases with increasing age. The cell walls of old plants are stratified and their outer parts are apparently shed. The bromophenols could have a function as regulators of the epiphytes or the shedding of parts of the outer cell wall.     

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.     

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.     

ULTRASTRUCTURE OF THE LICHEN COENOGONIUM INTERPLEXUM NYL.

Coenogonium interplexum Nyl. is a green to yellow-orange filamentous lichen commonly found on tree bark, rocks, and soil. The mycobiont is the ascomycetous fungus Coenogonium. The ultrastructure of the lichenized phycobiont, Trentepohlia, closely resembles that of the non-lichenized form, a filamentous subaerial green alga. The mycobiont has a typical fungal ultrastructure, and the cell wall sometimes appears thinner at points of contact with the phycobiont wall. Several branched fungal hyphae are usually randomly arranged around a Trentepohlia filament, and may in some cases completely ensheath the alga. Although no haustoria were observed, this relationship may still be termed a lichen since there is some modification of the alga and the lichen is structurally distinct from the two symbionts.     

A temperature-conditional protoplast of Chlamydomonas reinhardi

A mutant of the green alga Chlamydomonas reinhardi has been isolated which forms a cell wall at 25 °C but not at 35 °C. This conditional protoplast might be of interest in all studies where the temporary presence or absence of the cell wall is desired.     

Colchicine-induced expansion ofVaucheria cell apex. Alteration from isotropic to transversally anisotropic growth

The tip-growth ofVaucheria geminata was analyzed. The elemental rate of surface expansion (RERE) at the very apex of this alga cell reaches ca. 100% min⁻¹. The expansion is almost isotropic; i.e. the both meridional and latitudinal components of RERE are almost equal. An antimicrotubular reagent, colchicine, caused expansion at the actively growing cell apex of this alga. This drug did not change the surface expansion rate, but altered the polarity of cell wall expansion from isotropic to transversally anisotropic. The orientation of cell wall microfibrils is random at the apex but axial at the basal cylindrical part of the cell. Colchicine did not change the fluence-response relationship for the first positive phototropism.     

CHEMICAL COMPOSITION OF THE CELL WALLS OF THE FRESHWATER RED ALGA LEMANEA ANNULATA (BATRACHOSPERMALES)1

Cell walls of the generic phase of the freshwater red alga Lemanea annulata Kütz were mechanically isolated and chemically characterized. Walls consisted mainly of polysaccharide with lesser quantities of associated protein and lipid. The major wall component was alkali-soluble xylan, comprised mainly of 4-linked β-xylopyranosyl residues and small amounts of 3-O-substituted β-xylopyranosyl residues. Hot water extracts yielded non-sulfated polymers, with 3- or 3,4-linked β-galactosyl residues alternating with 4-linked α-glucuronosyl residues as the predominant structural features. This acid polysaccharide shares many characteristics of the mucilage previously described from the freshwater genus Batrachospermum. Isolated cell walls of L. annulata contained approximately 6% cellulose. Cellobiohydrolase/colloidal gold labelling of cell walls revealed β-4-glycan throughout the fibrillar portion of the wall. Wall protein consisted of at least 17 amino acids, of which threonine and alanine were the most abundant. Polysaccharides of the cell walls of L. annulata differ from those of marine red algae and are similar to those described for other Batrachospermales.     

MERCURY ACCUMULATION IN PEDIASTRUM BORYANUM (CHLOROPHYCEAE)1,2,3

Laboratory grown cultures of the green alga Pediastrum boryanum (Turp.) Meneg. concentrate mercury in amounts greater than the concentration in the culture medium. The concentration effect proceeds rapidly during colony formation and is directly dependent upon the materials of the outer layer of the cell wall known to include silica and sporopollenin. The alga displays exceptional tolerance to the rather high levels of mercury used.     

Characterization of a green alga isolated from infected human external tissue

A green alga was isolated from infected external human tissue. The alga consisted of spherical non‐flagellate unicells, 3–13 µm in diameter, surrounded by a thick outer wall of variable thickness and containing a single bowl‐shaped chloroplast without a pyrenoid. Asexual reproduction occurred through multiple autospores produced within the parental cell wall. 18S rRNA and 16S rRNA gene‐sequence analyses indicated that the alga was closely related to ‘Chlorella’saccharophila. d ‐glucose considerably enhanced both phototrophic and heterotrophic growth. Compared with two other strains of ‘C.’saccharophila, the organism in the present study grew more rapidly at temperatures greater than 30°C in darkness, but it could not grow at 37°C in light or darkness. The results suggest that this strain may not normally invade tissues, but becomes established and grows on previously infected tissues of external body extremities where the temperature is somewhat lower than normal body temperature.     

ULTRASTRUCTURE OF THE CORALLINACEAE (RHODOPHYTA) II. VEGETATIVE CELLS OF LITHOTHRIX ASPERGILLUM1

The ultrastructure of the calcareous red coralline alga Lithothrix aspergillum Gray and the development of the various tissue types has been studied. The sub-apical meristematic tissue alternately produces genicular or intergenicular cells. The genicular cells rapidly elongate and their cell walls thicken and become denser as more fibrillar wall material is laid down within the cell wall. These cells contain little cytoplasm and few organelles. The inter genicular cells which elongate only slightly during development have a small vacuole and many free starch grains in the cytoplasm. The peripheral cells in each inter genicular layer remain meristematic and form a cortical cell layer over the genicular cells. These cortical cells and the apical meristematic cells are covered by small epidermal cells which have extensive cell wall ingrowths between the chloroplasts. The inter genicular cells are calcified. Although the CaCO₃ is laid down within the cell walls, there is always a thin layer of CaCO₃-free organic cell wall material between the plasmalemma and the CaCO₃ impregnated wall. Only the distal tips of the genicular cells are calcified. In old genicular tissues of Lithothrix, secondary deposits of CaCO₃ of unknown crystallography are also found in the spaces between the cell walls. Thus there appear to be at least two mechanisms of calcification in this alga.     

A thermodynamic study of Cu++−Zn++ ion exchange in theNitella flexilis cell wall

Summary Exchange isotherms of Cu²⁺ vs Zn²⁺-ions were performed on the cell wall of a fresh water alga,Nitella flexilis. The relevant thermodynamic parameters are calculated. The cell wall absorbs copper selectively. The selectivity is explained by a stronger chelation of the cupric ion, due to the Jahn-Teller effect. The wall acts like a two-site model, based on the nature of the ligands: a first group of aminesites reacts exothermically and a second of hydroxylic-carboxylic sites of lower affinity, reacts endothermically.     

Variations of the Surface Sculpture and Cell Wall Ultrastructure of the Zygospores in Chlamydomonas geitleri (Chlorophyta)

The superficial cell wall ornamentation in the zygospores of the alga Chlamydomonas geitleri Ettl (Chlorophyta) is formed by thickenings of the cell wall which are shaped into a network of anastomosing ribs, sometimes with local wart-like protuberances. Clearly different sculpture patterns (given by presence, arrangement and/or morphological modification of sculpture elements) were accompanied by many transient forms. Sculpture variations occurred even in clonal cultures. In the zygospore cell wall of C. geitleri, the inner, outer and middle layer can be distinguished from the morphological point of view. The relatively thin outer (sporopollenin) layer covers the whole surface of the zygospore wall. The thicker inner layer adhering to the zygospore protoplast forms, either solely or together with the middle layer (possessing a fine meshwork substructure), variously shaped thickening of the zygospore cell wall. Discussed are the ultrastructural morphology of the cell wall in Chlamydomonas zygospores, the striking similarity of the cell wall ultrastructure of zygospores in C. geitleri to the ultrastructure of the cell wall of vegetative cells in some green algae (subfamily Scotiellocystoideae), as well as the extensive morphological variability of the zygospore wall sculpture in C geitleri and its species specificity.     

<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.     

The ultrastructure of the marine blue green alga,Trichodesmium erythraeum,with special reference to the cell wall,gas vacuoles,and cylindrical bodies

Summary The marine blue green alga, Trichodesmium erythraeum, was studied with electron microscopy in an attempt to elucidate the structural basis for its rapid lysis when removed from its marine environment. In this connection, it was found that a thining of the electron-dense layer of the longitudinal wall at the site adjacent to transverse wall attachment was responsible for lysis. The underlying biochemical basis for this change has not been elucidated because of the extreme difficulties of maintaining and growing the alga in culture under defined conditions. Several other features of considerable interest also were found. Especially interesting is the very regular array of gas vacuoles in the form of a hollow cylinder which shields most of the photosynthetic system. It was suggested that the gas vacuoles might possibly function optically, having adaptive value in protecting the free-floating alga from excessive radiation. In addition, a detailed structure of the cylindrical bodies was presented, and its structure with the photosynthetic lamellae was compared. On the basis of sectoring to form fragments of double lamellar units from the cylindrical body which are identical in structure to the photosynthetic lamellae, it has been postulated that the cylindrical body may be the site of synthesis for the photosynthetic system in Trichodesmium erythraeum.     

On the morphology and ultrastructure of the cell wall of Spirulina platensis

The cell wall of the blue-green alga Spirulina platensis was studied with the electron microscope using ultra-thin sectioning, shadowing, carbon-replication or freeze-etching techniques for specimen preparation. The cell wall could be resolved into four layers, L-I through L-IV. The L-I and L-III layers contain fibrillar material. The septum is a three-layered wall: an L-II layer sandwiched between L-I layers. The shape in vitro of isolated septa might be an artifact due to the preparation technique used. Certain structural properties of the septum seem to allow tangential stretching; they might be reflected in the flexible gliding mobility of Spirulina species. The outer, L-IV layer contains material longitudinally arranged along the trichome axis.     

HEMIFLAGELLOCHLORIS KAZAKHSTANICA GEN. ET SP. NOV.: A NEW COCCOID GREEN ALGA WITH FLAGELLA OF CONSIDERABLY UNEQUAL LENGTHS FROM A SALINE IRRIGATION LAND IN KAZAKHSTAN (CHLOROPHYCEAE,CHLOROPHYTA)1

A coccoid green alga, Hemiflagellochloris kazakhstanica S. Watanabe, S. Tsujimura, T. Misono, S. Nakamura et H. Inoue, gen. et sp. nov., was described from soil samples of a saline irrigation land in Ili River basin, Kazakhstan. This alga had a parietal chloroplast with a pyrenoid, which was covered with starch segments and penetrated with thylakoid membranes. Reproduction occurred by the formation of aplanospores and zoospores. The aplanospores frequently formed tetrad aggregations in a mother cell. The zoospores were covered by a single‐layered cell wall and lacked stigmata. The zoospores had two flagella of considerably unequal lengths; the longer flagellum was 17–19 lm in length and the shorter one was 9–10 lm. The flagellar apparatus architecture was of the clockwise orientation group type in the Chlorophyceae. Molecular phylogenetic analysis using 18S and 28S rDNA sequence data resolved this organism in a separate clade from the green algae that had flagella of slightly unequal lengths. It was suggested that features such as inequality in flagellar lengths, parallel exsertion of basal bodies, and subapical position of the flagellar apparatus were sporadically evolved.     

Proteins from the lichenXanthoria parietina which bind to phycobiont cell walls. Correlation between binding patterns and cell wall cytochemistry

Summary A protein fraction was isolated from the lichenXanthoria parietina which bound to the appropriate cultured phycobiont, but not to the freshly isolated symbiotic alga. The protein also appeared to discriminate between five other strains of cultured phycobionts from different lichens; phycobionts isolated from lichens in the familyTeloschistaceae bound the protein whereas phycobionts isolated from lichens in other families did not. Using cytochemical techniques, it was shown that protein binding ability was correlated with high levels of acidic polysaccharide in the cell wall, and the presence of a protein coat on the cell wall surface of the phycobiont. The possible role of this protein in recognition between lichen symbionts is briefly discussed.