bluuebunny/crossref_metadata_2025_split huggingface dataset:
IMMUNOLOCALIZATION OF CENTER IN THE FLAGELLAR APPARATUS OF MALE GAMETES OF ECTOCARPUS SILICULOSUS (PHAEOPHYCEAE) AND OTHER BROWN ALGAL MOTILE CELLS1
Authors: Katsaros Christos I. , Maier Ingo , Melkonian Michael 
Published: October 2004

ABSTRACTCentrin or a centrin homologue was localized using immunofluorescence in the flagellar basal body region in zoids of five brown algal species: Ectocarpus siliculosus (Dillw.) Lyngb., Scytosiphon lomentaria (Lyngb.) Link, Laminaria digitata (Huds.) Lamour., Sphacelaria rigidula (Kütz.) Prud'homme van Reine, and Fucus serratus L. The antigen is restricted to short rods extending along the basal body(ies) and towards the nucleus, which always remains firmly linked to the flagellar apparatus in isolated cytoskeletons. To identify these antigenic sites, pre‐ and postembedding immunogold electron microscopy was applied to male gametes of E. siliculosus. At least three different structures associated with the basal bodies were antigenic: a fibrous structure connecting the proximal end of the posterior basal body to the nucleus (nucleus‐basal body connector), a striated band that links the two basal bodies to each other and is located in the angel formed by them, and amorphous material interconnecting the basal bodies in their most proximal regions. In addiction, specific labeling occurs along the external surface and within the lumen of both basal bodies and in the flagellar transitional region. The possible function of these centrin‐containing structures is discussed.
OBSERVATIONS ON LICHENIZED AND FREE‐LIVING PHYSOLINUM (CHLOROPHYTA, TRENTEPOHLIACEAE)1
Authors: Davis Joseph S. , Rands David G. 
Published: October 2004

ABSTRACTLichenized Physolinum Printz and free‐living Physolinum from a dimly lit cave were studied from fresh collections and cultures, preserved specimens fixed in situ, and cultures that had persisted for 5 years in an environmental chamber. The branched filamentous association consists of a phycobiont and a characteristic ascomycetous mycobiont of one layer that completely ensheathes the algal partner. Epiphytic blue‐green algae commonly occur attached to the mycobiont. The phycobiont, Physolinum monilia (De Wildem.) Printz, produces thick‐walled, green spiny cells, some of which enlarge and contact the sheathing mycobiont cells; the phycobiont and mycobiont may then develop into new lichenized filaments. The hyaline mycobiont cells extend haustoria bound by the fungus wall deeply into the phycobiont chloroplasts. The epiphytes, Synechocystis‐like colonies, are firmly attached to the outer walls of the mycobiont and are associated with several‐celled extensions of the fungus beyond the apical phycobiont cells. Free‐living Physolinum monilia filaments are branched and moniliform; the search‐containing uninucleate cells are spherical to pyriform and have walls of cellulose. Each cell has a single massive chloroplast with plastoglobuli among tightly packed thylakoids. Except for their larger cells, P. monilia filaments appear to be identical to the phycobiont of lichenized Physolinum.
ULTRASTRUCTURE OF THE BASAL APPARATUS AND PUTATIVE VESTIGIAL FEEDING APPARATUSES IN A QUADRIFLAGELLATE EUGLENOID (EUGLENOPHYTA)1
Authors: Triemer Richard E. , Lewandowski Carole L. 
Published: October 2004

ABSTRACTThe flagellar apparatus and presumptive vestigial feeding apparatuses of a cold‐water, photosynthetic, quadriflagellate euglenoid is described. The organism possesses two similar sets of flagella each consisting of one short and one long flagellum. Each pair of flagella is associated with three microtubular roots for a total of six roots in the basal apparatus. At the level of the ventral basal bodies, each intermediate root is nine‐membered, while the ventral roots are composed of eight to nine microtubules. Only one of the ventral roots lines the single microtubule reinforced pocket. A four‐membered dorsal root attaches to each dorsal basal body, and at the level of the reservoir each gives rise to a dorsal band. An additional bundle of microtubules, not arising from the microtubular roots of the basal apparatus, begins posterior to the basal apparatus as a small group of a few microtubules and extends anteriorly on the right ventral side of the reservoir ending at the canal. At the level of the stigma, the microtubules are organized into a multi‐layered bundle that continues to increase in size and eventually splits to form two bundles at the level of the canal. We postulate that these bundles may represent the remnants of a rod‐and‐vane‐type feeding apparatus like that found in many phagotrophic euglenoids.
PROTEINACEOUS AND IMMUNOCHEMICAL DISTINCTIONS BETWEEN THE OVAL AND FUSIFORM MORPHOTYPES OF PHAEODACTYLUM TRICORNUTUM (BACILLARIOPHYCEAE)1
Authors: Gutenbrunner Sabine A. , Thalhamer Joseph , Schmid Anna‐Maria M. 
Published: October 2004

ABSTRACTTwo morphotypes, fusiform and oval, were isolated from a single clone of the diatom Phaeodactylum tricornutum Bohlin and maintained as subclones by culturing in liquid and solid substrates, respectively. Salinity of the medium, from brackish to marine, had no effect on expression of the phenotypes. The oval cell is generated endogenously within a “transformed”fusiform cell upon transfer from liquid medium to agar plates. With the light microscope, normal and “transformed”fusiform cells, prior to giving rise to oval cells, can be discriminated by means of their staining response to toluidine blue.Sodium dodecyl sulfate‐polyacrylamide gel electrophoresis of protein extracts from lysed cells revealed slight differences in polypeptide composition between fusiform and oval types. A phenotype‐restoration experiment from oval to fusiform demonstrated that the oval type readily reestablished not only fusiform morphology but also the protein pattern characteristic for the fusiform type. Immunochemical analyses (western blots) using antisera raised against whole and lysed cells of both morphotypes revealed antigenic alterations of the oval morphotype. Several antigenic determinants restricted mainly to the surface of oval cells were detected. Results indicate that environmentally induced phenotypes of Phaeodactylum may be not only the consequence of specific gene expression but also the result of significant, general post‐translational modifications.
MEIOSIS, BLADE DEVELOPMENT, AND SEX DETERMINATION INPORPHYRA PURPUREA(RHODOPHYTA)1
Authors: Mitman Grant G. , van der Meer John P. 
Published: October 2004

ABSTRACTThe discovery in the early 1980s that meiosis occurs during germination of conchospores ofPorphyra yezoensisUeda suggested that the sexually divided fronds ofPorphyra purpurea(Roth) C. Agardh might similarly originate from meiotic segregation of a pair of sex‐determining alleles during early sporeling development. After establishing conditions suitable for propagatingP. purpureain culture, observations on developing sporelings demonstrated that meiosis takes place during the first two divisions of the germinating conchospores. In the first division, the spore is split into an upper and lower cell. In the second, an anticlinal division in the upper cell yields two daughter cells situated one beside the other, and a periclinal division in the bottom cell gives two cells arranged one above the other. Thus, during normal development, the first four cells of the sporeling constitute a meiotic tetrad whose cells are arranged in a characteristic fashion. Stable color mutants ofP. purpureawere isolated, genetically characterized, and used as genetic markers to follow the fate of individual cells of the tetrad during subsequent frond development. Nearly the entire blade of the mature thallus is derived from the two upper cells of the tetrad, with the two lower cells mostly giving rise to the rhizoidal holdfast region. Cell lineage boundaries laid down by the segregation of color alleles at meiosis corresponded perfectly with those later defined by sexual differentiation on the same fronds, strongly supporting the hypothesis that sex determination inP. purpureais controlled by alleles at a segregating chromosomal locus.
PHYSIOLOGICAL ECOTYPES IN THE MARINE ALGA BOSTRYCHIA RADICANS (CERAMIALES, RHODOPHYTA) FROM THE EAST COAST OF THE U.S.A1
Authors: Karsten Ulf , West John A. , Zuccarello Giuseppe , Kirst Gunter O. 
Published: October 2004

ABSTRACTThe comparative ecophysiology of nine culture isolates of the eulittoral red alga Bostrychia radicans (Montagne) Montague collected at sites from seven states along the east coast of the U.S.A. was investigated. The growth response in relation to different salinity and light conditions as well as photosynthesis‐irradiance curves were studied. In addition, the effect of salt treatment on the content of the isomeric polyols d‐sorbitol and d‐dulcitol was also studied. All isolates grew between salinities of 5.3 and 70 ppt but with quite different optima and maxima. The isolates were all adapted to low light levels, i.e. growth was already recorded at 2.5 μmol photons·m−2·s−1, and growth rates peaked between 40 and 60 μmol photons·m−2·s‐1. These low‐light requirements were also reflected by the photosynthesis‐irradiance curves: all plants had low light compensation points (2.5–9.7 μmol photons ·m−2·−1) and low photon fluence rates for initial saturation of photosynthesis (38.1–84.7 μmol photons·m−2·s−1, indicating that these isolates are “shade‐adapted.” Isolates from Florida and Georgia synthesized and accumulated both the osmolytes d‐sorbitol and d‐dulcitol in increasing salinities, whereas only d‐sorbitol was present in plants from North Carolina north to Connecticut. d‐sorbitol was always strongly involved in osmotic acclimation. In various isolates from the same location in South Carolina, both polyol patterns were found, i.e. d‐sorbitol plus d‐dulcitol and d‐sorbitol only. All data indicate that B. radicans exhibits a broad salinity tolerance and a low‐light preference, which explain the successful colonization of this alga on various intertidal and shaded substrates. The data also clearly indicate intraspecific differences among the nine isolates, which is interpreted as development of different physiological ecotypes.
ORGANIC CARBON RELEASE BYDUNALIELLA SALINA(CHLOROPHYTA) UNDER DIFFERENT GROWTH CONDITIONS OF CO2, NITROGEN, AND SALINITY1
Authors: Giordano Mario , Davis Joseph S. , Bowes George 
Published: October 2004

ABSTRACTTwo strains ofDunaliella salina(Dunal) Teod., UTEX 1644 and UTEX 200, were cultured under different growth regimes, including 10 mM NO3−or NH4+, 1.5 or 3.0 M NaCl, and low (0.035%) or high (5%) CO2in air. The release of14C‐labeled dissolved organic carbon (DOC), expressed as a rate and as a percentage of photosynthetic14CO2assimilation, was subsequently determined. The percentage of DOC released was inversely related to cell density in the assay medium, but photosynthesis on a per‐cell basis was not. Release of DOC was low, in the range of 1–5% of photosynthesis, but during acclimation to growth on NH4+, it rose to 11%. The presence of NH4+rather than NO3−in the growth medium increased therateof release by both strains, but thepercentagerelease was stimulated only in UTEX 200 cells, because their photosynthetic rate was depressed by NH4+. For UTEX 1644, high, as compared to low, CO2‐grown cells, had somewhat higher rates and percentages of DOC release, but release from UTEX 200 cells was unaffected by the growth‐CO2. The rate of DOC release by high CO2‐grown cells was not enhanced at a low concentration of dissolved inorganic carbon, indicating that the released material did not originate from the photorespiratory pathway. The effects of NaCl on DOC release varied with strain and growth conditions. For UTEX 200, the cells in NO3−, but not NH4+, exhibited a doubling or more in percentage of release with a doubling in NaCl concentration, irrespective of growth‐CO2. With UTEX 1644 the low CO2‐grown cells showed the greatest enhancement in 3.0 M NaCl. Organic matter accumulated on the external surface of the cell membrane and constituted a well‐defined cell‐coat, which was more dense in NH4+than in NO3−‐grown cells. Microtubules, which may play a role in maintaining cell shape, were observed just below the plasma membrane.From a practical viewpoint, the presence of organic material in the hypersaline ponds of salt‐works is detrimental to salt production. WhenD. salinacells become abundant in such ponds, the attendant, continuous release of DOC may make a significant contribution to the problem.
LIGHT AND ELECTRON MICROSCOPIC CHARACTERIZATION OF TWO TYPES OF PYRENOIDS INGONIUM(GONIACEAE, CHLOROPHYTA)1
Authors: Nozaki Hisayoshi , Kuroiwa Haruko , Kuroiwa Tsuneyoshi 
Published: October 2004

ABSTRACTThe single, basal pyrenoids ofGonium quadratumPringsheim ex Nozaki andG. pectoraleMüller (Goniaceae, Chlorophyta) differed in appearance when vegetative colonies were cultured photoheterotrophically in medium containing sodium acetate. Chloroplasts ofG. quadratumhad distinct pyrenoids when grown in medium without major carbon compounds. However, the pyrenoids degenerated and were markedly reduced in size when such cells were inoculated into a medium containing 400 mg·L−1of sodium acetate. No pyrenoids were visible under the light microscope; however, with electron microscopy small pyrenoids and electron‐dense bodies were visible within the degenerating chloroplasts, which had only single layers of thylakoid lamellae at the periphery. The chloroplasts subsequently developed distinct pyrenoids and several layers of thylakoid lamellae as the culture aged. In contrast, vegetative cells ofG. pectoralealways showed distinct pyrenoids when cells were inoculated into medium containing sodium acetate, sodium pyruvic acid, sodium lactate, and/or yeast extract. Therefore, we propose two terms, “unstable pyrenoids” and “stable pyrenoids,” for pyrenoids ofG. quadratumandG. pectorale, respectively. Chloroplasts of the colonial green flagellates should thus be examined under various culture conditions in order to determine whether their pyrenoids are unstable or stable when pyrenoids are used as taxonomic indicators. Immunogold electron microscopy showed that the ratios of gold particle density of ribulose‐1,5‐biphosphate carboxylase/oxygenase (RuBisCO) between pyrenoid matrix and chloroplast stroma inG. quadratumgrown in medium with or without sodium acetate were lower than those ofG. pectorale.Heavy labeling by anti‐RuBisCO was observed in both the electron‐dense bodies and pyrenoid matrix ofG. quadratum.This is the first electron microscopic demonstration of degeneration and development of both pyrenoids and thylakoid lamellae in the chloroplast as a function of culture condition in green algae.
SYSTEMATIC SIGNIFICANCE OF THE ABSENCE OF PIT‐PLUG CAP MEMBRANES IN THE BATRACHOSPERMALES (RHODOPHYTA)1
Authors: Pueschel Curt M. 
Published: October 2004

ABSTRACTFour species of the Batrachospermales were examined by transmission electron microscopy to determine whether or not cap membranes, a typical structural component of pit plugs in several orders of red algae, were present. Routine specimen preservation methods used in past studies led to contradictory reports, soBatrachospermum keratophytumBory,B. sirodotiiSkuja ex Reis,Sirodotia suecicaKylin, andS. tenuissima(Collins) Skuja ex Flint were prepared by secondary fixation in potassium permanganate or a combination of potassium ferrocyanide‐osmium tetroxide to enhance membrane contrast. These fixation procedures produced clear, well‐contrasted images in which cap membranes were absent. The absence of cap membranes inS. suecicaandS. tenuissimaand the presence of cap membranes in two members of the Nemaliales was confirmed by freeze‐substitution methods. Absence of cap membranes in representatives of the Batrachospermales further distinguishes the Batrachospermales from the Nemaliales, the order in which they long resided, and demonstrates the value of this character in elucidating ordinal alliances among the Rhodophyta.
PHYLOGENETIC RELATIONSHIPS WITHIN THE COLONIAL VOLVOCALES (CHLOROPHYTA) INFERRED FROM CLADISTIC ANALYSIS BASED ON MORPHOLOGICAL DATA1
Authors: Nozaki Hisayoshi , Itoh Motomi 
Published: October 2004

ABSTRACTA cladistic analysis was used to deduce the phylogenetic relationships within the colonial Volvocales. Forty‐one pairs of characters related to gross morphology and ultrastructure of vegetative colonies as well as asexual and sexual reproduction were analyzed based on parsimony, using the PAUP 3.0 computer program, for 25 species belonging to nine volvocacean and goniacean genera of the colonial Volvocales.Chlamydomonas reinhardtiiDangeard was the outgroup. The strict consensus tree indicated the presence of two monophyletic groups, one composed of all the volvocacean species analyzed in this study and the other containing the goniacean species except for the four‐celled speciesGonium sociale(Dujardin) Warming. In addition, these two groups constitute a large monophyletic group, to whichG. socialeis a sister group. A new combinationTetrabaena socialis(Dujardin) Nozaki et Itoh and a new family Tetrabaenaceae Nozaki et Itoh are thus proposed forG. sociale.In addition, the analysis suggests that the volvocacean generaEudorinaandPleodorinaare paraphyletic groups, respectively, and that the monotypic genusYamagishiellahas no autapomorphic characters and represents primitive features of the anisogamous and oogamous genera of the Volvocaceae. Phylogenetic relationships within the Volvocaceae and the Goniaceae, as well as the various modes of sexual reproduction exhibited by these organisms, are discussed on the basis of the analysis.
IMMUNOLOCALIZATION OF CENTRIN IN OXYRRHIS MARINA (DINOPHYCEAE)1
Authors: Höhfeld Ingo , Beech Peter L. , Melkonian Michael 
Published: October 2004

ABSTRACTA new polyclonal antibody was raised against centrin isolated from the flagellate green alga Spermatozopsis similis (Chlorophyta; anti‐SSC). It stains by immunofluorescence and immunoelectron microscopy well‐known reference systems for centrin like the nucleus–basal body connectors in Chlamydomonas reinhardtii (Chlorophyta) and the system II fibers (rhizoplasts) of Scherffelia dubia (Chlorophyta). In addition, it recognizes in immunoblots a single 20‐kDa protein in isolated cytoskeletons of Spermatozopsis similis and Tetraselmis striata (Chlorophyta) as well as purified centrin isolated from Tetraselmis striata. Using this antibody, centrin was localized in whole cells and isolated cytoskeletons of Oxyrrhis marina Dujardin (Dinophyceae) by immunofluorescence and immunogold electron microscopy. In the flagellar apparatus of O. marina, five different structures were antigenic. Four short fibers (connectives 1–4) link the basal bodies to the four major fibrous flagellar roots, which do not cross‐react with anti‐centrin. The most prominent of the labeled structures (connective 5), a crescent‐shaped fiber, extends from the flagellar canal of the transverse flagellum along the base of the tentacle to the flagellar canal of the longitudinal flagellum, interconnecting the distal parts of the microtubular roots/bands in the basal apparatus. For most of its length, it underlies and is connected to a transversely oriented subamphiesmal microtubular band. In immunoblot analyses, anti‐SSC recognizes only a single 20‐kDa protein in cytoskeletons of O. marina. Functional and phylogenetic aspects of centrin‐containing structures in dinoflagellates are discussed.
ASSESSING THE RELATIONSHIPS OF SOME COCCOID GREEN LICHEN ALGAE AND THE MICROTHAMNIALES (CHLOROPHYTA) WITH 18S RIBOSOMAL RNA GENE SEQUENCE COMPARISONS1
Authors: Friedl Thomas , Zeltner Cornelia 
Published: October 2004

ABSTRACTEight complete nuclear‐encoded small‐subunit ribosomal RNA (18S rRNA) gene sequences were determined for four genera of the Microthamniales (Pleurastrophyceae) and forGloeotilopsis planctonicaIyengar & Philipose (Ulvophyceae, Ulotrichales) to investigate evolutionary relationships within the Microthamniales and the taxonomic position of this order within the green algae. Phylogenies inferred from these data revealed specific relationships at the level of genera and species that disagree with those inferred from vegetative cell morphology but agree with those inferred from motile cell characters. The rRNA phylogenies provide even better resolution than that gained from morphology alone. The coccoid lichen algaTrebouxiaspp. is specifically related to other coccoid lichen and soil algae (i.e.Myrmecia biatorellaeBoye‐Petersen andFriedmannia israelensisChantanachat & Bold), forming the “Lichen Algae Group,” an evolutionarily distinct lineage within the Microthamniales.Trebouxiais a paraphyletic andPleurastruma polyphyletic genus in rRNA phylogenies. In contrast to previous hypotheses based on morphology,Pleurastrum terrestreFritsch & John is not closely related toTrebouxiabut occupies an isolated position within the Microthamniales. The filamentous algaMicrothamnion kuetzingianumis not ancestral to coccoid members of the Microthamniales but is closely related with the coccoidFusochloris perforata(Lee & Bold) Floyd, Watanabe & Deason. The Microthamniales are inferred to be an array of independent lineages that radiate nearly simultaneously and may also include some autosporic coccoid taxa previously classified in the Chlorophyceae. Monophyly of the Microthamniales could not be demonstrated unequivocally. In contrast to a hypothesis based on ultrastructure, the Microthamniales are evolutionarily distinct from the Ulotrichales. The latter are ancestral to the radiation of the Microthamniales and the Chlorophyceae in the rRNA phylogenies.
VARIABILITY OF NITRATE UPTAKE CAPACITY IN MACROCYSTIS PYRIFERA (LAMINARIALES, PHAEOPHYTA) WITH NITRATE AND LIGHT AVAILABILITY1
Authors: Kopczak Charles D. 
Published: October 2004

ABSTRACTThe nitrate uptake capacity of mature blade tissue of the giant kelp, Macrocystis pyrifera (L.) C. Ag., was examined as a function of the availability of light and nitrate. Time course measurements indicated that nitrate uptake rate, as measured by the incorporation of 15N, was significantly increased by N starvation. The response was linear over the first hour of exposure regardless of the N status of the tissue indicating that surge uptake was not responsible for the increase. The Michaelis‐Menten parameters Vmax and Ks, however, were not significantly changed by either growth nitrate concentration or growth irradiance as a result of high variability among blades. Similarly, the initial slope (α) of the nitrate uptake kinetics curves was unaffected. Concentration of photosynthetic pigments increased in response to increased nitrate availability but not to increased growth irradiance. Time course and pigment data demonstrated that mature blade tissue responds to increased N availability by decreasing its capacity to take up nitrate and by increasing its investment in photosynthetic pigments, perhaps for N storage or enhanced light‐harvesting capabilities and the increase in reducing power available for N assimilation. This study provides evidence for a dynamic regulatory system that responds to changes in nitrate availability in an integrated manner.