bluuebunny/crossref_metadata_2025_split huggingface dataset:
DIURNAL FLUCTUATION OF NITRATE REDUCTASE ACTIVITY IN THE MARINE RED ALGA GRACILARIA TENUISTIPITATA (RHODOPHYTA)1
Authors: Lopes Patrícia F. , Oliveira Mariana C. , Colepicolo Pio 
Published: October 2004

ABSTRACTThe biochemical characteristics and diurnal changes in activity of the enzyme nitrate reductase (NR; EC 1.6.6.1) from the marine red alga Gracilaria tenuistipitata var. liui Zhang et Xia are described. Different assay conditions were tested to determine the stability of NR. The crude extract of G. tenuistipitata has a NR specific activity of 10.2 U.mg−1, which is higher than the NR activities found for other algae, plants, and fungi. This NR is highly active at a slightly alkaline pH and is stable over a wide range of temperature, with an optimal activity at 20° C. The apical portions of the thallus contain 64.9 ± 6.6% of the total NR specific activity. The apparent Michaelis‐Menten (Km) constant found for KNO3 was 197 μM, and it was 95 μM for NADH. The NR from G. tenuistipitata can be included in the NADH‐specific group, because no activity was found when NADPH was used as an electron donor. In extracts of algae grown under either continuously dim light or a light‐dark cycle, the activity of NR exhibits a daily rhythm, peaking at the middle of the light phase, when activity is 30‐fold higher than during the night phase.
THE CYTOSKELETON OF THE NAKED GREEN FLAGELLATE SPERMATOZOPSIS SIMILIS (CHLOROPHYTA):FLAGELLAR AND BASAL BODY DEVELOPMENTAL CYCLE1
Authors: Lechtreck Karl‐Ferdinand , Reize Ingo Botho , Melkonian Michael 
Published: October 2004

ABSTRACTFlagellar and basal body development during cell division was studied in the biflagellate green alga Spermatozopsis similis Preisig et Melkonian by light microscopy of immobilized living cells, statistical analysis of flagellar lengths during the cell cycle, and electron microscopy of cells and isolated cytoskeletons. Interphase cells display two flagella of unequal/subequal length. An eyespot located in an anterior lobe of the chloroplast is connected to the basal body bearing the shorter flagellum by means of a five‐stranded microtubular root. Until cell division, the two parental flagella attain the same length. During cell division, each cell forms two new flagella that grow to a length of 1.5 μm before they are distributed in a semiconservative fashion together with the parental flagella to the two progeny cells at cytokinesis. During the following interphase, the flagella newly formed during the preceding cell division grow to attain the same length as the parental flagella until the subsequent cell division. The shorter of the two flagella of a cell thus represents the developmentally younger flagellum, which transforms to the mature state during two consecutive cell cycles. Interphase cells display only two flagella‐bearing basal bodies; two nascent basal bodies are formed during cell division and are connected to the microtubular d‐roots of respective parental basal bodies with which the newly formed basal bodies are later distributed to the progeny cells. During segregation, basal body pairs shaft into the 11/5 o'clock direction, thus conserving the 1/7 o'clock configuration of basal body pairs of interphase cells. Prior to chloroplast and cell division, an eyespot is newly formed near the cell posterior in close association with a 1s microtubular root, while the parental eyespot is retained. During basal body segregation, eyespot‐root connections for both the old and newly formed eyespots are presumably lost, and new associations of the eyespots with the 2s roots of the newly formed basal bodies are established during cytokinesis. The significance of this “eyespot‐flagellar root developmental cycle” for the absolute orientation of the progeny cells is discussed.
PHYLOGENYOF CHLOROMONAS (CHLOROPHYCEAE): A STUDY OF 185 RIBOSOMAL RNA GENE SEQUENCES1
Authors: Buchheim Mark A. , Buchheim Julie A. , Chapman Russell L. 
Published: October 2004

ABSTRACTThe unicellular, biflagellate genus Chloromonas differs from its ally, Chlamydomonas, primarily by the absence of pyrenoids in the vegetative stage of the former. As with most green flagellate genera, little is known about phylogenetic affinities within and among Chloromonas species. Phylogenetic analyses of nuclear‐encoded small‐subunit ribosomal RNA gene sequences demonstrate that a sampling of five Chloromonas taxa, obtained from major culture collections, do not form a monophyletic group. However, only three of these isolates, Chloromonas clathrata, Chloromonas serbinowi, and Chloromonas rosae, are diagnosable morphologically as Chloromonas species by the absence of a pyrenoid in the vegetative stage. The three diagnosable Chloromonas taxa form an alliance with two pyrenoid‐bearing chlamydomonads, Chlamydomonas augustae and Chlamydomonas macrostellata. With the exception of Chloromonas serbinowi, which represents the basal lineage within the clade, each of the diagnosable Chloromonas taxa and their pyrenoidbearing Chlamydomonas allies were isolated originally from mountain soils, snow, or cold peat. These observations suggest that habitat, independent of pyrenoid status, may be most closely linked to the natural history of this clade of chlamydomonad flagellates.
INFECTIOUS DISEASES OF MAZZAELLA LAMINARIOIDES (RHODOPHYTA): CHANGES IN INFECTION PREVALENCE AND DISEASE EXPRESSION ASSOCIATED WITH SEASON, LOCALITY, AND WITHIN‐SITE LOCATION1
Authors: Corren Juan A. , Buschmann Alejandro , Retamales Claudia , Beltrán Jessica 
Published: October 2004

ABSTRACTThis study addresses the issues of infection prevalence and disease expression in two wild populations of the red algal host Mazzaella laminarioides and their variability associated with locality, season, and spatial location of the host in the intertidal zone. Our results demonstrated that Endophyton ramosum is the most frequent infective pathogen affecting M. laminarioides in Matanzas and Pucatrihue. This situation prevailed through the year and across the high‐to‐low intertidal gradient. Although there was a general trend for lower levels of infection in late winter and early spring, only in a few, cases was well‐defined seasonality detected. Furthermore, clear seasonal patterns, as displayed by deformative disease in the high intertidal zone of Pucatrihue, were attenuated in the middle and lower intertidal zones. Differences in levels of infection in M. laminarioides between the high intertidal zones of Matanzas and Pucatrihue diminished toward the low intertidal zone. Thus, effects of seasonality and locality on infection prevalence may be influenced, at least in part, by the position of the hosts an the intertidal zone.Spatial distribution of the diseased individuals also varied along the beach. This pattern was consistent between the two sites and seemed related to wave exposure and the specific pathogen. Comparisons of the size distribution of noninfected fronds with their infected counterparts showed that infections by Endophyton ramosum and Pleurocapsa sp. more frequently affected medium‐and large‐sized fronds. This pattern was consistent temporally and similar in the two localities. Finally, a clear association between maturity and prevalence of infection was detected. This association resulted in most fronds of the noninfected segment of the host population being immature, whereas most mature fronds were infected. In conclusion, infectious diseases affecting the red alga Mazzaella laminarioides are a persistent phenomenon in wild populations of the host, although only a small segment of the infected populations displays the full expression of the disease. In spite of the suggested role of factors such as season, latitude, and spatial location of the host on disease prevalence and expression, additional studies are needed to understand fully the dynamics of infectious diseases in wild populations of algal hosts.
THE EFFECT OF A HORN SNAIL ON ULVA EXPANSA (CHLOROPHYTA): CONSUMER OR FACILITATOR OF GROWTH?1
Authors: Fong Peggy , Desmond Julie S. , Zedler Joy B. 
Published: October 2004

ABSTRACTTo determine whether California horn snails are more likely to be consumers or facilitators of Ulva expansa (Setch) S. & G. growth in estuaries, we conducted manipulative experiments that evaluated algal growth and the movement of N between the water column, algal tissue, and, in the second experiment, sediments. Algae grew poorly in the absence of sediments, drawing on their own sequestered N supplies (3.5% of dry weight reduced to <2%) and N released by snails and by depleting inorganic N in the water column. There was no evidence of consumption when snail densities ranged from 0 to 900.m−2 (0, 3, 6, and 9 per aquarium), as algal growth was similar for all snail densities, and snail lengths did not increase during the 21–d experiment. when sediment was provided, N was depleted in the sediment and enhanced in the algal tissue. As in the first experiment, the water column was depleted of inorganic N and enriched with organic N, mostly in the dissolved form. Because both snails and macroalgae often dominate the shallow waters of southern California's lagoons and estuaries, our evidence that the snails are primarily facilitators of algal growth (via transfer of N from sediments to the water column) suggests that snails may play an important role in both food web and N dynamics.
STUDIES ON TRANSPARENT EXOPOLYMER PARTICLES (TEP) PRODUCED IN THE ROSS SEA (ANTARCTICA) AND BYPHAEOCYSTIS ANTARCTICA(PRYMNESIOPHYCEAE)1
Authors: Hong Ying , Smith Walker O. , White Ann‐Maree 
Published: October 2004

ABSTRACTThe distribution and production of transparent exopolymer particles (TEPs) were studied quantitatively both in cultures ofPhaeocystis antarcticaKarsten (Prymnesiophyceae) and in natural phytoplankton assemblages in the Ross Sea, Antarctica. TEP production in culture was a function of growth rate and photosynthetic activity and was strongly influenced by photon flux density. The concentrations of TEP measured during a bloom, dominated byP. antarctica,were higher than those produced by coastal diatom blooms and were correlated with chlorophyll a (Chl a), being low at Chlalevels below 3 μgL−1but increasing rapidly at greater Chlaconcentrations. Because higher chlorophyll hek are dominated 4 largerP. antarcticacolonies, this relationship suggests that TEP was produced primarily by sloughing and disintegration of the colonial matrix. TEP concentrations (both absolute and relative to Chla)increased as the bloom's biomass increased. Vertical distributions of TEP and Chlashowed TEP: chlorophyll maxima at the bottom of the water column at most stations. Because TEP and floc formation are tightly coupled, we suggest that mucous flocs derived from TEP, rather than intactP. antarcticacolonies, are the dominant component of aggregates and subsequent organic carbon vertical flux.
LIGHT‐HARVESTING COMPLEX AF'OPROTEINS IN CYTOPLASMIC VACUOLES IN CHLAMYDOMONAS REINHARDTII (CHLOROPHYTA)1
Authors: Wolfe Oregory R. , Park Hyoungshin , Sharp William P. , Hoober J. Kenneth 
Published: October 2004

ABSTRACTCells of Chlamydomonas reinhardtii Dangeard strain cw15arg7A contain electron‐opaque material, often in the form of large granules, within cytoplasmic vacuoles. Immunoelectron microscopy with antibodies to polypeptide 11, a component of the major light‐harvesting chlorophyll (Chl) a/b‐protein complex (LHCII,) of thylakoid membranes, revealed the presence of LHCII Polypeptides within the chloroplast and in vacuolar material in cells grown in the light. Vacuolar material was also heavily immunodecorated in dark‐grown cells that did not synthesize Chl. Accumulation of LHCII polypeptides was further studied in greening and light‐grown cells of a pale green mutant, deficient in LHCII, that was derived from cu15arg7A by insertional mutagenesis. Light‐grown cells of this mutant strain contained relatively few thylakoid membranes and synthesized LHCII polypeptides at a low rate. However, cytoplasmic vacuoles were immunoreactive. Appearance of mature‐sized LHCII polypeptides in vacuoles suggested that these proteins were partially translocated across the envelope but not retained by the chloroplast without assembly of LHCII.
PARASITIC INTERACTIONS AND VEGETATIVE ULTRASTRUCTURE OF CHOREOAEMA THURETII (CORALLINALES, RHODOPHYTA)1
Authors: Broadwater Sharon T. , LaPointe Elizabeth A. 
Published: October 2004

ABSTRACTThe monotypic coralline red alga, Choreonema thuretii (Bornet) Schmitz (Choreonematoideae), grows endophytically within three geniculate genera of the Corallinoideae. Although the thallus of Choreonema is reduced, lacks differentiated plastids, and is endophytic except for its conceptacles, its status as a parasite has been questioned because cellular connections to the host had not been ob served. Transmission electron microscopy, however, disclosed a previously undescribed type of parasitic interaction in which Choreonema interacts with its host through specialized cells known as lenticular cells. These small, lens‐shaped cells are produced from the single file of host‐penetrating vegetative cells. Pit plug morphology between vegetative and lenticular cells is polarized. Plug caps facing the vegetative cell have normal coralline morphology, while those facing the lenticular cell are composed of three layers. Regions of lenticular cells near host cells protrude toward the host cell; upon encountering the host cell wall, the prolrusion produces numerous finger‐like fimbriate processes that make cellular connections with the host cell. Lenticular cells may extend several protrusions toward a host cell or penetrate more than one host cell; two or more lenticular cells may also penetrate the same host cell. The lack of secondary pit connections, cell fusions, and passage of parasitic nuclei suggest that this parasitic relationship may be evolutionarily older than previously reported cases of parasitism in red algae.
SINGLE‐CELL PIGMENTATION OF PORPHYRA LINEARIS ANALYZED BY FOURIER TRANSFORM MULTI‐PIXEL SPECTROSCOPY AND IMAGE ANALYSIS1
Authors: Katz Shlomit , Dubinsky Zvy , Rothmann Chana , Malik Zvi , Friedlander Michael 
Published: October 2004

ABSTRACTThe novel method of Fourier transform multi‐pixel spectroscopy was used for the nondestructive analysis of and comparison of pigmentation in different regions of live thalli of the red alga Porphyra linearis. Because the thallus in this alga consists of a monolayer of nonoverlapping cells, we were able to analyze the pigmentation of single cells by combining light absorbance with natural fluorescence data. From the image of each cell in the vegetative male and female reproductive and holdfast regions, more than 4 ± 104 fluorescence and absorbance spectra were obtained. Specific pigments in the different regions were localized by the use of a software program of similarity mapping followed by image construction. The reconstructed images revealed subcellular localization of each pigment according to specific spectroscopic fingerprints. The results showed that the vegetative and female reproductive cell types had a significantly higher content of phycoerythrin than of phycocyanin, and quite similar chlorophyll a levels. Most of the holdfast cells were poorly pigmented, but had more chlorophyll a than phycoerythrin or phycocyanin. The male reproductive cells contained only traces of pigments. Thus, by using Fourier transform multipixel spectroscopy, we were able to characterize the pigmentation of different regions of the thallus and follow the distribution patterns of the different pigments on the subcellular level along the differentiation gradient of the alga.
DETECTION AND EVALUATION OF A NOVEL SEXUAL PHEROMONE THAT INDUCES SEXUAL CELL DMSION OF CLOSTERIUM EHRENBERGII (CHLOROPHYTA)1
Authors: Fukumoto Ryo‐hei , Fujii Tadashi , Sekimoto Hiroyuki 
Published: October 2004

ABSTRACTMating type‐plus (mt+; NIES‐228) cells of Closterium ehrenbergii undergo a division to form gamete‐shaped cells. This cell division is induced by a substance produced by mating type‐minus (mt−; NIES‐229) cells. Light and the presence of mt+ cells enhanced production of the substance. The active substance is heat labile and has an apparent molecular mass of 20 kDa. From these results, we conclude that the substance is a novel, proteinaceous sexual pheromone involved in reproduction of Closterium ehrenbergii.
FIVE NEW GOMPHONEMA SPECIES (BACILLARIOPHYCEAE) FROM RIVERS IN SOUTH AFRICA AND SWAZILAND1
Authors: Passy Sophia I. , Kociolek John P. , Lowe Rex L. 
Published: October 2004

ABSTRACTDiatom material from South Africa and Swaziland was examined with light and scanning electron microscopy. Five new taxa are proposed: Gomphonema crocodilei, G. quasicrocodilei, G. venusta, G. latistigmata, and G. cholnokyi. Gomphonema venusta has been previously misidentified as Gomphonema clevei Fricke and G. cholnokyi as G. subclavatum (Grunow) Grunow. All of the species possess biseriate striae, areolae with external vela, a true stigma, and marginal laminae underlying the valve margin and mantle. Compared to the other members of gomphonemoid lineage, the five new species show greatest similarity to Gomphoneis mesta Passy‐Tolar & Lowe, G. magna Kociolek & Stoermer, and G. rhombica (Fricke) Merino, García, Hernández‐Mariné, & Fernández and to the Herculeana lineage of Gomphoneis sensu Kociolek and Stoermer. The most recent phylogenetic analysis of the genus Gomphoneis showed that the two lineages of the genus. Herculeana and Elegans, are not monophyletic. The Herculeana lineage is more closely allied to Gomphonema than to the Elegans lineage. Since the Elegans lineage contains the generitype of Gomphoneis (G. elegans (Grunow) Cheve), and the species described here are more closely related to the Herculeana lineage, we have assigned them to Gomphonema.
CHARACTERIZATION OF SCHIZOSERIS CONDENSATA, SCHIZOSERIDEAE TRIB. NOV. (DELESSERIACEAE, RHODOPHYTA)1
Authors: Hommersand Max H. , Fredericq Suzanne 
Published: October 2004

ABSTRACTThe Myriogramme group of Kylin contains two distinct clusters of genera that merit recognition at the tribal level. We previously established the tribe Myriogrammeae, and in this paper we erect the Schizoserideae based on a study of the type species of Schizoseris, S. laciniata (=S. condensata), from the southern hemisphere. The Schizoserideae is characterized by 1) marginal and diffuse intercalary meristems; 2) nuclei initially arranged in a plate in the median plane in meristematic and mature cells; 3) chloroplasts one to few, lobed or dissected; 4) microscopic veins absent; 5) procarps scattered, formed singly on either side of the blade with cover cells absent and consisting of a one‐ to two‐celled lateral sterile group, a one‐ to two‐celled basal sterile group, and a four‐celled carpogonial branch in which the trichogyne passes beneath the lateral sterile group and emerges anterior to it; 6) auxiliary cell diploidized by a connecting cell cut off posteriolaterally from the fertilized carpogonium; 7) gonimoblast initial cut off laterally from one side of the auxiliary cell and giving rise to unilaterally branched gonimoblast filaments bearing carposporangia in branched chains; 8) gonimoblast fusion cell highly branched, candelabra‐like, incorporating all but the basalmost cells of the carposporangial chains and radiating through the central cells in the floor of the cystocarp; 9) spermatangial and tetrasporangial sori formed from surface cells in both monostromatic and polystromatic portions on both sides of the blade; and 10) tetrasporangia formed primarily from cortical rather than from central cells. The Schizoserideae presently includes Schizoseris Kylin, Neuroglossum Kützing, Abroteia J. Agardh, and Polycoryne Skottsberg in Kylin and Skottsberg.
POPULATION GENETICS AND TAXONOMY OF CAULERPA (CHLOROPHYTA) FROM THE GREAT BARRIER REEF, AUSTRALIA1
Authors: Benzie John A. H. , Price Ian R. , Ballment Elizabeth 
Published: October 2004

ABSTRACTAllozyme variation was examined in seven species and four varieties of Caulerpa sampled from the Great Barrier Reef (GBR) region, Australia. Differences between species were greater than those between populations of the same taxon sampled from different geographical locations, and typically included fixed gene differences (no alleles found in one taxon shared by the other taxon) at two or more loci. Three varieties of C. racemosa, vars imbricata, laetevirens, and racemosa, and a peltate morph of C. racemosa were as strongly distinguished genetically as the six other species examined: C. cupressoides, C. lentillifera, C. peltata, C. serrulata, C. sertularioides, and C. taxifolia. Cluster analysis did not place all of the C. racemosa varieties together and linked them with other species, but cladistic analyses showed the allozyme data gave little useful phylogenetic information. Eight of 13 plants identified initially as C. serrulata were distinguished at several loci, indicating the presence of an undetermined cryptic taxon. Population genetic analysis of polymorphism, which occurred in some taxa, demonstrated strong spatial differentiation among populations of C. cupressoides, C. racemosa vars laetevirens and racemosa, C. serrulata, and C. taxifolia and significant but variable degrees of clonality and/or inbreeding within these populations. Allozymes proved to be a useful tool for defining species boundaries and investigating population structure in Caulerpa, but not for determining phylogenetic relationships within the genus.
PHYLOGENETIC RELATIONSHIPS OF SELECTED EUGLENOID GENERA BASED ON MORPHOLOGICAL AND MOLECULAR DATA1
Authors: Montegut‐Felkner Ann E. , Triemer Richard E. 
Published: October 2004

ABSTRACTThe small subunit rRNA (SSU rRNA) coding regions sequenced from the euglenoids Petalomonas cantuscygni, Peranema trichophorum, and Khawkinea quartana were used to assess the phylogenetic relationships of these genera within the Euglenozoa. Phylogenies derived from distance, parsimony, and maximum likelihood methods infer that the euglenoids and kinetoplastids form sister clades within a monophyletic assemblage. Distances representative of closely related lineages separate the genera within the Kinetoplastida, whereas larger distance values separate genera within the euglenoid assemblage. The results of the morphological and molecular studies suggest that phagotrophy arose early in the euglenozoan lineage with the subsequent acquisition of phototrophy, osmotrophy, and parasitism. Phagotrophic euglenoids with a pellicle composed of longitudinal strips appear to have diverged prior to genera with helically arranged strips. This study suggests that the hypothetical ancestor to the Euglenozoa was a phagotroph with two flagella, both containing paraxonemal rods. Furthermore, its basal bodies contained proximal cartwheels, were connected by a prominent fiber, and were anchored with three asymmetrically arranged flagellar roots.
DIRECT ENUMERATION OF BACTERIA FROM MACROALGAE BY EPIFLUORESCENCE MICROSCOPY AS APPLIED TO THE FLESHY RED ALGAE KAPPAPHYCUS ALVAREZII AND GRACILARIA SPP. (RHODOPHYTA)1
Authors: Largo Danilo B. , Fukami Kimio , Adachi Masao , Nishijima Toshitaka 
Published: October 2004

ABSTRACTThis report describes a simplified method for direct counting of total bacteria associated with the fleshy red algae Kappaphycus alvarezii (Doty) Doty and Gracilaria spp. A Nuclepore® polycarbonate membrane (0.2–μm pore size) fitted to a vacuum filtration apparatus was used to filter algal tissue homogenate after serial dilution and staining with the fluorochrome 4′,6‐diamidino‐2‐phenylindole. Using epifluorescence microscopy, it is possible to count bacteria without preseparating them from the algae. The technique requires homogenized algal tissue diluted with 0.2‐μm‐filtered, autoclaved seawater to a level appropriate for counting. Dilution reduces the amount of autofluorescent algal debris, which may interfere with Counting. The membrane filtration method yielded a bacterial count two orders of magnitude higher than that of the conventional agarspread plate technique. This method offers a more accurate approach to counting the total number of bacteria on macroalgae.