bluuebunny/crossref_metadata_2025_split huggingface dataset:
OPTICAL PROPERTIES OF DENSE ALGAL CULTURES OUTDOORS AND THEIR APPLICATION TO REMOTE ESTIMATION OF BIOMASS AND PIGMENT CONCENTRATION IN SPIRULINA PLATENSIS (CYANOBACTERIA)1
Authors: Gitelson Anatoly A. , Laorawat Supat , Keydan Galya P. , Vonshak Avigad 
Published: October 2004

ABSTRACT Reflectance and vertical attenuation coefficient spectra from 400 to 1100 nm were investigated in detail on dense algal cultures of Spirulina in order to create algorithms for remote estimation of pigment and biomass concentration. Reflectance and the vertical attenuation coefficients were compared with biomass and pigment concentration in outdoor algal cultures. For assessing biomass concentration, the sum of reflectance above the base line from 670 to 950 nm was used. This allows the estimation of biomass with an error of less than 0.06 g·L−1 For chlorophyll a and phycocyanin estimation, vertical attenuation coefficients at the wavelengths 440 nm (or 676 nm) and 624 nm, respectively, were employed. The developed algorithms were tested by using independent data sets in the range of chlorophyll a from 0.2 to 20mg·L−1 and biomass from 0.15 to 1.1 g·L−1. An error of pigment estimation of less than 0.80 mg·L−1 was achieved. The potential use of the algorithms in algal biotechnology is further discussed.
BRIEF INCUBATION OF GAMETANGIA‐BEARING CAPS IN ANTIBIOTICS ELIMINATES BRANCHING IN PROGENY OF ACETABULARIA ACETABULUM (CHLOROPHYTA)1
Authors: Mandoli Dina F. , Wexler Adam , Teschmacher Jill , Zukowski Annette 
Published: October 2004

ABSTRACT Branching of the stalk of Acetabularia acetabulum L. (Silva) was investigated by inbreeding and by a brief treatment of gametangia with a variety of antibiotics. The position of the branch along the stalk varied, implying that branching was not restricted to any one time in development (base is oldest and apex is youngest). The branching phenotype was not inherited in Mendelian fashion. Although three microscopic structures (“bubbles,”“pustules,” and “scars”) occurred on the stalks of cells that had branched, these structures were not statistically correlated with branching in the population (n=699 cells). However, brief treatment of gametangia with a new antibiotic mixture did eliminate all macro‐ and microscopic structures associated with branching of the stalk in the subsequent generation. We could not fulfill Koch's postulates or provide clear evidence for the pathogenic nature of cell branching. Our brief antibiotic treatment of gametangaa of Acetabularia acetabulum was rapid, had no adverse effects, and virtually eliminated branching (and any potential pathogens) from laboratory cultures in the subsequent generations. Our method allows biochemical and molecular analyses to proceed uncomplicated by the possible presence of other organisms and provides a clean baseline for the future selection of mutations that may induce heritable branching.
GROWTH OF HETEROSIGMA CARTERAE (RAPHIDOPHYCEAE) ON NITRATE AND AMMONIUM AT THREE PHOTON FLUX DENSITIES: EVIDENCE FOR N STRESS IN NITRATE‐GROWING CELLS
Authors: Wood Gareth J. , Flynn Kevin J. 
Published: October 2004

ABSTRACT The marine alga Heterosigma carterae Hulburt (Raphidophyta) was grown in N‐limiting batch cultures using either nitrate or ammonium as the N source, at photon flux densities (PFDs) of 50, 200, and 350 μmol·m‐2·s‐1 in a 12:12 h LD cycle. Carbon content could be estimated from biovolume (μg C = 0.278 × nL; R =0.98) but not reliably from pigment content. During exponential growth, ammonium‐grown cells (in comparison with nitrate‐grown cells at the same PFD) attained higher growth rates by at least 20%, contained more N, and had a lower C:N ratio, higher concentrations of intracellular free amino acids, and higher ratios of glutamine: glutamate (Gln: Glu) and asparagine: aspartate (Asn:Asp). Growth was nearly light‐saturated on ammonium at 200 μmol·m‐2·s‐1 (cell‐specific growth rate of 1.2 d‐1) but probably not saturated in nitrate‐grown cells at 350 μmol·m‐2·s‐1. PFD did not affect Gln: Glu or Asn: Asp for a given N source. These results indicate that the nitrate‐growing cells were more N‐stressed than those using ammonium (which in contrast were relatively C‐stressed) and that this organism would show an enhanced competitive advantage against other species when supplied with a transient supply of ammonium rather than nitrate.
SEASONAL VARIATIONS OF PHOTOSYNTHETIC PIGMENTS, TOTAL C, N, AND P CONTENT, AND PHOTOSYNTHESIS IN PHYLLARIOPSIS PURPURASCENS: (PHAEOPHYTA) FROM THE STRAIT OF GIBRALTAR
Authors: Flores‐Moya Antonio , Fernández José A. , Xavier Niell F. 
Published: October 2004

ABSTRACT Photosynthetic pigments, C, N, and P tissue composition, and photosynthetic rate were measured from April to October in the brown alga Phyllariopsis purpurascens (C. Agardh) Henry et South (Laminariales, Phaeophyta) growing at a 30‐m depth in the Strait of Gibraltar. Ir‐radiance reaching the population ranged from 13.5 to 27.5 mol.m‐2.mo‐1. The available light for this species, expressed as a percentage of the irradiance above the water, was 1.8%. Dissolved inorganic nitrogen forms, NO3‐and NH4+, were constant from April to October, whereas phosphate was depleted in August. Chlorophyll a decreased from 520.0 ± 165.0 to 199.6 ± 159.9 μg.g‐1 dry weight; in contrast, chlorophyll c and carotenoids did not change until September but increased threefold in October. C:N and N:P ratios changed in the same way and in the same range. They were constant until July but increased from 15–17 up to 42 (C:N) and from 14 to 40 (N:P) in October, suggesting a severe P limitation of growth of this species. The dark respiration rate and the light compensation point were constant from April to October (0.5 ± 0.1 μmol O2. m‐2.s‐1 and 6.5 ± 0.2 μmol.m‐2. s‐1, respectively), whereas the maximum rate of apparent photosynthesis, light onset saturation parameter, and half saturation constant for light were maximum in April to May (3.7 μmol O2. m‐2.s‐1and 40 and 41.5 μmol.m‐2. s‐1, respectively) and October (3.6 μmol O2. m‐2.s‐1 and 50 and 53.7 μmol.m‐2. s‐1, respectively). They were minimum in August (1.2 μmol O2.m‐2.s‐1 and 11.3 and 12 μmol.m‐2.s‐1, respectively). These minimum figures yielded a negative carbon budget in August and 0 in September, whereas it was positive the rest of the year. Photosynthetic efficiency, estimated by the ratio between maximum apparent photosynthesis and light half saturation constant, showed a strong agreement with productivity measured by means of an independent method. These results indicate that lamina expansion in this species is controlled by photosynthetic efficiency.
CYTOCHROME f LOSS IN ASTAXANTHIN‐ACCUMULATING RED CELLS OF HAEMATOCOCCUS PLUVIALIS (CHLOROPHYCEAE): COMPARISON OF PHOTOSYNTHETIC ACTIVITY, PHOTOSYNTHETIC ENZYMES, AND THYLAKOID MEMBRANE POLYPEPTIDES IN RED AND GREEN CELLS
Authors: Tan Shi , Cunningham Francis X. , Youmans Michelle , Grabowski Beatrice , Sun Zairen , Gantt Elisabeth 
Published: October 2004

ABSTRACT Photosynthetic activity, chloroplast enzymes, and poly‐peptides were compared in green and red (ketocarotenoid‐containing) cultures of the microalga Haematococcus pluvialis Flotow. Green cultures, grown at 80 μmol pho‐tons.m‐2. s‐1 in an acetate‐containing medium, had a mean generation time of 27 h. Ketocarotenoid accumulation was induced by transfer of green cultures to PO4‐deficient medium and exposure to 250 μmol photons.m‐2. s‐1. Under these conditions, there was no increase in cell number, and the cultures turned red. Relative amounts of enzymes and thylakoid polypeptides in red and green cells were ascertained by immunoprobing with standardization on a chlorophyll (Chl) basis. In red cultures, the level of cytochrome f was greatly decreased (< 1% of green cell level), which is expected to greatly impair the linear electron flow from photosystem (PS) II to PS I. Also, the levels of apoproteins in red cells, namely, of CPI, D2, CP47, LHC I, and ribulose‐1, 5‐bisphosphate carboxylase were reduced to 15, 18, 29, 48, and 80%, respectively, of those in green cells. Only adenosine triphosphate syn‐thase exhibited no significant change in the two types of cultures. The respiration rate of red cultures was much higher (100 μmoles O2. mg Chl‐1.h‐1) than that of green cells (16 μmoles O2. mg Chl‐1.h‐1). Conversely, net O2 evolution (at Pmax in green cultures was 80 μmoles O2. mg Chl‐1.h‐1 but was —40 μmoles O2. mg Chl‐1.h‐1 in red cultures. PS II activity was demonstrated in broken cells of both green and red cultures, showing activity of 40 and 15 μmoles DCPIP‐mg Chl‐1.h‐1 (with DPC as electron donor), respectively. In contrast, PS I activity measured by the Mehler reaction showed that red rather than green cells had a greater activity (64 vs. 46 μmoles O2. mg Chl‐1.h‐1, respectively). Thus, in spite of the decline of O2 evolution in red cells, the photosystems were still functional. We postulate that the decline of O2, evolution in red cells is largely attributable to an increase in the respiration rate and the impairment of linear electron flow from PS II to PS I and, to some extent, to a decrease in components of the photosystems.
MORPHOLOGICAL AND BIOCHEMICAL VARIABILITY OF THE TOXIC DINOFLAGELLATE PROROCENTRUM LIMA ISOLATED FROM THREE LOCATIONS AT HERON ISLAND, AUSTRALIA
Authors: Morton Steve L. , Tindall Donald R. 
Published: October 2004

ABSTRACT Seventeen clones of the toxic, epiphytic‐benthic dinoflagellate Prorocentrum lima (Ehrenberg) Dodge isolated from three separate sites on the reef flats of Heron Island, Australia, were acclimated under the same set of environmental conditions. Morphological features examined for each clone included cell surface configuration, size, and dry weight. Physiological and biochemical features determined for each clone included reproduction rates, pigments (chlorophyll a, chlorophyll c2, peridinin, and other xanthophylls), toxins (okadaic acid and methyl‐okadaic acid), and macromolecular compounds (total protein, lipid, and carbohydrate). Variation in morphological features and reproduction rates of clones within and between sites was minimal and not significant. Also, variation in biochemical features within an individual site was low, but pronounced differences existed among sites, the most notable of which was toxin content (okadaic acid and methyl‐okadaic acid). The greatest difference in biochemical features was between clones isolated from the southern site and clones isolated from the northern and southeastern sites. Results of a cluster analysis of clonal characters support the view that these two groups represent distinct genotypes. We suggest that these groups originated from separate seed sources and that the genetic integrity of each is maintained through asexual reproduction.
EFFECT OF DISSOLVED OXYGEN PARTIAL PRESSURE ON THE ACCUMULATION OF ASTAXANTHIN IN CHEMOSTAT CULTURES OF HAEMATOCOCCUS LACUSTRIS (CHLOROPHYTA)
Authors: Lee Yuan‐Kun , Ding Sun‐Yeun 
Published: October 2004

ABSTRACT The effect of dissolved oxygen partial pressure on the accumulation of astaxanthin in the green alga Haematococcus lacustris (Gir.) Rostaf (UTEX16) was studied in N‐limited continuous chemostat cultures. The steady‐state astaxanthin content measured against culture volume, cell number, and biomass dry weigh of Haematococcus cultures was proportional to the dissolved O2 partial pressure in the culture medium, over the range of 0–50% O2 The steady‐state biomass dry weight concentrations remained at between 0.52 and 0.57 g. L‐1 over the range of dissolved O2 partial pressure studied. Steady‐state cell densities at dissolved O2 partial pressures above the air saturation level (1.13–1.58 × 105 cells.mL‐1) were about half of that measured at lower dissolved O2 partial pressures (2.42–2.63 × 105 cells.mL‐1). Both biflagellated zoospores and nonmotile aplanospores were found at steady state. The fraction of nonmotile cells was higher at dissolved O2 partial pressures above the air saturation level (94.44–98.01%) than at dissolved O2 partial pressure below the air level (79.64–86.12 and 91.75%).
SUGAR‐CONTAINING COMPOUNDS ON THE CELL SURFACES OF MARINE DIATOMS MEASURED USING CONCANAVALIN A AND FLOW CYTOMETRY
Authors: Waite Anya M. , Olson Robert J. , Dam Hans G. , Passow Uta 
Published: October 2004

ABSTRACT Some diatom exudates may remain attached to the exterior cell surface, potentially altering cell stickiness and affecting important aspects of the diatom's ecology such as aggregation rates and grazing rates. We measured the accumulation of cell‐surface sugar‐containing compounds by labeling cultured marine diatoms with fluorescent‐tagged sugar‐binding lectins and measuring the fluorescence associated with each cell using flow cytometry. The binding of FITC‐labeled concanavalin A (FITC‐ConA), a lectin that binds to glucose and mannose residues, varied 5‐fold among different diatom species in exponential growth (on a per‐cell basis) and 2–3‐fold within a given species in different physiological states. Although transparent exopolymer particles followed a simple accumulation curve over time in batch culture, FITC‐ConA. cell‐1 did not follow the same pattern, suggesting that surface sugar accumulation is not driven simply by the accumulation of such particles in the medium. For Thalassiosira pseudonana (Hustedt) Hasle and Heimdal (3H clone), the amount of sugar‐containing compounds on the cell surface increased transiently as growth rate slowed in early stationary phase under both N and Si limitation. For Chaetoceros neogracile (Schuett) van Landingham, FITC‐ConA. cell‐1had a strong inverse relationship with growth rate across several Si‐limited batch culture experiments. Both results suggest some biological mediation of cell‐surface sugar‐containing compounds. Our study reveals the great potential for using lectin binding to investigate cell‐surface sugars on diatoms. Lectins allow us to investigate noninvasively the role of cell‐surface sugar‐containing compounds in modifying cell stickiness and aggregation, as well as the partitioning of exuded phytoplankton carbon. We suggest that cell‐surface sugar accumulation may be related to diatom stickiness, based on a correlation between our FITC‐ConA measurements and stickiness estimates in the literature on several of the species we studied.
REGULATION OF GROWTH PROCESSES DURING THE CELL CYCLE OF THE CHLOROCOCCAL ALGA SCENEDESMUS QUADRICAUDA UNDER A DNA REPLICATION BLOCK
Authors: Zachleder Vilém 
Published: October 2004

ABSTRACT The kinetics of two growth parameters (total RNA and total protein accumulation) was followed in synchronized cultures of the chlorococcal alga Scenedesmus quadricauda (Turp.) Bréb. under conditions of inhibited DNA replication in the presence of 5‐fluorodeoxyuridine (25 mg.L‐1). In the control culture, growth processes occurred in several steps with a decreasing rate of accumulation of RNA and protein amount approximately at each doubled value of the preceding step. Oscillations in the rate of growth processes in the control culture were temporally related to the initiation of individual reproductive steps. At each doubling, the cell became committed to triggering a sequence of reproductive processes, starting with DNA replication and ending with protoplast fission. Three commitment points were attained in the control culture and, consequently, three replication rounds of DNA followed by three nuclear divisions and three protoplast fissions occurred during one cell cycle. If 5‐fluorodeoxyuridine (FdUrd) was added at the beginning of the cell cycle, no reproductive processes occurred, and the cells remained uninuclear with one genome and did not divide. RNA accumulation did not seem to be affected by the presence of FdUrd for at least one cell cycle, and three or four doublings in the amount of RNA occurred during this period. Protein accumulation was even more independent of reproductive processes in the cell and continued for a period of about two or three cell cycles, attaining six doublings at the end of this period. Therefore, oscillations in the rate of protein or RNA accumulation remained even if reproductive processes were inhibited.
GENERAL ULTRASTRUCTURE AND FLAGELLAR APPARATUS ARCHITECTURE OF WOLOSZYNSKIA LIMNETICA (DINOPHYCEAE)
Authors: Roberts Keith R. , Hansen Gert , Taylor F. J. R. 
Published: October 2004

ABSTRACT The ultrastructure of Woloszynskia limnetica Bursa was examined using serial thin section electron microscopy. Sections of W. limnetica reveal numerous chloroplast profiles without any obvious pyrenoids. The extensive pusular complex consists of a “smooth” part and a part lined with electron‐dense particles. The nucleus is located in the episome. A stigma (=eyespot) consisting of numerous electron‐dense globules is situated beneath the amphiesmal vesicles of the sulcal groove. The longitudinal microtu‐bular root extends between the stigma and the amphiesma vesicles. Subthecal fibers occur in conjunction with the microtubules and the stigma. Both flagellar exit apertures are encircled by a broad striated collar, each giving rise to a fiber that extends along the pusular canal opening. The striated collars are interconnected by the ventral ridge fiber. The basal part of the transverse flagellum has, in addition to the normal paraxonemal rod (=striated strand or fiber), a semicircular structure consisting of fibrils. The flagellar apparatus is complex but possesses components typically found in the Dinophyceae. The longitudinal mi‐crotubular root is broad and is connected to both striated collars. The transverse basal body gives rise to the transverse microtubular root, which in turn is associated with microtubules that extend to the interior of the cell and with the transverse striated root. The transitional region of both basal bodies possesses a distinctive fibrous ring attached to each microtubular triplet by short fibers that collectively appear as spokes of a wheel. Not unexpectedly, the flagellar apparatus of Woloszynskia limnetica is much like that of the related Woloszynskia sp.; however, some dif ferences were discovered. A phylogenetic relationship between Woloszynskia limnetica, W. coronata (Wolosz.) Thompson, and W. sp. is indicated based on similarities in pusule and stigma structure.
SYNCHRONIZATION OF CHLOROPLAST DIVISION IN THE ULTRAMICROALGA CYANIDIOSCHYZON MEROLAE (RHODOPHYTA) BY TREATMENT WITH LIGHT AND APHIDICOLIN
Authors: Terui Sachiko , Suzuki Kuninori , Takahashi Hidenori , Itoh Ryuuichi , Kuroiwa Tsuneyoshi 
Published: October 2004

ABSTRACT A system of highly synchronized chloroplast divisions was developed in the unicellular red alga Cyanidioschyzon merolae De Luca, Taddei, & Varano. Chloroplast divisions were examined by epifluorescence microscopy following treatments with light and inhibitors. When the cells during stationary phase were transferred into a new medium under a 12:12 h LD cycle, chloroplasts, mitochondria, and cell nuclei divided synchronously in that order soon after the initiation of dark periods. More than 40% of the cells contained dividing chloroplasts. To obtain a system of highly synchronized cell division and chloroplast division, the cells synchronized by a 12:12 h LD cycle were treated with various inhibitors. Nocodazole and propyzamide did not affect cell and organelle divisions, whereas aphidicolin markedly inhibited cell‐nuclear divisions and cytokinesis and induced a delay in chloroplast division. More than 80% of the cells contained dividing chloroplasts when cells synchronized by light were treated with aphidicolin for 12 h. This synchronized system will be useful for studies of the molecular and cellular mechanisms of organelle divisions.
PHYLOGENETIC RELATIONSHIPS WITHIN THE COLONIAL VOLVOCALES (CHLOROPHYTA) INFERRED FROM rbcL GENE SEQUENCE DATA
Authors: Nozaki Hisayoshi , Itoh Motomi , Sano Ryosuke , Uchida Hidenobu , Watanabe Makoto M. , Kuroiwa Tsuneyoshi 
Published: October 2004

ABSTRACT The chloroplast‐encoded large subunit of the ribulose‐1, 5‐bisphosphate carboxylase / oxygenase (rbcL) gene was sequenced from 20 species of the colonial Volvocales (the Volvacaceae, Goniaceae, and Tetrabaenaceae) in order to elucidate phylogenetic relationships within the colonial Volvocales. Eleven hundred twenty‐eight base pairs in the coding regions of the (rbcL) gene were analyzed by the neighbor‐joining (NJ) method using three kinds of distance estimations, as well as by the maximum parsimony (MP) method. A large group comprising all the anisogamous and oogamous volvocacean species was resolved in the MP tree as well as in the NJ trees based on overall and synonymous substitutions. In all the trees constructed, Basichlamys and Tetrabaena (Tetrabaenaceae) constituted a very robust phylogenetic group. Although not supported by high bootstrap values, the MP tree and the NJ tree based on nonsynonymous substitutions indicated that the Tetrabaenaceae is the sister group to the large group comprising the Volvocaceae and the Goniaceae. In addition, the present analysis strongly suggested that Pandorina and Astrephomene are monophyletic genera whereas Eudorina is nonmonophyletic. These results are essentially consistent with the results of the recent cladistic analyses of morphological data. However, the monophyly of the Volvocaceae previously supported by four morphological synapomorphies is found only in the NJ tree based on nonsynonymous substitutions (with very low bootstrap values). The genus Volvox was clearly resolved as a polyphyletic group with V. rousseletii Pocock separated from other species of Volvox in the rbcL gene comparisons, although this genus represents a monophyletic group in the previous morphological analyses. Furthermore, none of the rbcL gene trees supported the monophyly of the Goniaceae; Astrephomene was placed in various phylogenetic positions.