bluuebunny/crossref_metadata_2025_split huggingface dataset:
THE FLAGELLAR APPARATUS OF CHRYSOCHROMULINA SP. (PRYMNESIOPHYCEAE)1
Authors: Birkhead Monica , Pienaar Richard N. 
Published: October 2004

ABSTRACT The flagellar apparatus of an undescribed species of Chrysochromulina Lackey that bears “eyelash” scales is reconstructed. The transitional region consists of two transitional plates each with an axosome, with no stellate pattern between them. Fine osmiophilic rings lie between the flagellar membrane and the outer doublets in the transitional region. The two jagella and the haptonema are inserted in a subapical depression that is lined ventrally by a spine‐like projection formed by one of the parietal chloroplasts. The angles of insertion are similar to those of some other Chrysochromulina species in that both the haptonema and the right basal body lie at an extreme angle to the left basal body. The connectives of the apparatus consist of a striated distal band with a dorsal extension to the R1 and a ventral extension overlying the R2, a striated distal accessory band, an auxiliary connective from the right basal body to the adjacent ventral chloroplast, a well‐developed intermediate band, two striated proximal bands, and a striated proximal accessory band. Of the microtubular roots in this Chrysochromulina species, three are associated with the left side of the cell (an R1 of 8+3; a small crystalline compound root, the R1C, associated with the R1; an R2 of three micro‐tubules), and two are associated with the right basal body (an R3 of 2/2 microtubules with which the single‐stranded R4 converges to form a 2/2+1 and then a 2/3 tiered arrangement). Comparisons are drawn with other species in the genus and related genera, particularly Prymne‐sium.
A REVISION OF THE SYSTEMATICS OF THE NIZYMENIACEAE (GIGARTINALES, RHODOPHYTA) BASED ON POLYSACCHARIDES, ANATOMY, AND NUCLEOTIDE SEQUENCES1
Authors: Chiovitti Anthony , Kraft Gerald T. , Saunders Gary W. , Liao Ming‐Long , Bacic Antony 
Published: October 2004

ABSTRACT The Australian endemic family Nizymeniaceae, based on Nizymenia australis Sonder, consists of three species in the two genera Nizymenia (1 sp.) and Stenocladia (2 spp.). We have reassessed the generic composition of the family based on evidence from nonfibrillar wall polysaccharides, vegetative anatomy, and the nucleotide sequences of an internal transcribed spacer, ITS 2, of the nuclear ribosomal cistron. Investigation of the polysaccharides by constituent sugar analysis, sulfate content determination, and methylation analysis, combined with gas chromatography‐mass spectrometry and infrared analysis, showed that the polysaccharides elaborated by the three species were branched, highly sulfated xylogalactans. These polysaccharides also contained significant amounts of mono‐O‐methyl galactose (5–8 mol% of total sugars), mainly 4‐O‐methyl galactose. Although no discrete chemical structures could be assigned to the polysaccharides, the analyses showed that those from Nizymenia australis and Stenocladia australis (Sonder) Silva were more alike than either was to that from S. furcata (Harvey) J. Agardh. This polysaccharide affinity was echoed by a suite of vegetative anatomical features. However, the only likely synapomorphy was the presence of refractive, thick‐walled medullary rhizines in both N. australis and S. australis. The ITS 2 sequences were inferred from direct sequencing of the products of polymerase chain reaction amplification. Comparison of the ITS 2 sequences of its three species with those of two outgroups indicated that the family Nizymeniaceae is monophyletic but that interspecific relationships within the family could not be resolved. We conclude that there is insufficient evidence to separate any of the species from the rest at the genus level. Therefore, all three species are consolidated into the genus Nizymenia. This necessitates nomenclatural changes of Stenocladia australis to Nizymenia conferta (Harvey) Chiovitti, Saunders, et Kraft comb. nov.
PROTOPLAST FUSION AND GENETIC COMPLEMENTATION OF PIGMENT MUTATIONS IN THE RED MICROALGAPORPHYRZDZUMSP.1
Authors: Sivan Alex , Thomas Jean‐Claude , Dubacq Jean‐Paul , Moppes Dorit van , Arad Shoshana (Malis) 
Published: October 2004

ABSTRACTProtoplasts from two green pigment mutants ofPorphyridiumsp. (UTEX 637) containing a low phycoerythrin level were fused by exposure to polyethylene glycol (MW 6000) combined with a short heat shock (45° C, 5 min). Following regeneration on agar plates, red colonies arose in which complementation of the phycoerythrin deficiency had occurred. The complementation frequency was estimated to be 0.2%. Eight progeny showing red pigmentation were isolated and purified by consecutive transfers on agar plates. Characterization of the fusion progeny revealed that their phycobiliprotein and chlorophyll contents per cell were higher than those of their parental mutant strains and, in most strains, similar to that of the wild type. The fusion products proved to be stable over many growth cycles. The DNA content of the wild type and of the parental mutant strains was about 0.05 pg‐cell−1. Fusion progeny strains showed a variable DNA content: a few fusants contained the same amount of DNA as the wild type and the parental strains, while others had about 50% more DNA per cell. The DNA content of one of the progeny strains (CF1c) was double that of the wild type (0.1 pg. cell−1). Cells of this fusion progeny contained one nucleus per cell, which suggests that nuclear fusion and the formation of a stable diploid followed cell fusion. Analysis of phycobilisome components of CF1c revealed complementation of linker polypeptides associated with phycoerythrin (γ subunits). CF1c contained, like the wild‐type strain, four linker polypeptides; all of these were absent in one parental strain and one was absent in the second. To the best of our knowledge, this is the first report of protoplast fusion, formation of somatic hybrids, and the apparent completion of a parasexual cycle in a red microalga.
CROSSING EXPERIMENTS, LIPID COMPOSITION, AND THE SPECIES CONCEPT IN ECTOCARPUS SILICULOSUS AND E. FASCICULATUS (PHAEOPHYCEAE, ECTOCARPALES)1
Authors: Muller Dieter G. , Eichenberger Waldemar 
Published: October 2004

ABSTRACT Sporophytes of Ectocarpus siliculosus (Dillwyn) Lyngbye and E. fasciculatus Harvey were collected in the vicinity of Roscoff Brittany, France. Gametophytes derived from meiospores were used for intra‐ and interspecific crosses. Intraspecific gamete combinations gave viable zygotes, which developed into fertile sporophytes. Interspecific crosses were unsuccessful. Gamete fusions did not occur between female gametes of E. fasciculatus and male gametes of E. siliculosus. Hybrid zygotes were formed in the reciprocal combination but died soon after germination. We conclude that the two species of Ectocarpus at Roscoff represent distinct taxonomic entities, which are separated by pre‐ and postzygotic compatibility barriers. These biological findings are confirmed by the differential occurrence of the chemotaxonomic marker betaine‐lipid diacetylglycerylhydroxymethyltrimethyl‐β‐alanine, which is present in our cultures of E. fasciculatus but absent in E. siliculosus.
A FIELD‐COMPATIBLE METHOD FOR EXTRACTION OF FINGERPRINT‐QUALITY DNA FROM MACROCYSTIS PYRIFERA (PHAEOPHYCEAE)1
Authors: Coyer James A. , Steller Diana L. , Alberte Randall S. 
Published: October 2004

ABSTRACT A method for extracting DNA from laminarialean algae resulting in DNA of sufficient quantity and purity for DNA fingerprints is presented. The method both eliminates the use of liquid N2 and delays the use of toxic chemicals in the initial extraction steps; thus, it is appropriate for use in remote field locations. The algal samples were ground in a solution of hexadecyltrimethylammonium bromide (CTAB) and polyvinylpyrrolidone (PVPP) at room temperature and then stored for 1 week in the CTAB‐PVPP solution at room temperature before extraction with chloroform‐isoamyl alcohol and purification by cesium chloride ultracentrifugation. No degradation of DNA was observed. Hybridization of RsaI‐digested Macrocystis pyrifera (L.) C. Ag. DNA with the M13repeat probe yielded a DNA fingerprint with 12 discrete bands 4–19 kb in molecular size.
GROWTH OF ANTARCTIC CYANOBACTERIA UNDER ULTRAVIOLET RADIATION: UVA COUNTERACTS UVB INHIBITION1
Authors: Quesada Antonio , Mouget Jean‐Luc , Vincent Warwick F. 
Published: October 2004

ABSTRACT A mat‐forming cyanobacterium (Phormidium mur‐rayi West and West) isolated from an ice‐shelf pond in Antarctica was grown under white light combined with a range of UVA and UVB irradiances. The 4‐day growth rate decreased under increasing ultraviolet (UV) radiation, with a ninefold greater response to UVB relative to UVA. In vivo absorbance spectra showed that UVA and to a greater extent UVB caused a decrease in phycocyanin/ chlorophyll a and an increase in carotenoids/chlorophyll a. The phycocyanin/chlorophyll a ratio was closely and positively correlated to the UVB‐inhibited growth rate. Under fixed spectral gradients of UV radiation, the growth inhibition effect was dominated by UVB. However, at specific UVB irradiances the inhibition of growth depended on the ratio of UVB to UVA, and growth rates increased linearly with increasing UVA. These results are consistent with the view that UVB inhibition represents the balance between damage and repair processes that are each controlled by separate wavebands. They also underscore the need to consider UV spectral balance in laboratory and field assays of UVB toxicity.
VARIABILITY OF THE HEPATOTOXIN MICROCYSTIN‐LR IN HYPEREUTROPHIC DRINKING WATER LAKES1
Authors: Kotak Brian G. , Lam Angeline K‐Y. , Prepas Ellie E. , Kenefick Sandra L. , Hrudey Steve E. 
Published: October 2004

ABSTRACT The patterns of occurrence of the peptide hepatotoxin microcystin‐LR (MC‐LR) was studied in three hypereu‐trophic hardwater lakes (Coal, Driedmeat, and Little Beaver) in central Alberta, Canada, over three open‐water seasons. MC‐LR concentration was based on high‐performance liquid chromatography detection and expressed as μg.g−1 of total plankton biomass, ng.L−1 of lake water, and μg.g−1 of Microcystis aeruginosa Kuetz. emend. Elenkin. MC‐LR was highly variable temporally (differences up to 3 orders of magnitude) within each lake over an individual year, between years in an individual lake, and between lakes in any year. Seasonal (within‐year) changes in MC‐LR concentration (expressed in the preceding units) were positively correlated to the abundance and biomass Of the cyanobacterium M. aeruginosa (r =0.60–0.77), total and total dissolved phosphorus concentration (r =0.46–0.59), pH (r=0.38–0.58), and chlorophyll a (r=0.25–0.59). Surprisingly, there was no relationship between MC‐LR concentration and water temperature (range: 7°‐24°C, r =‐0.13 to 0.02) and a negative correlation with nitrate concentration (r =–0.27 to ‐0.34). In two synoptic surveys examining spatial variability, MC‐LR concentrations were quite variable (CV of 185 and 36% between sampling sites for Coal and Little Beaver lakes, respectively). Spatial distribution of MC‐LR on any one day was correlated with the abundance and biomass of M. aeruginosa. Over a 24‐h period, MC‐LR concentration in M. aeruginosa decreased more than 6‐fold at night relative to daytime concentrations. In general, analytical and within‐site variation of MC‐LR was relatively small (CV < 4 and 9%, respectively) but greatest both within and between years in a lake followed by diel and spatial variation.
EFFECTS OF WATER VELOCITY ON THE ARCHITECTURE AND EPIPHYTES OF CLADOPHORA GLOMERATA (CHLOROPHYTA)1
Authors: Bergey Elizabeth A. , Boettiger Charlotte A. , Resh Vincent H. 
Published: October 2004

ABSTRACT The architecture of the filamentous green alga Cladophora glomerata (L.) Kütz. and the composition of this alga's epiphytes [primarily the diatoms Epithemia turgida (Ehrenb.) Kütz., Epithemia sorex Kütz., and Cocconeis pediculus Ehrenb.] were examined in different velocity regimes. After transferring algal‐bearing cobbles among velocities, the effects of changes in velocity were also examined. Cladophora branching pattern did not initially differ among slow, medium, and fast velocities, indicating that stable water velocities did not affect branching pattern. Two weeks after cobble transfer, Cladophora in fast velocity had fragmented more (i.e. had fewer filaments and fewer branch points per length of filament and had a higher percentage of unbranched filaments) than Cladophora in slow velocity. Fragmentation was greatest in tufts moved from slow velocity, suggesting velocity‐associated differences in susceptibility to breakage. Epiphytic assemblage composition differed among slow, medium, and fast velocities and between locations on the filament (base and apex). Cocconeis pediculus dominated where exposure to high velocity was greater (filament apices in medium and fast velocities), whereas the Epithemia spp. dominated where lower velocities occurred (filament bases in all velocities and apices in slow velocity). Two weeks after the cobble transfer, the translocated diatom assemblages had changed and the original pattern of diatom distribution was restored.
LIPID BIOMARKER DIVERSITY IN THE COCCOLITHOPHORIDEMILIANIA HUXLEYI(PRYMNESIOPHYCEAE) AND THE RELATED SPECIESGEPHYROCAPSA OCEANICA1
Authors: Conte Maureen H. , Thompson Anthony , Eglinton Geoffrey , Green John C. 
Published: October 2004

ABSTRACTTwenty‐four strains ofEmiliania huxleyiand two strains ofGephyrocapsa oceanicawere grown at 15°C under identical culture conditions to assess genetic variability in key lipid biomarker profiles (C37‐C39alkenones, C36and C37alkyl alkenoates, and C31‐C38alkenes). Under our culture conditions, little divergence an biomarker composition was detected betweenE. huxleyistrains from different oceanic regions or betweenE. huxleyiandG. oceanicaeven though the strains originated from biogeographical regions as diverse as the subpolar North Atlantic and subtropical Western Pacific. The major differences observed were in tetraunsaturated alkenone abundance and alkene profiles, which tended to separate neritic from open ocean strains. Different strains from the same locality were as different as strains originating from widely separated ocean basins, indicating extreme genotypic diversity within a population. Replicate cultures of the same strain showed significant variability in their biomarker profiles even though the culture temperature varied by only ±0.3°C, indicating that their synthesis ratios are influenced by environmental and/or physiological variable(s), as yet unidentified, in addition to temperature. Strong covariance in C37and C38methyl alkenone unsaturation ratios (Uk37and Uk38Mρrespectively) and, in coastal strains, C33, alkene and alkenone unsaturation ratios indicates that these compounds are biochemically linked.
MONITORING ULTRAVIOLET‐B‐INDUCED DNA DAMAGE IN INDIVIDUAL DIATOM CELLS BY IMMUNOFLUORESCENT THYMINE DIMER DETECTION1
Authors: Buma Anita G. J. , van Hannen Erik J. , Roza Len , Veldhuis Marcel J. W. , Gieskes Winfried W. C. 
Published: October 2004

ABSTRACT We developed a method to investigate the effect of ultraviolet‐B radiation (UVBR) on the formation of thy‐mine dimers in microalgal DNA that can be used for both laboratory and in situ research. Antibody labeling of dimers was followed by a secondary antibody (fluorescein isothiocyanate) staining to allow visualization of DNA damage with flow cytometry or fluorescence microscopy. Thymine dimer‐specific fluorescence in nuclear DNA of the marine diatom Cyclotella sp. was linearly related to the UVBR dose. Simultaneous measurements of cellular DNA content showed that the vulnerability of G2 cells to DNA damage did not differ significantly from the vulnerability of G1 cells. The formation and removal of thymine dimers in Cyclotella sp. cells was monitored for 3 consecutive days at two realistic UVBR irradiance levels. Thy‐mine dimers were removed within 24 h when exposed to a saturating photosynthetically active radiation intensity following the UVBR treatment. This new method allows the study of UVBR‐induced DNA damage on a cell‐to‐cell basis. It is also feasible for field studies because cells remain intact and can be recognized readily after antibody treatment.
RESPONSES OF FRESHWATER ALGAE TO INHIBITORY VANADIUM CONCENTRATIONS: THE ROLE OF PHOSPHORUS1
Authors: Nalewajko Czeslawa , Lee Kenneth , Olaveson Mary 
Published: October 2004

ABSTRACT We found that species‐specific differences exist among a variety of freshwater algae and cyanobacteria in the extent to which growth and photosynthesis are inhibited by vanadium. A major factor controlling the degree of inhibition by vanadium was the phosphorus state (P‐sufficient vs. P‐deficient) of the organisms. In P‐sufficient cultures, vanadium was inhibitory when the vanadium concentration exceeded the phosphate concentration. In P‐deficient cultures, the depression of photosynthesis by vanadium increased with increasing phosphorus deficiency. Our conclusion that vanadium competed with phosphate for uptake sites was supported by the following three observations: 1) the decreased influx of 32P‐PO
4
into P‐deficient cells in the presence of vanadium, 2) the amelioration of vanadium inhibition of photosynthesis by the addition of phosphate, and 3) the accumulation of vanadium by cells. At vanadium concentrations that severely inhibited growth, the cells of Scenedesmus obliquus (Turp.) Kruger were larger than normal and contained more vacuoles, lipid, and starch bodies than normal cells. Four‐celled coenobia were replaced by unicells. Scenedesmus acutusf: alternans Hortobagyi cells from vanadium‐inhibited cultures had 7.5 times more vanadium per cell than control cultures and contained numerous granules that did not stain for polyphosphate and may be composed of condensed vanadate molecules. The cellular P quota and turnover time of PO4in the medium are important regulators of the extent of inhibition by vanadium.
THE EFFECTS OF TEMPERATURE, IRRADIANCE, AND NITROGEN ON THE ENCYSTMENT AND GROWTH OF THE FRESHWATER DINOFLAGELLATESPERIDINIUM CINCTUMANDP. WILLEIIN CULTURE (DINOPHYCEAE)1
Authors: Chapman Andrew D. , Pfester Lois A. 
Published: October 2004

ABSTRACTEffects of temperature, irradiance, and nitrogen availability on the encystment and growth of the freshwater dinoflagellatesPeridinium cinctumEhrenberg andPeridinium willeiHuitfeld‐Kaas were studied in culture. Lack of nitrogen was the main trigger of encystment in both species. Irradiance had a secondary effect on the percentage of the population of each species that encysted. Temperature did not significantly affect encystment in either species. In both species, only a small percentage of the population underwent encystment. Low light had an inhibitory effect on the growth ofP. willeigrowing in nitrogen‐sufficient medium.
STEROLS OF 14 SPECIES OF MARINE DIATOMS (BACILLARIOPHYTA)1
Authors: Barrett Stephanie M. , Volkman John K. , Dunstan Graeme A. , LeRoi Jeannie‐Marie 
Published: October 2004

ABSTRACT The sterol compositions of 14 species of marine diatoms were determined by gas chromatography and gas chromatography‐mass spectrometry. A variety of sterol profiles were found. The sterols 24‐methylcholesta‐5,22E‐dien‐3β‐ol, cholest‐5‐en‐3β‐ol, and 24‐methylcholesta‐5,24(28)‐dien‐3β‐ol, previously described as the most common sterols found in diatoms, were major sterols in only a few of the species. In light of this and other recent data, it is clear that these three sterols are not typical constituents of many diatom species. Most of the centric species examined had 24‐methylcholesta‐5,24(28)‐dien‐3β‐ol and 24‐methylcholest‐5‐en‐3β‐ol as two of their major sterols. The exception was Rhizosolenia setigera, which possessed cholesta‐5,24‐dien‐3β‐ol as its single major sterol. In contrast to the centric species, the pennate diatoms examined did not have any particular sterols common to most species. Minor levels ofΔ7‐sterols, rarely found in large amounts in diatoms, were found in four species. C29sterols were found in many species; seven contained 24‐ethylcholest‐5‐en‐3β‐ol and three contained 24‐ethylcholesta‐5,22E‐dien‐3β‐ol, reinforcing previous suggestions that C29 sterols are not restricted to higher plants and macroalgae. 24‐Ethylcholesta‐5,22E‐dien‐3β‐ol may prove to be useful for taxonomy of the genus Amphora and the order Thalassiophysales. A major sterol of Fragilaria pinnata was the uncommon algal sterol 23,24‐dimethylcholesta‐5,22E‐dien‐3β‐ol. Cholesta‐5,24‐dien‐3β‐ol was the only sterol found in the culture of Nitzschia closterium. This differed from previous reports of 24‐methylcholesta‐5,22E‐dien‐3β‐ol as the single major sterol in N. closterium. Two C28 sterols possessing an unusual side chain were found in Thalassi‐onema nitzschioides, a C28:2 sterol (16%) and a C28:1 sterol in lower abundance (2.5%), which may be 23‐methylcholesta‐5,22E‐dien‐3β‐ol and 23‐methyl‐5α‐cholest‐22E‐en‐3β‐ol, respectively. The species Cylindrotheca fusiformis, T. nitzschioides, and Skeletonema sp. may be useful as direct sources of cholesterol in mariculture feeds due to their moderate to high content of this sterol.
THE INTERACTION BETWEEN INORGANIC CARBON ACQUISITION AND LIGHT SUPPLY IN PALMARIA PALMATA (RHODOPHYTA)1
Authors: Kübler Janet E. , Raven John A. 
Published: October 2004

ABSTRACT The dependence of the carbon concentrating mechanism of Palmaria palmata (L.) Kuntze on the growth light level was examined 1) to determine whether or not there is a threshold photon flux density (PFD) at which the inorganic carbon uptake mechanism can operate and 2) to attempt to quantify the relative energetic costs of acclimation to the two different limiting factors, PFD and dissolved inorganic carbon (DIC) concentration. Plants were grown at six PFDs: 5, 25, 50, 75, 95, and 125 μmol photons. m−2.s−1. Growth rates increased with increasing PFD from 5 to 50 μmol photons. m−2. s−1 and were light‐saturated at 75, 95, and 125 μmol photons. m−2. s−1 Values of δ13C increased continuously with increasing growth PFD and did not saturate over the range of light levels tested. Time‐resolved fluorescence characteristics indicated a progressive photoacclimation below 50 μmol photons. m−2. s−1. Analysis of chlorophyll fluorescence induction showed three levels of light use efficirncy associated with growth at 5 or 25, 50, and >75 μmol photons. m−2. s−1. The light‐haruesting efficiency was inversely proportional to the effectiveness of DIC acquisition in plants grown at the six PFDs. These data were interpreted to indicate that there is a physiological tradeoff between photosynthetic efficiency and bicarbonate use in this species.