bluuebunny/crossref_metadata_2025 huggingface dataset:
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

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

Protoplasts 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

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

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

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

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

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

Twenty‐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

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

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

Effects 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

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

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.
GROWTH CHARACTERISTICS OF PHYTOPLANKTON DETERMINED BY CELL CYCLE PROTEINS: PCNA IMMUNOSTAINING OF DUNALIELLA TERTIOLECTA (CHLOROPHYCEAE)1
Authors: Lin Senjie , Chang Jeng , Carpenter Edward J.
Published: October 2004

By immunohistochemistry and immunofluorescence methods, we observed that the analog of proliferating cell nuclear antigen (PCNA) in Dunaliella tertiolecta Butcher (Chlorophyceae) was exclusively located in the nucleus. Among positively stained cells, PCNA abundance varied, being highest in S‐phase cells, lower in others, and undetectable in early G1‐ or late M‐phase cells. In exponentially growing and partially synchronized cultures, the percentage of PCNA‐stained cells (% PCNA‐stained cells) oscillated in the photocycle (12:12 h LD). It increased during the light period and reached a peak (75%) before the onset of the dark period when the culture was mainly (71%) in the S phase of the cell cycle. The DNA synthesis inhibitor, hydroxyurea, depressed PCNA abundance, whereas no effect was detected for the mitosis inhibitor colchicine. We conclude that PCNA in D. tertiolecta is associated with the S phase of the cell cycle where it is accumulated and functioning.

PCNA was used to characterize the growth pattern of cultures grown in different media, temperatures, and growth stages. The time lag between the PCNA‐stained phase and the M phase was very short in a continuous culture grown in reduced f/2 medium at 22°C and was considerably longer in the cultures grown in f/2 at 15°C. When an exponentially growing culture grew older, % PCNA‐stained cells decreased. In a late stationary culture where there was no net growth, a small number of cells were still cycling through the PCNA‐stained phase and cell division. In the continuous culture grown at 22°C, the duration of the PCNA‐stained phase (Ts) was 13 h. Calculations with this Ts and % PCNA‐stained cells yielded a growth rate of 0.77 d−1, which was close to that obtained by cell counts (0.69 d−1). Taken together, the results suggest that PCNA is a useful indicator of growth status and a promising cell cycle marker for estimation of species‐specific growth rate.
EFFECTS OF BROMIDE AND IODIDE ON STALK SECRETION IN THE BIOFOULING DIATOM ACHNANTHES LONGIPES (BACILLARIOPHYCEAE)1
Authors: Johnson Lisa M. , Hoagland Kyle D. , Gretz Michael R.
Published: October 2004

Extracellular polymeric substance (EPS) secretion was examined in the stalked marine diatom Achnanthes longipes Ag. in defined medium. This common biofouling diatom exhibited an absolute requirement for bromide for stalk production and substratum attachment, whereas elevated iodide concentrations in the growth medium inhibited stalk formation and adhesion. Varying EPS morphologtes resulted from altering bromide and iodide levels: pads, stalk‐pads, stalks, and no EPS. Cells showed no differences in growth with bromide or iodide concentrations, indicating that they were not physiologically stressed under conditions that impaired EPS secretion. Cells grown in elevated iodide secreted significantly more soluble extracellular carbohydrate into the medium, suggesting that the EPS was soluble and unable to be polymerized into a morphologically distinct gel. By replacing sulfate with methionine, the diatom lost its ability to form stalks even in the presence of bromide, indicating that free sulphate may be required for proper cross‐linking of stalk polymers. Lotus‐FITC, a fluorescent‐tagged lectin, preferentially labeled the EPS and, thus, was used to visualize and quantify EPS secretion along a bromide gradient in conjunction with an image analysis system. This technique demonstrated a direct correlation between the amount of bromide present in the medium and the specific EPS morphology formed.
PHYLOGENY OF AUREOCOCCUS ANOPHAGEFFERENS AND A MORPHOLOGICALLY SIMILAR BLOOM‐FORMING ALGA FROM TEXAS AS DETERMINED BY 18S RIBOSOMAL RNA SEQUENCE ANALYSIS1
Authors: DeYoe Hudson R. , Chan Amy M. , Suttle Curtis A.
Published: October 2004

The 18S ribosomal RNA genes from isolates of the east coast “brown tide” alga Aureococcus anophagefferens (strain Pt‐1) and the Texas “brown tide” alga (strain TBA‐2) were sequenced and compared to the gene sequences of Pelagomonas calceolata, a member of the Pelagophyceae, and 10 other organisms. The genes of A. anophagefferens and strain TBA‐2 consisted of 1814 and 2236 bases, respectively. The difference in length was largely due to a 423‐base insert occurring in the gene of strain TBA‐2. Excluding the insert, 93% of the bases of the aligned sequences were identical. Phylogenetic analyses were performed based on two different alignment refinement methods (eye refinement and Gatesy refinement). Trees inferred from the Jukes‐Cantor distance matrices using the neighbor‐joining method were similar for both alignment methods. In both trees, A. anophagefferens, strain TBA‐2, and P. calceolata formed a monophyletic group with A. anophagefferens and P. calceolata being sister taxa and strain TBA‐2 occurring on a deeper‐rooted branch. Bootstrap data sets for both alignment methods gave strong support for the Pelagophyceae group and the branches within that group. Parsimony analyses using the two alignments gave one tree for the eye‐refined alignment and two trees for the Gatesy method. All three trees had nearly the same topology as the trees inferred from the distance method. In addition, the Pelagophyceae group and the branches within that group were supported by bootstrap analyses and decay indices. Based on the available data, A. anophagefferens and strain TBA‐2 should be placed in the Pelagophyceae but not in the same order and family as P. calceolata.
PHYLOGENETIC POSITION OF BOTRYOCOCCUS BRAUNII (CHLOROPHYCEAE) BASED ON SMALL SUBUNIT RIBOSOMAL RNA SEQUENCE DATA1
Authors: Sawayama Shigeki , Inoue Seiichi , Yokoyama Shin‐ya
Published: October 2004

A small subunit ribosomal RNA (16S‐like rRNA) in the hydrocarbon‐rich microalga Botryococcus braunii Kützing (Chlorophyceae) was amplified using RNA polymerase chain reaction, and its sequence was determined. The sequence data of B. braunii were analyzed with those of several other algae in order to determine phylogenetic relationships among these algae. Phylogenetic analysis indicated B. braunii to be a member of the Chlorophyta and possibly related to Characium vacuolatum and Dunaliella parva.
OBSERVATIONS ON A CHAMAESIPHONACEOIS ALGA (CYANOPHYCEAE) WITH SPECIAL REFERENCE TO EXOCYTE FORMATION1,2
Authors: Rosowski James R. , Bielik Ivan , Lee Kit W.
Published: October 2004

A unicellular cyanophycean culture contaminant had features of both Geitleribactron Kom. and Cyanophanon Geitl. The cells were elongated, sheathless, mostly similar in diameter throughout their length, and attached polarly in rosettes or groups and produced only a single elongated exocyte (=exospore). Young cells were moderately elongated and resembled Geitleribactron. As cells aged, they greatly elongated and then resembled Cyanophanon. Some cells formed Y‐shaped bifurcations, features of C. mirabile Geitl. and C. minus Geitl., but they lacked the basal sheath (pseudovagina) of C. mirabile. During exocyte formation, a thick and localized L‐II wall layer protuberance extended the exocyte away from the parent cell. This terminal wall thickening then appeared to move to one side from subsequent and unequal cell wall growth. Cells sovnetimes bent abruptly, occasionally opposite a thickening in the L‐II wall layer. Further studies in culture of putative Geitleribactron and Cyanophanon isolates are necessary to ascertain the breadth of their structural diversity and the identity of the present taxon.
GOMPHONEIS MESTA (BACILLARIOPHYTA). II. MORPHOLOGY OF THE INITIAL FRUSTULES AND PERIZONIUM ULTRASTRUCTURE WITH SOME INFERENCES ABOUT DIATOM EVOLUTION1
Authors: Passy‐Tolar Sophia I. , Lowe Rex L.
Published: October 2004

The morphology of initial frustules of Gomphoneis mesta Passy‐Tolar & Lowe was studied with light and scanning electron microscopy The structure of the raphe, central nodule, stigma, striae, and apical pore field in post‐auxospore generations was described. Discovery of internal chambers and an axial plate in very early stages of the life cycle of G. mesta reveals a possible evolutionary connection with the Herculeana group (sensu Kociolek and Stoermer 1989) and suggests that the loss of axial plates is a secondary event. Polarization of the characters “stigma number” and “outline of the internal stigmal opening” is proposed. A perizonium, composed of transverse and longitudinal bands, is reported for the first time in the genus Gomphoneis.
CYTOMORPHOLOGICAL CHARACTERIZATION OF THE PLANKTONIC DIAZOTROPHIC CYANOBACTERIA TRICHODESMIUM SPP. FROM THE INDIAN OCEAN AND CARIBBEAN AND SARGASSO SEAS1
Authors: Janson Sven , Siddiqui Pirzada J. A. , Walsby Anthony E. , Romans Kristen M. , Carpenter Edward J. , Bergman Birgitta
Published: October 2004

Trichodesmium Ehrenberg species were collected in the Caribbean Sea, Sargasso Sea, and coastal areas of Tanzania (Indian Ocean). The specimens were divided into five species on the basis of morphometric characters such as cell dimensions and colony formation: T. tenue Wille, T. erythraeum Ehrenberg, T. thiebautii Gomont, T. hildebrandtii Gomont, and T. contortum Wille. In addition, Trichodesmium sp., a spherical colony of uncertain taxonomic position was examined. The cell structure of each species was investigated by means of light, scanning electron, and transvnission electron microscopy. Particular attention was paid to the presence and ultrastructural arrangement of gas vacuoles and glycogen fiber clusters (GFCs). This resulted in identification of two major groups of species: 1) T. tenue, Trichodesmium sp. with spherical‐shaped colonies, and T. erythraeum with GFCs and more or less localized gas vacuoles; and 2) T. thiebautii, T. hildebrandtii, and T. contortum lacking GFCs and with gas vacuoles spread at random. The species within each group were further characterized with respect to the dimension of the gas vesicles, cylindrical bodies, scroll bodies, and a new cellular inclusion body, Differences in colony formation and cell dimensions correlated with specific ultrastructural characters in five of the six forms. This is the first ultrastructural study comparing different forms of Trichodesmium sampled at geographically remote areas and shows that one species appears identical regardless of the sampling site. Some of the species had not been investigated earlier, and probably more species are to be identified and analyzed.
EFFECTS OF SHADING BY ADULTS ON THE GROWTH OF BLADE‐STAGE MACROCYSTIS PYRZFERA (PHAEOPHYTA) DURING AND AFTER THE 1982–1984 EL NIÑO1
Authors: Schroeter Stephen C. , Dean Thomas A. , Thies Karl , Dixon John D.
Published: October 2004

The effect of shading by an adult canopy on blade‐stage Macrocystis pyrifera (L.) C. A. Agardh was estimated by comparing the average growth rate of individuals under a canopy to that of individuals in a canopy gap. This comparison was made in 1983 during a strong El Niño and again in 1986 after the El Niño. Estimated nutrient concentrations in 1983 were two orders of magnitude below those in 1986, whereas ambient light levels were over 3 times higher. The kelp canopy caused similar proportional light reductions (20–30%) during both years. Blades grew 18% slower under the canopy than in the clearing in 1983 and about 77% slower under the canopy in 1986. Blade‐stage individuals grew at the same rates in clearings in 1983 and 1986. Regardless of shading, the average growth rate of blade‐stage kelp under the ambient, low‐nutrient conditions of 1983 was higher than that later observed for multifronded juveniles during the same El Niño. The growth of blade‐stage kelp was more like that of larger juveniles growing under high‐nutrient conditions. The difference may be due to greater concentrations of nutrients very near the sea floor where single blades are growing compared to concentrations higher in the water column where larger kelp have most of their tissues.
PHOTOSYNTHETIC CHARACTERISTICS OF THE COCCOLITHOPHORID EMILIANIA HUXLEYI (PRYMNESIOPHYCEAE) EXPOSED TO ELEVATED CONCENTRATIONS OF DISSOLVED INORGANIC CARBON1
Authors: Nielsen Marianne V.
Published: October 2004

Light‐saturated photosynthesis (Pmax) of Emiliania huxleyi (Lohmann) Hay et Mohler is known to be carbonlimited at natural concentrations of dissolved inorganic carbon (DIC). In the present study, light‐limited and light‐saturated photosynthetic rates of E. huxleyi were studied at three concentrations of DIC (2.4, 7.4, and 12.4 mM) for high‐calcite (Cin/Ctot=0.48) and low‐calcite (Cin/Ctot=0.08) cells of the same strain. The photosynthetic efficiency (α) and the maximum quantum yield (θmax)A increased by more than a factor of 2 from the lowest to the highest DIC level. Pmax a, and θmax were always higher for the high‐calcite than for the low‐calcite cells at identical DIC levels. This may indicate that the calcifcation process acts as an extra supplier of CO2 for photosynthesis making the CO2 shortage at natural DIC levels a little smaller for high‐calcite than for low‐calcite E. huxleyi. A dependency of θmax on DIC has not previously been shown for marine phytoplankton. θmax is a key parameter in recent biooptical models of phytoplankton productivity, and the results from the present study are therefore important for modeling the productivity of E. huxleyi.
TEMPERATURE AND IRRADIANCE EFFECTS ON GROWTH OF PITHOPHORA OEDOGONIA (CHLOROPHYCEAE) AND SPIROGYRA SP. (CHAROPHYCEAE)1
Authors: O'Neal Steven W. , Lembi Carole A.
Published: October 2004

Growth responses of Pithophora oedogonia (Mont.) Wittr. and Spirogyra sp. to nine combinations of temperature (15°, 25°, and 35°C) and photon flux rate (50, 100, and 500 μmol·m−2·s−1) were determined using a three‐factorial design. Maximum growth rates were measured at 35°C and 500 pmol·m−2·s−1 for P. oedogonia (0.247 d−1) and 25°C and 500 μmol·m−2·s−1 for Spirogyra sp. (0.224 d−1). Growth rates of P. oedogonia were strongly inhibited at 15°C (average decrease= 89%of maximum rate), indicating that this species is warm stenothermal. Growth rates of Spirogyra sp. were only moderately inhibited at 15° and 35°C (average decrease = 36 and 30%, respectively), suggesting that this species is eurythermal over the temperature range employed. Photon flux rate had a greater influence on growth of Spirogyra sp. (31% reduction at 50 pmol·m−2·s−1 and 25°C) than it did on growth of P. oedogonia (16% reduction at 50 μmol·m−2·s−1 and 35°C). Spirogyra sp. also exhibited much greater adjustments to its content of chlorophyll a (0.22–3.34 μg·mg fwt−1) than did P. oedogonia (1.35–3.08 μg·mg fwt−1). The chlorophyll a content of Spirogyra sp. increased in response to both reductions in photon flux rate and high temperatures (35°C). Observed species differences are discussed with respect to in situ patterns of seasonal abundance in Surrey Lake, Indiana, the effect of algal mat anatomy on the internal light environment, and the process of acclimation to changes in temperature and irradiance conditions.
SEASONAL VARIATIONS IN PHOTOSYNTHESIS‐IRRADIANCE RESPONSES BY BIOFILMS IN MEDITERRANEAN STREAMS
Authors: Guasch Helena , Subater Sergi
Published: October 2004

The relationships between primary production and irradiance were analyzed over an annual cycle in natural biofilms of two undisturbed streams: La Solana (LS), an open calcareous stream, and Riera Major (RM), a shaded siliceous stream. In LS, low photosynthetic efficiency (αchl and αarea) and high values of both the light saturation parameter (Ik) and the carotenoid/chlorophyll ratio indicated adaptation to high light regimes. On the other hand, higher photosynthetic efficiency and lower Ik as well as photoinhibition at high irradiance found in the biofilms of RM indicated shade adaptation. However, the lack of correlation between light availability in nature and the photosynthetic parameters studied in the laboratory suggested that light was not the most important factor in determining seasonal changes in the photosynthetic behavior in this stream. Both in the open and shaded streams, algal patches collected simultaneously exhibited different photosynthesis‐irradiance (P‐I) curues, showing that community composition influenced the P‐I parameters. In the open stream (LS), however, significant negative correlations between αarea and chlorophyll a and between Pmaxchland chlorophyll a (r=‐0.994, P < 0.001, and r =‐0.929, P < 0.05, respectively) suggested that photosynthesis was affected by self‐shading. Due to the absence of photoinhibition in the biofilms of LS, high photosynthetic rates were maintained at the ambient high light environment, thus compensating for low photosynthesis at low irradiance. In the shaded stream (RM), because photosynthesis was saturated at low irradiances, primary production was relatively high given the low light conditions.
LIGHT RESPIRATION IN SIX ESTUARINE PHYTOPLANKTON SPECIES: CONTRASTS UNDER PHOTOAUTOTROPHIC AND MIXOTROPHIC GROWTH CONDITIONS1
Authors: Lewitus Alan J. , Kana Todd M.
Published: October 2004

The photoresponse of respiration was examined in six estuarine phytoplankton species grown at a limiting irradiance in the presence or absence of glucose. Cellular respiration rates in the dark, at the growth irradiance, and at saturating light levels were higher in glucose‐grown cultures than in photoautotrophic cultures. Glucose uptake also affected the relationship between incident irradiance and gross respiration rate, and the specific respiratory pathways that contributed to the respiration versus irradiance (R vs. I) response. The energy‐conseming Mehler reaction contributed largely to light‐stimulated respiration in photoautotrophic (energy‐limited) cultures. However, the energy‐dissipating alternative pathway was the predominant form of respiration measured in mixotrophic (energy‐sufficient) cultures. Based on these and previous observations, a model of phytoplankton R us. I response is presented, in which the relative contributions of different light respiratory processes (cytochrome pathway respiration, alternative pathway respiration, chlororespiration, Mehler reaction) are dependent on the incident irradiance and cellular energy content.
GROWTH CHARACTERISTICS OF MARINE PHYTOPLANKTON DETERMINED BY CELL CYCLE PROTEINS: THE CELL CYCLE OF ETHMODISCUS REX (BACILLARIOPHYCEAE) IN THE SOUTHWESTERN NORTH ATLANTIC OCEAN AND CARIBBEAN SEA1
Authors: Lin Senjie , Carpenter Edward J.
Published: October 2004

Ethmodiscus spp. is an important contributor to oceanic tropical‐ooze sediments and thus might be an important transport vehicle of carbon from the ocean surface to sediments. The knowledge of its cell cycle and growth rate, which is still lacking, is necessary to evaluate the importance of Ethmodiscus in nutrient cycling and to solve the discrepancy between its high sedimentary abundance and rarity in the plankton. We used immunofluorescence of a cell cycle protein, prolqerating cell nuclear antigen (PCNA), and DNA‐specific staining to study the progression of the cell cycle and roughly estimate the growth rate for E. rex (Rattray) Wiseman and Hendey in the southwestern North Atlantic Ocean and Caribbean Sea in June 1994 and January 1995.

During the cell division cycle, the chloroplasts appeared to synthesize DNA before the nucleus (S phase). Following the S phase, the nucleus moved from one end of the cell toward the center underneath the midline of the girdle band (G2 phase) where it divided (M phase). During a very brief period, the parent cell split and moved apart from the girdle midline, and two new valves were produced (late M phase). The two daughter nuclei apparently remained attached at the joint of the two newly produced valves, where they appeared to be responsible for coordinating the symmetrical formation of the new valves. The morphologically complete daughter cells remained joined for a short period of time before separating into solitary cells whose nucleus was located at one end of the cell. Derived from the phase fraction curves, the duration of the cell cycle phases decreased in the order from G1, S, G2, to M. A conservative estimate of the growth rate in the study area obtained by using PCNA immunostaining was 0.39–0.46 d−1 in June and 0.15 d−1 in January. The validity and implication of the growth rate estimates are discussed.
SPECIES‐SPECIFIC DIFFERENCES OF PYRENOIDS IN CHLORELLA (CHLOROPHYTA)1
Authors: Ikeda Taiji , Takeda Hiroshi
Published: October 2004

The structure of the pyrenoid supports the separation of Chlorella species into two groups based on cell wall chemistry and suggests evolutionary relationships. Chlorella species with a glucan‐type wall exhibit quite diverse pyrenoid structures, which may indicate that these species are not closely related. Those species with glucosamine cell walls (C. kessleri, C. sorokiniana, C. vulgaris) are virtually identical in pyrenoid morphology, indicating a closer evolutionary relationship. In the species with glucosamine walls, the thylakoid that penetrates into the pyrenoid matrix, is unijormly double‐layered. Pyrenoids in the species with glucan walls show various features: 1) a pyrenoid matrix only, 2) a pyrenoid traversed by a few discs of double thylakoids with many adhering pyrenoglobuli, 3) a pyrenoid penetrated with tubelike structures or 4) a pyrenoid penetrated with many single undulating thylakoids. The pyrenoid structure of the symbiotic Chlorella in Paramecium bursaria resembles those of free‐living Chlorella with glucosamine walls.
GENETIC VARIABILITY AND PARENTAGE IN MACROCYSTIS PYRZFERA (PHAEOPHYCEAE) USING MULTI‐LOCUS DNA FINGERPRINTING1
Authors: Coyer James A. , Robertson Deborah L. , Alberte Randall S.
Published: October 2004

Multi‐locus DNA fingerprints using an M13 probe were obtained for two individuals of Macrocystis pyrifera (L.) C. Ag. collected from Monterey Bay, California, and their laboratory‐reared offspring. DNA was extracted from each of two field‐collected individuals (= parents), their self‐fertilized diploid offspring (three and seven individuals), and one diploid individual resulting from spores of the two parents. A total of 20 bands (4–19 kb) was detected among all individuals, ranging from 7 to 14 bands for any one individual. Two bands were present in all individuals, and three bands were unique to one parent and its three progeny. Ten bands were observed in the out‐crossed individual, of which three were inherited from one parent, two from the other parent, and five were present in both parents. Genetic similarity between each parent and their self‐fertilized offspring was significantly higher than similarity between the two self‐fertilized groups. The data show that multi‐locus DNA fingerprints can be used to assess parentage in the giant kelp and that there is consistent agreement between genetic similarity and known genetic relatedness among parents and offspring.
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

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

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

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.