bluuebunny/crossref_metadata_2025 huggingface dataset:
DETECTION OF CHLOROPHYLL C1 AND MAGNESIUM‐2,4‐DIVINYLPHEOPORPHYRIN A5 MONOMETHYLESTER IN CRYPTOPHYTES1
Authors: Schimek Christine , Stadnichuk Igor N. , Knaust Rosemarie , Wehrmeyer Werner
Published: October 2004

Three different chlorophyll (chl) c‐type pigments were isolated from two cryptophyte species by silica thin‐layer chromatography or polyethylene high‐performance liquid chromatography. Chroomonas sp. Hansgirg contained chl c1 and magnesium‐2,4‐divinylpheoporphyrin a, mono‐methylester; chl c2 and magnesium‐2,4‐divinylpheoporphyrin a5 monomethylester were found in Cryptomonas maculata (syn. Rhodomonas maculata Butcher). These identifications were based on spectral characteristics and on comparison with reference pigments isolated from the synurophycean Synura petersenii Korshikov and the prasinophyte Mantoniella squamata Manton & Park. Neither of the cryptophyte species contained chl c1 and chl c2. The significance of chl c1 as a major pigment and the occurrence of magnesium‐2,4‐divinylpheoporphyrin a5 monomethylester in cryptophytes are discussed.
PHOTOINHIBITION OF MECHANICALLY STIMULABLE BIOLUMINESCENCE IN THE AUTOTROPHIC DINOFLAGELLATE CERATIUM FUSUS (PYRROPHYTA)1
Authors: Sullivan James M. , Swift Elijah
Published: October 2004

Ceratium fusus (Ehrenb.) Dujardin was exposed to light of different wavelengths and photon flux densities (PFDs) to examine their effects on mechanically stimulable bioluminescence (MSL). Photoinhibition of MSL was proportional to the logarithm of PFD. Exposure to I μmol photons·m−2s−1 of broadband blue light (ca. 400–500 nm) produced near‐complete photoinhibition (≥90% reduction in MSL) with a threshold at ca. 0.01 μmol photons·m−2·s−1. The threshold of photoinhibition was ca. an order of magnitude greater for both broadband green (ca. 500–580 nm) and red light (ca. 660–700 nm). Exposure to narrow spectral bands (ca. 10 nm half bandwidth) from 400 and 700 nm at a PFD of 0.1 μmol photons·m−2·s−1 produced a maximal response of photoinhibition in the blue wavelengths (peak ca. 490 nm). A photoinhibition response (≥ 10%) in the green (ca. 500–540 nm) and red wavelengths (ca. 680 nm) occurred only at higher PFDs (1 and 10 μmol photons·m−2·s−1). The spectral response is similar to that reported for Gonyaulax polyedra Stein and Pyrocystis lunula Schütt and unlike that of Alexandrium tamarense (Lebour) Balech et Tangen. The dinoflagellate's own bioluminescence is two orders of magnitude too low to result in self‐photoinhibition. The quantitative relationships developed in the laboratory predict photoinhibition of bioluminescence in populations of C. fusus in the North Atlantic Ocean.
STRUCTURE OF THE CAPSULAR AND EXTRACELLULAR POLYSACCHARIDES PRODUCED BY THE DESMID SPONDYLOSIUM PANDURIFORME (CHLOROPHYTA)1
Authors: Paulsen Berit Smestad , Vieira Armando Augusto Henriques
Published: October 2004

The filamentous desmid Spondylosium panduriforme (Heimerl) Teiling var. panduriforme f. limneticum (West & West) Teiling (Desmidiaceae), strain 072CH‐UFCAR, is surrounded by a well‐defined, mucilaginous capsule consisting of a capsular polysaccharide (CPS). This microalga also produces an extracellular polysaccharide (EPS), which can be isolated from the culture medium. Analysis of the carbohydrate composition of the two polymers by gas chromatography showed that they were different. Both were composed, of galactose, fucose, xylose, arabinose, rhamnose, and glucose but in different amounts. For example, glucuronic acid accounts for 24% of the EPS material but only traces were found in the CPS. Significant differences were also found during methylation analysis. Fucose appeared to have a higher degree of branching in the EPS than in the CPS. These branches were located on C‐3 and could be the position for the attachment of the glucuronic acid units in the EPS. The glucuronic acid was present as 1→4‐linked and terminal units. A possible explanation for the formation of the EPS is suggested.
COMPARATIVE ANALYSIS OF THE FINE STRUCTURE OF YOUNG AND ADULT INDIVIDUALS OF DUNALIELLA SALINA (POLYBLEPHARIDACEAE, CHLOROPHYCEAE) WITH EMPHASIS ON THE FLAGELLAR APPARATUS1
Authors: Leonardi Patricia I. , Cáceres Eduardo J.
Published: October 2004

Individuals of Dunaliella salina (Dunal.) Teod. change their shape during ontogenesis. Here we describe the fine structure of this species with emphasis on distinctions between young and adult individuals. The cell coat is present at early stages of cell development and may be synthesized by vesicles of nuclear membrane‐associated endoplasmic reticulum. Scanning electron microscopical observations show differences in the surface pattern of the cell coat in young and adult cells. The nucleus of young cells is more or less spherical, whereas that of adult cells is pyriform. The Golgi apparatus is positioned immediately under the basal bodies and consists of three dictyosomes in young cells and six to eight dictyosomes in adult cells. The flagellar apparatuses of young and adult cells have a 1/7 o'clock (i.e. clockwise) displacement of basal bodies and are grossly similar, but there are subtle differences between specific components. Two non‐axonemic basal bodies (1′, 2′) appear in a plane perpendicular to that determined by the flagella‐bearing basal bodies (1, 2). The cruciate microtubular rootlet system has a 4–2–4–2 alternation pattern. In adult cells, rhizoplasts emerge from each terminal body and run parallel to the four rootlets.
ISOLATION AND CHARACTERIZATION OF A DNA VIRUS INFECTING FELDMANNIA SIMPLEX (PHAEOPHYCEAE)1
Authors: Friess‐Klebl Anne‐K. , Knippers Rolf , Müller Dieter G.
Published: October 2004

We report on the isolation and characterization of a virus that is formed in modified zoidangia of the marine brown alga Feldmannia simplex (Crouan) Hamel (Ectocarpales, Phaeophyceae). Isolated virus particles had a buoyant density of about 1.35 g·mL−1 in CsCl equilibrium gradients. They contained one major polypeptide (MW = 55,000) and at least six additional polypeptides (MW = 15,000–120,000). Four of these proteins were glycosylated. The viral genome consisted of double‐stranded DNA and formed two freely migrating fractions in pulsed‐field‐gel electrophoresis, namely linear DNA with a size of 220 kilobase pairs, and fragments of 10–60 kilobase pairs. However, electron microscopic examination revealed that a substantial fraction of the viral DNA occurred as closed circles. We suggest that the viral DNA in native particles is circular but tends to break at random sites during the preparation.
FLAGELLAR HAIRS IN PRASINOPHYTES (CHLOROPHYTA): ULTRASTRUCTURE AND DISTRIBUTION ON THE FLAGELLAR SURFACE1
Authors: Marin Birger , Melkonian Michael
Published: October 2004

The flagellar hair ultrastructure of 16 strains of species of the prasinophycean genera Mantoniella, Mamiella, Pseudoscourfieldia, Nephroselmis, Tetraselmis, Scherffelia, Pterosperma, and Pyraminonas was examined in detail by whole‐mount electron microscopy. The flagellar hairs of all genera displayed a high degree of ultrastructural complexity that was completely conserved within each strain. In all strains, flagellar hairs occurred on the sides of the flagella (lateral hairs); in several strains, special flagellar hairs also were found on the flagellar tips (tip hairs; absent in the Chlorodendrales and in Nephroselmis). Two groups of lateral hairs were distinguished: 1) T‐hairs (“Tetraselmis‐type” flagellar hairs), characterized by a smooth, tubular shaft of ca. 15 nm diameter and an overall length of 0.5–1.3 μm, and 2) Pt‐hairs (“Pterosperma‐type lateral flagellar hairs”), which were considerably longer (ca. 1.5–5.4 μm), characterized by a thick shaft of ca. 30 nm diameter, which was covered with a layer of regularly spaced small particles of ca. 10 nm diameter. In both groups of flagellar hairs, a strain‐specific number of subunits (1–101) in linear arrangement was attached to the distal end of the shaft. Tip hairs were either structurally related to T‐hairs (Mamiellales, Pseudoscourfieldia) or represented a separate group, Pt‐hairs (“Pterosperma‐type flagellar tip hairs”; Pterosperma, Pyramimonas). In four genera (Mantoniella, Mamiella, Pseudoscourfieldia, Nephroselmis), both groups of lateral hairs occurred together on the same cell. Interestingly in these taxa the Pt‐hairs were exclusively attached to the shorter immature flagella (no. 2), but, in contrast, in Mantoniella and Pseudoscourfieldia the tip hairs were restricted to the longer mature flagellum (no. 1). Thus, flagella of different developmental status differ in their hair‐scale complement. The occurrence, distribution, and ultrastructure of flagellar hairs can be used to identify and classify prasinophytes at all taxonomic levels.
FLAGELLAR APPARATUS STRUCTURE IS SIMILAR BUT NOT IDENTICAL IN VOLVULINA STEINII, EUDORINA ELEGANS, AND PLEODORINA ILLINOISENSIS (CHLOROPHYTA): IMPLICATIONS FOR THE “VOLVOCINE EVOLUTIONARY LINEAGE”1
Authors: Hoops Harold J. , Long Jennifer J. , Hile Elizabeth S.
Published: October 2004

The colonial and multicellular members of the Volvocales can be arranged in order of increasing size and complexity as the “volvocine series.” This series is often assumed to reflect an evolutionary progression. The flagellar apparatuses of previously examined algae are not consistent with a simple lineage. The flagellar apparatuses of Astrephomene gubernaculifera Pocock, Gonium pectorale Müller, Platydorina caudata Kofoid, Volvox rousseletii G. S. West, and V. carteri f. weismannia (Powers) Iyengar differ from one another, and there is no apparent progression inflagellar apparatus features from the simple to complex colonial forms. We examined the flagellar apparatuses of Volvulina steinii Playfair, Eudorina elegans Ehr., and Pleodorina illinoisensis Kofoid and found them to be similar to one another. The basal bodies are connected by a distal fiber that is offset to the anti side of the cell. Two microtubular rootlets originate on the inside of the basal bodies and extend toward the syn side. The other two rootlets are oriented perpendicular to the first two and are anti‐parallel to each other. A coarsely striated component underlies the four‐membered rootlets and extends to the basal bodies. A proximal fiber complex connects the two basal bodies. This complex consists of a branched striated component on the cis side of each basal body. One part extends toward the anti side of the cell, while the other extends into a fibrous component that runs between basal bodies. An additional structure extends in the anti direction from the trans side of each basal body. A fibrous component extends past one basal body in all four species. This component goes past the trans basal body in Volvulina steinii and the cis basal body in E. elegans and P. illinoisensis. The flagellar apparatuses of these organisms are similar to those of G. pectorale and Volvox carteri but different from the other colonial volvocalean algae examined. The algae examined in this study plus G. pectorale and V. carteri probably share a common evolutionary history that postdates the transition from the unicellular to colonial habit. Such a shared evolutionary history is a requirement of the volvocine hypothesis. However, we have not observed progressive changes in the flagellar apparatus correlated with increasing cell number, differentiation, and sexual specialization. Thus, it is possible, but not certain, that G. pectorale, Volvulina steinii, E. elegans, P. illinoisensis, and Volvox carteri may form part of a volvocine lineage.
LOCALIZATION OF CA2+‐STIMULATED ATPASE IN THE COCCOLITH‐PRODUCING COMPARTMENT OF CELLS OF PLEUROCHRYSIS SP. (PRYMNESIOPHYCEAE)1
Authors: Kwon Duck‐Kee , González Elma L.
Published: October 2004

Cell homogenates of Pleurochrysis sp. (CCMP299) were fractionated by means of sucrose gradients. Ca2+‐stimulated ATPase (EC 3.6.1.3., ATP phosphohydrolase) was associated primarily with the plasma membrane, Golgi, and high density (1.21 g·cm−3) membranous structures. Ca2+‐stimulated ATPase was highly enriched in the latter. Based on treatments with Triton X‐100 and NBD ceramide, we conclude that the high‐density structures were membrane‐delimited organelles. These vesicle‐like organelles contained complex polysaccharides, a high concentration of calcium, and, upon microscopic examination, structures resembling coccoliths. These findings are consistent with observations on the known composition of coccoliths and the presumed mineralizing function of the sub‐cellular coccolith‐producing compartment. The high‐density vesicles were linked to the Golgi by means of colchicine‐sensitive materials, presumably microtubules. These data and prior ultrastructural observations by other investigators indicating vectorial assembly and secretion suggest that the subcellular movement of the newly formed coccoliths may be directed and/or powered by colchicine‐sensitive cytoskeletal elements. We interpret the data to mean that the high‐density vesicles represent the coccolith‐producing compartment previously observed by others in electron micrographs.
THREE NEW BENTHIC SPECIES OF PROROCENTRUM (DINOPHYCEAE) FROM CARRIE BOW CAY, BELIZE: P. SABULOSUM SP. NOV., P. SCULPTILE SP. NOV., AND P. ARENARIUM SP. NOV.1
Authors: Faust Maria A.
Published: October 2004

Three new benthic, sand‐dwelling dinqflagellate species, Prorocentrum sabulosum, Prorocentrum scuptile, and Prorocentrum arenarium, from coral rubble are described from scanning electron micrographs. Species were identified based on shape, size, surface micromorphology, ornamentation of thecal plates, and architecture of the periflagellar area and intercalary band.

Cells of P. sabulosum are oval with a cell size of 48–50 μm long and 41–48 μm wide. The areolae are round to oval and numerous (332–450 per valve) and range from 1 to 1.6 μm in size. The periflagellar area of P. sabulosum bears a wide V‐shaped depression with a flat ridge and lacks ornamentation; it accommodates six pores: one large flagellar pore, an adjacent smaller auxiliary pore, and four pores of unknown function. The flagellar and auxiliary pores are surrounded by a narrow apical collar. The intercalary band of P. sabulosum is smooth.

Prorocentrum sculptile cells are broadly oval, 32–37 nm long, and 30–32 μm wide in valve view with a deep‐sculptured apical area. The valves are smooth and are marked with shallow depressions (856–975 per valve). Some of these depressions have a small round opening (0.13 μm in diameter). The periflagellar area is V‐shaped with a deeply indented depression; it accommodates the two flagella and a thin angled apical plate. The intercalary band is smooth.

Prorocentrum arenarium cells are nearly round in valve view 30–32 μm in diameter. Thecal surface is smooth with scattered kidney‐shaped valve poroids (65–73 per valve) and marginal poroids (50–57 per valve). Length and width of poroids are 0.62 μm and 0.36 μm, respectively. The periflagellar area is an unornamented, broad triangle into which a large flagellar pore and a smaller auxiliary pore are fitted. Both flagella, longitudinal and transverse, protrude from the flagellar pore. The intercalary band is smooth. The presence of a peduncle‐like structure (2–3 μm long) in P. arenarium was observed situated in the flagellar pore.
NOTE. ISOLATION OF FOUR NEW STRAINS OF CHLAMYDOMONAS REINHARDTII (CHLOROPHYTA) FROM SOIL SAMPLES1
Authors: Sack Lawren , Zeyl Clifford , Bell Graham , Sharbel Timothy , Reboud Xavier , Bernhardt Torsten , Koelewyn Hans
Published: October 2004

We describe a method for the efficient extraction of flagellate phototrophs from soil samples. Soils of various types from a wide range of natural environments were sampled for Chlamydomonas reinhardtii Dangeard. Test matings of candidate unicellular green algae were used to identify 19 heterothallic isolates that were interfertile with lab strains. Four of these isolates were genetically distinct from previously isolated strains and from each other, as indicated by the distribution of two transposons on restriction fragments of their genomic DNA and by allozyme variation at six of nine loci.
TEMPERATURE RESPONSES AND EVOLUTION OF THERMAL TRAITS INCLADOPHOROPSIS MEMBRANACEA(SIPHONOCLADALES, CHLOROPHYTA)1
Authors: Pakker Hans , van Reine Willem F. Prud'homme , Breeman Anneke M.
Published: October 2004

Temperature tolerances and relative growth rates were determined for different isolates of the tropical to warm temperate seaweed speciesCladophoropsis membranacea(C. Agardh) Boergesen (Siphonodadales, Chlorophyta) and some related taxa. Most isolates ofC membranaceasurvived undamaged at 18° C for at least 8 weeks. Lower temperatures (5°–15°C) were tolerated for shorter periods of time but caused damage to cells. All isolates survived temperatures up to 34° C, whereas isolates from the eastern Mediterranean and Red Sea survived higher temperatures up to 36°C. Growth occurred between 18° and 32° C, but an isolate from the Red Sea had an extended growth range, reaching its maximum at 35°C.Struvea anastomosans(Harvey) Piccone & Grunow,Cladophoropsis sundanensisReinbold, and an isolate ofC. membranaceafrom Hawaii were slightly less cold‐ tolerant, with damage occurring at 18°C. Upper survival temperatures were between 32° and 36° C in these taxa. Temperature response data were mapped onto a phylogenetic tree. Tolerance for low temperatures appears to be a derived character state that supports the hypothesis thatC. membranaceaoriginated from a strictly tropical ancestor. Isolates from the Canary Islands, which is near the northern limit of distribution, are ill adapted to local temperature regimes. Isolates from the eastern Mediterranean and Red Sea show some adaptation to local temperature stress. They are isolated from those in the eastern Atlantic by a thermal barrier at the entrance of the Mediterranean.
INHIBITION OF GROWTH OF ULVA EXPANSA (CHLOROPHYTA) BY ULTRAVIOLET‐B RADIATION1
Authors: Grobe Carl W. , Murphy Terence M.
Published: October 2004

We examined the effect of ultraviolet‐B radiation (UV‐B, 290–320 nm) on the growth rate of the intertidal marine alga Ulva expansa (Setch.) S. & G. (Chlorophyta). Segments of thallus collected from a natural population were grown in outdoor seawater tanks. Combinations of UV‐B‐opaque screens, UV‐B‐transparent screens, and UV‐B lamps were used to investigate the effects of solar UV‐B and solar plus supplemental UV‐B on the growth of these segments. Growth was measured by changes in segment surface area, damp weight, and dry weight. Growth rates of segments were inhibited under both solar UV‐B and solar plus supplemental UV‐B treatments. Growth rates were also inhibited by high levels of photosynthetically active radiation, independent of UV‐B fluence. These results indicate that increases in UV‐B resulting from further ozone depletion will have a negative impact on the growth of this alga.
SPATIAL SEGREGATION OF CO2 FIXATION IN TRICHODESMIUM SPP.: LINKAGE TO N2 FIXATION POTENTIAL1
Authors: Paerl Hans W.
Published: October 2004

The aggregate‐forming, nonheterocystous, filamentous blue‐green alga (cyanobacteria) Trichodesmium spp. is a widespread and important planktonic N2 fixer and primary producer in tropical and subtropical oceans. It is unique among nonheterocystous genera because it conducts N2 and CO2 fixation (O2 evolution) simultaneously; a notable achievement, because O2 is a potent inhibitor of N2 fixation. Spatial and temporal CO2 fixation patterns were examined in trichomes and aggregates from natural and cultured populations, utilizing microautoradiographic detection of 14CO2 incorporation. Parallel N2 fixation (acetylene reduction) measurements were also made. Diel N2 and CO2 fixation patterns were similar, with co‐optimization of both processes near midday. Microautoradiographs revealed several trichome‐level 14CO2 incorporation patterns: 1)uniform, heavy labeling, 2)uniform, light labeling, 3) heavier labeling in distal as opposed, to proximal regions, and 4) virtually no labeling throughout. Similar patterns were observed in natural and cultured populations. Given previous immunochemical findings that N2 fixation potential is widespread in Trichodesmium spp. trichomes and aggregates, current results suggest a high degree of individuality, and possibly a “division of labor” in terms of CO2 fixation, among trichomes comprising active N2‐fixing aggregates. Segregation of photosynthesis within and among trichomes facilitates simultaneous N2 and CO2 fixation in Trichodesmium spp. trichomes and aggregates.
THE INABILITY OF THE TEXAS “BROWN TIDE” ALGA TO USE NITRATE AND THE ROLE OF NITROGEN IN THE INITIATION OF A PERSISTENT BLOOM OF THIS ORGANISM1
Authors: DeYoe Hudson R. , Suttle Curtis A.
Published: October 2004

A planktonic alga similar in general morphology and pigments to Aureococcus anophagefferens Hargraves and Sieburth has caused persistent and ecologically damaging blooms along the south Texas coast. Experiments using 100 μM NO3−, NO2−, and NH4+ demonstrated that the alga could not use NO3− for growth but could use NO2− and NH4+. Doubling iron or trace metal concentrations did not permit growth on NO3−. Chemical composition data for cultures grown in excess NO3− or NH4+, respectively, were as follows: N·cell−1 (0.88 vs. 1.3 pg), C:N ratio (25:1 vs. 6.4:1), C:chlorophyll a (chl a) (560:1 vs. 44:1), and chl a·cell−1 (0.033 vs. 0.16 pg). These data imply that cells supplied with NO3− were N‐starved. Culture addition of 10 mM final concentration chlorate (a nitrate analog) did not affect the Texas isolate while NO3− utilizing A. anophagefferens was lysed, suggesting that the NO3− reductase of the Texas isolate is nonfunctional. Rates of primary productivity determined during a dense bloom indicated that light‐saturated growth rates were ca. 0.45 d−1, which is similar to maximum rates determined in laboratory experiments (0.58 d−1± 0.16). However, chemical composition data were consistent with the growth rate of these cells being limited by N availability (C:N 28, C:chl a 176, chl a·cell−1 0.019). Calculations based on a mass balance for nitrogen suggest that the bloom was triggered by an input of ca. 69 μM NH4+ that resulted from an extensive die‐off of benthos and fish.
EFFECTS OF TEMPERATURE ON GROWTH, LIGHT ABSORPTION, AND QUANTUM YIELD IN DUNALIELLA TERTIOLECTA (CHLOROPHYCEAE)1
Authors: Sosik Heidi M. , Mitchell B. Greg
Published: October 2004

The effects of growth temperature on the marine chlorophyte Dunaliella tertiolecta Butcher were studied to provide a more mechanistic understanding of the role of environmental factors in regulating bio‐optical properties of phytoplankton. Specific attention was focused on quantities that are relevant for modeling of growth and photosynthesis. Characteristics including chlorophyll a (chl z)‐specific light absorption (a*ph(λ)), C:chl a ratio, and quantum yield for growth (φμ) varied as functions of temperature under conditions of excess light and nutrients. As temperature increased over the range examined (12°‐28°C), intracellular concentrations of chl a increased by a factor of 2 and a*ph(λ) values decreased by more than 50% at blue to green wavelengths. The lower values of a*ph(λ) were due to both a decrease in the abundance of accessory pigments relative to chl a and an increase in pigment package effects arising from higher intracellular pigment concentrations. Intracellular pigment concentration increased as a consequence of higher cellular pigment quotas combined with lower cell volume. At high growth temperatures, slightly more light was absorbed on a per‐cell‐C basis, but the dramatic increases in growth rate from μ= 0.5 d−1 at 12° C to μ= 2.2 d−1 at 28°C were primarily due to an increase in φμ (0.015–0.041 mol C (mol quanta)−1). By comparison with previous work on this species, we conclude the effects of temperature on a*ph(λ) and φμ are comparable to those observed for light and nutrient limitation. Patterns of variability in a*ph(λ)and φμ as a function of growth rate at different temperatures are similar to those previously documented for this species grown at the same irradiance but under a range of nitrogen‐limited conditions. These results are discussed in the context of implications for bio‐optical modeling of aquatic primary production by phytoplankton.
PROGRESSION OF SPERMATIAL NUCLEAR DIVISION REQUIRES CALCIUM INFLUX DURING FERTILIZATION OF THE RED ALGA PALMARIA SP.1
Authors: Mine Ichiro , Tatewaki Masakazu
Published: October 2004

During fertilization of the red alga Palmaria sp. (Palmariales), the prophase‐arrested nucleus of the uninucleate spermatium resumes its division after direct attachment of the spermatium to the trichogyne of a carpogonium. Treatments that reduce Ca2+ influx inhibit the progression of spermatial nuclear division. The ratio of the number of spermatia released from prophase arrest (those in meta‐phase to binucleate stages) to the total spermatia attached to trichogynes was significantly reduced by incubating the spermatia in the culture solution having low Ca2+ concentration. Similar inhibition was observed by addition of either inorganic (La3+ and Co2+) or organic (nifedipine and tetramethrin) Ca2+ channel inhibitors to the culture solution containing 10 mM Ca2+. These results indicate that the prophase/metaphase transition of spermatial nuclear division requires an influx of Ca2+ and suggest that Ca2+ acts as a second messenger to the mechanical or chemical stimulus that initiates mitotic progression of spermatia in this alga.
RESTRICTION FRAGMENT LENGTH POLYMORPHISM OF RIBOSOMAL DNA INTERNAL TRANSCRIBED SPACER AND 5.8S REGIONS IN JAPANESE ALEXANDRIUM SPECIES (DINOPHYCEAE)1
Authors: Adachi Masao , Sako Yoshihiko , Ishida Yuzaburo
Published: October 2004

The 5.8S ribosomal RNA (rDNA) gene and flanking internal transcribed spacers (ITS1 and ITS2)from 9 isolates of Alexandrium catenella (Whedon and Kofoid) Taylor, 11 isolates of A. tamarense (Lebour) Taylor, and single isolates of A. affine (Inoue et Fukuyo) Balech, A. insuetum Balech, and A. pseudogonyaulax (Biecheler) Horiguchi ex Yuki et Fukuyo comb. nov. from various locations in Japan were amplified using the polymerase chain reaction (PCR) and subjected to restriction fragment‐length polymorphism (RFLP) analysis. PCR products from all strains were approximately 610 bp, inclusive of a limited region of the 18S and 28S rRNA coding regions. RFLP analysis using four restriction enzymes revealed six distinct classes of rDNA (“ITS types”). Restriction patterns of A. catenella were uniform at the intra‐specific level and clearly distinguishable from those of A. tamarense. The patterns associated with A. tamarense (“tamarense group”) were also uniform except for one strain, WKS‐1. Some restriction fragments from WKS‐1 were in common with those of A. catenella or A. tamarense, whereas some were distinct from all Alexandrium species tested. Alexandrium affine, A. insuetum, and A. pseudogonyaulax carry unique ITS types. The ITSs of the “tamarense group” exhibit sequence heterogeneity. In contrast, the ITSs of all other isolates (including WKS‐1) appear homogeneous. RFLP analysis of the 5.8S rDNA and flanking ITSs regions from Alexandrium species reveals useful taxonomic and genetic markers at the species and/or population levels.
MOLECULAR PHYLOGENETIC ANALYSIS OF rbcL IN THE PRYMNESIOPHYTA1
Authors: Fujiwara Shoko , Sawada Mitsuhiro , Someya Junichiro , Minaka Nobuhiro , Kawachi Masanobu , Inouye Isao
Published: October 2004

The nucleotide sequences of rbcL genes encoding the large subunit of ribulose‐1,5‐bisphosphate carboxylase/oxygenase (Rubisco) were determined from six species of Prymnesiophyta to clarify their phylogenetic relationships. Molecular phylogenetic trees were constructed using PAUP (Phylogenetic Analysis Using Parsimony). These analyses suggest that the Prymnesiophyta, except for the Pavlovales, area relatively stable monophyletic group. Pleurochrysis carterae, included in the Isochrysidales, is a sister species of a monophyletic group consisting of other members of the Isochrysidales, Gephyrocapsa oceanica and Emiliania huxleyi, members of the Coccosphaerales, Calyptrosphaera sphaeroidea and Umbilicosphaera sibogae var. foliosa, and a member of the Prymnesiales, Chrysochromulina hirta. The nucleotide sequence of rbcL from G. oceanica was identical to that from E. huxleyi within the region examined. Our trees show that G. oceanica and E. huxleyi are more closely related to C. hirta than to U. sibogae, C. sphaeroidea, and P. carterae. These results suggest that orders in the Prymnesiophyceae, including the above‐mentioned genera, should be redefined.
CHARACTERIZATION OF OCEANIC PHOTOSYNTHETIC PICOEUKARYOTES BY FLOW CYTOMETRY1
Authors: Simon Nathalie , Barlow Raymond G. , Marie Dominique , Partensky Frédéric , Vaulot Daniel
Published: October 2004

To interpret flow cytometric data that are routinely obtained on natural oceanic communities, 23 strains of photosynthetic picoeukaryotes belonging to four classes (Prasinophyceae, Chlorophyceae, Pelagophyceae, and Prymnesiophyceae) and six pigment types were investigated for their light scattering in the forward and right‐angle directions, chlorophyll fluorescence, and DNA content as measured by flow cytometry. Cell she was assessed by Coulter counter, and pigment composition was measured by reverse‐phase high‐performance liquid chromatography. The size and GC% of the nuclear genome of cultured picoeukaryotes was measured from the fluorescence of DNA‐specific dyes. Using these two parameters, we could discriminate species within pigment groups. DNA staining of preserved natural samples may also prove useful in discriminating cooccurring populations in situ as long as the communities are not too complex. Using the relationships that we established between size and light‐scattering properties of the cells, we estimated equivalent diameters of picoeukaryotes in natural populations to be between 1.3 and 2 μm. Chlorophyll a content was between 6 and 16 fg·cel−1 as calculated from relationships that we established between chlorophyll a content and red fluorescence of the cultured strains. With respect to size, chlorophyll a content, and pigment composition, Pelagomonas sp. strains (Pelagophyceae) appeared to be the most representative of the natural communities in subtropical ocean waters. In contrast, green coccoid strains, which often outcompete other strains in culture, might only be minor contributors to these communities.
TRANSIENT AMMONIUM UPTAKE IN THE MACROALGA ULVA LACTUCA (CHLOROPHYTA): NATURE, REGULATION, AND THE CONSEQUENCES FOR CHOICE OF MEASURING TECHNIQUE1
Authors: Pedersen Morten Foldager
Published: October 2004

The nature of transient ammonium uptake by the macroalga Ulva lactuca L. was studied from the depletion of ammonium after single additions of ammonium to batch cultures. The experiments were carried out by the application of two different experimental setups: the “multiple flask” and the “perturbation” techniques. Uptake rate was nonlinear with time, and three distinct, succeeding phases of uptake were identified: 1) “surge” uptake, i.e. transiently enhanced uptake that lasted for a few hours only, followed by 2) “internally” controlled uptake, a relatively constant phase occurring at high substrate concentrations, and finally 3) the “externally” controlled uptake phase, which was substrate‐dependent and occurred at low substrate concentrations. Surge uptake occurred over a broad range of substrate concentrations but was concentration‐dependent and, so, equalled externally controlled uptake rates at substrate concentrations below 3–10 μM. The transient nature of ammonium uptake rate seemed related to rapid changes in small intracellular pools of inorganic nitrogen or amino acids rather than to changes in total N content of the algae. The transient nature of ammonium uptake has important implications for the measurement of uptake rates when either of the two standard methods, the multiple flask and the perturbation technique, are used, and I recommend that a combination of the two methods be used for future uptake experiments.
PHYLOGENY OF THE GENUS PYRAMIMONAS (PRASINOPHYCEAE, CHLOROPHYTA) INFERRED FROM THE rbcL GENE1
Authors: Daugbjerg Niels , Moestrup Øjvind , Arctander Peter
Published: October 2004

A 1089‐basepair fragment (approx. 75%) of the large subunit of the chloroplast‐encoded gene, ribulose‐1,5‐bis‐phosphate carboxylase/oxygenase (rbcL), was sequenced from 16 species of the genus Pyramimonas Schmarda. Electron microscopic and biochemical studies of Pyramimonas, one of the most morphologically diverse genera within the potential sister groups to the chlorophyll a‐ and b‐containing plants, suggest that this genus consists of at least four separate subgenera. Using the homologous sequence of rbcL from Cymbomonas tetramitiformis Schiller (Halosphaeraceae) as an outgroup and applying the maximum likelihood method, we show that the inferred topology is congruent with traditional delimitations of the taxa based on observations of periplast, internal ultrastructure, and biochemical features. A bootstrap analysis also supports division at the subgeneric level; however, the low bootstrap support associated with the deep nodes precludes resolution of these branches. A maximum likelihood relative rate test revealed that the rbcL gene in these single‐celled green flagellates has a heterogeneous rate of substitution. The rbcL gene in species of the subgenus Pyramimonas has evolved at an accelerated rate relative to that of congenerics.
ISOLATION AND REGENERATION OF HAPLOID PROTOPLASTS FROM BANGIA ATROPURPUREA (RHODOPHYTA) WITH MARINE BACTERIAL ENZYMES1
Authors: Araki Toshiyoshi , Hayakawa Michio , Tamaru Yutaka , Yoshimatsu Keiji , Morishita Tatsuo
Published: October 2004

Three kinds of enzymes, agarase, β‐1,4‐mannanase, and β‐1,3‐xylanase, required for isolation of protoplasts from the red alga Bangia atropurpurea (Roth) C. Ag. were prepared from bacterial culture fluids of Vibrio sp. PO‐303, Vibrio sp. MA‐138, and Alcaligenes sp. XY‐234, respectively, isolated from the sea environment. The optimal pH of all enzymes was around 7.5. Suitable conditions for protoplast isolation from B. atropurpurea were examined. The pretreatment of the fronds with pa‐pain solution (20 mM Mes buffer, pH 7.5, containing 2% papain and 0.5 M mannitol) contributed to successful protoplast isolation. When razor‐cut fragments of the fronds (about 200 mg in fresh weight) immersed in 20 mM Mes buffer, 7.5, containing 0.5 M mannitol and one unit each of agarase, β‐1,4‐mannanase, and β‐1,3‐xylanase were incubated at 22°C for 90 min with gentle agitation, 5.7 × 106 protoplasts were released from them. Many protoplasts regenerated into fronds of regular or irregular shape.
THE ECOLOGY OFNOSTOC
Authors: Dodds Walter K. , Gudder Dolly A. , Mollenhauer Dieter
Published: October 2004

Nostocis a genus of filamentous cyanobacteria that can form macroscopic or microscopic colonies and is common in both terrestrial and aquatic habitats. Much of the success ofNostocin terrestrial habitats is related to its ability to remain desiccated for months or years and fully recover metabolic activity within hours to days after re‐hydration with liquid water. Nostoccan also withstand repeated cycles of freezing and thawing and, thus, is an important component of extreme terrestrial habitats in the Arctic and Antarctic. The ability to fix atmospheric N2can provide an advantage in nitrogen‐poor environments. Nostocalso has the ability to screen damaging ultraviolet light in terrestrial and shallow benthic habitats. The genus potentially could be important in paddy rice culture because it fixes nitrogen that may later be released and used by plants; it also may play a role in soil formation and may increase nitrogen input to natural aquatic and terrestrial ecosystems. The abilities to survive in terrestrial habitats and fix N2are important in symbiotic interactions with fungi (lichens), liverworts, hornworts, mosses, ferns, cycads, and the angiospermGunnera. Nostocis somewhat resistant to predation; this probably is related to production of large amounts of sheath material, synthesis of microcystin‐like toxins by some strains, and formation of colonies that are too large for many algivores to consume. Some organisms can subsist onNostoc,although it may not be a preferred food source. Lytic cyanophages also infectNostoc,but little is known about population control ofNostocin its natural environment, Late Precambrian fossils resemblingNostochave been described, andNostocpossibly has been an important component of many terrestrial and aquatic communities since that time.
RESPONSE OF MICROALGAL EPIPHYTE COMMUNITIES TO NITRATE ENRICHMENT IN AN EELGRASS (ZOSTERA MARINA) MEADOW1
Authors: Coleman Virginia L. , Burkholder JoAnn M.
Published: October 2004

The community structure and productivity of epiphytic microalgae on field populations of eelgrass (Zostera marina L.) from a high flow regime were characterized under water‐column nitrate enrichment over a 30–d period during the autumn growing season for the macrophyte. Epiphyte communities in replicate low‐nitrogen sites (LOW‐N, median water‐column nitrate concentrations below detection) were compared to communities in replicate N‐enriched sites wherein nitrate was leached from clay pots filled with enriched agar (N‐ENRICH, median concentration ca. 6 μM NO3−‐N; pots replaced at 8– to 12–d intervals). In experimental chambers, total epiphyte community productivity as 14C‐bicarbonate uptake was determined from short‐term (3–h) laboratory assays. Track light microscope‐autoradiography enabled estimates of species‐specific productivity for abundant algal taxa. After 6 d in the LOW‐N and N‐ENRICH communities, the crustose adnate red alga Sahlingia subintegra (Rosenvinge) Kornmann was dominant in terms of cell number and codominant in biovolume. Photosynthetic dinoflagellates, not previously reported as abundant in eelgrass epiphyte communities, were dominant in biovolume contribution after both 6 and 30 d in LOW‐N communities. Nitrate enrichment stimulated the adnate monoraphid diatom Cocconeis placentula Ehr. but apparently inhibited dinoflagellates and the diatom Melosira sp. Total productivity of the epiphyte communities remained comparable in both the LOW‐N and N‐ENRICH sites. Shifts in community structure and species‐specific productivity, however, indicated a controlling influence of nitrate supply on microalgal epiphytes in the field eelgrass community.
IMPORTANCE OF RESTING STAGES IN DIATOM SEASONAL SUCCESSION1
Authors: McQuoid Melissa R. , Hobson Louis A.
Published: October 2004

The role of environmental factors in seasonal succession of six clones of marine diatoms was examined by testing effects of various combinations of temperature (5°, 10°, 15°, 20°C) and photoperiod (10, 12, 14, 16 h) on time to germination of resting stages and subsequent vegetative cell division rates. Resting stages were induced in batch cultures using a low nutrient medium and a cold, dark period. A three‐factor ANOVA showed that species, temperature, daylength, and their interactions signficantly (P =0.0001) injuenced germination time and division rate. Resting stages of Chaetoceros similis Cleve and Odontella aurita (Lyngbye) Agardh were most successful in producing populations of cells on warm, long days (20°C/16 h). Chaetoceros didymus Ehrenberg and C. cinctus Gran were most successful under more moderate conditions (15°C/14 h). Resting stages of Ditylum bright‐wellii (West) Grunow germinated and cells divided rapidly under all conditions. No consistent pattern was evident with Thalassiosira rotula Meunier. We compared results of the laboratory study with environmental conditions prevailing during the presence of these species in a British Columbia fjord. Favorable growth conditions determined for C. didymus, D. brightwellii, and T. rotula were similar to conditions present when these species were commonly found in the fjord.
PHYSIOLOGICAL PROFILES OF SYNECHOCOCCUS (CYANOPHYCEAE) IN IRON‐LIMITING CONTINUOUS CULTURES1
Authors: Wilhelm Steven W. , Trick Charles G.
Published: October 2004

We examined the physiology and biochemistry associated with the iron‐limited continuous culture of the halotolerant cyanobacterium Synechococcus PCC 7002. Biomass production, photosynthetic pigment levels, photosynthetic efficiency, and the production of hydroxamate‐ and catechol‐type siderophores are reported for cells grown over a range of available iron concentrations. The relationship between the yield of Synechococcus PCC 7002 in iron‐limited chemostats and the concentration of available iron was not linear. Synechococcus PCC 7002 expressed an inducible physiological response that led to alterations either in the cellular iron quotient or, more likely, in levels of available iron due to induced iron‐scavenging processes. During iron limitation these cyanobacteria produced components consistent with the activation of a high‐affinity iron transport system; both hydroxamate‐ and catechol‐type siderophores were detected. Iron‐limited Synechococcus PCC 7002 also reduced CO2 fixation rates from luxury levels to a rate that matched the cellular growth rate, presenting interesting implications for oceanic carbon flux models.
RELATIONSHIPS BETWEEN NITRATE REDUCTASE ACTIVITY AND RATES OF GROWTH AND NITRATE INCORPORATION UNDER STEADY‐STATE LIGHT OR NITRATE LIMITATION IN THE MARINE DIATOM THALASSIOSIRA PSEUDONANA (BACILLARIOPHYCEAE)1
Authors: Berges John A. , Harrison Paul J.
Published: October 2004

Although activity of the enzyme nitrate reductase (NR) can potentially be used to predict the rate of nitrate incorporation in field assemblages of marine phytoplankton, application of this index has met with little success because the relationship between the two rates is not well established under steady‐state conditions. To provide a basis for using NR activity measurements, the relationships among NR activity, growth rate, cell composition, and nitrate incorporation rate were examined in cultures of Thalassiosira pseudonana (Hustedt)Hasle and Heimdal, growing a) under steady‐state light limitation, b) during transitions between low and high irradiance (15 or 90 μmol quanta.m−2.s−1), and c) under steady‐state nitrate limitation. Using a modified assay for NR involving additions of bovine serum albumin to stabilize enzyme activity, NR activity in light‐limited cultures was positively and quantitatively related to calculated rates of nitrate incorporation, even in cultures that were apparently starved of selenium. During transitions in irradiance, growth rates acclimated to new conditions within 1 day; through the transition, the relationship between NR activity and nitrate incorporation rate remained quantitative. In nitrate‐limited chemostat cultures, NR activity was positively correlated with growth rate and with nitrate incorporation rates, but the relationship was not quantitative. NR activity exceeded nitrate incorporation rates at lower growth rates (<25% of nutrient‐replete growth rates), but chemostats operating at such low dilution rates may not represent ecologically relevant conditions for marine diatoms. The strong relationship between NR activity and nitrate incorporation provides support for the idea that NR is rate‐limiting for nitrate incorporation or is closely coupled to the rate‐limiting step. In an effort to determine a suitable variable for scaling NR activity, relationships between different cell components and growth rate were examined. These relationships differed depending on the limiting factor. For example, under light limitation, cell volume and cell carbon content increased significantly with increased growth rate, while under nitrate limitation cell volume and carbon content decreased as growth rates increased. Despite the differences found between cell composition and growth rate under light and nitrate limitation, the relationships between NR activity scaled to different compositional variables and growth rate did not differ between the limitations. In field situations where cell numbers are not easily determined, scaling NR activity to particulate nitrogen content may be the best alternative. These results establish a strong basis for pursuing NR activity measurements as indices of nitrate incorporation in the field.
THE FLAGELLAR APPARATUS OF CHRYSOCHROMULINA SP. (PRYMNESIOPHYCEAE)1
Authors: Birkhead Monica , Pienaar Richard N.
Published: October 2004

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.
NEW ULTRASTRUCTURAL ASPECTS OF PYRENOIDS OF THE LICHEN PHOTOBIONTTREBOUXZA(MICROTHAMNIALES, CHLOROPHYTA)1
Authors: Ascaso Carmen , Valladares Fernando , de Los Rios Asuncióh
Published: October 2004

The pyrenoid structureof Trebouxia,a photobiont of two lichen species, Umbilicaria cinereorufescens (Schaer.) Frey andParmelia sulcataTaylor, was investigated. In both lichen species, the pyrenoid of the photobiont exhibited straight, unbranched, long or short tubules. In the first lichen species, multiple pyrenoids were observed occasionally, while in the second one, homogeneous masses, called protein bodies, appeared between the thylakoids. These protein bodies were previously observed in some other species of the family Umbilicariaceae. Serial sections from single pyrenoids showed that tubules of theImpressa‐type pyrenoid were closely associated with pyrenoglobuli. The three‐dimensional reconstruction of a complete chloroplast of aP. sulcataalgal cell showed that the protein bodies were spatially separate structures. Immunolocalization techniques to detect the presence of ribulose‐bisphosphate carboxylase (Rubisco) in the chloroplast showed that this enzyme was present primarily in the pyrenoid matrix. When protein bodies were present in the chloroplast, Rubisco appeared to be localized in these structures. The presence of pyrenoid satellites and protein bodies with reactivity to anti‐Rubisco may be related to the nutritional conditions of the thalli.