bluuebunny/crossref_metadata_2025_split huggingface dataset:
KINETICS OF BLUE‐LIGHT STIMULATION AND CIRCADIAN RHYTHMICITY OF LIGHT‐SATURATED PHOTOSYNTHESIS IN BROWN ALGAE: A SPECIES COMPARISON1
Authors: Schmid Rainer , Dring Matthew J. , Forster Rodney M. 
Published: October 2004

ABSTRACTThe time courses of photosynthetic rates in red light, with and without additional blue light, were investigated and compared in 20 species of brown algae. Species could be separated into two groups on the basis of the rhythmicity of their photosynthesis in red light and the kinetics of their responses to blue‐light pulses. One group, which consisted of members of the Ectocarpales, Chordariales, and Dictyosiphonales, was characterized by strong and persistent circadian rhythmicity in red light. The photosynthetic responses of these species to blue‐light pulses started within 10–30 s of the beginning of blue‐light treatment and mostly contained at least two distinct kinetic components. An early component, which reached a maximum about 5–10 min after the blue‐light pulse, was always detectable. Later components were seen as separate peaks or shoulders after an additional 10–20 min. The decay of the response in this group of species was mostly slow, with half‐lives of between 0.5 and 1.5 h. In the second group of species, consisting of members of the Dictyotales, Laminariales, and Fucales, photosynthesis in red light was usually non‐rhythmic, although circadian rhythms with a weak amplitude or of transient occurrence were observed in some plants of some species. The increase in photosynthesis in response to a blue‐light pulse was not detectable until 70–330 s after the start of blue‐light treatment, and the response itself had only a single component, with a maximum after about 10 min and half‐life of 10–20 min. The lengths of the lag‐phases were positively correlated with the times taken to reach the peak in this group, although the lag‐phases and the half lives sometimes varied with time in individual plants. Two members of the Sphacelariales (Sphacelaria, Cladostephus) did not fit into either of the two groups because their photosynthesis was rhythmic, but their responses had long lag‐phases, a single component, and moderately long half‐lives. The differences in the kinetics of the photosynthetic response to blue‐light pulses, which have been described for the two main groups of species, are thought to indicate that there are two distinct mechanisms by which light‐saturated photosynthesis responds to blue light in brown algae. Since in some species the maximal photosynthesis after a blue‐light pulse and the rate of photosynthesis in continuous blue light also varied in a circadian pattern, the response to blue light itself may be under circadian control.
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

ABSTRACTThree 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

ABSTRACT 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

ABSTRACTThe 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

ABSTRACTIndividuals 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

ABSTRACTWe 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

ABSTRACTThe 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

ABSTRACTThe 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

ABSTRACTCell 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

ABSTRACTThree 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

ABSTRACTWe 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

ABSTRACTTemperature 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

ABSTRACTWe 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

ABSTRACTThe 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.