bluuebunny/crossref_metadata_2025 huggingface dataset:
Anti‐LM1 antibodies in the sera of patients with Guillain‐Barré syndrome, Miller Fisher syndrome, and Motor Neuron Disease
Authors: Harukawa Hajime , Utsumi Hiroya , Asano Atsuko , Yoshino Hiide
Published: March 2003

Abstract  This study is designed to establish whether sialosylneolactotetraosylceramide (LM1), a major component of human peripheral nerve ganglioside, is a potential target antigen for the development of peripheral autoimmune neuropathies such as Guillain‐Barré syndrome (GBS) and Miller Fisher syndrome (MFS). Serum antibodies against LM1 in 116 patients with GBS, 56 patients with MFS, 88 patients with motor neuron disease (MND) and 60 normal control subjects were quantified using enzyme‐linked immunosorbent assay (ELISA). The presence of anti‐LM1 antibodies were confirmed using an immunostaining method on high‐performance thin‐layer chromatographic plates (HPTLC). Anti‐LM1 IgG antibodies were detected in 22% (25/116) of patients with GBS. The ratio of the demyelination type to the axonal type of GBS was approximately 3:1. Among the 25 anti‐LM1‐positive GBS patients, additional anti‐GM1 IgG antibodies were detected in 7 patients, 4 of whom possessed the axonal form of GBS. Anti‐LM1 antibodies were also detected in a significant portion of patients with MFS (20%, 11/56). In contrast, anti‐LM1 antibodies were detected in only 2% (2/88) of patients with MND, and 7% (4/60) of normal control subjects. The results of this study suggest that serum antibodies against LM1 may have a pathogenic role in the development of GBS and MFS.
Advanced glycation end products, their receptors and diabetic angiopathy
Authors: Wautier JL , Guillausseau PJ
Published: March 2003

The role of chronic hyperglycemia in the development of diabetic microvascular complications and in neuropathy has been clearly established by intervention studies. However, the biochemical or cellular links between elevated blood glucose levels, and the vascular lesions remain incompletely understood. This review focuses on the consequences of hyperglycemia on the formation of advanced glycation end‐products (AGEs), and on the role of AGEs and of their specific receptors (RAGE) in the functional and anatomical alterations of the vascular wall. AGEs are formed during the Mailiard reaction by the binding of aldoses on free NH2 groups of proteins, which, after a cascade of molecular rearrangements, result in molecules of brown color and specific fluorescence. Experimental studies have indicated that the binding of AGEs to RAGE activates cells, particularly monocytes and endothelial calls. Activated endothelial cells produce cytokines, and express adhesion molecules and tissue factor. The role of AGEs in increased oxidative stress, and in the functional alterations in vascular tone control observed in diabetes, in part related to a reduction in nitric oxide, is also discussed. The microvascular retinal, glomerular and nerve lesions induced by experimental diabetes in animals are prevented by an inhibitor of AGEs formation, aminoguanidine. The administration in diabetic animals of recombinant RAGE, which hinders AGEs‐RAGE interaction, prevents hyperpermeability and vascular lesions. These data suggest a central role of AGEs and RAGE in the development of chronic complications of diabetes.
THE KINETICS OF THE PHOTOACCLIMATION RESPONSE OF NANNOCHLOROPSIS SP. (EUSTIGMATOPHYCEAE): A STUDY OF CHANGES IN ULTRASTRUCTURE AND PSU DENSITY
Authors: Fisher Tamar , Berner Tamar , Iluz David , Dubinsky Zvy
Published: March 2003

In this study we report the kinetics of photoacclimation of the unicellular alga Nannochloropsis sp. grown under high light (HL), and subsequently transferred to low light (LL). We examined the changes in ultrastructural features, pigmentation, and photosynthetic parameters over short intervals until the LL steady state was reached. The ultrastructural changes were followed by quantitative morphometric measurements of transmission electron micrographs. We found that the increase in the relative volume of the chloroplast during acclimation to LL (twofold) was accompanied by an increase in number of stacks (twofold) and in the surface area of thylakoids per cell (2.5‐fold). The increase in photosynthetic unit (PSU) density was about 2.15‐fold. Maximal density was about 84 PSU·μm−2 in LL cells, and minimal density was 39 PSU·μm−2 in HL cells. The HL/LL ratio of the in vivo optical absorption cross‐section of PSU (σPSU) was 2.8, whereas in the in vivo optical absorption cross‐section of the cell (σcell), the trend of change was in the opposite direction: 1.7‐fold higher in LL‐acclimated cells than in HL‐acclimated cells. We propose a partial sequence of the photoacclimation processes based on our data and the derived rate constants.
COMPARISON OF DEVELOPMENT AND PHOTOSYNTHETIC GROWTH FOR FILAMENT CLUMPS AND REGENERATED MICROPLANTLET CULTURES OF AGARDHIELLA SUBULATA (RHODOPHYTA, GIGARTINALES)
Authors: Huang Yao‐ming , Maliakal Sanjiv , Cheney Donald P. , Rorrer Gregory L.
Published: March 2003

Two axenic, in vitro liquid suspension cultures were established for Agardhiella subulata (C. Agardh) Kraft et Wynne, and their growth characteristics were compared. This study illustrated how reliable routes for the development of suspension cultures of macrophytic red algae of terete thallus morphology can be achieved for biotechnology applications. Undifferentiated filament clumps of 2–8 mm diameter were established by induction of callus‐like tissue from thallus explants, and lightly branched microplantlets of 2–10 mm length were established by regeneration of filament clumps. The filament clumps were susceptible to regeneration. Adventitious shoot formation was reliably induced from 40% to 70% of the filament clumps by gentle mixing at 100 rev min−1 on an orbital shaker. The specific growth rate of the microplantlets was higher than the filament clumps in nonagitated well plate culture (4%–6% per day for microplantlets vs. 2%–3% per day for filament clumps) at 24° C and 8–36 μmol photons·m−2·s−1 irradiance (10:14 h LD cycle) when grown on ASP12 artificial seawater medium at pH 8.6–8.9 with 20%–25% per day medium replacement. Oxygen evolution rate vs. irradiance measurements showed that relative to the filament clumps, microplantlets had a higher maximum specific oxygen evolution rate (Po,max= 0.181 ± 0.035 vs. 0.130 ± 0.023 mmol O2·g−1 dry cell mass·h−1), but comparable respiration rate (Qo= 0.040 ± 0.013 vs. 0.033 ± 0.017 mmol O2·g−1 dry cell mass·h−1), compensation point (Ic= 3.8 ± 2.4 vs. 5.7 ± 1.2 μmol photons·m−2·s−1), and light intensity at 63.2% of saturation (Ik= 17.5 ± 3.9 vs. 14.9 ± 2.6 μmol photons·m−2·s−1). The microplantlet culture was more suitable for suspension culture development than the filament clump culture because it was morphologically stable and exhibited higher growth rates.
ULTRAVIOLET SUNSCREENS IN GYMNODINIUM SANGUINEUM (DINOPHYCEAE): MYCOSPORINE‐LIKE AMINO ACIDS PROTECT AGAINST INHIBITION OF PHOTOSYNTHESIS
Authors: Neale Patrick J. , Banaszak Anastazia T. , Jarriel Catherine R.
Published: March 2003

Marine phytoplankton are sensitive to inhibition of photosynthesis by solar ultraviolet (UV) radiation, although sensitivity varies, depending on the growth environment. A mechanism suggested to increase resistance to UV inhibition is the accumulation of UV‐absorbing compounds, such as the mycosporine‐like amino acids (MAAs) found in many marine organisms. However, the effectiveness of these compounds as direct optical screens in microorganisms has remained unclear. The red‐tide dinoflagellate Gymnodinium sanguineum Hirasaka accumulates about 14‐fold more MAAs (per unit of chlorophyll) in high (76 W·m−2) than in low (15 W·m−2) growth irradiance. Biological weighting functions were estimated for UV inhibition of photosynthesis and showed that the high‐light‐grown cultures have lower sensitivity to UV radiation at wavelengths strongly absorbed by the MAAs. The time course of photosynthesis during exposure to UV radiation was measured using pulsed amplitude modulated (PAM) fluorometry and displayed a steady‐state level after 15 min of exposure, indicating active repair of damage to the photosynthetic apparatus. Repair was blocked in the presence of the antibiotic streptomycin, yet high‐light G. sanguineum remained less sensitive to UV radiation than did low‐light cultures. These experiments show that MAAs act as spectrally specific UV sunscreens in phytoplankton.
A REAPPRAISAL OF PORPHYRA AND BANGIA (BANGIOPHYCIDAE, RHODOPHYTA) IN THE NORTHEAST ATLANTIC BASED ON THE rbcL–rbcS INTERGENIC SPACER
Authors: Brodie Juliet , Hayes Paul K. , Barker Gary L. , Irvine Linda M. , Bartsch Inka
Published: March 2003

Sequence data of the rbcL–rbcS noncoding intergenic spacer of the plastid genome for 47 specimens of Porphyra and Bangia from the northeast Atlantic reveal that they fall into 11 distinct sequences: P. purpurea, P. dioica (includes a sample of P. “ochotensis” from Helgoland), P. amplissima (includes P. thulaea and British records of P. “miniata”), P. linearis, P. umbilicalis, P. “miniata”, B. atropurpurea s.l. from Denmark and B. atropurpurea s.l. from Wales, P. drachii, P. leucosticta (includes a British record of P. “miniata var. abyssicola”), and P. “insolita” (includes P. “yezoensis” from Helgoland). Of these, data obtained for P. purpurea, P. dioica, P. amplissima, P. linearis, P. umbilicalis, P. drachii, and P. leucosticta were based on type specimens or material compared with types. Comparison of sequence data for Porphyra spp. and Bangia atropurpurea s.l. (including B. fuscopurpurea, the type species of Bangia) confirms that the species are congeneric. The data also confirm that the number of layers that make up the Porphyra thallus are not taxonomically significant. Comparison of sequence data for species from the northeast Atlantic with those for material of two species from the Pacific reveals that the species fall into two distinct groupings: an Atlantic group, containing P. purpurea, P. dioica, P. amplissima, P. linearis, P. umbilicalis, P. “miniata”, and B. atropurpurea, and a Pacific group, containing P. “pseudolinearis”, P. drachii, P. leucosticta, P. “yezoensis” (including a sample of P. “tenera”), and P. “insolita” (including P. “yezoensis” from Helgoland). The possibility of alien species in the northeast Atlantic is discussed.
CONTRASTING LIFE HISTORIES AND DEMOGRAPHIES OF LAMINARIAN AND FUCOID ALGAE
Authors: Schiel D.R.
Published: March 2003

Many species of large brown algae co‐occur along similar shores and depths and seem to share similar ecological characteristics in terms of habitat‐formation, providing nursery and feeding habitats for reef fish, vertical structure of habitats within the water column and biomass production. However, the dominant species have very different life histories. Laminarians have a heteromorphic alternation of generations, while fucaleans have an animal‐like life history with more direct development. Despite these differences, there seems to be no obvious relationship between life history and ecological function. Laminarians and fucaleans seem generally to have very different demographies, with quite disparate features such as propagule size and number, early survival, growth rates, and densities of plants required for a closed canopy. Furthermore, few laminarians occur in the intertidal zone. Here, I will compare some species in these groups for which we know something about life history and ecology in New Zealand and the USA. Although it is necessary to understand life histories of individual species to understand their demography and ecological functions, this is not sufficient in itself to predict such roles and functions.
ACCLIMATION OF PROROCENTRUM MINIMUM (DINOPHYCEAE) TO PROLONGED DARKNESS BY USE OF AN ALTERNATIVE CARBON SOURCE FROM TRIACYLGLYCERIDES AND GALACTOLIPIDS
Authors: Manoharan Kumariah , Lee Taek Kyun , Cha Jea Myung , Kim Jeong Ha , Lee Woo Sung , Chang Man , Park Chul Won , Cho Jin Ha
Published: March 2003

The dinoflagellate Prorocentrum minimum (Pavillard) Schiller is known to be a major bloom‐causing microalga in the southern ocean of the Korean peninsula. The acclimation of this alga to darkness for 10 days was investigated by analyzing the content of various lipids, such as phospholipid (PL), galactolipid (GL), and triacylglyceride (TAG). Actively growing cultures of the alga under normal growth conditions (14:10 h LD [light:dark] cycle) were transferred to a growth chamber under conditions of no light and no carbon sources in the medium, and the culture was continued for another 10 days. The results showed that the content of TAG and GL decreased gradually during dark incubation, whereas the total PL content changed little; PC, PE, and PG decreased; and PS, PA, and PI increased. An increase in the activity of β‐oxidation and isocitrate lyase (ICL, a glyoxylate cycle enzyme) paralleled the decrease of TAG and GL. These observations strongly suggested that TAG and GL were utilized as alternative carbon sources by the cells under the prolonged dark cultivation. Light treatment of the cells cultivated in the dark for 10 days allowed them to attain the lipid composition that was observed in cells grown in light. These results strongly suggested that the cells maintained their metabolic integrity without unrecoverable cellular damages or cell death during 10 days of dark cultivation.
A TEST OF TWO POSSIBLE MECHANISMS FOR PHOTOTACTIC STEERING IN VOLVOX CARTERI (CHLOROPHYCEAE)
Authors: Hoops Harold J. , Brighton Mark C. , Stickles Scott M. , Clement Philip R.
Published: March 2003

We tested two competing models that could explain how differential flagellar activity leads to phototactic turning in spheroids of Volvox carteri f. weismannia (Powers) Iyengar. In one model, turning results from the flagella of anterior cells in the lighted and shadowed hemispheres beating at different frequencies. In a competing model, turning results from a change in beat direction in these flagella. Both models successfully explain phototactic steering under constant illumination, but they make different predictions when colonies are exposed to abrupt changes in light intensity. If turning is due to control of flagellar beat frequency, both progression and rotation rates will change in the same direction and with similar magnitudes. If spheroid turning is due to a change in flagellar beat direction, a decreased rate of progression will accompany an increased rate of rotation and vice versa. We used video‐microscopy to observe the behavior of positively phototactic V. carteri spheroids exposed to 10× step‐up and step‐down stimuli. After a step‐up stimulus, spheroids slow their progression and rotation by equal amounts. No significant changes are reported in these parameters after the reciprocal step‐down response. These observations are consistent with the variable flagellar frequency model and inconsistent with the variable flagellar direction model for phototactic turning. Switching the direction of light stimulus by 180° results in reorientation of positively phototactic spheroids. The kinetics of this reorientation did not precisely match the predictions of either model.
CIRCADIAN RHYTHM IN GROWTH AND DEATH OF ANABAENA FLOS‐AQUAE (CYANOBACTERIA)
Authors: Lee Dae‐Young , Rhee G‐Yull
Published: March 2003

Circadian periodicity in cell division and death was investigated in the cyanobacterium Anabaena flos‐aquae (Lyngb.) Bréb in a phosphorus (P)‐limited, N2‐fixing chemostat culture. When entrained under 12:12 h LD cycles, not only cell division but also cell death showed a clear circadian rhythm in this filamentous cyanobacterium. The rhythm persisted under continuous light and was temperature compensated. Circadian rhythm was clearly observed in the steady‐state cell number and instantaneous growth rate, μ(t), which reached a maximum at about 2 h before sunset and a minimum at about 2 h before sunrise. The number of dead cells and the instantaneous death rate γ(t) also showed a circadian periodicity; the peak of γ(t) occurred approximately 8 h before that of μ(t). Therefore, cell growth and death in A. flos‐aquae appear to be under the control of circadian clocks, and thus it seems that their death is programmed cell death.
BIOLOGICAL AND CHEMICAL CHARACTERISTICS OF THE GIANT DIATOM ETHMODISCUS (BACILLARIOPHYCEAE) IN THE CENTRAL NORTH PACIFIC GYRE
Authors: Villareal Tracy A. , Joseph Leanne , Brzezinski Mark A. , Shipe Rebecca F. , Lipschultz Fredric , Altabet Mark A.
Published: March 2003

Cells of the giant diatom Ethmodiscus Castr. gathered from the upper 15 m were examined for O2 evolution, nitrate reductase activity (NRA), C and N composition, internal NO concentrations, , and 15NO, 15NH , and 32Si uptake in a series of cruises in the central N. Pacific gyre. The δ15N (2.56–5.09 ‰), internal NO concentrations (0.0– 11.5 mM NO−), and NRA (6.7 ± 4.7 × 10−4μM NO cell −1·h−1) were consistent with recent exposure to elevated nitrate concentrations and utilization of deep NO as a primary N source. These results are similar to other diatoms that migrate vertically to the nutricline as part of their life cycle. Rate measures (Si[OH]4 uptake, NRA, and O2 evolution) indicated surface doubling times from 45 h to 75 h. Both NO and NH uptake in surface waters were low and inadequate to supply N needs at surface NO and NH concentrations. Our results suggest a partitioning in nutrient acquisition, with N acquired at depth and C and Si acquired at the surface. Doubling rates were two to three times higher than predicted from cell volume and C content models. These data are consistent with the observed elemental content being lower than expected because of the dominance of cell volume by the vacuole. Our calculations suggest that Ethmodiscus contributes little to the biogeochemistry of the upper water column via upward nutrient transport. Although reported as a paleo‐upwelling indicator, thisevidence suggests that Ethmodiscus has adapted to the nutrient‐poor open ocean by a vertical migration strategy and has biological characteristics inconsistent with a upwelling indicator.
TOWARD AN ASSESSMENT ON THE TAXONOMY OF DINOFLAGELLATES THAT PRODUCE CALCAREOUS CYSTS (CALCIODINELLOIDEAE, DINOPHYCEAE): A MORPHOLOGICAL AND MOLECULAR APPROACH
Authors: D’Onofrio Giuseppe , Marino Donato , Bianco Luigi , Busico Elisabetta , Montresor Marina
Published: March 2003

In recent years an unified classification system for both fossil cysts and extant dinoflagellate species has been proposed. This classification has prompted investigations aimed at testing the phylogenetic validity of the distinctive morphological characters of both vegetative cells and cysts. We have focused on a group of dinoflagellates that produce calcareous resting cysts, which are abundant in marine neritic and oceanic waters and form wide fossil deposits. Extant species are included in the genera Scrippsiella, Ensiculifera, and “Pentapharsodinium” (subfamily Calciodinelloideae), which are distinguished by the number and/or shape of the cingular plates of their planktonic vegetative stages. On the other hand, the classification of fossil cysts is based on the morphology of the calcareous covering and on the orientation of crystals. In this study we combine the information derived from morphological traits of both motile stages and cysts with that obtained from nucleotide sequence analysis of the ribosomal DNA internal transcribed spacers (ITS). We also describe the vegetative cell produced by the calcareous cyst Calcigonellum infula and a new variety, Scrippsiella trochoidea var. aciculifera var. nov. Molecular analyses confirm the monophyletic origin of the genus Scrippsiella, whereas the “Pentapharsodinium” and Ensiculifera species are grouped together in another monophyletic cluster. The coupled morphological and molecular approach supports the taxonomic value of some of the characters of the planktonic stage, such as the cingular plate number. On the other hand, it questions the validity of other morphological characters of both vegetative and encysted stages. Our data provide a phylogenetic classification of these dinoflagellates; however, they also open a debate that would imply a redefinition of the characters to be used for the circumscription of the subfamily Calciodinelloideae.
INORGANIC CARBON LIMITATION, EXOFACIAL CARBONIC ANHYDRASE ACTIVITY, AND PLASMA MEMBRANE REDOX ACTIVITY IN MARINE PHYTOPLANKTON SPECIES
Authors: Nimer Nabil A. , Ling Miao Xiao , Brownlee Colin , Merrett Michael J.
Published: March 2003

In the marine phytoplankton species tested, a possible link between exofacial ferricyanide reduction at the plasma membrane of intact cells, inorganic carbon status of the cells, and extracellular carbonic anhydrase (CA) activity is proposed. In species with no extracellular CA activity under carbon‐limited or carbon‐replete conditions, barely detectable ferricyanide reduction was observed. Species in which extracellular CA was only detected under carbon‐limited conditions showed high rates of exofacial ferricyanide reduction, as shown previously for Skeletonema costatum. Immunological analysis has demonstrated that the CA protein was present in both carbon‐limited and carbon‐replete cells, even though the CA activity could only be detected when inorganic carbon was limiting. Incubation of the inactive extracellular CA protein from carbon‐replete cells with DTT caused activation of the enzyme. It is proposed that CA limitation in the light promotes proton extrusion and increased plasma membrane redox activity, which result in the protonation and activation of the extracellular CA.
MIXOTROPHY AND NITROGEN UPTAKE BY PFIESTERIA PISCICIDA (DINOPHYCEAE)
Authors: Lewitus Alan J. , Willis Bonnie M. , Hayes Kenneth C. , Burkholder JoAnn M. , Glasgow Jr. Howard B. , Glibert Patricia M. , Burke Marianne K.
Published: March 2003

The nutritional versatility of dinoflagellates is a complicating factor in identifying potential links between nutrient enrichment and the proliferation of harmful algal blooms. For example, although dinoflagellates associated with harmful algal blooms (e.g. red tides) are generally considered to be phototrophic and use inorganic nutrients such as nitrate or phosphate, many of these species also have pronounced heterotrophic capabilities either as osmotrophs or phagotrophs. Recently, the widespread occurrence of the heterotrophic toxic dinoflagellate, Pfiesteria piscicida Steidinger et Burkholder, has been documented in turbid estuarine waters. Pfiesteria piscicida has a relatively proficient grazing ability, but also has an ability to function as a phototroph by acquiring chloroplasts from algal prey, a process termed kleptoplastidy. We tested the ability of kleptoplastidic P. piscicida to take up 15N‐labeled NH, NO, urea, or glutamate. The photosynthetic activity of these cultures was verified, in part, by use of the fluorochrome, primulin, which indicated a positive relationship between photosynthetic starch production and growth irradiance. All four N substrates were taken up by P. piscicida, and the highest uptake rates were in the range cited for phytoplankton and were similar to N uptake estimates for phagotrophic P. piscicida. The demonstration of direct nutrient acquisition by kleptoplastidic P. piscicida suggests that the response of the dinoflagellate to nutrient enrichment is complex, and that the specific pathway of nutrient stimulation (e.g. indirect stimulation through enhancement of phytoplankton prey abundance vs. direct stimulation by saprotrophic nutrient uptake) may depend on P. piscicida’s nutritional state (phagotrophy vs. phototrophy).
Phylogenetic analyses of various euglenoid taxa (euglenozoa) based on 18s rdna sequence data
Authors: Preisfeld Angelika , Berger Silke , Busse Ingo , Liller Susanne , Ruppel Hans Georg
Published: March 2003

18S rRNA genes (SSU rDNA) of five newly sequenced species were used as molecular markers to infer phylogenetic relationships within the euglenoids. Two members of the order Euglenales (Lepocinclis ovata Playfair, Phacus similis Christen), two of the order Eutreptiales (Distigma proteus Ehrenberg,, D. curvata Pringsheim) and Gyropaigne lefévrei Bourelly et Georges of the order Rhabdomonadales were used in parsimony, maximum likelihood, and distance analyses. All trees derived from SSU rRNA data strongly supported the monophyletic origin of the Euglenozoa, with kinetoplastids as sister clade to the euglenoids and Petalomonas cantuscygni Cann et Pennick diverging at the base of the monophyletic euglenoid lineage. The data also supported the theory that phagotrophic euglenoids arose prior to osmotrophs and phototrophs. A lineage of Peranema trichophorum Ehrenberg and all sequenced Euglenales formed a sister clade to the osmotrophs. This suggests that the evolution of phototrophy within the euglenoids radiated from a single event.
Nostoc verrucosum (cyanobacteria) colonized by a chironomid larva in a mediterranean stream (Note)†
Authors: Sabater Sergi , Muñoz Isabel
Published: March 2003

Colonization of Nostoc verrucosum Vaucher by chironomid larvae (Cricotopus sp.) has been observed in a mountain stream in northeastern Spain. Colonies containing the midge were globose, 1.4 mm thick, 3.1 mm long, and 2.4 mm wide. The form of the pads was slightly compressed, arranged in parallel to or slightly oblique to the stream flow. The midge–Nostoc association shows a more globose growth form than that described for N. parmelioides Kütz. (ear‐like forms). Inhabited pads were usually located in the upper part of the colonies, and the midge did not contact the substratum. The midge was therefore unable to secure the colony to the substratum. The morphology and dimensions of the Nostoc cells in pads with Cricotopus were very similar to those without the midge. The globose growth form of the colonized pads does not suggest any special advantage with respect to chironomid‐free N. verrucosum concerning flow preferences and light exposure in the stream habitat.
MORPHOLOGY OF THE MARINE DIATOM NITZSCHIA NAVIS‐VARINGICA, SP. NOV. (BACILLARIOPHYCEAE), ANOTHER PRODUCER OF THE NEUROTOXIN DOMOIC ACID
Authors: Lundholm Nina , Jvind Moestrup Ø
Published: March 2003

A new marine diatom, Nitzschia navis‐varingica, sp. nov., isolated from Vietnamese waters, is described by light, transmission, and scanning electron microscopy, including thin sectioning. The new species has been found to produce the neurotoxin domoic acid (DA), better known from several species of Pseudo‐nitzschia Peragallo and one species of Amphora Ehrenberg. Production of DA is therefore more widespread among diatoms than previously thought. Taxonomically, the genus Nitzschia Hassall is exceptionally difficult, with about 900 described taxa. Grunow (in Cleve and Grunow 1880 divided the genus into 24 sections, and this system is still used with modifications. Nitzschia navis‐varingica, sp. nov. fits best into a group of sections that includes Dubiae, Bilobatae, most of the Lanceolatae, and Lineares, all sensu Grunow, as the cell is slightly indented in the middle in girdle view and has a moderately eccentric raphe and a weak longitudinal fold on the valve. Many species within these sections have features similar to N. navis‐varingica, but no species seems to be identical. Because both Pseudo‐nitzschia and Nitzschia belong to the family Bacillariaceae, it seems reasonable to look for further producers of DA in this family, including freshwater species, which mainly comprise species within the sections Dubiae, Bilobatae, Lanceolatae, and Lineares.
FLOW CYTOMETRY AND THE SINGLE CELL IN PHYCOLOGY
Authors: Collier Jackie L.
Published: March 2003

Flow cytometers measure light scattering and fluorescence characteristics from individual particles in a fluid stream as they cross one or more light beams at rates of up to thousands of events per second. Flow cytometrically detectable optical signals may arise naturally from algae, reflecting cell size, structure, and endogenous pigmentation, or may be generated by fluorescent stains that report the presence of otherwise undetected cellular constituents. Some flow cytometers can physically sort particles with desired optical characteristics out of the flow stream and collect them for subsequent culture or other analyses. The statistically rigorous, cell‐level perspective provided by flow cytometry has been advantageous in experimental investigations of phycological problems, such as the regulation of cell cycle progression. The capacity of flow cytometry to measure large numbers of cells in large numbers of samples rapidly and quantitatively has been used extensively by biological oceanographers to define the distributions and dynamics of marine picophytoplankton. Recent work has shown that flow cytometry can be used to elucidate relationships between the optical properties of individual cells and the bulk optical properties of the water they live in, and thereby may provide an explicit link between algal physiology and global biogeochemistry. Unfortunately, commercially available flow cytometers that are optimized for biomedical applications have a limited capacity to analyze larger phytoplankton. To circumvent these limitations, many investigators are developing flow cytometers specifically designed for analyzing the broad range of sizes, shapes, and pigments found among algae. These new instruments can perform some novel measurements, including simple fluorescence excitation spectra, detailed angular scattering measurements, and in‐flow digital imaging. The growing accessibility and power of flow cytometers may allow the technology to be applied to a wider array of problems in phycology, including investigations of nonplanktonic and multicellular algae, but also presents new challenges for effectively analyzing the large quantity of multiparameter data produced. Ultimately, the detection of molecular probes by flow cytometry may allow single‐cell taxonomic and physiological information to be garnered for a variety of algae, both in culture and in nature.
LIBERATION OF 5,8,11,14,17‐EICOSAPENTAENOIC ACID AND OTHER POLYUNSATURATED FATTY ACIDS FROM LIPIDS AS A GRAZER DEFENSE REACTION IN EPILITHIC DIATOM BIOFILMS
Authors: Jüttner Friedrich
Published: March 2003

Acute grazer toxicity of freshwater diatom biofilms was determined using Thamnocephalus platyurus Packard, an anostracan grazer, as the bioassay organism. The diatoms exhibited toxicity when the cells of the biofilm were freeze–thawed before the assay. The toxicity could be extracted from the biofilms with methanol and acetone, and only minimal toxicity was left in the insoluble residue. Bioassay‐guided HPLC separation of the methanolic extract was performed to trace the most toxic components. Analysis by UV spectrometry, gas chromatography, and mass spectrometry showed that 5,8,11,14,17‐eicosapentaenoic acid was responsible for most grazer toxicity. The 24‐h LC50 of this polyunsaturated fatty acid was 34 μM in the Thamnocephalus platyurus bioassay. The concentrations of other free fatty acids were not high enough to contribute significantly to the toxicity. Procedures that affected the integrity of the cells (e.g. solvent extraction, freezing and thawing, osmotic stress by addition of 20% NaCl, or grinding the cells in a mortar) were taken as model reactions for grazing and had the common effect of resulting in a dramatic increase of free polyunsaturated and saturated fatty acids. Under these conditions, about 30% of the total fatty acids of the diatoms was transformed from the bound into the free form. The time necessary for liberation was very short. With the exception of 5,8,11,14,17‐eicosapentaenoic acid, which continued to be liberated, the hydrolysis of the other fatty acids was terminated less than 1 min after initiating the reaction. The classical extraction procedures using methanol and other solvents led to the appearance of a high percentage of free fatty acids in live cells. Treatment of biofilms with these solvents did not stop the hydrolysis of lipids initiated by the disintegration of the cells. However, boiling acetone completely suppressed the hydrolytic reactions, and free polyunsaturated fatty acids were not detected in live biofilm organisms, although nontoxic saturated fatty acids were present in moderate concentrations. These results were interpreted as an indication that the frequently reported existence of free polyunsaturated fatty acids in live biomass is an analytical artifact.
COMPOSITION AND SYNTHESIS OF THE PECTIN AND PROTEIN COMPONENTS OF THE CELL WALL OF CLOSTERIUM ACEROSUM (CHLOROPHYTA)
Authors: Baylson F. Ariella , Stevens Brian W. , Domozych David S.
Published: March 2003

Closterium acerosum Ehrenberg (Chlorophyta) possesses a trilayered cell wall consisting of an outer tri‐laminate stratum, a fibrous middle layer, and a thick inner fibrous layer. The outermost layer has a series of external parallel ridges and valleys. At the bases of the valleys are the wall pores, the site of mucilage release. Pure fractions of cell walls were isolated and inclusive pectin and wall protein fractions were extracted and characterized. Two pectin‐like fractions were isolated: a CDTA‐extracted polymer consisting of 60.1% galacturonic acid and a Na2CO3‐extracted fraction consisting of 39.9% galacturonic acid. Two major protein fractions, one with a molecular mass of 23.5 kDa and one with a molecular mass of 28.5 kDa, were isolated by preparative gel electrophoresis. The former was glycine‐rich, whereas the latter contained both significant amounts of glycine and hydroxyproline. Antibodies were raised to both the pectin fractions and the 23.5‐kDa wall protein fraction. Immunocytochemical labeling of whole cells and wall fragments using antibodies raised against CDTA and Na2CO3 extracts showed that these pectin‐like components were found throughout the wall strata and were more concentrated at the polar tips, the site of new wall synthesis in growing semicells. Immunogold labeling showed that their production was focused on the trans‐Golgi network of the Golgi apparatus. Immunolabeling with an antibody raised against the 23.5‐kDa glycine‐rich wall protein showed close association of the protein with the wall pores. Similarly, immunogold labeling revealed that the protein was processed throughout the entire Golgi body even when large mucilage‐containing vesicles were being processed. The roles of the secretory apparatus and putative spitzenkorper‐like regions of the cell are discussed.
GENETIC COMPARISONS OF FRESHLY ISOLATED VERSUS CULTURED SYMBIOTIC DINOFLAGELLATES: IMPLICATIONS FOR EXTRAPOLATING TO THE INTACT SYMBIOSIS
Authors: Santos Scott R. , Taylor Derek J. , Coffroth Mary Alice
Published: March 2003

Zooxanthellae, algal symbionts in divergent marine invertebrate hosts, are a genetically heterogeneous group. All species descriptions and most physiological and infectivity studies of zooxanthellae have been conducted using cultured material. However, few studies have attempted to quantify the representation of cultures isolated from cnidarians to the in hospite zooxanthella populations of the individual host or host species from which they were established. RFLPs of small subunit (18S) rDNA, internal transcribed spacer (ITS)‐rDNA sequence data, and microsatellite analyses were conducted to assess the relatedness between cultured zooxanthellae and the in hospite populations of the individual host or host species from which they were isolated. RFLP data demonstrated that cultures may represent either the numerically dominant symbiont or ones present in lower number. ITS‐rDNA sequences from zooxanthella cultures were disconcordant with ITS‐rDNA sequences identified from in hospite zooxanthellae of the same host species, and microsatellites present in in hospite zooxanthella populations were absent from the corresponding cultures. Finally, reexamination of the literature revealed examples of zooxanthella cultures being nonrepresentative of in hospite populations. These data suggest that, in most cases, cultures are a subset of the original in hospite population. Factors such as failing to homogenize bulk cultures before transfer, growth medium used, and the picking of single motile cells may contribute to many zooxanthella cultures being nonrepresentative.
SOLVING TAXONOMIC AND NOMENCLATURAL PROBLEMS IN PACIFIC GIGARTINACEAE (RHODOPHYTA) USING DNA FROM TYPE MATERIAL
Authors: Hughey Jeffery R. , Silva Paul C. , Hommersand Max H.
Published: March 2003

Molecular data obtained by a procedure for extracting PCR‐amplifiable nuclear and chloroplast DNA from old and formalin‐fixed red algal herbarium specimens were used to elucidate problems in the systematics of Pacific Gigartinaceae. Correspondence between nucleotide sequences of the internal transcribed spacer 1 region or the RUBISCO spacer from type specimens and modern collections supports the following conclusions. (1) The type of Fucus cordatus Turner, now Iridaea cordata (Turner) Bory, came from the southern hemisphere (probably from Isla de los Estados, Argentina) rather than from Banks Island, B.C., Canada. (2) The type of Iridaea heterocarpa P. et R. [Mazzaella heterocarpa (P. et R.) Fred.] represents the tetrasporangial phase of a species of Chondrus, possibly C. crispus Stackh. (3) The types of Iridaea lilacina P. et R., I. phyllocarpa P. et R., and Iridophycus furcatum S. et G. represent a single species from Alaska, Mazzaella phyllocarpa (P. et R.) Perest., currently but incorrectly called M. heterocarpa. (4) The type of Iridophycus oregonum Doty represents the tetrasporangial phase of the species from southern Alaska to southern California known incorrectly as M. heterocarpa. (5) Mazzaella splendens (S. et G.) Fred. is more closely related to M. linearis (S. et G.) Fred. than it is to M. flaccida (S. et G.) Fred. (6) Iridophycus coriaceum S. et G. is conspecific with M. splendens, whereas Rhodoglossum coriaceum E.Y. Dawson is an independent species: Mazzaella coriacea (E.Y. Dawson) Hughey. (7) Iridaea cornucopiae P. et R. is conspecific with Mazzaella laminarioides (Bory) Fred., and the type probably came from Chile rather than from the North Pacific. (8) Plants attributed to Iridaea cornucopiae in Pacific North America are referable to Mazzaella parksii (S. et G.) comb. nov. (9) Rhodoglossum parvum G. M. Smith et Hollenb. is an independent species: Mazzaella parva (G. M. Smith et Hollenb.) comb. nov. (10) Grateloupia squarrulosa S. et G., Grateloupia johnstonii S. et G., and Gigartina pectinata E.Y. Dawson represent a single species: Chondracanthus squarrulosus (S. et G.) comb. nov.
BLUE LIGHT AND UV‐A RADIATION CONTROL THE SYNTHESIS OF MYCOSPORINE‐LIKE AMINO ACIDS IN CHONDRUS CRISPUS (FLORIDEOPHYCEAE)
Authors: Franklin Linda A. , Kräbs Gudrun , Kuhlenkamp Ralph
Published: March 2003

The induction of UV‐absorbing compounds known as mycosporine‐like amino acids (MAAs) by red, green, blue, and white light (43% ambient radiation greater than 390 nm) was examined in sublittoral Chondrus crispus Stackh. Fresh collections or long‐term cultures of sublittoral thalli, collected from Helgoland, North Sea, Germany, and containing no measurable amounts of MAAs, were exposed to filtered natural radiation for up to 40 days. The MAA palythine (λmax 320 nm) was synthesized in thalli in blue light to the same extent observed in control samples in white light. In contrast, thalli in green or red light contained only trace amounts of MAAs. After the growth and synthesis period, the photosynthetic performance of thalli in each treatment, measured as pulse amplitude modulated chlorophyll fluorescence, was assessed after a defined UV dose in the laboratory. Thalli with MAAs were more resistant to UV than those without, and exposure to UV‐A+B was more damaging than UV‐A in that optimal (Fv/Fm) and effective (φII) quantum yields were lower and a greater proportion of the primary electron acceptor of PSII, Q, became reduced at saturating irradiance. However, blue light‐grown thalli were generally more sensitive than white light control samples to UV‐A despite having similar amounts of MAAs. The most sensitive thalli were those grown in red light, which had significantly greater reductions in Fv/Fm and φII and greater Q reduction. Growth under UV radiation alone had been shown previously to lead to the synthesis of the MAA shinorine (λmax 334 nm) rather than palythine. In further experiments, we found that preexposure to blue light followed by growth in natural UV‐A led to a 7‐fold increase in the synthesis of shinorine, compared with growth in UV‐A or UV‐A+B without blue light pretreatment. We hypothesize that there are two photoreceptors for MAA synthesis in C. crispus, one for blue light and one for UV‐A, which can act synergistically. This system would predispose C. crispus to efficiently synthesize UV protective compounds when radiation levels are rising, for example, on a seasonal basis. However, because the UV‐B increase associated with artificial ozone reduction will not be accompanied by an increase in blue light, this triggering mechanism will have little additional adaptive value in the face of global change unless a global UV‐B increase positively affects water column clarity.
TAXONOMY AND MOLECULAR PHYLOGENY OF THE RED ALGAL GENUSLENORMANDIA(RHODOMELACEAE, CERAMIALES)1
Authors: Phillips Louise E.
Published: March 2003

The genusLenormandiaSonder is currently composed of nine species from Australia and New Zealand. Some of these are well known, but others are rare and ill defined. Material of all nine species has been examined and found to fall into three discrete morphological groups forming highly supported clades on analysis of 18S rDNA sequences. The first group contains four Australian‐endemic species and includes the type speciesL. spectabilisSonder. Plants have a cleft apex that is not inrolled, a distinctive rhombic surface areolation pattern caused by a one‐ to two‐layered medulla of interlocking cells, lack pseudopericentral cells, and produce their reproductive structures on the blade surfaces. The type species of the genusLenormandiopsis,L. latifolia(HarveyetGreville) Papenfuss, was found to belong to this group and is thus returned toLenormandiawhere it was originally placed. Species falling into the other two groups are removed to new genera that are being described separately. One extremely rare species ofLenormandiafrom southwestern Australia is transferred to the delesseriacean genusPhitymophora.
IDENTIFICATION OF BACTERIA ASSOCIATED WITH DINOFLAGELLATES (DINOPHYCEAE) ALEXANDRIUM SPP. USING TYRAMIDE SIGNAL AMPLIFICATION–FLUORESCENT IN SITU HYBRIDIZATION AND CONFOCAL MICROSCOPY1
Authors: Biegala Isabelle C. , Kennaway Gabrielle , Alverca Elsa , Lennon Jean‐François , Vaulot Daniel , Simon Nathalie
Published: March 2003

In the marine environment, phytoplankton and bacterioplankton can be physically associated. Such association has recently been hypothesized to be involved in the toxicity of the dinoflagellate genus Alexandrium. However, the methods, which have been used so far to identify, localize, and quantify bacteria associated with phytoplankton, are either destructive, time consuming, or lack precision. In the present study we combined tyramide signal amplification–fluorescent in situ hybridization (TSA‐FISH) with confocal microscopy to determine the physical association of dinoflagellate cells with bacteria. Dinoflagellate attached microflora was successfully identified with TSA‐FISH, whereas FISH using monolabeled probes failed to detect bacteria, because of the dinoflagellate autofluorescence. Bacteria attached to entire dinoflagellates were further localized and distinguished from those attached to empty theca, by using calcofluor and DAPI, two fluorochromes that stain dinoflagellate theca and DNA, respectively. The contribution of specific bacterial taxa of attached microflora was assessed by double hybridization. Endocytoplasmic and endonuclear bacteria were successfully identified in the nonthecate dinoflagellate Gyrodinium instriatum. In contrast, intracellular bacteria were not observed in either toxic or nontoxic strains of Alexandrium spp. Finally, the method was successfully tested on natural phytoplankton assemblages, suggesting that this combination of techniques could prove a useful tool for the simultaneous identification, localization, and quantification of bacteria physically associated with dinoflagellates and more generally with phytoplankton.
CONFIRMATION OF DOMOIC ACID PRODUCTION BY PSEUDO‐NITZSCHIA AUSTRALIS (BACILLARIOPHYCEAE) ISOLATED FROM IRISH WATERS1
Authors: Cusack Caroline K. , Bates Stephen S. , Quilliam Michael A. , Patching John W. , Raine Robin
Published: March 2003

A nonaxenic isolate of the potentially toxic diatom Pseudo‐nitzschia australis (Frenguelli) from Irish waters was tested in two separate batch culture experiments. When grown under a low irradiance (∼12 μmol photons·m−2·s−1; 16:8‐h light:dark cycle) for up to 40 days, the culture produced only trace amounts of the neurotoxin domoic acid (DA) during late stationary phase. Growth at a higher irradiance (∼115 μmol photons·m−2·s−1; 12:12‐h light:dark cycle) resulted in DA production starting during late exponential phase and reaching a maximum concentration of 26 pg DA·cell−1 during late stationary phase. Liquid chromatography coupled to mass spectrometry was used to confirm the identity of DA in the culture. Irradiance and photoperiod could be important factors that contribute directly or indirectly to the control of DA production in P. australis. This is the first record of a DA‐producing diatom in Irish waters, and results indicate P. australis may have been the source of DA that has recently contaminated shellfisheries in this area.
A PCR‐BASED TEST TO ASSESS THE POTENTIAL FOR MICROCYSTIN OCCURRENCE IN CHANNEL CATFISH PRODUCTION PONDS1,2
Authors: Nonneman Dan , Zimba Paul V.
Published: March 2003

Microcystis aeruginosa is a common form of cyanobacteria (blue‐green algae) capable of forming toxic heptapeptides (microcystins) that can cause illness or death. Occasionally, blooms of cyanobacteria have caused toxic fish‐kills in catfish production ponds. We have developed a PCR test that will detect the presence of microcystin‐producing cyanobacteria. Microcystin producers are detected by the presence of the microcystin peptide synthetase B gene (an obligate enzyme in the microcystin pathway), which appears to be present only in toxin‐producing cyanobacteria. These PCR amplifications can be performed in multiplex using purified DNA from pond waters or by two‐stage amplification from native water samples. A synoptic survey of 476 channel catfish production ponds from four states in the southeastern United States revealed that 31% of the ponds have the genetic potential to produce microcystins by toxic algae.
PRODUCTION OF PARALYTIC SHELLFISH TOXINS BY APHANIZOMENON SP. LMECYA 31 (CYANOBACTERIA)1
Authors: Dias Elsa , Pereira Paulo , Franca Susana
Published: March 2003

We examined intracellular and extracellular paralytic shellfish toxins (PST) in a strain of Aphanizomenon sp. (LMECYA31) isolated from a Portuguese freshwater reservoir throughout the growth cycle and under different conditions affected by temperature and nitrate and phosphate availability. PST concentrations and compositions were greatly influenced by cell density, growth stage, and temperature and nutrients conditions. On a per‐cell basis results showed (1) the enhancement of PST cell quota after the end of exponential growth phase in nutrient replete batch cultures, (2) the absence of a PST increment at late growth stages under phosphate limitation, (3) a rise in PST maximum cell quota under nitrate depletion, and (4) the enhancement of toxin production at higher temperatures. The relative proportion of the four toxins detected, neoSTX, dcSTX, STX and GTX5, also changed within and between culture settings. While growing under phosphate rich media cells produced mainly GTX5 and neoSTX, whereas under phosphate limitation the proportion of STX and dcSTX increased substantially with culture age. Large amounts of extracellular toxins were found in the culture medium, increasing during culture time. Extracellular toxin composition in each culture was fairly constant and always similar to the intracellular composition found at late stages of growth. This further supported other research that indicates that PSTs are released to the water through cell lysis, and a significant concentration of PST may be expected to remain in the water upon the collapse of a toxic bloom or after cells removal by water treatment.