bluuebunny/crossref_metadata_2025 huggingface dataset:
ATLANTIC KELP SPECIES LAMINARIA LONGICRURIS AND L. SACCHARINA (LAMINARIALES) ARE CONSPECIFIC
Authors: Cho G.Y. , Yoon H.S. , Boo S. M. , Yarish C.
Published: March 2003

The identification of two Atlantic kelp species, Laminaria longicruris and L. saccharina, has been controversial. In order to know if these two species are conspecific, plastid‐encoded RuBisCo spacer and nuclear rDNA ITS sequences were analyzed from twelve individuals of L. longicruris, five of L. saccharina, from Connecticut and Nova Scotia. Four individuals of L. digitata from the above coasts were also analyzed as reference in this study. All RuBisCo spacer sequences from L. longicruris and L. saccharina were exactly identical except for one individual with three different nucleotides. Zero to five different nucleotides of ITS sequences, inculding four polymorphic sites, were found in two species. However, their RuBisCo spacer and ITS sequences are quite different from those of L. digitata. These results strongly suggest that L. saccharina (L.) Lamour. 1813 is conspecific with L. longicruris De La Pylaie 1824 and the different local populations, despite various morphotypes, may be genetically very similar.
ALGAL COMMUNITY STRUCTURE OF THE EAST AND WEST FLOWER GARDEN BANKS, NORTHWESTERN GULF OF MEXICO
Authors: Albert E. M. , Lehman R. L.
Published: March 2003

The algal communities of the Flower Garden Banks National Marine Sanctuary have not been comprehensively evaluated and only a few dominant macroalgal species have been reported. This study utilizes both destructive and non‐destructive sampling techniques to characterize and taxonomically identify the ‘algal mat’ community structure. The East and West Flower Garden Banks are located on the outer continental shelf approximately 200 km off the Texas‐Louisiana coastline. The average depth of both banks is 100 m with the crest approximately 20 m from the surface. Harvest and photogrammetric samples were collected during two extended cruises to the Flower Garden Banks in October 1998 and March 1999. Forty, 0.25‐m2 quadrats of standing stock material were randomly collected along with one hundred sixty‐one 0.25 m2 photo‐quadrats from an average depth of 27 m. Photo‐transparencies were projected to an actual size grid with 25 random points. Four thousand twenty‐five transparency points were evaluated and used to calculate percent composition of algal cover. Harvest samples were used to characterize the “algal mat” composition, species richness, abundance, and biomass. Forty‐two species were identified from the samples representing 14 Orders. The “red algal mat” was the dominant algal coverage comprising 38.4% of all photogrammetric samples. This mat was primarily composed of members from the Order Ceramiales. Centroceras, Ceramium, and Polysiphonia comprised 33.4% of the mat, Anotrichium and Hypoglossum, 22.4%.
PRELIMINARY ANALYSIS OF QUANTITATIVE GENETICS AND PHENOTYPIC PLASTICITY IN AULACOSEIRA SUBARCTICA (BACILLAR‐IOPHYTA)
Authors: Edgar S. M. , Theriot E.C.
Published: March 2003

Several clones of Aulacoseira subarctica were isolated from Yellowstone, Lewis, and East Rosebud Lakes (Montana, Wyoming). Two to four clones from each lake were grown in batch cultures under three light intensities, 2, 11.4 and 115 μE m−2 s−1. Clones were conditioned to their light environment for a three‐week period. Inoculants from the conditioned clones taken during log phase of growth, were grown until in log phase, then samples were collected. Five randomly chosen valves for 2 replicates of each clone were examined using a scanning electron microscope and captured on film at a magnification of 20,000x. Each image was digitized and quantitative morphometric characters were measured. A preliminary quantitative genetic analysis was performed on selected characters within each light environment. Plasticity of characters within clones across the three light regimes were also examined. The amount of variability found within characters in A. subarctica will be discussed in terms of environmental, genetic, and microenvironmental sources.
CO‐OCCURRENCE OF CARRAGEENANS AND AGAROIDS IN GYMNOGONGRUS TORULOSUS (GIGARTINALES, PHYLLOPHORACEAE) FROM ARGENTINA
Authors: Estevez J. M. , Ciancia M , Cerezo A.S.
Published: March 2003

The red seaweeds, Gigartina skottbetgii and Sarcothalia crispata, have commercial value as raw material for the industrial production of phycocolloids (carrageenans) in Argentina. The third alga with potencial possibilities for the carrageenan production is Gymnogongrus torulosus. Herein, we report the study of the polysaccharide system present in Gymnogongrus torulosus, which contribute to the estimation of the importance of this algae in the seaweed industry. Analysis of the hot water‐soluble extract (C1), by FT‐IR, methylation and 13C NMR, showed mainly the presence of iota/kappa carrageenan hybrid (molar ratio ∼ 2:1). The soluble fractions obtained after KCl fractionation (F3, 16.1 % of C1) and soluble after alkaline treatment and KCl fractionation (F3T3, 34.6% of F3T) gave negative optical rotations (−15.5 and −55.4, respectively), considerably lower than those reported for kappa/iota carrageenans (from 56.1 to 66.5). These fractions (F3 and F3T3) have significant quantities of L‐galactose (11.1% and 29.8%) and L‐3,6‐anhydrogalactose (19.2% and 4.3%). The direct relationship between the optical rotation and the percentage of L‐galactose indicated that its structural influence is similar in all the fractions. The results suggest that Gymnogongrus torulosus biosynthesizes a polysaccharide system with co‐occurrence of carrageenans and agaroids in the same thallus.
PHOTOSYNTHESIS‐IRRADIANCE PATTERNS IN BENTHIC MICROALGAE: VARIATIONS AS A FUNCTION OF ASSEMBLAGE THICKNESS AND COMMUNITY STRUCTURE
Authors: Dodds Walter K. , Biggs Barry J. F. , Lowe Rex L.
Published: March 2003

Photosynthesis‐irradiance (P‐I) characteristics of periphyton (microphytobenthos) have been considered primarily for entire assemblages. How P‐I responses vary with mat thickness and with community composition has not been considered in detail. We used a combined approach of modeling, microscale determinations of photosynthetic rate and light attenuation, and whole‐assemblage O2 flux measurements to explore P‐I relationships. The modeling approach suggested that the onset of photosynthetic saturation and photoinhibition will occur at higher irradiance and that whole‐mat photoinhibition (decreased photosynthesis at very high irradiance), biomass‐specific maximum photosynthetic rate, and initial slope of the P‐I function (α) should decrease as assemblage thickness increases or light attenuation increases. Spherical light microsensor profiles for a variety of stream algae indicated a strongly compressed photic zone with attenuation coefficients of 70–1791 m−1 for scalar photosynthetic photon fluence density. The O2 microelectrode measurements showed little if any photoinhibition at 2 and 4 mm depths in one filamentous green algal (Ulothrix) assemblage, with a relatively low attenuation coefficient, and no photoinhibition in a second Ulothrix community. An assemblage dominated by a unicellular cyanobacterium exhibited little photoinhibition at 2 and 4 mm, and a dense cyanobacterial (Phormidium)/xanthophyte (Vaucheria) community exhibited no photoinhibition at all. The microelectrode data revealed increases in α over several millimeters of depth (photoacclimation). These data supported the model predictions with regard to the effects of mat optical thickness on whole‐assemblage values for α and photoinhibition. Whole‐community O2 flux data from 15 intact assemblages revealed positive relationships between chlorophyll a density and maximum photosynthetic rate or α expressed per unit area; the relationships with chlorophyll a were negative when photosynthetic rates were expressed per unit chlorophyll a. None of the whole assemblages exhibited photoinhibition. Thus, the data from the whole communities were consistent with model predictions.
COMMERCIAL DEVELOPMENTS IN MICROALGAL BIOTECHNOLOGY
Authors: Apt Kirk E. , Behrens Paul W.
Published: March 2003

A number of important advances have occurred in microalgal biotechnology in recent years that are slowly moving the field into new areas. New products are being developed for use in the mass commercial markets as opposed to the “health food” markets. These include algal‐derived long‐chained polyunsaturated fatty acids, mainly docosahexaenoic acid, for use as supplements in human nutrition and animals. Large‐scale production of algal fatty acids is possible through the use of heterotrophic algae and the adaptation of classical fermentation systems providing consistent biomass under highly controlled conditions that result in a very high quality product. New products have also been developed for use in the development of pharmaceutical and research products. These include stable‐isotope biochemicals produced by algae in closed‐system photobioreactors and extremely bright fluorescent pigments. Cryopreservation has also had a tremendous impact on the ability of strains to be maintained for long periods of time at low cost and maintenance while preserving genetic stability.
LOW‐TEMPERATURE‐INDUCED SYNTHESIS OF α‐CAROTENE IN THE MICROALGA DUNALIELLA SALINA (CHLOROPHYTA)
Authors: Orset Sandra , Young Andrew J.
Published: March 2003

The microalga Dunaliella salina (Teo.) is well known as an accumulator of β‐carotene (β,β‐carotene) when subjected to growth‐limiting conditions (e.g. exposure to high irradiances). In addition, the carotenoid α‐carotene (β,ε‐carotene) may also be synthesized and subsequently accumulated by this alga under specific growth conditions. The main factor in stimulating the synthesis of this carotene was determined to be exposure to lower than optimum temperatures for algal growth. A 7.5‐fold increase in the levels of α‐carotene was observed when the temperature was decreased from 34 to 17° C, whilst levels of β‐carotene were unaltered. The accumulation of α‐carotene was unaffected by irradiance, although its isomeric composition was greatly altered by light levels. The proportion of 9‐cisα‐carotene increased from 15% to 45% of total α‐carotene when the irradiance was decreased from 260 to 50 μmol·m−2·s−1. Exposure to higher irradiances had little influence on the isomeric composition of this carotenoid. A reduction in growth temperature did not influence the isomeric composition of α‐carotene. Nutrient status (nitrogen and phosphate) had no effect on either the content or isomeric composition of α‐carotene accumulated by D. salina.
CHARACTERIZATION OF A cDNA ENCODING GLUTAMINE SYNTHETASE FROM THE MARINE DIATOM SKELETONEMA COSTATUM (BACILLARIOPHYCEAE)
Authors: Robertson Deborah L. , Smith G. Jason , Alberte Randall S.
Published: March 2003

A cDNA‐encoding glutamine synthetase (GS) was isolated from the marine diatom Skeletonema costatum (Greville) Cleve by PCR amplification. Nucleic acid and deduced amino acid sequences of the diatom GS were greater than 50% identical to GS from green algae and vascular plants, and phylogenetic analysis established the diatom GS as a member of the GSII gene family. The presence of an N‐terminus signal sequence, identified on the basis of sequence similarity with other chloroplast‐localized proteins from diatoms, suggests that the encoded GS isoenzyme is localized to the chloroplast. The GS mRNA was present in log‐phase cells grown with either nitrate or ammonium as the sole added nitrogen source. Results from Southern blot analysis of genomic DNA suggested that the cDNA isolated in this study was either a member of a small, highly conserved gene family or that there was allelic variation within the region examined. Phylogenetic analyses further indicated that genes encoding GS from the diatom and two species of green algae diverged prior to the gene duplication, to the isoenzymes in vascular plants, supporting the hypothesis that GS isoenzymes in diatoms, green algae, and vascular plants arose through independent evolutionary events.
GEOGRAPHIC VARIATION IN THERMAL TRAITS IN DIGENEA SIMPLEX AND CHAMPIA PARVULA (RHODOPHYTA) IN RELATION TO PRESENT AND GLACIAL TEMPERATURE REGIMES
Authors: Orfanidis Sotiris , Breeman Anneke M.
Published: March 2003

Geographic variation in temperature responses (survival and growth) was investigated in two red algae: Digenea simplex (Wulfen) C. Agardh and Champia parvula (C. Agardh) Harvey. D. simplex has a tropical to warm temperate distribution; C. parvula extends from the tropics into the cold temperate zone. Ecoclinal variation was found in both species but was much stronger in C. parvula than in D. simplex. The former species showed variation in upper and lower tolerance limits as well as in the upper and lower limits for growth. The latter species showed variation mainly in its lower tolerance limit. Ecoclinal variation was related to the amount of present and glacial selection pressure along the climate gradient. In both species, isolates from the colder localities had insufficient cold tolerance to have survived low glacial winter temperatures, so these locations must have been colonized after the end of the glaciation. Eastern Mediterranean and Atlantic populations were probably isolated during the glaciation by a thermal barrier at the entrance of the Mediterranean. In C. parvula, evidence existed for a trade‐off between the performance at high and at low temperatures, which would enhance selection pressure in opposite directions at either end of the climatic range. No evidence for such a trade‐off was found in D. simplex.
OCCURRENCE OF CODIUM FRAGILE SUBSP. TOMENTOSOIDES (CHLOROPHYTA: BRYOPSIDALES) IN MARINE EMBAYMENTS OF SOUTHEASTERN AUSTRALIA
Authors: Campbell Stuart J.
Published: March 2003

Codium fragile (Sur.) Hariot subsp. tomentosoides (van Goor) Silva, a widespread weedy species, is reported from Australia for the first time. Specimens were initially found in June 1996 in Corner Inlet, Victoria, where the species fouled fishing nets. This invasive chlorophycean alga was subsequently found in large numbers on 30 January 1997 in Port Phillip Bay and on 9 March 1998 in Western Port, Victoria. Presumably the species is native to Japan. The alga formed dense stands on rocky substrata in intertidal or in subtidal regions. In Port Phillip Bay, the species was also found attached to the common blue mussel Mytilus edulis planulatus Lamarck, and in Western Port it was found attached to the mud oyster Ostrea angasi Sowerby. Results of this study suggest that recruitment of juvenile germlings and growth of C. fragile subsp. tomentosoides differs between populations in Port Phillip Bay and those in Western Port.
STUDIES OF POLYSACCHARIDES FROM THREE EDIBLE SPECIES OF NOSTOC (CYANOBACTERIA) WITH DIFFERENT COLONY MORPHOLOGIES: STRUCTURAL CHARACTERIZATION AND EFFECT ON THE COMPLEMENT SYSTEM OF POLYSACCHARIDES FROM NOSTOC COMMUNE
Authors: Brüll Lars P. , Huang Zebo , Thomas‐Oates Jane E. , Paulsen Berit Smestad , Cohen Ellen Hanne , Michaelsen Terje E.
Published: March 2003

The cyanobacterium Nostoc commune Vaucher produces quite complex extracellular polysaccharides. The cyanobacterium is nitrogen fixing, and on growing the cyanobacterium in media with and without nitrogen, different types of extracellular polysaccharides were obtained. These were also different from the polysaccharides present in N. commune collected in the field. High pH anion exchange chromatography (HPAEC) of weak acid hydrolysates of the culture‐grown material demonstrated that, in this case, HPAEC was useful for comparison of the different polymers. The main differences between the polymers from the field group and the culture‐grown samples were the presence of substantial amounts of arabinose, 2‐O‐methylglucose, and glucuronic acid in the latter. Methylation studies also revealed a difference in the branching points on the glucose units between the field and cultured samples, being 1,4,6 for the first and 1,3,6 for the latter. The field acidic fraction gave, on weak acid hydrolysis and separation on BioGel P2 and HPAEC, 12 oligosaccharide fractions that were isolated and studied by different mass spectroscopy techniques. The structures of the oligosaccharides were determined, and two different series that can originate from two repeating pentamers were identified: GlcA1‐4/6GlcM1‐4Gal1‐4Glc1‐4Xyl and GlcA1‐4/6Glc1‐4Gal1‐4Glc1‐4Xyl. The difference between these oligosaccharides lies in the methyl substituent on carbon 2 of the glucose unit next to the nonreducing glucuronic acid unit. The polysaccharides from field material were shown to have a strong effect on the complement system.
Effect of temperature on photosynthesis‐light response and growth of four phytoplankton species isolated from a tidal freshwater river
Authors: Coles James F. , Jones R. Christian
Published: March 2003

Three cyanobacteria (Microcystis aeruginosaKütz. emend. Elenkin,Merismopedia tenuissimaLemmermann, andOscillatoriasp.) and one diatom (Aulacoseira granulatavar.angustissimaO. Mull. emend. Simonsen) were isolated from the tidal freshwater Potomac River and maintained at 23° C and 40 μmol photons·m−2·s−1on a 16:8 L:D cycle in unialgal culture. Photosynthetic parameters were determined in nutrient‐replete cultures growing exponentially at 15, 20, 25, and 30° C by incubation with14C at six light levels.P  Bmaxwas strongly correlated with temperature over the entire range for the cyanobacteria and from 15 to 25° C forAulacoseira, withQ10ranging from 1.79 to 2.67. The α values demonstrated a less consistent temperature pattern. Photosynthetic parameters indicated an advantage for cyanobacteria at warmer temperatures and in light‐limited water columns.P  BmaxandIkvalues were generally lower than comparable literature and field values, whereas α was generally higher, consistent with a somewhat shade acclimated status of our cultures. Specific growth rate (μ), as measured by chlorophyll change, was strongly influenced by temperature in all species.Oscillatoriahad the highest μ at all temperatures, joined at lower temperatures byAulacoseiraand at higher temperatures byMicrocystis.Values of μ forAulacoseirawere near the low end of the literature range for diatoms consistent with the light‐limited status of the cultures. The cyanobacteria exhibited growth rates similar to those reported in other studies.Q10for growth ranged from 1.71 forAulacoseirato 4.16 forMicrocystis.Growth rate was highly correlated withP  Bmaxfor each species and the regression slope coefficients were very similar for three of the species.
Scrippsiella trochoideaandscrippsiella regalis, nov. comb. (peridiniales, dinophyceae): a comparison
Authors: Janofske Dorothea
Published: March 2003

Culture experiments on dinoflagellates from the Atlantic Ocean revealedScrippsiella regalis(Gaarder) Janofske, nov. comb., a calciodinelloid species with a spherical spiny calcareous cyst. This calcareous cyst was collected previously from plankton and sediment samples, where it was described as the coccolithophoridDiscosphaera regalisGaarder or was often mistaken for the cyst ofScrippsiella trochoidea(von Stein) Loeblich III. The morphological features of both the cellulosic theca and the calcareous cyst ofS. trochoideaandS. regaliswere compared with respect to their systematic position and the emendation of taxa. Both species were found to have different distribution patterns.Scrippsiella trochoideais known only from the neritic environment, whereasS. regalishas been found mostly in oceanic samples. The preservation of these spiny calcareous dinocysts in the (fossil) sediment was dependent on the ultrastructure of the calcareous layer of the cyst wall.
On detection of pseudo‐nitzschia (bacillariophyceae) species using whole cell hybridization: sample fixation and stability
Authors: Miller Peter E. , Scholin Christopher A.
Published: March 2003

Some species within the genus Pseudo‐nitzschia H. Peragallo are associated with production of domoic acid, the agent responsible for amnesic shellfish poisoning (ASP). Identification and enumeration of particular Pseudo‐nitzschia in natural populations is often difficult and time consuming because of the need for detailed morphological observations, which often require scanning or transmission electron microscopy. In earlier publications we described the development of large subunit ribosomal RNA (LSU rRNA)‐targeted fluorescent DNA probes for discriminating among a variety of Pseudo‐nitzschia species collected from Monterey Bay, California. Probes are applied using whole cell hybridization and a custom filtration manifold, enabling rapid identification and quantification of target species in cultured as well as field samples. In this work we compared a variety of preservation techniques and assessed the stability of stored samples with respect to their reactivity towards the probes. Of the preservatives tested, a saline ethanol‐based treatment gave the best results in terms of probes yielding a bright and uniform cell label. Culture samples treated with this fixative continued to react well with the probes for at least 6 weeks post‐fixation whether stored in the preservative or dried post‐preservation, with samples being kept at either room temperature or −20° C. Likewise, field samples containing a variety of diatoms and dinoflagellate species stored in the saline ethanol solution at room temperature were also stable for at least 4–6 weeks, reacting brilliantly towards a positive control probe. After prolonged storage, however, cell reactivity towards the probes diminished dramatically. Post‐hybridization, samples stored at 4° C were found to retain their fluorescence for at least 1 week. These results indicate a wider window of opportunity for Pseudo‐nitzschia analysis using whole cell hybridization than previously reported. Sample collection, preservation, and probing protocols optimized for Pseudo‐nitzschia are also applicable to a wide range of phytoplankton species. The time required to execute the whole cell hybridization protocol was reduced by premixing probe with hybridization buffer. The premixed probe solutions as well as fixative and wash solutions are all stable at room temperature for at least 6 weeks. Application of two different species‐specific probes, each labeled with a different fluorochrome, allowed detection of two species on a single filter. The latter could be adopted in the future to increase the rate of sample processing and decrease the cost of sample analysis.
srDna‐based taxonomic affinities of algal symbionts from a planktonic foraminifer and a solitary radiolarian
Authors: Gast Rebecca J. , McDonnell Tracey A. , Caron David A.
Published: March 2003

Planktonic sarcodines (acantharia, radiolaria, and planktonic foraminifera) are oceanic amoeboid protozoa that often harbor a variety of microalgae as intracellular symbionts. The identity and function of these endosymbiotic algae have intrigued and perplexed biologists for more than a century. The most conspicuous and well‐studied symbiotic algae of planktonic foraminifera and radiolaria are dinoflagellates, but a variety of nondinoflagellate taxa have also been reported. Ultrastructural features have been used to characterize some of these nondinoflagellate algae, but rarely has this led to clear taxonomic affiliations. We analyzed the nuclear small subunit ribosomal DNA (srDNA) isolated from the symbionts of the spinose planktonic foraminiferan Globigerinella siphonifera d'Orbigny (=Globigerinella aequilateralis Brady) and a solitary radiolarian (Spongodrymus sp. Haeckel) in order to determine the identity of these symbionts. The small coccoid algae isolated from G. siphonifera correspond to the Type I symbionts described by Faber et al. (1988). Phylogenetic analysis of the srDNA sequences places these symbionts within the prymnesiophyte (haptophyte) lineage, closer to Prymnesium Conrad than to Phaeocystis Lagerheim. To our knowledge, this is the first confirmed case of a symbiotic prymnesiophyte. In addition, we were able to examine the level of sequence heterogeneity between symbionts isolated from different individuals of a single host species. The three isolates in this study had srDNA sequences that were almost identical, indicating that the three were all of the same species. Very green symbiotic algae were isolated from three solitary radiolaria identified as species of Spongodrymus. The symbiont srDNA sequences from the three individual hosts were identical to each other, again implicating a single species of algae in that symbiotic association. These symbionts are prasinophytes most closely related to the clade containing Tetaselmis convolutae Norris, Hori et Chihara. Tetraselmis convolutae is the algal symbiont of the marine flatworm, Convolutae roscoffensis Graff.
MONOPHYLY OF THE GENUS CLOSTERIUM AND THE ORDER DESMIDIALES (CHAROPHYCEAE, CHLOROPHYTA) INFERRED FROM NUCLEAR SMALL SUBUNIT rDNA DATA
Authors: Denboh Takashi , Hendrayanti Dian , Ichimura Terunobu
Published: March 2003

We newly sequenced the nuclear‐encoded small subunit (SSU) rDNA coding region for 21 taxa of the genus Closterium. The new sequences were integrated into an alignment with 13 known sequences of conjugating green algae representing six traditional families (i.e. Zygnemataceae, Mesotaeniaceae, Gonatozygaceae, Peniaceae, Closteriaceae, and Desmidiaceae) and five known charophycean sequences as outgroups. Both maximum likelihood and maximum parsimony analyses supported with high bootstrap values one large clade containing all placoderm desmids (Desmidiales). All the Closterium taxa formed one clade with 100% bootstrap support, indicating their monophyly, but not paraphyly, as suggested earlier. As to the taxa within the genus Closterium, we found two clades of morphologically closely related taxa in both maximum likelihood and maximum parsimony trees. They corresponded to the C. calosporum species complex and the C. moniliferum‐ehrenbergii species complex. It is of particular interest that the homothallic entity of C. moniliferum v. moniliferum was distinguished from and ancestral to all other entities of the C. moniliferum‐ehrenbergii species complex. Superimposing all 50 charophycean sequences on the higher order SSU rRNA structure model of Closterium, we investigated degrees of nucleotide conservation at a given position in the nucleotide sequence. A characteristic “signature” structure to the genus Closterium was found as an additional helix at the tip of V1 region. In addition, eight base deletions at the tip of helix 10 were found to be characteristic of the C. calosporum species complex, C. gracile, C. incurvum, C. pleurodermatum, and C. pusillum v. maius. These taxa formed one clade with an 82% bootstrap value in maximum parsimony analysis.
ULTRASTRUCTURE OF THE BASAL BODY COMPLEX AND PUTATIVE VESTIGIAL FEEDING APPARATUS IN PHACUS PLEURONECTES (EUGLENOPHYCEAE)
Authors: Shin Woongghi , Boo Sung Min , Triemer Richard E.
Published: March 2003

Phacus pleuronectes (O. F. Müller) Dujardin is a phototrophic euglenoid with small discoid chloroplasts, a flat rigid body, and longitudinally arranged pellicular strips. The flagellar apparatus consisted of two basal bodies and three flagellar roots typical of many phototrophic euglenoids but also had a large striated fiber that connected the two basal bodies and associated with the ventral root. The three roots, in combination with the dorsal microtubular band, extended anteriorly and formed the major cytoskeletal elements supporting the reservoir membrane and ultimately the pellicle. A cytoplasmic pocket arose in the reservoir/canal transition region. It was supported by the ventral root and a C‐shaped band of electron‐opaque material that lined the cytoplasmic side of the pocket. A large striated fiber extended from this C‐shaped band toward the reservoir membrane. The striated fibers in the basal apparatus and associated with the microtubule‐reinforced pocket in P. pleuronectes appear to be similar to those of the phagotrophic euglenoids.
EVIDENCE FOR SEXUAL REPRODUCTION IN THE MARINE DINOFLAGELLATES, PYROCYSTIS NOCTILUCA AND PYROCYSTIS LUNULA (DINOPHYTA)
Authors: Seo Kyung Suk , Fritz Lawrence
Published: March 2003

Evidence for sexual reproduction was observed in two oceanic dinoflagellate species, Pyrocystis noctiluca Murray ex Haeckel and Pyrocystis lunula (Schütt) Schütt. Observations suggest that cells underwent fertilization as opposed to cell division because of the following: first, fusing cells had a conspicuous pore (fusion pore) connecting the two gametes; dividing cells lacked this feature. In culture, about 0.1% of P. noctiluca cells had a fusion pore, which serves as a possible site for gamete recognition on the cell wall. Second, we document a temporal progression of plasmogamy and karyogamy. Fusion events in both species were observed at the beginning of the day, whereas division stages were most apparent at the end of the day.
CHARACTERIZATION OF TWO UNIQUE CAROTENOID FATTY ACID ESTERS FROM PTEROSPERMA CRISTATUM (PRASINOPHYCEAE, CHLOROPHYTA)1
Authors: Yoshii Yukie , Takaichi Shinichi , Maoka Takashi , Hanada Satoshi , Inouye Isao
Published: March 2003

Carotenoid composition and spectroscopic characteristics were analyzed for Pterosperma cristatum Schiller, one of the most primitive known members of green algae. This alga contained a substantial amount of carotenoid esters, siphonaxanthin C14:1 trans‐Δ2 ester and 6′‐OH siphonaxanthin C14:1 trans‐Δ2 ester, but lacked lutein. This is the first report of carotenoid C14:1 trans‐Δ2 esters from phototrophic organisms. In vivo absorption spectra and excitation spectra of the cells revealed that these carotenoids absorbed blue‐green light and could transfer energy to chl a. These carotenoids were concluded to function as antenna pigments in P. cristatum.
Effects of Sampling Scale and Analysis Method on Perceptions of Phytoplankton Species Associations
Authors: Davis B. E. , Interlandi S. J. , Kilham S. S. , Theriot E. C.
Published: March 2003

Phytoplankton associations generally are identified by nonrandom co‐occurrence of phytoplankton species, and are considered to be a result of similar species response to properties of the environment. Because an association is characterized by co‐occurrence of species across samples, or synchrony of the abundance of species over time, we proposed that the perception of phytoplankton association is subject to spatial and temporal sampling scale and analysis method. We investigated this using an intensive phytoplankton dataset from three lakes of the Greater Yellowstone Ecosystem, with particular concentration on Asterionella formosa (AF) and Aulacoseira subarctica (AS). We compared numerical analyses, including Fager analysis of recurrent groups, rank correlation, and other measures of synchrony, for differences in assessment of co‐occurrence. The analyses were conducted on the entire dataset, and then the dataset was reduced to assess the effect of different spatial or temporal sampling regimes on apparent association. While the two diatom species significantly co‐occurred across samples, assessment of synchrony was affected by analysis method and sampling regime. AF and AS abundance were positively correlated across lakes and within each lake, but peaks in abundance of the two species did not significantly coincide over time. In addition, species abundance were negatively correlated across depths, and we argue that this is significant to the autecology of each species. These results indicate that the perception of phytoplankton association may simply be an artifact of the limits of our understanding of the distribution and physiology of the organisms.
A Guide to the Seaweeds of Florida
Authors: Dawes C. J. , Mathieson A. C.
Published: March 2003

A review of Florida seaweeds indicates a highly diverse flora within a large coastal zone (over 700 km) spanning more than 7° of latitude, containing tropical, subtropical, and temperate communities. Surprisingly, there have been relatively few detailed floristic studies of Florida seaweeds, except for the Florida Keys and on the east coast. The patterns are a reflection of the early predominance of winter visitors and lack of resident phycologists. The seaweeds of the west coast of Florida were virtually ignored until the 1950s. We estimate that the state's seaweed flora consists of at least 670 taxa including 219 green, 97 brown, 349 red algae, and at least 3 species of Vaucheria. Such a compilation is significantly higher than the numbers of taxa recorded for Florida by Taylor (1960), as well as those for North Carolina (i.e. Schneider & Searles, 1991), and Caribbean reefs (Littler & Littler, 2000). The majority of Florida seaweeds have tropical/Caribbean affinities, although a significant temperate component also occurs, presumably reflecting the influence of the northern floras of the Gulf of Mexico and south‐eastern coast of the US. The tropical nature of the state's flora is supported by the R/P and R + C/P indices of Feldman (1937) and Cheney (1997) with these ratios being 3.6 and 5.8, respectively. Florida's seaweed diversity is enhanced by the extensive salt marsh and seagrass communities of the west coast, plus the coral reef habitats of the Florida Keys. The present review summarizes several important historical studies, conspicuous geographic patterns, the type of communities, and the structure of a guide to the seaweeds of Florida. The guide will also serve as a historical reference for possible anthropogenic impacts in the future.
Assessing the Biodiversity of Monoraphidium Using 18S rDNA Sequences
Authors: Fawley M. W. , Fawley K. P. , Dean M. L.
Published: March 2003

The taxonomy of the genus Monoraphidium is unclear due in part to the absence of morphological features to clearly distinguish one species from another. Phytoplankton samples collected from lakes in the Arrowwood National Refuge in eastern North Dakota were found to contain several morphological species of Monoraphidium. Eighteen Monoraphidium isolates were examined with light microscopy and six morphological species were identified. PCR–RFLP of the 18S rDNA was used to type the isolates. Following digestion by Hae III and Taq I, the 18S rDNA PCR–RFLP patterns indicated 10 different types. Presently, the 18S rDNA product is being sequenced for each of the 10 types. By examining morphological characters and 18S rDNA sequences, congruence between morphology and sequence data may be compared. Also, because there is a lack of morphological characters defining Monoraphidium species, diversity within the 18S rDNA sequences may aid in the taxonomy of the genus and its place within the Chlorococcales. Supported by National Science Foundation Grants MCB‐0084188 and DBI‐0070387.
The Central American Isthmus: Implications for Intraspecific Phylogeny and Biogeography of a Pantropical Green Alga
Authors: Wysor B.
Published: March 2003

An intraspecific phylogenetic study was undertaken to resolve the evolutionary relationship of isolates of the green alga Phyllodictyon anastomosans (Harv.) Kraft et Wynne that occur on Atlantic and Pacific coasts of the Central American Isthmus. Patterns of vicariance related to the emergence of the Central American Isthmus were evident, but numerous examples of recent trans‐oceanic and trans‐isthmian dispersal obscured the underlying pattern. This study, one of the first studies to assess the impact of the emergence of the Central American Isthmus in seaweed phylogeography, provided an ideal opportunity to estimate the rate of sequence evolution using a single time point. Using this newly calibrated molecular clock the timing of an historical introduction across the isthmus is shown to be concordant with a shallow water breach of the isthmus dated at approximately 2.3–2.0 million years ago. This work contributes to a growing body of literature that suggests marine algae are fairly successful at dispersing over long distances in recent times.
A Survey of the Offshore Marine Macroalgae From the North‐Western Gulf of Mexico Hard Bank Communities
Authors: Fredericq S. , Cho T. O. , Gavio B. , Gurgel C. F. , Hickerson E. , Lin S. M. , Lopez‐Bautista J. , Phillips N. , Viguerie M. , Wysor B.
Published: March 2003

The upper north‐western Gulf basin is characterized by a relatively shallow but well‐developed continental shelf with an extensive system of mid‐ and outer shelf hard banks formed on unique tectonically created salt diapirs of varying origin and composition. Observations done by our laboratory while participating in monitoring cruises to the National Marine Sanctuaries of the E and W Banks of the Flower Gardens (TX), Stetson Banks (TX), Sonnier Banks (LA) and dredging cruises off Louisiana reveal a surprisingly different floristic composition among the sites. Several range extensions, new macroalgal records for the Gulf of Mexico, and new species imply a much more complex algal community than previously documented. Our ongoing project includes the development of a modern taxonomic, phylogenetic and morphological database essential to informed management for preservation of biological diversity. It also provides a framework of seasonal algal composition against which long‐term trends and anomalies in algal distribution and health of the Gulf of Mexico can be assessed at future dates.
Grateloupia Turuturu (Halymeniaceae, Rhodophyta): The Correct Identity of the Invasive Species in the Atlantic Known as Grateloupia Doryphora as Inferred From Molecular and Morphological Evidence
Authors: Gavio B. , Fredericq S.
Published: March 2003

Grateloupia doryphora (Montagne) Howe, originally described from Peru, has repeatedly been reported as an invasive species in Atlantic and Mediterranean waters. Various attempts to explain this species' route of invasion have, so far, been unsatisfying. In the present paper, we provide new evidence on the basis of comparative rbcL sequence analysis and morphology that this invasive species in the NE and NW Atlantic corresponds to G. turuturu Yamada, originally described from Japan. The true origin of this alga follows a well‐recognized trend of invasive marine organisms that have on various occasions colonized the Atlantic and Mediterranean Sea from Pacific NE Asia.
Endemism and Invasion in the Great Lakes Diatom Community
Authors: Kreuger N. , Julius M. L.
Published: March 2003

Population dynamics and health for individual Great Lakes diatom species is explored. Information dealing with how these taxa compete with introduced species and rapid environmental changes in modern times is examined. Diatomists have identified a number of these taxa, but discussion is limited with little or no information covering the ecological range of the taxa over time. Some of these include Cyclotella americana Fricke; C. bodanica var. stellata Skvortzow; and Stephanodiscus superiorensis Theriot. A number of taxa endemic to the Great Lakes undescribed in the literature also exist. These are species wedged into taxonomic categories from the European taxonomic system. Recent advances in the understanding of diatom species boundaries, suggest these names are inappropriately used for a number of taxa identified in paleolimnological investigations of the Great Lakes. This problem developed because taxonomic information outside of the European flora is not readily available to researchers, and because the focus of paleolimnological studies is primarily environmental reconstruction minimizing the time that can be spent unraveling taxonomically troublesome species. Examples of these are Cyclotella bodanica var. glabriscula and C. bodanica var. oligactis. Great Lakes populations of these taxa are significantly different from the original populations described from alpine lakes in Austria and Switzerland and merit taxonomic separation. Many of the endemic taxa are no longer present in the modern Great Lakes assemblages. The precise time of their disappearance from the system is not know, but modifications in Great Lakes diatom populations clearly coincided with the development of substantial European settlement of the Great Lakes region. C. americana, for example, was always limited to Lakes Erie and Ontario but disappeared from both of these lakes prior to 1900. With the disappearance of these taxa, came a number of introductions to the lakes. This work represents the first attempt to document these floristic changes.
Preservation of Nostocacean Hormogone Motility in Desiccated Calcium Carbonate Agar Patches
Authors: Lazaroff N.
Published: March 2003

Filamentous nitrogen fixing cyanobacteria are resistant to desiccation, nutrient depletion, adverse temperature and challenging photic environments. This is generally thought to account for their role as pioneering forms of life on denuded strata. It has also lent credence to the possibility that cyanobacteria with prolonged viability may have been able to survive conditions of interplanetary space to implement a panspermian hypothesis for the origin of life on earth. Prolonged retention of viability had been noted in our collection of myxotrophically grown strains of nostocaceans cultured in liquid or solid media containing calcium carbonate. Such media permitted satisfactory recovery and regrowth after storage at low light intensities for 2 years or more. Moreover, even the oldest calcium carbonate cultures contained motile hormogonia when observed microscopically. This phenomenon can be used to advantage in sending cultures to other laboratories. Not only are organisms maintained during passage through the postal system but since the cultures formed hormogonia readily, it was possible to produce preservable homogeneous agar lawns that generated hormogonia as needed for demonstration or experiment. A practical technique consists of seeding axenic strains of Nostoc species grown in liquid shake culture under cool‐white fluorescent illumination into solid media containing 0.7% sucrose, 0.05% finely divided calcium carbonate and 1.4% purified agar. The preparations are incubated under red fluorescent illumination to produce several crops of hormogonia in successive cycles of development, within the agar. The heavily grown lawns are cut into disks or squares, then transferred to dishes and dried in desiccators with anhydrous calcium sulfate. The dry patches produce swarms of hormogonia in 2 or 3 h, depending upon the rate of rehydration. The patches are facile tools for purifying cultures through the isolation of hormogonia and studying cyanobacterial physiology by the rapid response of motile hormogonia.
Phylogeography of Batrachospermum Helminthosum (Rhodophyta) in North America
Authors: Chiasson W. B. , Machesky N. J. , Vis M. L.
Published: March 2003

The freshwater red alga, Batrachospermum helminthosum, is distributed primarily in streams of eastern North America. Although it is often an abundant and conspicuous component of the algal flora for many streams, little is known about the genetic relationship among populations throughout its range. The purpose of our study was to elucidate geographic patterns among populations to gain insight into the biogeographic distribution of this species and possible modes of dispersal. Individuals were sampled in 13 stream segments as follows: four locations in Ohio, two locations in Michigan and one location each in Indiana, North Carolina, Tennessee, Louisiana, Rhode Island, Massachusetts and Connecticut. The mitochondrial spacer region (371 bp) between the COX2 and COX3 genes was chosen because it is variable among individuals. This region was sequenced for 15 individuals from each location. Thirteen haplotypes were identified among the 13 locations with most locations having one or two haplotypes. Two of the haplotypes were dominant being recorded from six of the streams. The Indiana, Louisiana and first Michigan population had a unique haplotype. The second Michigan and fourth Ohio populations shared a unique haplotype. The Tennessee population had four haplotypes, three of which were closely related but the fourth haplotype was not and linked to the haplotypes from Michigan and Ohio. The relationships among these populations are very complex but there may have been a recent dispersal event via birds among various streams.
Interannual Variation in Coral Reef Plant Communities of Central Belize
Authors: Rhodes M. J. , Nelson T. A.
Published: March 2003

Algal and seagrass community composition were monitored biennially along three transect lines in Belize from 1997 through 2001. Two sites were on South Water Caye. The first was on the seaward side, between the reef crest and the caye. The second was on the landward side of the caye. The third site was on Long Caye, Glover's Reef Atoll. This transect line ran from a coral rubble filled embayment, through a small channel (formed by hurricane Hattie in 1960, bisecting Long Caye), and into a seagrass meadow in the interior of the atoll. After a 38‐year hiatus, hurricanes struck Belize in 1998, 2000 and 2001, giving us the opportunity to examine changes in plant community structure before and after the storm sequence. Minimal interannual changes were seen at South Water Caye. The seagrasses at Long Caye were nearly eliminated along the transect line due to burial by sand. Peak density of Thalassia testudinum at Long Caye was over 60 shoots/m2 in 1997 and less than 2 shoots/m2 in 1999 and 2001. Halodule wrightii and Syringodium filiforme were both completely eliminated between 1997 and 1999. Padina and Dictyota spp. flourished in the embayment following the hurricane, but had been virtually absent prior to the sequence of storms. Future monitoring will be conducted to follow recovery of the meadow and look for other long‐term changes.
Photoprotective Compounds in Rice‐Field Cyanobacteria
Authors: Sinha R. P. , Haeder D.‐P.
Published: March 2003

Cyanobacteria are cosmopolitan in distribution, forming a prominent component of microbial populations in both aquatic as well as terrestrial ecosystems. They are the dominant microflora in rice‐fields, where they significantly contribute to fertility as a natural biofertilizer. The fluence rates of UV‐B radiation impinging on the natural habitats is of major concern since being photoautotrophic organisms, cyanobacteria depend on solar radiation as the primary source of energy. UV‐B radiation causes reduction in growth, survival, pigment and protein content, heterocyst frequency and fixation of carbon and nitrogen in cyanobacteria. However, a number of cyanobacteria synthesize water soluble colorless mycosporine‐like amino acids (MAAs) and the lipid soluble yellow‐brown colored sheath pigment, scytonemin to counteract the damaging effects of UV‐B. Anabaena sp., Nostoc commune, Scytonema sp. and Lyngbya sp. were isolated from rice‐fields in India and screened for the presence of photoprotective compounds. Spectroscopic and biochemical analyses revealed the presence of shinorine, a bisubstituted MAA containing both glycine and serine group with an absorption maximum at 334 nm in all cyanobacteria except Lyngbya sp. There was a circadian induction in the synthesis of this compound by UV‐B. Polychromatic action spectra for the induction of MAAs in Anabaena sp. and N. commune show the induction to be UV‐B dependent peaking at 290 nm. Another photoprotective compound, scytonemin, with an absorption maximum at 386 nm (also absorbs significantly at 300, 278, 252 and 212 nm) was detected in all cyanobacteria except Anabaena sp. In addition, two unidentified, water‐soluble, yellowish and brownish compounds with an absorption maximum at 315 nm were recorded only in Scytonema sp. The spectral characteristics of these compounds neither matches with MAAs nor with scytonemin and seems to be a novel compound acting as an effective UV screens. In conclusion, a particular cyanobacterium having photoprotective compounds may be a potent candidate as biofertilizers for crop plants.