bluuebunny/crossref_metadata_2025 huggingface dataset:
DETECTION OF NEW PIGMENTS FROM EMILIANIA HUXLEYI (PRYMNESIOPHYCEAE) BY HIGH‐PERFORMANCE LIQUID CHROMATOGRAPHY, LIQUID CHROMATOGRAPHY–MASS SPECTROMETRY, VISIBLE SPECTROSCOPY, AND FAST ATOM BOMBARDMENT MASS SPECTROMETRY
Authors: Garrido José L. , Zapata Manuel
Published: March 2003

Pigment extracts from Emiliania huxleyi (Lohm.) Hay et Mohler (strains CCMP 370, CCMP 373, and NIOZ CH 24) were analyzed using high‐performance liquid chromatography (HPLC) on highly efficient monomeric and polymeric octadecylsilica columns using either ammonium acetate or pyridine containing mobile phases. Both systems showed chromatographic profiles with peaks corresponding to pigments of uncertain structure: those of the polar and nonpolar chlorophyll c forms and one peak whose on‐line diode array spectrum resembled that of the fucoxanthin acyloxy derivatives. Liquid chromatography coupled with atmospheric pressure chemical ionization mass spectrometry gave a molecular mass of 786 units for the unknown carotenoid. The pigments corresponding to each of these fractions were isolated and their visible spectra recorded in various solvents. Samples of the isolated pigments were subjected to analysis by fast atom bombardment mass spectrometry that confirmed a molecular mass of 786 for the unknown carotenoid and gave a mass of 654 units for the polar chlorophyll c3, compatible with the monovinylic structure previously suggested. The detection of these new pigments calls for attention on the use of correct methodologies when HPLC pigment signatures are used to study the taxonomic composition of natural phytoplankton populations.
TIMING AND LIGHT REGULATION OF APICAL MORPHOGENESIS DURING REPRODUCTIVE DEVELOPMENT IN WILD‐TYPE POPULATIONS OF ACETABULARIA ACETABULUM (CHLOROPHYCEAE)
Authors: Kratz René F. , Young Philip A. , Mandoli Dina F.
Published: March 2003

In the giant unicellular green alga, Acetabularia acetabulum (L.) Silva, development is altered by light. For example, blue light induces the vegetative apex to produce whorls of hairs that encircle the stalk and, later, blue light may trigger reproductive onset. The two goals of this study were to determine when changes in apical shape occur during formation of the reproductive structure, or “cap,” and to determine which of these differentiation events require light. The first visible indication of cap initiation was a rounded swelling of the apex, which we call a knob‐shaped apex (time = 0 hours). Subsequent changes in shape were a hyaline, knob‐shaped apex, reached by 50% of the population 3 h later, and the formation of a whorl of unilobed chambers at 16 h. These chambers became bilobed at 33 h and trilobed at 34 h. Successive sets of cap hairs grew from protuberances found on the surface of the uppermost lobes of the chambers (superior corona). After knob, the remainder of cap formation was largely independent of light. However, the initiation of each set of cap hairs required light. If a recently initiated cap was amputated, the individual recapitulated development, repeating a portion of vegetative morphogenesis (i.e. it made whorls of sterile hairs) before initiating a new cap. The developmental sequence between amputation and initiation of a new cap required light. A model for light‐regulated changes in shape at the apex of Acetabularia acetabulum, which integrates whorl and cap formation and encompasses both vegetative and reproductive development of this organism, is presented.
FINE STRUCTURE OF DWARF MALES IN OEDOGONIUM PLUVIALE (CHLOROPHYCEAE)
Authors: Leonardi Patricia I. , Cáceres Eduardo J. , Vélez Carlos G.
Published: March 2003

Oedogonium pluviale Nordstedt is nannandrous, described as possessing single‐celled dwarf males. In some studies the dwarf males appear to have a reduced, lens‐shaped pedicular portion whose nature and structure remain unclear. The present study aims to: 1) establish whether dwarf males of O. pluviale are single‐ or two‐celled, 2) describe the different developmental stages of dwarf males, and 3) understand the nature of the pedicular portion. Mitotic division of the dwarf male was observed, but neither upwards phycoplast migration nor synthesis of a gametangial cell wall occurred. Instead, the phycoplast and cell plate migrated downwards, producing a small pedicular portion whose content then degenerated. The antheridium occupied most of the dwarf male wall. Gametogenesis thus took place inside the wall of the young dwarf male (internal gametangium). Because the pedicular cell degenerated, we define this type of dwarf male as pseudo‐single‐celled to differentiate it from a true single‐celled dwarf male. The antheridial nucleus underwent one mitotic division to give rise to two gametes. Instead of a true wall between gametes, mucilage condensed and was observed as a discrete layer that disappeared during gamete release.
TAXONOMY AND ULTRASTRUCTURE OF A FRESHWATER, HETEROTROPHIC AMPHIDINIUM (DINOPHYCEAE) THAT FEEDS ON UNICELLULAR PROTISTS
Authors: Calado António J. , Craveiro Sandra C. , Moestrup Øjvind
Published: March 2003

Amphidinium lacustre Stein, non sensu auctt. was identified by reference to original descriptions, which differ significantly from later interpretations. Mixed cultures containing A. lacustre, cryptomonads, Spermatozopsis exsultans Korshikov, and small chlorelloid cells were examined for feeding events. The dinoflagellate ingested the cytoplasm of cryptomonads, leaving the periplast, and completely ingested Spermatozopsis and chlorelloid cells. A peduncle was used in the initial stages of prey capture, although it was not visible during food uptake. The ultrastructure of A. lacustre was typical of unarmored dinoflagellates. A single pusule per cell, consisting of one long, convoluted tube, opened directly into one of the flagellar canals. An eyespot was present, composed of presumably crystalline, vesicle‐contained units, similar to those of Gymnodinium natalense Horiguchi et Pienaar. The main components of the flagellar apparatus resembled those of other Amphidinium species, but differences were noted. The transverse basal body overlapped the proximal end of the longitudinal one at an angle of about 120°. Three connectives were distinguished between basal bodies, one of which consisted of radiating fibers linking individual triplets of the longitudinal basal body to one triplet of the transverse. Some flagellar apparatus components were closely associated to a vesicle and to a mitochondrion. A ventral ridge extended from the (incomplete) longitudinal striated collar to the peduncular striated collar. The peduncle was supported by a single strand of microtubules, which were surrounded by numerous vesicles with electron‐opaque contents.
THE UBIQUITOUS PRESENCE OF CHLOROPHYLL D IN RED ALGAE FROM THE MONTEREY PENINSULA
Authors: Landráu M.E. , Welschmeyer N.A.
Published: March 2003

The presence of chlorophyll d in red algae has been a subject of great controversy, however, only a few studies have been devoted to this subject, and evidence for its existence has been inconsistent. Here we report on results of a survey of 56 species of red macroalgae from central California, 3 species from Baja California Sur, Mexico, and 2 species from Cape Evans, Antarctica. Chlorophyll d was detected in 48 of the California species, 1 of the Mexico species, and 1 of the Antarctica species. Chlorophyll a/d ratio ranged from 6 to 21123. The fraction of species of red algae containing chlorophyll d was higher in samples collected in October (36 out of 36), than those collected in June (12 out of 29) or March (4 out of 22). Chlorophyll d was not detected in any of the brown or green macroalgae analyzed. In vivo absorption spectra of Gelidium sp. were collected, and resolution of these spectra by fourth derivative resulted an absorption maximum at 687 nm due to chlorophyll a, and at 719 nm due to chlorophyll d. Extracted pigment of Gelidium sp. in 90% acetone had an absorption maximum of 664 nm, and a smaller absorption peak at 692 nm. Fluorescence emission and excitation spectra resulted in a maximum of 699 nm and 447 nm, respectively. The emission peak wavelength of 699 and an absorption peak longer than that of chlorophyll a (699 nm compared to 664 nm) suggest chlorophyll d may serve as a light‐harvesting pigment in photosynthesis.
THE PHYLOGENETICS OF ACROCHAETIALES REVISITED: INFERENCES FROM RBCL AND CHLOROPLAST ENCODED 23S RRNA SEQUENCE ANALYSIS
Authors: Volovsek M.E. , Hommersand M.H. , Manos P.
Published: March 2003

Recent molecular evidence from 23S rRNA sequences has shed light on the phylogenetic status of Acrochaetiales and Palmariales, suggesting a paraphyletic Acrochaetiales and a monophyletic Palmariales‐Acrochaetiales assemblage characterized by the absence of both the carpogonial filament and associated post‐fertilization fusions. It has also brought into question the status of Palmariales. Despite these findings, the familial and generic systematics of Acrochaetiales have remained somewhat obscure, in large part due to inadequate taxon and gene sampling. In the present study we address this problem by performing phylogenetic analyses of rbcL and 23S rRNA sequences from acrochaetioid algae covering a broad range of morphologies. Our results confirm elements from several primarily chloroplast based classification schemes (Papenfuss 1945, 1947; Stegenga 1979, 1985; Lee & Lee 1988) while also providing new phylogenetics insight. Two groups are supported at the most inclusive level. Group I is marine, has parietal chloroplasts, and includes three clades delimited primarily by the presence/absence of pyrenoids, number of chloroplasts, and possibly spore germination pattern. Group II is more heterogeneous and consists of three clades differentiated largely by chloroplast type (stellate/parietal, pyrenoid present/absent) and number, habitat (marine/freshwater) and life history. Systematic criteria drawn from the closely related order Palmariales suggest that we recognize Group I as a new family, Colaconemataceae, and the three taxa in Group II as Acrochaetiaceae, Rhodochortonaceae and Audouinellaceae. Furthermore, each of the three groups in Colaconemataceae could be regarded at the generic level. We also report on the utility of 23S rRNA for red algal systematics.
NUTRIENTS DO NOT INFLUENCE SWIMMING BEHAVIOR OR SETTLEMENT RATES OF ECTOCARPUS SILICULOSUS (PHAEOPHYCEAE) SPORES
Authors: Amsler Charles D. , Shelton Kisha L. , Britton Christopher J. , Spencer Netanya Y. , Greer Stephen P.
Published: March 2003

Spores newly released from plurilocular sporangia of Ectocarpus siliculosus (Dillw.) Lyngb. sporophytes were assayed for chemotaxis to nutrients and for settlement stimulation by nutrients. To enable these measurements with relatively small volumes and numbers of released spores, we developed a computer‐assisted motion‐analysis assay for spore chemotaxis and verified the results with a more standard, capillary tube chemotaxis assay. The presence of a nutrient gradient did not influence the swimming behavior of E. siliculosus spores in the motion‐analysis assay, and likewise no chemotactic effect was measured in the capillary tube assay. Microplate settlement assays previously utilized with bacteria and invertebrates were adapted for use with algal spores. E. siliculosus spores settled at higher rates on a hydrophobic plastic surface than on surfaces with either positively or negatively charged hydrophilic coatings. Nutrient mixtures had no effect on the rate of spore settlement on hydrophobic surfaces.
ANALYSIS OF CLONAL CULTURES OF THE BROWN TIDE ALGAE AUREOCOCCUS AND AUREOUMBRA (PELAGOPHYCEAE) USING 18S rRNA, rbcL, AND RUBISCO SPACER SEQUENCES
Authors: Bailey J. Craig , Andersen Robert A.
Published: March 2003

Variability among clonal cultures of the brown tide algae Aureococcus anophagefferens Hargraves et Sieburth and Aureoumbra lagunensis Stockwell, DeYoe, Hargraves et Johnson was examined by DNA sequence comparisons. Nuclear‐encoded 18S rRNA and plastid‐encoded rbcL gene sequences were determined for six Aureococcus strains. RUBISCO spacer sequences were determined for 14 strains of Aureococcus. No differences among Aureococcus strains were found in the DNA regions examined. The rbcL and RUBISCO spacer sequences for three Aureoumbra strains were identical but differed from those of Aureococcus. These data indicate that blooms of these species are comprised of cells that are very similar and also imply that Aureococcus and Aureoumbra do not contain varieties or cryptic species. Separate and combined phylogenetic analyses of the 18S rRNA and rbcL gene sequences were performed. Results confirm that the brown‐tide‐causing algae of Long Island Sound, New York (Aureococcus), and Laguna Madre, Texas (Aureoumbra), are best classified in separate genera within the Pelagophyceae. Phylogenetic trees place Aureococcus and Aureoumbra within the Pelagomonadales and Sarcinochrysidales, respectively.
PHOTOSYNTHETIC RESPONSE OF STREAM PERIPHYTON TO FLUCTUATING LIGHT REGIMES
Authors: Wellnitz Todd , Rinne Bettina
Published: March 2003

An experiment was conducted on intact algal assemblages of stream periphyton to test their response to fluctuating and constant light regimes having the same mean intensity. The light regimes (in μmol·m−2·s−1) were constant light at 100, light fluctuating between 50 and 150 with a period of 5 min, and light fluctuating between 10 and 460 with periods of either 4:1 or 8:2 min. Compared to the rates measured under 100 in μmol·m−2·s−1 constant light conditions, fluctuations ranging between 50 and 150 in μmol·m−2·s−1 with a 5‐min period produced a 23% greater rate of photosynthesis. Conversely, fluctuations between 10 and 460 in μmol·m−2·s−1 led to a 59%–74% decrease in photosynthetic activity. Detailed examination of periphytic algal responses to fluctuating light revealed that higher light intensities produced steeper photosynthesis/time slopes, but it was the combined interaction with lower light intensity that ultimately determined overall photosynthetic rate for a given light regime. This study offers compelling evidence that variable light regimes have important consequences for algal photosynthesis in natural streams.
ACCUMULATION OF SULFURIC ACID IN DICTYOTALES (PHAEOPHYCEAE): TAXONOMIC DISTRIBUTION AND ION CHROMATOGRAPHY OF CELL EXTRACTS
Authors: Sasaki Hideaki , Kataoka Hironao , Kamiya Mitsunobu , Kawai Hiroshi
Published: March 2003

Four species in the order Dictyotales (Dictyopteris latiuscula (Okamura) Okamura, D. prolifera (Okamura) Okamura, D. repens (Okamura) Børgesen, and Spatoglossum crassum J. Tanaka) were found to be highly acidic as in some species of the order Desmarestiales (Phaeophyceae). The pH within their cells, presumably that of the vacuole, was estimated to be 0.5 to 0.9 by pH measurements of their cell extracts in distilled water. However, other species of these genera (D. divaricata (Okamura) Okamura, D. undulata Holmes, and S. pacificum Yendo) did not show high acidity. Ion chromatography of the cell extracts showed that those species contained high concentrations of SO within their cells, up to 10 times that in seawater but relatively low Cl−. The sum of cations examined (Na+, NH, K+, Mg2+, Ca2+) was significantly lower than that of anions (Cl−, Br−, NO, SO), and the difference is presumed to represent protons (H+), causing the extremely low cell sap pH. Estimated cellular proton concentrations calculated from the pH data roughly agreed with those calculated from differences between the sum of cations and anions and that of anions. Although certain other, nonacidic, dictyotalean species also contained high concentrations of SO, these species contained high concentrations of Mg2+, and the sums of cations and anions were balanced.
WIDESPREAD OCCURRENCE OF THE OCEANIC ULTRAPLANKTER, PRASINOCOCCUS CAPSULATUS (PRASINOPHYCEAE), THE DIAGNOSTIC “GOLGI‐DECAPORE COMPLEX” AND THE NEWLY DESCRIBED POLYSACCHARIDE “CAPSULAN”
Authors: Sieburth John McN. , Keller Maureen D. , Johnson Paul W. , Myklestad Sverre M.
Published: March 2003

A nonmotile green nanoalga was isolated from the waters over the Cayman Trench in March 1979 and has been maintained in culture as clone URI 266G (CCMP 1202). It was observed to form a copious polysaccharide capsule that presumably originated in the Golgi body and was secreted through a crown of 10 pores in the cell wall, the “decapore.” This multilaminate apical area, lying adjacent to the Golgi, underwent structural changes during morphogenesis. The polysaccharide precursors that coalesced to form the capsule apparently became stainable and visible as they exited the decapore when they cross‐linked with divalent ions in seawater. Cell wall precursors, or a cell wall lamina, surrounded the daughter cells both during synchronous binary fission and after cell separation, with the maternal capsule perhaps acting as a template. Similar prasinophyte isolates have been obtained from widespread areas of the North Atlantic and were divided into two subgroups on the basis of their pigment complement (Hooks et al. 1988). One subgroup, typified by clone Ω 48‐23 (CCMP 1203), was described by Guillard et al. (1991) as Pycnococcus provasolii Guillard within a new family, the Pycnococcaceae. The other subgroup, typified by clone URI 266G (CCMP 1202), contained two unique carotenoids, one of which was uriolide (Foss et al. 1986). Subsequently, Miyashita et al. (1993) described an alga from the western Pacific Ocean that is indistinguishable from URI 266G in both pigment composition and ultrastructure that they named Prasinococcus capsulatus Miyashita et Chihara and placed tentatively in the Pycnococcaceae. They described a curious asexual budding fission. Here we suggest an alternative form of cell division analogous to that observed in the other described Pycnococcaceae. We used theultrastructure of cells in exponential and stationary phases of growth to illustrate synchronous asexual binary fission, the “Golgi‐decapore complex,” and its apparent role in capsule formation. A unique sulfated and carboxylated polyanionic polysaccharide named capsulan is released from this complex.
CONVERGENT BIOLOGICAL PROCESSES IN COALESCING RHODOPHYTA
Authors: Santelices Bernabé , Correa Juan A. , Aedo Diego , Flores Verónica , Hormazábal Marcela , Sánchez Pablo
Published: March 2003

Sporeling coalescence in Gracilaria chilensis Bird, McLachlan et Oliveira produces genetically polymorphic, chimeric individuals. If this is common in red algae, it may have significant biological consequences. In this study, we evaluate the hypotheses that coalescence is widespread among the Rhodophyta and that specific and convergent morphological and ecological responses characterize this as a unique growth style among marine algae. A literature survey on coalescence was undertaken to assess the distribution of this condition in the Florideophycidae. Sixty‐two (54.9%) of 113 species considered germinated to form a disk. Subsequent development in 37 of these species showed crust formation and coalescence during development with other crusts in 31 species (84%). Coalescing red algae were members of the orders Ahnfeltiales, Corallinales, Gigartinales, Gracilariales, Halymeniales, Palmariales, and Rhodymeniales. Ultrastructural studies in species of Ahnfeltiopsis, Chondrus, Gracilaria, Mazzaella, and Sarcothalia suggested a common pattern of early development. Newly released, naked spores may fuse into a single cell, as they do in Chondrus canaliculatus, or they may develop individual cell walls that later are surrounded by a thickened common wall. Ultrastructural studies demonstrated two kinds of immediate development after the first mitotic division: direct development by symmetric divisions resulting in discoid sporelings or an indirect asymmetric arrangement of divisions before a diskoid sporeling was formed. Germination in coalescing species is a linear function of the initial spore density, whereas in noncoalescing species maximum germination occurs at intermediate densities. In the field, coalescing species may recruit either from solitary or aggregated spores. However, survival is significantly higher for plantlets grown from a larger number of coalescing spores. Total number of erect axes formed by the coalesced mass is a logarithmic function of the initial number of spores. Thus, germlings grown from a larger number of coalescing spores exhibited a larger photosynthetic canopy than do plantlets grown from a few spores. Juveniles and mature clumps grown from a coalescing mass may exhibit size inequalities among erect axes, with the larger axes located toward the center of the clump. These larger axes mature first or, in some cases, are the only to produce spores. The widespread occurrence of coalescence inroughly half the number of orders of the Florideophycidae, the similarity of the coalescence process, and the finding of various adaptive traits associated with coalescence characterizes this as a unique growth style, splitting the diversity of species now included in the Florideophycidae into two major groups: coalescing and noncoalescing Rhodophyta.
ISOLATION AND CHARACTERIZATION OF SIX cDNAs INVOLVED IN CARBON METABOLISM IN LAMINARIA DIGITATA (PHAEOPHYCEAE)
Authors: Moulin Pascale , Crépineau Florent , Kloareg Bernard , Boyen Catherine
Published: March 2003

An expressed sequence tag (EST) approach was used to retrieve cDNA clones involved in carbon metabolism in Laminaria digitata Lamouroux. Six partial open reading frames were identified, respectively encoding an α‐type carbonic anhydrase (CA), glucose‐6‐phosphate dehydrogenase (G6PDH), 6‐phosphogluconate dehydrogenase (6PGDH), phosphoglycerate kinase (PGK), glycolate oxidase (GLO), and GDP‐4‐keto‐6‐d‐mannose‐3,5‐epimerase‐4‐reductase, also known as fucose synthase (FS). These enzymes were further characterized through Southern blot analyses, amino acid sequence comparisons, and patterns of expression. In contrast to the other genes, which are expressed in both the gametophytic and sporophytic generations of L. digitata, the α‐type carbonic anhydrase messenger RNA was shown by RT‐PCR and northern blot analyses to be present in the gametophytes only. The evolutionary relationships of these genes and their interest as molecular tools for investigating carbon fluxes in brown algae are discussed.
ADAPTATION OF SCENEDESMUS OBLIQUUS (CHLOROPHYCEAE) TO COPPER‐DEFICIENCY: TRANSCRIPTIONAL REGULATION OF PCY1 BUT NOT CPX1
Authors: Quinn Jeanette M. , Merchant Sabeeha
Published: March 2003

In contrast to the situation in Chlamydomonas reinhardtii, plastocyanin expression in the green alga Scenedesmus obliquus (Turp.) Kütz. (Chlorophyceae) is regulated by copper ion availability at the level of both protein and mRNA accumulation. To study the mechanism of copper‐dependent mRNA accumulation, plastocyanin‐encoding genomic and cDNA clones have been isolated and sequenced. The single nuclear S. obliquus Pcy1 gene contains two introns and a bipartite transit peptide sequence typical of plastid lumen‐localized proteins. Despite the similarity of the S. obliquus and Chlamydomonas reinhardtii Pcy1 genes, the S. obliquus Pcy1 gene was not expressed from its own promoter, nor could the S. obliquus Pcy1 promoter drive expression of a C. reinhardtii gene when it was introduced into the genome of C. reinhardtii cells. Using the cDNA clone as a probe, copper‐responsive regulation of Pcy1 expression was further characterized in S. obliquus. Experiments examining the time course of Pcy1 degradation on depletion of copper argue against a specific mechanism for Pcy1 mRNA decay in S. obliquus, suggesting that the copper‐responsive change in abundance occurs through transcriptional regulation. The Cpx1 gene (encoding coproporphyrinogen III oxidase) also responds differently to changes in cellular copper status in S. obliquus compared to C. reinhardtii. Whereas Cpx1 is highly induced in copper‐deficient cultures of C. reinhardtii, in S. obliquus the Cpx1 gene is not copper responsive.
MADS‐BOX GENES: DEVELOPMENT AND EVOLUTION OF PLANT BODY PLANS
Authors: Vergara‐Silva Francisco , Martínez‐Castilla León , Alvarez‐Buylla Elena R.
Published: March 2003

We review functional data on MADS‐box genes, recent phylogenetic analyses of these coding regions, and their roles in the development and evolution of key morphological innovations in plants. We map the origin of important morphological structures in particular diverse stages of the life cycle in different plant clades onto organismal phylogenies, and present relevant molecular genetic aspects of development related to the MADS‐box genes. We focus on reproductive structures of the sporophyte because most functional characterizations have been done of MADS‐box genes involved in flower development. We discuss MADS‐box evolution in flowering plants, but we also review studies in the other nonflowering vascular plants, gymnosperms (conifers and gnetales), and ferns and preliminary data from the algae. We suggest that floral (e.g. flowering time, inflorescence, and flower meristem identity) MADS‐box and nonfloral plant MADS‐box genes should be the focus of future comparative research. Cloning and functional analyses of MADS‐box genes in bryophytes, particularly in the experimental system Physcomitrella patens (Hedw.) B.S.G., are needed. The ABC model of floral organ specification is an excellent general representation of an important network of genes; however, formal analytical tools are required to integrate data on complex gene interaction in comparative analyses. This and other analytical approaches to constructing gene network models will help to frame homology hypotheses in an evolutionary and developmental framework.
Photosynthetic light‐response curves and photoinhibition of the deep‐water laminaria abyssalis and the intertidal laminaria digitata (phaeophyceae)
Authors: Rodrigues Marcoaurélio Almenara , Dos Santos César Pereira , Yoneshigue‐Valentin Yocie , Strbac Dragana , Hall David Oakley
Published: March 2003

Photosynthetic light‐response curves of the deep‐water Laminaria abyssalis Oliveira and of the intertidal L. digitata Lamoroux were determined and related to photoinhibition phenomena as monitored by oxygen evolution and photosystem II efficiency (FV/FM). L. abyssalis has half the pigment content, number of cells and plastids, and photosynthetic capacity per unit area compared with L. digitata. L. abyssalis showed a higher in vivo Chl a absorption coefficient and higher photosynthetic efficiency on a Chl a basis, although the two algae showed somewhat similar light‐response curves on a Chl a basis. Both species showed similar Chl a/Chl c and Chl a/fucoxanthin ratios, and similar dark respiration rates and light compensation points. In addition, they also showed similar convexities in their light‐response curves and no differences in their light saturation of FV/FM. Room temperature chlorophyll fluorescence induction measurements of fronds incubated in 3‐(3,4‐dichlorophenyl)‐1,1‐dimethylurea (DCMU) suggest that both species may have a similar PSII absorption cross section. Thus, L. abyssalis appears to optimize its light absorption at very low light intensities, not by increasing the pigment content, but by absorbing light more efficiently. However, L. abyssalis was more sensitive to photoinhibition than L. digitata and showed no recovery of FV/FM and O2 evolution after a photoinhibitory treatment, even with a subsequent exposure to 24 h of dim light. L. digitata, on the other hand, recovered its photosynthetic capacity within 6 h under dim light. These results suggest that photosynthetic light‐induction curves based on Chl a are not a good indicator of either the photosynthetic capacity or the sensitivity to photoinhibition when macroalgae of different species are being compared. Based on their light‐response and photoinhibition characteristics, we suggest that L. abyssalis, a deep‐water oceanic macroalgae, is an atypical shade alga whereas L. digitata has the properties of a sun alga.
Pigment ratios and phytoplankton assessment in northern Wisconsin lakes
Authors: Descy Jean‐Pierre , Higgins Harry W. , Mackey Denis J. , Hurley James P. , Frost Thomas M.
Published: March 2003

Nine lakes in northern Wisconsin were sampled from February through September 1996, and HPLC analysis of water column pigments was carried out on epilimnetic seston. Pigment distributions were evaluated throughout the water column during summer in Crystal Lake and Little Rock Lake. The purpose of our study was to investigate the use of phytopigments as markers of the main taxonomic groups of algae. As a first approach, multiple regression of marker pigments against chlorophylla(chla) was used to derive the best linear combination of the main xanthophylls (peridinin, fucoxanthin, alloxanthin, lutein, and zeaxanthin). A significant regression equation (r2=0.98) was obtained for epilimnion data. The good fit indicates that the chla:xanthophyll ratios were fairly constant in the epilimnion of the nine lakes over time. Chlorophyllarecalculated from the main xanthophylls in each sample showed good agreement with measured chlain epilimnetic waters. A second approach used the CHEMTAX program to analyze the same data set. CHEMTAX provided estimates of chlabiomass for all algal classes and allowed distinction between diatoms and chrysophytes, and between chlorophytes and euglenophytes. These results showed a reasonably good agreement with biomass estimates from microscope counts, despite uncertainties associated with differences in sampling procedure. Changes of pigment ratios over time in the epilimnetic waters were also investigated, as well as differences between surface and deep samples of Little Rock Lake and Crystal Lake. We found evidence that changes in the ratio of photoprotective pigments to chlaoccurred as a response to changes in light climate. Changes were also observed for certain light‐harvesting pigments. The comparison between multiple regression and CHEMTAX analyses for inferring chlabiomass from concentrations of marker pigments highlighted the need to take account of variations in pigment ratio, as well as the need to acquire additional data on the pigment composition of planktonic algae.
METABOLIC RESPONSES OF THE DIATOM ACHNANTHES BREVIPES (BACILLARIOPHYCEAE) TO NUTRIENT LIMITATION
Authors: Guerrini Franca , Cangini Monica , Boni Laurita , Trost Paolo , Pistocchi Rossella
Published: March 2003

The diatom Achnanthes brevipes C.A. Ag. was cultured in the presence of limiting concentrations of nitrogen (N) or inorganic phosphate (Pi). Growth, in terms of final yield, was more affected by N limitation than Pi limitation; N limitation had a greater effect also on protein and chlorophyll content. Carbohydrate concentrations increased under both nutrient starvation treatments, but N or Pi limitation had different effects. Total (intracellular plus extracellular) sugar content increased when cells were exposed to both types of nutrient limitation, but the extracellular polysaccharide fraction increased only in the presence of Pi starvation. Analyses were performed to identify the metabolic changes occurring in cells exposed to low phosphate because this was the main condition that affected carbohydrate extrusion. Activities of several enzymes involved in carbohydrate metabolism showed that under Pi limitation there was no activation of alternative reactions that were found to result in Pi liberation, instead of its consumption, in some higher plants and in the green alga Selenastrum minutum Naeg. Collins. Results showed that activities of pyruvate kinase, phosphorylating NAD‐dependent 3‐phosphate‐glyceraldehyde dehydrogenase, and 3‐phospho‐glycerate kinase were inhibited under Pi‐limited conditions compared with control cells, indicating limited glucose catabolism. Activity of uridine diphosphate glucose pyrophosphorylase, a key enzyme for the biosynthesis of the storage compound crysolaminarin, was also partly inhibited in Pi‐stressed cells. Our findings suggest that carbohydrate catabolism in A. brevipes is limited under Pi deficiency, whereas extracellular extrusion of carbohydrate is favored.
PURIFICATION AND CHARACTERIZATION OF A SULFOTRANSFERASE SPECIFIC TO N‐21 OF SAXITOXIN AND GONYAUTOXIN 2+3 FROM THE TOXIC DINOFLAGELLATE GYMNODINIUM CATENATUM (DINOPHYCEAE)
Authors: Sako Yoshihiko , Yoshida Takashi , Uchida Aritsune , Arakawa Osamu , Noguchi Tamao , Ishida Yuzaburo
Published: March 2003

A sulfotransferase (ST) specific to N‐21 of saxitoxin (STX) and gonyautoxin 2+3 (GTX2+3) designated as N‐ST was purified to homogeneity from the cytosolic fraction of clonal‐axenic vegetative cells of the toxic dinoflagellate Gymnodinium catenatum Graham GC21V, which causes paralytic shellfish poisoning. The enzyme transferred a sulfate group from 3′‐phosphoadenosine 5′‐phosphosulfate (PAPS) to N‐21 in the carbamoyl group of STX and GTX2+3 to produce GTX5 and C1+2, respectively. The molecular mass of the purified enzyme was determined by SDS‐PAGE to be 59 kDa. Gel filtration chromatography showed a native molecular mass of 65 kDa, indicating that the N‐ST is a monomeric enzyme. The N‐ST was specific to only N‐21 of STX and GTX2+3, and O‐22 sulfation was not observed. Moreover, the N‐ST was not active toward neo STX and GTX1+4, which differed from STX and GTX2+3, respectively, in only N‐1 hydroxylation. When various compounds previously reported to be substrates for STs in other organisms and paralytic shellfish poisoning toxins other than STX and GTX2+3 were added to the reaction mixture, N‐ST activity was not decreased. The enzyme required PAPS as the sole source of sulfate. The enzyme was optimally active at pH 6.0 and 25° C, and its activity was enhanced by Mg2+ and Co2+. The Km values of the N‐ST for STX and GTX2+3 were 16.1 μM and 29.8 μM, respectively.
RHODOLITHS: BETWEEN ROCKS AND SOFT PLACES
Authors: Foster Michael S.
Published: March 2003

Rhodoliths (maërl) are widely distributed in the worlds' oceans and have an excellent fossil record. Individuals are slow growing, may be long lived (>100 years), and are resilient to a variety of environmental disturbances. Their external morphology and internal growth bands are potential archives of environmental variation at scales of within years to tens of years. At high densities, these free‐living non‐geniculate coralline algae form rhodolith beds, communities of high diversity that can be severely impacted by resource extraction.
EVIDENCE FOR METHYL JASMONATE‐INDUCED PHLOROTANNIN PRODUCTION IN FUCUS VESICULOSUS (PHAEOPHYCEAE)
Authors: Arnold Thomas M. , Targett Nancy M. , Tanner Christopher E. , Hatch Walter I. , Ferrari Kirstin E.
Published: March 2003

The plant growth regulators jasmonic acid and methyl jasmonate (MeJA) have recently been identified in a variety of marine algae; however, their role in these organisms is currently unknown. Here we report that exposure to MeJA, during periods of tidal emergence causes the induction of polyphenolic chemical defenses (the phlorotannins) in two populations of the common rockweed Fucus vesiculosus (Linnaeus). Phlorotannin concentrations were up to 1.6 times higher in the growing apices of F. vesiculosus from both Avery Point (Connecticut, USA) and Roosevelt Inlet (Delaware, USA) within 10–14 days after a single brief exposure to airborne MeJA at concentrations ranging from 5.42 to 542 nM. The timing and magnitude of this induced increase in phlorotannin concentration are similar to that caused by real and simulated herbivory, raising the question of whether jasmonates, or their oxylipin relatives, are natural elements of antiherbivore responses in Fucus, as they are in vascular plants.
INTEGRATING SEAWEEDS INTO MARINE AQUACULTURE SYSTEMS: A KEY TOWARD SUSTAINABILITY
Authors: Chopin Thierry , Buschmann Alejandro H. , Halling Christina , Troell Max , Kautsky Nils , Neori Amir , Kraemer George P. , Zertuche‐González José A. , Yarish Charles , Neefus Christopher
Published: March 2003

The rapid development of intensive fed aquaculture (e.g. finfish and shrimp) throughout the world is associated with concerns about the environmental impacts of such often monospecific practices, especially where activities are highly geographically concentrated or located in suboptimal sites whose assimilative capacity is poorly understood and, consequently, prone to being exceeded. One of the main environmental issues is the direct discharge of significant nutrient loads into coastal waters from open‐water systems and with the effluents from land‐based systems. In its search for best management practices, the aquaculture industry should develop innovative and responsible practices that optimize its efficiency and create diversification, while ensuring the remediation of the consequences of its activities to maintain the health of coastal waters. To avoid pronounced shifts in coastal processes, conversion, not dilution, is a common‐sense solution, used for centuries in Asian countries. By integrating fed aquaculture (finfish, shrimp) with inorganic and organic extractive aquaculture (seaweed and shellfish), the wastes of one resource user become a resource (fertilizer or food) for the others. Such a balanced ecosystem approach provides nutrient bioremediation capability, mutual benefits to the cocultured organisms, economic diversification by producing other value‐added marine crops, and increased profitability per cultivation unit for the aquaculture industry. Moreover, as guidelines and regulations on aquaculture effluents are forthcoming in several countries, using appropriately selected seaweeds as renewable biological nutrient scrubbers represents a cost‐effective means for reaching compliance by reducing the internalization of the total environmental costs. By adopting integrated polytrophic practices, the aquaculture industry should find increasing environmental, economic, and social acceptability and become a full and sustainable partner within the development of integrated coastal management frameworks.
IMMUNOLOCALIZATION OF AN α‐1,4‐GLUCAN LYASE IN YOUNG AND MATURE PARTS OF THE RED ALGA GRACILARIOPSIS SP. (RHODOPHYTA)
Authors: Camitz Astrid , Pedersén Marianne
Published: March 2003

The enzyme α‐1,4‐glucan lyase (EC 4.2.2.13) was studied in cells of young and mature parts of the red alga Gracilariopsis sp. by using immunogold labeling in ultrastructural studies. In young tissues, the α‐1,4‐glucan lyase was observed at two different sites: around the starch granules in the cytosol and in the stroma of the chloroplast. In mature tissues, the α‐1,4‐glucan lyase was present only in the chloroplasts. The possible role of this starch‐degrading enzyme in red algae is discussed.
RECENT ADVANCES IN FERTILIZATION ECOLOGY OF MACROALGAE1
Authors: Santelices Bernabé
Published: March 2003

Our understanding of natural patterns of fertilization in seaweeds has increased substantially over the last 10 years due to new approaches and methods to characterize the nature and frequency of fertilization processes in situ, to recognize the conditions and mechanisms enhancing fertilization success, and to anticipate population and community consequences of the patterns of natural fertilization. Successful reproduction in many species depends on a delicate juxtaposition of abiotic and biotic conditions. Important abiotic factors are those triggering gamete release (e.g. single or interacting effects of light quality and water movement) and those affecting gamete viability or concentrations (e.g. salinity effects on polyspermy blocks; gamete dilution due to water movement). Examples of important biotic components are synchronous gamete release, efficiency of polyspermy‐blocking mechanisms, population density of sexually fertile thalli, interparent distances, and male‐to‐female ratios. Field data indicate fertilization frequencies of 70%–100% in broadcasting‐type seaweeds (e.g. fucoids) and 30%–80% in brooding‐type (red) algae. Red algal values are higher than previously thought and challenge presently accepted explanations for their complex life histories. Important population and community questions raised by the recent findings relate to the magnitude of gene flow and exchange occurring in many micropopulations that seemingly breed during periods of isolation, the physiological basis and population effects of male‐to‐male competition and sexual selection during fertilization of brooding seaweeds, and the effects of massive gamete release, especially in holocarpic seaweeds, on benthic and planktonic communities. Comparative studies in other algal groups are now needed to test the generality of the above patterns, to provide critical pieces of information still missing in our understanding of natural fertilization processes, and to elucidate the evolutionary consequences of the different modes of reproduction (e.g. brooders vs. broadcasters).
ACCUMULATION OF OLEIC ACID IN HAEMATOCOCCUS PLUVIALIS (CHLOROPHYCEAE) UNDER NITROGEN STARVATION OR HIGH LIGHT IS CORRELATED WITH THAT OF ASTAXANTHIN ESTERS1
Authors: Zhekisheva Mirash , Boussiba Sammy , Khozin‐Goldberg Inna , Zarka Aliza , Cohen Zvi
Published: March 2003

The chlorophyte Haematococcus pluvialis accumulates large quantities of astaxanthin under stress conditions. Under either nitrogen starvation or high light, the production of each picogram of astaxanthin was accompanied by that of 5 or 3–4 pg of fatty acids, respectively. In both cases, the newly formed fatty acids, consisting mostly of oleic (up to 34% of fatty acids in comparison with 13% in the control), palmitic, and linoleic acids, were deposited mostly in triacylglycerols. Furthermore, the enhanced accumulation of oleic acid was linearily correlated with that of astaxanthin. Astaxanthin, which is mostly monoesterified, is deposited in globules made of triacylglycerols. We suggest that the production of oleic acid‐rich triacylglycerols on the one hand and the esterification of astaxanthin on the other hand enable the oil globules to maintain the high content of astaxanthin esters.
CHARACTERIZATION OF A SHORT FORM PERIDININ‐CHLOROPHYLL‐PROTEIN (PCP) cDNA AND PROTEIN FROM THE SYMBIOTIC DINOFLAGELLATE SYMBIODINIUM MUSCATINEI (DINOPHYCEAE) FROM THE SEA ANEMONE ANTHOPLEURA ELEGANTISSIMA (CNIDARIA)1
Authors: Weis Virginia M. , Verde E. Alan , Reynolds Wendy S.
Published: March 2003

Peridinin‐chl‐proteins (PCPs) are highly abundant light harvesting pigment proteins unique to the photosynthetic dinoflagellates. Although extensive studies have examined PCP proteins, only four complete pcp nucleotide sequences have been reported to date. PCPs occur in two different forms, a short form with a molecular mass of 14–16 kDa and a long form with a mass of 30–35 kDa, which is thought to have arisen by a gene duplication event. This study describes PCP and its cDNA from Symbiodinium muscatinei (LaJeunesse and Trench), a symbiotic dino‐flagellate resident in the sea anemone Anthopleura elegantissima (Brandt). Two‐dimensional PAGE of S. muscatinei proteins revealed numerous strongly staining spots at a molecular mass of 15.7 and varying pIs. The N‐terminal peptide sequence from one of these spots could be successfully aligned with PCPs from other dinoflagellates, and a complete cDNA sequence was generated by reverse transcriptase PCR, using primers based on the peptide sequence. Northern analyses of RNA revealed a single 1.0‐kb band, suggesting that only the short form of the gene is expressed. The S. muscatinei pcp predicted amino acid sequence displayed a 50%–70% identity with the other known pcp sequences. Interestingly, S. muscatinei PCP was best aligned with the only other short form sequence known, that from Heterocapsa pygmaea, and not with the long form from the congener Symbiodinium sp. from the coral Acropora formosa. Phylogenetic analysis of the five pcp sequences suggests that the PCP gene family is divided into two distinct clades, a short form and a long form, and indicates the existence of two separate genes for the two forms.
PHYLOGENY OF LOBOCHARACIUM (CHLOROPHYCEAE) AND ALLIES: A STUDY OF 18S AND 26S rDNA DATA1
Authors: Buchheim Mark A. , Buchheim Julie A. , Carlson Tracy , Kugrens Paul
Published: March 2003

The phylogenetic affinities of Lobocharacium coloradoense were investigated by analysis of combined 18S and 26S rDNA data. Results from both parsimony and likelihood methods supported a close alliance among Lobocharacium, Characiosiphon, and Characiochloris. These three taxa formed a clade near the base of the “Dunaliella” group within the chlamydomonad lineage. Protosiphon, which exhibits a siphonous habit similar to Characiosiphon and Lobocharacium, was not resolved as a close ally of the latter two taxa. The Lobocharacium alliance was characterized by the presence of an attachment pad associated with the nonmotile vegetative stage and pyrenoids that possess cytoplasmic invaginations. The pyrenoid feature is an ultrastructural trait that has now been observed in five different chlorophycean lineages. The Lobocharacium–Characiosiphon–Characiochloris clade is not predicted by any classifications of green algae. Additional taxon and data sampling need to be completed to resolve inconsistencies between the molecular phylogenetic evidence and at least some of the current family‐level taxa.
MORPHOLOGICAL VARIATION, SPECIES CONCEPTS, AND CLASSIFICATION OF AN UNUSUAL FOSSIL CENTRIC DIATOM (BACILLARIOPHYTA) FROM WESTERN NORTH AMERICA1
Authors: Kociolek J. Patrick , Spaulding Sarah A.
Published: March 2003

The classification system of diatoms (Bacillariophyta) is based almost entirely on the organization and structure of their silica cell walls. We have discovered Miocene freshwater fossils that contain valves of two different orders within the same organism. Within frustules of the genus Ellerbeckia Crawford, a genus of the order Melosirales, are contained frustules of the genus Actinocyclus Ehrenberg, a member of the Coscinodiscales. Based on the abundance of each morphotype, they appear to be able to reproduce themselves. The ability of a single diatom taxon to express this degree of morphological variability is unprecedented. These results suggest species concepts in diatoms may be in need of review and challenge the basis of the classification system for this widely distributed and ecologically important group of organisms.
WAERNIA MIRABILIS GEN. NOV., SP. NOV. (DUMONTIACEAE, GIGARTINALES): A NEW NONCORALLINE CRUSTOSE RED ALGA FROM THE NORTHWESTERN ATLANTIC OCEAN AND ITS RELATIONSHIP TO GAINIA AND BLINKSIA1
Authors: Wilce Robert T. , Maggs Christine A. , Sears James R.
Published: March 2003

Waernia mirabilis Wilce, Maggs et Sears, gen. et sp. nov., is described for an encrusting red alga endemic to the northeastern North Atlantic Ocean. Its perennial thalli form major understory populations that may outcompete Corallinaceae and Hildenbrandiaceae in some habitats. Crustose red algae with isomorphic gametophytes and tetrasporophytes other than Corallinaceae are poorly known; Waernia differs vegetatively and reproductively from any other such algae. Gametangia are similar to those of the monotypic uncalcified crustose genera Blinksia and Gainia endemic to the Antarctic and central coastal California, respectively. Comparison of Waernia with type material of Blinksia californica Abbott & Hollenberg and Gainia mollis Moe shows that it differs from Blinksia in lacking cohesive crusts in which adjacent cells cohere by direct fusions and by its strongly recurved, rather than straight, carpogonial branches. Gainia and Waernia both have strongly recurved carpogonial branches and laxly constructed crusts that lack secondary pit connections. Gainia differs from Waernia in its considerably larger and thicker crusts, non‐nemathecial tetrasporangia, shorter carpogonial branches, and its consistently single gonimoblast initial. We continue to recognize the family Blinksiaceae as a probable member of the Gigartinales with uncertain affinities. Waernia is assigned to the Dumontiaceae (Gigartinales), as its first described isomorphic crustose member. It is also the only genus and one of few algal species endemic to northeastern North America. Waernia either arrived at its present distribution via migration from a Tertiary polar ocean or evolved from an unknown ancestor in a newly formed boreal northwest Atlantic Ocean during post‐Oligocene millennia.