bluuebunny/crossref_metadata_2025 huggingface dataset:
SPECIES PHYLOGENY OF COSMARIUM AND STAURASTRUM (DESMIDIACEAE) BASED ON RBC L SEQUENCES
Authors: Lee O.‐M. , McCourt R.M. , Nam M. , Karol K.G.
Published: March 2003

Cosmarium and Staurastrum are the two most diverse genera of placoderm desmids (Family Desmidiaceae), with approximately 1100 and 800 species, respectively. Phylogenetic analysis of relationships of species has been extremely difficult. In a monograph of North American placoderm desmids, Prescott et al. described early phylogenetic work that concluded Staurastrum to be polyphyletic and certainly polymorphic. Likewise, Cosmarium has also been viewed as polyphyletic, and a number of workers have proposed splitting these genera. The classical view of West and West grouped species within each genus into two divisions and 6–8 sections based on wall features and semicell shape. We sequenced rbcL from 18 species of Cosmarium (2 divisions, 7 sections) and 12 species of Staurastrum (2 divisions and 7 sections) and performed a phylogenetic analysis (parsimony, maximum likelihood, bootstrap) using other placoderm desmids and Zygnematales as outgroups. The results exhibit little support for the monophyly of sections or divisions of the two genera. Furthermore, although there is support for the monophyly of clades within each genus, there is also support for a separate clade containing species from both genera.
RELATIVE TOLERANCE OF MAT‐FORMING ALGAE TO COPPER AND ITS IMPLICATIONS
Authors: Lembi C.A.
Published: March 2003

The major method for algae control in the U.S. is the application of copper. Certain groups of phytoplankton, such as the green algae, are known to be more tolerant to copper than groups such as the cyanobacteria. Through experience, commercial applicators suggest that mat‐forming algae also differ in their susceptibility to copper, but to this point, data to support these observations have not been available. Laboratory studies in which unialgal cultures of mat‐forming algae were exposed to a range of copper concentrations show a clear progression in copper tolerance. The EC50 values (concentration of copper in mg Cu L−1 that results in 50% reduction of biomass) were less than 0.003 (Spirogyra, Oedogonium), approximately 0.050 (Hydrodictyon, Pithophora, Rhizoclonium), and greater than 0.200 (Oscillatoria). These data are important to us in the midwest because Oscillatoria is becoming a more frequent component of mat‐forming algae infestations. The Oscillatoria infestations are caused by at least five different species, each of which is very tolerant to copper. Circumstantial evidence suggests that the increasing frequency of this mat‐forming cyanobacterium is due to elimination of more sensitive genera (such as Spirogyra or Rhizoclonium) with heavy copper dosing. In addition to concerns often expressed about copper use, such as buildup in the sediments, toxicity to invertebrates, and possible (although not well verified) resistance of cyanobacteria, another compelling reason to seek alternative approaches to copper is the buildup of copper‐tolerant mat‐forming algae.
PHYTOFLAGELLATES OF THE SALTON SEA: CRYPTOPHYCEAE
Authors: Barlow S.B. , Kugrens P.
Published: March 2003

The species composition of phytoflagellates in the Salton Sea has recently been the subject of intense investigation as part of an analysis of the Salton Sea ecosystem. The Salton Sea, an inland sea occupying 980 km2 in southern California, has become a major stopping point for migratory birds along the Pacific Flyway. The increasing salinity of the sea, currently at 44 gm L−1, and its eutrophic condition (average depth is nine meters, with a high nutrient load contributed by agricultural drainage from the surrounding farmlands) have contributed to a stressed ecosystem. Massive fish kills and bird kills, including such endangered birds as the brown pelican, have become a recurring problem. Although previous investigations have noted the presence of at least two phytoflagellates implicated in fish mortality, little attention has been paid the to the identities of the smaller flagellates observed growing in the sea and their possible contribution to the fish and bird population mortality. Using freshly collected field samples as well as enrichment culture techniques, we report the occurrence of several genera of cryptomonads in the Salton Sea, including representatives from the genera Chroomonas, Hemiselmis, Leucocryptos, Plagioselmis, Storeatula and Teleaulax.
PHYLOGENETIC AND TAXONOMIC REASSESSMENT OF THE DELESSERIACEAE (CERAMIALES, RHODOPHYTA) BASED ON TWO MOLECULAR DATA SETS
Authors: Lin S. M. , Fredericq S. , Hommersand M.
Published: March 2003

The current system of classification of the Delesseriaceae rests largely on Kylin's treatment which encompass the subfamilies Delesserioideae with five ‘Groups’ and Nitophylloideae with six ‘Groups’. In this study we test the Kylin system based on phylogenetic analyses inferred from two molecular data sets and morphological evidence. A total of 145 delesseriacean taxa worldwide were sequenced for chloroplast‐encoded rbcL, and 82 taxa for the nuclear‐encoded large subunit ribosomal RNA gene (LSU). Three large clades are identified in the combined data sets, one of which corresponds to the Delesserioideae, one to a narrowly circumscribed Nitophylloideae, and the third to a new subfamily comprising the remainder of the Nitophylloideae sensu Kylin. Belonging to the Delesserioideae are an expanded Hemineura group that includes Hemineura, Patulophycus, Marionella, Laingia, Botryocarpa and possibly Pseudophycodrys, a Caloglossa group, a Hypoglossum group that includes Hypoglossum, Branchioglossum, Bartoniella, Zellera, Phitymorphora, and Chauviniella, a Delesseria group with Delesseria, Membranoptera and possibly Grinnellia (but not Apoglossum) and most southern hemisphere species of Delesseria which are properly placed in Paraglossum J. Agardh 1898. The revised Nitophylloideae contains Nitophyllum, Valeriemaya, Polyneuropsis, Calonitophyllum and also Martensia and Opephyllum. The unnamed subfamily includes the Phycodrys group with Phycodrys and Polyneura, the Cryptopleura group with species placed in Cryptopleura, Hymenena, Acrosorium and Botryoglossum, the Myriogrammeae with Myriogramme and Haraldiophyllum, and the Schizoserideae with Schizoseris, Neuroglossum, Drachiella, Abroteia, and South American species of Platyclinia. This research promotes the correlation of molecular and morphological phylogenies with biogeographic hypotheses for the family.
SEASONAL GROWTH AND NUTRIENT ECO‐PHYSIOLOGY OF ECKLONIA RADIATA FROM DOUBTFUL SOUND, FIORDLAND, NEW ZEALAND
Authors: Miller S.M. , Hurd C.L. , Wing S.
Published: March 2003

The kelp, Ecklonia radiata, dominates the sublittoral zone within the Doubtful Sound complex. Doubtful Sound is one of a series of fourteen fiords indenting the southwestern coast of the South Island, New Zealand. A feature of these fiords is the freshwater layer that resides atop the salt water, creating a unique marine environment. Mature sporophytes were collected from three sites (two outer sites towards the coastline and one site within the fiord) over a fourteen‐month period (October 1998 to December 1999). Growth rates, measured using the hole punch technique, were greatest in spring at all three sites. The nutrient eco‐physiology of mature E. radiata was investigated by measuring inorganic nitrogen (NO−3 and NH+4) uptake rates at eight concentrations (2–64 μM). Soluble tissue nitrogen (NO−3 and NH+4) and tissue carbon:nitrogen (C:N) ratios were also determined. At all sites, E. radiata showed higher uptake rates for ammonium than for nitrate. In winter, soluble tissue nitrogen was lower at the two outer sites compared to the inner site, while in summer, levels at all sites were similar but had decreased from the winter values. C:N ratios greater than 20 were observed at all sites, increasing in summer to a peak in autumn, suggesting E. radiata may be nitrogen limited, particularly in late summer. Environmental parameters (photon flux density, water temperature, rainfall and wind) were measured, as was sea water velocity around the primary blade of E. radiata, and multivariate correlations used to determine which (if any) environmental parameter exerted greatest influence on eco‐physiological parameters accessed.
PRELIMINARY STUDIES OF SEASONALITY, ECOLOGY, AND SPECIES COMPOSITION OF ULVOID ALGAL BLOOMS IN WASHINGTON STATE
Authors: Nelson T.A.
Published: March 2003

Blooms of green macroalgae can devastate important finfish and shellfish habitats. Ulvaria obscura, a relatively unstudied green alga, is a major contributor to these blooms in the San Juan Islands, Washington State, USA. The biomass and productivity of this and other ulvoid algae were measured seasonally for two years. Experiments comparing the growth rates, responses to desiccation, photoacclimation, and grazer preference of U. obscura and Ulva fenestrata were conducted. Ulvaria blooms tended to occur in the subtidal while Ulva blooms were often intertidal. Both genera bloomed between late June and September. Despite their superficial similarity, Ulvaria and Ulva display markedly different physiological and ecological responses. Ulva was capable of faster growth, had higher rates of photosynthesis, and was more desiccation tolerant than Ulvaria. Ulvaria, however, appears to be more resistant to grazing than Ulva.
IDENTIFICATION OF A GLYCINE DECARBOXYLASE GENE IN THALASSIOSIRA WEISSFLOGII: A PROBE FOR PHOTORESPIRATION IN DIATOMS
Authors: Parker  , Armbrust E.V.
Published: March 2003

Diatoms are responsible for a large percentage of CO2 fixation in the world's oceans. The export of diatom‐fixed carbon from the euphotic zone represents a major sink of CO2 in the global C cycle. Under conditions of high light and high O2/CO2, carbon fixation may be reduced due to photorespiration. The fixation of O2 in photorespiration produces low molecular weight metabolites that cannot be used in the Calvin cycle and are either excreted from the cell or inefficiently salvaged in the photorespiratory pathway. One of the key enzymes of photorespiration is glycine decarboxylase (GDC). We have cloned and sequenced a cDNA corresponding to the gene encoding the T‐protein of GDC from the centric diatom Thalassiosira weissflogii. This cDNA is 1100 bp and its predicted amino acid sequence shows a 45&‘ercnt; identity and a 62% homology with the T‐protein from higher plants. The first 20 amino acids display characteristics of mitochondrial transit peptides, consistent with the localization of GDC in the mitochondria of higher plants. Using competitive RT‐PCR we have demonstrated that transcription of this gene is light‐dependent. Cells maintained at constant growth‐saturating light conditions have much higher levels of T‐protein message than cells kept in the dark for 25 hours. We are currently investigating the effect of other environmental parameters, such as O2 concentration, on T‐protein gene transcription. Ultimately, the goal is to use this gene as a probe for diatom photorespiration in the field. To this end, we are developing degenerate primers and sequencing this gene from other diatom species.
RANGE EXTENSION OF CUTLERIA HANCOCKII (CUTLERIALES; PHAEOPHYTA) TO THE SOUTHWESTERN GULF OF CALIFORNIA, MÉXICO
Authors: Riosmena‐Rodríguez R. , Paul‐Chávez L. , Hinojosa‐Arango G.
Published: March 2003

A range extension of Cutleria hancockii Dawson to the southern portion of the Gulf of California is presented based on collections in Concepción Bay, La Paz Bay and Muertos Bay between March, 1996 and May, 2000. Mature gametangial and sporangial plants were collected in several localities in the low intertidial zone and in subtidial areas. The present records represent a range extension of 500 km for the species with the new southern limit in Punta Perico in Los Muertos Bay. The plants mostly were observed in low intertidial‐shallow subtidial areas associated with Sargassum forest, but also were observed at depths of 30 ft. Based on analysis of the basic morphological and anatomial features of the plants, significant differences within geographic position and depth distribution were noted. Our data suggest that the temperature may be the determining factor in the distribution of this species.
USING RDNA GENES TO UNDERSTAND THE ORIGIN AND EVOLUTION OF SPLICEOSOMAL AND GROUP I INTRONS
Authors: Bhattacharya D. , Lutzoni F. , Reeb V. , Simon D. , Fernandez F. , Friedl T.
Published: March 2003

Ribosomal DNA genes in lichen algae and lichen fungi are astonishingly rich in spliceosomal and group I introns. We use phylogenetic, secondary structure, and biochemical analyses to understand the evolution of these introns. Despite the widespread distribution of spliceosomal introns in nuclear pre‐mRNA genes, their general mechanism of origin remains an open question because few proven cases of recent and pervasive intron origin have been documented. The lichen introns are valuable in this respect because they are undoubtedly of a “recent” origin and limited to the Euascomycetes. Our analyses suggest that rDNA spliceosomal introns have arisen through aberrant reverse‐splicing (in trans) of free pre‐mRNA introns into rRNAs. We propose that the spliceosome itself (and not an external agent; e.g. transposable elements, group II introns) has given rise to the introns. The rDNA introns are found most often between the flanking sequence G (78%) ‐ intron‐G (72%), and their clustered positions on secondary structures suggest that particular rRNA regions are preferred sites (i.e., proto‐splice sites) for insertion. Mapping of intron positions on the newly available tertiary structures show that they are found most often in exposed regions of the ribosomes. This again is consistent with an intron origin through reverse‐splicing. Remarkably, the distribution and phylogenetic relationships of most group I introns in nuclear rDNA genes are also consistent with a reverse‐splicing origin. These data underline the value of lichens as a model system for understanding intron origin and stress the importance of RNA‐level processes in the spread of these sequences in nuclear coding regions.
INTRODUCED MACROALGAE IN THE AUSTRALIAN REGION: CURRENT STATE OF KNOWLEDGE
Authors: Schaffelke B. , Campbell M. L.
Published: March 2003

Introductions of non‐native macroalgae and the subsequent displacement of native species are globally becoming more frequent. The algal genera Undaria, Sargassum, Caulerpa and Codium have been identified as being particularly invasive. An overview on the present knowledge on macroalgal introductions in the Australian region is presented and options for management are discussed, mostly using examples from studies on the introduced Japanese kelp, Undaria pinnatifida. Undaria pinnatifida was first detected in Tasmania, Australia in the early 1980's. Since then, its range has expanded despite eradication efforts. Long distance jumps appear to be the major mode of spread of U. pinnatifida in Tasmania. Studies are underway to distinguish the relative importance of spore dispersal, drift of adult plants and anthropogenic factors in spreading this invasive kelp. Although information on the real impacts of U. pinnatifida and other introduced macroalgae is sparse, the development of management and control strategies is of vital importance to prevent further spread and translocation of these “pest” species.
“SCATTERED CP‐NUCLEOIDS” IN DIATOMS EXPLAINED: BACTERIA ‐ INSIDE THE ENDOPLASMIC RETICULUM ‐ PIERCE THE PLASTIDS OF PINNULARIA
Authors: Schmid A. M.
Published: March 2003

Geitler's (1937) observation on the regular perforation of the chloroplasts of Pinnularia nobilis and the lack of a typical pyrenoid is supported using cytochemistry, and fluorescence & electron microscopy. Chloroplast cavities and channels harbour bacteria, their DNA elicit DAPI‐fluorescence. Previous speculations on the DNA‐positive, achromatic dots in the plastids of several Pinnularia species being “scattered chloroplast nucleoids,” and the consequent separation of diatom plastids in “primitive” and “advanced” types, are thus refuted. Bacteria are rod‐shaped and as suggested by their TEM‐profiles gram‐negative proteobacteria. They occur inside the endoplasmic reticulum throughout the cell, in interphase prevailingly in the space between the periplastidial membrane (PPM) and the CER membrane. Clusters of bacteria inside ER‐cisternae near the nucleus in preprophase, and near the new plasmalemma after cleavage, indicates a cell‐cycle dependent translocation within the diatom. Cavities in the plastids seem to be created by a combination of mechanical and chemical forces, in the sequence: alignment, attachment, deformation and lysis, initially without an obvious disruption of the PPM and the chloroplast‐envelope. Our future goal is to identify the bacteria and their metabolic function in the hereditary association with the plastids in Pinnularia. Their intracellular, but extraplasmatic, location may reflect an ancestral constellation, and the apparent worldwide distribution may substantiate this view.
A RE‐EVALUATION OF CORALLINE RED ALGAL TAXONOMY USING ULTRA‐STRUCTURAL INFORMATION
Authors: Broadwater S. , Scott J.
Published: March 2003

Two competing subfamily classification schemes for the red algal family Corallinaceae are in general agreement with respect to the taxonomic value of cell connection type (cell fusions versus secondary pit connections), but differ over the relative weight given to the character of genicular presence/absence. Consequently, Corallinoideae, Melobesioideae and Metagoniolithoideae are recognized as distinct subfamilies. One scheme subsumes the geniculate Amphiroideae into the nongeniculate Lithophylloideae (based on the common presence of secondary pit connections) and the nongeniculate Mastophoroideae into the geniculate Corallinoideae (based on the common presence of cell fusions); the other maintains these subfamilies as four separate lineages. Small subunit rRNA gene sequence data confirms the integrity of Corallinoideae and Melobesioideae and fully supports a revised classification subsuming Amphiroideae into Lithophylloideae. Surprisingly, Mastophoroideae and Metagoniolithoideae (cell fusions) have a closer affinity to the emended Lithophylloideae (secondary pit connections) than with Corallinoideae (cell fusions). These preliminary results cast doubt on the value of using cell connections as a primal character. From ultrastructural investigations of 28 corallinoidean genera, including seven mastophoroidean genera and two lithophylloidian genera, it appears that the presence/absence of an electron‐ dense material (EDM) surrounding nuclei during sporogenesis is a more reliable indicator of subfamily affiliation than cellular connections. Our findings support the revised classification of Lithophylloideae and suggests closer affinity to Lithophylloideae (secondary pit connections, no EDM) than to Corallinoideae (cell fusions, EDM). However, EDM data indicates that Mastophoroideae may be polyphyletic as three genera have EDM and four do not.
FUCUS VANADIUM PEROXIDASE: MINIMUM CATALYTIC DOMAIN SIZE RETAINING PEROXIDASE ACTIVITY
Authors: Vreeland V.J. , Ly L.S. , Riebe J. L. , Sabatier C. , McCoy I. S.
Published: March 2003

Vanadium peroxidase catalyzes the extracellular assembly of Fucus zygote cell surface adhesive (Vreeland & Epstein 1996, Modern Meth. Plant Anal. 17, 95–116). Our goal is to identify the catalytic, self‐associating and wall targeting functional domains of algal vanadium peroxidase to understand its role in algal propagule adhesion. As a first step, we truncated our recombinant Fucus vanadium peroxidase (GenBank AF053411) for catalytic domain identification. Recombinant constructs were prepared which reduced the C‐terminal catalytic domain at either or both N‐ and C‐terminal ends. Recombinant proteins were expressed in E. coli, refolded from cytoplasm and inclusion bodies and tested for vanadium‐specific o‐dianisidine peroxidase activity. Preliminary results demonstrated peroxidase activity when the 40 kDa catalytic domain was truncated on both ends to 24 kDa. Further terminal and internal truncation is needed to fully define the minimal catalytic unit, which could be as small as 15–20 kDa within the 73 kDa monomer. The very small catalytic unit in Fucus vanadium peroxidase is not unexpected considering the rigid bundled helical vanadate frame in the Curvularia fungal vanadium peroxidase (Macedo‐Ribeiro et al. 1999, J. Biol. Inorg. Chem. 4, 209–219). We conclude that interactions between the N‐terminal noncatalytic domain and the C‐terminal catalytic domain, found in the crystalline Ascophyllum enzyme (Weyland et al. 1999, J. Mol. Biol. 293, 595–611), are unnecessary for peroxidase activity. Other conserved amino acids in the C‐terminal half of Fucus vanadium peroxidase, peripheral to the helical core, could participate in protein surface functions such self‐association and wall targeting.
A REASSESSMENT OF ITS/5.8S DNA SEQUENCE VARIATION AND PHYLOGENETIC SIGNAL IN THE SYNUROPHYCEAE
Authors: Wee J. L.
Published: March 2003

Previously, DNA sequences were determined for the entire ITS/5.8S region by direct sequencing of PCR amplification products. 28 sequences were obtained from 12 species of Synurophyceae, including Tessellaria volvocina, Chrysodidymus synuroideus, six species of Synura and four species of Mallomonas. Sequences also were determined from multiple strains of some species, including 15 strains of Synura petersenii. The length of these sequences varied from 495–598 bp. The large amount of ITS/5.8S length variation made initial attempts in determining reliable sequence alignment difficult and precluded their use in phylogenetic analyses of the class. Subsequently, the approach of Bogler & Simpson (1996) was investigated where reiterative, computer assisted alignments were generated and the quality of the alignment was evaluated by homoplasy index and consistency index values. However, these alignments also were equivocal. ITS/5.8S sequences sorted the 15 S. petersenii strains into two well supported ITS lineages. One ITS type included ten isolates from North America while isolates from the second ITS type included one each from Germany and Australia and three from North America. Results are presented here where the sequences from the 15 S. petersenii isolates were used to characterize ITS‐1 and ITS‐2 RNA transcript secondary structure. Next, this information was expanded to include ITS/5.8S sequences from the other taxa in the class. Finally, the characteristics of ITS 1 and ITS 2 RNA transcript secondary structure were used as a guide to align all of the ITS/5.8S sequences from the Synurophyceae in a final phylogenetic analysis.
PORPHYRA SUBORBICULATA, PORPHYRA CAROLINENSIS AND PORPHYRA LILLIPUTIANA ‐ THREE NAMES FOR ONE SMALL PORPHYRA
Authors: Broom J.E. , Nelson W.A. , Jones W.A. , Yarish C. , Aguilar Rosas R. , Aguilar Rosas L.E.
Published: March 2003

The genus Porphyra is ancient, successful, and morphologically simple. Its members provide a particular challenge to systematists who must decide whether shared features are a result of homoplasy, or reflect recent common ancestry. Three species of diminutive Porphyra with widespread geographic origins share many common morphological features: P suborbiculata Kjellm. has been reported from the west Pacific and Indian Oceans, P. carolinensis Coll et J. Cox from the west Atlantic, and P lilliputiana W. A. Nelson, G. A.Knight et M. W. Hawkes from New Zealand. Comparison of 18S rDNA sequence data from small Porphyra thalli from Mexico, Japan, New Zealand, Australia and Connecticut indicate that these three taxa in fact belong to one cosmopolitan species, which is distributed over three oceans and two hemispheres. Analysis of sequence data from introns present in the 18S rDNA and from the ITS region suggest that this distribution may be linked to human activity, and raises the question of to which geographic locality this entity is truly endemic?
MECHANISMS CONTROLLING NUCLEAR MIGRATION ALONG THE TRICHOGYNE IN THE RED ALGA, BOSTRYCHIA MORITZIANA (RHODOMELACEAE, RHODOPHYTA)
Authors: Wilson S. M. , Pickett‐Heaps J.D. , West J.A.
Published: March 2003

Sexual reproduction in red algae has been studied for over a century primarily for taxonomic purposes. Despite this interest, only recently have the critical events of fertilisation been revealed. Time‐lapse video microscopy techniques have been used to document the stages in the fertilization process within Bostrychia moritziana. Once plasmogamy between a trichogyne and spermatium is achieved, two differentiated male nuclei may enter the trichogyne. One of the two migrates to the carpogonium while the other travels in the opposite direction towards the trichogyne tip and plays no further role in fertilisation. The precise mechanism governing this bidirectional movement of male nuclei is unknown, but the cytoskeleton is believed to be involved. Fluorescent staining and confocal microscopy shows an extensive arrangement of actin filaments in spermatia and along trichogynes yet microtubules are only evident in dividing spermatia. Actin filaments appear to be involved in plasmogamy and ensheath male nuclei as they migrate from the spermatium and as they travel along the trichogyne in either direction. Drug‐inhibition studies and UV‐microbeam irradiation indicate nuclear migration along trichogynes is actin/myosin dependent
MOLECULAR AND GENETIC ANALYSIS OF A RETROGRADE SIGNALING PATHWAY FROM THE PLASTID TO THE NUCLEUS
Authors: Chory J. , Larkin R. , Surpin M. , Mochizuki N. , Brusslan J.
Published: March 2003

Chloroplast development requires coordinate nuclear and chloroplast gene expression. A putative signal from the chloroplast couples the transcription of certain nuclear genes encoding photosynthesis‐related proteins with chloroplast function. We have identified five Arabidopsis nuclear genes (GUN1‐GUN5) necessary for coupling the expression of some nuclear genes to the functional state of the chloroplast. Homozygous recessive gun mutations allow nuclear gene expression in the absence of chloroplast development. GUN1 mutants have no visible phenotype in white light, but GUN1 mutations interfere with the switch from heterotrophic to photosynthetic growth in young seedlings. GUN2‐5 are pale. Double mutant studies suggest that gun1 affects a separate pathway from GUN2, 3, 4, and 5. GUN2 and GUN3 are allelic to the known photomorphogenetic mutants, hy1 and hy2, involved in phytochromobilin biosynthesis downstream from heme. GUN5 encodes the ChlH subunit of Mg‐chelatase, and GUN4 encodes a novel chloroplast protein that is essential for chlorophyll accumulation. GUN4 does not appear to be required for the synthesis of protochlorophyllide from 5‐aminolevulinic acid, which suggests that GUN4 might be required for the early steps and/or the late steps of chlorophyll synthesis or another process that is required for chlorophyll accumulation. Our data suggest that certain perturbations of the tetrapyrrole biosynthetic pathway generate a signal from chloroplasts that causes transcriptional repression of nuclear genes encoding plastid‐localized proteins. The precise nature of this signal and the mechanism by which this signal is transduced to the nucleus is under investigation.
PHYLOGENETIC RELATIONSHIP OF COLEOCHAETE AND CHAETO‐SPHAERIDIUM (COLEOCHAETALES) BASED ON THE CHLOROPLAST GENES RBCL AND ATPB
Authors: Cimino  , Karol K. G. , Lewandowski J.D. , Delwiche C.F.
Published: March 2003

The freshwater green algal genera Coleochaete and Chaetosphaeridium form the order Coleochaetales sensu Mattox and Stewart (Charophyceae). To test the monophyly of this order, a data set was compiled consisting of the chloroplast genes rbcL and atpB from nine species of Coleochaete, six strains of Chaetosphaeridium, and other representative green algae and embryophytes. Phylogenetic analyses of these data indicate that Coleochaete and Chaetosphaeridium form a monophyletic group that diverged late in basal streptophyte evolution. By contrast, published analyses of nuclear encoded small subunit ribosomal DNA (rDNA) data for similar taxa do not support a monophyletic Coleochaetales. These analyses suggest Chaetosphaeridium is an early branching lineage within Streptophyta and/or that Chaetosphaeridium forms a lineage with the unicellular flagellate Mesostigma (Mesostigmatophyceae). A close relationship of Chaetosphaeridium and Mesostigma is not supported by the rbcL and atpB data. Reexamination of morphological characters suggests a monophyletic Coleochaetales is supported by several characters that include branching filamentous habit, unicellular apical growth, sheathed hairs, and rotating plastids.
TUBE SIZE COMPARISON AND AUTOMATED GROWTH MEASUREMENT IN A TUBULAR REACTOR USING SPIRULINA PLANTENSIS
Authors: Coin  , Bagherpour S. , Gellenbeck K.W.
Published: March 2003

A tubular photobioreactor for outdoor cultivation of Spirulina platensis was successfully operated for the last two years. The reactor was made of transparent 2.4‐cm diameter tubes with a total length of approximately 101‐m and a volume of 124‐liter. Flow was induced using an airlift pumping system. To optimize the system further, a larger tube diameter was also tested. Preliminary results have suggested that a larger tube diameter might provide increased output with reduced surface area requirements. Results of experiments comparing the productivity of the same culture volume in tubes of 2.4 cm and 5.0 cm will be presented which show a small decrease in productivity by volume, but a large increase in areal productivity. This suggests that the larger tube diameter would be an appropriate choice for larger scale systems. Additionally, data will be presented demonstrating the effectiveness of an on‐line surface scatter turbidimeter for accurate measurement of Spirulina density when correlated to manual dry weight measurements.
GROWTH AND ULTRASTRUCTURAL CHANGES IN DICTYOSPHAERIUM PULCHELLUM EXPOSED TO COPPER (CHLOROCOCCALES, CHLOROPHYCEAE)
Authors: De La Peña G. , Andrade L.R. , Amado Filho G. M. , Rodríguez M.C.
Published: March 2003

In an assay addressing the toxicity of copper to Dictyosphaerium pulchellum, a 48 hours' exposure of axenic cultures of the alga to metal concentrations ranging from 0 to 300 mg L−1 caused a significant decrease in the growth rate and cell chlorophyll content. Extracellular mucilage remotion by controlled sonication before exposure to copper emphasized chlorophyll content reduction, but not cellular density diminution. Because mucilage acts as a cation interchanger, these results suggested that, during at least the first 48 hours, division rates might be affected by lower Cu+2 concentrations than chlorophyll content. Ultrastructural observations showed that the normal organization of the chloroplasts was altered; they presented dilated lamellae, irregularly arranged with practically no stacking. Copper precipitates were mainly observed outside the plasmalemma or within the extracellular mucilage. Electron probe microanalysis confirmed these observations, showing only minor precipitates inside the cells.
PHYLOGENETIC SELECTION OF A RESOURCE: A NEW USE FOR CLADISTICS
Authors: Dreckmann K. M. , De Lara‐Isassi G. , Alvarez‐Hernández S.
Published: March 2003

A phylogenetic model for the selection of commercial resources using the cladistic method is proposed. The group selected as an example was the marine agarophyte red algal genus Gracilaria Greville. We suggest the use of the cladistic principle of evolutionary transformational series in order to test the quality of agars instead of the assay‐herror traditional method that consumes time and budget. If we asume that the “good quality of agar” in extant taxa is a sinapomorphic character (but not a reliable taxonomic one), then taxa included in the same monophiletic clade in which the species with “good quality of agar” are, has a high evolutionary posibility to share that character. In order to do this we have to incorporate to the set of available specific characters, those of the taxa actually used as a agar source but not present in the area under scope. A complete set of the basic cladistic data required for run the most popular program currently in use (PAUP) are provided. We applied the model to the Mexican Atlantic species and found that, using Gracilaria chilensis and G. cornea as “indicator taxa,” and found Mexican populations of G. crassissima, G. caudata, G. cervicornis and Gracilariopsis lemaneiformis are candidates for a study of yield and agar properties.
IN VIVO CHARACTERIZATION OF THE DIATOM MULTIPARTATE PLASTID TARGETING SIGNAL
Authors: Apt K.E. , Zaslavskaia L. , Lippmeier J.C. , Lang M. , Grossman A.R. , Kroth P. G.
Published: March 2003

Diatoms and related algae have plastids that are surrounded by four membranes. The outer two membranes are continuous with the endoplasmic reticulum and the inner two membranes are analogous to the plastid envelope membranes of higher plants and green algae. Thus the plastids are completely compartmentalized within the ER membranes. The targeting presequences for nuclear‐encoded plastid proteins have two recognizable domains. The first domain is a classic signal sequence, which presumably targets the proteins to the endoplasmic reticulum. The second domain has characteristics of a transit peptide, which targets proteins to the plastids of higher plants. To characterize these targeting domains, the presequence from the nuclear‐encoded plastid protein AtpC was utilized. A series of deletions of this presequence were fused to Green Fluorescent Protein (GFP) and transformed into cells of the diatom, Phaeodactylum tricornutum. The intracelluar localization of GFP was visualized by fluorescence microscopy. This work demonstrates that the first domain of the presequence is responsible for targeting proteins to the ER lumen and is the essential first step in the plastid protein import process. The second domain is responsible to directing proteins from the ER and through the plastid envelope and only a short portion of the transit peptide‐like domain is necessary to complete this second processing step. In vivo data generated from this study in a fully homologous transformation system has confirmed Gibbs' hypothesis regarding a multistep import process for plastid proteins in chromophytic algae.
PHYLOGENETIC AND BIOGEOGRAPHIC AFFINITIES OF THE HALYMENIALES AND RHODYMENIALES (RHODOPHYTA) FROM THE GULF OF MEXICO
Authors: Gavio B. , Fredericq S. , Mendoza‐Gonzalez C. , Mateo‐Cid L. , Aguilar‐Rosas L. E. , Aguilar‐Rosas R.
Published: March 2003

Generic and species concepts within the red algal assemblages Halymeniales and Rhodymeniales are discussed for taxa inhabiting the western Gulf of Mexico. Two principal biogeographic assemblages occur: an off‐shore deep‐water group (including Coelarthrum cliftonii, Halymenia spp., Botryocladia spp., Gloiocladia) representing remnants of a Tethyan distribution, and a near‐shore intertidal flora (comprising Rhodymenia, Grateloupia and Prionitis) which instead reveals biogeographic affinities with the Carolinian Province. These two distinct marine floras will be contrasted phylogenetically based on DNA sequence analysis inferred from chloroplast‐encoded rbcL. The generic descriptions of Grateloupia and Prionitis are in need of taxonomic revision based on a survey of species from Caribbean and Pacific Mexico.
FUNCTIONAL BINDING OF DIATOM PIGMENTS TO A RHODOPHYTE LIGHT HARVESTING POLYPEPTIDE
Authors: Grabowski B. , Cunningham F.X. , Gantt E.
Published: March 2003

A close relationship of light harvesting polypeptides (LHC) of rhodophytes, chromophytes and chlorophytes is inferred from the amino acid sequence similarity in three transmembrane helices, and from the conservation of 8 putative chlorophyll (Chl)‐binding sites (Durnford et al. 1999, J. Mol. Evol. 48:59). Differences in Chl and carotenoid pigments have been a major classification feature. Thus, it was of interest to ascertain whether pigments from a diatom (Thallasiosira fluviatilis) could be functionally inserted into a red algal (Porphyridium cruentum) polypeptide. A recombinant polypeptide, LHCaR1, was reconstituted with pigment extracts from the diatom (Chls a and c, fucoxanthin, diadinoxanthin and β‐carotene). The pigments were found attached to protein upon separation on sucrose gradients, and on non‐denaturing gels. Absorption and fluorescence excitation spectra revealed individual peaks corresponding to the absorption maxima of Chl a at 438/672 nm; Chl c at 463/638 nm; and fucoxanthin at 493/540 nm. Fluorescence emission and CD spectra showed functional binding and suitable orientation for energy transfer from Chl c and carotenoids to Chl a. The LHCaR1 successfully folded in the presence of the heterologous pigments and bound 7 Chl a, 1 Chl c, 8 fucoxanthin, and 1.9 diadinoxanthin per polypeptide. By comparison, this polypeptide with P. cruentum pigments binds 8 Chl a, and 4 zeaxanthins, thus revealing its capability of functionally binding 8 Chls with variations in carotenoid numbers. Such a trait may have favored the diversification of a large family of LHCs and the successful radiation of photosynthetic eukaryotes into different light environments.
GRACILARIA FROM THE GULF OF MEXICO, WITH SPECIAL EMPHASIS ON GRACILARIA TIKVAHIAE BASED ON TWO MOLECULAR DATASETS
Authors: Gurgel C.F. , Fredericq S. , Norris J.N.
Published: March 2003

Despite a recent body of literature, the species of Gracilaria recognized for the Gulf of Mexico are still incompletely characterized, misidentified, and species limits not well defined due to huge morphological plasticity and overlapping habits. To better characterize these taxa and evaluate their taxonomic relationships, we provide a chloroplast‐encoded rbcL phylogeny encompassing primarily Gulf, western Atlantic, and Caribbean species. Our results indicate the need to resurrect older, validly published names currently placed in synonymy under other species of Gracilaria, and to describe new species. For Gracilaria tikvahia, in particular, a combination of DNA sequences [rbcL, and internal transcribed spacer regions (ITS) of nuclear ribosomal DNA] from specimens collected across a wide biogeographic area (Nova Scotia, Canada, to Las Coloradas, Yucatan Peninsula) successfully promotes the integration and correlation of molecular phylogenies and morphology with biogeographic hypotheses.
PHYLOGEOGRAPHY AND WITHIN‐STREAM GENETIC VARIATION OF BATRACHOSPERMUM HELMENTOSUM (RHODOPHYTA) USING INTER‐SIMPLE SEQUENCE REPEATS
Authors: Hall M. M. , Vis M. L.
Published: March 2003

A relatively new molecular marker technique, inter‐simple sequence repeats (ISSR), was used to assess the within‐stream reach genetic variation and phylogeography of the freshwater red alga, Batrachospermum helmentosum. The within‐stream reach study was undertaken in Southeastern Ohio, where 58 individuals were collected from an approximately 200 m stream length. Individuals appeared to be congregated into three distinct areas, with no plants between areas. Using three primers, 100 polymorphic bands were scored. Although it was hypothesized that genetic variation would reflect physical distance, the results showed six distinct genetic groupings, some of which consisted of physically distant individuals. Overall, genetic diversity was greater among individuals than between geographic and genetic groups. To investigate phylogeography, 11 stream reaches (3 from Ohio and one each from Connecticut, Massachusetts, Rhode Island, North Carolina, Tennessee, Indiana, Michigan and Louisiana) were sampled throughout the alga's known distribution in North America. Approximately 15 individuals were collected per stream for ISSR analysis. Five primers, yielding 243 polymorphic bands, were used to examine variation among all individuals. Neighbor‐joining trees generated from the Dice, Jaccard and Excoffier coefficients showed that individuals from the same stream formed a clade. Among streams there was no distinct correlation between geographic distance and genetic similarity. Genetic groupings varied slightly among distance coefficients employed. Michigan and Tennessee, Connecticut and Rhode Island, and Indiana and Massachusetts streams consistently showed the same relationship, but the relationships among the three Ohio streams and Louisiana stream were variably related to each other.
ALGAL‐RELATED TASTES AND ODORS IN PHOENIX WATER SUPPLY: PRELIMINARY REPORT
Authors: Hu Q. , Dempster T. , Lowry D. , Sommerfeld M. , Westerhoff P. , Bruce D. , Nguyen M. L. , Baker L.
Published: March 2003

Frequent episodes of algal‐related tastes and odors (T & O) in drinking waters in metropolitan Phoenix, Arizona prompted initiation of a three‐year project in July 1999 to investigate the occurrence of T & O metabolites and to develop a comprehensive management strategy to reduce the problems in drinking water supplies in arid environments. Two metabolites, 2‐methylisoborneol (MIB) and geosmin, have been identified as compounds responsible for the earthy‐musty tastes and odors in water supplies. Both were detected in the water supply system, including source rivers, reservoirs, canal delivery system and water treatment plants. Higher concentrations of MIB and geosmin occurred in distribution canals than in the upstream reservoirs indicating that significant production of the T & O compounds occurs within the canal system. A baseline‐monitoring program has been established for the complex water supply system, with special emphasis on the canal system. Efforts are underway to investigate possible correlations between physical/chemical parameters, algal composition and biomass, with the occurrence of MIB and geosmin. In addition, several physical and chemical treatments are planned for the canal system to reduce algal growth and related MIB and geosmin concentrations.
NUTRIENT LIMITATION OF PHYTOPLANKTON IN A SEASONALLY OPEN BAR‐BUILT ESTUARY: WILSON INLET, WESTERN AUSTRALIA
Authors: Twomey Luke , Thompson Peter
Published: March 2003

The potential for nutrient limitation to affect the phytoplankton community was assessed from 1997 to 1998 in Wilson Inlet, Western Australia. Samples of the endemic phytoplankton community were assayed by giving them nutrient mixes deficient in one of the following: nitrogen, phosphate, silicate, iron, trace metals, or vitamins. When ranked from those treatments with the most potential to limit phytoplankton biomass to those with less potential, the bioassay results suggested that N>P>>Si>Fe, and trace metals and vitamins were never potentially limiting. In summer and autumn, the bioassay data suggested that nitrogen and phosphorus were the nutrients with greatest potential to constrain phytoplankton biomass. Though the concentrations of soluble nutrients were high in winter, bioassays indicated that the phytoplankton community was potentially nutrient limited. Physical conditions such as high flow rate, greater turbidity, lower temperature, and greater light attenuation contributed to lower phytoplankton growth rates during winter. The bioassay data indicated that the phytoplankton biomass was least likely to be constrained by dissolved inorganic nutrients in spring than any other time of the year. In spring the endemic phytoplankton community responded to salinity‐stratification induced sediment‐nutrient release with a marked increase of biomass. Nitrogen was the nutrient with greatest potential to limit the phytoplankton biomass during spring. The bioassay data conflicted with the dissolved inorganic nitrogen to phosphorus molar ratios, which suggested that P was more likely to limit the phytoplankton biomass during spring. The discrepancy between the two data sets was probably caused by inaccuracies in measuring the concentration of dissolved inorganic phosphorus in spring. Therefore, the results from the current study suggest that the Redfield paradigm, based on the ratio of dissolved inorganic nutrient concentration, provided an inadequate description of phytoplankton nutrient limitation in Wilson Inlet.
POLARELLA GLACIALIS, GEN. NOV., SP. NOV. (DINOPHYCEAE): SUESSIACEAE ARE STILL ALIVE!
Authors: Montresor Marina , Procaccini Gabriele , Stoecker Diane K.
Published: March 2003

The culture CCMP 1383, obtained from sea‐ice brine collected in McMurdo Sound (Ross Sea, Antarctica), is a small gymnodinioid dinoflagellate. This species is very abundant in the upper land‐fast sea ice, where it can both grow and overwinter as a spiny encysted stage. The motile vegetative stage and the cyst produced in the culture were studied by scanning electron microscopy (SEM) and transmission electron micrscopy (TEM). The amphiesma of the vegetative cells is constituted by thin vesicles that are organized into nine latitudinal series of plates: three in the epitheca, two in the cingulum, and four in the hypotheca. The same tabulation is reflected in the cyst wall by acicular processes arising from the center of paraplates, with the exception of the paracingulum, in which acicular processess are absent. On the basis of the peculiar plate pattern of this dinoflagellate, we establish the new genus Polarella and the new species Polarella glacialis (family Suessiaceae, order Suessiales). This species has a remarkable similarity with fossil Suessiaceae cysts dating back to the Triassic and Jurassic and represents, up to now, the only extant member of the subfamily Suessiaceae. Phylogenetic analysis based on the small‐subunit ribosomal RNA gene confirmed the placement of this species in the order Suessiales and its close relationship with the genus Symbiodinium Freudenthal.
BIOCHEMICAL TAXONOMY AND MOLECULAR PHYLOGENY OF THE GENUS CHLORELLA SENSU LATO (CHLOROPHYTA)
Authors: Huss Volker A. R. , Frank Carola , Hartmann Elke C. , Hirmer Monika , Kloboucek Annette , Seidel Barbara M. , Wenzeler Petra , Kessler Erich
Published: March 2003

A multimethod approach was used to characterize unicellular green algae that were traditionally assigned to the genus Chlorella Beijerinck and to resolve their phylogenetic relationships within the Chlorophyta. Biochemical, physiological, and ultrastructural characters, together with molecular data such as DNA base composition and DNA hybridization values, were compared with a molecular phylogeny based on complete 18S rRNA sequences. Our results show that Chlorella taxa are dispersed over two classes of chlorophytes, the Trebouxiophyceae and the Chlorophyceae. We propose that only four species should be kept in the genus Chlorella (Chlorophyta, Trebouxiophyceae): C. vulgaris Beijerinck, C. lobophora Andreyeva, C. sorokiniana Shih. et Krauss, and C. kessleri Fott et Nováková. Common characteristics of these taxa are glucosamine as a dominant cell wall component and the presence of a double thylakoid bisecting the pyrenoid matrix. Norspermine, norspermidine, and secondary carotenoids are never produced. Other “Chlorella” species belong to different taxa within the Trebouxiophyceae (“C.” protothecoides=Auxenochlorella protothecoides[Krüger] Kalina et Punčochářová, “C.” ellipsoidea, “C.” mirabilis, “C.” saccharophila, and “C.” luteoviridis) and Chlorophyceae (“C.” zofingiensis and “C.” homosphaera=Mychonastes homosphaera Kalina et Punčochářová). The latter taxa can easily be recognized by the production of secondary carotenoids under nitrogen‐deficient conditions.