SMITHSONIELLA GEN. NOV., A POSSIBLE EVOLUTIONARY LINK BETWEEN THE MULTICELLULAR AND SIPHONOUS HABITS IN THE ULVOPHYCEAE,CHLOROPHYTA

A low relief, green turf-forming alga of a heterotrichous habit was discovered in the coral reef microcosm, Museum of Natural History, Smithsonian Institution. Erect filaments bore lateral, specialized sporangia and together with basal filaments possessed septal plugs between adjacent cells, grossly similar to the “pit connections” of red algae. Data are presented which: 1) establish the identity of our plant with a plant recently described as Pilinia earleae Gallagher et Humm from the Florida Gulf coast; 2) support our establishment of the new genus Smithsoniella and our transfer of P. earleae to this new taxon. Additional data on pigmentation and cytology are related to the fine structure of other selected green algae to develop and test three hypotheses, viz. Smithsoniella earleae represents either: 1) a symbiotic association between a green and a red alga; 2) an alga which belongs to either the Ulotrichales, Chaetophorales or the Chroolepidales; or 3) an alga representing an evolutionary link between filamentous forms of the Ulvophyceae and members of the coenocytic siphonalean complex (e.g., Codiales or Caulerpales) of the Chlorophyta. Data refute hypotheses 1 and 2 but do lend support to the third hypothesis.     

ALGAL GROWTH OVER THE EPIDERMIS OF SEA URCHIN SPINES

Fosliella farinosa (Lamouroux) Howe, a coralline red alga, was found growing over the epidermis of the spines of the sea urchin, Heterocentrotus trigonarius (Lamarck). This is apparently the first report of the ability of an alga to overcome the resistance to invesion of the external epidermis of a sea urchin.     

Molecular characterization of four genes involved in sulfur metabolism in <Emphasis Type="Italic">Porphyra purpurea</Emphasis> (Roth) C. Agardh

Sulfated polysaccharides (carrageenans and agars) are among the most important products of red algae that are used as food additives as well as in molecular biology research. The quality and value of the product is greatly dependent on the levels and sites of sulfation of the polysaccharides. Little information is currently available on the molecular details of sulfur metabolism in red algae. Considering the economic importance of sulfated polysaccharide, elucidating the molecular details of sulfur metabolism in these organisms could help in future endeavors to improve algal commercial value, e.g., through genetic engineering. A cDNA library from the red alga Porphyra purpurea (Roth) C. Agardh was used to isolate four cDNAs with homology to genes encoding known sulfur assimilation enzymes: sulfate adenyltransferase (ATP sulfurylase), adenosine 5′-phosphosulfate kinase (APSK), sulfite reductase, and cysteine synthase. These cDNAs were characterized with respect to their molecular properties and a cDNA with homology to APSK was used to functionally complement an Escherichia coli auxotroph APSK⁻ mutant. The other cDNAs are being similarly characterized with respect to their ability to produce functional enzymes. Elucidation of the regulation of expression of these genes will aid in future research to determine the biochemical and genetic details of the sulfate assimilation pathway as well as its genetic manipulation in red algae.     

ULTRASTRUCTURE OF VEGETATIVE ORGANIZATION AND CELL DIVISION IN THE UNICELLULAR RED ALGA DIXONIELLA GRISEA GEN. NOV. (RHODOPHYTA) AND A CONSIDERATION OF THE GENUS RHODELLA1

This study suggests that the genus Rhodella be restricted to that set of features currently observed only in Rhodella maculata Evans and Rhodella violacea (Korn-mann) Wehrmeyer, that a new genus Dixoniella be established to accommodate the unicellular red alga, Rhodella grisea (Geitler) Fresnel, Billard, Hindák et Pekár-ková, and that Rhodella cyanea Billard et Fresnel be further studied for probable reclassification. These conclusions are based on ultrastructural comparisons of Dixoniella grisea with published information on the genus Rhodella. The presence of thylakoids in the pyrenoid, a peripheral encircling thylakoid in the chloroplast, a dictyosome/nuclear envelope association, and the lack of a specialized pyrenoid/nucleus association in D. grisea separate this alga from the genus Rhodella. Cell division in D. grisea is not demonstrably different from that in Rhodella, although the unusually well-defined material of the presumptive microtubule organizing center (MTOC) made it possible to follow the development and behavior of the MTOC to a greater degree than in previously studied red algal cells. The surprising amount of conformity in cell division characters between D. grisea and the genus Rhodella prompted a comparison of cell division characteristics in all red algal unicells studied to date. All unicells show a remarkable degree of similarity except for differences in interzonal spindle length, dissimilarities in size of the nucleus-associated organelle (NAO), and the unusual NAO of Porphyridium purpureum (Bory) Drew et Ross.     

EFFECTS OF THE SYMBIOTIC RED ALGA HYPNEOCOLAX STELLARIS ON ITS HOST HYPNEA MUSCIFORMIS (HYPNEACEAE,GIGARTINALES)1

The presence of the “symbiotic” red alga Hypneocolax stellaris Borgesen was found to substantially reduce the growth rate of Hypnea musciformis (Wulfen) Lamouroux. The growth rate of injected field material was 40% less than unifected thalli. Likewise, the growth rate of host thalli infected in the laboratory was reduced 70% compared to uninfected thalli. Neither the quantity nor quality of carrageenan extracted from Hypnea musciformis was directly affected by the presence of Hypneocolax stellaris. In a mariculture system the presence of a symbiotic alga on its host would be expected to reduce the host's growth rate and thereby lower its economic potential.     

Identification of Calmodulin in the Red Alga Susabi Laver (Porphyra yezoensis)

To test whether calmodulin is present in the red alga Susabi laver (Porphyra yezoensis), materials was concentrated from this alga, using hydrophobic chromatography. In this case, 0.25 m (NH₄)₂SO₄ should be added to bind the protein to the column in the presence of 5 mm CaCl₂. Calmodulin is present in the marine red alga, although at a very low concentration.     

BIOGEOGRAPHY AND ECOLOGY OF THE KELP/RED ALGAL SYMBIOSIS

A kelp/red algal symbiosis is described from nature based on extensive collections from the San Juan Islands, Washington. Kelp gametophytes were found as endophytes in the cell walls of seventeen species of red algae in three different kelp communities. Host red algae were mostly filamentous (e.g., Pleonosporium vancouverianum) or polysiphonous (e.g. Polysiphonia paniculata). The kelp gametophytes completed vegetative and reproductive development in the hosts with gametangia formed at the host surface and with sporophytes up to several mm in height being produced while still attached to the host. To date, none of the kelp gametophytes from nature have been identified to genus or species, although the gametophyte of Nereocystis luetkeana is a potential candidate for the symbiosis. Preliminary observations from Nova Scotia and the Isle of Man have not found the association in the Atlantic Ocean. Laboratory studies in Korea successfully reconstructed the symbiosis in the red alga Aglaothamnion oosumiense using zoospores of Undaria pinnatifida but not Laminaria religiosa. Here we outline the development of the symbiosis and discuss the potential adaptive significance of the kelp/red algal interaction.     

Occurrence of the gametophyte of Agarum clathratum (Laminariales, Phaeophyceae) as an endophyte in Orculifilum denticulatum (Gigartinales, Rhodophyceae)

An endophytic filamentous brown alga, growing in the red alga Orculifilum denticulatum Lindstrom, was collected from the north‐east Pacific, near Juneau, Alaska. Within the host tissue, its branched filaments formed a network in the space between the filaments of the host tissues embedded in the host intercellular substances. Cells of the filaments contained many discoid chloroplasts without pyrenoids. Neither microscopic morphological observation nor culturing was sufficient to reveal the specific identity or even the familial affinity of the alga; in contrast, molecular phylogenetic analysis of its rbcL gene and rDNA ITS sequences showed that it was the gametophyte of Agarum clathratum Dumortier (Laminariales). There are few reports of laminarialean gametophytes in nature; this is the first report actually identifying the species of laminarialean gametophyte in a red alga.     

THE RED ALGA GENUS RHODOSPORA (BANGIOPHYCIDAE,RHODOPHYTA): FIRST REPORT FROM NORTH AMERICA1

We recently discovered several populations of the red alga Rhodospora sordida Geitler in samples from seep walls in Tennessee. This species is thought to be an extremely rare alga. It was reported previously only from seep walls in Europe. The last published reports of the alga were made in the mid‐1970s. A culture of the alga was made from one other site in North America (a rock wall in Arkansas) in 1977, but no publication accompanied that find. Since discovering the alga in summer 2004, we found a second population in a seep wall in northeast Ohio. We suspect that this species has a broader distribution than previously thought and has been overlooked or misidentified in past studies.     

PROTEOMICS OF THE RED ALGA,GRACILARIA CHANGII (GRACILARIALES,RHODOPHYTA)1

The application of proteomics in alga research is still quite limited. The present report describes the establishment of the proteome of a red alga of economic importance, Gracilaria changii (Xia et Abbott) Abbott, Zhang et Xia. Initially, four protein extraction methods including direct precipitation by trichloroacetic acid/acetone, direct lysis using urea buffer, Tris buffer, and phenol/chloroform extraction were compared for their suitability to generate G. changii proteins for two‐dimensional gel electrophoresis (2‐DE). The phenol/chloroform protein extraction method gave the best 2‐DE resolution of the proteins. Using these 2‐DE gels and mass spectrometry, several proteins including pigment proteins, metabolic enzymes, and ion transporters were identified. These findings highlight the potential of using proteomic approaches for the investigation of G. changii protein function.     

The Structure and Gene Repertoire of an Ancient Red Algal Plastid Genome

Photosynthetic eukaryotes can, according to features of their chloroplasts, be divided into two major groups: the red and the green lineage of plastid evolution. To extend the knowledge about the evolution of the red lineage we have sequenced and analyzed the chloroplast genome (cp-genome) of Cyanidium caldarium RK1, a unicellular red alga (AF022186). The analysis revealed that this genome shows several unusual structural features, such as a hypothetical hairpin structure in a gene-free region and absence of large repeat units. We provide evidence that this structural organization of the cp-genome of C. caldarium may be that of the most ancient cp-genome so far described. We also compared the cp-genome of C. caldarium to the other known cp-genomes of the red lineage. The cp-genome of C. caldarium cannot be readily aligned with that of Porphyra purpurea, a multicellular red alga, or Guillardia theta due to a displacement of a region of the cp-genome. The phylogenetic tree reveals that the secondary endosymbiosis, through which G. theta evolved, took place after the separation of the ancestors of C. caldarium and P. purpurea. We found several genes unique to the cp-genome of C. caldarium. Five of them seem to be involved in the building of bacterial cell envelopes and may be responsible for the thermotolerance of the chloroplast of this alga. Two additional genes may play a role in stabilizing the photosynthetic machinery against salt stress and detoxification of the chloroplast. Thus, these genes may be unique to the cp-genome of C. caldarium and may be required for the endurance of the extreme living conditions of this alga. Received: 3 June 2000 / Accepted: 18 July 2000     

Astaxanthin Accumulation in the Green Alga Haematococcus pluvialis： Effects of Cultivation Parameters

The green alga, Haematococcus pluvlalis Flotow is used as a source of the ketocarotenoid astaxanthin for application in fish aquaculture, pharmaceutical and cosmetic industries. Ceils of the green alga were induced by the application of different light and starvation conditions to evaluate the effect in astaxanthin accumulate. The conditions used for the Induction were high light intensity （170 μmol·m^-2·s^-1）, iron starvation, sulfur starvation and phosphate starvation. The results show that stresses applied in culture, which interfere with cell division, trigger the accumulation of astaxanthin. Notably, sulfur starvation results in a massive accumulation of this commercially important carotenoid.     

CHLOROPLAST STRUCTURE AND PIGMENT COMPOSITION IN THE RED ALGA GRIFFITHSIA PACIFICA: REGULATION BY LIGHT INTENSITY1

The ratio of accessory phycobiliproteins to chlorophyll a is controlled by light intensity in the marine red alga Griffithsia pacifica. The greatest changes in pigment ratios are observed below 300 ft-c; above 300 ft-c the response approaches saturation. Ultrastructural examination of chloroplasts of plants grown at different intensities reveals that the number of phycobilisomes per unit of photosynthetic thylakoid changes in direct proportion to the pigment ratios and in inverse proportion to the light intensity.     

EPIPHYTES ON CLADOPHORA GLOMERATA IN THE GREAT LAKES AND ST. LAWRENCE SEAWAY WITH PARTICULAR REFERENCE TO THE RED ALGA CHROODACTYLON RAMOSUM (= ASTEROCYTIS SMARGDINA)1

The range of Cladophora glomerata² along the east and north shorelines of the Great Lakes and St. Lawrence Seaway extends form just east of Montreal to Thunder Bay on Lake Superior. However, it does not occur at sites sampled in Georgian Bay, the North Channel or eastern Lake Superior. The dominant epiphytes on Cladophora throughout this range are the blue-green algae, particularly Lyngbya diguetii, L. epiphytica and Chamaesiphon incrustans, which account for 53 to 90% of the cell density. The diatoms Cocconeis pediculus and Rhoicosphenia curvata contribute to much of the remaining density. The red alga Chroodactylon ramosum is a minor component of Cladophora epiphyton but is widespread in Lakes Ontario, Erie and Huron. Filament morphology, cell diameters and lengths of Chroodactylon are quite similar to those of marine forms. In addition, this alga has been reported to be quite tolerant of a wide range of salinities. Chroodactylon has been found in 33 freshwater sites throughout North America and 30 of these are from the Great Lakes or its drainage basin. Therefore, it appears possible that Chroodactylon, like Bangia atropurpurea, has originated in the Great Lakes by a migration from the Atlantic Ocean.     

A “Green” Phosphoribulokinase in Complex Algae with Red Plastids: Evidence for a Single Secondary Endosymbiosis Leading to Haptophytes, Cryptophytes, Heterokonts, and Dinoflagellates

Phosphoribulokinase (PRK) is an essential enzyme of photosynthetic eukaryotes which is active in the plastid-located Calvin cycle and regenerates the substrate for ribulose-bisphosphate carboxylase/oxygenase (Rubisco). Rhodophytes and chlorophytes (red and green algae) recruited their nuclear-encoded PRK from the cyanobacterial ancestor of plastids. The plastids of these organisms can be traced back to a single primary endosymbiosis, whereas, for example, haptophytes, dinoflagellates, and euglenophytes obtained their “complex” plastids through secondary endosymbioses, comprising the engulfment of a unicellular red or green alga by a eukaryotic host cell. We have cloned eight new PRK sequences from complex algae as well as a rhodophyte in order to investigate their evolutionary origin. All available PRK sequences were used for phylogenetic analyses and the significance of alternative topologies was estimated by the approximately unbiased test. Our analyses led to several astonishing findings. First, the close relationship of PRK genes of haptophytes, heterokontophytes, cryptophytes, and dinophytes (complex red lineage) supports a monophyletic origin of their sequences and hence their plastids. Second, based on PRK genes the complex red lineage forms a highly supported assemblage together with chlorophytes and land plants, to the exclusion of the rhodophytes. This green affinity is in striking contrast to the expected red algal origin and our analyses suggest that the PRK gene was acquired once via lateral transfer from a green alga. Third, surprisingly the complex green lineages leading to Bigelowiella and Euglena probably also obtained their PRK genes via lateral gene transfers from a red alga and a complex alga with red plastids, respectively. Electronic Supplementary Material Electronic Supplementary material is available for this article at and accessible for authorised users. [Reviewing Editor: Dr. Patrick Keeling ] The nucleotide sequence data will appear in the DDBJ/EMBL/GenBank International Nucleotide Sequence Database under the following accession numbers. cDNA clones: AY772245 (Pavlova lutheri); AY772246 (Guillardia theta); AY772247 (Lingulodinium polyedrum); AY772248 and AY772249 (Pyrocystis lunula); AY772250 (Euglena gracilis); AY772251 (Chondrus crispus). Genomic clone: AY772252 (Prymnesium parvum). Genomic PCR clone: AY772253 (Bigelowiella natans).     

INCORPORATION OF FRESHWATER RHODOPHYTA INTO THE CASES OF CHIRONOMID LARVAE (CHIRONOMIDAE,DIPTERA) FROM NORTH AMERICA1

Chironomid larvae incorporate pieces of freshwater red algae into their cases from a wide geographic range in North America, extending from southern Canada to central Mexico. The Rhodophyta used in this process represent two orders (Acrochaetiales and Batrachospermales), five genera (Audouinella, Batrachospermum, Lemanea, Paralemanea, and Sirodotia), and 14 species from 21 locations. Three genera from the chironomid subfamily Orthocladiinae make these cases: Cardiocladius, Eukiefferiella, and Orthocladius. The Eukiefferiella claripennis group was the most frequently observed infrageneric taxon using red algae in its cases. The cases were tubular in shape with longitudinally oriented strips of algae held together by silken threads. Some of the cases constructed with Batrachospermum and Sirodotia also had several lateral branches of the alga radiating from the tube.     

THE ANTARCTIC PSYCHROPHILE,CHLAMYDOMONAS RAUDENSIS ETTL (UWO241) (CHLOROPHYCEAE,CHLOROPHYTA), EXHIBITS A LIMITED CAPACITY TO PHOTOACCLIMATE TO RED LIGHT1

The psychrophilic Antarctic alga, Chlamydomonas raudensis Ettl (UWO241), grows under an extreme environment of low temperature and low irradiance of a limited spectral quality (blue‐green). We investigated the ability of C. raudensis to acclimate to long‐term imbalances in excitation caused by light quality through adjustments in photosystem stoichiometry. Log‐phase cultures of C. raudensis and C. reinhardtii grown under white light were shifted to either blue or red light for 12 h. Previously, we reported that C. raudensis lacks the ability to redistribute light energy via the short‐term mechanism of state transitions. However, similar to the model of mesophilic alga, C. reinhardtii, the psychrophile retained the capacity for long‐term adjustment in energy distribution between PSI and PSII by modulating the levels of PSI reaction center polypeptides, PsaA/PsaB, with minimal changes in the content of the PSII polypeptide, D1, in response to changes in light quality. The functional consequences of the modulation in PSI/PSII stoichiometry in the psychrophile were distinct from those observed in C. reinhardtii. Exposure of C. raudensis to red light caused 1) an inhibition of growth and photosynthetic rates, 2) an increased reduction state of the intersystem plastoquinone pool with concomitant increases in nonphotochemical quenching, 3) an uncoupling of the major light‐harvesting complex from the PSII core, and 4) differential thylakoid protein phosphorylation profiles compared with C. reinhardtii. We conclude that the characteristic low levels of PSI relative to PSII set the limit in the capacity of C. raudensis to photoacclimate to an environment enriched in red light.     

CHEMICAL COMPOSITION OF THE CELL WALLS OF THE FRESHWATER RED ALGA LEMANEA ANNULATA (BATRACHOSPERMALES)1

Cell walls of the generic phase of the freshwater red alga Lemanea annulata Kütz were mechanically isolated and chemically characterized. Walls consisted mainly of polysaccharide with lesser quantities of associated protein and lipid. The major wall component was alkali-soluble xylan, comprised mainly of 4-linked β-xylopyranosyl residues and small amounts of 3-O-substituted β-xylopyranosyl residues. Hot water extracts yielded non-sulfated polymers, with 3- or 3,4-linked β-galactosyl residues alternating with 4-linked α-glucuronosyl residues as the predominant structural features. This acid polysaccharide shares many characteristics of the mucilage previously described from the freshwater genus Batrachospermum. Isolated cell walls of L. annulata contained approximately 6% cellulose. Cellobiohydrolase/colloidal gold labelling of cell walls revealed β-4-glycan throughout the fibrillar portion of the wall. Wall protein consisted of at least 17 amino acids, of which threonine and alanine were the most abundant. Polysaccharides of the cell walls of L. annulata differ from those of marine red algae and are similar to those described for other Batrachospermales.     

Simultaneous occurrence of carposporophytes and tetrasporangia in Polysiphonia urceolata

Halosacciocolax lundii sp. nov., a new red alga parasitic on Rhodymenia palmata, is described from Nova Scotia.     

Screening of algal strains for metal removal capabilities

Eight algal species were tested for their ability to remove five toxic metalsduring 30-min exposures to single-metal (1 mg L^-1) solutions at pH7. Efficacy of metal bioremoval varied according to algal species and metal. Al⁺³ was best removed by the thermophilic blue-green alga(cyanobacterium) Mastigocladus laminosus, Hg⁺² and Zn⁺² by the thermophilic and acidophilic red alga Cyanidiumcaldarium, and Cd⁺² by C. caldarium and the green alga Scenedesmus quadricauda. All of these alga/metal combinations resultedin >90% metal removal. However, none of the eight algal speciesremoved more than 10% of Cr⁺⁶. Results indicate that some toxicmetals are more readily removed than others are by algae and that selectionof appropriate strains could potentially enhance bioremoval of specificmetals from wastewater at neutral pH.