Conchospore production and seasonal occurrence of some Porphyra species (Bangiales,Rhodophyta) in Washington State

The leafy thalli of species of the marine red algal genus Porphyra grow rapidly but persist for a relatively short time on rocky intertidal or subtidal substrata or as epiphytes on other marine plants. In most species, the large, short-lived leafy thalli alternate with small, presumably perennial, filamentous conchocelis plants. Depending on the species of northeastern Pacific Porphyra, photoperiod and temperature are important regulators of conchospore formation and release. Data from laboratory studies of conchospore formation and release in five Washington species of Porphyra (P. abottae, P. nereocystis, P. perforata, P. pseudolanceolata and P. torta) indicate that conchospores are most likely to be released at a time that precedes the appearance of the leafy thalli in the field.     

Distribution and population dynamics of Porphyra (Bangiales, Rhodophyta) in the southern Western Cape, South Africa

Although Porphyra is commercially farmed in many countries, in South Africa only small harvests of wild populations for sale as nori have been carried out. The discovery that Porphyra improves growth of South African abalone (Haliotis midae) farmed inland-based tanks has led to increased pressure to harvest wild populations. This paper reports on a survey of the distribution and seasonality of Porphyra in the southern Western Cape. Porphyrawas present at all sites surveyed, and showed considerable temporal variation. A significant amount of the Porphyra present is in reserves and therefore protected from harvesting. Close rexamination of one site revealed seasonal populations of Porphyra that occupied different niches dependent on season. Recruitment peaked in spring and autumn, leading to dense summer and winter populations. Summer populations generally grew lower in the eulittoral than winter populations. No pattern in the mortality of larger thalli wasde tected, though sporeling mortality was high following recruitment peaks. Although it seems that most sites in the southern Western Cape are suitable for harvesting, the taxonomy of the genus in the region urgently needs revision if populations are to be appropriately managed. This revised version was published online in August 2006 with corrections to the Cover Date.     

Forecasting infections of the red rot disease on Porphyra yezoensis Ueda (Rhodophyta) cultivation farms

Pythium porphyrae is a fungal pathogen responsible for red rot disease of the seaweed Porphyra (Rhodophyta). Infection forecasts of Porphyra by P. porphyrae were estimated from the epidemiological observations of Porphyra thalli and numbers of zoospore of P. porphyrae in laboratory and cultivation areas. Four features of forecasting infections were determined by relating zoospore concentrations to the incidence of thallus infection; infection (in more than 1000 zoospores L⁻¹), microscopic infection [less than 2 mm in diameter of lesion (in from 2000 to 3000 zoospores L⁻¹)], macroscopic infection [more than 2 mm in diameter of lesion (in from 3000 to 4000 zoospores L⁻¹), and thallus disintegration (in more than 4000 zoospores L⁻¹). High zoospore concentrations led to more infection. The tendency that zoospore concentration of P. porphyrae increased with the rate of infection of Porphyra thalli was generally observed in forecasting infections in both the laboratory and in cultivation areas. Based on the Porphyra cultivation areas, the accuracy and consistency of forecasting infections suggest that this method could be employed to manage and control red rot disease.     

Serological detection of red rot disease initiation stages of microbial pathogen, Pythium porphyrae (Oomycota) on Porphyra yezoensis

Pythium porphyrae (Oomycota), a pathogen causing red rot diseasein Porphyra spp., can at present only be detected when colonizationof the host thallus has already occurred and so it is often too late to takeappropriate disease control measures. The paper presents an account of an effective methdology for early detection of the disease. Since Py.porphyrae zoospores are the primary means of pathogen dispersal,polyclonal antibodies (Pabs) were raised against the surface components ofzoospores and encysted zoospores. Using these Pabs the disease initiationstages of the Pythium porphyrae were detected on the surface of Porphyra thalli by immunofluorescence assay. The specificity of theseantibodies and the efficacy of immunofluorescence assay in the detectionof red rot disease are discussed.     

DEVELOPMENTAL STUDIES IN PORPHYRA (RHODOPHYCEAE). III. EFFECT OF CULTURE CONDITIONS ON WALL REGENERATION AND DIFFERENTIATION OF PROTOPLASTS1

Protoplasts isolated from thalli of four Porphyra species regenerated successfully into differentiated plantlets. The efficiency of protoplast isolation and the developmental patterns of the regenerating protoplasts depended on the type of tissues from which they were isolated. However, culture conditions greatly influenced the patterns of development at the cellular and organismal levels. Sorbitol, nitrogen, and agar concentration in the medium controlled rates of cell division, thickening of cell walls, development of rhizoids, and formation of calluses or differentiated blades. Agitation disturbed the attachment of the protoplasts to a substrate. Cells in agitated cultures produced suspensions of single cells and non-polarized small calluses. Calluses which developed from protoplasts survived in storage for over two years. The stored calluses, and cells and protoplasts that were isolated from them, were subcultured successfully. We forsee extensive use of Porphyra cell suspensions for strain selection and vegetative propagation of cultivars. This technology, which makes vegetative cloning of selected Porphyra plants possible, may eliminate the need for cultivation and storage of the conchocelis phase. Protoplasts are also being used as tools for studies in genetic engineering of these commercial species.     

Effect of harvest method and timing on yield and regeneration of Karengo (Porphyra spp.) (Bangiales,Rhodophyta) in New Zealand

Commercial interest in harvesting wild stocks ofPorphyra and concern for this prized resource by the Maori community highlighted the need to investigate the impact of harvest method and timing onPorphyra beds. Harvesting trials were carried out at two locations near Kaikoura (South Island) and one in Wellington (southern North Island) between June 1987 and September 1987. At each of five sampling sites, ten replicate sets of four quadrats were used to test the effects of harvest method and timing on yield and regeneration. The method of harvest had a major effect on the extent of regeneration: in quadrats in which thePorphyra had been cut with basal portions left intact there were harvestable plants within two months, whereas in quadrats which were cleared of allPorphyra there was very little growth after the same period. Harvests in the latter half of thePorphyra growing season gave greater yields at all sites except Wellington. Several species ofPorphyra were found to exist at the Kaikoura sampling sites and a single, different, species at the Wellington site. There were site to site differences in the yields.     

Experimental tank cultivation of Porphyra in Israel

Outdoor tank cultivation of several Porphyra (nori) species was carried out from late November 2002 through early May 2003 using 40 L (with a surface of 0.25 m²), 600 L (1 m²), and 24,000 L (30 m²) fiberglass or PVC tanks provided with continuous aeration and seawater flow. Sexual and asexual spores produced from cultured conchocelis and frozen thalli in the laboratory, respectively, were subsequently grown to produce young fronds (ca. 5-10 cm) in an average time of 8 weeks. Growth in outdoor tanks and ponds was possible for a period of up to 20 weeks (i.e. growth season), with yields above 100 g FW m⁻²d⁻¹occurring during 12-14 weeks from late December through late March, when seawater temperatures were below 20 ^∘ C. These yields correlated with the species and depended on the type of tanks in which the algae were cultivated, with the highest yields observed for Porphyra sp. and Porphyra yezoensis when fertilized twice a week with NH₄ Cl and NaH₂ PO₄in 40 L tanks. Calculations of productivity for an entire growth season based on ≥ 100 g FW m⁻²d⁻¹yields exceed the average productivities using seeded nets in open sea, for all Porphyra species tested (0.96-4.06 kg DW m⁻² season⁻¹vs. 0.7-1.0 kg DW m⁻²of net season⁻¹). Therefore, tank cultivation of Porphyra can offer an additional source of nori biomass to international markets. Land-based tank cultivation also offers an environmentally friendly practice that allows for the manipulation of growth conditions to enrich seaweeds with specific, valuable chemicals such as protein and minerals.     

Inter- and intrapopulation genetic variation in species ofPorphyra (Rhodophyta: Bangiales) from British Columbia and adjacent waters

Starch gel electrophoresis of 17 proteins has provided data on inter- and intrapopulation genetic variation in 20 species ofPorphyra occurring in British Columbia and adjacent areas.P. cuneiformis andP. nereocystis showed no within species variation, even over ranges of more than 1000 km. Populations ofP. abbottae, P. fallax, P. fucicola, P. gardneri andP. schizophylla were characterized by fixation for certain alleles. The number of polymorphic loci in a population ranged from zero to nine, depending on the species. Six species had populations that were polymorphic at just a single locus. Only two species (P. mumfordii andP. pseudolanceolata) had populations that were polymorphic at more than three loci. These levels of genetic variation are lower than those reported for populations of JapanesePorphyra species. Eleven taxa were polymorphic for 6-phosphogluconate dehydrogenase, the most variable enzyme. No within species polymorphisms were detected for bromoperoxidase, lactate dehydrogenase, superoxide dismutase or phycoerythrin. Possible evidence for the chimeric nature of the thallus was observed only inP. mumfordii.     

CRYOPRESERVATION OF THE CONCHOCELIS OF PORPHYRA (RHODOPHYTA) BY APPLYING A SIMPLE PREFREEZING SYSTEM1

The conchocelis cells of four strains of Porphyra yezoensis Udea and four other Porphyra species were cryopreserved in liquid nitrogen (LN) using a programmable freezer or a simple prefreezing system, which consisted of a styrofoam box and a deep-freezer at ?40° C. The cells differed in their freezing tolerance but survived maximally when prefrozen to ?40° C in a cryoprotective solution composed of 10% dimethylsulfoxide and 0.5 M sorbitol in 50% seawater. The cryopreservation was successfully performed by applying the simple prefreezing system as well as by a programmable freezer. Conchocelis cells thawed from the LN temperature formed colonies and retained the ability to form conchospores that grew into gametophytic thalli. This technique using a simple prefreezing system will accelerate the spread of Porphyra cryopreservation.     

Development of a transplantation technique of Cystoseira amentacea var. stricta and Cystoseira compressa

On the North-Western Mediterranean coastline, the genus Cystoseira (Fucales) has a key role on upper infralittoral community structure. Cystoseira amentacea var. stricta and C. compressa are the most common superficial Cystoseira species. In this area, the coastline is subjected to a strong anthropogenic pressure which has caused severe Cystoseira population decreases. The present study consists in the development of a cheap and easy to use transplantation technique of C. amentacea var. stricta and C. compressa in order to either restore former natural populations or help their settlement on artificial substrates. The thalli were fixed with epoxy glue in holes made by a drill. The success of the technique was assessed by counting the number of remaining transplanted thalli after 3 weeks, 3 months and 6 months. Results were found encouraging with 75% of survival for both species after 6 months. Moreover fertile fronds were observed on the transplanted thalli showing the harmlessness of the technique.     

Taxonomy, molecular phylogeny, and ultrastructural morphology of Olpidiopsis porphyrae sp. nov. (Oomycetes, straminipiles), a unicellular obligate endoparasite of Bangia and Porphyra spp. (Bangiales, Rhodophyta)

Olpidiopsis porphyrae sp. nov., a marine oomycete endoparasite that infects the commercially cultivated red alga Porphyra yezoensis, is described and its phylogenetic position based on molecular data and ultrastructural morphology is discussed. O. porphyrae infects the host Porphyra by means of encysted zoospores. Spherical-shaped holocarpic thalli develop within the cytoplasm of its algal host, which produce monoplanetic, subapically biflagellate zoospores. The characteristic features of this isolate are the ellipsoidal, unicellular thallus and simple holocarpic zoosporangial development, which show morphological similarity with the genus Olpidiopsis. Laboratory infection experiments with a wide range of green, brown, and red algae revealed that O. porphyrae infects several stages of the bangialean red algae (the genera Bangia and Porphyra). Molecular phylogenetic analyses inferred from both SSU rRNA and cox2 genes showed O. porphyrae branched before the main saprolegnian and peronosporalean lineages within the monophyletic oomycete clade, indicating its phylogenetic separation from them. A single or double K-body-like organelle, which contains tubular inclusions, is found located to one side of the zoospore nucleus and shows similarities to homologous organelles previously described in O. saprolegniae. The ultrastructural morphology of O. porphyrae with zoospore initials containing K-bodies and tubular mitochondrial cristae is characteristic of oomycetes. Group I intron-like multiple insertions were found in the SSU rRNA gene of O. porphyrae. This is the first report of SSU group I introns in the class Oomycetes.     

Rates of photosynthesis of two lichens and of their isolated algal components

Abstract

The rate of photosynthesis of two lichen species (Peltigera leucophlebia and Ramalina farinacea) was found to be 30 to 40% that of spinach leaf dises and 20% that of the free-living alga Chlorella when the results were expressed on a per mg chlorophyll basis. When the algae were isolated from the thalli, the rate of photosynthesis per mg chlorophyll increased for Ramalina farinacea and decreased for Peltigera leucophlebia. Product analysis indicated that the products of photosynthesis depended on the association of the alga with the fungus: algae isolated from the thalli showed a «shift» in products from sugars and sugar alcohols. to compounds such as organic acids. The results suggest that a symbiotic relationship with a fungus alters both the rate and products of algal photosynthesis.     

A NEW LOOK AT AN ANCIENT ORDER: GENERIC REVISION OF THE BANGIALES (RHODOPHYTA)1

The red algal order Bangiales has been revised as a result of detailed regional studies and the development of expert local knowledge of Bangiales floras, followed by collaborative global analyses based on wide taxon sampling and molecular analyses. Combined analyses of the nuclear SSU rRNA gene and the plastid RUBISCO LSU (rbcL) gene for 157 Bangiales taxa have been conducted. Fifteen genera of Bangiales, seven filamentous and eight foliose, are recognized. This classification includes five newly described and two resurrected genera. This revision constitutes a major change in understanding relationships and evolution in this order. The genus Porphyra is now restricted to five described species and a number of undescribed species. Other foliose taxa previously placed in Porphyra are now recognized to belong to the genera Boreophyllum gen. nov., Clymene gen. nov., Fuscifolium gen. nov., Lysithea gen. nov., Miuraea gen. nov., Pyropia, and Wildemania. Four of the seven filamentous genera recognized in our analyses already have generic names (Bangia, Dione, Minerva, and Pseudobangia), and are all currently monotypic. The unnamed filamentous genera are clearly composed of multiple species, and few of these species have names. Further research is required: the genus to which the marine taxon Bangia fuscopurpurea belongs is not known, and there are also a large number of species previously described as Porphyra for which nuclear SSU ribosomal RNA (nrSSU) or rbcL sequence data should be obtained so that they can be assigned to the appropriate genus.     

Rapid DNA extraction from conchocelis and ITS-1 rDNA sequences of seven strains of cultivated Porphyra yezoensis (Bangiales, Rhodophyta)

In order to extract DNA rapidly from cultivated Porphyra, we extracted total DNA from conchocelis using the ISOPLANT II kit (Nippon Gene) without liquid nitrogen treatment or CsCl-gradient ultracentrifugation. By confirming the reproducibility of RAPD patterns, it is concluded that the quality of the extracted DNA is sufficient to use as a template for molecular investigation. Using this rapid method, the nuclear ribosomal DNA of the internal transcribed spacer (ITS) regions was amplified from seven strains of cultivated Porphyra, which had been maintained as free-living conchocelis by subculturing in the laboratory. From the amplified DNAs, the ITS-1 sequences were determined in order to identify the species and genetic relationship of the strains. The sequences were identical in the seven strains, and all the strains were identified as P. yezoensis. Furthermore, the gametophytic blades of these strains showed long linear or oblanceolate shapes in the laboratory culture. It was concluded that these strains are P. yezoensis form. narawaensis. This rapid DNA extraction method from conchocelis will be a powerful tool for phylogenetic analysis and for genetic improvement of cultivated Porphyra.     

A simple restriction fragment length polymorphism (RFLP) assay to discriminate common Porphyra (Bangiophyceae, Rhodophyta) taxa from the Northwest Atlantic

The identification of Porphyra species hashistorically been difficult because of the lack of distinguishing morphologicaland ecological characters. We developed a restriction fragment lengthpolymorphism (RFLP) assay, based on inter-specific sequence variation inthe ribulose bisphosphate carboxylase oxygenase largesubunit (rbcL) gene andrbcL-rbcS intergenic spacer, toprovide a simple and effective tool for screening and sorting large collectionsof Porphyra from the Northwest Atlantic. A singlerestriction digest (Hae III) discriminates betweenmultiplePorphyra species including one cryptic taxon; anadditionalenzyme (Hind III) was necessary to distinguish between theclosely related P. leucosticta and an introducedspecies P. yezoensis.     

VARIATIONS IN THE CELL WALLS AND PHOTOSYNTHETIC PROPERTIES OF PORPHYRA YEZOENSIS (BANGIALES,RHODOPHYTA) DURING ARCHEOSPORE FORMATION1

The formation of archeospores is characteristic of Porphyra yezoensis Ueda and is important for Porphyra aquaculture. Recently, it has been regarded as a valuable seed source for propagation of thalli in mariculture. Cell wall composition changes are associated with archeospore formation in P. yezoensis. Here, we report changes of cell walls of P. yezoensis during archeospore formation. The surfaces of vegetative cells that were originally smooth became rougher and more protuberant as archeosporangia were formed. Ultimately, the cell walls of archeosporangia ruptured, and archeospores were released from the torn cell walls that were left at distal margins of thalli. With changes in cell walls, both effective quantum yield and maximal quantum yield of the same regions in thalli gradually increased during the transformation of vegetative cells to archeospores, suggesting that the photosynthetic properties of the same regions in thalli gradually increased. Meanwhile, photosynthetic parameters for different sectors of thalli were determined, which included the proximal vegetative cells, archeosporangia, and newly released archeospores. The changes in photosynthetic properties of different sectors of thalli were in accordance with that of the same regions in thalli at different stages. In addition, the photosynthetic responses of archeosporangia to light showed higher saturating irradiance levels than those of vegetative cells. All these results suggest that archeosporangial cell walls were not degraded prior to release but were ruptured via bulging of the archeospore within the sporangium, and ultimately, archeospores were discharged. The accumulation of carbohydrates during archeospore formation in P. yezoensis might be required for the release of archeospores.     

Autecological studies of the genus Porphyra

Among the algal associations of exposed northern shores in Britain, those formed by species of the genus Porphyra deserve greater recognition than has so far been accorded to them. The present paper discusses some of the taxonomic criteria of this plastic genus and delimits five species which are widespread on northern British shores.     

Three New Species of Brevibacteria,Brevibacterium antiquum sp. nov., Brevibacterium aurantiacum sp. nov., and Brevibacterium permense sp. nov.

This work deals with the taxonomic study of orange-pigmented bacteria isolated from permafrost sediments, rice plots, and soils contaminated with wastes from the chemical and salt industries that were assigned to the genus Brevibacterium on the basis of phenotypic characteristics, as well as of some strains described previously as Brevibacterium linens. The study revealed three genomic species, whose members and the type strains of the closest species of Brevibacterium had DNA similarity levels between 24 and 59%. The strains of the genomic species differed from each other and from the known species of Brevibacterium in some physiological and biochemical characteristics, as well as in the sugar and polyol composition of their teichoic acids. The 16S rDNA sequence analysis confirmed the assignment of the environmental isolates to the genus Brevibacterium and showed the phylogenetic distinction of the three genomic species. The results obtained in this study allow three new Brevibacterium species to be described: Brevibacterium antiquum (type strain VKM Ac-2118^T = UCM Ac-411^T), Brevibacterium aurantiacum (type strain VKM Ac-2111^T = NCDO 739^T = ATCC 9175^T), and Brevibacterium permense (type strain VKM Ac-2280^T = UCM Ac-413^T).     

ThePorphyra species of Helgoland (Bangiales,Rhodophyta)

This revision of sevenPorphyra species of Helgoland was based on a study of the structure of their fertile thalli and the behaviour of their spores. Regarding the reproductive organization the species may be arranged in two groups.P. leucosticta andP. purpureo-violacea are obligate monoecious species. Asexual thalli have never been observed in the field. The other five species are generally dioecious. Isomorphic sexual thalli and asexually propagating ones are mixed in uniform populations. Carpospores originating from sexual fusion develop into the diploid Conchocelis phase. Sporangia of asexual plants, though homologous in formation, produce spores of different kinds: aplanospores that give rise to the vegetative thallus directly (inP. umbilicalis, P. insolita n. sp. andP. ochotensis) and spores that develop into haploid Conchocelis (inP. laciniata and inP. linearis). P. laciniata — formerly considered synonymous withP. purpurea — is an independent species. “In an investigation into the life-history of an alga the aim should be to obtain a series of observations of the development of the thallus from the germinating spore and then of the development of the reproductive organs on the mature thallus. In cases where both sexual and asexual spores are formed the germination of both types of spore should be followed, ...” (Drew, 1954, p. 184)