Planktonic bloom of an introduced species of Polysiphonia (Ceramiales,Rhodophyta) along the coast of North Carolina,USA

Analysis was made of the species composition, egg number per female and the size-frequency of Amphipoda living on the dominating submerged macrophytes (Potamogeton perfoliatus and Myriophyllum spicatum) at 10 sampling stations of the northern and southern shoreline of Lake Balaton. The dominating Amphipoda at each sampling station was Corophium curvispinum (85.9–99.8%, mean: 96.6%). Besides this, two other species — Dikerogammarus haemobaphes and D. villosus — were also found in the samples. The two Dikerogammarus species were found in highest percentage near Keszthely (14.1 %); at the other places studied they were under 5%. The number of Amphipoda individuals per g macrophyte dry weight ranged from 5 to 574; the lowest value was found near Keszthely, the highest near B. Mária. The developmental stages of the C. curvispinum population differ in different parts of Lake Balaton: the adult (male and female) specimens occurred in highest percentage near Keszthely. The mean number of eggs per C. curvispinum female ranged from 2.4 to 6.3, showing differences at the different sampling stations. Regarding the two Dikerogammarus species, there were many more D. haemobaphes than D. villosus individuals at almost every station (mean: 75%). The mean number of eggs per egg-carrying female of D. haemobaphes was 11.7, being 19.1 for D. villosus.The total biomass of amphipods (in mg animal dry weight/g macrophyte dry weight) ranged from 1.2 to 59.8. The lowest value was observed near Keszthely (the most hypertrophic basin of Lake Balaton), the highest value near B. Maria     

Agarans from the red seaweed Polysiphonia nigrescens (Rhodomelaceae, Ceramiales)

Polysiphonia nigrescens was sequentially extracted with water at room temperature, 70 and 90 degrees C. The extracts were analyzed and the major one, isolated at 70 degrees C, was fractionated by ion-exchange chromatography, eluting with water and solutions of increasing sodium chloride concentration; five main fractions were separated. Structural analysis, carried out by methylation analysis and NMR spectroscopy, showed that four of these were partially cyclized agarans that were highly substituted on C-6 mainly with sulfate, although methyl ether and single stubs of beta-D-xylose were found in minor proportions. A fifth fraction comprising 6-sulfated agarose was also isolated. The use of 2D NMR techniques allowed us to assign the 1H and 13C NMR resonances of the G6S-->L6S diad for the first time.     

Actin-mediated chloroplast movement in Griffithsia pacifica (Ceramiales, Rhodophyta)

Chloroplast banding occurs in Griffithsia pacifies Kylin in a daily rhythm. At the start of the light period, chloroplasts have a uniform distribution. During the light period chloroplasts move away from the ends of the cell leaving two chloroplast-free regions by mid-afternoon. Later in the light period these bands disperse as chloroplasts return to the ends of cell where they remain throughout the dark period. After enzyme treatment with β-glucuronidase to permeabilize cell walls, non-banded plants did not form bands after the addition of 5 μg ml^?1 cytochalasin B in dimethyl sulfoxide (DMSO). When enzyme-grown plants with chloroplast bands were treated with cytochalasin B, bands were retained for at least three days. Plants grown in media supplemented with β-glucuronidase or DMSO alone gave banding consistent with untreated controls. Staining of microfilaments with rhodamine-phalloidin before and after treatment with cytochalasin B gave results consistent with chloroplast movement studies. This is the first report of actin-mediated organelle movement in red algae.     

The xylogalactan sulfate from Chondria macrocarpa (Ceramiales,Rhodophyta)

A structure is proposed for the complex xylogalactan sulfate from Chondria macrocarpa. The hot-water extract of C. macrocarpa was desulfated or alkali-treated and Smith degraded. Constituent sugars and their substitution patterns were identified using a modified Hakamori methylation procedure suited to sulfated polysaccharides and a double hydrolysis-reduction protocol that yielded derivatives from all of the sugar residues, including the labile 3,6-anhydrogalactosyl residues. The polymer has an agar-type backbone of alternating 3-linked \-d- and 4-linked -L-galactopyranosyl units. The d-residues are partially sulfated on O-2 (50%) and O-6 (20–30%). About 40% of the l-residues are present as the 3,6-anhydride and 25% as its precursor l-galactose 6-sulfate. A significant proportion of the remaining l-galactosyl residues have both a d-xylopyranosyl substituent on O-3 and a sulfate ester on O-6 and are stable to alkali.     

Developmental morphology of Odonthalia floccosa (Ceramiales, Rhodophyta) in laboratory culture

Material of the red alga Odonthalia floccosa (Esper) Fal-kenberg (Rhodomelaceae, Ceramiales), collected from California, was cultured in the laboratory and its life-history was completed. Tetraspores grew into bipolar sporelings that differentiated into a colorless rhizoidal portion and a pigmented upright shoot. The sporelings became compressed apically and formed lateral branches in a regularly distichous manner that were congenitally fused with the main axis. These tetraspore germlings grew into diecious gametophytes. Male ga-metophytes produced numerous spermatangia on modified fertile branchlets (male trichoblasts) that possessed three to four monosiphonous, proximal segments. Female gametophytes formed a single pro-carp on the suprabasal segment of unbranched female trichoblasts. Cystocarps developed on the female gametophytes cocultured with male gametophytes and released viable carpospores that developed into fertile te-trasporophytes. Tetrasporangia were produced from the third and fourth periaxial cells in each of 12–45 successive fertile segments and provided three (two lateral and one basal) cover cells. The occurrence of both spermatangia and procarps on fertile trichoblasts in O. floccosa suggests that the alga is the most derived in these two characters among the species of the genus Odonthalia. This species is distributed in cold temperate regions in the North Pacific, and it should be excluded from the North Atlantic marine algal flora.     

Additional analysis of chemical diversity in Laurencia nipponica (Ceramiales, Rhodophyta)

The red alga Laurencia nipponica Yamada (Rhodomelaceae, Ceramiales) is known to contain several chemical races, each of which is characterized by a particular, major halogenated secondary metabolite. Both field-collected and cultured plants of a population of this species found recently at Shikanoshima Island, Fukuoka Prefecture, southern Japan, produced C₁₅ bromoethers, (3E)-laureatin and (3E)-isolaureatin, and sesquiterpenoids, 2,10-dibromo-3-chloro-9-hydroxy-α-chamigrene and 2,10-dibromo-3-chloro-α-chamigrene. Laurencia nipponica can be referred to as a further chemical race that is characterized by the production of two C₁₅ bromoethers, (3E)-laureatin and (3E)-isolaureatin, and a sesquiterpenoid, 2,10-dibromo-3-chloro-9-hydroxy-α-chamigrene as major compounds.     

Seasonal variations in sterol composition of Delesseria sanguinea (Ceramiales,Rhodophyta)

On Normandy coasts, the red alga Delesseria sanguinea perennates by its stipe; fronds grow in January and disappear in June. Seasonal variations in sterol composition in relation to the biology of D. sanguinea are reported. Sterols in cellular membranes are free or conjugated by esterification with fatty acids, heterosides or lipid complexes like phospholipids. Both kinds of sterols were analyzed by GC-MS. The major sterol (80%) found in fronds was cholesterol whereas in stipes, cholesterol was also the major sterol in spring, but in September, an important reduction in cholesterol yield was noted with proportional increase in sitosterol content. It appears that cholesterol is synthesized in fronds in spring, then transferred to the stipe, which loses an important amount of cholesterol with loss of the blades.     

Physiological responses of Caloglossa leprieurii (Ceramiales, Rhodophyta) to salinity stress

Marine, estuarine and freshwater isolates of Caloglossa leprieurii (Montagne) J. Agardh exhibit a high salinity tolerance, reflected by broad cell viability and growth rate. Osmotic adjustment is shown to rely to a large extent on ion-transport systems, with K⁺ and Cl- accumulated in osmotically- significant quantities and active Na⁺ extrusion. The ion concentrations contribute a large proportion (67–94%) to internal osmotic pressure. The concentration of the organic osmolyte mannitol in all populations was strongly salinity dependent. Mannitol made a lower contribution to the internal osmotic pressure, when compared to ion concentrations, but nonetheless represented an important proportion of the internal osmolality. The response of the three isolates is discussed in relation to the salinity of their respective environments.     

Neorhodomela enomotoi sp. nov. (Ceramiales, Rhodophyta) from Japan

The red alga Neorhodomela enomotoi Masuda et Kogame (Rhodomelaceae, Ceramiales) is described as a new species from Japan. It is characterized by the following combination of features: (i) thalli reddish-brown and slightly rigid; (ii) first-order branches mostly indeterminately branched; (iii) adventitious branches infrequent, determinately branched and formed chiefly in the axils of lateral branches; (iv) vegetative trichoblasts abundant; (v) tetrasporangia produced on paniculate ultimate and penultimate branches; and (vi) cystocarps flask-shaped (urceolate). This species has been found growing only in the upper subtidal zone in the warm temperate waters of Japan.     

The reproductive structures of the Mediterranean alga Laurencia pelagosae (Ceramiales,Rhodophyta)

Reproductive structures of Laurencia pelagosae are described for the first time. Tetrasporangia, in parallel arrangement, are cut off from the mother cells adaxially; antheridial branches, which are unramified, are inserted in depressions lacking a row of axial cells on their bases; cystocarps are sessile and subspherical. The occurrence of secondary pit-connections between epidermal cells and of lenticular thickenings in the walls of medullary cells is documented. The species is included in the new section Pelagosae within the subgenus Laurencia.     

Growth and the content of laurinterol and debromolaurinterol in Laurencia okamurae (Ceramiales, Rhodophyta)

The growth of Laurencia okamurae and the content of laurinterol and debromolaurinterol were influenced by various factors. Temperature influenced growth raere te with a maximum at 25°C, regardless of daylength. Maturity depended on temperature rather than daylength; the plants grew without maturing at 15°C, while the plants matured within two weeks at 25°C. The plants were able to grow at salinities of 14–50‰ with maximum growth at 26‰. The salinities growth rash;50‰te reduced with decreasing concentration of nitrate below 1.2 × 10^-3 M, and of total phosphate below 7.5× 10^-8 M. Bromide concentration had no effect on growth, and the plants grew without bromide. Variation in temperature between 15–25°C and daylength produced no obvious change in laurinterol and debromolaurinterol contents. On the other hand, an increase in salinity led to an increase for both. The plants cultured in a completely artificial medium, modified ASP₁₂NTA, showed a marked drop in their content of these metabolites. An increase in concentrations of nitrate, total phosphate or bromide did not restore the content. This revised version was published online in June 2006 with corrections to the Cover Date.     

Purification and Characterization of Mannitol-l-Phosphatase in the Red Alga Caloglossa continua (Ceramiales, Rhodophyta)

Purification of mannitol-l-phosphatase, an enzyme catalyzing the final step of mannitol biosynthesis, was first achieved in the mannitol-accumulating red alga Caloglossa continua (Okamura) King et Puttock. The enzyme was shown to be a monomer, since gel filtration and sodium dodecyl sulfate–polyacrylamide gel electrophoresis gave close values of apparent molecular weights of 28,500 and 30,200, respectively. The protein exhibited an isoelectric point of 4.8. The substrate specificity for mannitol-l-phosphate (MIP) was very high, and that for K _m(MIP) was 0.41 mM. The catalytic activity was optimal at pH 7.4. The enzyme was activated by Mg²⁺, but was strongly inhibited by Ca²⁺, NaF, N-ethylmaleimide, and p-hydroxymercuribenzoic acid. Seawater levels of NaCl and physiological levels of mannitol also inhibited the activity by 50% or more. Changes in the concentrations of those ions and metabolites may regulate the biosynthesis of mannitol as an osmoregulant in vivo. Received May 7, 2001; accepted June 15, 2001.     

The cell wall chemistry of Bangia atropurpurea (Bangiales, Rhodophyta) and Bostrychia moritziana (Ceramiales, Rhodophyta) from marine and freshwater environments

The cell wall polysaccharides of two species of red algae, which are adapted to both freshwater and marine environments, were analysed to determine the effect of these widely different environments on their commercially important agarocolloids and to investigate the possible role of the cell wall in environmental adaptation. Cell wall polymers of freshwater isolates of Bangia atropurpurea (Roth) C. Agardh and cultured freshwater and marine Bostrychia moritziana (Sonder ex Kützing) J. Agardh were isolated and the polysaccharides chemically fractionated and characterized. Wall polysaccharides of freshwater B. atropurpurea were similar to those previously reported for marine isolates with repeating disac-charide units of agarose and porphyran predominant in the hot water extracts. In the insoluble residues, 3-iinked galactosyl and 4-linked mannosyl residues were predominant. Bostrychia moritziana wall polysaccharides included agarocolloids with various patterns of methyl ether substitution similar to those previously described for other Ceramiales. Differences in the position of methyl ether substituents were detected in the hot water extracts of the freshwater and marine specimens. Polymers of freshwater ß. moritziana cultures were composed of a complex mixture of repeating disaccharide units including 2′-O-methyl agarose, 6-O-methyI agarose and 2′-O-methyl porphyran. Polymers of marine isolates of ß. moritziana differ in that they contain only trace amounts of 2-O-methyl saccharides and increased amounts of 6-O-amethyl saccharides. The hot water insoluble residues of both freshwater and marine isolates of ß. moritziana contain a mixture of 3-linked galactosyl and 4-linked glucosyl residues. These results indicate that the adaptive response of B. moritziana to changing osmotic and ionic conditions may include changes in cell wall chemistry: notably, the pattern of methyl ether substitution.     

Polysiphonia freshwateri sp. nov. and Polysiphonia koreana sp. nov.: two new species of Polysiphonia (Rhodomelaceae,Rhodophyta) from Korea

Polysiphonia sensu lato comprises approximately 200 species, which are currently assigned to several different genera. To date, one of these genera, namely, Polysiphonia, has been reported to have 17 species. Here, we describe for the first time P. freshwateri sp. nov. and P. koreana sp. nov. from Uljin and Ulleung Island, Korea, based on morphological and molecular evidence. Polysiphonia freshwateri sp. nov. and P. koreana sp. nov. are characterized by having the typical Polysiphonia features. Polysiphonia freshwateri sp. nov. is further characterized by having abundant trichoblasts, conspicuous scar cells, and tetrasporangia arranged in spiral series. Polysiphonia koreana sp. nov. is further characterized by having very scarce scar cells placed between two pericentral cells, from which cicatrigenous branches arise. The results of our rbcL sequence analyses support the taxonomic placement of P. freshwateri sp. nov. and P. koreana sp. nov. within Polysiphonia.     

On three interesting marine red algae (Ceramiales,Rhodophyta) from the Mediterranean Sea

Abstract

Observations on three interesting Ceramiales from the Mediterranean Sea are reported; Ceramium incospicuum Zanardini, Polysiphonia setacea Hollenberg and Rodriguezella pinnata (Kützing) Schmitz ex Falkenberg. The male reproductive structures on the genus Rodriguezella are described for the first time.     

Modeling competition between Laurencia obtusa (Ceramiales,Rhodophyta) and Hypnea spinella (Gigartinales,Rhodophyta) at Cabo Frio Island,Rio de Janeiro,Brazil

The Lotka-Volterra competition model was used to represent the interaction between Laurencia obtusa and Hypnea spinella. A new model that considers effects of competition on algal carrying capacity is suggested. To test the models, data from field experiments conducted in an intertidal region at Cabo Frio Island, Rio de Janeiro, Brazil, were used. Both models showed that Hypnea was a stronger competitor than Laurencia. The model of interaction through the carrying capacity showed a stable coexistence between the algal populations and better represented the experimental data.     

The wound-healing responses of Antithamnion nipponicum and Griffithsia pacifica (Ceramiales, Rhodophyta) monitored by lectins

The binding of FITC labeled lectins to repair cells of Antithamnion nipponicum Yamada et Inagaki and Griffithsia pacifica Kylin, and their physiological effects on somatic cell fusion have been studied. Results indicate that repair cells strongly bind the lectins ConA and LCA, whereas other lectins did not bind to the cell, The binding of these lectins to the dead cell wall shows ConA and LCA specific substances are secreted from the tip of the repair cells. When fluorescently labeled ConA or LCA was added at various time intervals after wounding, it firstly bound (3 h post-wounding) as a thin layer at the tips of the adjacent cells. Later (4–5 h post-wounding) labeling also appeared at the tips of the repair ceils. Intense labeling at these sites continued throughout the wound-healing process until repair cell fusion, at which time the lectin labeling was reduced to a narrow ring around the area of fusion, When added to plants prior to wounding and with continued monitoring, these same lectins were found to act as inhibitors to the wound-healing response. Other control lectins showed no inhibitory effects. These results suggest that a signal glycoprotein with α-D-mannosyl residues is involved in the wound-healing process of Antithamnion nipponicum. Lectins conjugated with visible tags can be used as a very fast and useful tool to monitor these signal substances.     

Antithamnion makroklonion sp. nov. (Rhodophyta, Ceramiales) from the Gulf of Aqaba (Red Sea)

Antithamnion makroklonion sp. nov. is described from Elat, Gulf of Aqaba (Gulf of Elat) in the Red Sea, where vegetative, spermatangial, and tetrasporangial specimens were found growing in the upper sublittoral zone. The new alga belongs to a group of Antithamnion species characterized by distichous-alternate ramification of branches, sessile tetrasporangia, and decussately arranged laterals along the bearing axis. It shows a unique combination of distinctive features, including the proximal development of gland cells on elongate branchlets that overtop the parent branch. In addition to the characteristic position, and in contrast to congeners, gland cells of A. makroklonion often have a large and prominent cytoplasmic band and one or two vacuoles. Morphological features of A. makroklonion and eight related species are tabulated and the characteristics of the new species are discussed.     

Host specificity and growth of kelp gametophytes symbiotic with filamentous red algae (Ceramiales,Rhodophyta)

Kelp gametophytes were previously observed in nature living endophytically in red algal cell walls. Here we examine the interactions of two kelp species and six red algae in culture. Gametophytes of Nereocystis luetkeana (Mertens) Postels et Ruprecht became endophytic in the cell walls of Griffithsia pacifica Kylin and Antithamnion defectum Kylin, and grew epiphytically in high abundance on G. japonica Okamura and Aglaothamnion oosumiense Itono. Alaria esculenta (Linnaeus) Greville from the Atlantic coast of Nova Scotia became endophytic in Aglaothamnion oosumiense, Antithamnion defectum, Callithamnion sp., G. japonica, G. pacifica, and Pleonosporium abysicola Gardner, all from the Pacific Ocean. Some cultures were treated with phloroglucinol before infection to thicken the cell walls. The endophytic gametophytes were smaller and grew more slowly than gametophytes epiphytic on the same host. N. luetkeana failed to become endophytic in some of the potential hosts, and this may reflect host specificity, or culture artifacts. This work improves our understanding of the process of infection of red algae by kelp gametophytes, and broadens our knowledge of host specificity in endophytic symbioses.Communicated by K. Lüning