Morphology and life history of Halopteris filicina (Sphacelariales, Phaeophyceae) from Korea

The vegetative morphology and life history of Halopteris filicina (Grateloup) Kutzing, collected from Korea, were examined in laboratory culture. Field plants attaining 3–5 cm in height were epilithic, tufted, yellowish-brown, and produced numerous erect axes with alternately distichous branches from compact basal discs. They were cultured under a 12:12 h LD photoperiod at 10°-C, 15°C and 20°C to observe the influence of temperature on reproduction. At 10°C plants grew only vegetatively, whereas at 15°C and 20°C they produced unilocular sporangia. Unispores released from sporangia developed into monoecious, anisogamous gametophytes that formed plurilocular female and male gametangia on the same lateral branches. The zygotes, by fusion of female macrogametes and male microgametes, developed into sporophytes bearing unilocular sporangia, whereas the unfused female gametes germinated parthenogenetically. This species was confirmed to have an isomorphic life history, basically similar to the other species of Sphacelariales.     

Observations on some Crysophyceae from North Wales

An examination by means of electron microscopy of phytoplankton samples from 23 localities in North Wales and Anglesey yielded 14 species of Synuraceae. Eleven of these have not been recorded previously from this region, and two species are new to Britain, viz. Mallomonas pugio Bradley and Spiniferomonas trioralis Takahashi.     

Galactan sulfate of Grateloupia indica: Isolation, structural features and antiviral activity

Natural compounds offer interesting pharmacological perspectives for antiviral drug development with regard to broad-spectrum antiviral properties and novel modes of action. In this study, we have analyzed polysaccharide fractions isolated from Grateloupia indica. The crude water extract (GiWE) as well as one fraction (F3) obtained by anion exchange chromatography had potent anti-HSV activity. Their inhibitory concentration 50% (IC₅₀) values (0.12-1.06 μg/ml) were much lower than cytotoxic concentration 50% values (>850 μg/ml). These fractions, which were effective antiviral inhibitors if added only during the adsorption period, had very low anticoagulant activity. Furthermore, they had no direct inactivating effect on virions in a virucidal assay. Chemical, chromatographic and spectroscopic methods showed that the active polysaccharide, which has an apparent molecular mass of 60 kDa and negative specific rotation −16° (c 0.2, H₂O), contains α-(1 → 4)- and α-(1 → 3)-linked galactopyranose residues. Sulfate groups, if present, are located mostly at C-2/6 of (1 → 4)- and C-4/6 of (1 → 3)-linked galactopyranosyl units, and are essential for the anti herpetic activity of this polymer.     

TWO TYPES OF AUXILIARY CELL AMPULLAE IN GRATELOUPIA (HALYMENIACEAE,RHODOPHYTA), INCLUDING G. TAIWANENSIS SP. NOV. AND G. ORIENTALIS SP. NOV. FROM TAIWAN BASED ON rbcL GENE SEQUENCE ANALYSIS AND CYSTOCARP DEVELOPMENT1

Few species in the genus Grateloupia have been investigated in detail with respect to the development of the auxiliary cell ampullae before or after diploidization. In this study, we document the vegetative and reproductive structures of two new species of Grateloupia, G. taiwanensis S.‐M. Lin et H.‐Y. Liang sp. nov. and G. orientalis S.‐M. Lin et H.‐Y. Liang sp. nov., plus a third species, G. ramosissima Okamura, from Taiwan. Two distinct patterns are reported for the development of the auxiliary cell ampullae: (1) ampullae consisting of three orders of unbranched filaments that branch after diploidization of the auxiliary cell and form a pericarp together with the surrounding secondary medullary filaments (G. taiwanensis type), and (2) ampullae composed of only two orders of unbranched filaments in which only a few cells are incorporated into a basal fusion cell after diploization of the auxiliary cell and the pericarp consists almost entirely of secondary medullary filaments (G. orientalis type). G. orientalis is positioned in a large clade based on rbcL gene sequence analysis that includes the type species of Grateloupia C. Agardh 1822 , G. filicina. G. taiwanensis clusters with a clade that includes the generitype of Phyllymenia J. Agardh 1848 , Ph. belangeri from South Africa; that of Prionitis J. Agardh 1851 , Pr. lanceolata from Pacific North America; and that of Pachymeniopsis Y. Yamada ex Kawab. 1954, Pa. lanceolata from Japan. A reexamination of the type species of the genera Grateloupia, Phyllymenia, Prionitis, and Pachymeniopsis is required to clarify the generic and interspecific relationships among the species presently placed in Grateloupia.     

Reinstatement of Grateloupia subpectinata (Rhodophyta, Halymeniaceae) based on morphology and rbcL sequences

Morphological observations and molecular analyses of the north‐western Pacific species of the red algal genus Grateloupia (Halymeniaceae) indicate the presence of an entity, which is somewhat similar in gross morphology to G. asiatica Kawaguchi et Wang but is distinguished from the latter species by some morphological features. These include: (i) a somewhat fleshy texture; (ii) wider and much thicker (4.5–10 mm wide and up to 1300 μm thick) axes, of which an inner cortex consists of more (6–9) cells; (iii) generally longer (up to 17 cm), marginal and surface proliferations that are clearly constricted (terete) at bases; and (iv) much elongated, oblong auxiliary cells. Phylogenetic analysis using the ribulose‐l,5‐bisphosphate carboxylase/ oxygenase (rbcL) gene of G. asiatica and the alga in question shows them to be distantly related and strongly supports the differentiation of these two entities at the species level. Judging from the literature, this entity is actually Grateloupia subpectinata Holmes, which has been placed into synonymy under G. asiatica [as G. filicina (Lamouroux) C. Agardh] or G. prolongata J. Agardh in previous reports, and therefore the Holmes name is reinstated.     

Morphogenetic effect of glycerol on tissue cultures of the red seaweed Grateloupia doryphora

Explants of Grateloupia doryphora were cultivated in Provasoli Enriched Seawater culture medium (PES) supplemented with glycerol (0.1, 0.3, 0.5 or 0.8 mol 1^–1) or carbohydrates (0.1 or 0.3 mol 1^–1 mannose, glucose and galactose) and agar (3, 8, 15 g 1^–1 ). The osmolality of the medium was adjusted by dilution of the seawater (70 or 100%, v/v). The increase in fresh weight of explants cultivated in liquid medium with glycerol (0.3 mol 1^–1) and without glycerol was compared. All experiments were carried out in the light, except for one assay in which the explants were cultivated in the dark. Glycerol was an effective carbon source for the vegetative propagation of G. doryphora in solid and liquid media. Mannose, glucose and galactose all had no effect on growth or morphogenesis of the explants. In solid media the main effect of glycerol was as a morphogenetic inductor, with PES70 (70% seawater) + 0.1 or 0.3 mol 1^–1 glycerol + 3 or 8 g 1^–1 agar the best formulation. An increase in the concentration of agar in glycerol-containing medium reduced the morphogenetic capacity of the explants, which developed into compact cell masses. The effects of glycerol were observed only in explants cultivated under light.     

Influence of plant growth regulators, polyamines and glycerol interaction on growth and morphogenesis of carposporelings of Grateloupia cultured in vitro

The influence of the plant growth regulators 2,4-D, GA₃, BA and kinetin, and the polyamines putrescine, spermidine and spermine were tested on axenic in vitro cultures of carposporelings of Grateloupia doryphora. The auxin 2,4-D (10^-3 M) and the polyamine spermine (10^-6 M and 10^-3 M) induced a callus (disorganised cell mass that arose from the organised tissue of the carposporeling, as demonstrated by microscopic monitoring of the tissue). Putrescine and spermidine (10^-3 M) transformed the carposporelings into cell masses that produced shoots. BA (10^-3 M) and kinetin (10^-6 M and 10^-3 M) were inhibitory. In 10^-1 M glycerol-containing culture medium, which is known to induce the formation of morphogenic cell masses, the addition of GA₃ M) resulted in the inhibition of the morphogenesis (i.e. shoot emission) in the cell mass. The kinetin at 10^-6 M inhibited morphogenesis, whilst at 10^-3 M inhibited even the formation of the cell masses. The combination of glycerol (10^-1 M) and the auxin 2,4-D (10^-6 and 10^-3 M) or the polyamines putrescine, spermidine and spermine (10^-6 and 10^-3 M) resulted in a bigger size of the cell masses that led to a higher amount of shoots per cell mass than in glycerol alone. This revised version was published online in June 2006 with corrections to the Cover Date.     

Production and application of filaments of <Emphasis Type="BoldItalic">Grateloupia turuturu</Emphasis> (Halymeniaceae,Rhodophyta)

Filaments from Grateloupia turuturu were obtained through germination of spores, regeneration from fragments of discoid crusts and erect thalli. The rates of filament formation through the three ways were 5.3 ± 1.2%, 100%, and 62.3 ± 5.6%, respectively. Discoid crusts were the best materials for the production of filaments. The obtained filaments were cloned in stationary and aerated culture. The differentiations of filaments were observed. When attached to the substrata, filaments differentiated into discoid crusts from which erect thalli grew, whereas for filaments in suspension culture, some cells in the filaments differentiated into spherical structures that also formed new erect thalli. Moreover, fragments of filaments (< 100 μ m) were seeded onto nori-nets. The regenerated plantlets grew into adult thalli in field cultivation.     

GENETIC VARIABILITY AND POTENTIAL SOURCES OF GRATELOUPIA DORYPHORA (HALYMENIACEAE,RHODOPHYTA), AN INVASIVE SPECIES IN RHODE ISLAND WATERS (USA)1

Grateloupia doryphora (Montagne) M.Howe is an invasive foliose alga that was reported for the first time in Rhode Island, USA in 1997. The population has since increased in size and expanded in range. In this study, the genetic variation and potential sources of the Rhode Island G. doryphora population were examined using three types of molecular markers: randomly amplified polymorphic DNA (RAPD), nuclear internal transcribed spacer (ITS) sequences, and mitochondrial cox2–cox3 intergenic spacer (COX) sequences. No variation was detected in ITS or COX sequences among Rhode Island G. doryphora individuals. RAPDs, however, did reveal genetic variation, although banding patterns were similar, with RAPD genetic distances between individuals ranging from 0.00 to 0.17. The low level of genetic diversity observed within the Rhode Island population may be due to a small founder population or a founder population derived from a genetically uniform source. To identify possible sources of the Rhode Island invasion, individuals from nine geographically diverse populations of foliose Grateloupia were compared. Phylogenetic trees inferred from RAPD distances and ITS and COX sequences had similar topologies; thus there was phylogenetic congruence among these independent loci. The Rhode Island G. doryphora specimens were genetically similar to specimens from G. doryphora populations located in Portsmouth, England; Tholen Island, The Netherlands; and Brittany and Hérault, France. Interestingly, the G. doryphora population in each of these locations is itself due to an introduction event within the past 40 years.     

A COMPARATIVE STUDY OF THE RED ALGA GRATELOUPIA FILICINA (HALYMENIACEAE) FROM THE NORTHWESTERN PACIFIC AND MEDITERRANEAN WITH THE DESCRIPTION OF GRATELOUPIA ASIATICA, SP. NOV.

Morphological observations and molecular analyses of the red alga Grateloupia filicina (Halymeniaceae) from two geographically distant regions, eastern Asia (Japan and northern China) in the northwestern Pacific and Italy in the Mediterranean, reveal the presence of two distinct entities. Morphologically, the eastern Asian entity differs substantially from the Italian entity in the following ways: 1) thin and soft thalli with wider axes, 2) denser medullary filaments, 3) scattered reproductive structures over the entire thallus, and 4) a mature auxiliary cell that is oval and slightly larger than other ampullary cells. Phylogenetic analysis based on the ribulose-1,5-bisphosphate carboxylase/oxygenase gene ( rbc L) sequences revealed that the eastern Asian and Italian entities are phylogenetically far apart, strongly supporting the differentiation of these two entities at the species level. The eastern Asian entity is therefore described as a new species, Grateloupia asiatica. This species can be distinguished from most known species of Grateloupia that have widely flattened thalli by its compressed to narrowly flattened axes with numerous pinnate proliferations and from a few species with similar thalli by a particular combination of features, including a gelatinous texture, mostly simple and narrower axes, a thinner cortex, and the absence of catenate proliferations.