Ji-Young Cho

Multiple allelopathic activity of the crustose coralline alga Lithophyllum yessoense against settlement and germination of seaweed spores

A study was made to investigate possible formation by the crustose coralline algaLithophyllum yessoenseof multiple allelopathic-related substances against the settlement and germination of spores of various seaweeds. Seven different solvents (n-hexane, diethyl ether, acetone, ethyl acetate, acetonitrile, methanol, distilled water) and seawater were used to obtain crude extracts and secretory exudates from the coralline alga. The extracts and the algal conditioned seawater were tested for inhibitory activity against the settlement and germination of spores from 17 species representing 15 genera. Spore settlement of 14 species was inhibited over 90% by one or more extracts of the six organic solvents and conditioned seawater. The germination of spores from 13 species was inhibited by one or more extracts of all seven solvents and conditioned seawater. The species where spore settlement was not significantly affected showed strong inhibition of germination, andvice versa.

A procedure for axenic isolation of the marine microalga Isochrysis galbana from heavily contaminated mass cultures

Isochrysis galbana, one of the most widely usedmarine microalgae in the rearing of finfish and shellfish larvae, is masscultured frequently in outdoor tanks. Under prolonged and repeated culture,severe contamination occurs. Axenic isolation of I.galbanafrom such cultures was best achieved by using a ternary procedure involvingpercoll-gradient centrifugation, treatment with antibiotics, and growth on agarmedium. Protozoa and other algae were removed most effectively by isolation ofI. galbana at the 30–40% density layer on apercoll-gradient. Removal of bacteria was accomplished using a mixture of 5antibiotics (250 μg mL−1 ampicillin, 50μg mL−1 gentamycin, 100 μgmL−1 kanamycin, 500 μgmL−1 neomycin, 50 μgmL−1 streptomycin). Axenic colonies were isolated fromasolid medium prepared from 1% purified agar. The ternary procedure isconsideredapplicable to the isolation of other axenic single-celled microalgae fromheavily contaminated cultures.

Procedures for the axenic isolation of conchocelis and monospores from the red seaweed Porphyra yezoensis

In order to maintain axenic seedstock cultures axenically of thecommercially important red seaweed, Porphyra yezoensis, aprocedure was developed for axenic isolation and culture of conchocelis andmonospores. For axenic isolation of the conchocelis, contaminated microalgaewere most effectively removed by filtering contaminated samples through a100-μm mesh after sonication. Removal of bacteria and otheralgaewas accomplished using a mixture of 5 agents (0.02% chitosan, 100 μgml−1 GeO2, 10 μgml−1 ampicillin, 40 μgml−1 kanamycin and 200 μgml−1 streptomycin). Axenic single colonies wereisolatedfrom a semi-solid medium prepared from 1% transfer gel. After collectingmonospores from the 40–50% density layer on a percoll-gradient, removalofbacteria and fungi from the monospores was accomplished using a mixture of 5antibiotics (3.5 μg ml−1 nystatin, 2 mgml−1 ampicillin, 400 μgml−1 kanamycin, 50 μgml−1 neomycin and 800 μgml−1 streptomycin). Axenic single juvenile blades wereisolated from a semi-solid medium prepared from 0.5% transfer gel.

Isolation of antifouling active pyroglutamic acid, triethyl citrate and di-n-octylphthalate from the brown seaweed Ishige okamurae

Three antifouling active compounds of L-pyroglutamic acid (PGA), triethyl citrate (TEC) and di-n-octylphthalate (DNOP) were isolated from the brown seaweed Ishige okamurae. Approximately 2.8 mg PGA, 1.7 mg TEC, and 2.0 mg DNOP were isolated from 600 g of I. okamurae powder. The concentrations of PGA, TEC, and DNOP required to cause foot repulsion in 50% of mussels (RD50) were 9, 26, and 0.08 mM, respectively. The PGA, TEC, and DNOP concentrations required to inhibit 50% attachment of algal spores (ID50) were 24, 50 and 0.1 mM, respectively. These compounds showed stable antifouling activities against mussel and algal spore attachment.

A methoxylated fatty acid isolated from the brown seaweed Ishige okamurae inhibits bacterial phospholipase A2.

A methoxylated fatty acid that inhibits phospholipase A2 (PLA2; EC 3.1.1.4) was purified from the brown seaweed Ishige okamurae. Approximately 8.1 mg of the inhibitory compound, 7‐methoxy‐9‐methylhexadeca‐4,8‐dienoic acid, was isolated from 1 kg of I. okamurae powder. Recombinant PLA2 derived from the pathogenic bacterium Vibrio mimicus was used as the target enzyme. The methoxylated fatty acid compound competitively inhibited PLA2 with a Ki value of 3.9 µg/mL. The concentrations required for 50% inhibition of PLA2, oedema and erythema were 1.0 µg/mL, 3.6 mg/mL and 4.6 mg/mL, respectively. The compound strongly inhibited PLA2 activity in vitro and had potent antiinflammatory activity in vivo. Copyright

Anti-Edema Effects of Brown Seaweed (Undaria pinnatifida) Extract on Phorbol 12-Myristate 13-Acetate-Induced Mouse Ear Inflammation

The brown seaweed Undaria pinnatifida (Harvey) Suringar is used in traditional medicine to treat fever, urination problems, lumps and swelling, and as a dietary supplement for post-childbirth women. We examined the anti-inflammatory activities of the seaweed. The methanol extract of the seaweed was active against mouse ear edema induced by phorbol myristate acetate (PMA), with an IC(50) of 10.3 mg/ml. The extract reduced the edema to a half-maximal level when applied at the concentration of 40 mg/ml within 3 hours before or 2 hours after application of PMA. Extract taken from the blade section of the seaweed demonstrated the highest activity. The Northern form of U. pinnatifida was more active than the Southern form. In the analgesic test, the methanol extract suppressed the acetic acid-induced writhing response, with an IC(50) of 0.48 g/kg body weight. The extract also demonstrated antipyretic activity in yeast-induced hyperthermic mice. Activity-related constituents were arachidonic, eicosapentaenoic, and stearidonic acids.

Induced changes in the proteomic profile of the phaeophyte Saccharina japonica upon colonization by the bryozoan Membranipora membranacea

The lacy crust bryozoan Membranipora membranacea frequently colonizes the late harvested blades of aquacultured Saccharina japonica. From proteomic profiles of S. japonica, 145 and 91 protein spots were detected from colonized and healthy tissues, respectively. Among them, 69 and 32 spots were significantly up- and downregulated, respectively, in expression level upon colonization. In M. membranacea colonized tissue, tripartite motif protein 2-like, microcompartments protein, carboxysome peptide shell peptide, trypsin precursor-like, transmembrane protein, two-component response regulator PilR, spermine/spermidine synthase, vanadium-dependent bromoperoxidase, peptide chain release factor 1, interaptin, 50S ribosomal protein L1P, plus agglutinin and leucine-rich repeat protein were upregulated, whereas protoporphyrinogen oxidase, PIH1 domain-containing protein 2, GTPase-activating protein alpha, cytoplasmic threonyl-tRNA synthetase, flavanone 3-hydroxylase, and eukaryotic translation initiation factor 3 proteins were downregulated. Moreover, DEAD/DEAH box helicase, glutamyl-tRNA reductase, and chaperone DnaJ protein were newly expressed in the colonized tissue. Most of the up- and downregulated proteins are known to be related to stress control, defense mechanisms, signal transduction, photosynthesis, protein metabolism, and the cytoskeleton.

Viability assay of coralline algae using triphenyltetrazolium chloride

Seaweed flora has been disappearing on rockyareas of the ocean. Meanwhile, crustose corallinealgae, which are non-articulated calcareous algae,are growing and covering these rock surfaces withpink- or white-colored crusts. This phenomenon isgenerally called algal whitening. It is now recog-nized as a natural hazard adversely affectingmarine ecosystems and damaging commercialfishing areas.

Effects of Calcification Inhibitors on the Viability of the Coralline Algae Lithophyllum yessoense and Corallina pilulifera

Coralline algae, the algal whitening phenomenon-causing seaweeds, are characterized by calcareous deposits in the cell wall. The viability of the coralline algae Lithophyllum yessoense and Corallina pilulifera was quantitated using a triphenyltetrazolium chloride assay and eight calcification inhibitors. Among these inhibitors, ferric citrate showed the strongest inhibition of coralline algae viability. The concentrations of ferric citrate conferring 50% inhibition were 1.7 and 3.8 mM for L. yessoense and C. pilulifera, respectively. Thus, at a specific concentration and in a localized area, ferric citrate may be used to prevent the blooming of coralline algae.

Enhancement of Seaweed Rhizoid and Blade Formations by the Chlorophyte Codium fragile Extract

Living organisms can maintain or extend their territories by producing allelochemicals that influence the growth, survival, and reproduction of other organisms. To identify natural biostimulants of positive allelochemicals, we screened 18 common seaweed extracts for enhancement of rhizoid and blade production in a convenient Porphyra suborbiculata monospore assay. By addition of methanolic extract from the most potent green seaweed, Codium fragile, 100% and 50% enhancement doses reflecting the amount of C. fragile extract required to enhance rhizoid formation (in terms of number of spores with rhizoids per total spores tested) were approximately 100 and 50 μg/ml, respectively, in the P. suborbiculata monospore culture. The C. fragile extract quickly enhanced rhizoid formation, rhizoid numbers per rhizoid-holding spore, rhizoid length, blade formation (in number of spores with blade per total spores tested), and blade length from most monospores at early culture days. The extract enhanced rhizoid formation after 2 days of culture significantly, rhizoid numbers per rhizoid-holding spore after 3 days, rhizoid length after 3 days, blade formation after 2 days, and blade length after 1 day, respectively, from most monospores. The allelochemicals that enhanced favorite seaweed species may be efficacious for new seaweed management technologies, including the development of biostimulant agents based on natural products.