Hiroyuki Noda

The main seaweed foods in Japan

The ancient inhabitants of the Japanese archipelago seem to have eaten seaweeds. In fact, remains of marine algae such as Eisenia and Sargassum are often found mixed with shells and fish bones in relics of aborigines of the Jomon-pattern (BC 300–6000) and Yayoi-pattern eras (BC 300–AD 400) in Japanese prehistory.

Health benefits and nutritional properties of nori

A brief review is presented of the properties of nori relevant to health. The dried alga contains large amounts of protein, ash, vitamins and carbohydrate. The levels of taurine (/>- 1.2%) are notable as this compound aids enterohepatic circulation of bile acid, thus preventing gallstone through controlling blood-cholesterol levels. Relatively high levels of eicosapentanoic acid, choline, inositol and other B-group vitamins are regarded as beneficial to health. The occurrence of porphyosins and betaines that prevent respectively, gastric shay ulcers and lower blood-cholesterol levels are particular interest. A sulfated galactan, similar to agar, occurs in relatively large quantities; this is a water-soluble dietary fiber that has important functional activities such as an antiblood coagulant, antihypercholesterolemia and shows antitumor activity. Minerals which occur at relatively high levels in nori include Zn, Cu, Mn and Se.It is concluded that nori is a valuable health food in human diets.

Antitumor activity of marine algae

Powdered tissue from 46 species of air-dried marine algae (four green, 21 brown and 21 red algae) were screened for antitumor activity. Significant activity against Ehrlich carcinoma was found in the brown algae Scytosiphon lomentaria (69.8% inhibition), Lessonia nigrescens (60.0%), Laminaria japonica (57.6%), Sargassum ringgoldianum (46.5%), the red algae Porphyra yezoensis (53.2%) and Eucheuma gelatinae (52.1%) and the green alga Enteromorpha prolifera (51.7%). Five brown and four red algae showed appreciable antitumor activity against Meth-A fibrosarcoma. To identify specific molecules with antitumor activity, 15 kinds of polysaccharide preparations of seaweed origin and 24 kinds of lipid fractions extracted from various seaweeds were tested. Appreciable inhibition of Ehrlich carcinoma was found for fucoidan preparations from Undaria pinnatifida and Sargassum ringgoldianum, for carrageenans and for porphyran. Several glycolipid and phospholipid fractions from brown and red algae were effective against Meth-A fibrosarcoma.

Role of free d- and l-alanine in the Japanese mitten crab Eriocheir japonicus to intracellular osmoregulation during downstream spawning migration

Abstract Changes of d - and l -alanine and other osmolytes were examined in the tissues and hemolymph of the Japanese mitten crab Eriocheir japonicus captured during the maturation in the river and during the course of spawning migration downstream. Only d - and l -alanine and inorganic ions increased significantly in muscle during the maturation in freshwater from July to October and during downstream migration to estuaries in October. Inorganic ions in muscle was the highest in estuaries. In the crabs captured in the sea, glycine and d - and l -alanine were largely elevated in place of the inorganic ions declined. No other free amino acid increased in the muscle of the sea specimens. In hemolymph, total amino acids comprised only 4-10% of total osmolytes and decreased with maturation and during migration. Hemolymph inorganic ions were the highest also in estuaries. These data suggest that, in addition to a role as osmolyte, d - and l- alanine in the tissues of this strong hyperosmoregulator play an important role in the adjustment of salinity tolerance prior to and during downstream migration toward the sea.

Immunological detection of the fungal parasite, Pythium sp.; the causative organism of red rot disease in Porphyra yezoensis

The red rot disease of Porphyra yezoensis Ueda (Rhodophyta) is caused by a parasitic fungus, Pythium sp. To facilitate the detection of this pathogen in infected thalli of P. yezoensis, polyclonal and monoclonal antibodies were prepared. Antibodies were raised against antigen prepared from an isolate of fungal hyphae obtained from red-rot infected thallus of P. yezoensis from Aichi Prefecture. Polyclonal antibody was obtained from the antisera of immunized rabbits. Monoclonal antibody was obtained from the culture supernatant of a hybridoma which had been established by cell fusion between a myeloma cell line and spleen cells of immunized mice. Hyphae were detected by means of indirect fluorescent antibody technique. Titers of polyclonal antibodies obtained were too low to recognize fungal hyphae that had penetrated the thalli of P. yezoensis; however, monoclonal antibody was useful for the detection of fungi that had penetrated algal thalli. The monoclonal antibody was specific for the Pythium sp. from red-rot infected thalli of P. yezoensis from Saga (western Japan) and from Aichi Prefectures (central Japan), but was ineffective for infections from Miyagi Prefecture (northern Japan). It is evident, therefore, that Pythium sp. can give rise to immunologically distinct groups of red rot disease. Based on chemical and enzymatic treatments, the antigenic determinant appeared to localize on the sugar chains of glycoconjugates or the polysaccharides of the hyphal cell wall.

Natural occurrence of denatured phycoerythrin during Porphyra cultivation

Dried Nori (Porphyra spp.) normally turns greenish when toasted and this color usually remains for many days when moistened with vinegar in the Japanese food ‘Sushi’. However, for some lots of toasted Nori, this color changes to an undesirable reddish-brown one within a few hours in vinegar. A clear difference was noticed by spectrophotometry between the abnormally and normally colored toasted Nori. The former exhibited absorption maxima at around 490 and 530–600 nm while these were absent in the spectrum of the latter. The responsible pigment for the abnormal coloration was purified by ammonium sulfate fractionation and preparative flat-bed isoelectric focusing. On the basis of pI, molecular weight and the visible absorption, fluorescence and circular dichroism spectra, the pigment was identified as monomeric phycoerythrin. Dried Nori contained three times as much monomer as hexamer. From field cultivation tests, dried Nori produced large amounts of monomeric phycoerythrin when the fronds on frozen nursery-nets were damaged.