The Immunomodulating Effect of Phlorotannins from a Brown Alga, Eisenia nipponica, on Mice Stimulated with Ovalbumin through T Cell Regulation.

The immunomodulating effect of phlorotannin was investigated in mice stimulated by ovalbumin. When analyzing the main components of phlorotannin concentrate (PTC) from Eisenia nipponica, seven phlorotannins [eckol, 6,6'-bieckol, 6,8'-bieckol, 8,8'-bieckol, dieckol, phlorofucofuroeckol (PFF)-A, and PFF-B] were detected. These phlorotannins accounted for approximately 80% of PTC. Oral administration of PTC to mice daily for 21 days reduced serum immunoglobulin E (IgE) and total IgG1 levels attributable to Th2 cells. The production of splenic cytokines [interleukin (IL)-10 and transforming growth factor-ß1] and Treg cell-mediated expression of forkhead box protein P3 mRNA were significantly increased whereas the production of inflammatory cytokines (interferon-γ, IL-4, IL-5, and IL-17) by Th1, Th2, and Th17 cells was markedly suppressed. IL-21 production and basic leucine zipper ATF-like transcription factor mRNA expression attributable to follicular helper T (Tfh) cells were also suppressed. Flow cytometric analyses demonstrated increased number of Treg cells despite a decrease in the total T cell population. An increase in total B cells was also observed by the flow cytometric analyses in addition to increases in IL-10 production, which activates B cells. In contrast, the significantly suppressed production of inflammatory cytokines and moderate increase in Treg cell subpopulation indicated a direct impact of PTC on inflammatory lymphocytes (Th1, Th2, Th17, and Tfh). Thus, PTC may exert antiallergic effects by immunomodulation of T cells and inactivation of inflammatory lymphocyte.

Trivalent Iron Is Responsible for the Yellow Color Development in the Nacre of Akoya Pearl Oyster Shells.

The gold and cream colors of cultured Akoya pearls, as well as natural yellow nacre of pearl oyster shells, are thought to arise from intrinsic yellow pigments. While the isolation of the yellow pigments has been attempted using a large amount of gold pearls, the substance concerned is still unknown. We report here on the purification and characterization of yellow pigments from the nacre of Akoya pearl oyster shells. Two yellow components, YC1 and YC2, were isolated from the HCl-methanol (HCl-MeOH) extract from nacreous organic matrices obtained by decalcification of the shells with ethylenediaminetetraacetic acid (EDTA). Energy-dispersive X-ray and infrared spectroscopy analyses suggested that YC1 and YC2 precipitated under basic conditions are composed of Fe-containing inorganic and polyamide-containing organic compounds, respectively. YC1 solubilized under acidic conditions exhibited positive reactions to KSCN and K4[Fe(CN)6] reagents, showing the same ultraviolet-visible absorption spectrum as those of Fe(III)-containing compounds. In addition, X-ray absorption fine structure analysis supported the compound in the form of Fe(III). The total amount of Fe was approximately 2.6 times higher in the yellow than white nacre, and most Fe was fractionated into the EDTA-decalcifying and HCl-MeOH extracts. These results suggest that Fe(III) coordinated to EDTA-soluble and insoluble matrix compounds are mainly associated with yellow color development not only in the Akoya pearl oyster shells but also in the cultured Akoya pearls.

Orally Administered Phlorotannins from Eisenia arborea Suppress Chemical Mediator Release and Cyclooxygenase-2 Signaling to Alleviate Mouse Ear Swelling.

Phlorotannin is the collective term for polyphenols derived from brown algae belonging to the genera Ascopyllum, Ecklonia, Eisenia, Fucus and Sargassum etc. Since the incidence of allergies is currently increasing in the world, there is a focus on phlorotannins having anti-allergic and anti-inflammatory effects. In this study, six purified phlorotannins (eckol; 6,6'-bieckol; 6,8'-bieckol; 8,8'-bieckol; phlorofucofuroeckol (PFF)-A and PFF-B) from Eisenia arborea, orally administered to mice, were examined for their suppression effects on ear swelling. In considering the suppression, we also examined whether the phlorotannins suppressed release of chemical mediators (histamine, leukotriene B4 and prostaglandin E2), and mRNA expression and/or the activity of cyclooxygenase-2 (COX-2), using RBL-2H3 cells, a cultured mast cell model. Results showed that the phlorotnannins exhibited suppression effects in all experiments, with 6,8'-bieckol, 8,8'-bieckol and PFF-A showing the strongest of these effects. In conclusion, orally administered phlorotannins suppress mouse ear swelling, and this mechanism apparently involves suppression of chemical mediator release and COX-2 mRNA expression or activity. This is the first report of the anti-allergic effects of the orally administered purified phlorotannins in vivo. Phlorotannins show potential for use in functional foods or drugs.

Comparison of Two Pearl Sacs Formed in the Same Recipient Oyster with Different Genetic Background Involved in Yellow Pigmentation in Pinctada fucata.

Color is one of the most important factors determining the commercial value of pearls. Pinctada fucata is a well-known pearl oyster producing high-quality Akoya pearls. Phenotypic variation in amount of yellow pigmentation produces white and yellowish pearls. It has been reported that polymorphism of yellow pigmentation of Akoya pearls is genetically regulated, but the responsible gene(s) has remained unknown. Here, we prepared pearl sac pairs formed in the same recipient oyster but coming from donor oysters that differ in their color. These two pearl sacs produced pearls with different yellowness even in the same recipient oyster. Yellow tone of produced pearls was consistent with shell nacre color of donor oysters from which mantle grafts were prepared, indicating that donor oysters strongly contribute to the yellow coloration of Akoya pearls. We also conducted comparative RNA-seq analysis and retrieved several candidate genes involved in the pearl coloration. Whole gene expression patterns of pair sacs were not grouped by pearl color they produced, but grouped by recipient oysters in which they were grown, suggesting that the number of genes involved in the yellow coloration is quite small, and that recipient oyster affects gene expression of the majority of genes in the pearl sac.

Isolation and functional characterization of an ammonium transporter gene, PyAMT1, related to nitrogen assimilation in the marine macroalga Pyropia yezoensis (Rhodophyta).

Ammonium and nitrate are the primary nitrogen sources in natural environments, and are essential for growth and development in photosynthetic eukaryotes. In this study, we report on the isolation and characterization of an ammonium transporter gene (PyAMT1) which performs a key function in nitrogen (N) metabolism of Pyropia yezoensis thalli. The predicted length of PyAMT1 was 483 amino acids (AAs). The AA sequence included 11 putative transmembrane domains and showed approximately 33-44% identity to algal and plant AMT1 AA sequences. Functional complementation in an AMT-defective yeast mutant indicated that PyAMT1 mediated ammonium transport across the plasma membrane. Expression analysis showed that the PyAMT1 mRNA level was strongly induced by N-deficiency, and was more highly suppressed by resupply of inorganic-N than organic-N. These results suggest that PyAMT1 plays important roles in the ammonium transport system, and is highly regulated in response to external/internal N-status.

Isolation and characterization of a SEPALLATA-like gene, ZjMADS1, from marine angiosperm Zostera japonica.

In flowering plants, floral homeotic MADS-box genes, which constitute a large multigene family, play important roles in the specification of floral organs as defined by the ABCDE model. In this study, a MADS-box gene, ZjMADS1, was isolated and characterized from the marine angiosperm Zostera japonica. The predicted length of the ZjMADS1 protein was 246 amino acids (AA), and the AA sequence was most similar to those of the SEPALLATA (SEP) subfamily, corresponding to E-function genes. Southern blot analysis suggested the presence of two SEP3-like genes in the Z. japonica genome. ZjMADS1 mRNA levels were extremely high in the spadices, regardless of the developmental stage, compared to other organs from the reproductive and vegetative shoots. These results suggest that the ZjMADS1 gene may be involved in spadix development in Z. japonica and act as an E-function gene in floral organ development in marine angiosperms.

Isolation and characterization of a cDNA encoding a heat shock protein 70 from a sterile mutant of Ulva pertusa (Ulvales, Chlorophyta).

Synthesis and accumulation of molecular chaperones are universal responses found in all cellular organisms when exposed to a variety of unfavorable conditions. Heat shock protein 70 (Hsp70), which is one of the major classes of molecular chaperones, plays a particularly important role in cellular stress responses, and the Hsp70 system is the most intensely studied in higher plants and algae. Therefore, we isolated and characterized a cDNA clone encoding Hsp70 from a sterile strain of Ulva pertusa (Ulvales, Chlorophyta). The sterile U. pertusa Hsp70 (UpHsp70) cDNA consisted of 2,272 nucleotides and had an open reading frame encoding a polypeptide of 663 amino acid (AA) residues with a molecular mass of 71.7 kDa. Amino acid alignment and phylogenetic analysis of Hsp70s from other organisms showed that UpHsp70 was more similar to cytoplasmic Hsp70s from green algae and higher plants (> or =75%) than to those from other algae and microorganisms. Southern blot analysis indicated that the sterile U. pertusa genome had at least four cytoplasmic Hsp70-encoding genes. UpHsp70 mRNA levels were significantly affected by diurnal changes, rapidly increased by high-temperature stress, and gradually increased by exposure to copper, cadmium, and lead. These results suggest that UpHsp70 plays particularly important roles in adaptation to high-temperature conditions and diurnal changes, and is potentially involved in tolerance to heavy metal toxicity.

Isolation and characterization of a single-copy actin gene from a sterile mutant of Ulva pertusa (Ulvales, Chlorophyta).

We constructed a cDNA library from sterile Ulva pertusa (Ulvales, Chlorophyta), and isolated and characterized a full-length cDNA clone encoding actin. The actin (ACT) cDNA consisted of 1487 nucleotides (nt) and had an open reading frame (ORF) encoding a polypeptide of 377 amino acid (AA) residues. The ACT gene had one intron in the 5'-untranslated region and three introns in the coding region. Transcription started 26 nt downstream of the putative TATA box. A potential polyadenylation signal, TGTAG, was located 100 nt downstream of the terminator codon, TAG. Amino acid alignment with actins from various algae and land plants showed that sterile U. pertusa actin was more similar to actins from Chlorophyta, Phaeophyta, Euglenophyta, and higher plants (over 76.9%) than to actins from Rhodophyta. Southern blot analysis indicated that the sterile U. pertusa genome has only a single actin-encoding gene. Thalli grown on a 12D/12L photoperiod increased in surface area some two-fold over 24 h regardless of the nutritional conditions. The growth rate of thalli during the light period was significantly higher than that during the dark period. Northern hybridization indicated that the expression of actin mRNA was induced and repressed by the light and dark treatments, respectively. These results suggest that the U. pertusa cell division cycle has a periodicity of 24 h and that the ACT gene is highly transcribed during cell growth and development in the light period.

Differential scanning calorimetry and circular dichroism spectrometry of walleye pollack myosin and light meromyosin.

The thermodynamic properties of myosin and its C-terminal fragment, light meromyosin (LMM), from walleye pollack, a typical cold-water fish efficiently utilized on an industrial scale, were analyzed by using differential scanning calorimetry (DSC) and circular dichroism (CD) spectrometry. Recombinant walleye pollack LMM expressed in Escherichia coli was also subjected to DSC and CD measurements for reference. The two proteins prepared from frozen surimi showed three endothermic peaks, the transition temperatures (T(m)) of which were quite similar, although overall DSC patterns differed considerably from one another. Their alpha-helical contents determined by CD were low compared to values reported before for other species. On the other hand, recombinant LMM gave four endothermic peaks at 27.4, 30.8, 36.5, and 43.4 degrees C in DSC and showed an alpha-helical content of approximately 80%. The peak at 27.4 degrees C could not be observed in walleye pollack LMM prepared from frozen surimi and thus was possibly attributed to its C terminus, because this extreme C-terminal region is supposedly truncated during preparation of LMM by tryptic digestion.