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The effects of temperature and photoperiod on the growth rate and maturation rate of the parthenogenetic strain of the brown alga Petalonia binghamiae were examined. The relative growth rate of the germlings grown from gametes was highest at 25 °C and decreased at 30 °C. There was no significant difference in the relative growth rate under long-day and medium-day conditions, but it was lower under short-day conditions. The germlings formed blades at 10–15 °C, but not at 25 °C. The blade formation rates of microthalli derived from the stock culture reached > 70% at each photoperiod, while the germlings grown from gametes did not form blades under short-day conditions. The relative growth rate of the blades was highest at 15 °C. All blades matured at 10–20 °C, but not at 25 °C. The use of the parthenogenetic strain of P. binghamiae will enable simplification of the cultivation method of this species.

Three Gram-negative, aerobic, halophilic bacterial strains, SCM2-10 T , SCM-4, and 14C-6, were isolated from the algal medium of the red alga Pyropia yezoensis (previously classified as Porphyra yezoensis ) grown in laboratory experiments. Phylogenetic analysis based on 16S rRNA gene sequences revealed that the organisms with high similarities to the three isolates are Sulfitobacter geojensis MM-124 T (98.7 %), Sulfitobacter noctilucicola NB-77 T (98.7 %), Sulfitobacter noctilucae NB-68 T (98.6 %), Sulfitobacter mediterraneus CH-B427 T (97.6 %), and Sulfitobacter porphyrae SCM-1 T (97.6 %), and that the three isolates belong to the genus Sulfitobacter , within the class Alphaproteobacteria . The DNA G+C contents of the three isolates were found to be in the range of 56.5–57.1 mol%. DNA–DNA hybridization experiments demonstrated that the genomic relatedness between strain SCM2-10 T and type strains of other Sulfitobacter species was in the range of 6.2–27.1 %. The predominant respiratory quinone of the three isolates was identified as ubiquinone-10. The dominant polar lipids in the three isolates were found to be phosphatidylcholine, phosphatidylethanolamine, phosphatidylglycerol, and an unidentified amino lipid. The major fatty acid in the three isolates is C 18:1 ω 7 c . Strain SCM2-10 T demonstrated unique phenotypic characteristics, which differed from those of type strains of other Sulfitobacter species. Based on the phylogenetic, genetic, phenotypic, and chemotaxonomic data, we propose a novel species of the genus Sulfitobacter , which we named as Sulfitobacter pacificus sp. nov. The type strain of this species is strain SCM2-10 T (=LMG 27113 T  = NBRC 109915 T ).

This study investigated the anti-allergic effect of a diethyl ether fraction from dried Sargassum fusiforme . In vivo experiments showed that percutaneous administration of this fraction suppressed mouse ear swelling induced by three types of sensitizers (arachidonic acid, 12- O -tetradecanoylphorbol-13-acetate and oxazolone). At a dose of 0.1 mg/mouse, the suppression ratios were from 47 to 61 %. Oral administration of the fraction also suppressed mouse ear swelling. At a dose of 1 mg/mouse, the suppression ratios were from 69 to 92 % which were comparable to those obtained by the typical natural inhibitor, epigallocatechin gallate (EGCG). In vitro experiments were performed to elucidate the inhibitory effects of the fraction on the enzymatic activities (phospholipase A 2 , cyclooxygenase-2, lipoxygenase and hyaluronidase) involved in inflammation and degranulation in rat basophilic leukemia (RBL)-2H3 cells to understand the mechanism that underlies the suppression of mouse ear swelling. Similar to EGCG, the fraction inhibited the enzymatic activities tested and suppressed degranulation in RBL cells in a dose-dependent manner. Therefore, the active components present in this S . fusiforme fraction achieve the anti-inflammatory effects by inhibiting the enzymatic activities and degranulation in the ear of mice. Thus, S . fusiforme and its diethyl ether fraction could be useful ingredients in functional foods.

The optimal water temperature in seed germination and the upper critical water temperature in seedling growth were determined for Zostera marina collected from Ise Bay, Japan. The relationship between the seed germination rates and seed storage period (0, 30 and 60 days at 0°C) was also examined. The optimal water temperature for seed germination was in the range from 10 to 15°C regardless of the storage periods, in which germination rates ranged from 35 to 57%. Seedlings grown from seed up to 10 cm in total length were cultured for 1 week under various water temperatures to measure their relative growth rates. The optimal water temperature in growth was in the range from 20 to 25°C; relative growth rates ranged from 2.0 to 2.6%. Seedlings could survive up to a water temperature of 28°C, but most seedlings withered at 29 or 30°C. The optimal water temperatures for seed germination and seedling growth were related to the seasonal changes of water temperature at the sampling site. Although seedlings were rarely observed in the field in summer, they can grow at temperatures as high as 28°C. Therefore, Z. marina may extend its distribution as far as where the summer water temperature is lower than 28°C.

In order to distinguish 18 Porphyra and Pyropia species, the present study employed polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) analysis using mitochondrial DNA related to the ATP synthase F0 subunit 6 (ATP6) gene and partial mitochondrial DNA including trnC, rps11, sdh3, trnG, trnN, trnP, and rns. The two primer sets on the mitochondrial DNA used in this study were able to amplify single fragments with PCR in 16 Japanese and 2 non-Japanese Porphyra and Pyropia species. Lengths of partial mitochondrial DNA related to ATP6 gene and trnC–rns ranged from 664 bp (Py. dentata and Py. haitanensis) to 677 bp (Py. lacerata and Py. kurogii) and from 1,292 bp (Py. seriata) to 1,343 bp (Py. kurogii and Py. moriensis), respectively. All 18 species were successfully distinguished using a combination of five restriction enzymes (TaqI, SspI, AciI, Cfr13I, and AluI). It was therefore concluded that PCR-RFLP analysis is a valuable tool for discrimination of wild strains of Porphyra and Pyropia species for potential use in mariculture.

Photosynthetic activity of Zostera japonica seedlings was measured using a gas volumeter at 0 and 6 days in culture under eight light (0-800 micromol photons/square m/s) and ten water temperature conditions (5-35degC). Seedlings from Ago Bay, Mie Prefecture were cultured in incubators accurately controlled at each test temperature for 1 week. After 1 week, maximum gross photosynthesis (Psub(maxg)) appeared at 29degC and most seedlings cultured at 30-35degC bleached and withered. At the same time, the light compensation point (Isub(c)) increased only at 30degC during the culture period. As a result, the upper critical water temperature for survival was 29degC in Z. japonica seedlings, which agrees well with that for the southern boundary of Z. japonica around Japanese coast. It is necessary to monitor this species around this boundary as a bio-indicator for seawater warming.

The optimal water temperature in seed germination and the upper critical water temperature in seedling growth were determined for Zostera japonica collected from Ago Bay, Japan. The relationship between the seed germination rates and seed storage period (0, 30, and 60 days) at 0degC was also examined. The optimal water temperature in seed germination was in the range 15-20degC regardless of the storage period, in which germination rates were up to 14%. Seedlings, grown from seeds up to 10 cm in total length, were cultured for 1 week at various water temperatures to measure their relative growth rates. The optimal water temperature in early growth was in the range 20-25degC; relative growth rates ranged from 3.8 to 4.2%. Seedlings could survive up to a water temperature of 29degC, but most seedlings withered at 30 or 35degC. The optimal water temperatures for seed germination and seedling growth were related to the seasonal changes of water temperature in the sampling site. Although seedlings were hardly observed in Ago Bay in summer, Z. japonica might extend its distribution as far as where the summer water temperature is lower than 29degC.

Photosynthesis and respiration rates were measured on 10 cm tall seedlings of Z. japonica at various temperatures and photosynthetic photon flux densities (PPFDs), and the daily compensation points in each season were estimated with a mathematical model based on photosynthetic properties and diurnal changes in solar irradiances. The seedlings were grown from seeds collected at Tategami-ura, Ago Bay, Mie Prefecture, Japan, and cultured for 1 week under the examined temperatures of 10-25degC. The estimated daily compensation points of Z. japonica ranged from 9.3 to 13.6% of the surface irradiance. The total PPFDs in daytime ranged from 3.8 to 5.3 mol photons/square m/day. The theoretical depth limits were calculated by the Beer-Lambert law concerning the relative light intensities of the sea surface and the extinction coefficient. The estimated lowest limit of Z. japonica agreed well with the lowest depth (7 m) previously reported. Therefore, the mathematical model in this study can be used to estimate the production and critical growing depth of Z. japonica. Differences in light requirements seem to be one of the reasons for the shallower habitats of Z. japonica in comparison with Z. marina.

Bacteria and marine macroalgae form close associations, while various bacteria affect the morphogenesis and growth of macroalgae. Hyphomonas strains exhibit normal morphogenetic activity in protoplasts of the red alga Pyropia yezoensis (nori). However, the effects of the bacteria on the growth of Pyropia from protoplast cells to regenerated thalli remain unknown. Here, we assessed the growth of P. yezoensis and Pyropia tenera using combined cultures of three Hyphomonas strains (LNM10-16, SCM-2, and LNM-9) and three algal media (artificial seawater with vitamins, artificial seawater, and natural seawater) over 7 weeks. Third week after culture, the three Hyphomonas strains showed almost similar levels of normal growth activity for both Pyropia species. However, at 7 weeks, significant differences were observed among the three Hyphomonas strains in terms of length, length-to-width ratio, and normal morphology of Pyropia thalli. LNM10-16 significantly promoted the thalli length and length-to-width ratios of both Pyropia species in artificial seawater without vitamins and natural seawater, compared with the other two Hyphomonas strains. P. yezoensis cultured in artificial seawater with vitamins showed a much higher demand for LNM10-16 in development of the thalli length than P. tenera . These results may be explained by differences in the growth activities of Hyphomonas strains and the nutrient requirements of Pyropia species. Furthermore, the bacteria were more specifically attached to the rhizoid surfaces of both species. This study is the first to reveal that Hyphomonas strains affect the growth of Pyropia species by attaching to their rhizoids.