A physiological or an ecological investigation sometimes suggests potentially cryptic species. Taxonomic study such as morphological and molecular analysis are required to verify the independency of the cryptic species. Construction of phylogenetic tree is an essential part of the molecular analysis. However, the opportunity is limited for applied phycologists to learn the principal and procedure of the phylogenetic analysis. Therefore, here we summarized the basic knowledge of phylogenetic analyses including 1) construction of molecular dataset, 2) characters of the currently employed methods, and 3) selection of appropriate method. In the final section, we described the procedure to perform maximum likelihood tree using a software MEGA.

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A wide range of tip-growing cells in fungi and plants display polarized cell growth, which is an essential cellular process for the form and function of individual cells. Vesicles containing new cell wall components and membranes are secreted into the apical dome, and, coupled with turgor pressure-driven cell, this restricts growth to this limited zone. Understanding the regulatory mechanisms underlying tip growth in land plants has been advanced through the use of three main cell types: moss protonemata, root hairs and pollen tubes of seed plants. The relationship between the signal transduction, ion gradient and cytoskeleton, have been a subject of much interest. In some species of algae that form filamentous cells, cellular processes in tip growth have also been investigated, but their regulatory mechanisms remain unclear. In the macro red alga Neopyropia yezoensis, for which genome information has recently been released, the conchocelis apical cell exhibits tip growth and form the filamentous structure. We established a live-imaging system with high-resolution microscopy to analyze tip growth of N. yezoensis conchocelis. This review addresses recent advances in our understanding of plant tip growth, including algae, as well as evolutionary insights from the use of the conchocelis.

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Phycobilisomes (PBSs) are light-harvesting complexes found in cyanobacteria and red algae. These organisms degrade PBS under nitrogen-limited conditions. In cyanobacteria, the small NblA protein plays a key role in this process; it acts as an adaptor protein to promote the interaction of a Clp protease with phycobiliproteins. There is an nblA-like gene (ycf18) the chloroplast genomes of most red algae. Recently additional nblA genes were identified in the nuclear genomes of Porphyra umbilicalis, Pyropia yezoensis, Gracilariopsis chorda, Galdieria sulphuraria, Cyanidioschyzon merolae, and Porphyridium purpureum. However, their function remains unknown. This review focused on two types of NblA in red algae: Ycf18 and NblA. Typically, both contain an intact NblA motif, although P. purpureum Ycf18 does not. Ycf18 is composed of approximately 60 amino acids, although five NblAs were predicted to be located in chloroplasts, and to be larger (88 to 227 amino acids) due to disordered regions at the N- and C-terminal ends. Cyanobacterial nblA gene existing as single copy in the genome acts as a homodimer. The occurrence of two nblA genes in these red algae suggested that a heterodimer may play a role in PBS degradation in red algae. This will be discussed from the perspective of the protein structure of NblA.

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On the coast of Japan, ca 3,000 fishing ports are present. The walls of mooring space and breakwater, slipways, bottom and blocks provide substrata for algae to attach, resulting in the formation of macroalgal beds (sometimes including sea grass). These beds have been paid attention to study algal succession, to use as nursery or feed of shellfish and to enlarge such algal beds by researchers in the field of phycology, ecology and coastal engineering. Among the above structures, slipways are the most convenient sites to observe vegetation because of its horizontal development of algal beds, safe accessibility and availability of clear vegetational images in aerial photographs. Macroalgal beds range from intertidal to upper subtidal zones on the slipways; zonation of canopy-forming species or commercial algae including nori and kelp, urchin barrens, or other positive and negative effects by the ambient factors such as sedimentation and waste charge. Our preliminary survey also found additional alteration of vegetation by presence of substructures of slipways including as slip bar, pit, corner, wall, and grooves of blocks. Sustainable, costless and easy monitoring of these beds may help local residents understand the important productive communities on their closest parts of their coasts.

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Umami taste of dried nori and toasted nori mainly correlates to IMP production by AMP deaminase activity in the nori extract during manducation. In this minireview, we summarized enzymatic properties of reported IMP-producing enzymes from various sources, and point out confusion in historical nomenclature for these enzymes in Neopyropia: 5'-AMP deaminase (EC 3.5.4.6) and adenosine-phosphate deaminase (EC 3.5.4.17). We also discuss possible physiological roles of these enzymes in red algae.

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From the records in ruins of ancient Japan, everyone knows Japanese people have been eating seaweed since very early times in history, and it is an important foodstuff for Japanese cuisine. In recent years, due to changes in dietary habits of Japanese people, the incidence of lifestyle-related diseases such as cancer, diabetes, and Alzheimer's disease (AD), has increased. It was assumed that eating seaweed and its processed products could prevent such diseases. In order to verify this assumption, a series of animal experiments were conducted. Several types of seaweed proved to reduce the risk of developing colorectal cancer and breast cancer. Among them, Amanori (Porphyra yezoensis) was found to suppress the carcinogenic rate in intestine and breast remarkably. It was also found that impaired glucose tolerance was improved in Wakame (Undaria pinnatifida) diet with mouse model of type 2 diabetes. Furthermore, in the experiments with transgenic mouse model of AD, these results showed that eating of Wakame can be expected to prevent the effect of onset. In this way, it turned out that seaweed proved to effect on lifestyle-related diseases. On the other hand, seaweed contains iodine, so intermittent intake is recommended for overdose prevention.

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The sexual life cycle in plants generally consists of a haploid gametophyte and a diploid sporophyte, both of which appear reciprocally at temporally different stages via fertilization of gametes to produce sporophytes and meiosis to produce gametophytes. The red seaweeds Bangiales display a heteromorphic sexual life cycle containing a leafy gametophyte (thallus) and a filamentous sporophyte (conchocelis). Unlike other multicellular eukaryotes, the production of gametophytic spores, termed conchospores, in a conchosporangium is not associated with meiosis in Bangiales. To explore this question, we performed transcriptomic profiling of Pyropia yezoensis gametophytes, sporophytes and conchosporangia and identified a knotted-like homeobox gene that is predominately expressed in the conchosporangium and may determine its identity. Further, spore-like single cells isolated from conchosporangia developed directly into thalli. We therefore concluded that gametophytic identity is established in the conchosporangium before release of conchospores without meiosis and proposed a triphasic life cycle in P. yezoensis where apospory is responsible for production of gametophyte generation.

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Because of their sessile nature, intertidal aquatic seaweeds are usually exposed to changes in living conditions as environmental stresses. Thus, acclimation and acquisition of tolerance to these stresses are indispensable for their sustainable survival. We here summarized two topics of our recent studies on physiological strategies of Bangiales for survival under stressful conditions. (1) Life cycle trade-off: Excision of explants from gametophytes of Pyropia yezoensis accelerated release of monospores and carpospores that were generated via the activation of asexual and sexual reproductive processes, respectively. In contrast, heat stress at sub-lethal 25℃ stimulated the production of a callus, from which new gametophytic thalli with a normal shape were generated asexually. Thus, wounding and heat stress differently promote the life cycle trade-off that can reset the timing of reproduction. (2) Stress memory: When Bangia sp. ESS1 was exposed to sub-lethal high temperature 28℃, strong tolerance to lethal high temperature 32℃ was established. Since thermotolerance was maintained after returning to standard growth temperature 15℃ for several days, it was concluded that Bangia sp. ESS1 can acquire memory of heat stress to protect themselves against exposure to lethal high temperature. These findings demonstrate the presence of a variety of distinct survival and growth strategies in Bangiales to cope with different environmental stress conditions.

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Kelp forests are important in coastal ecosystems as primary producers and
habitat for marine organisms. However, recent global warming has been inducing reductions of kelp forests in various parts of the world. This study investigated high-temperature tolerance of a representative kelp forest constituent Eisenia bicyclis collected from southern edge (Itoshima, Fukuoka Prefecture) and central (Tateyama, Chiba Prefecture) population. Adult sporophytes collected from the fields and juvenile sporophytes derived from gametophytes were used for the comparison. The sporophytes were cultivated under different temperature conditions: 20, 22, 24, 26, 28 and 30 ℃. Then, the maximum quantum yield (F_v /F_m) was measured using Imaging-PAM. The adult and juvenile sporophytes from Fukuoka maintained significantly higher F_v /F_m at 30 ℃ than those from Takeyama. This indicates that E. bicyclis from southern population (Fukuoka) has high-temperature tolerance.

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The terrestrial cyanobacterium Nostoc commune accumulated high concentration of radioactive cesium. In this study, we investigated the effect of soil properties on radioactive cesium uptake by N. commune. A cultivation experiment confirmed that N. commune absorbed radioactive cesium from polluted sand, loam, and humus soil respectively. Especially in sand, the concentration factor of radioactive cesium to N. commune was high. Addition of potassium compounds to soil strongly inhibited radioactive cesium accumulation by N. commune. Of the three potassium compounds, KNO₃， KH₂PO₄ and K₂SO₄, investigated, K₂SO₄ had the most prominent inhibitory effect.

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Thallus of the marine red alga Pyropia yezoensis is receiving increased attention as an industrially and economically important species for production of not only the Japanese traditional food, nori, but also high-quality agar polysaccharides. We have already demonstrated that the yield of agar from discolored thalli is higher than that from normal ones; however, the cause of this characteristic is still unclear. To address a reason why discolored P. yezoensis is suitable for agar production, we here compared a stainability between normal and discolored thalli with toluidine blue, which is a basic dye causing metachromasy for acidic polysaccharides, because cell wall of this species contains the sulfated acidic porphyran as a precursor of agar. As results, although porphyran in the cell wall of both materials was dyed in purplish red by metachromasy, intensity and area of staining were considerably higher and wider in discolored thalli. In addition, cells of discolored thalli were severely damaged and destroyed during the process of agar extraction. These findings indicate that both substantial amount and efficient extraction of porphyran are responsible for high yield of agar from discolored P. yezoensis thalli.

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We investigated the relationship between the amount of free amino acids and the salinity conditions in cultivation (10 ‰ or 30 ‰) of two red algal species, Neopyropia tenera (Kjellman) L.-E. Yang & J. Brodie, and Neopyropia yezoensis (Ueda) L.-E. Yang & J. Brodie. The total amount of free amino acids and the level of Alanine of N. tenera were significantly higher than those of N. yezoensis in 30 ‰ seawater. Alanine is known as the most major free amino acid with umami and the sweetness in the genus Neopyropia. This result might be one of reasons why N. tenera tastes sweeter than N. yezoensis. In addition, it was shown that in each species the total amount of free amino acids and the level of Alanine in 30 ‰ seawater were significantly higher than those in 10 ‰ seawater.

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In the case of no correlation between the agar gel strength and contents of sulfate ester and 3,6-anhydro-L-galactose, or the molecular weight, effect of molecular weight distribution was examined to gel forming ability. Low molecular weight agar (M_w= 0.26×10⁵) was added to four agars with different molecular weight and molecular weight distribution. In three agars (M_w = 0.82, 1.03, 1.92×10⁵) containing large amount of low molecular weight fraction and showing high gel strength, the gel strength and the gel fracture energy by adding low molecular weight agar of 5 wt％ were about 15％ and 50％ reduction, respectively. On the other hand, in an agar (M_w = 1.90×10⁵) containing small amount of low molecular weight fraction and showing low gel strength, the gel strength and the gel fracture energy were about 10% reduction by adding low molecular weight agar of 16 wt％. Therefore, the reinforcement effect to gel strength by small molecule was estimated. If in two agars with the same average molecular weight, an agar containing large amount of both high and low molecular weight fractions was expected to show high gel forming ability.

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In the present study, we summarized the results of Undaria pinnatifida seedling production using a new method by application of free-living gametophytes conducted at seedling production sites in Tokushima Prefecture from 2011 to 2019.
　Seedling production by application of free-living gametophytes was started at a production site by a fisherman in 2011. Subsequently, the number of production sites and fishermen has progressively increased, and 37 fishermen in 2019 worked on the new method at 28 production sites. In addition, the length of the applied seed strings was 450 m in 2011, but in 2019, it reached 35,820 m. The total length of applied seed strings we investigated from 2013 to 2019 was 53,735 m, of which 42,251 m (78.6 ％) successfully produced seedlings and the results were stable at about 80 ％ every year. In contrast, the conventional seedling production using zoospores was not stable, ranging 0-60 ％ in the seven years, and was consistently less than the results of the new method every year.
　Seedling production of U. pinnatifida using free-living gametophytes has remained at an experimental scale for a long time, however now the seedling production method by application of free-living gametophytes has been completely realized to enable commercialization at the production sites.

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Using genome-wide SNP data obtained from high-throughput techniques based on a double digest restriction site-associated DNA sequencing (ddRAD-seq), we elucidated the migration history and genetic diversity of the ecologically important red seaweed Gelidium elegans Kuätzing in Japan. STRUCTURE and NeighborNet analyses showed a clear genetic differentiation among three geographic regions: Sea of Japan and Pacific coast of Tohoku region (POP1), Mie and Kochi (POP2), and Shizuoka and Chiba (POP3). Approximate Bayesian Computation (ABC) analysis indicated that POP1 diverged first, followed by a separation of remaining populations into POP2 and POP3. Low genetic diversity was detected in POP1, whereas high genetic diversity was detected in POP2 and POP3.

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Re-establishment process of Ecklonia kurome stand on denuded natural rocky substrata was observed for 4 years off Kata-Shima, western Seto Inland Sea. In the natural E. kurome stand at two sites of Kata-Shima (Tokkuri-bana and Hagi-bana), all macroalgae except for crustose algae within two 1×1 m permanent quadrats in each site were removed in November 2012. In February 2013, recruits of E. kurome (the 2013 year class) were observed at densities of 50-96 inds. m^-2 in the quadrats. The 2013 year class grew to adult and formed dominant canopies in 2014. In November 2014, 2 years after the denuding, mean densities (15-18 inds. m^-2)and stipe length of the 2013 year class reached a similar level of the ambient natural stand except those in one quadrat in which the density (50 inds. m^-2) was higher and mean stipe length was larger than those in other quadrats. This difference of survival and growth indicated that some environmental conditions could vary even between the quadrats in close proximity and affect the development of local stands. After 4 years from the denuding, approximately 10 ％ individuals of the 2013 year class remained at Hagi-bana. This result indicates the maximum lifespan of E. kurome in this area might be at least 5 years.

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Diving surveys using quadrats were conducted near the estuary of the Shiribetsu River in Isoya, Suttsu, southwestern Hokkaido, Japan from 2012 to 2018. Disjunctive distribution of the kelp Saccharina japonica var. ochotensis was confirmed and maintained a rich kelp forest with a high biomass. Large biennial sporophytes of this species occurred in deeper rocky areas, 5-10 m, and smaller annual sporophytes were observed in shallower areas at 0-5 m in depth. Growth of test diameter and gonads of two sea urchin species Mesocentrotus nudus and Strongylocentrotus intermedius were elevated compared to Isoyake area and factors related to this enhancement are discussed.

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The artificial reefs (ARs) deployed on a sandy-muddy bottom at depths of 10 to 16 m in Beppu Bay, southern Japan were investigated using ROV (Remotely Operated Vehicle) and scuba diving from 2008 to 2017. The ARs were made of cubic concrete blocks overlaid by two porous panels consisting of seashells on top side. Young thalli of Sargassum sp. appeared on the panels in the first year. The dominant macroalgal communities changed from Sargassum sp. to Ecklonia kurome after several years. Macroalgae were more abundant on the porous panel than on the other sides of the concrete blocks after ten years. The biomass of the benthos (shell fish, barnacles and bristle worms) on the surveyed blocks in March 2017 was 455.12 g/m² on the porous panel part and 366.25 g/m² on the smooth part of the concrete blocks. The installation of porous panel material facilitated more attachment of seaweeds than on the smoother part of the ARs making it more advantageous in creating seaweed beds.

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The kelp Saccharina japonica var. ochotensis is the most important algal resource in northern Hokkaido, Japan. The species is biennial, and fishing of the kelp is limited solely to second year sporophytes. Annual change of monthly mean surface water temperature and catch of the kelp S. japonica. var. ochotensis in northern Hokkaido, Japan, from 1980 to 2016 were compiled based on data from public organizations. Over this period, increasing water temperatures in each month contrasted with a decreasing catch of kelp. Statistical analysis using Pearson Correlation Analysis Method was conducted between mean monthly water temperature and catch of S. japonica var. ochotensis in each year. A significant correlation was found between water temperature from September to December one year prior to the fishing year and the catch of the kelp. In general, fewer individuals of the kelp transit from first year sporophyte to second year sporophyte during from October to November, and this decreased rate of transition impacts the catch. The present study suggests that lower temperatures during September to December would lead to a higher transition rate from first year sporophytes to second year sporophytes, which in turn would lead to a higher catch of kelp the following year.

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