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Kelp forests are productive coastal ecosystems that provide a range of ecosystem services. Mapping the distribution and area occupied by kelp forests is a critical step to identify their ecosystem functions and services, including their role in the carbon cycle, and to detect changes in their distribution. We compiled quantitative data of the dominant genera Laminaria and Saccharina across the Nordic region, allowing us to separate kelp forests (areas with dense or moderately dense kelp coverage) from occurrences of single or few individuals. By fitting boosted regression trees to the compiled data, we modelled and predicted the distribution of kelp forests across the Nordic region. Despite the large scale of the analyses, the models captured well the kelps’ environmental affinities and predicted the presence of kelp forests with high accuracy. Dense kelp forests are found along the rocky shores of all the Nordic countries, except in the brackish Baltic Sea, with largest areas in Norway, Greenland and Iceland. The results of this study set the scene for future studies on the importance of kelp forests in the Nordic region, including their contribution to the marine carbon budget.

Though Saccharina japonica cultivation has been established for many decades in East Asian countries, the domestication process of sugar kelp (Saccharina latissima) in the Northeast United States is still at its infancy. In this study, by using data from our breeding experience, we will demonstrate how obstacles for accelerated genetic gain can be assessed using simulation approaches that inform resource allocation decisions. Thus far, we have used 140 wild sporophytes that were sampled in 2018 from the northern Gulf of Maine to southern New England. From these sporophytes, we sampled gametophytes and made and evaluated over 600 progeny sporophytes from crosses among the gametophytes in 2019 and 2020. The biphasic life cycle of kelp gives a great advantage in selective breeding as we can potentially select both on the sporophytes and gametophytes. However, several obstacles exist, such as the amount of time it takes to complete a breeding cycle, the number of gametophytes that can be maintained in the laboratory, and whether positive selection can be conducted on farm-tested sporophytes. Using the Gulf of Maine population characteristics for heritability and effective population size, we simulated a founder population of 1,000 individuals and evaluated the impact of overcoming these obstacles on rate of genetic gain. Our results showed that key factors to improve current genetic gain rely mainly on our ability to induce reproduction of the best farm-tested sporophytes, and to accelerate the clonal vegetative growth of released gametophytes so that enough gametophyte biomass is ready for making crosses by the next growing season. Overcoming these challenges could improve rates of genetic gain more than 2-fold. Future re-search should focus on conditions favorable for inducing spring reproduction, and on increasing the amount of gametophyte tissue available in time to make fall crosses in the same year. [ABSTRACT FROM AUTHOR]

Enriching foods with long‐chain n‐3 polyunsaturated fatty acids requires a delivery emulsion system, which is both thermodynamically and oxidatively stable. The antioxidant and stabilizing properties of three types of polysaccharide extracts from brown algae Saccharina latissima with a mixed composition of polysaccharides (SA: 98% sodium alginate, SF: 90% alginate and 9% fucoidan, SL: 14.5% fucoidan, 9.5% laminarin, and co‐extracted nonpolysaccharides) were evaluated. SA, SF, SL, and REF (added commercial sodium alginate) showed in vitro ferrous ion chelating ability in the order: SA (99%) > SL (78%) > REF (31%) > SF (16%). The difference in antioxidant activity between SA, REF, and SF appeared related to structural differences of alginate (M/G ratio). A storage trial was conducted using 70% (w/w) fish oil‐in‐water delivery emulsions added sodium caseinate (NaCas) (0.23 wt%) as emulsifier in combination with SA, SF, SL, or commercial NaAlg (REF) in different concentrations (C1 = 0.1, C2 = 0.2, C3 = 0.3, and C4 = 0.4 wt%). A control with only NaCas was included (CON). The physical (e.g., creaming and droplet‐size distribution) and oxidative (peroxide value and volatiles) stability of the emulsions, were evaluated (12 days, dark at 20˚C). Acceptable physical stability (creaming index) was found for REF (all concentrations), SF = 0.2 wt% (C2), SL and SA = 0.3 wt% (C3) and 0.4 wt% (C4). In general, the oxidative stability decreased by adding REF, SA, and SF (except for REF at C1), as prooxidant activity was observed. However, SA showed antioxidant activity against the formation of 2‐ethylfuran. SL showed antioxidant activity in decreasing the formation of volatile compounds in emulsions when added in concentrations above 0.2 wt%. [ABSTRACT FROM AUTHOR]

Inconsistency in maturation of saccharinan kelp due to changes in the marine environment is a problem in terms of securing seedlings for aquaculture. In Hokkaido, the main producing area of Saccharina japonica, it has become a challenge to stably secure the parental algae of the species for aquaculture. When maturation was induced by short‐day conditions in naturally collected S. japonica sporophytes as well as in the sporophytes collected from them and cultivated, sorus formation began in approximately 3 weeks and spread to 0.4%–16.8% on the upper side area and 23.2%–41.1% on the underside area after about 5 weeks, with the highest rates, 23.2%–59.5%, observed around the base part of the underside. Sorus formation began from the base and middle parts in the top‐intact thalli and from the marginal part in the top‐cut thalli. The released zoospore germlings grew steadily as aquaculture seedlings, and the blade width and wet weight of the seedlings collected in August and subjected to mariculture in November were significantly larger after approximately five and a half months compared to those of thalli cultivated using a conventional method (i.e. thalli collected just prior to the mariculture). Seedling production through maturation induction in sporophytes would be a feasible option for seedling production facilities and would be helpful for stably producing seedlings without the effect of the natural environment. [ABSTRACT FROM AUTHOR]

The intake of Saccharina japonica (SJ), a widely consumed brown seaweed, has been reported to decrease blood pressure (BP) in hypertensive rats. It has been suggested that this effect is related to an increase in fecal sodium excretion (SE) by alginate (Alg) to the gastrointestinal tract; however, the mechanism is still unclear. This study investigated how different seaweeds with different amounts of Alg suppressed BP increase and enhanced fecal SE in 2-kidney, 1-clip renovascular hypertensive (2K1C) rats given SJ diet. Rats with 2K1C or sham operation were fed a normal-/high-salt diet with some kinds of seaweeds (5.0%, w/w) or SJ extract with different Alg contents for 6 weeks. We measured systolic BP every week and mean arterial pressure at the end, and measured the total and molecular weights of Alg in each seaweed. Then, we evaluated the relationship of the Alg amount in each seaweed with the suppression of BP increase in 2K1C rats. Finally, urinary and fecal SE for 24 h was measured. The intake of SJ, SJ extract, Saccharina ochotensis (SO) blades and SO roots suppressed BP increase in 2K1C rats, but the strength was not proportional to the amounts of Alg contained in the seaweeds. Although SJ intake increased fecal SE in 2K1C rats fed a high-salt diet, the fecal SE was much less than urinary SE. The sodium excretion in feces by Alg in SJ may not be one of the major mechanisms by which SJ intake attenuates hypertension in 2K1C rats. [ABSTRACT FROM AUTHOR]

Distribution of the kelp boring parasitic amphipod Ceinina japonica Stephensen, 1933 of the kelp Saccharina japonica var. ochotensis (Miyabe) N. Yotsukura, S. Kawashima, T. Kawai, T. Abe & L. D. Druehl in Rishiri and Rebun Islands was researched from April to July 2016. They occur widely on the coasts of both islands. An illustration of C. japonica from Rebun Island is provided. Under laboratory conditions, C. japonica have two transition ways of transitions from old host kelp to new host, one is by crawling to the new host and another is by swimming. [ABSTRACT FROM AUTHOR]

Saccharina sculpera is highly valued for human consumption and value-added products. However, natural resources of this kelp have decreased sharply and it is in danger of extinction. Resources recovery through cultivation is being trialed to enable the sustainable use of this species. In this study, the temperature range for survival and optimal growth of juvenile S. sculpera was identified and applied to field cultivation. This study investigated the survival and growth of juvenile S. sculpera under six temperatures (i.e., 5, 10, 15, 16, 18, and 20°C) and two light intensities (i.e., 20 and 40 µmol photons m-2 s-1) in an indoor culture experiment. In these experiments, the blade length decreased at 16°C under the both light intensities. The thalli died at 20°C and 20 µmol photons m-2 s-1, and at 18--20°C and 40 µmol photons m-2 s-1. During the field cultivation, early growth of S. sculpera was highest at the 5 m depth and growth decreased as the water depth increased. When the initial rearing depth was maintained without adjustment throughout the cultivation period (from December to October), all the cultivated S. sculpera plants died during August and September. However, S. sculpera plants lowered from 5 to 15 m and grew to 90.8 ± 13.1 cm in July. The seawater temperature at 15 m depth was similar to the upper level of thermal tolerance demonstrated by juvenile S. sculpera in the indoor culture experiments (16°C or lower). The plants were subsequently lowered to 25 m depth in August, which eventually led to their maturation in October. The present study confirmed that improved growth rates and a delay in biomass loss can be achieved by adjusting the depth at which the seaweeds are grown during the cultivation period. These results will contribute to the establishment of sustainable cultivation systems for S. sculpera. [ABSTRACT FROM AUTHOR]

Brown algae represent a valuable source of various biologically active compounds. Their accumulation is influenced by many environmental factors. The purpose of this study was a comparison of the total chemical composition of brown algae from the White and Yellow Seas to substantiate the possibility of their use for production of new pharmaceutical substances. Using a scheme, which involves consecutive supercritical fluid, acid, alkaline and water extractions, various components of brown algae have been isolated including a protein-polysaccharide complex, which, in the case of Laminaria digitata and L. saccharina, consisted of cellulose and proteins for more than 80%. FTIR spectroscopy has confirmed the qualitative composition of the complex and indicated its purity. Significant differences in the elemental and component composition affected by growing conditions of macrophytes have been revealed. Chemical compounds obtained from brown algae biomass, especially the protein–polysaccharide complex, have a high potential as a basis for new pharmacological preparations for health protection purposes. Based on the earlier obtained data, one can suppose this complex has both enterosorption and immunomodulatory activity. [ABSTRACT FROM AUTHOR]

Emerging knowledge shows the importance of preweaning nutrition on programming the gastrointestinal microbiome and development of the gut barrier function. The aim of this study was to assess the effects of supplementing cow milk with either intact dried Ulva sp., Ascophyllum nodosum , or Saccharina latissima on growth performance and several gut health parameters of preweaning dairy calves. Forty male Holstein calves were selected based on birth weight (41 ± 4 kg) and plasma Brix percentage (≥8.7%) at d 2 of life. From d 2 to d 42 of life, the control calves (n = 10) were fed with cow milk (8 L/d) without seaweed supplementation, and the experimental calves were fed with cow milk (8 L/d) supplemented with either Ulva sp. (n = 10), A. nodosum (n = 10), or S. latissima (n = 10) at a concentration of 50 g/8 L of cow milk per day (i.e., 5% on a dry matter basis). Calves were weighed every week, and body weight gain and calf starter intake were monitored weekly. At d 42 ± 3 of life, calves were slaughtered. The organ weights and digesta pH from the reticulorumen, mid- and end small intestine, and mid-colon were recorded. A tissue sample (5 cm) collected from the mid-small intestine was analyzed for histomorphology. Digesta from the mid-small intestine and mid-colon were analyzed for lactobacilli, Escherichia coli , and Enterobacteriaceae , and short-chain fatty acid profile. Weight gain of the calves was not affected by seaweed supplementation. Proportional organ weights were not affected by seaweed supplementation except for reticulorumen weight, which was higher in calves fed Ulva sp. Both the mid-small intestinal and mid-colonic digesta populations of lactobacilli, Enterobacteriaceae , and E. coli , as well as the mid-small intestinal histomorphology in seaweed-supplemented calves were not different from control calves. However, acetic acid proportion in mid-colonic digesta was increased in calves fed Ulva sp. and A. nodosum , whereas butyric acid proportion was decreased compared with the control calves. Digesta pH in mid- and end small intestine and mid-colon were not affected, whereas ruminal pH was increased in calves fed Ulva sp. compared with the control calves. In conclusion, intact dried seaweed supplementation did not improve the growth or selected gut health parameters (i.e., histomorphology, digesta pH, bacteria, and short-chain fatty acids) in preweaning Holstein calves. [ABSTRACT FROM AUTHOR]

Delayed gametophytes are able to grow vegetatively for prolonged periods of time. As such, they are potentially very valuable for kelp aquaculture given their great promise in opening up novel opportunities for kelp breeding and farming. However, large‐scale application would require more in‐depth understanding of how to control reproduction in delayed gametophytes. For newly formed gametophytes, many environmental factors for reproduction have been identified, with key drivers being light intensity, temperature, and the initial gametophyte density. However, the question of whether delayed gametophytes react similarly to these life cycle controls remains open for exploration. In this study, we performed a full factorial experiment on the influences of light intensity, temperature, and density on the reproduction of multiannual delayed gametophytes of Saccharina latissima, during which the number of sporophytes formed was counted. We demonstrate that delayed gametophytes of S. latissima can reliably reproduce sexually after more than a year of vegetative growth, depending on the effects between light intensity and temperature. Under higher light intensities (≥29 µmol photons · m−2 · s−1), optimal reproduction was observed at lower temperatures (10.2°C), while at lower light intensities (≤15 µmol photons · m−2 · s−1), optimal reproduction was observed at higher temperatures (≥12.6°C). Given the seasonal lag between solar radiation and sea surface temperature in natural systems, these conditions resemble those found during spring (i.e., increasing light intensity with low temperatures) and autumn (i.e., decreasing light intensity with higher temperatures). Seasonality can be used as an aquaculture tool to better control the reproduction of delayed gametophytes. [ABSTRACT FROM AUTHOR]

As kelp cultivation increases around the world, so does the need for farm management strategies that produce specific crop characteristics, optimize yield, widen harvesting windows, and prevent biomass loss. Distal‐end trimming of macroalgae has been recommended as a farm management method addressing these needs. In this study, we trimmed cultivated Saccharina latissima sporophytes grown in the Western Gulf of Maine (WGoM) to 60 cm above the stipe–blade interface. We characterized the effect of trimming on the morphology, tissue nutrient content, stable isotope ratio, and nitrate reductase activity of the kelp. We also evaluated the economic trade‐offs of trimming using a simple production model. The results suggest that trimming the blade to 60 cm may have minimal biological consequences. Additionally, the trimming appears to benefit "short" kelp blades in proximity to the trimmed blades. Daily yield (% increase in weight day−1) after trimming was initially lower than the control, but late‐season daily yields and crop‐retention following storms were markedly improved. Ultimately, we conclude that growers could use trimming to acquire kelp biomass earlier in the season, retain late‐season biomass, and potentially increase the total revenue gained from kelp farming if price premiums can be exacted for this biomass. [ABSTRACT FROM AUTHOR]

We describe a method for production of kelp using meiospore seeding creating flexibility for extended storage time prior to outplanting. One bottleneck to expansion of the kelp farming industry is the lack of flexibility in timing of seeded twine production, which is dependent on the fertility of wild sporophytes. We tested methods to slow gametophyte growth and reproduction of early life stages by manipulating temperature of the kelp Saccharina latissima. Reducing temperature from 12°C to 4°C reduced gametophyte size, sporophyte size, egg production, and sporophyte production and subsequently was the best candidate condition for storage experiments of seeded twine. Next, we examined how storage of Alaria marginata and S. latissima seeded twine at 4°C under differing nutrient concentrations affected the viability of sporelings after being moved into optimal growth conditions. Seeded twine storage at 4°C with no alteration to culturing media showed no negative effects in sporophyte density and sporophyte length for both species. This method for seeded twine storage, "cold banking," allowed seeded twine storage for at least an additional 36 days compared to standard methods, with a total of 56 days spent in the hatchery providing opportunity for outplanting timing and staggering to enhance aquaculture efficiency. [ABSTRACT FROM AUTHOR]

Our team has initiated a selective breeding program for regional strains of sugar kelp, Saccharina latissima, to improve the competitiveness of kelp farming in the United States. Within our breeding program, we also include an endemic putative species, Saccharina angustissima, locally referred to as skinny kelp. We crossed uniclonal gametophyte cultures derived from 37 wild‐collected blades representing five sugar kelp strains and one skinny kelp strain to produce 104 unique crosses. Each cross was outplanted on a near‐shore research farm located in the Gulf of Maine (GOM). After the first farming season, our results indicated that sugar kelp and skinny kelp were interfertile, and produced mature and reproductively viable sporophytes. Morphological traits of individual blades varied depending on the parental contribution (sugar vs. skinny), with significant differences found in progeny blade length, width, thickness, and in stipe length and diameter. Despite these differences, wet weight and blade density per plot showed no statistical differences regardless of the cross. Given their published genetic similarity and their interfertility shown here, S. angustissima and S. latissima may not be different species, and may each contribute genetic diversity to breeding programs aimed at meeting ocean farming and market needs. [ABSTRACT FROM AUTHOR]

There has been increasing interest in Alaska regarding the commercial mariculture of kelp. Kelp farming can be an economic engine for coastal communities of Alaska. Other benefits include ecosystem services, including carbon sequestration and mitigation of eutrophication. In support of this interest, several kelp species have been examined for commercial potential. In the 1980s–1990s, experiments were performed on the giant kelp Macrocystis pyrifera. Female gametophytes were exposed to varying levels of chelated iron. Relatively low levels of chelated iron (1–5 μM) stimulated the onset of oogenesis. In contrast, higher iron concentrations inhibited egg production. Outplant experiments with Macrocystis in Sitka, AK showed growth in the winter and spring, slowing down to zero growth by the end of summer. Fertilizing outplants in August allowed plants to survive and grow during the ensuing winter. Mariculture experiments with Saccharina latissima carried out near Juneau, Alaska showed exponential growth for seeded lines set out from September to March. Optimal growth occurred for outplants in October–November, with growth rates of up to 5% per day. The best growth occurred when lines were 2–3 m below the surface. Growth rates declined in May–June corresponding to a decrease in inorganic nitrogen in the water. Slower growth also resulted in severe fouling. [ABSTRACT FROM AUTHOR]

In this work, the complete mitogenome of Saccharina cultivar ‘Dongfang No.3’ is reported. This mitogenome has a circular mapping organization with the length of 37,657 bp and contains 66 genes, including 35 protein-coding genes, three rRNAs, 25 tRNAs, and three open reading frames (orfs). The overall AT content is 64.73%, showing a higher AT content. The gene content and gene sequence are consistent with those reported varieties and cultivars of Saccharina. Chinese main Saccharina cultivars are analyzed by phylogenetic analysis. It indicates that ‘Dongfang No.3’ has a close relationship with Saccharina japonica, which strongly supports its genetic origin. The complete mitogenome analysis in this work would help in understanding the genetic background of Chinese Saccharina cultivars.

The culturing and investigation of individual marine specimens in lab environments is crucial to further our understanding of this highly complex ecosystem. However, the obtained results and their relevance are often limited by a lack of suitable experimental setups enabling controlled specimen growth in a natural environment while allowing for precise monitoring and in-depth observations. In this work, we explore the viability of a microfluidic device for the investigation of the growth of the alga Saccharina latissima to enable high-resolution imaging by confining the samples, which usually grow in 3D, to a single 2D plane. We evaluate the specimen’s health based on various factors such as its growth rate, cell shape, and major developmental steps with regard to the device’s operating parameters and flow conditions before demonstrating its compatibility with state-of-the-art microscopy imaging technologies such as the skeletonisation of the specimen through calcofluor white-based vital staining of its cell contours as well as the immunolocalisation of the specimen’s cell wall. Furthermore, by making use of the on-chip characterisation capabilities, we investigate the influence of altered environmental illuminations on the embryonic development using blue and red light. Finally, live tracking of fluorescent microspheres deposited on the surface of the embryo permits the quantitative characterisation of growth at various locations of the organism.

The brown alga Saccharina japonica is widely consumed in Asian countries, and post-harvest drying methods such as sun drying and oven drying are commonly used to extend the shelf life of S. japonica. Thus, the present study analyzed the ethanol extract and organic solvent fractions of S. japonica to examine the effects of UVA and heating on certain bioactive compounds (fucoxanthin, phlorotannin compounds, and total antioxidants) during the drying process. The fucoxanthin contents in the ethanol extract and different solvent fractions significantly decreased in response to UVA. However, fucoxanthin in the ethanol extract and other fractions showed resistance to thermal treatment. It is noteworthy that the total phlorotannin content (TPC) in the ethanol extract and all fractions showed an approximately 2.5-fold increase upon UVA radiation. The TPC also increased in all samples exposed to high temperatures, except for those in the chloroform fraction. The total antioxidant capacity (TAC) also exhibited significant increases in a pattern similar to the TPC. The findings demonstrate that UVA exposure and heating stimulated the degradation of fucoxanthin while it increased the TPC and TAC in the extract and fractions of S. japonica. [ABSTRACT FROM AUTHOR]

Background: In brown algae, dioicy is the prevalent sexual system, and phenotypic differences between male and female gametophytes have been found in many dioicous species. Saccharina japonica show remarkable sexual dimorphism in gametophytes before gametogenesis. A higher level of phenotypic differentiation was also found in female and male gametes after gametogenesis. However, the patterns of differential gene expression throughout gametophyte development and how these changes might relate to sex-specific fitness at the gamete stage in S. japonica are not well known. Results: In this study, differences in gene expression between male and female gametophytes in different developmental stages were investigated using comparative transcriptome analysis. Among the 20,151 genes expressed in the haploid gametophyte generation, 37.53% were sex-biased. The abundance of sex-biased genes in mature gametophytes was much higher than that in immature gametophytes, and more male-biased than female-biased genes were observed in the mature stage. The predicted functions of most sex-biased genes were closely related to the sex-specific characteristics of gametes, including cell wall biosynthesis, sperm motility, and sperm and egg recognition. In addition, 51 genes were specifically expressed in males in both stages, showing great potential as candidate male sex-determining region (SDR) genes. Conclusions: This study describes a thorough investigation into differential gene expression between male and female gametophytes in the dioicous kelp S. japonica. A large number of sex-biased genes in mature gametophytes may be associated with the divergence of phenotypic traits and physiological functions between female gametes (eggs) and male gametes (sperm) during sexual differentiation. These genes may mainly come from new sex-biased genes that have recently evolved in the S. japonica lineage. The duplication of sex-biased genes was detected, which may increase the number of sex-biased genes after gametogenesis in S. japonica to some extent. The excess of male-biased genes over female-biased genes in the mature stage may reflect the different levels of sexual selection across sexes. This study deepens our understanding of the regulation of sex development and differentiation in the dioicous kelp S. japonica. [ABSTRACT FROM AUTHOR]

This study aimed to investigate the physicochemical properties of soluble dietary fiber (SDF) and cellulose enriched in Saccharina japonica by-products and to evaluate their anti-colitis effects. The water-holding capacity (WHC), swelling capacity (SC), cation exchange capacity (CEC), and antioxidant properties of SDF were superior to cellulose. The ΔH of SDF and cellulose was 340.73 J/g and 134.56 J/g, and the average particle size of them was 43.858 μm and 97.350 μm. The viscosity of SDF was positively correlated with the content. SEM revealed that the microstructure of SDF was porous, whereas cellulose was folded. SDF contained seven monosaccharides such as mannuronic acid and mannose, while cellulose had a single glucose composition. It was also shown that both SDF and cellulose reversed the pathological process of colitis by inhibiting weight loss, preventing colon injury, balancing oxidative stress, and regulating the level of inflammation, with the optimal dose being 1.5 g/kg. The difference was that SDF inhibited the expression of NF-кB and TNF-α, while cellulose up-regulated the expression of PPAR-γ and IL-10. Additionally, SDF could more positively control the expression of ZO-1, whereas cellulose was superior in improving the expression of Occludin. Interestingly, SDF could restore the structure of norank_f_Muribaculaceae and Lachnospiraceae_NK4A136_group to ameliorate ulcerative colitis (UC), whereas cellulose mainly regulated the abundance of norank_f_Muribaculaceae , Faecalibaculum , Bacteroides and unclassified_f__Lachnospiraceae. The production of short-chain fatty acids (SCFAs) was also found to be restored by SDF and cellulose. Overall, SDF and cellulose can be considered important dietary components for treating and preventing UC. [Display omitted] [ABSTRACT FROM AUTHOR]

The short harvesting period of cultivated brown seaweed in Europe can make it difficult for cultivators to produce high quality seaweed biomass all year around. Hence there is a need for novel processing and preservation methods. Acid preservation is a well-known method to preserve food, where the aim is to reduce the pH below 4.5 to inhibit microbial growth. To evaluate the effectiveness of acid preservation, a shelf-life experiment was conducted with Saccharina latissima and Alaria esculenta. The biomass was either treated with lactic- or citric acid and stored for approximately seven months. Physicochemical (including proximate composition, trace minerals, total phenolic content (TPC), texture and pH), microbial-, sensory attributes, and antioxidant (ORAC, DPPH) analyses were performed on the preserved biomass during storage. The proximate composition, color, pH, and texture of the acid-preserved seaweed were relatively stable throughout the storage. However, a decrease was observed in TPC and antioxidant properties (assessed by DPPH) with the acid treatments. Acid preservation is, thus, a good method to stabilize the studied biomass for food and feed applications but less applicable if intended for antioxidant purposes. However, the acid treated biomass might be suitable as an ingredient for a wide range of value-added products. • Acid preservation is a suitable method to stabilize brown seaweed biomass. • Proximate composition of seaweed biomass was stable throughout the storage duration. • Total viable count (TVC) was relatively stable during storage. • The total phenolic content (TPC) of A. esculenta decreased with acid treatment. • A strong salt, seaweed, and sour flavor was detected in the acid preserved samples. [ABSTRACT FROM AUTHOR]

Carbonic anhydrase (CA) is a crucial component of CO 2 -concentrating mechanism (CCM) in macroalgae. In Saccharina japonica , an important brown seaweed, 11 CAs, including 5 α-, 3 β-, and 3 γ-CAs, have been documented. Among them, one α-CA and one β-CA were localized in the periplasmic space, one α-CA was found in the chloroplast, and one γ-CA was situated in mitochondria. Notably, the known γ-CAs have predominantly been identified in mitochondria. In this study, we identified a chloroplastic γ-type CA, Sjγ-CA2, in S. japonica. Based on the reported amino acid sequence of Sjγ-CA2, the epitope peptide for monoclonal antibody production was selected as 165 Pro-305. After purification and specificity identification, anti-SjγCA2 monoclonal antibody was employed in immunogold electron microscopy. The results illustrated that Sjγ-CA2 was localized in the chloroplasts of both gametophytes and sporophytes of S. japonica. Subsequently, immunoprecipitation coupled with LC-MS/MS analysis revealed that Sjγ-CA2 mainly interacted with photosynthesis-related proteins. Moreover, the first 65 amino acids at N-terminal of Sjγ-CA2 was identified as the chloroplast transit peptide by the transient expression of GFP-SjγCA2 fused protein in tabacco. Real-time PCR results demonstrated an up-regulation of the transcription of Sjγ-CA 2 gene in response to high CO 2 concentration. These findings implied that Sjγ-CA2 might contribute to minimizing the leakage of CO 2 from chloroplasts and help maintaining a high concentration of CO 2 around Rubisco. • A novel γ-type carbonic anhydrase (Sjγ-CA2) was localized in the chloroplast of Saccharina japonica. • Sjγ-CA2 mainly interacted with photosynthesis-related proteins in chloroplasts of S. japonica. • Sjγ-CA2 was imported into chloroplast via the Hsp70/DnaK chloroplast import system. • The transcription level of Sjγ-CA2 gene was up-regulated by high CO 2 conditions. • Sjγ-CA2 is speculated to play a role in minimizing the leakage of CO 2 from chloroplasts. [ABSTRACT FROM AUTHOR]

Chitosan films enriched with aqueous extract of Sugar kelp Saccharina latissima (SLE) were developed and characterized by measuring the equilibrium moisture, moisture content, water vapor permeability, mechanical properties, antioxidant properties, optical properties, surface morphology and thermostability. The developed films were tested as separators with antioxidant properties for sliced Havarti cheese. The addition of SLE showed a decrease in mechanical properties such as tensile strength from 48.99 to 36.16 MPa and Young's Modulus from 929.49 to 743.71 MPa compared with pure chitosan films. The resulting chitosan-SLE films showed a high free-radical scavenging activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) (ABTS+). Moreover, the presence of SLE in the chitosan matrix significantly improved the UV-barrier of the samples. When the chitosan-SLE films were employed as separators for cheese, a significant reduction of 52.8% in cheese lipid oxidation was observed after 45 days of refrigerated storage compared to the control group using chitosan films. Hence, an environmentally sustainable alternative to synthetic and non-biodegradable slice separators has been successfully developed using chitosan, a by-product of the fishing industry, fortified with an extract from sugar kelp, a commonly found brown algae. [Display omitted] • Chitosan- Sugar kelp Saccharina latissima (SLE) films were developed. • Chitosan-SLE films were applied as sustainable sliced-cheese separators. • Chitosan-SLE films boost UV-barrier, protecting cheese quality. • Antioxidant chitosan-SLE films: High DPPH and ABTS + activity. • Chitosan-SLE films reduced cheese lipid oxidation by 52.8%. [ABSTRACT FROM AUTHOR]

We previously reported the alginate lyase, SjAly, from a brown alga, Saccharina japonica , providing the first experimental evidence for a functional alginate-degradation enzyme in brown algae. 4-deoxy-L- erythro -5-hexoseulose uronate (DEHU), derived from an unsaturated monosaccharide, was identified as the minimum degradation product produced by SjAly-mediated lysis of alginate. DEHU was hitherto reported to be reduced to 2-keto-3-deoxy-gluconate (KDG) by a DEHU-specific reductase with NAD(P)H in alginate-assimilating organisms and its metabolism in alginate-producing organisms is unknown. Here, we report the functional identification of a DEHU reductase, SjRed, in S. japonica. Among the 14 tested compounds, only DEHU was used as a substrate and was converted to KDG in the presence of NADPH. Optimum temperature, pH, and KCl concentration required for SjRed activity were determined to be 25 °C, 7.2, and 100 mM, respectively. SjRed consists of 341 amino acid residues and is proposed to be a member of the aldo-keto reductase superfamily. Sequencing of SjRed revealed that it is composed of at least three exons. These results indicate the existence of an enzyme that reduces DEHU to KDG in S. japonica. This is the first report on the functional identification of a DEHU-reductase in alginate-producing organisms. • Novel DEHU reductase, SjRed, was functionally identified from a brown alga. • SjRed belongs to the aldo-keto reductase superfamily. • SjRed is the first DEHU reductase discovered in any alginate-producing organisms. [ABSTRACT FROM AUTHOR]

It has been reported that there was a linkage of 5S rRNA gene to 18S-5.8S-25S rRNA gene in a few of species in Ochrophyta. In regard to the usual two positions of linked 5S rDNA to the 3′ end of 25S rDNA, two pairs of primers were designed for amplification to verify this linkage of two genes in a kelp cultivar of Saccharina japonica, one of species in Ochrophyta. This result supplemented the previous report that 5S rDNA was unlinked to 25S rDNA in this kelp. In order to simultaneously visualize this unlinkage of two genes, dual-color fluorescence in situ hybridization (FISH) technique was applied to the cytogenetics of S. japonica. Dual-color FISH images showed that two and four hybridization signals were present in the kelp gametophyte and sporophyte, respectively, metaphase nuclei hybridized simultaneously with the labeled probes of 18S rDNA and 5S rDNA. Both haploid and diploid karyotypes in decreasing length of chromosomes showed that 18S-5.8S-25S rDNA was localized at the interstitial region of Chromosome 23, whereas 5S rDNA resided at the sub-telomeric region of Chromosome 27. These karyotypes suggested that the kelp nuclear genome had only one locus of each rRNA gene, and their loci on different chromosomes indicated the physical unlinkage of 5S rDNA to 18S-5.8S-25S rDNA in this kelp. Therefore, dual-color FISH seems to be a powerful technique for the discrimination and pairing of chromosomes featured in both small size and nearly identical shape in S. japonica. [ABSTRACT FROM AUTHOR]

Saccharina japonica is an important large brown alga and a major component of productive beds on the northwest coast of the Pacific Ocean. Abiotic stress response mechanisms are receiving considerable attention because global climate change is increasing their abiotic stress levels. However, our knowledge of how S. japonica broadly responds to stress is limited. In this study, we investigated the S. japonica responsive genes underlying acclimation to diverse stressors of acidification, high light, high temperature, hypersalinity, and hyposalinity and identified 408 core genes constantly and differentially expressed in response to all stressors. Our results confirm that stressors had strong effects on genes participating in photosynthesis, amino acid metabolism, carbohydrate metabolism, halogen metabolism, and reactive oxygen species defense. These findings will improve our understanding of brown algal response mechanisms linked to environmental stress and provide a list of candidate genes for improving algal stress tolerance in light of environmental stress in future studies. [ABSTRACT FROM AUTHOR]

Kelps provide critical services for coastal food chains and ecosystem, and they are important food source for some segments of human population. Despite their ecological importance, little is known about long‐term impacts of elevated CO2 (eCO2) on nutrient metabolites in kelps and the underlying regulation mechanisms. In this study, the kelp Saccharina japonica was cultured in CO2‐enriched coastal mesocosm systems for up to 3 months. We found that, although eCO2 significantly increased the growth rate, carbon concentrations, and C/N ratio of S. japonica, and it had no effect on total nitrogen and protein contents at the end of cultivation period. Meanwhile, it decreased the lipid, magnesium, sodium, and calcium content and changed the amino acid and fatty acid composition. Combining the genome‐wide transcriptomic and metabolic evidence, we obtained a system‐level understanding of metabolic response of S. japonica to eCO2. The unique ornithine–urea cycle (OUC) and aspartate‐argininosuccinate shunt (AAS), coupled with TCA cycle, balanced the carbon and nitrogen metabolism under eCO2 by providing carbon skeleton for amino acid synthesis and reduced power for nitrogen assimilation. This research provides a major advance in the understanding of kelp nutrient metabolic mechanism in the context of global climate change, and such CO2‐induced shifts in nutritional value may induce changes in the structure and stability of marine trophic webs and affect the quality of human nutrition resources. [ABSTRACT FROM AUTHOR]

Periplasmic or external carbonic anhydrases (CAs) have been well accepted as playing a crucial role in the acquisition of dissolved inorganic carbon; however, no cytological evidence or molecular information on these enzymes has been reported in seaweeds to date. In this study, the full‐length cDNA sequence coding for a putative periplasmic Sjα‐CA2 was cloned from the gametophytes of Saccharina japonica, an industrial brown seaweed. It was 1,728 bp in length and included a 263‐bp 5′‐untranslated region (UTR), a 577‐bp 3′‐UTR, and an 888‐bp open reading frame encoding a protein precursor consisting of 295 amino acids. The mature protein, after removal of a predicted 28‐residue signal peptide, was composed of 267 amino acids with a relative molecular weight of 29.27 kDa. Multisequence alignment and phylogenetic analysis indicated that it was a member of the α‐CA family. Enzyme activity assays showed that the recombinant Sjα‐CA2 in Escherichia coli possessed CO2 hydration and esterase activities, thus identifying this gene Sjα‐CA2 in function. Immunogold electron microscopic observations with the prepared anti‐Sjα‐CA2 polyclonal antibody illustrated that Sjα‐CA2 was located in periplasmic space of the kelp gametophyte cells. Quantitative real‐time PCR results revealed that the transcription of Sjα‐CA2 was induced by elevated HCO3‐ levels, but it was little changed while the kelp gametophytes were subjected to elevated CO2 concentrations. This study suggests that the periplasmic Sjα‐CA2 might play a role in adapting to elevated environmental levels of HCO3‐ by dehydration of HCO3‐ to generate CO2, which could be readily taken up by S. japonica gametophytes. [ABSTRACT FROM AUTHOR]

The interest in cultivating seaweed in European seas as source of food, feed and feedstock for the biobased economy is growing. Amongst the species investigated is kelp, also known as sugar kelp, Saccharina latissima or Laminaria saccharina. The European kelp sector is relatively small, compared to the global production and use, yet growth of the sector is aimed for. An inevitable question for European seaweed producers is how they can compete in the global seaweed value chain. This paper assesses to what extent the European strategy for growing the kelp sector matches with the dynamics of current kelp value chain. The global value chains (GVC) framework is applied to study how the global kelp sector is organized, including analysis of trends in science and patents. The upgrading strategy deployed by the European sector is critically evaluated against this framework. The analysis points towards various dividing lines between the established kelp cultivation and processing industry in Asia and the (far smaller) nascent cultivation and processing industry for high-value applications. These represent two unconnected worlds. Chain or intra-sectoral upgrading to spur the European kelp sector could occur if European food sector engage more closely with the European producers. Those bring financial power and a broader client base to the table and are instrumental in linking production to the demands of end-users. [ABSTRACT FROM AUTHOR]

Natural hybridization can play a significant role in evolutionary processes and influence the adaptive diversification and speciation of brown seaweeds. However, this phenomenon is as yet unknown in Saccharina kelps. Saccharina angustata and two varieties of Saccharina japonica (S. japonica var. japonica and S. japonica var. diabolica) partly overlap in distribution along the Pacific coast of Hokkaido, which makes them a good model system to study hybridization and introgression among species of the genus Saccharina. Based on 13 highly variable nuclear microsatellites and a mitochondrial marker, we assessed the genetic diversity levels of S. angustata for the first time and populations from Muroran to Shiranuka (western part of the Pacific coast in Hokkaido) exhibited highest genetic diversity. Genetic diversity of S. japonica was higher in S. japonica var. japonica as compared with S. japonica var. diabolica. There was significant genetic differentiation (FST > 0.25, p < 0.05) between S. japonica and S. angustata based on both markers. Moreover, there was poor genetic connectivity and limited interspecific hybridization among these closely related Saccharina species. Ecological niche models projected a northward expansion of both S. japonica and S. angustata under future climate scenarios and a range overlap between two species along the coast of Okhotsk Sea in Kamchatka Peninsula. The interspecific hybridization and genetic diversity among these kelps provide insights for kelp selection and cultivation as well as future conservation strategies of wild stocks. [ABSTRACT FROM AUTHOR]

Seaweed cultivation and processing industries could contribute to sustainable blue growth and the European bioeconomy. This article contributes a case study evaluation of environmental sustainability of preserved brown seaweed Saccharina latissima by means of environmental life cycle assessment of a pilot facility in Sweden. The study accounts for nutrient bioremediation and carbon capture and includes two alternative hatchery processes, a 2-ha longline cultivation, and four alternative preservation methods (hang-drying outdoors, heated air-cabinet drying, ensiling, and freezing). The study found that as a result of carbon capture and nitrogen and phosphorus uptake (bioremediation) by seaweed, more CO2 and PO4 equivalents are (temporarily) absorbed than emitted by the supply chain. The extent of emissions is most affected by preservation methods undertaken. Impact profiles of the supply chain show that the greatest impact shares result from freezing and air-cabinet drying, both the two most energy-intensive processes, followed by the cultivation infrastructure, highlighting strategic optimization opportunities. Hatchery processes, harvesting, and the low-energy ensilage and hang-drying outdoors were found to have relatively small impact shares. These findings presage the environmentally friendliness of seaweed-based products by documenting their potential to mitigate eutrophication and climate change, even when taking a life cycle perspective. [ABSTRACT FROM AUTHOR]

SUMMARY: "Monitoring Sites 1000" – Japan's long‐term monitoring survey was established in 2003, based on the Japanese Government policy for the conservation of biodiversity. Ecological surveys have been conducted on various types of ecosystems at approximately 1000 sites in Japan for 15 years now and are planned to be carried out for 100 years. Since 2008, seaweed communities had been monitored at six sites, featuring the kelp (e.g. Saccharina and Ecklonia; Laminariales) and Sargassum (Fucales) communities in the subarctic and temperate regions of Japan. Annual surveys were carried out during the season when these canopy‐forming seaweeds are most abundant. A non‐destructive quadrat sampling method, with permanent quadrats placed along transects perpendicular to the shoreline, was used to determine species composition, coverage, and vertical distribution of seaweeds at these sites; while destructive sampling was done every 5 years to determine biomass. The occurrence of canopy‐forming species Saccharina japonica (var. japonica) and Ecklonia cava have appeared to be stable at the Muroran (southwestern part of Hokkaido Island) and Shimoda (Pacific coast of middle Honshu Island) sites, respectively; whereas the coverage of Ecklonia radicosa (= Eckloniopsis radicosa) at the Satsuma‐Nagashima site in southern part of Kyushu Island was highly variable until its sudden disappearance from the habitat in 2016. Thalli of E. radicosa lost most of their blades through browsing by herbivorous fish, and thus, this may be one of the causes of the decline. A shift in the community structure related to environmental changes had also been observed at some other sites. Pre‐ and post‐disaster data revealed the impact of the 2011 earthquake and tsunami disasters, including a shift in the vertical distribution of Ecklonia bicyclis (= Eisenia bicyclis) to shallower depths at the Shizugawa site in the Pacific coast of northern Honshu Island, due to seafloor subsidence. [ABSTRACT FROM AUTHOR]

SUMMARY The sugar kelp Saccharina latissima experiences a wide range of environmental conditions along its geographical and vertical distribution range. Temperature and salinity are two critical drivers influencing growth, photosynthesis and biochemical composition. Moreover, interactive effects might modify the results described for single effects. In shallow water coastal systems, exposure to rising temperatures and low salinity are expected as consequence of global warming, increased precipitation and coastal run‐off. To understand the acclimation mechanisms of S. latissima to changes in temperature and salinity and their interactions, we performed a mechanistic laboratory experiment in which juvenile sporophytes from Brittany, France were exposed to a combination of three temperatures (0, 8 and 15°C) and two salinity levels (20 and 30 psu (practical salinity units)). After a temperature acclimation of 7 days, sporophytes were exposed to low salinity (20 psu) for a period of 11 days. Growth, and maximal quantum yield of photosystem II (Fv/Fm), pigments, mannitol content and C:N ratio were measured over time. We report for the first time in S. latissima a fivefold increase in the osmolyte mannitol in response to low temperature (0°C) compared to 8 and 15°C that may have ecological and economic implications. Low temperatures significantly affected all parameters, mostly in a negative way. Chlorophyll a, the accessory pigment pool, growth and Fv/Fm were significantly lower at 0°C, while the de‐epoxidation state of the xanthophyll cycle was increased at both 0 and 8°C compared to 15°C. Mannitol content and growth decreased with decreased salinity; in contrast, pigment content and Fv/Fm were to a large extent irresponsive to salinity. In comparison to S. latissima originating from an Arctic population, despite some reported differences, this study reveals a remarkably similar impact of temperature and salinity variation, reflecting the large degree of adaptability in this species. [ABSTRACT FROM AUTHOR]

Low-molecular-weight metabolites known as mycotoxins of micromycetes from the genera Fusarium, Alternaria, Penicillium, Aspergillus, etc. were studied using the enzyme immunoassay in the brown algae Ascophyllum nodosum, Pelvetia canaliculata, Fucus vesiculosus, Laminaria digitata, and Saccharina latissima collected from the Kandalaksha Gulf, White Sea. The T-2 toxin, diacetoxyscirpenol, deoxynivalenol, zearalenone, fumonisins of group B, alternariol, ochratoxin A, citrinin, PR-toxin, mycophenolic acid, aflatoxin B1, sterigmatocystin, cyclopiazonic acid, emodin, roridin A, and ergot alkaloids were detected in thalli of A. nodosum, P. canaliculata, and F. vesiculosus. The latter species was found to contain almost all of the above-listed mycotoxins in significant amounts. P.canaliculata had lower levels of PR-toxin, mycophenolic acid, emodin, and roridin A than those recorded from A. nodosum, whereas the levels of the other substances did not differ significantly between these species. L. digitata and S. latissima contained only ergot alkaloids in trace amounts, and no other mycotoxins were detected. [ABSTRACT FROM AUTHOR]

In Alaska, interest in harvesting seaweeds for personal use is growing and information on potential impacts of this activity on sustainability of wild populations is lacking. This study provides information on reproductive timing and size, standing crop, and harvest rebound of three commonly harvested seaweeds in Southcentral Alaska: the rockweed, Fucus distichus; the sugar kelp, Saccharina latissima; and the bull kelp, Nereocystis luetkeana. From March through October 2018, seaweeds were surveyed for reproductive status and harvested to determine how much biomass was available. From the harvests, individuals were measured to determine the size when they first become reproductive. Harvested plots were re-harvested to determine biomass regrowth after 2, 4, and 6 months. Fucus and Nereocystis were broadly reproductive over the summer, while Saccharina was not. The presence of reproductive Fucus and Nereocystis throughout the summer could buffer the impacts of late season harvesting. Depending on the species (e.g., Fucus), individuals that became reproductive at a larger size were associated with lower density and lower biomass areas with slower recovery. The amount of biomass available for harvest and the amount that regrew following a harvest were temporally variable but had spatial differences that were consistent throughout the summer. Regrowth following harvesting for all three species was generally low after only 2 months, but the amount of biomass after 6 months post-harvesting was sometimes comparable to non-harvested areas. This study demonstrated that to varying extents, seaweed harvesting may be sustainable if timing of reproduction, available biomass, and regrowth are all considered. [ABSTRACT FROM AUTHOR]

The SARS-CoV-2 spike glycoproteins (SGPs) and human angiotensin converting enzyme 2 (ACE2) are the two key targets for the prevention and treatment of COVID-19. Host cell surface heparan sulfate (HS) is believed to interact with SARS-CoV-2 SGPs to facilitate host cell entry. In the current study, a series of polysaccharides from Saccharina japonica were prepared to investigate the structure-activity relationship on the binding abilities of polysaccharides (oligosaccharides) to pseudotype particles, including SARS-CoV-2 SGPs, and ACE2 using surface plasmon resonance. Sulfated galactofucan (SJ-D-S-H) and glucuronomannan (Gn) displayed strongly inhibited interaction between SARS-CoV-2 SGPs and heparin while showing negligible inhibition of the interaction between SARS-CoV-2 SGPs and ACE2. The IC 50 values of SJ-D-S-H and Gn in blocking heparin SGP binding were 27 and 231 nM, respectively. NMR analysis showed that the structure of SJ-D-S-H featured with a backbone of 1, 3-linked α-L-Fuc p residues sulfated at C4 and C2/C4 and 1, 3-linked α-L-Fuc p residues sulfated at C4 and branched with 1, 6-linked β-D-galacto-biose; Gn had a backbone of alternating 1, 4-linked β-D-GlcA p residues and 1, 2-linked α-D-Man p residues. The sulfated galactofucan and glucuronomannan showed strong binding ability to SARS-CoV-2 SGPs, suggesting that these polysaccharides might be good candidates for preventing and/or treating SARS-CoV-2. [ABSTRACT FROM AUTHOR]

Low molecular weight fucoidan (LMWF) extracted from Saccharina japonica exhibits many biological activities including immune regulation and inhibition of tumor angiogenesis, but little research has been done for its antioxidant effect in atherosclerosis (AS). In this study, AS modeling was successfully conducted in ApoE-/- mice by feeding atherogenic diet to animals. The antioxidant activity of LMWF was verified by determining its superoxide anion radical scavenging ability and hydroxyl radical scavenging ability. LMWF significantly increased the antioxidant capacity of AS mice, this conclusion being confirmed by total antioxidant capacity (T-AOC) assay. Test results confirmed that LMWF can enhance T-AOC by reducing reactive oxygen species (ROS) and oxidized low density lipoprotein (ox-LDL) levels and increasing glutathione peroxidase (GSH-Px) level in myocardium and liver tissues of AS mice. The results showed that LMWF and probucol had comparable antioxidant effects on AS, and when combined, no further antioxidant effect was achieved. [ABSTRACT FROM AUTHOR]

Saccharina japonica is a brown macroalga that has been commercially cultivated in China for almost a century. As a natural raw material, it is widely used in the food and pharmaceutical industries, and it may potentially be useful for biofuel production. However, little is known about the genes involved in carbohydrate biosynthesis, and their regulation is less understood. In this study, the analysis of growth traits and alginate and mannitol contents suggested that sporophyte development could be divided into four stages. Accordingly, we performed transcriptome analysis of the S. japonica sporophyte. In total, 589 million clean reads were generated, and 4,514 novel genes were identified. Gene expression analysis revealed that 2,542 genes were differentially expressed. Kyoto Encyclopedia of Genes and Genomes pathway enrichment analysis indicated that these genes were significantly enriched in "Carbon metabolism," "Photosynthesis," and "Photosynthesis‐antenna proteins" pathways, which are important for metabolism of various carbohydrates during sporophyte development. Systematic analysis identified the genes encoding enzymes for the biosynthesis of cell wall carbohydrates (including alginate, fucoidan, and cellulose) and cytoplasm storage carbohydrates (mannitol, laminarin, and trehalose). Among them, some key genes associated with carbohydrate content were further identified based on detailed expression profiling, representing good candidates for further functional studies. This study provides a global view of the carbohydrate metabolism process and an important resource for functional genomics studies in S. japonica. The results obtained lay the basis for elucidating the molecular mechanism of carbohydrate biosynthesis and for genetic breeding of carbohydrates‐related traits in kelp. [ABSTRACT FROM AUTHOR]

A total 68 types of marine algae oligosaccharides and polysaccharides were prepared and used to study the structure-activity relationship of oligosaccharides and polysaccharides in their interactions with fibroblast growth factors (FGF) 1 and 2. Factors considered include different types of algae, extraction methods, molecular weight, sulfate content and fractions. In the case of low molecular weight polysaccharide (SJ-D) from Saccharina japonica and its fractions eluting from anion exchange column, both 1.0 M NaCl fraction (SJ-D-I) and 2.0 M NaCl fraction (SJ-D-S) had stronger binding affinity than the parent SJ-D, suggesting that sulfated galactofucans represented the major tight binding component. Nuclear magnetic resonance showed that SJ-D-I was a typical sulfated galactofucan, composed of four units: 1, 3-linked 4-sulfated α-L-fucose (Fuc); 1, 3-linked 2, 4-disulfated α-L-Fuc; 1, 6-linked 4-sulfated β-D-Gal and/or 1, 6-linked 3, 4-sulfated β-D-Gal. Modification by autohydrolysis to oligosaccharides and desulfation decreased the FGF binding affinity while oversulfation increased the affinity. The solution-based affinities of SJ-D-I to FGF1 and FGF2 were 69 nM and 3.9 nM, suggesting that SJ-D-I showed better preferentially binding to FGF1 than a natural ligand, heparin, suggesting that sulfated galactofucan might represent a good regulator of FGF1. [ABSTRACT FROM AUTHOR]

A fucoidan (LJSF4) purified from Saccharina japonica was found to show a strong anti-inflammatory effect via activity assay in lipopolysaccharide (LPS) induced RAW 264.7 macrophage cells and zebrafish. Chemical and structural analysis indicated that LJSF4 with a sulfate content of 30.72% was composed of fucose, galactose, rhamnose, xylose and mannose with molar ratio percentages of 79.49%, 16.76%, 0.82%, 1.08% and 1.84%. NMR spectroscopy showed that LJSF4 is a polysaccharide with a backbone of alternating 1 → 3 linked α- l -fucopyranosyl and →4-α- l -fucopyranosyl with sulfate groups mainly at C–4 and partially at C–2 positions. Moreover, it also contained branches in the form of β- d -Galp-(1 → 4) units. The results of anti-inflammatory effect in vitro demonstrated that LJSF4 decreased the production of nitric oxide (NO) and cytokines, including TNF-α, IL-1β and IL-6. The mechanism revealed to be associated with the down-regulated expression of signal pathways including MAPK and NF-κB. By in vivo assay, LJSF4 showed a significantly protective effect by reducing the cell death rate, and the production of NO and ROS on LPS exposed zebrafish. Our results indicated that LJSF4 has the potential to be developed as an anti-inflammatory agent applied in functional food and cosmetic industries. • A novel fucose-rich fucoidan named as LJSF4 was purified from Saccharina japonica. • The chemical composition and structural characteristics of LJSF4 were investigated. • LJSF4 inhibited production of NO and pro-inflammatory mediators, and levels of iNOS, COX-2 on LPS-induced RAW 264.7 cells. • The mechanism of anti-inflammatory properties was associated with the suppression of NF-κB and MAPK signaling pathways. • LJSF4 showed significantly protective effect by reducing the production of NO and ROS in LPS-induced zebrafish. [ABSTRACT FROM AUTHOR]

Kelpak® is a seaweed extract from the phaeophyte, Ecklonia maxima, used to enhance growth and production of terrestrial plants. It is also beneficial for some red and green seaweeds. As such, we assessed if Kelpak® could enhance growth and thermal tolerance of the brown seaweeds, Saccharina latissima and S. angustissima. Juvenile sporophytes were dipped (30 or 60 min) in Kelpak® solutions of different concentrations (0.001, 0.005, 0.05, 1, and 5 ml L−1). These sporophytes were then cultivated in half‐strength PES at different temperatures (12, 16, 19, 23 and 25°C ± 1) for 20 days. The surviving sporophytes were then moved to 18 ± 1°C and cultivated for 14 additional days. Results show that temperature was the main factor driving survival and growth. Both species exposed to the temperatures of 23 and 25°C died during the first 7 days. Furthermore, no significant differences were observed in growth of sporophytes at the temperatures of 12 and 16°C. Results also show that treated sporophytes exposed to 18°C, the sublethal temperature, particularly of S. angustissima showed a higher survival and overall vigor than nontreated sporophytes. These results indicate that Kelpak® may enhance thermal tolerance and growth of S. latissima and S. angustissima exposed to sublethal temperatures. [ABSTRACT FROM AUTHOR]

Mass mortality of the long line culture of the sea urchin Strongylocentrotus intermedius in summer, which is greatly associated with their disease, energy storage and resistant abilities, is the most serious problem for the development of the aquaculture. Here, a feeding experiment was conducted for ~ 9 weeks to investigate the survival, growth and gonadal development of small S. intermedius (~ 3 cm) fed either brown algae Sargassum horneri or Saccharina japonica. Subsequently, we assessed their resistant abilities via observing the behaviors of righting, tube feet extension and Aristotle's lantern reflex at both moderately elevated and acutely changed water temperatures. Sea urchins fed S. horneri showed significantly fewer diseased individuals and slower gonadal development than those fed S. japonica. Consistently, significantly greater Aristotle's lantern reflex occurred in sea urchins fed S. horneri at moderately elevated temperatures. These findings suggest that S. horneri has direct application potential as food for the long line culture of S. intermedius in summer because of the advantage in health, energy storage (avoid the energy loss caused by gonadal development at small body sizes) and resistance abilities. In comparison, sea urchins fed S. japonica outperformed those fed S. horneri for all experimental behaviors under the acutely changed water temperatures. These findings clearly suggest that S. intermedius fed S. japonica is more suitable for the areas with cold water mass in summer, because it can effectively avoid or reduce the negative impacts of acute changes of water temperature on sea urchins. The present study provides valuable information into the management of the long line culture of S. intermedius in summer. [ABSTRACT FROM AUTHOR]

A detailed understanding of physiological and reproductive processes in seaweeds has repeatedly proven to be an essential pre-requisite in the successful development of a sustainable industry. The prime example of this was the classical discovery of the "conchocelis"-phase of Pyropia (Porphyra) by Kathleen Mary Drew-Baker in 1949. Such elegant research proved to be pivotal to the development of a globally important "nori" industry which transitioned from the simple provision of the enhanced surface area of the substrata for spore settlement to the sophisticated, mechanized and computerized operations in modern hatcheries supplied by seedling banks of selected species and their cultivars. All of the pre-requisite knowledge was acquired through intensive applied research. However, not all solutions need to be high-tech; problems caused by epiphytes and contaminants have been achieved by exposing Pyropia nets periodically and was found to be effective. This protocol was achieved based on fundamental observations by farmers which were then complemented and refined by laboratory trials. Techniques must be adapted for site-specific differences, as abiotic factors such as water current and movement, surface seawater temperature, light regime and photoperiod, nutrients dispersion and water quality are interrelated, either positively or negatively, influencing seaweed productivity and the end-use of the biomass. Unfortunately, positive techniques that have been shown in vitro/silica can prove to be impractical once attempted at large-scale cultivation and/or the return on investment is not justified by the commercial value of the resultant seaweed biomass. This chapter presents a summary of how the judicious application of knowledge based on the eco-physiological processes of common seaweed species from tropical and cold-waters can assist the future development and scale-up of the global seaweed industry. [ABSTRACT FROM AUTHOR]

Saccharina japonica is one of the most important economic brown seaweeds. It is intensively cultivated on large scales in a number of Asian countries. The current annual, global production is about 8 million tons valued as about 4 million US dollars. Considerable efforts have been made to S. japonica in China since the 1950s on its cultivation. To further advance the cultivation of this species, detailed research of genetics and breeding studies are required. Recently, with the advancement of sequencing techniques, the genomics and comparative transcriptomics data were yielded, and quantitative trait locus (QTL) mapping has been conducted, along with genetic linkage maps constructed to this species. New strains have been bred and selected, with better characteristics, e.g. higher seawater temperature resistances and higher yields. In this review, we present the current status of genetic and breeding studies that have been performed to S. japonica in China, and provide guidelines for future developments in the areas of genetic selection and breeding for this species. [ABSTRACT FROM AUTHOR]

Understanding the physiological responses of kelp to environmental parameters is essential for the conservation of natural kelp beds and increased cultivation yield. We investigated the effects of photosynthetically active radiation (PAR) and temperature on photosynthesis of a subarctic edible brown alga, Saccharina sculpera (Laminariales), using pulse amplitude modulation (PAM)–chlorophyll fluorometry and optical dissolved oxygen sensors. Photosynthesis–PAR experiments at 8 °C, 15 °C, and 22 °C revealed the highest net photosynthetic rates at 22 °C. Values for compensation (Ec) and saturation (Ek) indicated a high affinity for a light environment that reflected the natural vertical habitat of this alga. The photosynthetic response of S. sculpera to temperature indicated that the optimum temperature for oxygenic photosynthesis ( K o p t G P ) was 22.9 °C, which was consistent with the highest seawater temperature in Japanese distribution range for this subarctic species. The alga survived for 168 h at 24 °C in darkness. Continuous 6 h exposure to PAR of 100 µmol (low) and 1000 µmol (high) photons m–2 s–1 at 8 °C, 15 °C, and 22 °C induced chronic photoinhibition in the alga, with greater declines in effective quantum yields of photosystem II (ΦPSII). Failure to recover Fv/Fm after dark acclimation at low and high PAR was observed, except for low PAR at 8 °C. The physiological performance of S. sculpera indicates an affinity for a low light environment. We expect that our results will lead to an improvement in aquaculture techniques through the regulation of cultivation depth. [ABSTRACT FROM AUTHOR]

This study was performed to explore acute toxicity of biologically synthesized gold nanoparticles (AuNPs) to a model organism Daphnia magna. Hence, using aqueous extract of marine macroalga Saccharina japonica, two AuNPs including SJ-AuNPs-72 (72.6 ± 43.8 nm) and SJ-AuNPs-10 (10.8 ± 2.8 nm) were synthesized. These AuNPs were characterized by different techniques such as UV-Vis spectrophotometry, transmission electron microscopy (TEM), dynamic light scattering (DLS), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), and energy-dispersive X-ray spectroscopy (EDX). The 48-h LC50 values of SJ-AuNPs-72 and SJ-AuNPs-10 to D. magna were 1.57 ± 0.07 and 2.69 ± 0.12 mg/L, respectively, showing greater toxicity of SJ-AuNPs-72. After exposure of daphnids to treatments, AuNPs were accumulated in gut tract, and lipid droplets under the Daphnia carapace were also observed. Whereas studies on toxicity of biosynthesized AuNPs are still scarce, the achievements of this work are helpful for understanding the toxicity of biosynthesized AuNPs to crustacean D. magna. [ABSTRACT FROM AUTHOR]

Kelp life‐cycle transitions are complex and susceptible to various (a)biotic controls. Understanding the microscopic part of the kelp's lifecycle is of key importance, as gametophytes form a critical phase influencing, among others, the distributional limits of the species. Many environmental controls have been identified that affect kelp gametogenesis, whose interactive effects can be subtle and counterintuitive. Here we performed a fully factorial experiment on the (interactive) influences of light intensity, light quality, and the Initial Gametophyte Density (IGD) on Saccharina latissima reproduction and vegetative growth of delayed gametophytes. A total of 144 cultures were followed over a period of 21 d. The IGD was a key determinant for reproductive success, with increased IGDs (≥0.04 mg DW · mL−1) practically halting reproduction. Interestingly, the effects of IGDs were not affected by nutrient availability, suggesting a resource‐independent effect of density on reproduction. The Photosynthetically Usable Radiation (PUR), overarching the quantitative contribution of both light intensity and light quality, correlated with both reproduction and vegetative growth. The PUR furthermore specifies that the contribution of light quality, as a lifecycle control, is a matter of absorbed photon flux instead of color signaling. We hypothesize that (i) the number of photons absorbed, independent of their specific wavelength, and (ii) IGD interactions, independent of nutrient availability, are major determinants of reproduction in S. latissima gametophytes. These insights help understand kelp gametophyte development and dispersal under natural conditions, while also aiding the control of in vitro gametophyte cultures. [ABSTRACT FROM AUTHOR]