Tocopherol content of seaweed and seaweed meal. 3. Influence of processing and storage on the content of tocopherols, carotenoids, and ascorbic acid in seaweed meal.
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Animal Feed↗
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Suppression of 125I-uptake in mouse thyroid by seaweed feeding: possible preventative effect of dietary seaweed on internal radiation injury of the thyroid by radioactive iodine.
We conducted an animal experiment to determine how dietary seaweeds rich in iodine and dietary fibers suppress radioactive iodine uptake by the thyroid, using mice and four kinds of experimental diets, three with 1% or 2% powdered fronds of the kelp Laminaria religiosa and 2% powdered laver Porphyra yezoensis, and one with cellulose. Iodine content of a hot-water extract of the kelp was 0.530 +/- 0.001%, and its dietary fiber (DF) values were 52.8 +/- 1.2%. Iodine in an extract of the laver was 0.008 +/- 0.001%, and its DF values were 41.4% +/- 0.7%. A statistically significant reduction of 125I uptake by the thyroid, 3 hours after intragastric administration of the radionuclide at a dosage of 18.5 kBq or 185 kBq in 0.3 ml aqueous solution per mouse, was observed in mice previously fed the experimental diets containing 1% and 2% kelp during periods varying from 24 hours to 7 days. The degree of the suppression was observed to depend on the amount of iodine in the diet or in the injected sample, no matter whether organic or inorganic, judging from the results of an additional experiment. Thus, we conclude that previously fed iodine-rich material, especially dietary seaweeds rich in iodine and other minerals, vitamins, and beta-carotene, such as kelps or laver supplemented with inorganic iodine, may be effective in prevention of internal radiation injury of the thyroid.
Administration, Oral↗
Influences of seaweeds on metabolism of cholesterol and anticoagulant actions of seaweeds.
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Animals↗
Biotransformation and accumulation of arsenic in soil amended with seaweed.
For many coastal regions of the world, it has been common practice to apply seaweed to the land as a soil improver and fertilizer. Seaweed is rich in arsenosugars and has a tissue concentration of arsenic up to 100 micro/g g(-1). These arsenic species are relatively nontoxic to humans; however, in the environment they may accumulate in the soil and decompose to more toxic arsenic species. The aim of this study was to determine the fate and biotransformation of these arsenosugars in soil using HPLC-ICP-MS analysis. Data from coastal soils currently manured with seaweeds were used to investigate if arsenic was accumulating in these soils. Long-term application of seaweed increased arsenic concentrations in these soils up to 10-fold (0.35 mg of As kg(-1) for nonagronomic peat, 4.3 mg of As kg(-1) for seaweed-amended peat). The biotransformation of arsenic was studied in microcosm experiments in which a sandy (machair) soil, traditionally manured with seaweed, was amended with Laminaria digitata and Fucus vesiculosus. In both seaweed species, the arsenic occurs in the form of arsenosugars (85%). The application of 50 g of seaweed to 1 kg of soil leads to an increase of arsenic in the soils, and the dominating species found in the soil pore water were dimethylarsinic acid (DMA(V)) and the inorganic species arsenate (As(V)) and arsenite (As(III)) after the initial appearance of arsenosugars. A proposed decomposition pathway of arsenosugars is discussed in which the arsenosugars are transformed to DMA(V) and further to inorganic arsenic without appreciable amounts of methylarsonic acid (MA(V)). Commercially available seaweed-based fertilizers contain arsenic concentration between 10 and 50 mg kg(-1). The arsenic species in these fertilizers depends on the manufacturing procedure. Some contain mainly arsenosugars while others contain mainly DMA(V) and inorganic arsenic. With the application rates suggested by the manufacturers, the application of these fertilizers is 2 orders of magnitude lower than the maximum permissible sewage sludge load for arsenic (varies from 0.025 kg ha(-1) yr(-1) in Styria, Austria, to 0.7 kg ha(-1) yr(-1) in the U.K.), while a direct seaweed application would exceed the maximum arsenic load by at least a factor of 2.
Arsenates↗
Suppressive effects of the extracts of Japanese edible seaweeds on mutagen-induced umu C gene expression in Salmonella typhimurium (TA 1535/pSK 1002) and tumor promotor-dependent ornithine decarboxylase induction in BALB/c 3T3 fibroblast cells.
Some of epidemiological data indicated that ubiquitous consumption of seaweeds in Japan may be a possible protective factor against some types of tumor. To analyse this problem, the authors studied the antimutagenic and antitumor promotion activities in methanol-soluble extracts of typical edible seaweeds which showed suppressive effects on 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indol (Trp-P-1)-induced umu C gene expression in SOS response of Salmonella typhimurium (TA 1535/pSK 1002) and 12-O-tetradecanoylphorbol-13-acetate (TPA)-dependent ornithine decarboxylase induction in BALB/c 3T3 fibroblast cells. Although eight varieties of edible seaweeds including chlorophyta, Phaenophyta and Rhodophyta showed significant antimutagenic and antipromotion activities, they expressed the activities different from each other. Among these seaweeds, Enteromorpha prolifera ('Sujiaonori' in Japanese) and Porphyra tenera ('Asakusanori') showed relatively strong suppressive activities in both antimutagenic and antipromotion assays compared with other seaweeds. These seaweeds contained considerable amounts of beta-carotene as a possible active principle with anticarcinogenic activity. This compound was partially associated with the antimutagenic activity in the seaweed extract, but did not contribute to the antipromotion activity of seaweed extract under our experimental conditions. These results strongly suggest that Japanese edible seaweeds have possible antimutagenic and antipromotion activities probably associated with antitumor activity.
3T3 Cells↗
Effect of fiber-rich brown seaweeds on protein bioavailability of casein in growing rats.
The effect of three subtropical fiber-rich brown seaweeds, Sargassum hemiphyllum (Turn.) C. Ag., Sargassum henslowianum C. Ag. and Sargassum patens Ag., on protein bioavailability of casein were evaluated by growing rats. The effect of the fiber-rich seaweeds was determined by comparing the net protein ratio (NPR), true protein digestibility (TD), nitrogen balance (NB), biological value (BV), net protein utilization (NPU), and fecal and urinary nitrogen loss of seaweed-based diet groups with those of the cellulose-based control group. There were no significant differences on NPR and urinary N loss in all diet groups. However, the values of TD (range 85.6-89.6%), BV (range 96.9-97.5%), NPU (range 83.5-86.8%) and NB (range 145-150 mg/rat/day) in all seaweed-based diet groups were significantly (p<0.05, one-way ANOVA, Tukey-HSD) lower than those of the control group. On the contrary, the fecal weight (range 5.59-6.30 g/rat/day) and fecal nitrogen (N) loss (range 31.1-41.2 mg/rat/day) of rats fed seaweed-based diets were significantly (p<0.05, one-way ANOVA, Tukey-HSD) higher than that of the control one. However, the differences on the body weight gain and weight of internal organs including liver, kidney and spleen between the seaweed-based diets and control groups were insignificant except that the weight of caecum of rats fed seaweed-based diets was significantly (p<0.05, one-way ANOVA, Tukey-HSD) higher than that of control group. The possible mechanism of fiber-rich brown seaweeds in affecting the protein bioavailability of casein and their related nutritional implications were discussed.
Animals↗
B cell stimulating activity of seaweed extracts.
The activity of seaweed extracts on murine and human lymphocytes was studied in vitro. The extracts of some kind of seaweed, such as Hizikia fusiformis and Meristotheca papulosa, stimulated normal mouse spleen cells to proliferate. The responder cells are B cells, because the response was depleted by the treatment of spleen cells with anti-immunoglobulin (Ig) antibody and complement and being passed through a nylon wool column. This response is not due to lipopolysaccharide (LPS) contamination, because seaweed extracts can stimulate spleen cells of C3H/HeJ mice which are LPS low responders. Seaweed extracts also enhanced Ig production by B cells and tumor necrosis factor (TNF) production by macrophages. Furthermore, seaweed extracts stimulated human lymphocytes to proliferate. All these B cell stimulating activities of seaweed extracts associated with glycoproteins whose molecular weights resided in 100 kD. These results suggest that seaweed extracts have stimulating activity on B cells and macrophages and this ability could be clinically for the modulation of immune responses.
Animals↗
Effect of dietary Laminaria angustata (brown seaweed) on azoxymethane-induced intestinal carcinogenesis in male F344 rats.
The effect of dietary Laminaria angustata (brown seaweed) on azoxymethane (AOM)-induced intestinal carcinogenesis was studied in male F344 rats. Five-week old rats were fed semipurified diets containing 0 and 10% seaweed. When the rats were 7 weeks old, all except the vehicle-treated groups received weekly subcutaneous injections of AOM in normal saline for two weeks (20 mg/kg body wt/week). All animals were fed the experimental diets until the termination of the experiment, which was 28 weeks after the last AOM injection. The incidence (percent of animals with tumors) and multiplicity (tumors/animal) of small intestinal tumors did not differ significantly between the control and seaweed groups. The incidence and multiplicity of colon adenomas along with the size of colon tumors were increased in rats fed the seaweed diet compared with those fed the control diet. Dietary seaweed had no major effect on the concentration of fecal bile acids; however, the concentration of fecal cholesterol and total neutral sterols was decreased in the seaweed group. These results suggest that dietary seaweed increases the risk for colon tumors.
Adenocarcinoma↗
Are the reductions in nematode attack on plants treated with seaweed extracts the result of stimulation of the formaldehyde cycle?
Soil application to the roots of tomato plants (Lycopersicon esculentum) of a commercially-available alkaline extract of the brown alga, Ascophyllum nodosum, resulted in a significant reduction in the number of second-stage juveniles of both Meloidogynejavanica and M. incognita invading the roots, compared to those of plants treated with water alone. Egg recovery from the seaweed extract treated plants was also significantly lower. The three major betaines found in the seaweed extract (gamma-aminobutyric acid betaine, delta-aminovaleric acid betaine and glycinebetaine) also led to significant reductions in both the nematode invasion profile and egg recovery when applied at concentrations equivalent to those present in the extract. This led to the conclusion that the betaines present in the seaweed extract play a major role in bringing about the observed effects. Treatment of Arabidopsis thaliana plants with seaweed extract also resulted in a significant decrease in the number of females of M. javanica which developed in the roots. Significant reductions in egg recovery were also achieved from plants treated with the seaweed extract and similar effects were produced with the betaines found in the seaweed extract. As the experiments were conducted under monoxenic conditions, it can be concluded that the results obtained with the application of either the seaweed extract or betaines are not dependent on microorganisms associated with the rhizosphere.
Animals↗
Benthic macrofauna changes in areas of Venice lagoon populated by seagrasses or seaweeds.
Two areas of the Venice lagoon populated by seagrasses (three stations covered by Cymodocea nodosa (Ucria) Asherson, Zostera marina Linnaeus, Zostera noltii Hornemann) or seaweeds (two stations: one covered by Ulva rigida C. Agardh and another at present without seaweed biomass) were monitored by means of six surveys over a year in order to study macrofaunal composition and seasonal changes. The seagrass stations showed a mean species richness (28-30 S m(-2)), individual abundance (1854-4018 N m(-2)) and biomass (22.3-37.7 g m(-2) ash-free-dry-weight, AFDW) ca. 3-8 times higher than those populated by seaweeds (10-15 S m(-2), 494-1395 N m(-2) and 5.6-13.7 g m(-2) AFDW). Differences among seagrass or seaweed stations were much lower. The Ulva-dominated station showed a macrofauna completely different both from the other stations and the communities recorded ca. 30 years ago, before the prolific growth of Ulva. In this station, frequent biomass decompositions and anoxic crises created critical conditions for life favouring organisms with reduced life cycles, younger individuals and the epifaunal species instead of the infaunal ones. In particular, Ulva grazers and scrapers such as Gammarus aequicauda Stock and Gibbula adriatica Philippi were found to be by far the most abundant species, whereas the taxa characteristic of the associations found in the past, in the presence of seagrasses or seaweeds and typical of low eutrophicated environments, appear strongly reduced. Marked differences in the macrophyte dominance and in the bio-physico-chemical variables which characterise the main environmental conditions of the Venice lagoon support the different distribution and composition of macrofaunal communities. Seaweed stations appear mainly governed by the seasonal cycles of these un-rooted macrophytes which, by alternating periods of production and decomposition, are responsible for the drastic reduction of macrofauna biodiversity and biomass. Conversely, seagrass stations exhibit a better oxidisation of the environment and show conditions more favourable for macrofauna colonisation, especially in the presence of macrophytes which are characterised by very well developed below-ground systems such as Cymodocea nodosa.
Animals↗
Geographic and genetic variation in feeding preference for chemically defended seaweeds.
Genetic variation in tolerance for seaweed chemical defenses among populations of marine herbivores is poorly described, either because few marine studies have addressed the issue or because the feeding preferences of populations of marine herbivores rarely differentiate. We address this using the polyphagous amphipod Ampithoe longimana (Crustacea), which commonly consumes, and lives on, terpene-rich brown seaweeds in the tropical genus Dictyota. Previous work demonstrated that in areas where the amphipod and seaweeds overlap geographically, these chemically deterrent seaweeds provide the amphipod with spatial refuges from predation by omnivorous fishes that avoid consuming Dictyota. However, the amphipod's distribution extends northward of the seaweed's distribution, making this benefit of association unavailable to more northerly populations of amphipods. On average, populations sympatric with Dictyota have stronger feeding preference for Dictyota species and greater fitness when raised on Dictyota than do populations that are outside Dictyota's geographic endpoint. These results are consistent with the hypothesis that in areas where the amphipods co-exist with Dictyota, selection favors amphipods that tolerate Dictyota's chemical defenses and thereby access its enemy-free space. Amphipods allopatric with Dictyota are unable to tolerate Dictyota's chemical defenses, either because of selection, drift, or some mix of both forces. A trade-off between preference for Dictyota and for the chemically distinct seaweed Hypnea musciformis is suggested by the finding that populations with high preference for Dictyota tended to have lower preference for Hypnea. However, this population-level pattern appears to be the result of independent evolution and not a genetic trade-off: an analysis of full-sib families within a single population detected heritable variation in preferences for Dictyota and suggested this for Hypnea (although the latter was not statistically significant), yet no family-level covariation was detected. Phylogeographic analysis of mitocondrial DNA and nuclear sequences indicates a strong historical break between populations sympatric with Dictyota and populations more than 500 km beyond Dictyota's geographic endpoint. The historical separation of these most northerly populations could have allowed a random accumulation of alleles to effectively degrade tolerance for Dictyota, although selection may also be responsible for the degradation.
Amphipoda↗
Extraction and detection of arsenicals in seaweed via accelerated solvent extraction with ion chromatographic separation and ICP-MS detection.
An accelerated solvent extraction (ASE) device was evaluated as a semi-automated means of extracting arsenicals from ribbon kelp. The effect of the experimentally controllable ASE parameters (pressure, temperature, static time, and solvent composition) on the extraction efficiencies of arsenicals from seaweed was investigated. The extraction efficiencies for ribbon kelp (approximately 72.6%) using the ASE were fairly independent (< 7%) of pressure, static time and particle size after 3 ASE extraction cycles. The optimum extraction conditions for the ribbon kelp were obtained by using a 3 mL ASE cell, 30/70 (w/w) MeOH/H2O, 500 psi (1 psi = 7 KPa), ambient temperature, 1 min heat step, 1 min static step, 90% vol. flush, and a 120 s purge. Using these conditions, two other seaweed products produced extraction efficiencies of 25.6% and 50.5%. The inorganic species present in the extract represented 62.5% and 27.8% of the extracted arsenic. The speciation results indicated that both seaweed products contained 4 different arsenosugars, DMA (dimethylarsinic acid), and As(V). One seaweed product also contained As(III). Both of these seaweed products contained an arsenosugar whose molecular weight was determined to be 408 and its structure was tentatively identified using ion chromatography-electrospray ionization-mass spectrometry/mass spectrometry (IC-ESI-MS/MS).
Arsenicals↗
Statistical evaluation of ecosystem properties influencing the uptake of As, Cd, Co, Cu, Hg, Mn, Ni, Pb and Zn in seaweed (Eucus vesiculosus) and common mussel (Mytilus edulis).
In order to evaluate the influence of geographically varying marine ecosystem properties on the uptake of trace elements in bioindicators, samples were taken of seaweed (Fucus vesiculosus) and common mussel (Mytilus edulis) along the North Sea and Baltic Sea coast. Seasonal variations of the bioindicator status were minimized by sampling within 1 month. Ecosystem properties considered were the geographical position, the salinity and the concentrations of the macroelements Ca, Fe, K, Mg, Na, P and S in the bioindicators. Trace elements studied were As, Cd, Co, Cu, Hg, Mn, Ni, Pb and Zn. Factor analysis of the concentration patterns in the bioindicators and of salinity as a function of location confirmed the influence of the geographically varying salinity on the biological uptake of macroelements and trace elements. This influence of salinity was higher in the case of seaweed than in the case of mussel. Comparison of the geographical courses of the macroelement and trace-element concentrations by cluster analysis revealed corresponding courses for As and Hg in both bioindicators. All other elements showed different courses in seaweed and mussel. Subsequent cluster analysis comparing locations with respect to the macroelement or trace-element concentration patterns in the bioindicators, indicated a clear separation of North and Baltic Sea locations. However, the trace-element concentration patterns provided a regionally less distinctive ecosystem arrangement than those of the macroelement ones. The results of the cluster analysis were verified by discriminant analysis forming groups of locations with respect to geographical position and salinity. Results of discriminant analysis demonstrated, both for seaweed and for mussel as bioindicators, that the location groups formed according to the macroelement concentration patterns corresponded well with the geographical regions in the order of salinity. On the other hand, location groups based on the trace-element concentration patterns again showed a modified less distinctive ecosystem arrangement than the location groups based on macroelement concentration patterns. This confirms modified conditions for the uptake of trace elements in seaweed or mussel in comparison to the uptake of macroelements.
Animals↗
The rumen microbiology of seaweed digestion in Orkney sheep.
The microbial populations of the rumens of seaweed-fed and pasture-fed Orkney sheep were examined. The populations in the pasture-fed sheep were similar to those of other domestic ruminants fed on land plants, but those of the seaweed-fed animals showed major differences in the dominant species. Total ciliate populations were quantitatively similar, but in the seaweed-fed animals Dasytricha ruminantium was one of the most dominant species. No phycomycete fungi or cellulolytic bacteria were found in the seaweed-fed animals, and the bacterial population was dominated by Streptococcus bovis, Selenomonas ruminantium, Butyrivibrio fibrisolvens and lactate-utilizing species. Electron microscopy revealed that spirochaetes and an unidentified filamentous bacterium were probably of major significance in seaweed digestion. The ability of bacterial strains from both groups of animals to metabolize plant and algal constituents was examined.
Animals↗
Effect of processing on the microflora of Norwegian seaweed meal, with observations on Sporendonema minutum (Hoye) Frank and Hess.
Meal from the brown seaweed Ascophyllum nodosum (L.) Le Jol. is mainly used as an animal feed supplement. Since moist weed often develops a marked mold growth and since little was known about the microflora of seaweed meal, a cultural procedure was developed to enumerate the populations of bacteria, yeasts, and molds of seaweed meals manufactured by different drying processes. The microflora could be supported by a variety of media varying in levels of nutrition and in the source and concentration of salts. Fresh weed contained less than 10(3) bacteria and less than 10(2) yeasts and molds per g (dry weight). The type and extent of microbial populations in seaweed meal appeared to be dependent upon the method of seaweed drying. Rotary drum-drying at temperatures decreasing from 800 to 80 C maintained or reduced the microbial populations to 10(3) organisms per g (dry weight). Although meals with high nutritional quality can be obtained with warm air- or rock-dried weed, these conditions can also permit bacterial and mold development. Extended rock-drying in variable weather conditions and prolonged storage of moist weed, both of which decrease the nutritional quality, also lead to high bacterial numbers and to a marked development of the halophilic brown mold Sporendonema minutum which attained populations of 10(8) viable spores per g of dried weed. A poultry diet containing 5% badly molded weed had no apparent toxic or growth-depressing effect when fed to chicks.
Animal Nutritional Physiological Phenomena↗
[Nutritional evaluation and physiological effects of edible seaweeds].
A review concerning nutritional and physiological properties of edible seaweeds is presented. Seaweeds are traditionally consumed in Asia as sea vegetables, but in Western countries they have been used as sources of gelling or thickening agents. From a nutritional point of view, they are low-calorie foods, with a high concentration of minerals (Mg, Ca, P, K and I), vitamins, proteins and undigestible carbohydrates, and a low content in lipids. Quality of protein and lipid in seaweeds is acceptable comparing with other diet vegetables mainly due to their high content in essential amino acids and their relative high levels of unsaturated fatty acids. Dietary fiber content range from 33% to 75% of dry weight, and mainly consist of soluble polysaccharides (range from 17% to 59%). Seaweeds constitute a source of dietary fiber that differ chemically and physicochemically from those of land plants and thus may induce different physiological effects. Referenced data indicate that algal dietary fiber may show important functional activities, such as antioxidant, antimutagenic and anticoagulant effect, antitumor activity, and an important role in the modification of lipid metabolism in human body. In conclusion, seaweeds have a high nutritional value, therefore an increase in their consumption, would elevate the foods offer to population.
Food Handling↗
Expanding the scope of precision editing in seaweeds through the application of a novel CRISPR-associated nuclease 12a-aligned CRISPR system in Ulva prolifera.
Seaweeds, such as the fast-growing green alga Ulva prolifera, can be harnessed as valuable marine crops. The lack of scalable genome-editing tools hampers functional genomics to explore and elucidate algal molecular pathways with industrial importance. Here, we expanded precision genome modification in seaweeds by successfully demonstrating gene editing with a transgene-free AT-rich-targeting CRISPR-associated protein (Cas) system in U. prolifera. By evaluating various delivery buffers, comparing different Cas systems, and optimizing incubation temperatures, we determined suitable conditions for more widespread applicability of a novel Cas12a-aligned ST8 editor. We obtained >50 ST8-mediated knockout mutants of a toxin-based endogenous marker gene, UpAPT, at 28 °C post-delivery incubations. Our work diversified the applicable genome-editing tools in seaweeds, advancing algal functional genomics and providing more strategies to precisely target unexplored seaweed resources.
Ulva↗
Galactolipids rather than phlorotannins as herbivore deterrents in the brown seaweed Fucus vesiculosus.
The first investigation of seaweed chemical defense against herbivores involved the brown seaweed Fucus vesiculosus and suggested defense via phlorotannins. The first demonstration of seaweed induction of secondary metabolites in response to herbivory also involved the genus Fucus and assumed a defensive function for phlorotannins. Many other investigations correlate herbivore feeding preference with changing levels of phlorotannins in this genus and others, but few directly test the effects of phlorotannins. No studies have assessed Fucus chemical defenses using bioassay-guided separation to investigate the complete complement of compounds deterring herbivores. We investigated the deterrence of F. vesiculosus chemical extracts using herbivore bioassays to guide our chemical investigations. Although crude extracts from F. vesiculosus strongly deterred feeding by the sea urchin Arbacia punctulata, phlorotannins from this extract did not deter feeding at 2x or 4x natural concentration by dry mass. Feeding deterrence was due to: (1) a polar galactolipid in the ethyl acetate-soluble extract, and (2) a non-phenolic compound, or compounds, in the water-soluble extract. Although this is the first evidence of galactolipids deterring herbivores, such defenses could be geographically and taxonomically widespread. The galactolipid we discovered in Fucus occurs in marine dinoflagellates, and a related metabolite that deters herbivory has recently been discovered in a tropical green seaweed. We were unable to identify the second deterrent compound, but deterrence occurred in a fraction containing carbohydrates, including sulfated sugars, but no phlorotannins. Given the polarity of these chemical deterrents, they could co-occur with and confound bioassays of phlorotannins if investigators test phlorotannin-containing algal extracts without further purification.
Animals↗