Saccharina japonica Ethanol Extract Ameliorates Depression/Anxiety-Like Behavior by Inhibiting Inflammation, Oxidative Stress, and Apoptosis in Dextran Sodium Sulfate Induced Ulcerative Colitis Mice

Saccharina japonica is a common marine vegetable in East Asian markets and has a variety of health benefits. This study was focused on the anti-depressant/anxiety effects of Saccharina japonica ethanol extract (SJE) on dextran sodium sulfate (DSS)-induced mice and its potential mechanism in their brain. Male C57BL/6 mice were treated with mesalazine and various doses of SJE (1, 2, and 4 g/kg body weight) for 2 weeks, followed by DSS treatment at the second week. The DSS-induced mice showed depression/anxiety-like behavior, which included shorter path length in the open field test and longer immobility time in the tail suspension test. L-SJE alleviated the depression-like behaviors. In the DSS-induced mice, reduced synaptic plasticity activated microglia, increased proinflammatory cytokines, decreased anti-inflammatory cytokine, and increased expression levels of Toll-like receptors-4, nuclear factor kappa-B, NOD-like receptors 3, apoptosis-associated speck-like protein, and Caspase-1 were observed, most of which were alleviated by SJE treatment. Furthermore, all the SJE groups could significantly enhance superoxide dismutase activity, while the L-SJE treatment decreased the contents of malondialdehyde, and the H-SJE treatment inhibited apoptosis. All these results showed that the SJE might serve as a nutritional agent for protecting the brain in ulcerative colitis mice.

The potential of seaweed cultivation to achieve carbon neutrality and mitigate deoxygenation and eutrophication

Carbon neutrality has been proposed due to the increasing concerns about the consequences of rising atmospheric CO2. Previous studies overlooked the role of lost particle organic carbon (POC) and excreted dissolved organic carbon (DOC) from seaweed cultivation in carbon sequestration, that is to say, long term carbon storage in the oceanic sediments and in the water. This study assessed the potential of seaweed cultivation to achieve carbon neutrality of China by 2060 using a new method that included lost POC and excreted DOC. Based on the seaweed production in the years 2015-2019 in China, harvested seaweed removed 605,193 tonnes of carbon, 70,304 tonnes of nitrogen and 8,619 tonnes of phosphorus from seawaters annually; farmed seaweed sequestrated 343,766 tonnes of carbon and generated 2530,558 tonnes of oxygen annually. Among the seven farmed seaweeds, Gracilariopsis lemaneiformis has the highest capacities for carbon removal (9.58 tonnes ha-1 yr-1) and sequestration (5.44 tonnes ha-1 yr-1) and thus has the smallest cultivation area required to sequestrate 2.5 Gt CO2 that is annually required to achieve China's carbon neutrality goal by 2060. The O2 generated by seaweed cultivation could increase dissolved oxygen in seawaters (0-3 m deep) by 21% daily, which could effectively counteract deoxygenation in seawaters. Gracilariopsis lemaneiformis also has the highest N removal capacity while Saccharina japonica has the highest P removal capacity. To completely absorb the N and P released from the fish mariculture, a production level or a cultivation area two and three times larger (assuming productivity remains unchanged) would be required. This study indicates that seaweed cultivation could play an important role in achieving carbon neutrality and mitigating deoxygenation and eutrophication in seawaters. Cultivation cost could be offset to some extent by increased sales of the harvest parts of the seaweed for food and biofuel.

Breeding in the Economically Important Brown Alga Undaria pinnatifida: A Concise Review and Future Prospects

Undaria pinnatifida is the commercially second most important brown alga in the world. Its global annual yield has been more than two million tonnes since 2012. It is extensively cultivated in East Asia, mainly consumed as food but also used as feed for aquacultural animals and raw materials for extraction of chemicals applicable in pharmaceutics and cosmetics. Cultivar breeding, which is conducted on the basis of characteristics of the life history, plays a pivotal role in seaweed farming industry. The common basic life history shared by kelps determines that their cultivar breeding strategies are similar. Cultivar breeding and cultivation methods of U. pinnatifida have usually been learned or directly transferred from those of Saccharina japonica. However, recent studies have revealed certain peculiarity in the life history of U. pinnatifida. In this article, we review the studies relevant to cultivar breeding in this alga, including the peculiar component of the life history, and the genetics, transcriptomics and genomics tools available, as well as the main cultivar breeding methods. Then we discuss the prospects of cultivar breeding based on our understanding of this kelp and what we can learn from the model brown alga and land crops.

Sequential Hydrothermal HCl Pretreatment and Enzymatic Hydrolysis of Saccharina japonica Biomass

This study investigated the production of fermentable sugars from carbohydrate-rich macroalgae Saccharina japonica using sequential hydrolysis (hydrothermal acid pretreatment and enzymatic hydrolysis) to determine the maximum reducing sugar yield (RSy). The sequential hydrolysis was predicted by three independent variables (temperature, time, and HCl concentration) using response surface methodology (RSM). Enzymatic hydrolysis (8.17% v/wbiomass Celluclast® 1.5 L, 26.4 h, 42.6 °C) was performed after hydrothermal acid pretreatment under predicted conditions (143.6 °C, 22 min, and 0.108 N HCl concentration). Using this experimental procedure, the yields of hydrothermal acid pretreatment, enzymatic hydrolysis, and sequential hydrolysis were 115.6 ± 0.4 mg/g, 117.7 ± 0.3 mg/g, and 183.5 ± 0.6 mg/g, respectively. Our results suggested that sequential hydrolysis of hydrothermal acid pretreatment and enzymatic hydrolysis was more efficient than their single treatment.

Characterisation of the Genes Encoding Mannuronan-C5-Epimerase in the Brown Alga Lessonia Variegata

<p>Alginate is known to be a commercially valuable polysaccharide, of great importance in industries such as food, cosmetics, medicine and pharmaceuticals. It is obtained commercially by harvesting brown algae. The final step in the alginate biochemical pathway involves the epimerization of D-mannuronic residues into L-guluronic residues, catalyzed by the enzyme mannuronan-C5-epimerase. This final step has been found to be responsible for controlling the physicochemical properties of the produced alginate. This study is the first to characterize the genes encoding for the enzyme mannuronan-C5- epimerase in the Northern, Southern and Wellington lineages of the brown alga Lessonia variegata (Phaeophyceae). The gene of interest was amplified by standard PCR and cloning. Cloning PCR results revealed the presence of two distinct copies of the gene in Lessonia variegata. The coding region of the copies was found to be very conserved with very little sequence variation. The Lessonia variegata sequences were compared with those of Laminaria digitata and Saccharina japonica, which indicated that at least one gene duplication event has occurred in Lessonia variegata, leading to the formation of two gene duplicates. The possible mechanisms by which the gene paralogs may control the structure and function of the produced alginate have been discussed.</p>

Characterisation of the Genes Encoding Mannuronan-C5-Epimerase in the Brown Alga Lessonia Variegata

<p>Alginate is known to be a commercially valuable polysaccharide, of great importance in industries such as food, cosmetics, medicine and pharmaceuticals. It is obtained commercially by harvesting brown algae. The final step in the alginate biochemical pathway involves the epimerization of D-mannuronic residues into L-guluronic residues, catalyzed by the enzyme mannuronan-C5-epimerase. This final step has been found to be responsible for controlling the physicochemical properties of the produced alginate. This study is the first to characterize the genes encoding for the enzyme mannuronan-C5- epimerase in the Northern, Southern and Wellington lineages of the brown alga Lessonia variegata (Phaeophyceae). The gene of interest was amplified by standard PCR and cloning. Cloning PCR results revealed the presence of two distinct copies of the gene in Lessonia variegata. The coding region of the copies was found to be very conserved with very little sequence variation. The Lessonia variegata sequences were compared with those of Laminaria digitata and Saccharina japonica, which indicated that at least one gene duplication event has occurred in Lessonia variegata, leading to the formation of two gene duplicates. The possible mechanisms by which the gene paralogs may control the structure and function of the produced alginate have been discussed.</p>