Potential Anti-Aging Substances Derived from Seaweeds

Aging is a major risk factor for many chronic diseases, such as cancer, cardiovascular disease, and diabetes. The exact mechanisms underlying the aging process are not fully elucidated. However, a growing body of evidence suggests that several pathways, such as sirtuin, AMP-activated protein kinase, insulin-like growth factor, autophagy, and nuclear factor erythroid 2-related factor 2 play critical roles in regulating aging. Furthermore, genetic or dietary interventions of these pathways can extend lifespan by delaying the aging process. Seaweeds are a food source rich in many nutrients, including fibers, polyunsaturated fatty acids, vitamins, minerals, and other bioactive compounds. The health benefits of seaweeds include, but are not limited to, antioxidant, anti-inflammatory, and anti-obese activities. Interestingly, a body of studies shows that some seaweed-derived extracts or isolated compounds, can modulate these aging-regulating pathways or even extend lifespans of various animal models. However, few such studies have been conducted on higher animals or even humans. In this review, we focused on potential anti-aging bioactive substances in seaweeds that have been studied in cells and animals mainly based on their anti-aging cellular and molecular mechanisms.     

Effects of mass and position of artificial fouling added to the upper valve of the mangrove oyster Crassostrea rhizophorae on its growth and survival

We ran an experiment on mangrove oysters Crassostrea rhizophorae to evaluate the effects of adding different masses of artificial fouling to the upper valve, either to the umbo region or the ventral edge of the shell. Growth and survival were quantified after a 30 d period in suspended culture in the La Restinga Lagoon, Venezuela. The artificial fouling was cement weighing 0.5, 1, 2 or 3 fold the mass of the upper valve. No fouling was added to a control group. Fouling mass, but not the position of the artificial fouling, affected growth in shell length. However, only the heaviest fouling (3 times the mass of the upper valve) had a significant effect. In contrast, there was no affect of either fouling mass or position on tissue growth. Finally, our data indicated that mortality could be affected by the position where we added artificial fouling (greater mortality when fouling was added to the ventral edge of the shell), but not by fouling mass. Our study indicates it is unlikely that the levels of natural fouling that develop on oysters in suspended culture would be sufficient to affect either growth or survival.     

The efficiency and condition of oysters and macroalgae used as biological filters of shrimp pond effluent

Current shrimp pond management practices generally result in elevated concentrations of nutrients, suspended solids, bacteria and phytoplankton compared with the influent water. Concerns about adverse environmental impacts caused by discharging pond effluent directly into adjacent waterways have prompted the search for cost‐effective methods of effluent treatment. One potential method of effluent treatment is the use of ponds or raceways stocked with plants or animals that act as natural biofilters by removing waste nutrients. In addition to improving effluent water quality prior to discharge, the use of natural biofilters provides a method for capturing otherwise wasted nutrients. This study examined the potential of the native oyster, Saccostrea commercialis (Iredale and Roughley) and macroalgae, Gracilaria edulis (Gmelin) Silva to improve effluent water quality from a commercial Penaeus japonicus (Bate) shrimp farm. A system of raceways was constructed to permit recirculation of the effluent through the oysters to maximize the filtration of bacteria, phytoplankton and total suspended solids. A series of experiments was conducted to test the ability of oysters and macroalgae to improve effluent water quality in a flow‐through system compared with a recirculating system. In the flow‐through system, oysters reduced the concentration of bacteria to 35% of the initial concentration, chlorophyll a to 39%, total particulates (2.28–35.2 µm) to 29%, total nitrogen to 66% and total phosphorus to 56%. Under the recirculating flow regime, the ability of the oysters to improve water quality was significantly enhanced. After four circuits, total bacterial numbers were reduced to 12%, chlorophyll a to 4%, and total suspended solids to 16%. Efforts to increase biofiltration by adding additional layers of oyster trays and macroalgae‐filled mesh bags resulted in fouling of the lower layers causing the death of oysters and senescence of macroalgae. Supplementary laboratory experiments were designed to examine the effects of high effluent concentrations of suspended particulates on the growth and condition of oysters and macroalgae. The results demonstrated that high concentrations of particulates inhibited growth and reduced the condition of oysters and macroalgae. Allowing the effluent to settle before biofiltration improved growth and reduced signs of stress in the oysters and macroalgae. A settling time of 6 h reduced particulates to a level that prevented fouling of the oysters and macroalgae.     

Tipping Points in Seaweed Genetic Engineering: Scaling Up Opportunities in the Next Decade

Seaweed genetic engineering is a transgenic expression system with unique features compared with those of heterotrophic prokaryotes and higher plants. This study discusses several newly sequenced seaweed nuclear genomes and the necessity that research on vector design should consider endogenous promoters, codon optimization, and gene copy number. Seaweed viruses and artificial transposons can be applied as transformation methods after acquiring a comprehensive understanding of the mechanism of viral infections in seaweeds and transposon patterns in seaweed genomes. After cultivating transgenic algal cells and tissues in a photobioreactor, a biosafety assessment of genetically modified (GM) seaweeds must be conducted before open-sea application. We propose a set of programs for the evaluation of gene flow from GM seaweeds to local/geographical environments. The effective implementation of such programs requires fundamentally systematic and interdisciplinary studies on algal physiology and genetics, marine hydrology, reproductive biology, and ecology.     

大型海藻基生物炭中多环芳烃分布特征及毒性评价

研究大型海藻基生物炭中多环芳烃（Polycyclic Aromatic Hydrocarbons,PAHs）分布特征及毒性可为其资源化利用提供重要的依据。该研究利用索氏提取结合气相色谱质谱法分析了不同热解温度（200、300、400、500和600 ℃）的大型海藻（瓦氏马尾藻（Sagassum vachellianum）、羊栖菜（Sargassum fusiforme）、鼠尾藻（Sargassum thunbergii）、带形蜈蚣藻（Grateloupia turuturu）、粗枝软骨藻（Chondria crassicaulis）及孔石莼（Ulva pertusa））基生物炭中16种PAHs含量并对其毒性进行评价。结果表明,大型海藻基生物炭中均能检出PAHs（总量浓度为78.2～2 244.2 μg/kg）,且其生成量整体随热解温度升高先增加后降低。大型海藻基生物炭中PAHs含量均低于欧洲生物炭标准（European Biochar Certificate,EBC,10.1版）规定的EBC-AgroOrganic等级限量值（4±2）mg/kg。大型海藻基生物炭中PAHs以2环和3环为主,4环PAHs在所有生物炭中均存在,而5环和6环PAHs仅在部分生物炭中被检出。此外,不同大型海藻基生物炭呈现各异的苯并[a]芘毒性当量浓度（BaP- Toxic Equivalence Quantity, TEQBaP）（0.196～46.151 μg/kg）,其TEQBaP不仅依赖于生物炭中PAHs含量还与其环数和类型分布有关。在生物炭修复效果且潜在环境风险相近的基础上,结合产率及热解温度耗能,可选择热解温度较低的生物炭材料,为大型海藻基生物炭制备与应用的优化提供重要指导。     

Fouling and predation; how do they affect growth and survival of the blacklip pearl oyster, Pinctada margaritifera, during nursery culture?

This paper reports on 5 experiments conducted to assess the effect of cleaning regime and predation on growth and survival of blacklip pearl oyster (Pinctada margaritifera) juveniles in north Queensland, Australia. P. margaritifera juveniles with a mean (±SE) dorso-ventral shell height (DVH) of 4.5 ± 0.1 mm were placed into plastic mesh trays and cleaned either every 4 or 8 weeks or left uncleaned for 16 weeks. Cleaning regime had a significant effect on growth and survival (P < 0.005). Lowest DVH (16.2 ± 1.0) was shown by oysters in uncleaned trays during 16 weeks compared to oysters in cleaned trays; however, there was no significant difference in DVH between oysters held in trays cleaned every 4 (19.4 ± 1.2) or 8 weeks (21.2 ± 0.8). In contrast lowest survival was shown by oysters held in trays that were cleaned every 4 weeks (30 ± 5%), but no differences were noted between oysters cleaned every 8 weeks (63 ± 4%) and oysters that were left uncleaned for 16 weeks (75 ± 8%). Predators of P. margaritifera in northern Australia included crabs, stomatopods, flatworms, gastropods and fish. The stomatopod, Gonodactylus falcatus, was the most destructive predator with individuals consuming in excess of 20 juvenile pearl oysters per week. The leather jacket, Paramonocanthus japonicus, did not kill pearl oysters, but trimmed the margin of oysters shells significantly reducing DVH when compared to control groups cultured without fish. Removing predators monthly had a significant effect on growth of pearl oysters compared to oysters in non-inspected trays; however monthly inspection of culture trays did not significantly improve oyster survival. This revised version was published online in August 2006 with corrections to the Cover Date.     

Do surrogates describe patterns in marine macroalgal diversity in the Recherche Archipelago,temperate Australia?

• 1. Surrogates aim to predict species diversity and to minimize sampling effort. Here the value of surrogates for marine macroalgae is tested.
• 2. Higher taxonomic levels and dominant taxa were evaluated as surrogates for detecting patterns in macroalgal species diversity (derived from species‐level biomass data) in the Recherche Archipelago, Western Australia.
• 3. Data were stratified by two island groups (inshore and offshore), three depth intervals (<10 m, 10–20 m, >20 m), and two exposures to wave energy. Correlations between similarity matrices from surrogate and species diversity data matrices were analysed using a modified Spearman rank correlation (r_s). The ability of surrogates to detect differences between exposures to wave energy was also investigated using analysis of similarity. Species diversity data were aggregated to higher taxonomic levels and were either fourth‐root or presence/absence (richness) transformed.
• 4. Species richness was the most consistent surrogate (r_s‐values>0.69, P=0.001). Genus‐level richness was also strongly correlated to species diversity in the Recherche Archipelago, except in depths <10 m where patterns in diversity were characterized by species turnover.
• 5. At offshore islands in depths 10–20 m and >20 m, family‐ and order‐level biomass data were suitable surrogates owing to the abundance of Alariaceae (Order Laminariales) represented by a single genus and species. Surrogates using biomass data from the orders Laminariales, Ceramiales, Dictyotales and Fucales were also successful at offshore islands in middle to deeper depths.
• 6. At inshore islands in depths 10–20 m and >20 m, genera from the orders Gigartinales, Fucales and Ceramiales were strongly correlated to species biomass data.
• 7. Surrogates, like species richness, that were strongly correlated to species biomass data were also able to distinguish between exposures to wave energy, based on analysis of similarity tests.
• 8. Sampling effort would be reduced if collecting richness data in species‐rich macroalgal assemblages such as those found in temperate Australia.

Copyright © 2006 John Wiley & Sons, Ltd.     

Profiling of the Molecular Weight and Structural Isomer Abundance of Macroalgae-Derived Phlorotannins

Phlorotannins are a group of complex polymers of phloroglucinol (1,3,5-trihydroxybenzene) unique to macroalgae. These phenolic compounds are integral structural components of the cell wall in brown algae, but also play many secondary ecological roles such as protection from UV radiation and defense against grazing. This study employed Ultra Performance Liquid Chromatography (UPLC) with tandem mass spectrometry to investigate isomeric complexity and observed differences in phlorotannins derived from macroalgae harvested off the Irish coast (Fucus serratus, Fucus vesiculosus, Himanthalia elongata and Cystoseira nodicaulis). Antioxidant activity and total phenolic content assays were used as an index for producing phlorotannin fractions, enriched using molecular weight cut-off dialysis with subsequent flash chromatography to profile phlorotannin isomers in these macroalgae. These fractions were profiled using UPLC-MS with multiple reaction monitoring (MRM) and the level of isomerization for specific molecular weight phlorotannins between 3 and 16 monomers were determined. The majority of the low molecular weight (LMW) phlorotannins were found to have a molecular weight range equivalent to 4–12 monomers of phloroglucinol. The level of isomerization within the individual macroalgal species differed, resulting in substantially different numbers of phlorotannin isomers for particular molecular weights. F. vesiculosus had the highest number of isomers of 61 at one specific molecular mass, corresponding to 12 phloroglucinol units (PGUs). These results highlight the complex nature of these extracts and emphasize the challenges involved in structural elucidation of these compounds.     

枸杞岛海藻场大型底栖无脊椎动物摄食类群研究

随着海洋生态学研究的深入和海洋环境监测的需要,一些传统的研究方法如多样性指数等在评价大型底栖生物群落结构变化时显得说服力不足,而摄食功能群的研究越来越受到重视。本实验根据2012年8月对浙江枸杞岛海藻场大型底栖无脊椎动物的调查实验,分析该海域夏季大型底栖无脊椎动物摄食类群的组成、空间及数量分布,并进行相关生态评价。结果表明,枸杞岛海藻场夏季大型底栖无脊椎动物组成以肉食者和滤食者占较大优势,食碎屑者、植食者和食底泥者次之,杂食者最少;肉食者的优势种为布尔小笔螺、寄居蟹、扁平管帽螺、甲虫螺和四齿矶蟹等,滤食者的优势种为条纹隔贻贝、带偏顶蛤、短石蛏和布氏蚶等,植食者的优势种为钩虾、单一丽口螺和锈凹螺等;各摄食类群水平分布较均匀,垂直分布受水深和摄食饵料的限制;基于大型底栖无脊椎动物功能类群的生态参数评价结果表明,枸杞岛海藻场大型底栖无脊椎动物群落健康状态呈虚弱水平,大部分站位大型底栖无脊椎动物群落受到轻度扰动,底栖生态质量状况较好。     

威海双岛海域人工鱼礁区大型海藻夏季群落结构变化

2013年6月和8月,采用潜水采样和录像的方法调查了威海双岛海域人工鱼礁区内礁石上附着的大型海藻,并分析了海藻群落组成与环境因子的关系.2次调查共采集到大型海藻9种,其中红藻门5种、褐藻门和绿藻门各2种.夏末和夏初的海藻群落相似度为20.35％,对相似性贡献最大的5种海藻分别为金膜藻(Chrysymenia wrightii)、日本异管藻(Hterosiphonia japonica)、扁江蓠(Gracilaria textorii)、海黍子(Sargassum muticum)和孔石莼(Ulvapertusa).夏末的海藻生物量密度(243.83 g/m2)高于夏初(164.99 g/m2),但覆盖率由64.53％～91.20％降至52.53％～72.53％(威海圣鲲礁区除外),绝对优势种由夏初的日本异管藻演替为夏末的金膜藻.根据主成分分析(PCA)和冗余分析(RDA)结果,影响海藻群落变化的环境因子中,前3位分别为水温、盐度和水底照度;夏末,由于水体透明度较低(＜2.0 m),光照条件可能成为海藻分布的限制因子.另外,夏末污损生物的大量出现在一定程度上影响了海藻的覆盖率.