Effects of low molecular weight polysaccharide from Sargassum thunbergii against palmitic acid-induced intracellular lipid accumulation in 3T3-L1 adipocyte and HepG2 cells

Low molecular weight polysaccharides can be isolated from Sargassum thunbergii(LMPST)and in vitro experiments were conducted to evaluate the inhibitory effects on lipids.Two natures of LMPST were attained from S.thunbergii and appraised their LMPST on palmitic acid(PA)induced lipid accretion in Hep G2,and 3T3-L1 cells.LMPST treatment lessened lipid deposition and intracellular free fatty acid and triglyceride intensities in PA-treated above mentioned cells.The mechanistic study publicized that LMPST2 significantly suppressed adipogenesis and stimulated the PA-treated 3T3-L1 cells occupied in the lipolysis pathway.Furthermore,in PA-treated Hep G2 cells,the free fatty acid oxidation was significantly increased by LMPST2.Given these constructive properties of LMPST2 from S.thunbergii,is a potential candidate for diminishing the intracellular lipids,and for a therapeutic agent in those conditions.

Anti-obesity effects of fucoidan from Sargassum thunbergii in adipocytes and high fat diet induced obese mice through inhibiting adipogenic specific transcription factor

The prevalence of obesity has increased and is a health concern worldwide.Due to the concerns regarding synthetic anti-obesity treatments,nowadays natural products become a trend.Previous studies proved that there is a potential to use marine algae as anti-obesity agents.Therefore,in this study,the lipid inhibitory effect of crude polysaccharide of amyloglucosidase-assisted hydrolysate from Sargassum thunbergii(STAC)and its fucoidan fractions(STAFs)on 3T3-L1 cells and high-fat diet(HFD)-induced obese mice were investigated.According to the results,the STAF3,showed the highest xylose content and exhibited significant inhibitory effects on lipid accumulation by downregulating adipogenic and lipogenic proteins in 3T3-L1 cells.Furthermore,oral supplementation with STAC significantly declined gain in body weight and fat weight,and serum lipid contents in an HFD-induced obesity mouse model.Structural and chemical characterizations demonstrated that puritied STAF3 has consistent surface morphology and small particle size,with similar structural characteristics as commercial fucoidan.Together,these results indicate that STAC and purified STAF3 from Sargassum thunbergia is a potent source to develop as ananti-obesity agents or functional food products to counter obesity.

鼠尾藻(Sargassum thunbergii)有性生殖过程与育苗

采用室内培养和野外实地观测的方法,研究了鼠尾藻的生长发育和有性生殖过程,并在此基础上进行了有性生殖人工育苗实验。结果表明,鼠尾藻在海水温度高于22℃时,生殖托开始发育,海水温度超过23℃以后,生殖托的生长速度加快,海水温度超过24℃时,生殖托生长速度最快并迅速成熟,在海水温度达到26℃时,观察到了卵的集中排放挂托现象。鼠尾藻卵的排放较为齐整且有一定的先后顺序,生殖托基部的卵最先排出,中部次之,最后是顶部,雄托排精时间要稍晚于雌托排卵时间。受精卵大约在受精1h后进行第一次细胞分裂,分裂面与长轴垂直,大约2h后进行第二次分裂,下端细胞的分裂面平行于第一次分裂方向,而上端细胞的分裂面则垂直,随后大约每2—4h细胞分裂一次。从卵挂托到幼胚脱落一般需要24—48h。观察发现,生殖窝不仅存在于生殖托上,在部分生殖枝上也有分布。在鼠尾藻的人工育苗的实验中,胚苗在苗帘上的生长状态良好。

我国沿海鼠尾藻(Sargassum thunbergii)遗传资源RAPD分析

采用RAPD分子标记技术分析了我国沿海五个海区(大连、威海、青岛、温州、福州)鼠尾藻种群的遗传多样性。从60条随机引物中筛选出21条引物,对五个鼠尾藻种群共150份DNA样本进行了扩增,共检测到207个有效位点,多态位点达89.5%,Nei基因多样性指数(H)为0.2966,Shannon信息指数(I)为0.4508;种群间的遗传分化系数(Gst)为0.6131,基因流(Nm)为0.3155。AMOVA分析表明Fst为0.6185。我国沿海鼠尾藻种群遗传多样性较低,遗传分化水平较高。

桑沟湾筏式养殖鼠尾藻(Sargassum thunbergii)的生长特性

2014年4–6月在桑沟湾海区进行鼠尾藻(Sargassum thunbergii)海上筏式养殖实验,分析了鼠尾藻在桑沟湾的生长特性,调查了藻体上的附着生物。结果显示,(1)鼠尾藻在桑沟湾海域生长迅速,水温为10–17℃时特定生长率最高,可达6.10%/d;根据特定生长率与水温的关系,获得了鼠尾藻的最佳生长温度为14.9℃;(2)5月10日开始有生殖托形成,水温达到20.4℃时,鼠尾藻生殖托大量成熟,并有放散;(3)养殖期间,鼠尾藻最大长度达187.05 cm,均长可达112.31 cm;干湿比由0.147(4月)上升至0.189(6月);每公顷产量可达43.95 t(湿重),相当于干重为8.25 t;(4)藻体上有大型附着生物16种,主要优势种为尖嘴扁颌针鱼鱼卵、玻璃海鞘和海绵;附着生物的生物量随着水温升高而增加。研究表明,海区的附着生物对鼠尾藻的生长影响不大,在桑沟湾大规模养殖鼠尾藻是可行的。

Improvement of the zygote utilization and reduction of the seedling loss in the early stage of seedling production of Sargassum thunbergii (Fucales, Phaeophyta)

Artificial seedling production of Sargassum thunbergii is an effective way to relieve pressure on natural resources.In order to improve the utilization of zygotes and reduce the loss of seedlings,studies on the characteristic of the zygotes release,the development of rhizoids,the attachment of germlings,and the influence of jet washing were conducted.Results show that the percent of zygotes released was increased with time in the first 60 h.The capacity of germlings attached to the substratum was significantly increased,especially coincident with the time of the new rhizoids emerged and elongated.The detachment rate of germlings significantly decreased with the delay of starting time of jet washing or the reduction of jet washing velocity.However,the jet washing at any level applied in the experiment could cause considerable loss of germlings within the 20 days after the attachment.Our study provided some parameters to optimize the operation in the early stage of seedling production.

Comparative study of responses in the brown algae Sargassum thunbergii to zinc and cadmium stress

Heavy metal pollution in aquatic system is becoming a serious problem worldwide. In this study, responses of Sargassum thunbergii to dif ferent concentrations(0, 0.1, 0.5, 1.0 and 5.0 mg/L) of zinc(Zn) and cadmium(Cd) exposure separately were studied for 15 days in laboratory-controlled conditions. The results show that the specifi c growth rates increased slightly under the lower Zn concentration treatment(0.1 mg/L) at the first 5 d and then decreased gradually, which were significantly reduced with the exposure time in higher Zn concentrations and all Cd treatments compared to respective control, especially for 1.0 and 5.0 mg/L Cd. Chlorophyll a contents showed significant increase in 0.1 mg/L Zn treatment, whereas the gradually reduction were observed in the other three Zn treatments and all Cd treatments. The oxygen evolution rate and respiration rate presented distinct behavior in the Zn-treated samples, but both declined steadily with the exposure time in Cd treatments. The P/R value analyses showed similar variation patterns as chlorophyll a contents. Real-time PCR showed that lower Zn concentration(0.1 mg/L) increased mRNA expression of rbcL gene, whereas higher Zn concentrations and Cd reduced the rbcL expression. Taken together, these findings strongly indicate that Zn and Cd had different effects on S. thunbergii both at the physiological and gene transcription levels, the transcript level of photosynthesis-related gene rbcL can be used as an useful molecular marker of algal growth and environment impacts.

Phenological study of Sargassum thunbergii (Fucales, Phaeophyta) in Lidao Bay, Rongcheng, China

We conducted a phenological evaluation of Sargassum thunbergii, a common algal species, along the coast of Lidao Bay, Rongcheng, China. The local S. thunbergii population entered a maturation period from early June to mid-August, when seawater temperature was 14.4 to 25. 1℃. Our results suggest an increase in temperatttre and day length during this period initiated thalli maturation. Inhabitants of the low tidal zone had higher thalli length and biomass compared with those from the mid- and high tidal zones. We observed a switch in the length frequency distribution and contribution of length classes to biomass between the small （〈20 cm） and long （20-79.9 cm） length classes at the time of thallus maturity. This suggests there is a trade-off between sexual reproduction and vegetative regeneration.

Inhibitory effects and mechanisms of high molecular-weight phlorotannins from Sargassum thunbergii on ADP-induced platelet aggregation

We evaluated the effects of high molecular-weight phlorotannins from Sargassum thunbergii(STP) on ADP-induced platelet aggregation and arachidonic acid(AA) metabolism in New Zealand white rabbits and Wistar rats.The inhibition of STP on platelet aggregation was investigated using a turbidimetric method,and the levels of the terminal products of AA metabolism were measured using the corresponding kits for maleic dialdehyde(MDA),thromboxane B2(TXB2) and 6-keto-prostaglandin F1α(6-keto-PGF1α) by colorimetry and radioimmunoassay,as appropriate.We found that STP could inhibit ADP-induced platelet aggregation,and the inhibitory ratio was 91.50% at the STP concentration of 4.0 mg/mL.Furthermore,STP markedly affected AA metabolism by decreasing the synthesis of MDA(P<0.01) and increasing the synthesis of 6-keto-PGF1α,thus changing the plasma TXB2/6-keto-PGF1α balance when the platelets were activated(P<0.01).Therefore,STP altered AA metabolism and these findings partly revealed the molecular mechanism by which STP inhibits ADP-induced platelet aggregation.

鼠尾藻(Sargassum thunbergii)固碳能力对流速的响应

流动的海水可以为海藻的生长提供所需的营养物质,对其生长和繁殖起到了非常重要的作用,而当前的生理生态学模拟实验,大多忽略了这一重要的环境因子。大型海藻虽然被认为是第4类"蓝碳",但关于其固碳能力的研究较少。本研究设计了一种可以调节流速的大型海藻固碳能力测量系统,既可以测量大型海藻的净光合速率、呼吸速率和对无机氮、无机磷的吸收速率,也可以测量可溶性有机碳的释放速率。结果显示,与静止(0 m/s)相比,中流速(0.033 m/s)和高流速(0.094 m/s)均能提高鼠尾藻的净光合速率、净初级生产力、可溶性有机碳释放速率以及对无机氮、无机磷的吸收速率,且最大值均出现在高流速下。此外,鼠尾藻的可溶性有机碳释放速率随净初级生产力的提高而提高。本测量系统可为大型海藻固碳能力的研究提供切实可行的参考。

鼠尾藻(Sargassum thunbergii)对刺参生长及水环境的影响

研究了在一定养殖空间内刺参–鼠尾藻适宜的养殖容量和养殖密度。将不同密度的平均体重为(16.7±0.95)g的刺参和鼠尾藻混养在1 m3水体的塑料桶内,实验分为12组,每组设3个重复,对刺参、鼠尾藻的生长及养殖水环境因子的变化情况进行了研究与分析。结果显示,1)刺参、鼠尾藻平均日增重率(Mdwg)和特定生长率(SGR)受刺参密度和鼠尾藻密度影响显著(P<0.05)。作为对照,无鼠尾藻、刺参密度为750、500、250 g/m3时,其生长均相对较差;刺参密度为250 g/m3、鼠尾藻密度为1000、1500 g/m3时,刺参生长相对最好。刺参密度为750 g/m3、鼠尾藻密度为500 g/m3时,鼠尾藻特定生长率(SGR)最大;刺参密度为250 g/m3、鼠尾藻密度为1500 g/m3时,鼠尾藻特定生长率(SGR)最小;2)NH4+-N、NO2–-N、NO3–-N和PO4–-P含量变化受刺参和鼠尾藻养殖量的影响显著(P<0.05)。无鼠尾藻,刺参密度为750、500、250 g/m3时,实验组NH4+-N、NO2–-N、NO3–-N和PO4–-P含量相对较高,其中,刺参为750 g/m3实验组含量最高;刺参密度为250 g/m3、鼠尾藻密度为1000、1500 g/m3时,实验组NH4+-N、NO2–-N、NO3–-N和PO4–-P含量相对较低。研究结果显示,鼠尾藻密度的大小对促进刺参的生长有非常显著的影响,同时对养殖水体中的营养因子具有较强的吸收能力。本研究条件下,刺参密度为250 g/m3、鼠尾藻密度为1000、1500 g/m3模式参藻搭配比例较合适,其生态互利效果最好。

鼠尾藻(Sargassum thunbergii)对邻苯二甲酸二甲酯(DMP)胁迫的响应

邻苯二甲酸二甲酯(dimethyl phthalate,DMP)是近海环境有机污染物之一,不仅对海洋生物造成毒害,且能在生物体内富集和放大,对海洋生态系统形成严重威胁。本文以鼠尾藻(Sargassum thunbergii)为研究对象,通过测定比生长速率、叶绿素a含量、光合和呼吸速率、光合基因rbcL转录水平上的相对表达量等指标,研究了鼠尾藻对不同浓度DMP的响应。结果表明,低浓度的DMP(0.lmg/L)短时间内(≤15d)能促进鼠尾藻的生长和叶绿素a的合成,并使藻体的光合作用增强,诱导光合基因rbcL的表达,而在高浓度DMP(≥0.3mg/L)的作用下,鼠尾藻的生长速率、光合和呼吸速率、rbcL基因的表达量均随着暴露时间的延长呈明显下降趋势,且DMP浓度越高,降幅越大。以上研究结果对了解DMP对鼠尾藻胁迫的影响机制奠定了基础,为保护海洋经济藻类的养殖环境提供了理论依据。

Impact of Environmental Factors on the Photosynthesis and Respiration of Young Seedlings of <i>Sargassum thunbergii</i>(Sargassaceae, Phaeophyta)

Sargassum thunbergii is of great economic and ecological value to sea cucumber cultures and seaweed beds. However, studies on photosynthesis and respiration of S. thunbergii are limited. In this study, a liquid-phase oxygen electrode system and a chlorophyll fluorescence spectrometer were used to determine the photosynthetic characteristics of S. thunbergii seedlings at various light intensities, temperatures, and salinities. The light-saturated net photosynthetic rates, light saturation points, and respiratory rates of germlings were investigated. Results showed that the increase in rate of light saturation point was slow in the first 4 d, rapidly increased from 5 d to 9 d, and then gently increased at the final few days of the 15 d indoor culture period. The photosynthetic rate or respiratory rate of the seedlings rapidly and significantly decreased when the temperature was °C or >28°C. Short-term high- or low-salinity shock had significant effect on the photosynthetic and respiratory rates of the seedlings, specifically at 10 and 50 psu. However, the photosynthetic and respiratory rates recovered to the normal levels after 24 h of recovery period, which demonstrated a powerful ion-transport system of the seedlings. These results provided reference for the artificial breeding of S. thunbergii.

Reproductive Biology of <i>Sargassum thunbergii</i>(Fucales, Phaeophyceae)

Sargassum thunbergii is an economically important brown alga that is used as a perferred food for sea cucumber in China. However, reports on the reproductive biology of S. thunbergii are limited. This study observed the characteristics of mature receptacles. The effects of different temperatures, light intensities, and photoperiods on the egg release of mature S. thunbergii receptacles were investigated. A liquid-phase oxygen electrode system was used to obtain light saturation and light compensation points of egg and young thalli of S. thunbergii. Results showed that temperature was the key factor for the egg release of mature receptacles. The conditions most conducive to egg release were 20&degC to 23&degC temperature and 50 μmol photons m-2&middots-1 to 200 μmol photons m-2&middots-1 light intensity. In addition, the light saturation and compensation points of unfertilized eggs or young thalli at 2 d or 3 d postfertilization ranged from 90 μmol photons m-2&middots-1 to 120 μmol photons m-2&middots-1 and 14 μmol photons m-2&middots-1 to 22 μmol photons m-2&middots-1, respectively. The combined results provide a reference for the sporeling culture of S. thunbergii.

Comparative Studies on the Allelopathic Effects of Ulva pertusa Kjellml, Corllina pilulifera Postl et Ruprl, and Sargassum thunbergii mertl O. Kuntze on Skeletonema costatum （Grev.）Cleve

In the present study, we evaluated the allelopathic effects of three macroalgae, namely Ulva pertusa Kjellml, Corallina pilufifera Postl et Ruprl, and Sargassum thunbergii Mertl O. Kuntze, on the growth of the microalga Skeletonema costaturn （Grev.） Creve using culture systems in which the algae coexisted. The effects of the macroalgal culture medium filtrate on S. costatum were also investigated. Moreover, isolated co-culture systems were built to confirm the existence of allelochemicals and preclude growth inhibition by direct contact. The coexistence assay data demonstrated that the growth of S. costaturn was strongly inhibited when fresh tissues, dry powder and aqueous extracts were used; the allelochemicals were lethal to S. costatum at relatively higher concentrations. The effects of the macroalgal culture medium filtrate on the microalga showed both species specificity and complexity. The inhibitory effect of fresh macroalgal tissue and culture medium filtrate on the microalga was due to the alleochemicals released by the macroalgae. The results of the present study show that the allelopathic effects of macroalgae on the microalga are complex. The present study could shed light onto the basis of the interaction between macro- and microalgae.

Isolation of fucoxanthin from Sargassum thunbergii and preparation of microcapsules based on palm stearin solid lipid core

The objective of this study was to isolate fucoxanthin from Sargassum thunbergii and develop microcapsules with palm stearin as the solid lipid core for stability and efficient oral delivery of fucoxanthin. The microcapsules had smooth surfaces with the volume weighted mean diameter （d4.3） of 19.19 μm. Encapsulation efficiency and loading capacity of microcapsules with fucoxanthin were 98.3% and 0.04%, respectively. Moreover, the fucoxanthin in microcapsules presented higher stability than free fucoxanthin against light, humidity and temperature. Especially, the retention rates of fucoxanthin encapsulated in microcapsules reached 97.20% at 4℃, 92.60% at 25℃, 92.32% with the relative humidity of 33% and 92.60% in the dark. The cumulative amount of fucoxanthin released from microcapsules was 22.92% in simulated gastric fluid （SGF） and 56.55% in simulated intestinal fluid （SIF）.

固定化鼠尾藻Sargassum thunbergii对水中重金属锌的生物吸附效应

采用海藻酸钠-聚乙烯醇联合固定鼠尾藻与活性炭的方法对废水中重金属Zn^(2+)进行生物吸附研究。结果表明:当固定化材料配比为15 g·L^(-1)鼠尾藻粉,2%海藻酸钠溶液、6%聚乙烯醇溶液,1.5%活性炭时,固定化小球对废水中Zn^(2+)的吸附率最大。溶液在不同环境因素条件下吸附率不同,吸附率随着pH升高而升高,当pH为6时吸附率达到最大,随后开始下降;当温度为30℃,投放量为60 g·L^(-1)时吸附率上升至最大值后趋于平衡,吸附率不再随着条件的增加而增加;前30min吸附过程为快速吸附阶段,并在60 min后吸附率趋于平衡。在实验室规模的流化生物反应器中,固定化颗粒可以连续高效处理模拟矿山废水,同时经过多次吸附解吸循环后仍然具有较好的吸附效果,为固定化鼠尾藻的实际应用奠定了基础。

鼠尾藻生殖托不同生长阶段的附生细菌多样性研究

为探明雌雄异株大型海藻——鼠尾藻(Sargassum thunbergii)生殖组织附生细菌群落结构是否随生殖组织的生长而发生相应变化,本研究通过高通量测序技术对鼠尾藻生殖托不同生长时期的附生细菌群落进行了分析。结果显示:变形菌门(Proteobacteria)和拟杆菌门(Bacteroidetes)是其核心菌门,与其他大型海藻附生细菌的组成类似;α多样性分析显示鼠尾藻生殖托生长初期阶段的附生细菌群落均匀程度更高;β多样性分析显示鼠尾藻生殖托附生细菌群落在不同生长阶段存在显著差异,且性别可能是影响鼠尾藻生殖托附生细菌群落结构组成的一个重要因素;线性判别分析效应量(Line discriminant analysis effect size, LEfSe)软件分析显示,鼠尾藻生殖托在生长初期、生长中期以及成熟期的附生微生物中分别包含11、15和4个可能与自身发育相关的生物标志物。本研究初步揭示了鼠尾藻生殖托附生细菌的多样性和复杂性,为今后精细刻画鼠尾藻藻体与其附生微生物之间相关作用的网络提供了基础数据,也为鼠尾藻的保护和利用提供了新的见解。

水杨酸对鼠尾藻抗高温逆性的影响

为探明鼠尾藻对高温胁迫的响应以及水杨酸对其抗高温逆性的影响,将4株野生藻体置于1000mL的锥形瓶中,在15℃(对照组)下培养及30℃(处理组)下分别加入0、1、5、50mg/L水杨酸培养3d,分析高温及水杨酸对鼠尾藻的生长速率、光合色素含量、叶绿素荧光参数、抗氧化系统和热休克蛋白(HSP)70基因表达的影响。试验结果显示:水杨酸处理可显著促进高温下鼠尾藻的生长,比生长速率,叶绿素a、叶绿素c和类胡萝卜素的含量均随水杨酸质量浓度的升高先升后降,5mg/L水杨酸对生长的促进最为明显,比生长速率较高温胁迫组增加了589%,叶绿素荧光参数最大光化学量子产量有所升高,非光化学淬灭显著回升,超氧化物歧化酶和过氧化氢酶活性显著增强;HSP70基因的表达量在高温下显著升高,1mg/L水杨酸处理进一步促进了HSP70基因的表达,而5mg/L和50mg/L的水杨酸处理则抑制了高温下HSP70基因的表达。试验结果可为鼠尾藻的规模化人工繁育与抗逆机理研究提供基础数据。

ELEMENT COMPOSITION OF SARGASSUM THUNBEGII

Results of neutron activation analysis (NAA) of Sargassum samples collected from the Qingdao Taipingjiao coast on March 20 , 1996 showed that (1) Sargassumthunbergii can to some extent potassium and calcium (the accumulation coefficientwas 10), (2) it can accumulate all trace elements , especially iron , manganese and zinc,(3) it can accumulate strontium , aluminium thorium , and rare earth elements.