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Quan Sheng Zhang - One of the best experts on this subject based on the ideXlab platform.
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Photoacclimation characteristics of Sargassum thunbergii germlings under different light intensities
Journal of Applied Phycology, 2014Co-Authors: Quan Sheng Zhang, Hong-liang LiuAbstract:The photosynthesis and growth responses of Sargassum thunbergii germlings to different light intensities (10, 60, and 300 μmol photons m−2 s−1) were investigated. Maximum photochemical efficiency (Fv/Fm), rapid light curves (RLCs), and photochemical and non-photochemical quenching (qP and NPQ) were estimated by a pulse amplitude-modulated fluorometer. The photosynthesis of S. thunbergii germlings exhibited different properties to optimize light capture and utilization. The excitation pressure (1 − qP) was rapidly increased to approximately 0.27 showing that germlings responded to high light by chronic photoinhibition with an accumulation of closed reaction centers, which ultimately resulted in a slow growth. This was accompanied by a reduced Fv/Fm with time and a development of high capacity for NPQ. Although Fv/Fm in moderate-light germlings did not fully recover overnight, germlings demonstrated a less severe chronic photoinhibition considering the reduced degree of excitation pressure accumulation of approximately 0.15. The relative stability of photosynthetic capacity (rETRmax, Ek, and α) could endow germlings with the highest relative growth rate (RGR) of approximately 9.3 % day−1 in moderate light. By contrast, low-light germlings demonstrated high Fv/Fm and Fo, corresponding high α collectively suggested greater efficiency of light absorption and energy transformation. Sustained increases in electron transport capacity (rETRmax and Ek) occurred in low-light germlings, which resulted in a stable RGR of over 8.2 % day−1. Consequently, S. thunbergii germlings are considered to prefer low light regimes and have a relative capacity of moderate and high light tolerance. However, the light acclimation to oversaturating conditions is at the cost of slow growth to maintain survival.
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zygote derived seedling production of Sargassum thunbergii focus on two frequently experienced constraints in tank culture of seaweed
Journal of Applied Phycology, 2012Co-Authors: Quan Sheng Zhang, Shu Bao Zhang, Zhi Cheng Lu, Shao Hua Cu, Yong-zheng Tang, Yong Qiang YuAbstract:Mass collection of germlings and growth of fouling algae are two main constraints for the seedling production of Sargassum thunbergii. In this study, 65% and 40% of reproductive output (allocation of biomass to sexual reproductive tissue) for farmed and natural populations respectively, were recorded during peak reproduction. In terms of germlings per kilogram wet weight of plants, the farmed population gave a higher yield than the natural population (3.2 × 105 and 1.2 × 105 germlings kg-1, respectively). These results indicate that farmed populations could be used as parental plants for germling collection in seedling production. During the experiment, fouling was controlled by jet washing and high-density seeding. A germling detachment of less than 10% was observed when, after 48 h of attachment, collectors were jet-washed with an intensity of 1 kg cm-2. High-density seeding had adverse effects on length mean, size equality, and occurrence of branches of germlings. However, 30–50 individuals cm-2 are thought to be usable in the seedling production of S. thunbergii because of less density effects. Seedlings of > 0.5 cm length could be achieved after 1 month of tank culture.
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tolerance of Sargassum thunbergii germlings to thermal osmotic and desiccation stress
Aquatic Botany, 2012Co-Authors: Shaohua Chu, Quan Sheng Zhang, Yong-zheng Tang, Shikai Liu, Shu Bao ZhangAbstract:Abstract The construction of artificial seaweed beds in the intertidal zone is a challenge due to extreme levels of physical stress. In order to provide a basis for the construction using the dispersal of microscopic juveniles, a three-way factorial experimental design was used to evaluate the tolerance of Sargassum thunbergii germlings shortly released from fertile thalli to temperature, salinity and desiccation in this study. Results revealed that temperature, salinity and desiccation significantly affected the growth and survival of germlings. Germlings showed rapid growth with relative growth rate (RGR, % day −1 ) over 16% when cultured at 25 °C and full immersion in normal seawater. Although growths of germlings subjected to moderate conditions were significantly inhibited, RGRs over 13% were obtained. The RGRs of germlings below 10% were observed only at 35 °C and 9 h desiccation treatments. In comparison to growth, survival was less affected by physical stress. Germlings showed low mortalities below 10% under appropriate conditions (25 °C and 30 °C combined with full immersion), and below 60% under moderate conditions, by the end of experiment. However, the mortality rates increased to over 90% under extreme conditions (9 h desiccation and 35 °C combined with full immersion in salinity of 12). These results showed that S. thunbergii germlings had high tolerance to physical stresses. In addition to the main effects, both two-way and three-way interactions between temperature, salinity and desiccation were significant. Based on the magnitude of effect, desiccation was the predominant factor affecting both growth and survival. According to the results, construction of artificial tanks in natural habitat to minimize desiccation may be an effective strategy for S. thunbergii restoration using germlings.
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Trade-off between vegetative regeneration and sexual reproduction of Sargassum thunbergii
Hydrobiologia, 2011Co-Authors: Shaohua Chu, Quan Sheng Zhang, Shu Bao Zhang, Shikai Liu, Yong-zheng TangAbstract:An ecological demographic study was conducted from January to December 2009 at Changshan Island on the northern side of Shandong Peninsula, China. The study investigated stem regeneration and the resource trade-off between sexual reproduction and vegetative regeneration of the brown alga Sargassum thunbergii at the individual thallus level. Stem regeneration from the holdfast occurred year round but with significant seasonality, peaking in the early summer. Both percentage of fertile stems and reproductive effort were negatively correlated with stem regeneration in the middle and later periods of sexual reproduction. Furthermore, the correlation coefficients increased significantly with time. These observations suggested that an increase in resource allocation to sexual reproduction would lead to a decrease in allocation to vegetative regeneration during the reproductive period. Reproductive effort was lower and stem regeneration was higher in the wave-exposed location compared with the sheltered location, indicating that allocation of resources between sexual reproduction and vegetative regeneration varied with location. When reproductive tissues were removed, the number of new stems produced from holdfasts increased, and when new stems were removed, an increase in reproductive effort occurred. These results suggest that trade-off between sexual reproduction and vegetative regeneration occurs in S. thunbergii.
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Sexual reproductive allocation of Sargassum thunbergii at Taiping Cape of Yellow Sea
Ying yong sheng tai xue bao = The journal of applied ecology, 2011Co-Authors: Jinhua Pan, Quan Sheng Zhang, Xin Jiang, Zhuang-zhi Zhang, De-bin Wang, Houwei Han, Ru-zhou WangAbstract:This paper studied the dynamics of reproductive allocation (RA) of Sargassum thunbergii during its sexual reproductive season and the related environmental factors at the Taiping Cape of Yellow Sea. The sexual reproduction of S. thunbergii initiated in early June, peaked in mid July when the sea water temperature was about 22 degrees C (the mean proportion of biomass allocated to reproductive organs on July 19 was 76.7%), and ended in late August. The RA had a significant linear correlation with the average length of thallus branches (r = 0.855, P wave strength > tidal level x wave strength.
De-lin Duan - One of the best experts on this subject based on the ideXlab platform.
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Historical isolation and contemporary gene flow drive population diversity of the brown alga Sargassum thunbergii along the coast of China.
BMC evolutionary biology, 2017Co-Authors: Zhong-min Sun, Jian-ting Yao, Fu-li Liu, Pablo Fresia, De-lin DuanAbstract:Long-term survival in isolated marginal seas of the China coast during the late Pleistocene ice ages is widely believed to be an important historical factor contributing to population genetic structure in coastal marine species. Whether or not contemporary factors (e.g. long-distance dispersal via coastal currents) continue to shape diversity gradients in marine organisms with high dispersal capability remains poorly understood. Our aim was to explore how historical and contemporary factors influenced the genetic diversity and distribution of the brown alga Sargassum thunbergii, which can drift on surface water, leading to long-distance dispersal. We used 11 microsatellites and the plastid RuBisCo spacer to evaluate the genetic diversity of 22 Sargassum thunbergii populations sampled along the China coast. Population structure and differentiation was inferred based on genotype clustering and pairwise F ST and allele-frequency analyses. Integrated genetic analyses revealed two genetic clusters in S. thunbergii that dominated in the Yellow-Bohai Sea (YBS) and East China Sea (ECS) respectively. Higher levels of genetic diversity and variation were detected among populations in the YBS than in the ECS. Bayesian coalescent theory was used to estimate contemporary and historical gene flow. High levels of contemporary gene flow were detected from the YBS (north) to the ECS (south), whereas low levels of historical gene flow occurred between the two regions. Our results suggest that the deep genetic divergence in S. thunbergii along the China coast may result from long-term geographic isolation during glacial periods. The dispersal of S. thunbergii driven by coastal currents may facilitate the admixture between southern and northern regimes. Our findings exemplify how both historical and contemporary forces are needed to understand phylogeographical patterns in coastal marine species with long-distance dispersal.
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Additional file 9: Figure S3. of Historical isolation and contemporary gene flow drive population diversity of the brown alga Sargassum thunbergii along the coast of China
2017Co-Authors: Zhong-min Sun, Jian-ting Yao, Fu-li Liu, Pablo Fresia, De-lin DuanAbstract:UPGMA tree of 22Â Sargassum thunbergii populations based on microsatellites. (DOCX 53 kb
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Additional file 5: Table S4. of Historical isolation and contemporary gene flow drive population diversity of the brown alga Sargassum thunbergii along the coast of China
2017Co-Authors: Zhong-min Sun, Jian-ting Yao, Fu-li Liu, Pablo Fresia, De-lin DuanAbstract:Pairwise differentiation of 22Â Sargassum thunbergii populations base on microsatellites. (DOCX 18 kb
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Additional file 1: Table S1. of Historical isolation and contemporary gene flow drive population diversity of the brown alga Sargassum thunbergii along the coast of China
2017Co-Authors: Zhong-min Sun, Jian-ting Yao, Fu-li Liu, Pablo Fresia, De-lin DuanAbstract:Sampling locality, code, coordinates, sample size and RuBisCo spacer (rbc spacer) haplotype distribution in each Sargassum thunbergii population. (DOCX 15 kb
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Additional file 7: Table S6. of Historical isolation and contemporary gene flow drive population diversity of the brown alga Sargassum thunbergii along the coast of China
2017Co-Authors: Zhong-min Sun, Jian-ting Yao, Fu-li Liu, Pablo Fresia, De-lin DuanAbstract:Analysis of molecular variance (AMOVA) to partition genetic variance in the Northwest Pacific Sargassum thunbergii based on rbc spacer and SSR. (DOCX 14 kb
Liqin Wang - One of the best experts on this subject based on the ideXlab platform.
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a polysaccharide from Sargassum thunbergii inhibits angiogenesis via downregulating mmp 2 activity and vegf hif 1α signaling
International Journal of Biological Macromolecules, 2017Co-Authors: Xuezhi Sun, Jiancheng Liang, Fei Liu, Liqin WangAbstract:Abstract A water-soluble polysaccharide (STPC2) was isolated from the boiling-water extract of Sargassum thunbergii, purified by CaCl2 precipitation and chromatography on DEAE-cellulose and Sephacryl S-300 column. It was found that STPC2, with a molecular weight of 57 kD, was composed of fucose, xylose, galactose and glucuronic acid, in a ratio of 8.1: 3.8: 2.1: 1.0. Additionally, we found that STPC2 significantly inhibited endothelial cell migration and tube formation without toxicity. Moreover, STPC2 significantly inhibited lung cancer cell A549 migration and proliferation. It was found that STPC2 treatment suppressed MMP-2 gene expression at transcriptional level and enzymatic activity. Furthermore, STPC2 reduced the mRNA and protein expression of vascular endothelial growth factor-A (VEGF-A) and hypoxia-inducible factor (HIF)-1 alpha in the endothelial cells. Taken together, our findings indicated that STPC2 was a potent bioactive polysaccharide with distinct anti-angiogenesis activity against tumor migration via down-regulation of MMP-2 activity and VEGF/HIF-1α signaling pathway.
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A polysaccharide from Sargassum thunbergii inhibits angiogenesis via downregulating MMP-2 activity and VEGF/HIF-1α signaling
International journal of biological macromolecules, 2016Co-Authors: Xuezhi Sun, Jiancheng Liang, Fei Liu, Liqin WangAbstract:Abstract A water-soluble polysaccharide (STPC2) was isolated from the boiling-water extract of Sargassum thunbergii, purified by CaCl2 precipitation and chromatography on DEAE-cellulose and Sephacryl S-300 column. It was found that STPC2, with a molecular weight of 57 kD, was composed of fucose, xylose, galactose and glucuronic acid, in a ratio of 8.1: 3.8: 2.1: 1.0. Additionally, we found that STPC2 significantly inhibited endothelial cell migration and tube formation without toxicity. Moreover, STPC2 significantly inhibited lung cancer cell A549 migration and proliferation. It was found that STPC2 treatment suppressed MMP-2 gene expression at transcriptional level and enzymatic activity. Furthermore, STPC2 reduced the mRNA and protein expression of vascular endothelial growth factor-A (VEGF-A) and hypoxia-inducible factor (HIF)-1 alpha in the endothelial cells. Taken together, our findings indicated that STPC2 was a potent bioactive polysaccharide with distinct anti-angiogenesis activity against tumor migration via down-regulation of MMP-2 activity and VEGF/HIF-1α signaling pathway.
Li Feng - One of the best experts on this subject based on the ideXlab platform.
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Regeneration of germlings and seedlings development from cauline leaves of Sargassum thunbergii.
2010Co-Authors: Li Feng, Yuze MaoAbstract:A method of producing artificial Sargassum thunbergii seedlings is urgently desired to meet the increasing demand of raw materials used for aquaculture and for the sake of environmental protection. This is the first report of attempt to study the vegetative propagation of this species using cauline leaves under laboratory conditions. On average, 45.75% of the excised leaves survived and one leaf could produce several new individuals. Adventitious burgeons grew into branches about 2 mm in length after 3 months of culture. The new individuals were cutoff and could be used as seedlings for raft culture and seabed restoration after a further culture to elongate enough for hand-planting. Key words: Sargassum thunbergii, artificial seedling, brown seaweed, cauline leaves
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Studies on sexual reproduction and seedling-rearing of Sargassum thunbergii
Marine Fisheries Research, 2006Co-Authors: Li FengAbstract:The paper focus on characteristic and regularity of sexual reproduction of Sargassum thunbergii. It gives a systematical observation on S. thunbergii as follows: reproductive season, maturation of male and female receptacles, discharge of egg, discharge of sperm, zygote division, rhizoid formation, formation and growth of young sporophyte. In addition, zygote collection and seedling-rearing were carried out in laboratory, which had shown excellent results. The breeding technique is able to be applied in S.thunbergii seedling production.
Li Tao - One of the best experts on this subject based on the ideXlab platform.
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Effects of environment factors on young seedlings of Sargassum thunbergii by chlorophyll fluorescence method
Journal of Fisheries of China, 2011Co-Authors: Li TaoAbstract:Effects of different temperatures(5-34 ℃),different salinities(10-50),different nutrient concentrations and different nitrogen forms on chlorophyll fluorescence parameters of young seedlings of Sargassum thunbergii were researched in this paper.The main parameters determined in the study included the optimal chlorophyll fluorescence quantum yield(Fv/Fm)and the maximum relative electron transport rate(rETRmax)of photosystem II.The results are shown as follows:(1) If nitrogen concentration or phosphorus concentration was higher than 8 mg/L and 1.2 mg/L respectively,or temperature was greater than 28 ℃,there were significant effects on the photosynthesis of young seedlings of S.thunbergii.(2) Short time treatments in 5-15 ℃ and six hours treatments in 10-50 salinity of seawater did not affect the Fv/Fm of young seedlings of S.thunbergii obviously.(3) If nitrogen concentration and phosphorus concentration was 2-4 mg/L and 0.2-0.8 mg/L respectively,and moreover,NH+4-N∶NO-3-N was equal to 1-3,it was beneficial to the photosynthesis of young seedlings of S.thunbergii.
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Extraction of polysaccharides from Sargassum thunbergii by cellulase hydrolysis and ultrasound
2011Co-Authors: Li TaoAbstract:The extraction of polysaccharides from Sargassum thunbergii by cellulase hydrolysis and ultrasound was studied. Effects of four factors including ultrasonic power,cellulaseconcentration,extraction time and extraction temperature were discussed. On the basis of single factor analysis,the optimal operation variables were described through orthogonal experiment. Results indicated that influence of factors on the extraction were in the following order:extraction time,extraction temperature,ultrasonic power,and cellulase concentration. The optimal condition for extraction were:300 W ultrasonic power,3% cellulase,50 ℃ and 15 min. Moreover,the cellulase addition increased the extraction rate by 37.03% compared with the control group.
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Effects of light intensity, temperature and salinity on newborn branches of Sargassum thunbergii evaluated with chlorophyll fluorescence assay
Marine Sciences, 2011Co-Authors: Li TaoAbstract:The effects of different light intensity(25~220 μmol/(m2.s)),temperatures(5~34 ℃) and different salinities(0~60) on chlorophyll fluorescence parameters of newborn branches of Sargassum thunbergii were studies in this paper.The optimal chlorophyll fluorescence quantum yield of photosystem II(Fv/Fm),maximum relative electron transport rate(RrET,max) and initial slope of rapid light curve were determined.The results show:(1) The newborn branch of S.thunbergii suffered from high intensity light and high temperature stress easily and the Fv/Fmdecreased significantly under high intensity light.The photosynthesis was remarkably affected when the temperature was higher than 30℃.(2) One hour treatment at 5℃ or nine-hour treatment at 0~60 salinity affected the photosystem II obviously.However,the chlorophyll fluorescence parameters could nearly recover to normal level after 24 hours under standard culture condition except those in 60 salinity group.The preliminary analysis of the newborn branches of S.thunbergii about resistance physiology could provide reference for the artificial cultivation of S.thunbergii.
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Effect of Cu~(2+) on growth of Sargassum thunbergii young sporophyte
2010Co-Authors: Li TaoAbstract:The effect of Cu2+ on the growth of Sargassum thunbergii young sporophyte at different growth stage was investigated.It was found that during both the early and late stages the young sporophyte were very sensitive to Cu2+ treatment.Growth of S.thunbergii young sporophyte during the early stage was seriously inhibited by Cu2+ at concentrations of 5 μg/L and above,and the growth was almost terminated by Cu2+ at 250 μg/L and above.For S.thunbergii young sporophyte at the late stage,the growth was seriously inhibited by Cu2+ at 10 μg/L and above.The growth of young sporophytes was accelerated by 1 μg/L Cu2+,but slower or even ceased growth was observed at more than 50 μg/L Cu2+ treatments.Due to the special characteristics of structure and function,rhizoid of S.thunbergii young sporophyte was found to be insensitive to Cu2+.At the beginning of Cu2+ treatment,rhizoid still presented fast growth.