日本大叶藻(Zostera japonica)根状茎和不同发育阶段叶片的热值动态

对广西沿岸海草优势种日本大叶藻(Zostera japonica)根状茎、幼叶、成熟叶和老叶的灰分含量、干质量热值和去灰分热值进行了初步研究。结果表明,(1)日本大叶藻叶片从幼叶到成熟叶再到老叶的生长发育过程中,灰分含量升高,而干质量热值和去灰分热值下降;(2)日本大叶藻根状茎的灰分含量和去灰分热值大于叶片的灰分含量和去灰分热值,而干质量热值无明显的差别;(3)日本大叶藻的灰分含量、干质量热值和去灰分热值低于红树植物的相应指标。

大叶藻(Zostera marina L.)PSⅠ和PSⅡ复合物的分离鉴定

采用蔗糖密度梯度离心法分离纯化大叶藻类囊体膜 ,经 1 0 %SDS增溶后 ,用蔗糖密度梯度超速离心分离其色素蛋白质复合物。经稳态光谱分析、DCIP光还原活性测定及P680 、P70 0 差示光谱检测结果表明 ,2 0 %蔗糖层的CP3和 40 %蔗糖层 (上 )的CP4为PSⅡ复合物 ,具有光化学活性 ;40 %蔗糖层 (下 )的CP5为PSⅠ复合物 ,其P70 0 特征吸收峰位于 695nm处。CP3和CP4的DCIP光还原活性 :CP3为 34.2 7微电子当量 /(mgchl·h) ,CP4为 7.2 9微电子当量 /(mgchl·h)。

大叶藻(Zostera marina)的热值和元素含量(碳、氮、磷)及其相关性

选取辽宁獐子岛近岸海域大叶藻样品,对其须根、根状茎和不同生长阶段叶片的灰分含量、热值和元素含量(碳、氮、磷)及其相关性进行研究,结果表明:在不同生长阶段,叶片长度随着生长顺序先增大后减小;灰分含量随着叶片生长逐渐升高,且极显著小于根状茎和须根(P<0.01);不同部位干质量热值差异极显著(P<0.01),以初生叶最高,为(14.89±0.040)k J/g,后逐渐减小,在须根中最小,为(8.15±0.079)k J/g;不同生长阶段叶片的去灰分热值差异不大,但极显著大于须根和根状茎(P<0.01);碳、氮、磷含量均呈同一趋势:初生叶>幼叶>成熟叶1>成熟叶2>衰老叶>根状茎>须根;N/P比值为27.08,说明大叶藻存在P限制;N/P比值在根状茎中最大,须根中最小,这说明大叶藻存在能量的转移和存贮;大叶藻不同部位灰分含量与干质量热值、去灰分热值、碳含量、氮含量、磷含量之间呈极显著的负相关(P<0.01),干质量热值与碳含量、氮含量、磷含量之间呈极显著的正相关(P<0.01);大叶藻不同部位的热值与碳、氮、磷元素含量之间均呈显著的线性关系(P<0.05)。

Generation and analysis of expressed sequence tags from the salt-tolerant eelgrass species, Zostera marina

Zostera marina, a monocotyledonous angiosperm, is one of the most important seagrass species. To inves- tigate the salt-tolerance mechanism and discover salt-tolerant genes in Z. marina, a cDNA library was con- structed. Single-pass sequencing of the 5＇ ends of 4 081 clones yielded 4 002 high quality expressed sequence tags （ESTs）, which were assembled into 241 contigs and 1 673 singletons, representing 1 914 unigenes. The average length of the ESTs was 582 bp, with sizes ranging from 100-1 500 bp. Basic Local Alignment Search Tool （BLASTX） analysis revealed that 1 664 unigenes had significant homology to known genes in the Na- tional Center for Biotechnology Information （NCBI） non-redundant （nr） database （E-value≤5-10）. Among them, the two most abundant genes encoded metallothionein （157 ESTs） and chlorophyll a/b-binding pro- tein （38 ESTs）, accounting for 7.1% and 1.7% of the total ESTs, respectively. Using Kyoto Encyclopedia of Genes and Genomes （KEGG）, 1 462 unigenes were assigned to 1 161 pathways （E-value≤5-10）. A total of 938 unigenes were assigned Gene Ontology （GO） terms based on the GO hierarchy analysis, and InterProScan searches recognized 1 003 InterPro families. Three genes for metallothionein in Z. marina that belonged to Class II was identified. Results of this study will improve understanding of the molecular mechanisms of saline tolerance in Z. marina.

Biotic and Abiotic Conditions Can Change the Reproductive Allocation of Zostera marina Inhabiting the Coastal Areas of North China

The relationships between reproductive allocation and different factors have been widely recognized for terrestrial plants, but scarcely for marine angiosperms. Focusing on the seagrass Zostera marina, we examined the change in biomass when it was partitioned to growth, vegetative propagation and reproductive allocation of Z. marina. We also evaluated the relationships between reproductive allocation and biotic and abiotic conditions in the coastal areas of north China. The results indicated that the reproductive allocation of Z. marina at the levels of genet, shoot and spathe was positively correlated with shoot characteristics such as height and biomass(P < 0.01), but was negatively correlated with branch number and leaf number per genet(P < 0.01). In addition, the allocation was also affected by other abiotic factors such as water column phosphate concentration(P < 0.05) and sediment total petroleum(P < 0.01). These findings indicated that both biotic and abiotic conditions significantly influenced the reproductive allocation of Z. marina, which may affect further the population dynamics.

Cloning, characterization and expression analysis of a microsomal glutathione S-transferase gene from the seagrass Zostera marina

The response of glutathione S-transferase(GST)in Zostera marina to temperature variation was analyzed at molecular level by cloning the microsomal GST gene and texting the microsomal GST expression regularity under different temperature.Specific speaking,express ZmGST in Escherichia coli,then purify the recombinant protein and make the thermal stability analysis.Therefore,the experiments were carried out to provide a theoretical basis for the further elaboration to the population degradation mechanisms of Z.marina.In conclusion,the thermostability and the response of ZmGST gene to temperature changes can determine its temperature tolerance range,and affect its resilience in turn.

Influences of diel and tidal cycles on fish assemblage in eelgrass(Zostera marina) bed of southern Korea during autumn

Short-term tidal and diel variations of autumn fish assemblage in a Zostera marina bed were investigated using 3 h interval samplings for 24 h in both spring and neap tide using a small beam trawl.A total of 1 346 fishes belonging to 19 species were collected at spring tide,whereas 1 115 fishes belonging to 17 species were at neap tide.The common fish species were Nuchequula nuchalis,Acanthogobius flavimanus,Takifugu niphobles,Acentrogobius pflaumii,and Pholis nebulosa with the former three species dominating at spring tide,while the latter two species being abundant at neap tide.Diel variation in abundance was significant with higher abundance at night than day,but there were no significant differences between spring and neap tides,and between ebb and flood tides（three-way ANOVAs）.Diel variation in the abundance of fishes may be influenced by tidal range and cycle,and day-night differences of food availability and behaviors of fishes indirectly.Non-metric multidimensional scaling（n MDS） ordination and analysis of similarity（ANOSIM） results revealed significant differences in species compositions both between day and night,and between spring and neap tide.Eelgrass beds are highly productive marine ecosystem,and thus,our results will contribute to conservation of seagrass ecosystem in the study area.

荣成天鹅湖大叶藻(Zostera marina)间2 种小型腹足类的分类学研究

小型腹足类生物在我国种类繁多,但其相关研究在国内基本属于空白。本文对荣成天鹅湖大叶藻间的2种小型腹足类生物进行了形态学及分子生物学(16S和28SrRNA基因片段)研究。结果表明,根据形态学所鉴定的短剑螺属未定种Machae roplax sp.,应为畦螺属未定种Lirularia sp.;分子生物学研究结果支持形态学对刺绣翼螺Alabapicta的鉴定。同时,与A.picta有一定形态学差异的其它4种相近形态的小型腹足类,在基因序列及遗传距离上与刺绣翼螺非常接近,亦应为刺绣翼螺Alaba picta。

Distinct root system acclimation patterns of seagrass Zostera japonica in sediments of different trophic status:a research by X-ray computed tomography

Conspecific seagrass living in differing environments may develop different root system acclimation patterns.We applied X-ray computed tomography(CT)for imaging and quantifying roots systems of Zostera japonica collected from typical oligotrophic and eutrophic sediments in two coastal sites of northern China,and determined sediment physicochemical properties that might influence root system morphology,density,and distribution.The trophic status of sediments had little influence on the Z.japonica root length,and diameters of root and rhizome.However,Z.japonica in oligotrophic sediment developed the root system with longer rhizome node,deeper rhizome distribution,and larger allocation to below-ground tissues in order to acquire more nutrients and relieve the N deficiency.And the lower root and rhizome densities of Z.japonica in eutrophic sediment were mainly caused by fewer shoots and shorter longevity,which was resulted from the more serious sulfide inhibition.Our results systematically revealed the effect of sediment trophic status on the phenotypic plasticity,quantity,and distribution of Z.japonica root system,and demonstrated the feasibly of X-ray CT in seagrass root system research.

A genome-wide analysis of the chloroplast NADH dehydrogenase - like genes in Zostera marina

The chloroplast NADH dehydrogenase-like(NDH)complex,homologous to respiratory complex I,participates in photosystem I cyclic electron flow(PSI-CEF)and chlororespiration in photosynthesis.Phylogenetic analyses indicated that Zostera marina,a widely distributed seagrass,has a complete NDH complex,which is rarely observed in marine macrophytes.We identified all 31 ndh genes necessary for the functional NDH complex,of which ndhB and pnsb3 occurred as duplication events.Secondary structural analyses of antiporter-like subunits showed that the long amphipathic helix of NdhF was lost in Z.marina,which could exhibit an alternative mode in the generation of trans-thylakoid proton gradient.The splicing pattern of ndh exhibited tissue-specific patterns and responded to light stress.RNA editing in Z.marina presented the ancestral pattern with many of the primitive editing sites and types.The partial editing in ndhF reflected the link between light stress and RNA editing.Moreover,the predominant expression in leaves of most ndh genes suggested that their major function is in photosynthesis.The quantitative real time-PCR results show that the expression of ndh was signifi cantly upregulated in response to light stress.Nevertheless,there were two diverse responsive mechanisms of the NDH complex in PSI-CEF and chlororespiration.Overall,the presence of a complete structure,upregulated gene expression level,and multiple post-transcriptional regulations could provide a molecular basis for the powerful NDH complex and enable Z.marina to maintain eff ective photosynthetic performance.

Isolation and Identification of Flavonoids Found in Zostera marina Collected in Norwegian Coastal Waters

In extracts of the seagrass Zostera marina, collected in coastal waters of West-Norway, fourteen different flavones and high amounts of rosmarinic acid were identified. Five of the flavones were found to be sulphated, among these were luteolin 7,3'-disulphate and chrysoeriol 7-sulphate structures previously not published with complete NMR assignments. Luteolin 7-O-β-(6''-malonyl) glucoside, and two other malonylated flavone compounds occurring in trace amounts, were identified for the first time in Z. marina. The sulphated flavones were fairly stable in slightly acidified (0.1% trifluoroacetic acid) extracts stored for months, however, under more acidic conditions (0.5% trifluoroacetic acid in the extracts) they were susceptible to undergo hydrolyses. When the solvents of purified fractions were removed by rotary evaporation, the sulphated flavones quickly decomposed to their corresponding aglycones due to the increased acid concentrations.

Artificial seed germination and seedling production of Zostera marina L.by salinity manipulation

Vast declines in Zostera marina seagrass beds demand effective methods of rehabilitation. In this study, we developed a practical method by reducing salinity to induce seed germination followed with recovering salinity to facilitate seedling production of Z. marina. The results showed that Z. marina seeds collected from natural seawater（salinity 30） were induced to germinate at reduced salinities. Percent germination（GR） was higher and mean-time-to-germinate（MTG） was shorter at lower salinities. The highest GR and shortest MTG occurred at salinity 0（deionized freshwater）. After germination in freshwater, seeds could develop into seedlings at salinities5–30 and continue the growth. Viability or development of germinated seeds was not significantly different during the 40 d of post-germination incubation at salinities 5–15 after 1–20 d of germination in freshwater. However,during the process of translating germinated seeds from salinity 0 and 5 to salinity 30, reducing the gradients of post-germination acclimation facilitated more seeds forming seedlings in less time. On average, after 60 d of static incubation, including 20 d in freshwater for germination followed with immediate shift to salinity 5 and increasing to salinity 30 at increment of 5 every two days until cultivation at constant salinity 30, 33% of Z. marina seeds produced healthy seedlings. The results indicate that the salinity-manipulation based method of artificial germination and seedling production is practical and effective in supporting rehabilitation of Z. marina bed.

Recent Trends of Zostera marina (Eelgrass) in a Highly Eutrophic Coastal Lagoon in the Mid-Atlantic Region (USA)

Spatial and temporal characteristics of Zostera marina (eelgrass) in the Barnegat Bay-Little Egg Harbor Estuary are compared before (2004-2011) and after (2012-2013) major fertilizer legislation (Fertilizer Law A2290) was enacted in New Jersey (USA) to reduce nutrient inputs from fertilizers to water bodies in the state. A significant decrease of Z. marina biomass and areal cover occurred in this eutrophic estuary between 2004 and 2011 concomitantly with increasing nitrogen and phosphorus loading from the watershed. The rate of decline in aboveground and belowground biomass was significantly sharper during 2004-2006 than during 2008-2010. In 2010, Z. marina biomass dropped to a very low level (mean aboveground biomass = 7.7 g dry wt mDŽ;mean belowground biomass = 27.0 g dry wt mDŽ), persisting through the last sampling period (October-November) in 2013. Biomass and areal cover of Z. marina decreased even further after Fertilizer Law A2290 was enacted in January 2012, with the lowest values recorded from August to November each year. These low values are the result of ongoing eutrophication of the system. More seagrass monitoring and research are necessary in future years to determine if the fertilizer law will have a positive effect on Z. marina condition in the estuary over the long term.

黄河口日本鳗草(Zostera japonica)在环境胁迫下的光合响应研究

针对黄河口日本鳗草面临的水体浊度变化造成的光限制及重金属污染等双重胁迫,综合野外监测和室内控制实验,分别研究了水体浊度、重金属Cu胁迫以及重金属Cu与浊度耦合胁迫下的日本鳗草光合响应特征.研究发现:浊度胁迫、浊度与低浓度重金属Cu耦合胁迫下,日本鳗草叶片叶绿素含量降低,光合色素的合成受到抑制;叶绿素a与叶绿素b的质量比值较高,表明捕光色素复合体II含量低的同时,叶片通过减少对光能的捕获,降低了日本鳗草光合机构遭受破坏的风险;而在单一的浊度胁迫下,随着光化学猝灭系数下降,日本鳗草用于电子传递的能量逐渐减少,光能利用效率降低;随胁迫时间延长,日本鳗草最大光化学效率也出现下降;同样单一重金属Cu胁迫下,日本鳗草对Cu长期处理表现出抗性差,其光合作用也受到较大影响.据此推测,日本鳗草是对浊度胁迫有一定适应性的海草种类,但污染胁迫如重金属Cu对日本鳗草光合作用影响比水体浊度胁迫影响更大.

大叶藻(zostera marina L.)生态学研究进展

海草床是海洋生态系统重要的组成部分,具有很高的初级生产力,近年来由于人类活动的影响,海草床退化严重,1993—2003期间,全球有约15%的海草生态区消失,面积达到了26000 km2,大叶藻是其中的典型代表。本文总结了大叶藻生态学的研究进展,包括大叶藻的恢复及生产力研究,并总结了国内大叶藻生态学研究存在的问题。

黄河口互花米草对日本鳗草Zostera japonica的入侵生态效应

日本鳗草(Zostera japonica)是中国沿海潮间带较为常见的海草种类,随着全球变化和人类活动干扰的影响,面临着生境破碎化、种群退化的巨大威胁。互花米草(Spartina alterniflora)入侵是当前中国滨海生态系统中突出的生态问题之一,对黄河口日本鳗草种群带来巨大影响。通过野外控制实验发现,不同密度互花米草对其共生的日本鳗草植株个体和种群有明显的抑制作用,茎枝密度、茎枝高度和总生物分别下降了92.6%~99.9%、56.6%~78.7%、98%~100%。通过分类遥感影像得出,日本鳗草生境格局经历了2009年至2013年的扩张期至6.42 km^2,以及2013年至2017年的萎缩期,鳗草的生境面积下降为3.98 km^2。黄河口互花米草入侵日本鳗草生境规模由2009-2013年的0.32 km^2扩大到2013-2017年的1.77 km^2,占到日本鳗草生境总面积的27.55%。互花米草入侵对本地物种的生境侵占是导致日本鳗草种群退化的重要原因,因此对互花米草入侵的控制、防御以及日本鳗草的监测、保护与修复将是当前和未来中国滨海湿地海草床保护领域的重大研究议题。

Influence of Temperature and Salinity on Germination of Eelgrass (Zostera marina L.) Seeds

Seagrass restoration as part of ocean ecosystem protection has been launched for many years all over the world, but intensive research on this subject in China has just begun in recent years. Seed broadcasting has been widely accepted as the most potentially useful method for seagrass restoration over large areas. We examined the influence of key environmental factors on seed germination to help promote eelgrass bed restoration. Under anoxic conditions, the influence of temperature and salinity on the germination rate of eelgrass (Zostera marina L.) seeds was examined at different combinations of four temperatures (4, 9, 14, and 24℃) and nine salinities (5 to 45, increment of 5). The effect of significant interaction of temperature and salinity on germination rate was observed (ANOVA) (P<0.001). The highest germination rate (83.3 ± 3.5)% was reached in 8 weeks at 14℃ and salinity 5. Higher temperature significantly increased the germination rate at salinity 5 (P<0.001) during the whole observation period except for 24℃, while lower salinity significantly increased the germination rate at 14℃ (P<0.001). Although significant interaction was found between temperature and salinity (P<0.001), the influence of salinity was stronger than that of temperature for the germination of eelgrass seeds. These results provide useful information for the propagation of artificial seedlings for seagrass restoration in China.

Habitat suitability analysis of eelgrass Zostera marina L. in the subtidal zone of Xiaoheishan Island

We present a GIS-based habitat suitability index(HSI) model to identify suitable areas for Zostera marina L. restoration in the subtidal zone of Xiaoheishan Island. The controlling factors in the model,in order of importance,are Secchi depth,sediment composition,water temperature,salinity,current velocity,water depth and nutrient quality. Specific factor piecewise functions have been used to transform parameter values into normalized quality indexes. The weight of each factor was defined using expert knowledge and the analytic hierarchy process(AHP) method. All of the data thus obtained were interpolated using the inverse distance weighted(IDW) interpolation method to create maps for the entire region. In this study,the analysis of habitat suitability in the subtidal zone of Xiaoheishan Island was conducted for four seasons. According to the GIS-based HSI model,the optimal habitat of Z ostera marina L. appears in spring,although habitat remains suitable all year round. On the whole,the optimum site for eelgrass restoration is located in the eastern region,followed by the western and southern regions. We believe that the GIS-based HSI model could be a promising tool to select sites for Z ostera marina L. restoration and could also be applicable in other types of habitat evaluation.

Antibacterial Activity of Extracts from Zostera marina Against Pathogens of Apostichopus japonicus Skin Ulceration Disease

The purpose of this study was to investigate the antibacterial activity of extracts from Zostera marina against the pathogens of Apostichopus japonicus skin ulceration disease.When 95% ethanol (v/v) solvent was used to extract Zostera marina at 50℃,aqueous extract (ZA) showed obvious bacteriostatic effects on the tested bacterial strains (inhibition halo diameters between 8.23 mm and 13.62 mm),whereas the ethyl acetate extract (ZE) was almost inactive.The minimal inhibitory concentration (MIC) of ZA against four pathogens were homogeneous at 12.8 g L-1.ZA components were analyzed by thin layer chromatography (TLC) assay and six fractions were obtained.In another study,the six fractions showed inhibitory effects against the tested bacteria while their functions seemed to counteract the ZA activity.

Identification of Light-Harvesting Chlorophyll a/b-Binding Protein Genes of Zostera marina L.and Their Expression Under Different Environmental Conditions

Photosynthesis includes the collection of light and the transfer of solar energy using light-harvesting chlorophyll a/b-binding(LHC) proteins.In high plants,the LHC gene family includes LHCA and LHCB sub-families,which encode proteins constituting the light-harvesting complex of photosystems I and II.Zostera marina L.is a monocotyledonous angiosperm and inhabits submerged marine environments rather than land environments.We characterized the Lhca and Lhcb gene families of Z.marina from the expressed sequence tags(EST) database.In total,13 unigenes were annotated as Zm Lhc,6 in Lhca family and 7 in Zm Lhcb family.Zm LHCA and Zm LHCB contained the conservative LHC motifs and amino acid residues binding chlorophyll.The average similarity among mature Zm LHCA and Zm LHCB was 48.91% and 48.66%,respectively,which indicated a high degree of divergence within Zm LHChc gene family.The reconstructed phylogenetic tree showed that the tree topology and phylogenetic relationship were similar to those reported in other high plants,suggesting that the Lhc genes were highly conservative and the classification of Zm Lhc genes was consistent with the evolutionary position of Z.marina.Real-time reverse transcription(RT) PCR analysis showed that different members of Zm Lhca and Zm Lhcb responded to a stress in different expression patterns.Salinity,temperature,light intensity and light quality may affect the expression of most Zm Lhca and Zm Lhcb genes.Inorganic carbon concentration and acidity had no obvious effect on Zm Lhca and Zm Lhcb gene expression,except for Zm Lhca6.