坛紫菜响应失水胁迫的代谢组学分析

为探究坛紫菜响应失水胁迫的机制,以坛紫菜(Pyropia haitanensis)为研究对象,采用超高效液相色谱-串联四级杆质谱(UPLC-MS/MS)技术分析了坛紫菜叶状体在失水/复水胁迫下的代谢组学变化。在坛紫菜提取物中检测和鉴定到了大量代谢物(已知的有206种)。利用Analyst 1.6.1软件对原始质谱数据进行采集,通过偏最小二乘判别分析法(PLS-DA)分析主成分,寻找差异代谢物。本研究发现坛紫菜失水组与正常对照组的代谢组间共有58种差异代谢物,失水条件下有38种上调,20种下调,主要包括一些氨基酸类及氨基酸衍生物、苯丙素类、甘油磷脂、核苷酸及其衍生物、黄酮类及类黄酮类、还有植物激素;富集到3条代谢通路,分别是氨酰-tRNA生物合成、嘌呤代谢以及半胱氨酸和蛋氨酸代谢通路。具有抗氧化能力的黄酮类物质、渗透保护因子脯氨酸和甜菜碱在叶状体失水时含量均升高,这表明它们在坛紫菜响应失水逆境中起重要的作用。坛紫菜失水组与复水组组间也存在较大代谢物差异,共筛选出50种差异代谢物,复水后有30种上调,20种下调,主要包括儿茶素及其衍生物、甘油磷脂、黄酮类、脂肪酸、萜类、氨基酸衍生物、苯丙素类以及植物激素类;富集到5条代谢通路,包括:半胱氨酸/蛋氨酸代谢、甘氨酸/丝氨酸/苏氨酸的代谢、D-丙氨酸代谢、氨酰-tRNA生物合成和ABC转运通路。坛紫菜复水组与对照组的组间有42种差异代谢物。与对照组相比,复水组有31种代谢物上调和11种下调,主要包括氨基酸类及氨基酸衍生物、儿茶素衍生物、黄酮类、苯丙素类、萜类和脂肪酸等,仅富集到半胱氨酸和蛋氨酸代谢这一条代谢通路。多种代谢物的变化说明坛紫菜中有多种响应胁迫的策略来使其适应生存环境。

Insights into community-based bioassessment of environmental quality status using microphytobenthos in estuarine intertidal ecosystems

The feasibility of community-based bioassessment of environmental quality status was studied using microphytobenthos（MPB） in estuarine intertidal ecosystems.The sediment samples of MPB were collected monthly during a 1-year cycle（September 2006-August 2007） at four sampling stations in the Nakdong River Estuary,Korea.Environmental variables,such as salinity,radiation,grain size of sediment,Si（OH）4（Si）,nitrate（NO3^-）,nitrite（NO2^-）,ammonium（NH4~＋） and phosphates（PO4^（3-））,were measured synchronously for comparison with biotic parameters.The statistical analyses were carried out for assessment the relationship between biotic and environmental parameters.The results showed that：（1） the MPB community structures were significant differences among four sampling stations;（2） spatial variation in the MPB communities were significantly correlated with environmental variables,especially the nutrient NH4＋ in combination with salinity and grain size;（3） three species（Navicula lacustris,Pleurosigma anglulatum and Fragilaria sp.1） were significantly correlated with nutrients and/or Si;and（4） the species richness and diversity were significantly correlated with the grain size.It is suggested that MPB communities may be used as a potentially robust bioindicator for assessing environmental quality status in estuarine intertidal ecosystems.

DNA Barcoding Assessment of Green Macroalgae in Coastal Zone Around Qingdao, China

An assessment with assistance of DNA barcoding was conducted on green macroalgae in coastal zone around Qingdao, China, during the period of April- December, 2011. Three markers were applied in molecular discrimination, including the plastid elongation factor tufA gene, the internal transcribed spacer(ITS) region of the ribosomal cistron and rubisco large subunit gene 3' regions(rbcL-3P). DNA barcoding discriminated 8 species, excluding species of genus Cladophora and Bryopsis due to failures in amplification. We ascertained and corrected 4 species identified by morphological methods for effectively assisting the classification. The gene tufA presented more advantages as an appropriate DNA marker with the strongest amplification success rate and species discrimination power than the other two genes. The poorest sequencing success largely handicapped the application of ITS. Samples identified by tufA and rbcL as Ulva flexuosa were clustered into the clade of U. prolifera by ITS in the neighbor-joining tree. Confusion with discrimination of the complex of U. linza, U. procera and U. prolifera(as the LPP complex) still existed for the three DNA markers. Based on our results, rbcL is recommended as a preferred marker for assisting tufA to discriminate green macroalgae. In distinguishing green-tide-forming Ulva species, the free-floating sample collected from the green tide in 2011 was proved to be identical with U. prolifera in Yellow Sea for ITS and rbcL genes. This study presents a preliminary survey of green macroalgae distributed in the coastal area around Qingdao, and proves that DNA barcoding is a powerful tool for taxonomy of green macroalgae.

Trace Metals Analysis Along the Fildes Peninsula Coastline Using Two Red Algae, Rhodymenia antarctica and Iridaea cordata, as Monitors

Two red algae, Rhodymenia antarctica and Iridaea cordata(Rhodophyta), were employed to investigate the pollution situation along Fildes Peninsula coastline, King George Island. Ten sites from east and west coastlines were investigated, and the concentrations of Cu, Pb, Zn, Cd, Cr, As and Hg were determined. The metal pollution index(MPI) was used to evaluate the overall pollution level represented by the investigated sites and for interregional comparisons. The two algae exhibited different preference to special trace metal. R. antarctica could accumulate more Cd(0.63 mg kg^(-1)) and Hg(0.026 mg kg^(-1)) than I. cordata(Cd 0.34 mgkg^(-1), Hg 0.019 mg kg^(-1)). I. cordata could accumulate more As(15.53 mg kg^(-1)) than R. antarctica(10.11 mg kg^(-1)). There was no significant difference in accumulating Cu, Pb, Zn and Cr between the two algae. R. antarctica could be used to monitor Cd and Hg. I. cordata would be more appropriate for monitoring As. MPI monitored by the two algae were from 1.02 to 2.26(R. antarctica), and 1.03 to 1.25(I. cordata), respectively. Pollution situation of Fildes Peninsula was becoming serious, especially of the east coastline. The objective of this research was to gather the baseline information for trace metals investigation in Antarctic.

Estimating areal carbon fixation of intertidal macroalgal community based on composition dynamics and laboratory measurements

The community dynamics and potential carbon ?xation of intertidal macroalgae were investigated monthly from April 2014 to April 2015 in the northwest coast of Yellow Sea. Seasonal variations in biomass and carbon ?xation were presented and showed close relationship with community structure.The carbon ?xation rate ranged from 0.48±0.13 mg C/(g FW ·d) to 4.35±0.12 mg C/(g FW ·d). Sargassum thunbergii, Chondrus ocellatus and Ulva intestinalis were three most in?uential species which contributed27%, 21.9% and 18.5% variation of carbon ?xation rate, respectively. Standing carbon stocks ranged from7.52 g C/m^2 to 41.31 g C/m^2, and estimated carbon stocks varied from 11.77 g C/m 2 to 96.49 g C/m^2. The larger dif ference between estimated and standing carbon stocks implied that more ?xed carbon was exported from the community in summer and autumn than in winter. This study suggested that intertidal macroalgal community could provide a potential function in carbon ?xation of coastal ecosystem.

Behavioral and physiological photoresponses to light intensity by intertidal microphytobenthos

Abstract Behavioral and physiological responses to light are the two major mechanisms by which natural microphytobenthic assemblages adapt to the intertidal environment and protect themselves from light stress. The present study investigated these photoresponses with different light intensities over 8 h of illumination, and used a specific inhibitor （Latrunculin A, Lat A） for migration to compare migratory and non-migratory microphytobenthos （MPB）. Photosynthetic activity was detected using rapid light curves and induction curves by chlorophyll fluorescence. It showed distinct variation in migratory responses to different light intensities; high light induced downward migration to avoid photoinhibition, and low and medium light （50-250 ~tmol/（m2. s）） promoted upward migration followed by downward migration after certain period of light exposure. No significant difference in non-photochemical quenching （NPQ） or PSII maximal quantum yidd （Fv/Fm） was detected between low and medium light irradiance, possibly indicating that only high light influences the photosynthetic capability of MPB. Decreased photosynthetic activity, indicated by three parameters, the maximum relative electron transport rate （rETRmax）, minimum saturating irradiance （E0 and light utilization coefficient （a）, was observed in MPB after exposure to prolonged illumination under low and medium light. Lat A effectively inhibited the migration of MPB in all light treatments and induced lower Fv/Fm under high light （500 and 100 μmol/（m2·s）） and prolonged illumination at 250 μmol/（m2·s）, but did not significantly influence Fv/Fm under low light （0-100 μmol/（m2·s）） or NPQ. The increase of NPQ in Lat A treatments with time implied that the MPB assemblages can recover their physiological photoprotection capacity to adapt to light stress. Non-migratory MPB exhibited lower light use efficiency （lower a） and lower maximum photosynthetic capacity （lower rETRm^x） than migratory MPB under light intensities above 250μmol/（m2. s） after 4.0 h illumination.

紫菜腐霉激发子基因家族特征及其在感染过程中的作用

【背景】激发子(elicitin)是卵菌(Oomycetes)疫霉和腐霉分泌的可诱发宿主产生免疫反应的小分子化合物。【目的】鉴定紫菜腐霉激发子基因家族,分析其结构特征和在感染宿主过程中可能的作用机制。【方法】运用同源比对法筛查紫菜腐霉NBRC33253基因组中激发子基因家族成员,利用生物信息学工具分析激发子家族的理化性质和系统进化,并结合转录组数据和GO功能注释,探讨其在感染宿主过程中可能的作用机制。【结果】紫菜腐霉基因组中发现22个激发子基因家族成员,其中,17个为胞外分泌蛋白,4个定位于质膜,1个锚定于高尔基体。紫菜腐霉激发子基因结构简单保守,含有1-2个CDS序列,每个成员基因编码的氨基酸数目介于114-2100 aa之间,等电点PI在3.61-9.88之间;系统进化分析显示,紫菜腐霉激发子家族成员存在扩张;表达模式分析说明,紫菜腐霉激发子在感染宿主后6个激发子基因表达量上调,7个激发子基因表达量下调,推测可能具有多个生物学功能,如GO功能注释到纤维素结合激发子凝集素(cellulosebinding elicitor lectin,CBEL)和共生体对宿主防御相关程序性细胞死亡的调节过程。【结论】紫菜腐霉激发子基因家族结构保守,均属于ELL(elicitin-like)亚类,可能具有纤维素结合激发子凝集素(CBEL)和加速宿主细胞程序性死亡的功能,结合纤维素,附着在宿主表面,发挥蛋白激酶活性,触发宿主MAPK信号传导通路介导的免疫反应,促进HR细胞死亡。本研究为进一步解析紫菜腐霉的致病机制及紫菜抗病性状的遗传育种提供了理论基础。