Photoperiod Mediates the Effects of Temperature and Light Intensity on the Proliferation of Ulva prolifera

In order to study the complex effects of photoperiod,temperature,and light intensity on the spore maturation and release number of Ulva prolifera,we cultured thalli segment(2–3 mm)under three different photoperiods(L:D=12:12,14:10 and 10:14),temperature(15℃(LT),25℃(MT)and 30℃(HT))and light intensity(100,200 and 400μmol m^(−2)s^(−1),noted as LL,ML and HL,respectively)conditions.Then the maturation time,spore release number and chlorophyll fluorescence were analyzed.The results suggested that:1)The spore maturation time was accelerated by higher temperature or higher light intensity from 62 h to 36 h,and changes in day length accelerated the spore maturation to a certain extent as compared with 12:12 light/dark cycle;2)Higher light intensity significantly decreased the chlorophyll fluorescence(Fv′/Fm′,NPQ,rETRmax andα)of the mature reproductive segment under 30℃with 12:12 light/dark cycle.But when in the other photoperiods(10:14 and 14:10 conditions),the inhibitory effects of high light intensity were alleviated significantly;3)The optimum condition for the spore maturation and release was 12:12 light/dark cycle,25℃,400μmol m^(−2)s^(−1),with both shorter and longer photoperiod reducing the spore release number;4)Higher light intensity significantly increased the spore release number under 25℃,but these effects were alleviated by 30℃treatment.This study is the first attempt to elucidate the coincidence effects of photoperiod,temperature and light intensity on the reproduction of Ulva,which would help to reveal the mechanism of the rapid proliferation of green tide.

Genome-wide SNP markers provided insights into the reproductive strategy and genetic diversity of the green tide causative species Ulva prolifera in China

Ulva prolifera is the causative species of the annually occurring large-scale green tides in China since 2007.Its specific biological features on reproductivity strategies,as well as intra-species genetic diversity,are still largely unknown,especially at the genome level,despite their importance in understanding the formation and outbreak of massive green tides.In the present study,the restriction site-associated DNA genotyping approach(2b-RAD)was adopted to identify the genome-wide single-nucleotide polymorphisms(SNPs)of 54 individual thalli including samples collected from Subei Shoal in 2019 and Qingdao coast from 2019 to 2021.SNPs genotype results revealed that most of the thalli in 2019 and 2020 were haploid gametophytes,while only half of the thalli were gametophytes in 2021,indicating flexibility in the reproductive strategies for the formation of the green tides among different years and the dominance of asexual and vegetative reproductive mode for the floating period.Besides,population analysis was conducted,and it revealed a very low genetic diversity among samples from Subei Shoal and the Qingdao coast in the same year and a higher divergence among samples in different years.The results showed the efficiency of 2b-RAD in the exploration of SNPs in U.prolifera and provided the first genome-wide scale evidence for the origin of the large-scale green tides on the Qingdao coast.This study improved our understanding of the reproductive strategy and genetic diversity of the green tide causative species and will help further reveal the biological causes of the green tide in China.

盐度对浒苔(Ulva prolifera)微观繁殖体萌发生长及藻体繁殖的影响

黄海绿潮起源于苏北浅滩,每年夏天漂移到青岛沿岸泛滥成灾,对生态环境造成严重破坏。苏北浅滩受沿岸径流输入影响,盐度变化范围大,青岛海域盐度较稳定,稍高于苏北浅滩。盐度对浒苔微观繁殖体萌发、藻体生长及繁殖过程具有重要作用,通过室内连续受控实验,系统研究了固定盐度(5、10、15、20、25、30、33、35)和变化盐度(盐度逐渐降低)对浒苔微观繁殖体固着、萌发、藻体生长和繁殖不同阶段的影响,主要结论如下:固着阶段,盐度5不利于浒苔微观繁殖体的固着,盐度10~35对微观繁殖体固着的影响不显著,相同盐度下,孢子的固着量显著高于配子。萌发阶段,不同盐度(5~35)及不同盐度变化形式对微观繁殖体(孢子和配子)的萌发没有显著影响,孢子的萌发速度快于配子,最终均能完全萌发。生长阶段,低盐(5~15)不利于浒苔幼苗的生长。繁殖阶段,当盐度≤10时,浒苔不进行生殖活动;盐度15~35范围内,浒苔可以产生微观繁殖体,完成一个完整的生活史;在绿潮形成过程中,孢子的生殖策略为K对策,配子的生殖策略为R对策。上述结论表明,在苏北浅滩和青岛海域,盐度不是限制浒苔发生发展及繁殖过程的关键环境因子,明确了盐度在绿潮发生过程的作用,为揭示绿潮暴发机制提供科学依据。

A multi-module with a two-way feedback method for Ulva drift-diffusion

The outbreak of Ulva in the Yellow Sea has seriously affected marine ecology and economic activities.Therefore,effective prediction of the distribution of Ulva is of great significance for disaster prevention and reduction.However,the prediction method of Ulva is mainly based on numerical simulation.There are two problems with these methods.First is that the initial distribution of Ulva is simulated using independent pixel-level particles.Besides,the influence of Ulva growth and diffusion on the drift is not considered.Therefore,this paper proposes a multi-module with a two-way feedback method(MTF)to solve the above problems.The main contributions of our approach are summarized as follows.First,the initialization module,the generation and elimination module,and the drive module are composed in our way.Second,we proposed an initialization method using rectangle objects to simulate the Ulva distribution extracted from remote sensing images.Thirdly,the drift and diffusion mechanism of the Ulva is considered to realize the two-way feedback between the generation and elimination module and the drive module.The results of our experiments show that the MTF performs better than the traditional method in predicting the drift and diffusion of Ulva.The code is already publicly available at https://github.com/UPCGIT/A-multi-module-with-a-two-way-feedback-method-for-Ulva-drift-diffusion.

Characterization of SARS-COV-2 main protease inhibitory peptides from Ulva prolifera proteins

The main protease(M^(pro))is essential for the replication of SARS-COV-2 and therefore represents a promising anti-viral target.In this study,we screened M^(pro)inhibitory peptides from Ulva prolifera protein on in-silico proteolysis.Cytotoxicity analysis using the online toxic prediction tool ToxinPred revealed that all the peptides were non-cytotoxic.The hexapeptide(SSGFID)exhibited high M^(pro)inhibitory activity in molecular docking and its IC_(50)value was 139.40±0.82μmol/L in vitro according to fluorescence resonance energy transfer assay(FRET).Quantitative real-time(qRT-)PCR results show that SSGFID could stimulate the expression of mitosis-related factors,including nuclear factor-κB,cyclin D1,and cyclin-dependent kinase 4,to promote the proliferation of mice splenocytes.Stability study revealed that SSGFID showed resistance against pepsin and trypsin but lost D(Asp)after pretreatment at121℃ for 15 min.Besides,SSGFID was mainly transported through the Caco-2 cell monolayer by the peptide transporter PepT1 and passive-mediated transport during the transport study.Unfortunately,the peptide was also degraded by Caco-2 intracellular enzymes,and the transfer rate of intact peptide was4.2%.Furthermore,Lineweaver–Burk plots demonstrated that SSGFID possessed a mixed inhibitory characteristic with M^(pro).Our study indicated the potential of Ulva prolifera as antiviral and immuneenhancing functional food ingredients and nutraceuticals.

Study of screening,transport pathway,and vasodilation mechanisms on angiotensin-Ⅰconverting enzyme inhibitory peptide from Ulva prolifera proteins

In this study,Ulva prolifera protein was used for preparing angiotensin-I converting enzyme(ACE)-inhibitory peptide via virtual gastrointestinal digestion and in silico screening.Some parameters of the obtained peptide,such as inhibition kinetics,docking mechanism,stability,transport pathway,were explored by Lineweaver-Burk plots,molecular docking,in vitro stimulate gastrointestinal(GI)digestion and Caco-2 cells monolayer model,respectively.Then,a novel anti-ACE peptide LDF(IC_(50),(1.66±0.34)μmol/L)was screened and synthesized by chemical synthesis.It was a no-competitive inhibitor and its anti-ACE inhibitory effect mainly attributable to four Conventional Hydrogen Bonds and Zn701 interactions.It could keep activity during simulated GI digestion in vitro and was transported by peptide transporter PepT1 and passive-mediated mode.Besides,it could activate Endothelial nitric oxide synthase(eNOS)activity to promote the production of NO and reduce Endothelin-1(ET-1)secretion induced by AngiotensinⅡ(AngⅡ)in Human Umbilical Vein Endothelial Cells(HUVECs).Meanwhile,it could promote mice splenocytes proliferation in a concentration-dependent manner.Our study indicated that this peptide was a potential ingredient functioning on vasodilation and enhancing immunity.

Ulva prolifera subpixel mapping with multiple-feature decision fusion

The unavoidable nature of Ulva prolifera mixed pixel in low-resolution remote sensing images would result in rough boundary of U.prolifera patches,omission of tiny patches,and overestimation of coverage area.The decomposition of U.prolifera mixed pixel addresses the issue of coverage area overestimation,and the remaining problems can be alleviated by subpixel mapping(SPM).Due to the drift and dissipation of U.prolifera,a suitable SPM method is the single image-based unsupervised method.However,the method has difficulties in detail reconstruction,insufficient learning of spectral information,and SPM error introduced by abundance deviation.Therefore,we proposed a multiple-feature decision fusion SPM(MFDFSPM)method.It involves three branches to obtain the spatial,abundance,and spectral features of U.prolifera while considers multi-feature information using the fusion strategy.Experiments on the Geostationary Ocean Color Imager images in the Yellow Sea of China indicate that the MFDFSPM overperforms several typical U.prolifera SPM methods in higher accuracy and stronger robustness in both SPM and abundance calculation,which produced subpixel map with more detailed spatial information and less noise.

Effects of Ulva prolifera dissipation on the offshore environment based on remote sensing images and field monitoring data

Outbreaks of Ulva prolifera have continued in the South Yellow Sea of China(SYS)since 2007,becoming a serious marine ecological disaster.Large amounts of U.prolifera drift to the coast of the Shandong Peninsula to dissipate under the action of southeast monsoons and ocean surface currents.This causes serious harm to the ecological environment and economic activities of coastal cities.To investigate the impact of U.prolifera dissipation,this study extracted the spatiotemporal distribution of U.prolifera in the SYS from 2012 to 2020 based on the Google Earth Engine.The outbreak cycle of U.prolifera was determined by fitting analysis of outbreak time and coverage area through MATLAB.This study also looked at the effect of U.prolifera dissipation on water quality through field monitoring data.The results showed that the growth curve of the U.prolifera has a significant Gaussian distribution.The U.prolifera dissipates in Haiyang,China,in July and August every year and affects the offshore environment.Water quality parameters of seawater at different depths had significant differences after the U.prolifera dissipation.Changes in pH,chemical oxygen demand,nitrite nitrogen,nitrate nitrogen,ammonia nitrogen,chlorophyll a,total phosphorus,and suspended solids were more significant in surface seawater than in deeper water.Changes in the concentrations of dissolved oxygen and total nitrogen were more significant in the deep seawater(1.63 and 1.1 times higher than those in the surface seawater,respectively).The dissipation of U.prolifera releases a large amount of carbon and nitrogen into the seawater,which provides rich nutrients for phytoplankton and may cause secondary disasters such as red tide.These findings are useful for further understanding the rules of U.prolifera dissipation,as well as preventing and controlling green tide disasters.

Structure of Ulvan Isolated from the Edible Green Seaweed, Ulva pertusa

Ulvan, rhamnan sulfate, was extracted from the edible green seaweed, Ana-aosa (Ulva pertusa), which is grown on the coast of the Okinawa Islands. The yield of ulvan was 8.5% (W/W), and the total carbohydrates, uronic acid and sulfuric acid and ash contents were 67.3%, 23.8%, 19.7% and 22.6%, respectively. L-Rhamnose, D-xylose and D-glucose residues were identified by liquid chromatography, and their molar ratio was 4.0:0.1:0.3. D-Glucuronic and L-idulonic acid residues were also identified in molar ratio of 1.0:0.2. The NMR (13C and 1H) and methylation analysis revealed terminal β-D-glucruonic acid, terminal α-L-idulonic acid, 1,3-linked α-L-rhamnose, 1,4-linked α-L-rhamnose, 1,2,4-linked α-L-rhamnose, 1,3,4-linked α-L-rhamnose, 1,2,3,4-linked α-L-rhamnose and 1,3,4-linked β-D-xylose. The sulfate groups were attached at the C-2 and C-3 positions of the 1,4-linked α-L-rhamnose as well as C-3 of the 1,4-linked β-D-xylose residues. The chemical structure of the ulvan from Ulva pertusa was determined.

Photosynthetic Responses to Inorganic Carbon in Ulva lactuca Under Aquatic and Aerial States

Intertidal macroalgae experience continual alternation of photosynthesis between aquatic state at high tide and aerial state at low tide. The comparative photosynthetic responses to inorganic carbon were investigated in the common intertidal macroalga Ulva lactuca L. along the coast of Shantou between aquatic and aerial state. The inorganic carbon dissolved in seawater at present could fully (at 10 ℃ or 20 ℃) or nearly (at 30 ℃) saturate the aquatic photosynthesis of U. lactuca . However, the aerial photosynthesis was limited by current ambient atmospheric CO 2 level, and such a limitation was more severe at higher temperature (20-30 ℃) than at lower temperature (10 ℃). The carbon_saturated maximal photosynthesis of U. lactuca under aerial state was much greater than that under aquatic state at 10 ℃ and 20 ℃, while the maximal photosynthesis under both states was similar at 30 ℃. The aerial values of K m (CO 2) for photosynthesis were higher than the aquatic values. On the contrary, the values of apparent photosynthetic CO 2 conductance under aerial state were considerably lower than that under aquatic state. It was concluded that the increase of atmospheric CO 2 would enhance the primary productivity of U. lactuca through stimulating the photosynthesis under aerial state during low tide.

Comparative chloroplast genomes of Ulva prolifera and U.linza(Ulvophyceae)provide genetic resources for the development of interspecific markers

The green seaweeds Ulva linza and U.prolifera are closely related species.They usually co-occur widely and have important ecological significance as primary producers thriving in the intertidal zone.In the Yellow Sea,a genetically unique floating ecotype of U.prolifera even bloomed to cause serious green tides.However,there is still a lack of appropriate molecular markers to distinguish these two species,partially due to limited evaluations on the intraspecific variations in U.prolifera among dif ferent ecotypes.Since organelle genomes could provide rich genetic resources for phylogenetic analysis and development of genetic markers,in this study,the chloroplast genome from one attached population of U.prolifera was completely sequenced,and comparative genomic analyses were performed with other existing chloroplast genomes from U.linza and the floating ecotype of U.prolifera.The results showed that in spite of the high level of collinearity among three genomes,there were plenty of genetic variations especially within the non-coding regions,including introns and gene spacer regions.A strategy was proposed that only those signals of variation,which were identical between two ecotypes of U.prolifera but divergent between U.linza and U.prolifera,were selected to develop the interspecific markers for U.linza and U.prolifera.Two candidate markers,psa B and pet B,were shown to be able to distinguish these two closely related species and were applicable to more attached populations of U.prolifera from a wide range of geographical sources.In addition to the interspecific marker,this study would also provide resources for the development of intraspecific markers for U.prolifera.These markers might contribute to the surveys for Ulva species composition and green tide monitoring especially in the Yellow Sea region.

浒苔(Ulva prolifera)漂浮生态型的分枝表型及其可塑性

黄海绿潮由浒苔漂浮生态型主导,普遍认为其具有高度分枝的表型特征,但始终缺乏形态学的量化表征。本研究针对浒苔的分枝表型,通过广泛采集漂浮生态型与定生群体样本,使用最高分枝级数和一级分枝密集度两个形态学指标进行了量化表征,结果表明,定生浒苔普遍仅有一级分枝或无分枝,而漂浮生态型分枝级数最高可达五级,其一级分枝密集度是定生浒苔的5.8倍,说明漂浮生态型的分枝程度显著高于定生浒苔。另外,无论自然条件还是人工培养条件下,发现漂浮生态型分枝表型的可塑性也明显强于定生群体。上述结果提示,高度分枝表型是漂浮生态型重要的漂浮适应性特征;而分枝表型的强可塑性,可能有助于其适应漂浮过程中多变的海洋环境。上述结论可为后续深入研究提供形态学量化指标和重要理论依据。

浒苔(Ulva prolifera)共附生细菌群落结构分析的引物优化

海藻共附生细菌密切参与宿主的生长发育、营养吸收等重要过程,浒苔(Ulva prolifera)是构成黄海绿潮的唯一优势种,对其共附生细菌开展群落结构分析,有望为成灾机制研究提供重要线索。由于植物叶绿体基因组同时具备原核特征和高拷贝数,会严重干扰共附生细菌基于16S rDNA的序列扩增。高等植物中开发了通用引物799F,利用其3′末端与植物同源区的非配对双碱基,可实现对细菌来源序列的特异性扩增。本文针对多个浒苔群体样本,首次评价了引物799F在藻类中的适用性,发现799F的3′末端与浒苔叶绿体同源区仅存在非配对单碱基,其扩增仍会受到浒苔叶绿体严重干扰。在引物799F的基础上,设计了新引物800F,与通用反向引物1492R配对扩增细菌16S rDNA中具高分辨率的V5-V9可变区,配合使用具热启动功能、同时不具校对功能的DNA聚合酶,可基本完全避免浒苔叶绿体来源序列的扩增,并阐明了方法的原理。优化的引物扩增方案可用于浒苔共附生细菌群落结构分析。

外源CaCl_(2)调控浒苔(Ulva prolifera)高温逆境的比较转录组研究

钙(Ca^(2+))作为一种必需的信号分子,在植物的生长发育和非生物胁迫调节中起着至关重要的作用。本实验采用BGISEQ平台进行高通量测序,获得浒苔外源CaCl_(2)添加(UpCa)和高温对照(UpHT)处理下相关的转录组数据,分析了在高温(35℃)下外源CaCl_(2)的添加转录组的变化。结果显示,根据UpHT和UpCa处理分析共获得36625条基因;与UpHT相比,在UpCa下鉴定出7513个差异表达的基因,包括6002个上调基因,1151个下调基因,对差异基因进行了GO富集和KEGG富集分析。对膜转运、植物信号转导和环境适应性相关的差异基因进行KEGG富集分析,主要富集在内吞(Endocytosis)、植物病原菌互作(Plant-pathogen interaction)、丝裂原激活的蛋白激酶信号通路(MAPK signaling pathway-plant)、植物激素的信号传递(Plant hormone signal transduction)、ABC转运(ABC transporters)和磷脂酰肌醇信号系统(Phosphatidylinositol signaling system)等代谢通路上。植物激素信号转导途径中,细胞分裂素、脱落酸、油菜素内酯和乙烯信号转导途径增强。抗氧化酶中FeSOD、谷胱甘肽过氧化物酶、谷胱甘肽S转移酶和抗坏血酸过氧化物酶等基因表达上调,下调的基因主要是热激蛋白。Ca^(2+)信号组分基因钙结合蛋白、钙调素、钙/钙调素依赖的蛋白激酶以及钙/钙调蛋白依赖性3′,5′环核苷酸磷酸二酯酶的基因表达上调,丝裂原活化蛋白激酶激酶激酶和磷脂酰肌醇信号相关的基因也差异性上调。本研究系统阐述了植物信号转导、抗氧化酶、MAPK信号系统以及Ca^(2+)信号组分基因在外源CaCl2对浒苔高温压力的调节中的重要作用,可为进一步阐明Ca^(2+)信号对高温的调节适应机制提供理论基础。

石莼属(Ulva)和浒苔属(Enteromorpha)绿藻的RAPD分析

于 1 997年下半年在大连石庙海区采集石莼、孔石莼、砺菜、缘管浒苔、肠浒苔、管浒苔、刚毛藻等 7种海藻样品 ,采用RAPD技术对大连地区绿藻门石莼属和浒苔属进行了初步的分子系统学研究。所试 60个引物中有 32个经扩增得到了 2 37个多态片段。应用PHYLIP软件包 ,按照UPGMA法和N -J法聚类分析的结果均表明 ,缘管浒苔 (Enteromorphalinza)与石莼属有较近的亲缘关系 ,应深入探究其分类地位。

盐度、光照和营养盐对孔石莼(Ulva pertusa)光合作用的影响

通过测定光合作用产氧速率研究了孔石莼 Ulva pertusa不育性变种在不同盐度、光强度和营养盐水平下的光合作用特性。结果表明 ,盐度可影响光合作用速率 ,在 2 71 0 lx光强下孔石莼在盐度 2 0‰左右有最大光合作用速率 ;光合作用参数 Pm为 79.62 O2 ,μg/cm2 · h,Is为 1 91 .0 8μE/m2 · s,IC为 1 0 .1 2μE/m2 · s;对营养盐 ( NH4 +-N,NO2 - -N,PO4 3- -P)的吸收特征可用 Michaelis-Menten方程描述 ,低光强 ( 1 0 6lx)下氨氮超过 0 .0

不同温度与营养盐条件对浒苔(Ulvaprolifera)和肠浒苔(Ulvaintestinalis)的生长影响

2010年4月采集了江苏省南通市如东县紫菜养殖筏架上的浒苔（Ulva prolifera）和肠浒苔（Ulva intestinalis）样品，对两种浒苔在不同温度和营养盐环境下的生长情况进行了研究，分析了其不同生长特点及对环境变化的响应。结果表明，浒苔（U. prolifera）在15℃~25℃范围内，在浓度相对较高的营养盐组相对生长率较高。肠浒苔（U. intestinalis）在温度为10℃~20℃范围内，在浓度较低的营养盐组相对生长率较高。在两种浒苔相对生长率达到最大的同时，其对于营养盐的消耗量也达到最大。据此，推测两种浒苔自身的生理生态特征及其对环境变化的响应是影响其生物量的重要因素。

不同体系改性粘土对浒苔(Ulva prolifera)微观繁殖体去除及萌发的影响

本文研究了2种无机改性粘土在3种不同改性配比下对浒苔微观繁殖体去除效果及萌发的影响。结果发现,去除率随改性粘土及改性剂用量的增加而升高,相同条件下硫酸铝(AS)改性粘土对浒苔微观繁殖体的去除效果优于聚合氯化铝(PAC)改性粘土,其中1∶5PAC改性粘土在0.5g/L时去除率为62%,AS改性粘土则可达到80%。添加改性粘土后上层水体中浒苔微观繁殖体相对萌发率随改性粘土及改性剂用量的升高而降低,总体系相对萌发率表现为先升后降趋势,在改性剂浓度为0.1g/L时相对萌发率达到最高。两种改性体系中微观繁殖体在1∶3配比、1.0g/L浓度下均未能萌发。该结果显示,改性粘土可以有效去除浒苔微观繁殖体并抑制其萌发,这为我国绿潮灾害的防控提供了一种新思路。

孔石莼(Ulva pertusa Kjellm)调血脂作用的初步研究

观察孔石莼热水提取多糖和孔石莼乙醇提取物中的有效部位对小鼠实验性高脂血症水平的影响 ,发现孔石莼多糖 2 5 0、5 0 0和 10 0 0mg/ (kg·d)三个剂量组均具有降低小鼠血清总胆固醇 (TC)、甘油三酯 (TG)和低密度脂蛋白胆固醇 (LDL C)的作用 ,而高剂量组具有一定升高高密度脂蛋白胆固醇 (HDL C)的作用 ,其增加HDL C/TC比值显著 (P <0 0 5 )。孔石莼乙醇提取物中的有效部位也具有降低血清TC、TG和LDL C的作用 ,其降TC的作用稍次于孔石莼多糖 ,但其降低TG、升高HDL C/TC比值的作用优于孔石莼多糖。

孔石莼(Ulva pertusa)对铅、铜、镉的吸收

研究了大型藻孔石莼对铅、铜和镉的吸收动力学和热力学过程。结果表明,暴露于不同浓度的重金属体系中的孔石莼对铅、铜和镉的积累量随着水相中的游离态浓度的增加而增加,可以用Langmuir吸附等温式从热力学平衡角度加以描述,铅和镉饱和结合量分别为:0.715 mg/g干重,Cd2+为0.037 mg/g干重;在孔石莼对铜(0.056 mg/L)吸收动力学浓度的实验中,第4天达到了吸收平衡,蓄积量为对照组的9.01倍;在镉暴露浓度为0.028 mg/L的实验中,第5天达吸收平衡,蓄积量为对照组的5.06倍。