Involvement of cyclic electron flow in irradiance stress responding and its potential regulation of the mechanisms in <Emphasis Type="Italic">Pyropia yezoensis</Emphasis>

Pyropia yezoensis, belongs to the genus of Porphyra before 2011, inhabit on intertidal zone rocks where irradiation changes dramatically, implying that the seaweed has gained certain mechanisms to survive a harsh environment. Based on the photosynthetic parameters with or without the inhibitors determined by a Dual-PAM-100 apparatus, we investigated the photosynthetic performance and the changes in electron flow that occurred during the algae were stressed with different light intensities previously. When the irradiation saturation was approaching, the CEF around PS I became crucial since the addition of inhibitors usually led to an increase in non-photochemical quenching. The inhibitor experiments showed that there were at least three different CEF pathways in Py. yezoensis and these pathways compensated each other. In addition to maintaining a proper ratio of ATP/NAD(P)H to support efficient photosynthesis, the potential roles of CEF might also include the regulation of different photoprotective mechanisms in Py. yezoensis. Under the regulation of CEF, chlororespiration is thought to transport electrons from the reduced plastoquinone (PQ) pool to oxygen in order to mitigate the reduction in the electron transfer chain. When irradiation was up to the high-grade stress conditions, the relative value of CEF began to decrease, which implied that the NADP⁺ pool or PQ⁺ pool was very small and that the electrons were transferred from reduced PS I to oxygen. The scavenging enzymes might be activated and the water-water cycle probably became an effective means of removing the active oxygen produced by the irradiation stressed Py. yezoensis. We believe that the different mechanisms could make up the photoprotective network to allow Py. yezoensis for survival in a highly variable light stress habitat, which may enlighten scientists in future studies on irradiance stress in other algae species.     

Characterization of a new lectin involved in the protoplast regeneration of <Emphasis Type="Italic">Bryopsis hypnoides</Emphasis>

A group of coenocytic marine algae differs from higher plants,whose totipotency depends on an intact cell(or protoplast).Instead,this alga is able to aggregate its extruded protoplasm in sea water and generate new mature individuals.It is thought that lectins play a key role in the aggregation process.We purified a lectin associated with the aggregation of cell organelles in Bryopsis hypnoides.The lectin was ca.27 kDa with a pI between pH 5 and pH 6.The absence of carbohydrate suggested that the lectin was ...     

青岛奥帆基地海域漂浮浒苔光合生理特点研究

研究了青岛奥帆基地海域漂浮浒苔Enteromorpha prolifera （Muell）J.Ag.色素组成及含量、光合放氧及呼吸耗氧速率、P／R（净光合放氧速率／净呼吸耗氧速率）、抗氰呼吸等各项生理指标。结果表明，该海域漂浮浒苔的各项生理指标都在正常范围内，且有抗氰呼吸的存在，生长状况良好。     

Analysis of expressed sequence tags from the Ulva prolifera (Chlorophyta)

In 2008,a green tide broke out before the sailing competition of the 29th Olympic Games in Qingdao.The causative species was determined to be Enteromorpha prolifera (Ulva prolifera O.F.Müller),a familiar green macroalga along the coastline of China.Rapid accumulation of a large biomass of floating U.prolifera prompted research on different aspects of this species.In this study,we constructed a nonnormalized cDNA library from the thalli of U.prolifera and acquired 10 072 high-quality expressed sequence tags ...     

Optimization of conditions for tetraspore release and assessment of photosynthetic activities for different generation branches of Gracilaria lemaneiformis Bory

Gracilaria lemaneiformis Bory is an economically important alga that is primarily used for agar production. Although tetraspores are ideal seeds for the cultivation of G. lemaneiformis, the most popular culture method is currently based on vegetative fragments, which is labor-intensive and time-consuming. In this study, we optimized the conditions for tetraspore release and evaluated the photosynthetic activities of different colonies formed from the branches of G. lemaneiformis using a PAM (pulse-amplitude-modulated) measuring system. The results showed that variations in temperature and salinityhad significant effects on tetraspore yield. However, variations in the photon flux density (from 15 μmol m⁻² s⁻¹ to 480 μmol m⁻² s⁻¹) had no apparent effect on tetraspore yield. Moreover, the PAM-parameters Y(I), Y(II), ETR(I), ETR(II) and F _v/F _m of colonies formed from different branches showed the same trend: parameter values of first generation branches>second generation branches>third generation branches. These results suggest that the photosynthetic activities of different colonies of branches changed with the same trend. Furthermore, photosynthesis in G. lemaneiformis was found to be involved in vegetative reproduction and tetraspore formation. Finally, the first generation branches grew slowly, but accumulated organic compounds to form large numbers of tetraspores. Taken together, these results showed that the first generation branches are ideal materials for the release of tetraspores.     

条斑紫菜低覆盖度基因组草图分析

对条斑紫菜（Porphyra yezoensis）进行Solexa高通量测序,获得低覆盖度全基因组草图。该基因组草图大小约220Mbp,GC质量分数53．08％;包含26629个预测基因,其中16409个基因具有内含子,平均每个基因含2．22个内含子;基因结构分析表明具有内含子的基因平均长度为2214bp,内含子平均大...     

绿潮生物学机制研究

绿潮发生机制极其复杂,但其核心机理是绿潮暴发时漂浮"藻席"中的浒苔快速形成巨大生物量,涉及浒苔生物学过程对环境的响应及其生理生化基础。为此,本文在已有研究报道的基础上,对浒苔生活史研究进行了充分的理论补遗;分析了漂浮"藻席"中浒苔生长与繁殖过程,认为该过程是绿潮生物量形成的关键;阐述了浒苔孢子囊形成是对富营养化背景下海水溶解无机氮(DIN)中硝态氮高占比的响应,认为一氧化氮分子可促进浒苔营养细胞向孢子囊的转化;解析了浒苔细胞对逆境因子的响应途径与机制。基于已有的研究成果,本文对浒苔引发绿潮的生物学过程进行了理论推定。人为或自然因素使固着浒苔处于漂浮状态,形成小规模"藻席";富营养化背景下海水DIN中硝态氮占比的升高赋予了浒苔巨大的繁殖潜能,漂浮过程溶解无机碳(DIC)"充裕"和"不足"两个阶段的交替以及食藻动物啃食产生的藻片段使孢子囊形成比例大幅提升;孢子原位萌发等使释放的孢子在"藻席"中获得了附着基,个体数目随之指数增长;结合漂浮浒苔的高生长速率,"藻席"规模不断扩大,短时间内形成巨大生物量。同时,本文还对今后的绿潮研究提出一些建议,认为啃食动物在浒苔生物量消长过程中发挥重要作用,在漂浮"藻席"系统中扮演着"生态引擎"的功能,同时系统阐明浒苔孢子的原位萌发等现象的生物学机理应该是未来绿潮的重要研究内容。     

坛紫菜碳酸酐酶基因的克隆、表达及酶活性分析

以坛紫菜丝状体为材料,采用RACE方法获得坛紫菜碳酸酐酶(CA)基因的全长cDNA。该cDNA全长1 081 bp,具有一个825 bp的开放阅读框,可编码274个氨基酸。序列同源性分析显示该cDNA序列推导的氨基酸序列与其他物种的碳酸酐酶具有较高的一致性,其中与条斑紫菜的一致性达到96%。氨基酸序列分析表明该蛋白为β-CA,含有两个CA活性位点,无跨膜结构,可能存在一个信号肽将其定位到叶绿体中,与藻类和细菌聚类。原核诱导表达得到一个72 kDa左右的融合蛋白,酶活测定结果显示此蛋白具有碳酸酐酶活性。该实验对进一步深入研究坛紫菜CA的功能及坛紫菜碳代谢、光合作用等生理过程具有重要的参考价值。     

脱落酸介导的逆境响应信号传导机制及在藻类中的分布与功能研究

植物激素是一类由植物合成的痕量有机物质,调控着植物的生长发育及对环境的适应。藻类属低级植物类群,且具有与高等植物类似的大多数激素类型,相对而言,藻类激素含量更少,却发挥着更高效的生理活性。无论在藻类,还是高等陆地植物,胁迫响应一直是研究十分活跃的领域。其中脱落酸(ABA)作为应激激素,所起的调节作用已得到人们的共识。本文总结了近些年关于ABA在藻类中的分布,ABA对抗氧化酶系的调控,ABA信号传导路径在陆地植物中的发现与代谢机制,以及利用蛋白质分子系统学对ABA信号传导途径的起源与进化的分析。在此基础上,提出未来藻类ABA参与的抗逆代谢调控研究应着重从潮间带海藻出发,参考陆地植物研究的成果,应用生物信息学结合生物化学等的手段,进行相关机制的探索。     

Variation in Rubisco and other photosynthetic parameters in the life cycle of Haematococcus pluvialis

Cells of Haematococcus pluvialis Flot. et Will were collected in four different growth phases. We quantified the initial and total enzyme activity of ribulose-1,5-bisphosphate carboxylase (Rubisco) in crude extracts, and the relative expression of large-subunit ribulose-1,5-bisphosphate caboxylase / oxygenase (rbcL) mRNA. We measured the ratio of photosynthetic rate to respiration rate (P/R), maximal effective quantum yield of photosystem II (Fv/Fm), electron transport rate (ETR), actual photochemical efficiency of PSII in the light (ΦPSII), and non-photochemical quenching (NPQ). Green vegetative cells were found to be in the most active state, with a relatively higher P/R ratio. These cells also displayed the lowest NPQ and the highest Fv/Fm, ETR, and ΦPSII, indicating the most effective PSII. However, both Rubisco activity and rbcL mRNA expression were the lowest measured. In orange resting cysts with relatively lower P/R and NPQ, Rubisco activity and rbcL expression reached a peak, while Fv/Fm, ETR, and ΦPSII were the lowest measured. Taking into account the methods of astaxanthin induction used in industry, we suggest that Rubisco may participate in astaxanthin accumulation in H. pluvialis. A continuous and sufficient supply of a carbon source such as CO2 may therefore aid the large scale production of astaxanthin.