Inhibition of photosynthesis in the microalga Chaetoceros curvisetus （Bacillariophyta） by macroalga Gracilaria lemaneiformis （Rhodophyta）

We investigated the effects of dried macroalga Gracilaria lemaneiform （Rhodophyta） on photosynthesis of the bloom-forming microalga Chaetoceros curvisetus. C. curvisetus was cultured with different amounts of dried G. lemaneiformis under controlled laboratory conditions. We measured the photosynthetic oxygen evolution rate and established the chlorophyll a fluorescence transient （OJIP） curve coupled with its specific parameters. We observed concentration-dependent and time-dependent relationships between dried G. lemaneiformis and inhibition of photosynthesis in C. curvisetus. Co-culture with dried G. lemaneiformis also resulted in a decrease in the light-saturated maximum photosynthetic oxygen evolution rate （P~ax） in C. curvisetus, and a decrease in the OJIP curve along with its specific parameters; the maximum photochemical efficiency of PSII （FJFm）, the amount of active PSII reaction centers per excited cross section at t=0 and t=--tFM （RC/CS0 and RC/CSm, respectively）, the absorption flux per excited cross section at t=0 （ABS/ CS0）, and the efficiency with which a trapped exciton moves an electron into the electron transport chain （~u0）. The dark respiration rate （Rd） increased in C. curvisetus co-cultured with dried G. lemaneiformis. The JIP-test and the oxygen evolution results indicated that dried G. lemaneiJbrmis decreased the number of active reaction centers, blocked the electron transport chain, and damaged the oxygen-evolving complex of C. curvisetus. This result indicated that dried fragments of G. lemaneiformis could effectively inhibit photosynthesis of C. curvisetus, and thus, could serve as a functional product to control and mitigate C. curvisetus blooms.     

日本凋毛藻碳酸酐酶基因及其编码的蛋白特征

碳酸酐酶CA(EC 4.2.1.1)是含锌原子的金属蛋白酶,该酶的基本功能是催化CO₂与HCO₃-间的相互转换[1].该反应在许多生物过程中都发挥着重要的作用,例如离子交换、呼吸作用、pH稳定性、捕获CO₂和光合作用等[2~5].CA广泛分布于各种生物中,已知的CA酶根据氨基酸序列被分为-αCA,-βCA和γ-CA三种类型[5~7].这3种类型的CA酶序列间的相似性很低,被认为是由不同的途径进化而来的[7].α-型的CA酶在动物、植物、绿藻、细菌和蓝细菌中都有发现[7],在藻类中报道的α-型CA还很少.迄今为止只在衣藻中发现2种异构体,在盐藻中发现3种[8,9],在红藻中还未见报道.     

西沙群岛红藻研究Ⅲ

本文继续报道我国西沙群岛产的十种红藻，其中梨形葡萄藻[Botryocladia pyriformis (Boergesen) Kylin]，聚集腔节藻(Coelarthrum coactum Okam. et Segawa)，渐狭下舌藻(Hypoglossum attenuatum Gardner)，棍棒内管藻[Endosiphonia clavigera (Wolny) Falkenberg],匍甸软骨藻(Chondria repens Boergesen)和扩展软骨藻(Chondria expansa Okam.)等六种为我国新记录；西沙软骨藻(Chondria xishaensis sp. nov.)为一新种;矮孔果藻和梨形葡萄藻的四分孢子囊均为首次记述。     

红藻DNA条形码分析技术研究进展

DNA条形码是指利用一段相对较短的标准DNA片段,对物种进行识别和鉴定。目前该技术在动物、植物物种鉴定领域已经得到了广泛的研究和应用。在藻类的研究中,尚未确定一条统一的标准条形码基因,现阶段都是使用2条或2条以上基因序列来完成物种鉴定。对于形态多样、种类繁多的海洋红藻,常用的DNA条形码基因有COI基因(Partial cytochrome c oxidase I gene)、UPA基因(Partial 23SrRNA gene,universal plastid amplicon)、LSU基因(Partial 28SrRNA gene)和rbcL基因(The large subunit of ribulose-1,5-bisphosphate carboxylase)等,这些基因中2个或3个基因的互补运用准确有效地提高了红藻的鉴定准确率,尤其是COI基因的种间差异大足够区分相近物种。本文在概述条形码的原理及其标准的基础上,阐述了红藻DNA条形码鉴定研究的新进展以及常用几种基因片段的优缺点,并对条形码在红藻鉴定中存在的问题进行了分析,对其应用前景进行了展望。     

11-deoxyheloside A的合成

首次完成天然胆甾烷型皂苷11-deoxyheloside A的合成。在相转移催化的条件下,葡萄糖溴苷1与膦酸单乙酯2反应以69%的收率得到葡萄糖膦酸酯供体3;以胆甾烷苷元4为原料,经Luche还原和乙酰化反应以及三氟甲磺酸负载硅胶脱除TBDPS基团得到胆甾烷二醇10;在金催化剂的作用下,胆甾二醇10与葡萄糖膦酸酯供体3进行糖苷化反应,然后脱除酰基保护基以97%的产率完成11-deoxyheloside A的合成。     

一种适合于红藻的总RNA提取方法

以5种红藻(条斑紫菜(Porphyra yezoensis),日本多管藻(Polysiphonia japonica),长心卡帕藻(Kappaphycus alvarezii),扇形叉枝藻(Gymnogongrus ftabelliformis),带形蜈蚣藻(Grate-loupia turuturu))为实验材料,为了获得高质量的总RNA,比较了Trizol法、试剂盒法、CTAB法和Trizol+纯化柱法。结果显示:Trizol+纯化柱法对5种红藻总RNA的提取均取得了良好的效果。经琼脂糖凝胶电泳检测,所提取的总RNA 28S、18S条带清晰明亮,无降解;A260/A280、A260/A230值均符合要求,表明提取的总RNA质量较好;利用提取的总RNA进行RT-PCR扩增actin基因的保守片段,能够获得约550bp的目的片段,进一步表明Trizol+纯化柱法是适合于红藻总RNA提取的方法。     

运用nrDNA ITS 数据研究角叉菜属(Chondrus)在红藻门中的系统进化地位

测定了角叉菜属(Chondrus)5个代表种的核糖体DNA内转录间隔区(ITS)及5.8SrDNA基因序列。结果表明,角叉菜属ITS区(含ITS1、5.8SrDNA和ITS2)序列长度范围为704—714bp,G+C含量为44.6%—45.7%,变异位点69个,信息位点16个;其中,ITS1和ITS2的长度范围分别为147—149bp和398—404bp。5.8SrDNA长度为158bp,没有变异和信息位点。由MEGA3构建的系统进化树(ME和MP)显示:在进化尺度上,真红藻纲的松节藻科(Rhodomelaceae)与红毛菜纲(Bangiophyceae)亲缘关系较近。在真红藻纲内,杉藻目(Gigartinales)的进化地位相对较高,其次是海膜科(Halymeniaceae)、石花菜科(Gelidiaceae)、红叶藻科(Delesseriaceae)和粉枝藻科(Liagoraceae)等,而松节藻科进化地位相对较低。在杉藻目内,杉藻科(Gigartinaceae)和胶黏藻科(Dumontiaceae)进化关系密切,而形态学特征相似的角叉菜和马泽藻(Mazzaella)亲缘关系非常近。     

Phylogenomic analysis of transcriptomic sequences of mitochondria and chloroplasts for marine red algae (Rhodophyta) in China

The chloroplast and mitochondrion of red algae （Phylum Rhodophyta） may have originated from different endosymbiosis. In this study, we carried out phylogenomic analysis to distinguish their evolutionary lin-eages by using red algal RNA-seq datasets of the 1 000 Plants （1KP） Project and publicly available complete genomes of mitochondria and chloroplasts of Rhodophyta. We have found that red algae were divided into three clades of orders, Florideophyceae, Bangiophyceae and Cyanidiophyceae. Taxonomy resolution for Class Florideophyceae showed that Order Gigartinales was close to Order Halymeniales, while Order Graci-lariales was in a clade of Order Ceramials. We confirmed Prionitis divaricata （Family Halymeniaceae） was closely related to the clade of Order Gracilariales, rather than to genus Grateloupia of Order Halymeniales as reported before. Furthermore, we found both mitochondrial and chloroplastic genes in Rhodophyta under negative selection （Ka/Ks〈1）, suggesting that red algae, as one primitive group of eukaryotic algae, might share joint evolutionary history with these two organelles for a long time, although we identified some dif-ferences in their phylogenetic trees. Our analysis provided the basic phylogenetic relationships of red algae, and demonstrated their potential ability to study endosymbiotic events.     

红藻碳代谢的研究进展

红藻门(Rhodophyta)在全世界约有760属,4 410种,绝大多数海产,少数生于淡水,分布于各地,包括极地.中国已知有127属,300种,分布于南北各海区,淡水种类极少.     

赤潮灾害及应急措施

赤潮又叫红潮,是海洋表层红藻等浮游生物暴发性繁殖引起水色异常和水质恶化的一种现象。近海海域．藻类浮游生物因水质变化和养分提高而大量繁殖．在阳光照射下呈现大片红色。因主要生物种类不同,还可能出现褐色、黑色、黄色等。