Expressed sequence tags analysis revealing the taxonomic position and fatty acid biosynthesis in an oleaginous green microalga,Myrmecia incisa Reisigl(Trebouxiophyceae,Chlorophyta)  

作　　者：OUYANG LongLing DU DaoHai YU ShuiYan LI ChunYang ZHANG ChengWu GAO HongJian ZHOU ZhiGang 

机构地区：[1]Key Laboratory of Genetic Resources and Utilization in Aquaculture, Shanghai Ocean University, Shanghai 201306, China [2]College of Life Sciences, Ji'nan University, Guangzhou 210009, China [3]Shanghai Medical College of Fudan University, Shanghai 200030, China

出　　处：《Chinese Science Bulletin》2012年第25期3342-3352,共11页

基　　金：supported by the National Natural Science Foundation of China (30972243);the Creative Project of the Shanghai Municipal Education Committee (09ZZ167);the National High Technology Research and Development Program of China (2009AA064401);the Key Discipline Project of the Shanghai Municipal Education Committee (J50701);Excellent Thesis Grant from Shanghai Ocean University

摘　　要：cDNA library of Myrmecia incisa H4301 was constructed using λ phage vectors.The library consisted of 1.5×10 6 clones with a recombination rate of 90%,and 1942 clones were randomly sequenced.All 1854 readable expressed sequence tags(ESTs) were clustered into 596 non-redundant sequences(NRSs),among which 126 NRSs were from 1384 ESTs,showing a high redundancy.Among the 596 NRSs,30 were ribosomal RNA,and 152 significantly matched with those available in NCBI database and JGI Genome Portal,the latter were divided into nine subcategories.Overall,59 NRSs were involved in photosynthesis,the respiratory electron transport chain,ATP synthesis,oxidation reduction,fatty acid biosynthesis,glucose metabolism,protein metabolism,and small molecular metabolism,suggesting that these genes were abundantly transcribed during energy and substance metabolism.Acyl-carrier protein,ferrodoxin and fatty acid elongase genes obtained from this cDNA library enabled presumption of a possible biosynthesis pathway of ArA in M.incisa.Codon usage analysis of 142 NRSs with 17798 codons in the predicted coding regions showed that the average G+C content level of the total codons was 55.39%,and that of the third position in base trimers was 66.42%,indicating a strong bias toward cytosine and/or guanosine in this algal genome.Among all synonymous codons,NAG was most favored,while NUA was most avoided.Phylogenic trees inferred from ribulose-1,5-bisphosphate carboxylase/oxygenase small subunit genes and the extra partial sequences of 18S rRNA obtained from this library demonstrated that M.incisa belonged to Trebouxiophyceae and was significantly clustered with M.incisa SAG 2007,Lobosphaera tirolensis,M.bisecta,and Parietochloris incisa,but was clearly distant from P.pseudoalveolaris and P.alveolar.Transmission electron microscopy revealed pyrenoids traversed by many parallel thylakoids membranes,while starch grains were only clearly observed when cells were grown under nitrogen stress.Based on combined investigation of the phylogeny and morphologicalcDNA library of Myrmecia incisa H4301 was constructed using 2 phage vectors. The library consisted of 1.5x106 clones with a recombination rate of 90%, and 1942 clones were randomly sequenced. All 1854 readable expressed sequence tags （ESTs） were clustered into 596 non-redundant sequences （NRSs）, among which 126 NRSs were from 1384 ESTs, showing a high redundancy. Among the 596 NRSs, 30 were ribosomal RNA, and 152 significantly matched with those available in NCBI database and JGI Genome Portal, the latter were divided into nine subcategories. Overall, 59 NRSs were involved in photosynthesis, the respiratory electron transport chain, ATP synthesis, oxidation reduction, fatty acid biosynthesis, glucose metabolism, protein metabolism, and small molecular metabolism, suggesting that these genes were abundantly transcribed during energy and substance metabolism. Acyl-carrier protein, ferrodoxin and fatty acid elongase genes obtained from this cDNA library enabled presumption of a possible biosynthesis pathway of ArA in M. incisa. Codon usage analysis showed that the average G＋C content level of the total codons of 142 NRSs with 17798 codons in the predicted coding regions was 55.39%, and that of the third position in base trimers was 66.42%, indicating a strong bias toward cytosine and/or guanosine in this algal genome. Among all synonymous codons, NAG was most favored, while NUA was most avoided. Phylogenic trees inferred from ribulose-l,5-bisphosphate carboxylase/oxygenase small subunit genes and the extra partial sequences of 18S rRNA obtained from this library demonstrated that M. incisa belonged to Trebouxiophyceae and was significantly clustered with M. incisa SAG 2007, Lobosphaera tirolensis, M. bisecta, and Parietochloris incisa, but was clearly distant from P. pseudoalveolaris and P. alveolar. Transmission electron microscopy revealed pyrenoids traversed by many parallel thylakoids membranes, while starch grains were only clearly observed when cells were grown under nitrogen stress. Based on combine

关 键 词：表达序列标签 生物合成途径 脂肪酸合成 栗属 分类地位 微藻 cDNA文库 密码子使用 

分 类 号：Q943.2[生物学—植物学]