Molecular Genetics and Genomics雜志6月發(fā)表了中科院北京基因組研究所基因組科學(xué)及信息重點實驗室與華東師范大學(xué)生命科學(xué)學(xué)院合作的研究成果Analysis and comparison of a set of expressed sequence tags of the parthenogenetic water flea Daphnia carinata,。
隆線溞隸屬節(jié)肢動物門(Arthropoda),、甲殼綱(Crustacea),、鰓足亞綱(Branchiopoda),、雙甲目(Diplostraca)、枝角亞目(Cladocera),、溞科,、溞屬 。隆線溞有兩種不同的生殖方式：孤雌生殖(單性生殖)與兩性生殖,。當(dāng)外界條件比較適宜時,，枝角類就行孤雌生殖。在環(huán)境條件惡化時,，枝角類就行兩性生殖,，這時種群中不僅有雌體，同時還出現(xiàn)雄體,，二者隨即交配,。兩種生殖方式的交替，是枝角類對外界環(huán)境的一種特殊適應(yīng),，孤雌生殖在有利環(huán)境下充分利用了條件,，而兩性生殖在不利環(huán)境下保證了種的生存與連續(xù)性。枝角類不但生殖方式特殊,，還是一類重要的水生經(jīng)濟(jì)動物,。它具有較高的蛋白質(zhì)含量(占干重的40%-60%),，還含有水產(chǎn)經(jīng)濟(jì)類動物魚,、蝦,、蟹等生長發(fā)育所必需的氨基酸、維生素及鈣質(zhì),，是生產(chǎn)上十分理想的活體餌料,，其產(chǎn)量與漁業(yè)生產(chǎn)關(guān)系密切。
科研人員對樣品隨機(jī)測序（5′端）3072條,，一共得到3,040條高質(zhì)量的EST序列,，并最終得到1,495條unique sequences（465條contigs和1,030條singletons）。通過與公共數(shù)據(jù)庫內(nèi)的序列進(jìn)行比對,，總共注釋了959個（64%）基因,。通過基因表達(dá)豐度和功能分析（主要是GO和KEGG），對其基因表達(dá)譜特征有了全面的認(rèn)識,。其中與生殖和胚胎發(fā)育相關(guān)的基因共鑒定到57個基因,，其中VTN和VTG基因所占比重較高；發(fā)現(xiàn)了生殖特異性表達(dá)的基因如ubulin alpha chain,；另外檢測到一些化學(xué)感應(yīng)基因（CSP）和熱激蛋白（HSP）基因,。推測這些密切感受環(huán)境變化的基因在孤雌生殖中起到重要的作用，為以后克隆其全長基因序列并研究功能奠定了基礎(chǔ),。
通過與近緣物種蚤狀溞（Daphnia pulex）基因組序列的比對,，比對之后得到1,283條（86%）unique sequences與其基因組有較高的相似性。其中1,158條比對到基因的編碼區(qū)域,，另外有125條序列比對到基因間區(qū)或者內(nèi)含子區(qū),。這些結(jié)果從側(cè)面反映了水溞近緣種間（D. pulex和D. carinata）基因組序列、表達(dá)水平上的差異,，為后續(xù)的比較基因組學(xué)分析提供了有力的支持,。（生物谷Bioon.com）
生物谷推薦原始出處：
Mol Genet Genomics. 2009 May 26
Analysis and comparison of a set of expressed sequence tags of the parthenogenetic water flea Daphnia carinata.
Xu X, Song S, Wang Q, Qin F, Liu K, Zhang X, Hu S, Zhao Y.
Department of Life Science, East China Normal University, 200062, Shanghai, People's Republic of China.
The water flea Daphnia carinata (D. carinata) reproduces both sexually and parthenogenetically, yet little is known about the genes involved in these processes. To further clarify the reproductive biology of Daphnia and elucidate their unique mechanism of reproductive transformation, we have generated and characterized an expressed sequence tag (EST) data set from D. carinata. A set of 1,495 clusters were generated from sequencing 3,072 randomly chosen clones from a parthenogenetic, juvenile water flea cDNA library. The nucleic acid and deduced amino acid sequences were compared with known GenBank sequences. Functional annotation found that 959 clusters showed significant homology with known genes involved in a broad range of activities, including metabolism, translation, development and reproduction, as well as genes involved in sensing environmental factors. We speculate that genes involved in development and reproduction, along with genes that allow the organism to sense changes in the environment, play important roles in the process of parthenogenetic reproduction and could be markers of the early steps of sexual differentiation. Additionally, 86% of the D. Carinata unique sequences could be stringently mapped to the D. pulex genome, of which 125 mapped to intergenic and intronic regions on the current assembly. Our results provide practical insight into crustacean reproductive biology, in addition to establishing a new animal model for reproductive and developmental biology.
