10月27日,BMC evolutionary biology雜志在線發(fā)表了中國(guó)科學(xué)院水生生物研究所原生動(dòng)物功能基因組學(xué)學(xué)科組博士生熊杰完成的論文,。
該研究鑒定得到了165個(gè)四膜蟲(chóng)ATP結(jié)合盒轉(zhuǎn)運(yùn)蛋白基因,，是目前已報(bào)道的含該類基因最多的真核生物,；對(duì)這些基因進(jìn)行系統(tǒng)發(fā)育和保守內(nèi)含子分析,、以及與同為纖毛蟲(chóng)的草履蟲(chóng)進(jìn)行比較,，發(fā)現(xiàn)眾多的四膜蟲(chóng)ATP結(jié)合盒轉(zhuǎn)運(yùn)蛋白是在四膜蟲(chóng)與草履蟲(chóng)分化后通過(guò)基因復(fù)制擴(kuò)張產(chǎn)生的（約800 Mya）,；進(jìn)一步對(duì)它們的基因表達(dá)譜和表達(dá)進(jìn)化模式的分析表明,，部分四膜蟲(chóng)ATP結(jié)合盒轉(zhuǎn)運(yùn)蛋白基因在發(fā)生基因復(fù)制后其表達(dá)和功能也發(fā)生了分歧,，同時(shí)這些基因在基因組中保留下來(lái)的模式則更多地符合新功能化和劑量平衡的模型,。
此項(xiàng)研究是該學(xué)科組繼去年完成四膜蟲(chóng)細(xì)胞色素P450基因家族分子進(jìn)化工作（BMC genomics）之后，對(duì)四膜蟲(chóng)中與環(huán)境感知和響應(yīng)相關(guān)的多基因家族進(jìn)化模式和功能演化分析的新進(jìn)展,，進(jìn)一步驗(yàn)證了他們提出的四膜蟲(chóng)是研究該類多基因家族分子進(jìn)化良好真核生物的觀點(diǎn),。
該研究得到了國(guó)家自然科學(xué)基金項(xiàng)目和中科院知識(shí)創(chuàng)新重要方向性項(xiàng)目的資助。（生物谷Bioon.com）
生物谷推薦英文摘要：
BMC Evolutionary Biology 2010, 10:330doi:10.1186/1471-2148-10-330
Genome-wide identification and evolution of ATP-binding cassette transporters in the ciliate Tetrahymena thermophila: A case of functional divergence in a multigene family
Jie Xiong , Lifang Feng , Dongxia Yuan , Chengjie Fu and Wei Miao
Background
In eukaryotes, ABC transporters that utilize the energy of ATP hydrolysis to expel cellular substrates into the environment are responsible for most of the efflux from cells. Many members of the superfamily of ABC transporters have been linked with resistance to multiple drugs or toxins. Owing to their medical and toxicological importance, members of the ABC superfamily have been studied in several model organisms and warrant examination in newly sequenced genomes.
Results
A total of 165 ABC transporter genes, constituting a highly expanded superfamily relative to its size in other eukaryotes, were identified in the macronuclear genome of the ciliate Tetrahymena thermophila. Based on ortholog comparisons, phylogenetic topologies and intron characterizations, each highly expanded ABC transporter family of T. thermophila was classified into several distinct groups, and hypotheses about their evolutionary relationships are presented. A comprehensive microarray analysis revealed divergent expression patterns among the members of the ABC transporter superfamily during different states of physiology and development. Many of the relatively recently formed duplicate pairs within individual ABC transporter families exhibit significantly different expression patterns. Further analysis showed that multiple mechanisms have led to functional divergence that is responsible for the preservation of duplicated genes.
Conclusion
Gene duplications have resulted in an extensive expansion of the superfamily of ABC transporters in the Tetrahymena genome, making it the largest example of its kind reported in any organism to date. Multiple independent duplications and subsequent divergence contributed to the formation of different families of ABC transporter genes. Many of the members within a gene family exhibit different expression patterns. The combination of gene duplication followed by both sequence divergence and acquisition of new patterns of expression likely plays a role in the adaptation of Tetrahymena to its environment.
