近日,，國際著名雜志PLoS One在線刊登了巴西研究人員的最新研究成果“Trypanosoma cruzi Gene Expression in Response to Gamma Radiation，”,，文章中,，作者通過研究揭示了克魯斯錐蟲面對電離輻射有害壓力時(shí)如何來改變自身的基因表達(dá),，從而來應(yīng)對這種有害壓力。
克魯斯錐蟲是一種引起美洲錐蟲病的病原體,，這種病原體對電離輻射導(dǎo)致的DNA損傷有高度抗性,，一種可能性是，接受500Gy單位的γ射線輻射后,，這種病原體能夠啟動(dòng)自身的DNA雙鏈修復(fù)程序?qū)嗔袲NA進(jìn)行修復(fù),，48小時(shí)之內(nèi)便可以使染色體鏈得到修復(fù)?？茖W(xué)家曾經(jīng)將時(shí)程研究應(yīng)用于酵母,、擬南芥、古細(xì)菌,、人類成纖維細(xì)細(xì)胞以及耐輻射球菌中,，研究它們應(yīng)對γ射線時(shí)總體基因的表達(dá),，可是對于克魯斯錐蟲應(yīng)對電離輻射卻研究的比較少，尤其是在面對γ射線輻射時(shí),，克魯斯錐蟲進(jìn)行DNA修復(fù)和細(xì)胞恢復(fù)時(shí)基因表達(dá)的變化上研究的比較少,。
文章中，Priscila Grynberg等運(yùn)用時(shí)程微點(diǎn)陣分析的方法,，對于輻射后的克魯斯錐蟲標(biāo)出了273個(gè)基因表達(dá)發(fā)生明顯變化的基因,，這些表達(dá)發(fā)生變化的基因可以分為四類：編碼未知功能蛋白的基因；編碼假設(shè)蛋白的基因,；編碼retrotransposon hot spot（RHS）的基因以及一些無用的序列,，60%以上的基因都是編碼未知功能蛋白的上調(diào)基因，其余的上調(diào)基因包括RHS和無用的一些序列,，作者的研究揭示克魯斯錐蟲基因的轉(zhuǎn)錄并不是依靠操縱子單位，而是依靠多順反子單位來進(jìn)行轉(zhuǎn)錄,，在作者的研究中,，他們發(fā)現(xiàn)了一個(gè)DNA雙鏈破碎修復(fù)過程的基因，該基因也是上調(diào)的,，編碼酪胺?；?DNA磷酸二酯酶，這篇文章,，作者闡釋了克魯斯錐蟲在應(yīng)對電路輻射時(shí)的特殊應(yīng)對機(jī)制,，從而為后期的科學(xué)研究中提出了很多有意思的問題，在面對危害壓力時(shí),，有機(jī)體如何改變自身的基因表達(dá)來躲避這種危害,。（生物谷：T.Shen編譯）
doi:10.1371/journal.pone.0029596
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Trypanosoma cruzi Gene Expression in Response to Gamma Radiation
Priscila Grynberg1, Danielle Gomes Passos-Silva1, Marina de Moraes Mourão3,5, Roberto Hirata Jr4, Andrea Mara Macedo1, Carlos Renato Machado1, Daniella Castanheira Bartholomeu2, Glória Regina Franco1*
Trypanosoma cruzi is an organism highly resistant to ionizing radiation. Following a dose of 500 Gy of gamma radiation, the fragmented genomic DNA is gradually reconstructed and the pattern of chromosomal bands is restored in less than 48 hours. Cell growth arrests after irradiation but, while DNA is completely fragmented, RNA maintains its integrity. In this work we compared the transcriptional profiles of irradiated and non-irradiated epimastigotes at different time points after irradiation using microarray. In total, 273 genes were differentially expressed; from these, 160 were up-regulated and 113 down-regulated. We found that genes with predicted functions are the most prevalent in the down-regulated gene category. Translation and protein metabolic processes, as well as generation of precursor of metabolites and energy pathways were affected. In contrast, the up-regulated category was mainly composed of obsolete sequences (which included some genes of the kinetoplast DNA), genes coding for hypothetical proteins, and Retrotransposon Hot Spot genes. Finally, the tyrosyl-DNA phosphodiesterase 1, a gene involved in double-strand DNA break repair process, was up-regulated. Our study demonstrated the peculiar response to ionizing radiation, raising questions about how this organism changes its gene expression to manage such a harmful stress.
