2015年9月11日訊 /生物谷BIOON/ --一個來自哈佛大學的研究小組近日在國際學術期刊PNAS上發表文章,他們利用延時拍攝的受激拉曼散射顯微鏡技術觀察到了體內細胞分裂過程中DNA的動態變化,並且這種技術不需要對DNA進行螢光標記。
為了深入了解癌症等疾病發生過程中細胞內各種生物過程所發生的變化,就需要在不幹擾細胞生命活動的情況下對細胞內部進行細緻觀察。通常情況下,如果想要對染色體活動進行觀察就需要對DNA進行標記,而這種方法具有侵入性可能會改變細胞內的一些天然微環境。
受激拉曼散射顯微技術是一種可以觀察到化學鍵振動頻率的成像技術,基於所處的分子環境,不同類型的化學鍵有不同的振動頻率。與傳統的拉曼光譜技術不同,受激拉曼散射顯微技術能夠在體內研究中實時地從樣品上快速獲得數據。利用這種技術,研究人員可以對細胞內DNA,蛋白質以及脂質的豐度和分布進行定位,使得他們可以通過無標記的方式對細胞分裂過程進行觀察。
研究人員首先在Hela細胞中觀察到了有絲分裂的不同時期,並對DNA,蛋白質以及脂質在細胞內的分布進行了三維重建。隨後他們又對促細胞分裂化學劑TPA處理小鼠的皮膚進行了觀察,看到了細胞周期的每一個階段,除此之外,研究人員還利用人類癌細胞處理免疫缺陷小鼠誘導其產生腫瘤,並對癌細胞的染色體運動進行了觀察。
這項研究表明無標記受激拉曼散射顯微技術可以在自然背景下對細胞內生物過程進行觀察,並為追蹤細胞行為提供了一種全新的方法,對於癌症等疾病的細胞學研究具有一定意義。(生物谷Bioon.com)
Label-free DNA imaging in vivo with stimulated Raman scattering microscopy
Fa-Ke Lua,1, Srinjan Basub,1,2, Vivien Igrasc, Mai P. Hoangd, Minbiao Jia, Dan Fua, Gary R. Holtoma, Victor A. Neele, Christian W. Freudigera,3, David E. Fisherc,4, and X. Sunney Xie
Label-free DNA imaging is highly desirable in biology and medicine to perform live imaging without affecting cell function and to obtain instant histological tissue examination during surgical procedures. Here we show a label-free DNA imaging method with stimulated Raman scattering (SRS) microscopy for visualization of the cell nuclei in live animals and intact fresh human tissues with subcellular resolution. Relying on the distinct Raman spectral features of the carbon-hydrogen bonds in DNA, the distribution of DNA is retrieved from the strong background of proteins and lipids by linear decomposition of SRS images at three optimally selected Raman shifts. Based on changes on DNA condensation in the nucleus, we were able to capture chromosome dynamics during cell division both in vitro and in vivo. We tracked mouse skin cell proliferation, induced by drug treatment, through in vivo counting of the mitotic rate. Furthermore, we demonstrated a label-free histology method for human skin cancer diagnosis that provides comparable results to other conventional tissue staining methods such as H&E. Our approach exhibits higher sensitivity than SRS imaging of DNA in the fingerprint spectral region. Compared with spontaneous Raman imaging of DNA, our approach is three orders of magnitude faster, allowing both chromatin dynamic studies and label-free optical histology in real time.