近日，英国医学研究理事会的科学家使用一种光学投影层析成像技术，首次获得果蝇内部结构的3D图像，这有利于加速对老年痴呆症和影响人类脑细胞的其他疾病的基因学研究。
在9月份的《公共科学图书馆·综合》（PLoS ONE）杂志上，该研究小组描述了他们如何利用光学投影层析成像技术获得成熟果蝇脑内部图像，并对其大脑退化情况进行研究。医学研究理事会的博士生李安内·穆葛解释说：“果蝇外骨骼颜色较暗，所以无法使用标准光学显微镜从里面观察。这意味着过去研究者必须解剖其组织获得信息。现在我们通过漂白其骨骼解决了这个问题，当果蝇变成无色时，利用成像技术不仅可以观察内部器官还可以生成整个果蝇的二维和三维图片。”
领导该研究的医学研究理事会人类基因学研究部的玛丽说：“在阿尔茨海默病、帕金森和运动神经原疾病中会发生神经退行性病变，也就是脑细胞功能会慢慢退化，但这种病变并不仅仅存在于人类也发生在昆虫中。如秋季蜜蜂和黄蜂在死亡前通常会有很多怪异行为。”
果蝇和人类有很多基因的功能类似，因此常被用来研究基因如何影响人类疾病，但由于其头部和大脑非常脆弱而给研究带来障碍。光学投影层析能帮助研究者不用解剖就能观察果蝇大脑如何随特定基因活动而变化，还能了解不同基因的表达形式，从而有助于确认控制中枢神经系统的基因，为人类大脑研究提供重要参考信息。（科技日报）
原始出处:
PLoS ONE
Received: June 15, 2007; Accepted: August 8, 2007; Published: September 5, 2007
Three-Dimensional Imaging of Drosophila melanogaster
Leeanne McGurk1, Harris Morrison1, Liam P. Keegan1, James Sharpe2, Mary A. O'Connell1*
1 Medical Research Council Human Genetics Unit, Edinburgh, United Kingdom, 2 Systems Biology Program, Centre de Regulació Genòmica, Barcelona, Spain
Background
The major hindrance to imaging the intact adult Drosophila is that the dark exoskeleton makes it impossible to image through the cuticle. We have overcome this obstacle and describe a method whereby the internal organs of adult Drosophila can be imaged in 3D by bleaching and clearing the adult and then imaging using a technique called optical projection tomography (OPT). The data is displayed as 2D optical sections and also in 3D to provide detail on the shape and structure of the adult anatomy.
Methodology
We have used OPT to visualize in 2D and 3D the detailed internal anatomy of the intact adult Drosophila. In addition this clearing method used for OPT was tested for imaging with confocal microscopy. Using OPT we have visualized the size and shape of neurodegenerative vacuoles from within the head capsule of flies that suffer from age-related neurodegeneration due to a lack of ADAR mediated RNA-editing. In addition we have visualized tau-lacZ expression in 2D and 3D. This shows that the wholemount adult can be stained without any manipulation and that this stain penetrates well as we have mapped the localization pattern with respect to the internal anatomy.
Conclusion
We show for the first time that the intact adult Drosophila2 can be imaged in 3D using OPT, also we show that this method of clearing is also suitable for confocal microscopy to image the brain from within the intact head. The major advantage of this is that organs can be represented in 3D in their natural surroundings. Furthermore optical sections are generated in each of the three planes and are not prone to the technical limitations that are associated with manual sectioning. OPT can be used to dissect mutant phenotypes and to globally map gene expression in both 2D and 3D.
Figure 2. The data output.
The data from the scans are reconstructed in 3D, the two datasets, brightfield (red, exoskeleton) and fluorescent (green, anatomy), are superimposed, and the information is displayed in all three planes (A–D). Single heads can be imaged (E). The data can also be displayed and explored in 3D (F, G).
