作者：Aydogan Ozcan 来源：PNAS 发布时间：2012-9-20 10:59:554 w0 \- r8 @8 O4 }/ h9 k
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据每日科学网9月17日报道，美国加州大学洛杉矶分校的研究人员开发出一种新方式，能够利用相干光源和全息显微技术，同时观察和追踪上千个快速移动的精子，并精确记录下它们的三维运动轨迹。相关研究报告发表在当日的美国《国家科学院院刊》在线版上。
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9 ] h# ?3 R& v研究人员称，他们史无前例地追踪了2.4万个快速移动的细胞的路径，每个细胞的记录时间长达20秒。此次研究的主导者、该校电气工程和生物工程系教授埃道甘·奥兹坎说：“我们能精确追踪这些运动对象。每次能平行追踪上千个细胞的轨迹，并保持亚微米的精确度，以便了解数千个物体如何以不同的方式移动，同时揭示此前未知的细胞统计路径。”) y$ U0 i6 a+ U0 w
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奥兹坎及其同事利用了两个相干光源：波长为625纳米的红色LED（发光二极管）光源和波长为470纳米的蓝色LED光源，同时从两个不同角度照亮显微镜的视场。但他们并未使用传统的显微镜镜头进行观察，而是将感光芯片放置在透明的样本下。芯片会记录因上述光源生成的全息图，而软件算法则会基于获得的全息信息精确地显示显微镜下目标细胞的运动路径。
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众所周知，精子活动很难会被镜头捕捉到。而研究人员在约为17平方毫米的视场内，同时追踪了1500多个人类精子的三维轨迹，耗时不过数秒钟。他们发现，精子细胞会沿不断变化的迂回路径旅行，偶尔还会呈螺旋轨迹前行，而在90%的时间内，它们都会沿顺时针方向运动。科学家表示，如若没有新型的高通量显微技术，他们就不可能观察到罕见的“螺旋行进”现象，其只会发生在给定样本内4%至5%的细胞上。
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此外，这种基于透明材料运行的全息显微技术还能加快新药的研发速度，对于监控微生物疾病的药物治疗以及精子活动也十分重要。而科学家或许也可利用同样方法研究快速移动的细菌或其他浮游微生物，例如，新的全息成像技术有望披露更多未知的原生动物行为，并实时测试相关的药物疗法，以打击这些微生物最致命的种类或形式。（来源：科技日报 张巍巍）
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High-throughput lensfree 3D tracking of human sperms reveals rare statistics of helical trajectories+ Author Affiliations - aElectrical Engineering Department, University of California, Los Angeles, CA 90095;
- bBioengineering Department, University of California, Los Angeles, CA 90095;
- cDepartment of Information Physics and Engineering, Nanjing University of Science and Technology, Nanjing, Jiangsu 210094, China;
- dCalifornia NanoSystems Institute, University of California, Los Angeles, CA 90095; and
- eDepartment of Surgery, David Geffen School of Medicine, University of California, Los Angeles, CA 90095
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Edited by Wallace F. Marshall, UCSF, San Francisco, CA, and accepted by the Editorial Board August 16, 2012 (received for review July 21, 2012)
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AbstractDynamic tracking of human sperms across a large volume is a challenging task. To provide a high-throughput solution to this important need, here we describe a lensfree on-chip imaging technique that can track the three-dimensional (3D) trajectories of > 1,500 individual human sperms within an observation volume of approximately 8–17 mm3. This computational imaging platform relies on holographic lensfree shadows of sperms that are simultaneously acquired at two different wavelengths, emanating from two partially-coherent sources that are placed at 45° with respect to each other. This multiangle and multicolor illumination scheme permits us to dynamically track the 3D motion of human sperms across a field-of-view of > 17 mm2 and depth-of-field of approximately 0.5–1 mm with submicron positioning accuracy. The large statistics provided by this lensfree imaging platform revealed that only approximately 4–5% of the motile human sperms swim along well-defined helices and that this percentage can be significantly suppressed under seminal plasma. Furthermore, among these observed helical human sperms, a significant majority (approximately 90%) preferred right-handed helices over left-handed ones, with a helix radius of approximately 0.5–3 μm, a helical rotation speed of approximately 3–20 rotations/s and a linear speed of approximately 20–100 μm/s. This high-throughput 3D imaging platform could in general be quite valuable for observing the statistical swimming patterns of various other microorganisms, leading to new insights in their 3D motion and the underlying biophysics. http://www.pnas.org/content/early/2012/09/10/1212506109.abstract
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发表于 2012-9-19 15:58
发表于 2012-9-19 20:36
