Psilodimitrakopoulos Sotiris, Santos Susana I C O, Amat-Roldan Ivan, Thayil Anisha K N, Artigas David, Loza-Alvarez Pablo
ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels, Barcelona, Spain.
J Biomed Opt. 2009 Jan-Feb;14(1):014001. doi: 10.1117/1.3059627.
The polarization dependence of second harmonic generation (SHG) microscopy is used to uncover structural information in different muscle cells in a living Caenorhabditis elegans (C. elegans) nematode. This is done by using a generalized biophysical model in which element ratios for the associated second-order nonlinear tensor and angular orientations for thick filaments are retrieved using a pixel-by-pixel fitting algorithm. As a result, multiple arbitrary orientations of thick filaments, at the pixel-resolution level, are revealed in the same image. The validity of our method is first corroborated in well-organized thick filaments such as the nonfibrilar body wall muscles. Next, a region of the nonstriated muscular cells of the pharynx is analyzed by showing different regions with homogenous orientations of thick filament as well as their radial distribution. As a result, different sets of the nonstriated muscle cell groups in the pharynx of this nematode were exposed. This methodology is presented as a filtering mechanism to uncover biological information unreachable by common intensity SHG microscopy. Finally, a method to experimentally retrieve the distribution of the effective orientation of active SHG molecules is proposed and tested.
二次谐波产生（SHG）显微镜的偏振依赖性被用于揭示活的秀丽隐杆线虫（C. elegans）中不同肌肉细胞的结构信息。这是通过使用一个广义生物物理模型来实现的，在该模型中，使用逐像素拟合算法检索相关二阶非线性张量的元素比率和粗肌丝的角取向。结果，在同一图像中揭示了粗肌丝在像素分辨率水平上的多个任意取向。我们方法的有效性首先在组织良好的粗肌丝（如非纤维状体壁肌肉）中得到证实。接下来，通过展示具有均匀粗肌丝取向及其径向分布的不同区域，对咽部的非横纹肌细胞区域进行了分析。结果，该线虫咽部不同组别的非横纹肌细胞群被揭示出来。这种方法被作为一种过滤机制提出，以揭示普通强度SHG显微镜无法获取的生物信息。最后，提出并测试了一种通过实验检索活性SHG分子有效取向分布的方法。
