FibrilJ: ImageJ plugin for fibrils’ diameter and persistence length determination

Application of microscopy to evaluate the morphology and size of filamentous proteins and amyloids requires new and creative approaches to simplify and automate the image processing. The estimation of mean values of fibrils diameter, length and bending stiffness on micrographs is a major challenge. For this purpose we developed an open-source FibrilJ plugin for the ImageJ/FiJi program. It automatically recognizes the fibrils on the surface of a mica, silicon, gold or formvar film and further analyzes them to calculate the distribution of fibrils by diameters, lengths and persistence lengths. The plugin has been validated by the processing of TEM images of fibrils formed by Sup35NM yeast protein and artificially created images of rod-shape objects with predefined parameters. Novel data obtained by SEM for Sup35NM protein fibrils immobilized on silicon and gold substrates are also presented and analyzed.

运用显微镜评估丝状蛋白和淀粉样物质的形态及尺寸，亟需采取新颖且富有创意的方法以简化并自动化图像处理流程。在显微镜图像上估算纤维直径、长度和弯曲刚度的平均值构成了一个重大的挑战。为此，我们为ImageJ/FiJi程序开发了一款开源的FibrilJ插件。该插件能够自动识别云母、硅、金或formvar薄膜表面的纤维，并进一步对其进行分析，以计算纤维的直径、长度和持久长度的分布。该插件已通过处理由Sup35NM酵母蛋白形成的纤维的透射电子显微镜（TEM）图像以及具有预定参数的棒状物体的人工图像进行验证。此外，还展示了利用扫描电子显微镜（SEM）获得的Sup35NM蛋白纤维在硅和金基底上固定的新型数据，并对其进行了分析。