IMAGING INTACT MYOFIBRILS WITH A NEAR-FIELD SCANNING OPTICAL MICROSCOPE

Fluorescently labelled myofibrils were imaged in physiological salt so lution by near-field scanning optical microscopy and shear-force micro scopy. These myofibrils were imaged in vitro, naturally adhering to gl ass while retaining their ability to contract. The Z-line protein stru cture of the myofibrils was antibody labelled and easily identified in the near-field fluorescence images. The distinctive protein banding s tructure of the myofibril was also seen clearly in the shear-force ima ges without any labelling requirement. With the microscope in the tran smission mode, resolution of the fluorescence images was degraded sign ificantly by excessive specimen thickness (>1 mu m), whereas the shear -force images were less affected by specimen thickness and more affect ed by poor adherence to the substrate, Although the exact mechanism ge nerating contrast in the shear-force images is still unknown, shear-fo rce imaging appears to be a promising new imaging modality.