Fig. 11

Correlative light and electron microscopy analysis of microtubules in untransfected CvDCX1-expressing Xenopus cells. a EM images of microtubules in sections of an untransfected Xenopus cell. In all cases where they are countable, 13 protofilaments (pf) are present. No microtubules with other than 13 pf were seen in untransfected cells. b Fluorescence and DIC light microscope images of the cell sectioned in a. The cell is from a line expressing EGFP-α-tubulin. The plane of sectioning in the EM images is shown by the white bar. c EM images of microtubules in sections of a Xenopus cell transfected with mCherryFP-CvDCX1. All microtubules have 13 pf. The tannic-acid-enhancement of microtubule staining (see Methods) is more effective when the microtubules are heavily decorated, which makes the protofilaments more obvious and more easily countable, but the diameter of the microtubules is approximately the same as in untransfected cells. d Fluorescence and DIC light microscopy images of the cell sectioned in c. mCherryFP-CvDCX1 is shown in red, EGFP-α-tubulin in green. The plane of section is shown by the white bar. The magnification is the same as for b. Note that the elongated narrow extension of the transfected cell lies on top of another untransfected cell, running over the edge of the latter’s nucleus. e Low magnification EM images of a cross-section of the cell shown in d. The thin extension of the transfected cell is seen crossing over the underlying untransfected cell. The region within the white box, shown enlarged on the right, contains > 100 parallel microtubules viewed in cross-section, appearing as tiny black doughnuts at this magnification