Optical Diffraction and Translational Reinforcement of Microtubules Having a Prominent Helical Wall Structure

Optical diffraction patterns obtained from electron micrograph images showing crystalline or repeating units can provide confirmatory and even new information regarding substructure (7, 10, 11) . Essentially, an image of a portion of an electron micrograph is used as a two-dimensional grating to produce a diffraction pattern . This pattern of spots can indicate major and minor periodicities within the subject, as well as provide the basis for measurements of subunit spacing . Although an optical bench with a laser as a coherent light source is required to obtain maximum information (11), some information can be obtained with a minimum investment by using the light microscope as a diffractometer (7) . Also, information on radial and linear periodicity can be obtained by photographic means through incremental rotation or translation (6, 12, 13) . In this method, an enlarged image of the specimen being tested is commonly projected on photographic printing paper, which is then rotated or translated through a series of predetermined increments. Reinforcement is obtained when the chosen increments correspond to a repeat pattern in the image . In the present study, images of negatively stained cytoplasmic microtubules from frog lungfluke (Haematoloechus medioplexus) sperm were subjected to optical diffraction and translational reinforcement . Microtubules of fluke sperm are well suited for such studies, for they are relatively stable, easily negatively stained, and have repeating transverse striations which apparently reflect an underlying helical pattern (2-4) . Information obtained in this study is correlated with previous measurements and observations by the author, and a model is discussed which satisfies the available data .