X-ray diffraction recording from single axonemes of eukaryotic flagella

Nishiura, Masaya*; Toba, Shiori*; Takao, Daisuke*; Miyashiro, Daisuke*; Sakakibara, Hitoshi*; Matsuo, Tatsuhito; Kamimura, Shinji*; Oiwa, Kazuhiro*; Yagi, Naoto*; Iwamoto, Hiroyuki*

We report the first X-ray diffraction patterns recorded from single axonemes of eukaryotic flagella with a diameter of only 0.2 m, by using the technique of cryomicrodiffraction. A spermatozoon isolated from Drosophila melanogaster, was mounted straight in a glass capillary, quickly frozen and its 800-m segment was irradiated end-on with intense synchrotron radiation X-ray microbeams (diameter, 2 m) at 74 K. Well-defined diffraction patterns were recorded, consisting of a large number of isolated reflection spots. The patterns had features of an 18-fold rotational symmetry as expected from the axonemal structure. The diffraction patterns were compared with the results of model calculations based on a published electron micrograph of the Drosophila axoneme. The comparison provided information on the native state of axoneme, including estimates of axonemal diameter and interdoublet spacing.