Walker, Andrew A.Weisman, SarahChurch, Jeffrey S.Merritt, David J.Mudie, Stephen T.Sutherland, Tara D.2015-11-242015-11-241932-6203http://hdl.handle.net/1885/16686Raspy crickets (Orthoptera: Gryllacrididae) are unique among the orthopterans in producing silk, which is used to build shelters. This work studied the material composition and the fabrication of cricket silk for the first time. We examined silk-webs produced in captivity, which comprised cylindrical fibers and flat films. Spectra obtained from micro-Raman experiments indicated that the silk is composed of protein, primarily in a beta-sheet conformation, and that fibers and films are almost identical in terms of amino acid composition and secondary structure. The primary sequences of four silk proteins were identified through a mass spectrometry/cDNA library approach. The most abundant silk protein was large in size (300 and 220 kDa variants), rich in alanine, glycine and serine, and contained repetitive sequence motifs; these are features which are shared with several known beta-sheet forming silk proteins. Convergent evolution at the molecular level contrasts with development by crickets of a novel mechanism for silk fabrication. After secretion of cricket silk proteins by the labial glands they are fabricated into mature silk by the labium-hypopharynx, which is modified to allow the controlled formation of either fibers or films. Protein folding into beta-sheet structure during silk fabrication is not driven by shear forces, as is reported for other silks.Dr. Walker was supported by a PhD scholarship from Australian National University. Additional funding by the Commonwealth Scientific and Industrial Research Organisation (CSIRO). Part of this research was undertaken at the SAXS/WAXS beamline at the Australian Synchrotron, Victoria, Australia. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.© 2012 Walker et al. This is an open-access article distributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.acinar cellsanimalsfibroinsgene librarygryllidaeinsect proteinsmass spectrometrymolecular structuresilkspectrum analysis, raman2012-02-1510.1371/journal.pone.00304082015-12-10