Resources / Publications
Anthony D. McDougal (1), Sungsam Kang (2), Zahid Yaqoob (2) , Peter T. C. So (1,2,3), Mathias Kolle (1)
Proceedings of the National Academy of Sciences, 118, Issue 49, December 2021. DOI: 10.1073/pnas.2112009118
metamorphosis; butterfly scales; biological structure formation; in vivo quantitative phase; imaging; cuticle secretion
During metamorphosis, the wings of a butterfly sprout hundreds of thousands of scales with intricate microstructures and nano-structures that determine the wings’ optical appearance, wetting characteristics, thermodynamic properties, and aerodynamic behavior. Although the functional characteristics of scales are well known and prove desirable in various applications, the dynamic processes and temporal coordination required to sculpt the scales’ many structural features remain poorly understood. Current knowledge of scale growth is primarily gained from ex vivo studies of fixed scale cells at discrete time points; to fully understand scale formation, it is critical to characterize the time-dependent morphological changes throughout their development. Here, we report the continuous, in vivo, label-free imaging of growing scale cells of Vanessa cardui using speckle-correlation reflection phase microscopy. By capturing time-resolved volumetric tissue data together with nanoscale surface height information, we establish a morphological timeline of wing scale formation and gain quantitative insights into the underlying processes involved in scale cell patterning and growth. We identify early differences in the patterning of cover and ground scales on the young wing and quantify geometrical parameters of growing scale features, which suggest that surface growth is critical to structure formation. Our quantitative, time-resolved in vivo imaging of butterfly scale development provides the foundation for decoding the processes and biomechanical principles involved in the formation of functional structures in biological materials.
Dragonfly was used to measure length, width, and thickness of cover scales in deconvolved 3D amplitude data. It was also used to define the ROI of butterfly scales.
(1)Department of Mechanical Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139.
(2)Laser Biomedical Research Center, G. R. Harrison Spectroscopy Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139.
(3)Department of Biological Engineering, Massachusetts Institute of Technology, Cambridge, MA 02139.
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