In vivo visualization of butterfly scale cell morphogenesis in Vanessa cardui

Abstract

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.

Hierarchical morphogenesis of swallowtail butterfly wing scale nanostructures

“…However, both the periodic stripes (microribs) and quasi-periodic spots (crossribs) are reminiscent of Turing patterns ( Meinhardt, 1982 ; Turing, 1952 ), that is, implying that an activator-inhibitor type mechanism could be involved in their formation. Alternatively, the crossrib pattern could be produced as a result of spontaneous processes like Ostwald ripening, phase separation, and/or biomechanical forces determined by the mechanical properties of the membranes, leading to stable, quasi-periodic, foam-like perforations on the plasma membrane in between ridges ( Dinwiddie et al, 2014 ; Elson et al, 2010 ; McDougal et al, 2021 ; Rosetti et al, 2017 ; Voorhees, 1985 ; Wilts et al, 2019 ).…”

“…Building on the classic studies on cellular organization of lepidopteran scales ( Ghiradella, 1974 ; Ghiradella, 1985 ; Ghiradella, 1989 ; Ghiradella and Radigan, 1976 ; Overton, 1966 ), a few recent studies utilized advances in microscopy techniques to interrogate the formation of longitudinal ridges ( Day et al, 2019 ; Dinwiddie et al, 2014 ; McDougal et al, 2021 ). These insights are, however, limited to ridge formation on the scale surface.…”

Live Detection of Intracellular Chitin in Butterfly Wing Epithelial Cells In Vivo Using Fluorescent Brightener 28: Implications for the Development of Scales and Color Patterns

“…In other words, FB28 staining may be useful for monitoring growing scales from the very beginning of their growth. It should be noted that intracellular chitin production patterns may influence scale nanostructures for structural colors [ 34 , 35 , 36 , 37 , 38 ] and that scale growth real-time imaging may be fruitful in biological and materials sciences [ 74 ].…”

The Modernity of Ancient Pigments: A Historical Approach

“…Isaac Newton (1643-1727) came to a similar conclusion: that the feathers' colors were due to "thin plates" in their structure [185]. Although Hooke's peacock was not available, the painted lady butterfly (Figure 25) is an excellent substitute to illustrate his observations [186]. Daguerre was the quintessential experimentalist but had no idea of the theoretical basis of his results.…”