Left–right asymmetry in the microstructure of the hindwings of European hornet revealed by scanning electron microscopy and microscopic vibrational circular dichroism

Abstract

Observation of hornet hindwings using scanning electron microscopy revealed a coating composed of helically wound hairs of approximately 10 μm in diameter and 100 μm in length. A strict enantiomeric relationship in the organ morphology existed in the area closest to the leading edge of the wings: the hairs on the right wing exhibited left-handedness, whereas those on the left wing exhibited right-handedness. Evaluation of microscopic vibration circular dichroism spectra indicated that both sides of the wings comprised β-sheets. However, a notable difference in VCD spectral shapes existed between the left and right wings (VCD_left and VCD_right, respectively), although their IR spectra were nearly identical. From the spectral shape of the difference (VCD_left − VCD_right), one possibility is proposed that the handedness in the hairs on the left and right hindwings is related to the opposite chirality of the protein structure. The correlation between organ-level enantiomeric relationships and the protein secondary structure observed here is a novel observation that requires further investigation to obtain deeper insights.