Genetical control of 2D pattern and depth of the primordial furrow that prefigures 3D shape of the rhinoceros beetle horn.
H Adachi, K Matsuda, T Niimi, S Kondo, H Gotoh
Scientific Reports 10, 18687 (2020) DOI:10.1038/s41598-020-75709-y
The head horn of the Asian rhinoceros beetle develops as an extensively folded primordium before unfurling into its final 3D shape at the pupal molt. The information of the final 3D structure of the beetle horn is prefigured in the folding pattern of the developing primordium. However, the developmental mechanism underlying epithelial folding of the primordium is unknown. In this study, we addressed this gap in our understanding of the developmental patterning of the 3D horn shape of beetles by focusing on the formation of furrows at the surface of the primordium that become the bifurcated 3D shape of the horn. By gene knockdown analysis via RNAi, we found that knockdown of the gene Notch disturbed overall horn primordial furrow depth without affecting the 2D furrow pattern. In contrast, knockdown of CyclinE altered 2D horn primordial furrow pattern without affecting furrow depth. Our results show how the depth and 2D pattern of primordial surface furrows are regulated at least partially independently during beetle horn development, and how both can alter the final 3D shape of the horn.
Source: H Adachi, et al., Scientific Reports 10, 18687 (2020) DOI:10.1038/s41598-020-75709-y
Figure: Summary of beetle horn development focusing on folding of horn primordia. The final 3D shape of horn has been already prefigured when the development of folding is done. In this study, we demonstrated that the development of primordia folding can be divided into (1) macro structure formation and (2) micro furrow formation. Micro furrow formation can be further divided into depth regulation and 2D pattern formation via Notch and CyclinE control, respectively.