Publications by authors named "Haruhiko Adachi"

5 Publications

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Epithelial folding determines the final shape of beetle horns.

Curr Opin Genet Dev 2021 Apr 10;69:122-128. Epub 2021 Apr 10.

Department of Entomology, Washington State University, Pullman, WA, 99163 USA. Electronic address:

The elaborate ornaments and weapons of sexual selection, such as the vast array of horns observed in scarab beetles, are some of the most striking outcomes of evolution. How these novel traits have arisen, develop, and respond to condition is governed by a complex suite of interactions that require coordination between the environment, whole-animal signals, cell-cell signals, and within-cell signals. Endocrine factors, developmental patterning genes, and sex-specific gene expression have been shown to regulate beetle horn size, shape, and location, yet no overarching mechanism of horn shape has been described. Recent advances in microscopy and computational analyses combined with a functional genetic approach have revealed that patterning genes combined with intricate epithelial folding and movement are responsible for the final shape of a beetle head horn.
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http://dx.doi.org/10.1016/j.gde.2021.03.003DOI Listing
April 2021

Computational analyses decipher the primordial folding coding the 3D structure of the beetle horn.

Sci Rep 2021 Jan 13;11(1):1017. Epub 2021 Jan 13.

Pattern Formation Laboratory, Graduate School of Frontier Biosciences, Osaka University, Suita, Osaka, 565-0871, Japan.

The beetle horn primordium is a complex and compactly folded epithelial sheet located beneath the larval cuticle. Only by unfolding the primordium can the complete 3D shape of the horn appear, suggesting that the morphology of beetle horns is encoded in the primordial folding pattern. To decipher the folding pattern, we developed a method to manipulate the primordial local folding on a computer and clarified the contribution of the folding of each primordium region to transformation. We found that the three major morphological changes (branching of distal tips, proximodistal elongation, and angular change) were caused by the folding of different regions, and that the folding mechanism also differs according to the region. The computational methods we used are applicable to the morphological study of other exoskeletal animals.
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http://dx.doi.org/10.1038/s41598-020-79757-2DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7806817PMC
January 2021

Genetical control of 2D pattern and depth of the primordial furrow that prefigures 3D shape of the rhinoceros beetle horn.

Sci Rep 2020 10 29;10(1):18687. Epub 2020 Oct 29.

Ecological Genetics Laboratory, Department of Genomics and Evolutionary Biology, National Institute of Genetics, Mishima, Shizuoka, 411-8540, Japan.

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.
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http://dx.doi.org/10.1038/s41598-020-75709-yDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7596553PMC
October 2020

Structure and development of the complex helmet of treehoppers (Insecta: Hemiptera: Membracidae).

Zoological Lett 2020 24;6. Epub 2020 Feb 24.

4Faculty of Environmental Earth Sciences, Hokkaido University, Sapporo, Hokkaido Japan.

Some insects possess complex three-dimensional (3D) structures that develop under the old cuticle prior to the last imaginal molt. Adult treehoppers (Insecta: Hemiptera: Auchenorrhyncha: Membracidae) have one such complex 3D structure, known as a helmet, on their dorsal side. The adult helmet likely forms inside the nymphal pronotum during the final instar nymphal stage. Previous morphological studies have reported that the adult helmet is a large, bi-layered, plywood-like structure, whereas the nymphal pronotum is a monolayer, sheath-like structure. The adult helmet is much larger than nymphal helmet. Thus, the emergence of the adult helmet involves two structural transitions: a transition from a monolayer, sheath-like pronotum to a bi-layer, plywood-like helmet, and a transition in size from small to large. However, when, how, and in what order these transitions occur within the nymphal cuticle is largely unknown. To determine how adult helmet development occurs under the nymphal cuticle, in the present study we describe the morphology of the final adult helmet and investigate developmental trajectories of the helmet during the final instar nymphal stage. We used micro-CT, scanning electron microscope and paraffin sections for morphological observations, and used as a model species. We found that the structural transition (from monolayer, sheath-like structure to bi-layer, roof-like structure) occurs through the formation of a "miniature" of the adult helmet during the middle stage of development and that subsequently, extensive folding and furrows form, which account for the increase in size. We suggest that the making of a "miniature" is the key developmental step for the formation of various 3D structures of treehopper helmets.
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http://dx.doi.org/10.1186/s40851-020-00155-7DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7041272PMC
February 2020

Anisotropy of cell division and epithelial sheet bending via apical constriction shape the complex folding pattern of beetle horn primordia.

Mech Dev 2018 08 18;152:32-37. Epub 2018 Jun 18.

Graduate School of Bioagricultural Sciences, Nagoya University, Nagoya, Aichi 464-8601, Japan; Faculty of Environmental Earth Sciences, Hokkaido University, Sapporo, Hokkaido 060-0810, Japan. Electronic address:

Insects can dramatically change their outer morphology at molting. To prepare for this drastic transformation, insects generate new external organs as folded primordia under the old cuticle. At molting, these folded primordia are physically extended to form their final outer shape in a very short time. Beetle horns are a typical example. Horn primordia are derived from a flat head epithelial sheet, on which deep furrows are densely added to construct the complex folded structure. Because the 3D structure of the pupa horn is coded in the complex furrow pattern, it is indispensable to know how and where the furrows are set. Here, we studied the mechanism of furrow formation using dachsous (ds) gene knocked down beetles that have shorter and fatter adult horns. The global shape of the beetle horn primordia is mushroom like, with dense local furrows across its surface. Knockdown of ds by RNAi changed the global shape of the primordia, causing the stalk region become apparently thicker. The direction of cell division is biased in wildtype horns to make the stalk shape thin and tall. However, in ds knocked down beetles, it became random, resulting in the short and thick stalk shape. On the other hand, a fine and dense local furrow was not significantly affected by the ds knockdown. In developing wildtype horn primordia, we observed that, before the local furrow is formed, the apical constriction signal emerged at the position of the future furrow, suggesting the pre-pattern for the fine furrow pattern. According to the results, we propose that development of complex horn primordia can be roughly divided to two distinct processes, 1) development of global primordia shape by anisotropic cell division, and 2) local furrow formation via actin-myosin dependent apical constriction of specific cells.
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http://dx.doi.org/10.1016/j.mod.2018.06.003DOI Listing
August 2018