Presentation Information
[MS15-01]A three-dimensional vertex dynamics model for understanding the twisting phenomenon of the hindgut of Drosophila
*AKIYAMA Masakazu1, Takamichi Sushida4, Mikiko Inaki3, Kenji Matsuno2 (1. University of Toyama (Japan), 2. Osaka University (Japan), 3. University of Hyogo (Japan), 4. The University of Fukuchiyama (Japan))
Keywords:
morphogenesis,mathematical model,numerical simulation
In many familiar species, organ arrangement is asymmetrical between the left and right, a universal phenomenon. The head-tail axis, dorsal-ventral axis, and left-right axis are the three most basic axes that make up the body of an organism, but the head-tail axis is thought to have been acquired through evolution as a natural response to forward and backward movement, and the dorsal-ventral axis as a natural response to gravity. Once the head-tail axis and dorsal-ventral axis are determined, the third axis is naturally determined from the condition that it is perpendicular to them, but when discussing the direction of the axis, it is difficult to explain that "from a physical point of view, the right is superior to the left". For this reason, elucidating the mechanism of left-right formation is an important remaining issue in biology.
A breakthrough in left-right formation was announced relatively recently by a group including Hiroshi Hamada (RIKEN), who said, "In the early stages of development, cilia protruding from cells cause rotational movement, generating a Node flow in the fluid of the embryo, which results in a difference in the amount of protein upstream and downstream, resulting in the acquisition of left-right." This Node flow model is widely accepted as a universal concept that can be applied to a wide range of cilia-containing organisms. However, since left-right asymmetry also exists in organisms that do not have cilia, such as insects, there must be a mechanism for left-right asymmetry formation that arises from a mechanism other than the Node flow.
Epithelial tissue morphogenesis requires morphologic changes such as migration or deformation of individual epithelial cells constituting the tissue. To reveal 3D morphologic changes of the cells contributing to the tissue deformation, we constructed a 3D vertex dynamics model in which the hindgut epithelial cells were represented by hexagonal cylinders. Numerical simulations suggested that twisting of individual cells along apico-basal axes can induce the directional tube twist. To see whether the cell twisting predicted by the simulation occurs in vivo, we quantified the cell shape change using time-lapse imaging of the whole hindgut. As a result, the hindgut epithelial cells directionally twist before and during the twisting.
A breakthrough in left-right formation was announced relatively recently by a group including Hiroshi Hamada (RIKEN), who said, "In the early stages of development, cilia protruding from cells cause rotational movement, generating a Node flow in the fluid of the embryo, which results in a difference in the amount of protein upstream and downstream, resulting in the acquisition of left-right." This Node flow model is widely accepted as a universal concept that can be applied to a wide range of cilia-containing organisms. However, since left-right asymmetry also exists in organisms that do not have cilia, such as insects, there must be a mechanism for left-right asymmetry formation that arises from a mechanism other than the Node flow.
Epithelial tissue morphogenesis requires morphologic changes such as migration or deformation of individual epithelial cells constituting the tissue. To reveal 3D morphologic changes of the cells contributing to the tissue deformation, we constructed a 3D vertex dynamics model in which the hindgut epithelial cells were represented by hexagonal cylinders. Numerical simulations suggested that twisting of individual cells along apico-basal axes can induce the directional tube twist. To see whether the cell twisting predicted by the simulation occurs in vivo, we quantified the cell shape change using time-lapse imaging of the whole hindgut. As a result, the hindgut epithelial cells directionally twist before and during the twisting.