2023/07/13
Keio University
Nozomi Totsuka, a first-year student in the Doctoral Programs at the Graduate School of Science and Technology, Keio University, Professor Kotaro Oka and Associate Professor Koji Hotta of the Faculty of Science and Technology at the same university, in collaboration with Professor Satoshi Sawai and Dr. Satoshi Kuwana of the Graduate School of Arts and Sciences, The University of Tokyo, and Professor Yasunori Sasakura of the Shimoda Marine Research Center, University of Tsukuba, have discovered a phenomenon in which cells break through the epidermis and emerge from the body during ascidian metamorphosis (cell extrusion), and have clarified the process by which these extracorporeal cells are replaced.
The body of an ascidian is surrounded by cells thought to be involved in biological defense, and the type of these cells differs depending on the developmental stage. Before metamorphosis, they are protected by maternally derived cells (test cells), while adults utilize cells they produce themselves (bladder cells). However, when and how these cells are replaced has long been a mystery. In this study, the researchers successfully controlled the timing of ascidian metamorphosis using mechanical stimulation and filmed the replacement of these extracorporeal cells. They revealed for the first time that bladder cells are formed by the extrusion of specific mesenchymal cells from the body in the early stages of metamorphosis, and that the subsequent shedding of the maternally derived test cells allows for a smooth replacement of the extracorporeal cells. This replacement of extracorporeal cells is a phenomenon unparalleled in other organisms. These findings also provide insights that will help to understand the mechanism by which external mechanical stimuli are converted into various chemical signals within a living organism.
These findings were published in the international journal of developmental biology, Developmental Dynamics , on June 21, 2023.
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