Graduate School of Frontier Biosciences, Osaka University


Colloquium 201

Speaker Toshihiro Aramaki (Resercher /Laboratory of Pattern Formation)
Title Bioelectrical signal regulates organ size
Speaker Keisuke Matsuda (6th year student in Faculty of Medicine, Osaka Univ. / Laboratory of Pattern Formation)
Title TBC
Date Wed., December 5, 2018, 12:15~13:00
Place 2F Seminar room, BioSystems Building
Host Contact:Shigeru Kondo(Prof. of Laboratory of Pattern Formation)        
Tel :7975

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Bioelectrical signal regulates organ size

There have been numerous researches and findings for embryogenesis, on the other hand, how to decide the body proportions in adult animals has been little understood. It is generally considered that the shape of the adult vertebrate depends on the form of their skeleton. In this study, however, we found that the fin size of zebrafish is controlled independently of the bone.
 Interestingly, some previous studies proved that certain ion channels participate in morphogenesis. In zebrafish, hyperactivation of K+ channel induces elongation of the fin and the fin-ray bone, and decrease of connexin function shortens both of them. Since K+ channels and connexins are known to be involved in formation and propagation of membrane potential respectively, it can be presumed that the fin cells use the electrical principle to measure the organ size.
 To elucidate the mechanisms of this bioelectrical scaling, first we tried to identify responsible cells for the morphological changes using transgenic techniques. Surprisingly, K+ channel hyperactivation in keratinocytes induced elongation of the fin, but the fin-ray bones looked normal. Conversely, connexin loss-of-function in osteoblasts resulted in shortened fin-ray bones, but normal size of the fin. Furthermore, combining the above two conditions, the double transgenic zebrafish showed elongated fin and shortened fin-ray bones. These results indicate that the fin size and the fin-ray length are regulated independently, despite using same mechanisms mediated by membrane potential.