Studies on skeletal muscle atrophy in space ---what zebrafish experienced in a space tour

Fuminori Sato1, Choi Minyong1, Zi Wang1, Quan Wu2, Ikumi Fujita2, Misato Iwase1, Satoko Uchida3, Toru Sakimura3, Yasushi Kono4, Masaki Shirakawa5, Fumiaki Tanigaki5, Masahiro Chatani6, Akira Kudo6, Akihisa Takahashi7, Junya Kobayashi8, Kiyomi Imamura9, Terumi Horiuchi9, Satoshi Furukawa5, Tadashi Muratani10, Sumio Sugano11, Yutaka Suzuki9, Fumio Matsuzaki2, Koichi Kawakami12, and Atsuko Sehara-Fujisawa1

1.Ins tute for Fron er Life and Medical Sciences, Kyoto University
2.RIKEN Center for Developmental Biology
3.Japan Space Forum
4.Mitsubishi Heavy Industries
5.Japan Aerospace Explora on Agency
6.Graduate School of Bioscience and Biotechnology, Tokyo Ins tute of Technology
7.Gunma University Heavy Ion Medical Center
8.Radia on Biology Center, Kyoto University
9.Graduate School of Fron er Sciences, The University of Tokyo
10.Faculty of Medicine, Tsukuba University
11.The Ins tute of Medical Science, The University of Tokyo,
12.Na onal Ins tute of Gene cs, Japan

Amygdala, a center of decision-making, memory and emo onal responses, is one of key components of the anxiety circuit. We are interested in dissec ng precise neural circuits and understanding the molecular mechanism of anxiety using zebrafish. From neuroanatomical and hodological studies in zebrafish, it has been proposed that the medial zone of dorsal telencephalon (Dm) is a homolog of the mammalian amygdala. The emx3 gene, encoding a homeodomain transcrip onal factor, is expressed in neurons in Dm at the adult stage and in the forebrain at the larval stage. In order to test whether, emx3 is essen al for func ons of the Dm neurons, we generated emx3 homozygous mutants using the CRISPR/Cas9 method and analyzed them for an anxiety-related behavior, namely novel tank assay. We found the emx3 homozygous mutants showed severer phenotypes in the novelty-evoked anxiety behavior, compared to sibling controls. This indicates that the emx3 gene may be involved in reduc on of anxiety. We think that these func ons may possibly be correlated with anxiety disorders that show an excessive fear response and/or increased anxiety. We are inves ga ng how the emx3 gene knockout a ects the func on and forma on of the emx3-expressing neurons in Dm.