Biology subjects

Fujibayashi, M.

Publications and source records attributed to Fujibayashi, M..

4 recordsLinked to original sources

bioRxiv2025

High-Throughput Assessment of Vocal Modulation Following Chemogenetic Inhibition in Songbirds

Chemogenetic tools that enable temporary and repeatable manipulation of neuronal activity have become essential for studying the precise neural underpinning of animal behavior. However, their application has so far been limited to songbirds, which are widely used to study behaviors related to vocal communication. In this study, we applied and evaluated designer receptors exclusively activated by designer drugs (DREADD)-mediated neural suppression in songbirds brains, focusing on its impacts on vocalizations. We found that neuronal activity in zebra finches (Taeniopygia guttata) can be effectively suppressed both in vitro and in vivo using the inhibitory DREADD by its ligand deschloroclozapine (DCZ). By establishing a high-throughput system for recording and analyzing their vocalizations, we systematically assessed the effects of DREADD-mediated suppression on song behavior. Inhibiting HVC in zebra finches led to a reduction in song production number for approximately 90 min and altered phonological features over a longer time course. Notably, the concentration of DCZ required to induce robust effects on song behaviors was higher than doses typically used in mice. Furthermore, suppression of HVC or Area X in Bengalese finches (Lonchura striata domestica) produced a distinct effect on song features, suggesting species-specific responses to chemogenetic intervention. These findings refine the use of chemogenetic tools in songbirds and provide new insights into the neural mechanisms underlying vocal communication.

neuroscience↗

bioRxiv2024

KAI2-dependent signaling controls vegetative reproduction in Marchantia polymorpha through activation of LOG-mediated cytokinin synthesis

Marchantia polymorpha reproduces vegetatively (asexually) by producing propagules known as gemmae within gemma cups and sexually through spores. We previously reported that KARRIKIN INSENSITIVE 2 (KAI2)-dependent signaling promotes gemma cup and gemma formation. KAI2A perceives unidentified endogenous ligand(s), tentatively referred to as KAI2 ligands (KL). Perception of KL by KAI2 triggers MAX2-dependent proteolysis of MpSMXL. In this study, we identified genes working downstream of KAI2-dependent signaling in M. polymorpha. We found that KAI2-dependent signaling positively controls the expression of MpLONLEY GUY (MpLOG), encoding a cytokinin biosynthesis enzyme. Disruption of the MpLOG function decreased endogenous cytokinin levels and caused defects similar to KAI2-dependent signaling mutants. Moreover, supplying exogenous cytokinins rescued the defects of Mplog and KAI2-dependent signaling mutants, implying that cytokinins work downstream of KAI2-dependent signaling. Activation of MpLOG by KAI2-dependent signaling occurs in a highly cell-type-specific manner, leading to cell-specific induction of GEMMA CUP-ASSOCIATED MYB1 (GCAM1), the master regulator of vegetative reproduction of M. polymorpha. We propose a genetic cascade, starting from KAI2-dependent signaling, that promotes vegetative reproduction through the induction of MpLOG and GCAM1. The interaction between KAI2-dependent signaling and cytokinin in M. polymorpha provides a novel insight into the function and evolution of KAI2-dependent signaling.

plant biology↗

bioRxiv2023

MCFBM: a behavioral analysis system enabling objective inference of songbirds' attention during social interactions

Understanding animal behavior is crucial in behavioral neuroscience, which aims to unravel the mechanism driving these behaviors. A milestone in this field is the analysis of behavioral reactions among animals engaging in social interactions. Although many studies have revealed the fundamental roles of social interaction in social learning, the behavioral aspects of these interactions remain poorly understood, largely due to the lack of tools for analyzing complex behaviors and the attention of subjects in naturalistic, free-moving conditions. Here, we introduce a high-precision system for behavior analysis in songbirds using a marker-based motion capture technique. This system accurately tracks the body location and head direction of freely moving finches and is applicable to multiple subjects during social interaction. With this system, we have quantitatively analyzed behaviors of zebra finches (Taeniopygia guttata) related to visual attention. Our analysis revealed variations in the use of right and left eyes, as well as the duration of sight, among the individuals presented. Further analysis and comparison of their behaviors during both virtual and live presentation identified the similarities and differences in their behavioral reactions. Additionally, we observed changes in their behavioral reactions during a conditioned learning paradigm. This system provides an efficient and easy-to-use tool for advanced behavioral analysis in songbirds, providing an objective method to infer their focus of attention.

animal behavior and cognition↗

bioRxiv2022

KARRIKIN INSENSITIVE2 (KAI2)-dependent signaling pathway controls vegetative reproduction in Marchantia polymorpha

In vegetative reproduction of Marchantia polymorpha, propagules, called gemmae, are formed in gemma cups. Despite its significance for survival, control of gemma and gemma cup formation by environmental cues is not well understood. We show here that the number of gemmae formed in a gemma cup is a genetic trait. Gemma formation starts from the central region of the floor of the gemma cup, proceeds to the periphery, and terminates when the appropriate number of gemmae are initiated. The MpKARRIKIN INSENSITIVE2 (MpKAI2)-dependent signaling pathway promotes gemma cup formation and gemma initiation. The number of gemmae in a cup is controlled by modulating the ON/OFF switch of the KAI2-dependent signaling. Termination of the signaling results in the accumulation of MpSMXL, a suppressor protein. In the Mpsmxl mutants, gemma initiation continues, leading to the formation of a highly increased number of gemmae in a cup. Consistent with its function, the MpKAI2-dependent signaling pathway is active in gemma cups where gemmae initiate, as well as in the notch region of the mature gemma and midrib of the ventral side of the thallus. In this work, we also show that GEMMA CUP-ASSOCIATED MYB1 works downstream of this signaling pathway to promote gemma cup formation and gemma initiation. We also found that the availability of potassium affects gemma cup formation independently from the KAI2-dependent signaling pathway in M. polymorpha. We propose that the ancestral function of the KAI2-dependent signaling pathway may be to optimize vegetative reproduction by adapting to the environment.

plant biology↗