Reactive oxygen species (ROS) impact many physiological processes in animals or plants, but its production by NADPH oxidases is strictly regulated because of extremely high reactivity. Many plant receptor pathways are known as critical regulators of ROS production, but how they spatially control ROS production is yet to be clarified.

Fujita et al. (2020) established a phospho-signaling pathway that integrates direct, rapid activation of ROS production with positional information and transcriptional changes to form proper diffusion barriers. Firstly, the authors presented a direct connection from a peptide-receptor complex to NADPH oxidases via a membrane-anchored kinase by biochemically. Next, the authors focused on the membrane-anchored kinase that localizes on the plasma membrane in a polar fashion. Manipulation of the kinase localization successfully showed that this biased distribution of the kinase protein gave the positional cue, which enables the SCHENGEN pathway to activate only one side of the Casparian strip at micrometer-scale precision. This work would contribute to highlight how other receptor pathways could control local ROS production.

This work was mainly done by Dr. Satoshi Fujita (former postdoctoral fellow in University of Lausanne, currently NIG research fellow) in Prof. Niko Geldner’s group with a collaboration with the Central imaging, Electron microscope, and Genomics facilities of University of Lausanne, Swiss Institute of bioinformatics, Prof. Jörg Kudla’s group at University of Munster and Dr. Gwyneth Ingram’s group at University of Lyon.

This work was aided by grants no. 31003A_156261 and 310030E_176090 (N.G.), from the Swiss National Science Foundation, an ERC Consolidator Grant (616228-ENDOFUN) (N.G.), DFG grant (Ku931/14-1 (J.K.)) FEBS long-term fellowship (P.M.), EMBO long-term fellowship (R.U., M.B.), Marie Curie postdoctoral fellowship (T.G.A,), Fundacion Alfonso Martin Escudero fellowship (V.G.D.), and a Japan Society for the Promotion of Science (JSPS) fellowship (S.F.).

Figure: Plant roots have a lignin-based diffusion barrier, namely Casparian strips. Localized ROS production (EM pictures) by asymmetrical signal activation (schematic model) sustains functional barrier formation.

• RNA seq data(transcriptional changes after CIF peptide treatment)

Peristalsis is indispensable for physiological function of the gut. The enteric nervous system (ENS) plays an important role in regulating peristalsis. While the neu- ral network regulating anterograde peristalsis, which migrates from the oral end to the anal end, is charac- terized to some extent, retrograde peristalsis re- mains unresolved with regards to its neural regula- tion. Using forward genetics in zebrafish, we reveal that a population of neurons expressing a hyperpo- larization-activated nucleotide-gated channel HCN4 specifically regulates retrograde peristalsis. When HCN4 channels are blocked by an HCN channel inhibitor or morpholinos blocking the protein ex- pression, retrograde peristalsis is specifically attenu- ated. Conversely, when HCN4(+) neurons expressing channelrhodopsin are activated by illumination, retrograde peristalsis is enhanced while anterograde peristalsis remains unchanged. We propose that HCN4(+) neurons in the ENS forward activating sig- nals toward the oral end and simultaneously stimu- late local circuits regulating the circular muscle.

Figure1: Gastrointestinal neurons expressing a hyperpolarization-activated nucleotide- gated channel HCN4 regulate retrograde peristalsis, which migrates from the anal end to the oral end of the gut.

Figure2: Visualization of neurons (red) and HCN4-expressing neurons (green) in the zebrafish intestine.

Press release

Press release (In Japanese only)

Virtual realities are powerful tools to analyze and manipulate interactions between animals and their environment and to enable measurements of neuronal activity during behavior. In many species, however, optical access to the brain and/or the behavioral repertoire are limited. We developed a high-resolution virtual reality for head-restrained adult zebrafish, which exhibit cognitive behaviors not shown by larvae. We noninvasively measured activity throughout the dorsal telencephalon by multiphoton calcium imaging. Fish in the virtual reality showed regular swimming patterns and were attracted to animations of conspecifics. Manipulations of visuo-motor feedback revealed neurons that responded selectively to the mismatch between the expected and the actual visual consequences of motor output. Such error signals were prominent in multiple telencephalic areas, consistent with models of predictive processing. A virtual reality system for adult zebrafish therefore provides opportunities to analyze neuronal processing mechanisms underlying higher brain functions including decision making, associative learning, and social interactions.

Source: Kuo-Hua Huang , et al., Published: 02 March 2020
DOI: 10.1038/s41592-020-0759-2

Fig: Virtual reality system to analyze neural activity and behavior in adult zebrafish
A: Head fixation with L-shaped bars
B: Virtual reality projected by three projectors onto a panoramic screen
C: Setup for virtual reality and two-photon imaging
D: Virtual reality seen by the head-fixed zebrafish

• This study is based on the previous study.