Whole-body volume EM and synaptic connectome of a segmented marine annelid larva

COS Symposium 2024

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Platynereis dumerilii

breeding culture, full life-cycle
embryos daily, year round
genome sequence
microinjection, transgenesis
neuron-specific promoters and antibodies
knock-out lines
neuronal connectome
whole-body neuronal activity imaging
whole-animal pharmacology by bath application 😎

Whole-body volume EM of an entire three-day-old larva

Head ganglia and neuropils

Synaptic connectome

202 neuronal and 92 non-neuronal cell types

A cell-type-level connectome

UV response in Platynereis larvae

Brain ciliary photoreceptors with ramified cilia

UV avoidance is dependent on UV-absorbing c-opsin1

Reduced ciliary compartment in c-opsin1 mutants

Circuitry of ciliary photoreceptors

Serotonergic neurons to activate cilia

Ser-h1 neurons, EM reconstruction

Strong cPRC activation after UV exposure

UV response is c-opsin1-dependent

Nitric-oxide synthase in postsynaptic interneurons

HCR Transgenic labelling immunostaining

NO is produced in the neuropil after UV stimulation

NOS mutants have altered cPRC response

NOS mutants have altered INRGW response

Ciliary response to UV in wt and NOS mutants

ciliary beat frequency

Swimming speed

NOS mutants show defective UV avoidance

NO signal is short-range

NOS protein in the INNOS dendritic compartment

Two unusual guanylyl cyclases in the cPRCs

NIT-GC1 RNA

NIT-GC1 protein

NIT-GC2 RNA

NIT-GC2 protein

Two unusual guanylyl cyclases in the cPRCs

NIT-GC1 mediates NO-feedback

anti-NIT-GC1 immuno

NIT-GC2 mediates phototransduction

anti-NIT-GC2 immuno

Mathematical modelling of the circuit

Model fitting

wild type

NOS-11

NOS-23

NIT-GC2 mo.

Integration and memory of UV exposure

Synaptic+chemical connectomes -> circuit dynamics and function

Acknowledgements

Heidelberg

Alexandra Kerbl
Sanja Jasek
Emily Savage
Benedikt Dürr
Simone Wolters
Lara Keweloh
Kevin Urbansky
Suat Özbek
Maike Fath
Ibrahim Akhtar

Exeter

Kei Jokura
Emelie Brodrick
Luis A. Bezares-Calderón
Luis Yanez
Victoria Moris
Daniel Thiel
Adam Johnstone