Mechanism of barotaxis in marine zooplankton
NYU
March 19, 2024
Responses of marine animals to changes in pressure
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 😎
Pressure response in Platynereis larvae
Precise control of pressure in the pressure chamber
Pressure response is graded
Swimming speed increases, trajectories straighten
ctr
pressure
Ciliary beating increases under pressure
Which cells respond to pressure?
Microscopy pressure chamber 
Calcium imaging 
Pressure is sensed by photoreceptors with ramified cilia
Photoreceptor responses to pressure are graded
Defects of pressure response in c-opsin1 mutants
Reduced ciliary compartment in c-opsin1 mutants
Defects of ciliary ultrastructure in c-opsin1 mutants
Whole-body volume EM of an entire three-day-old larva
Synaptic connectome
Synaptic connectome
Head neuropils and connectivity
Circuitry of ciliary photoreceptors
Pressure increases ciliary beating through serotonergic cells
Mechanism of barotaxis
UV response in Platynereis larvae
UV avoidance is dependent on c-opsin1
How can cPRCs mediate two responses with opposing sign?
c-opsin1-dependent UV response
Strong cPRC activation after UV exposure
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 and motoneuron response
NOS mutants show defective UV avoidance
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
NIT-GC2 mediates phototransduction
Mathematical modelling of the circuit
Model fitting
wild type
NOS-11
NOS-23
NIT-GC2 mo.
Integration and memory of UV exposure
Up or down?
‘front-wheel drive’ head cilia fast
‘rear-wheel drive’ head cilia slow
but reviewer 2 asked us to …
ciliary beat frequency
Swimming speed
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
