Cell-type atlas and neuronal connectome of the Platynereis dumerilii three-day-old larva
ZooCELL 1st Practical Course | 03-14 February 2025, COS and EMBL, Heidelberg
What is a larva?
larva
noun ˈlär-və
plural larvae ˈlär-(ˌ)vē, also larvas
1: the immature, wingless, and often wormlike feeding form that hatches from the egg of many insects, alters chiefly in size while passing through several molts, and is finally transformed into a pupa or chrysalis (see chrysalis sense 1a) from which the adult emerges
2: the early form of an animal (such as a frog or sea urchin) that at birth or hatching is fundamentally unlike its parent and must metamorphose before assuming the adult characters
What is a larva?
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 😎
What is a larva?
Platynereis dumerilii
- a gonochorostic species
- lecitotrophic non-feeding larvae
- free-swimming planktonic stage
Platynereis massiliensis
- a protandric hermaphrodite
- lecitotrophic direct development in brood tubes
- absence of a free-swimming stage
A real larva vs. a blob
Platynereis dumerilii
Platynereis massiliensis
“A larva [in a marine invertebrate] is a post-embryonic life-cycle stage that is freely swimming and can be lost during evolution”
Whole-body volume EM of an entire three-day-old larva
Whole-body volume EM of an entire three-day-old larva
Synaptic connectome
Whole-body coordination of cilia
Whole-body coordination of cilia
No arrest in polycystin receptor mutant
UV response in Platynereis larvae
UV response in Platynereis larvae
Brain ciliary photoreceptors with ramified cilia
Reduced ciliary compartment in c-opsin1 mutants
UV avoidance is dependent on c-opsin1
Head neuropils and connectivity
Circuitry of ciliary photoreceptors
Circuitry of ciliary photoreceptors
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
An unusual guanylyl cyclase in the cPRCs
NIT-GC1 RNA
NIT-GC1 protein
An unusual guanylyl cyclase in the cPRCs
NIT-GC1 producs cGMP upon NO addition
NIT-GC morphants have altered circuit activity
Mathematical modelling of the circuit
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
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