We published a new preprint on the mechanism of hydrostatic pressure sensation in marine #zooplankton.
https://www.biorxiv.org/content/10.1101/2023.02.28.530398v1?ct=ct
Click on the toot to see a thread about our findings. 1/9
Hydrostatic pressure is a dominant cue in the sea and many aquatic organisms are known to respond to changes in pressure, however the neuronal mechanisms have remained unclear.
We studied the larvae of the marine #annelid #Platynereis and found that they respond to increases in pressure by increased upward swimming.
#neuroscience
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Luis Bezares, the first author of the study, built custom pressure chambers where he could precisely control pressure levels while imaging the swimming activity of the #larvae.
Larvae showed graded and adaptable responses to relative changes in pressure. Increased pressure led to faster beating of locomotor cilia.
The larvae were extremely sensitive to pressure changes, reacting already to 10-20 mbar increase in pressure, corresponding to 10-20 cm water depth.
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To identify the #neuronal mechanisms, Luis carried out #calcium #imaging experiments and found that the brain ciliary #photoreceptor cells showed graded activation by pressure stimuli.
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Reza Shahidi did #volumeEM on the cilia and we found defects with the ramifications.
6/9
By #connectome analysis, we previously showed that the ciliary photoreceptors synaptically connect through interneurons to the head serotonergic ciliomotor neurons (Ser-h1). Serotonin increases ciliary beating and genetic inhibition of these cells blocked the effect of pressure on cilia, confirming that the pressure signal reaches the ciliated cells via the mapped circuit.
#connectomics
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We propose a model for a pressure gauge in zooplankton, including ciliary photoreceptos as sensors and a circuit linking these to the ciliary band cells, leading to increased beating through the action of serotonin, driving faster upward swimming.
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Currently we are trying to understand what underlies the extreme sensitivity of the ciliary photoreceptors to pressure Stay tuned.
9/9
For this paper, all analyses, plots, code, figures, text and references were made in R (with some analyses in #Fiji)
and are all available on #github
https://github.com/JekelyLab/Bezares_et_al_2023_Pressure
you can clone the entire repo and open the .rproj R project
#rstats #openscience
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These cells have highly ramified #cilia and express a ciliary #opsin 1. Mutant larvae lacking ciliary opsin 1 had smaller and disorganised sensory cilia and reduced pressure responses, confirming that the photoreceptors are the pressure sensors.
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