RESUMEN
Throughout vertebrates, cerebrospinal fluid-contacting neurons (CSF-cNs) are ciliated cells surrounding the central canal in the ventral spinal cord. Their contribution to modulate locomotion remains undetermined. Recently, we have shown CSF-cNs modulate locomotion by directly projecting onto the locomotor central pattern generators (CPGs), but the sensory modality these cells convey to spinal circuits and their relevance to innate locomotion remain elusive. Here, we demonstrate in vivo that CSF-cNs form an intraspinal mechanosensory organ that detects spinal bending. By performing calcium imaging in moving animals, we show that CSF-cNs respond to both passive and active bending of the spinal cord. In mutants for the channel Pkd2l1, CSF-cNs lose their response to bending and animals show a selective reduction of tail beat frequency, confirming the central role of this feedback loop for optimizing locomotion. Altogether, our study reveals that CSF-cNs constitute a mechanosensory organ operating during locomotion to modulate spinal CPGs.
Asunto(s)
Líquido Cefalorraquídeo/citología , Neuronas/citología , Médula Espinal/citología , Animales , Fenómenos Biomecánicos , Movimiento Celular , Líquido Cefalorraquídeo/metabolismo , Femenino , Masculino , Mecanorreceptores/citología , Mecanorreceptores/metabolismo , Neuronas/metabolismo , Médula Espinal/química , Médula Espinal/metabolismo , Canales de Potencial de Receptor Transitorio/genética , Canales de Potencial de Receptor Transitorio/metabolismo , Pez Cebra/genética , Pez Cebra/metabolismo , Proteínas de Pez Cebra/genética , Proteínas de Pez Cebra/metabolismoRESUMEN
Three new bastadins, bastadin 25 (1), 15-O-sulfonatobastadin 11 (2), and bastadin 26 (3), were isolated from a MeOH extract of the Australian marine sponge Ianthella flabelliformis. Their structures were determined by interpretation of 1D and 2D NMR spectra and mass spectrometry. Bastadin 26 (3) showed potent affinity for the guinea pig delta-opioid receptors with a K(i) value of 100 nM. The other two bastadins had a 100-fold lower affinity. The three compounds were also tested for their affinity to guinea pig micro- and kappa-opioid receptors and shown to have either no affinity or only very weak affinity toward both of these opioid receptors.
Asunto(s)
Péptidos Cíclicos/aislamiento & purificación , Péptidos Cíclicos/farmacología , Poríferos/química , Receptores Opioides delta/efectos de los fármacos , Algoritmos , Animales , Australia , Encéfalo/efectos de los fármacos , Cobayas , Estructura Molecular , Resonancia Magnética Nuclear Biomolecular , Péptidos Cíclicos/química , Receptores Opioides kappa/efectos de los fármacos , Receptores Opioides mu/efectos de los fármacosRESUMEN
Cyclic tetrapeptides are a class of natural products that have been shown to have broad ranging biological activities and good pharmacokinetic properties. In order to synthesise these highly strained compounds a ring contraction strategy had previously been reported. This strategy was further optimised and a suite of techniques, including the Edman degradation and mass spectrometry/mass spectrometry, were developed to enable characterisation of cyclic tetrapeptide isomers. An NMR solution structure of a cyclic tetrapeptide was also generated. To illustrate the success of this strategy a library of cyclic tetrapeptides was synthesised.