Biology subjects

Porta-de-la-Riva, M.

Publications and source records attributed to Porta-de-la-Riva, M..

9 recordsLinked to original sources

bioRxiv2026

Neural sensing of surface traction modulates proprioceptive activity and locomotion in Caenorhabditis elegans

Locomotion -- whether walking, running, or crawling -- depends on the precise coordination of forces between the body and its surroundings. Two critical factors in this process are the force that resists the relative motion between two bodies, and mechanosensation, the bodys ability to sense and respond to mechanical forces. Together, they allow organisms to move efficiently, adapt to varying environments, and maintain balance. Here we show that the gentle touch receptor neurons (TRNs) in the Caenorhabditis elegans body wall are sensitive to dynamic surface traction. Using a combination of calcium recordings and traction force microscopy in freely moving animals, microfluidics, and whole connectome computer simulations, we show that MEC-4 DEG/ENaC ion channel activity depends on the crawling velocity and friction force. Mutations disrupting MEC-4 activity and body wall mechanoreceptor function produce lethargic worms with impaired proprioceptive regulation, suggesting functional coupling between surface mechanoreceptors and proprioceptors. Our data reveal a new role for classical touch receptors in locomotion and critically define the mechanical modality sensed by skin mechanosensors.

neuroscience↗

bioRxiv2026

Bright calcium-modulated bioluminescent indicators for activity imaging and red photon-assisted synaptic transmission

Bioluminescent calcium sensors have unique uses in neuroscience and neuroengineering, enabling noninvasive imaging of neuronal activity and contactless activation of opsin-expressing neurons. However, the speed, range, and robustness of non-invasive imaging and rewiring or neuronal activity are limited by the radiance and dynamic range of existing bioluminescent calcium sensors. Here, we report the stepwise engineering of improved cyan-excitable red fluorescent proteins (mCyRFP4 and dCyRFP4), an improved red bioluminescent protein based on NanoLuc and CyRFP4 (Antares3), and an improved bioluminescent calcium sensor based on Antares3 (CaMBI3). Antares3 is 3-fold brighter than its predecessor, while CaMBI3 responds with an overall dynamic range of 24-fold, enabling high-sensitivity detection of calcium dynamics in muscle and neuronal tissues in vivo. Finally, a CaMBI3 variant and a red-shifted opsin ChRmine enabled red photon-assisted synaptic transmission in C. elegans. CaMBI3 thus facilitates genetically targeted non-invasive imaging and rewiring of neural activity in living animals.

neuroscience↗

bioRxiv2024

Mechanical load conditions the spectrin network to `run-on' proteolysis and promotes early onset neurodegeneration

The correct homeostasis of the neuronal cytoskeleton and its dynamics is important for health and disease. Forces constantly act on the neurons in our body, leading to subtle axonal deformations and length changes. The spectrin cytoskeleton is known as a key player that protects neurons against mechanical damage. How the spectrin cytoskeleton changes with age and how it influences mechanoprotection in aging animals is not well understood. Using an interdisciplinary approach, we show that age causes a loss of proprioception during the first few days of adulthood in C. elegans via spectrin unfolding, loss of mechanical tension and degradation of the spectrin cytoskeleton. Guided by a proteomic screen to identify potential spectrin binding partners, we found that this early-onset neurodegeneration can be suppressed in clp-1 mutants and by targeted expression of an engineered chaperone derived from human B-crystallin. Our data suggest that the spectrin cytoskeleton is sensitized to proteolytic damage by calcium-sensitive proteases when mechanical stresses conspires with high-calcium concentrations as in proprioceptive signaling. These results may have implications for the etiology of diseases in which high calcium dynamics and mechanical stress co-incide.

neuroscience↗

bioRxiv2023

FLInt: Single Shot Safe Harbor Transgene Integration via Fluorescent Landmark Interference

The stable incorporation of transgenes and recombinant DNA material into the host genome is a bottleneck in many bioengineering applications. Due to the low efficiency, identifying the transgenic animals is often a needle in the haystack. Thus, optimal conditions require efficient screening procedures, but also known and safe landing sites that do not interfere with host expression, low input material and strong expression from the new locus. Here, we leverage an existing library of{approx} 300 different loci coding for fluorescent markers that are distributed over all 6 chromosomes in Caenorhabditis elegans as safe harbors for versatile transgene integration sites using CRISPR/Cas9. We demonstrated that a single crRNA was sufficient for cleavage of the target region and integration of the transgene of interest, which can be easily followed by loss of the fluorescent marker. The same loci can also be used for extrachromosomal landing sites and as co-CRISPR markers without affecting body morphology or animal behavior. Thus, our method overcomes the uncertainty of transgene location during random mutagenesis, facilitates easy screening through fluorescence interference and can be used as co-CRISPR markers without further influence in phenotypes.

genetics↗

bioRxiv2022

A rigidity phase transition of Stomatin condensates governs a switch from transport to mechanotransduction

A large body of work suggests that biomolecular condensates ensuing from liquid-liquid phase separation mature into various material states. How this aging process is controlled and if the naive and mature phases can have differential functions is currently unknown. Using Caenorhabditis elegans as a model, we show that MEC-2 Stomatin undergoes a rigidity phase transition during maturation from fluid to viscoelastic, glass-like condensates that facilitate either transport or mechanotransduction. This switch is promoted by the SH3 domain of UNC-89/Titin/Obscurin through a direct interaction with MEC-2 and suggests a physiological role for a percolation transition in force transmission during body wall touch. Together, our data demonstrate a novel function for rigidity maturation during mechanotransduction and a previously unidentified role for Titin homologs in neurons.

cell biology↗

bioRxiv2022

Volumetric bioluminescence imaging of cellular dynamics with deep learning based light-field reconstruction

The application of genetically encoded fluorophores for microscopy has afforded one of the biggest revolutions in the biosciences. Bioluminescence microscopy is an appealing alternative to fluorescence microscopy, because it does not depend on external illumination, and consequently does neither produce spurious background autofluorescence, nor perturb intrinsically photosensitive processes in living cells and animals. The low quantum yield of known luciferases, however, limit the acquisition of high signal-noise images of fast biological dynamics. To increase the versatility of bioluminescence microscopy, we present an improved low-light microscope in combination with deep learning methods to increase the signal to noise ratio in extremely photon-starved samples at millisecond exposures for timelapse and volumetric imaging. We apply our method to image subcellular dynamics in mouse embryonic stem cells, the epithelial morphology during zebrafish development, and DAF-16 FoxO transcription factor shuttling from the cytoplasm to the nucleus under external stress. Finally, we concatenate neural networks for denoising and light-field deconvolution to resolve intracellular calcium dynamics in three dimensions of freely moving Caenorhabditis elegans with millisecond exposure times. This technology is cost-effective and has the potential to replace standard optical microscopy where external illumination is prohibitive.

bioengineering↗

bioRxiv2021

Deploying photons for communication within neuronal networks

Deficiencies in neurotransmission lead to neurological disorders or misinterpretation of perceived threats. To restore defects in cellular communication, we developed a synthetic, photon-assisted synaptic transmission (PhAST) system. PhAST is based on luciferases and channelrhodopsins that enable the transmission of a neuronal state across space, using photons as neurotransmitters. We demonstrate the ability to overcome synaptic barriers and rescue the behavioral deficit of a genetically engineered glutamate mutant with conditional, Ca2+-triggered photon emission between two cognate neurons of the Caenorhabditis elegans nociceptive avoidance circuit. We also deploy these ingredients for asynaptic transmission between two unrelated cells in a sexually dimorphic neuronal network. Functional PhAST could sensitize otherwise poorly responsive males to touch and hence expand the behavioral repertoire. Our study, thus, establishes a powerful framework for complex photon-based communication between neurons in a living animal, that can readily be expanded to synthetic neuronal networks, organoids or non-invasive brain-machine interfaces.

synthetic biology↗

bioRxiv2021

Mechanical Stretch Inhibition SensitizesProprioceptors to Compressive Stresses

A repetitive gait cycle is an archetypical component within the behavioural repertoire of many if not all animals including humans. It originates from mechanical feedback within proprioceptors to adjust the motorprogram during locomotion and thus leads to a periodic orbit in a low dimensional space. Here, we investigate the mechanics, molecules and neurons responsible for proprioception in Caenorhabditis (C.) elegans to gain insight into how mechanosensation shapes the orbital trajectory to a well-defined limit cycle. We used genome editing, force spectroscopy and multiscale modeling and found that alternating tension and compression with the spectrin network of a single proprioceptor encodes body posture and informs TRP-4/NOMPC and TWK-16/TREK2 homologs of mechanosensitive ion channels during locomotion. In contrast to a widely accepted model of proprioceptive stretch reception, we found that proprioceptors activated under compressive stresses in vivo and in vitro, and speculate that this property is conserved across function and species.

neuroscience↗

bioRxiv2020

Ancestral function of Inhibitors-of-kappaB regulates Caenorhabditis elegans development

Mammalian I{kappa}B proteins (I{kappa}Bs) exert their main function as negative regulators of NF-{kappa}B, a central signaling pathway controlling immunity and inflammation. An alternative chromatin role for I{kappa}Bs has been shown to affect stemness and cell differentiation. However, the involvement of NF-{kappa}B in this function has not been excluded. NFKI-1 and IKB-1 are I{kappa}B homologs in Caenorhabditis elegans, which lacks NF-{kappa}B nuclear effectors. We found that nfki-1 and ikb-1 mutants display developmental defects that phenocopy mutations in Polycomb and UTX-1 histone demethylase, suggesting a role for C. elegans I{kappa}Bs in chromatin regulation. Further supporting this possibility (i) we detected NFKI-1 in the nucleus of cells; (ii) NFKI-1 and IKB-1 bind to histones and Polycomb proteins, (iii) and associate with chromatin in vivo, and (iv) mutations in nfki-1 and ikb-1 alter chromatin marks. Based on these results, we propose that ancestral I{kappa}B inhibitors modulate Polycomb activity at specific gene subsets with an impact on development.

developmental biology↗