Biology subjects

Caorsi, V.

Publications and source records attributed to Caorsi, V..

5 recordsLinked to original sources

bioRxiv2026

Developmental genetic response of the zooplanktonic tunicate Oikopleura dioica to marine noise pollution.

BackgroundAnthropogenic noise is an emerging threat to marine ecosystems, yet its effects on marine invertebrates, particularly zooplanktonic species, remain poorly understood. Despite increasing evidence of behavioral and physiological impacts in invertebrates, the effects of noise on embryonic development and the molecular mechanisms underlying acoustic responses remain largely unexplored. Here, to address this gap, we investigated the impact of high-intensity underwater noise exposure on embryogenesis of the appendicularian tunicate Oikopleura dioica, a cosmopolitan zooplanktonic tunicate that plays important ecological roles in marine trophic webs and carbon cycling. Under lab-controlled conditions, we examined the effects of experimental noise exposure on early embryogenesis at both morphological and transcriptomic levels using RNA-seq in 8-cell (8c) and early tailbud (ETB) stages. ResultsNoise exposure produced no significant increase in embryo malformations compared to non-exposed controls, indicating substantial phenotypic resilience under laboratory conditions. Interestingly, transcriptomic analyses revealed a rapid molecular response of 70 differentially expressed genes (DEG) already detectable after only 30 minutes of exposure at the 8-cell stage, which became markedly amplified with 700 DEGs by the ETB stage. Together, differential expression, GO enrichment, and co-expression network analyses identified coordinated regulation of processes associated with membrane homeostasis, pyrimidine/CTP metabolism, extracellular matrix organization, cytoskeletal architecture, RNA regulation, translational control, proteostasis, mitochondrial metabolism, and developmental pathways. Importantly, both developmental stages precede the formation of differentiated mechanosensory structures, suggesting that the observed responses are unlikely to reflect conventional sound perception. ConclusionsThese findings provide the first molecular characterization of noise effects during O. dioica embryogenesis and reveal an unexpected molecular sensitivity of O. dioica embryos to underwater noise despite preserved morphological development. The transcriptional signatures support a mechanobiological framework in which acoustic exposure may directly perturb cellular mechanical homeostasis through membrane-and cytoskeleton-associated processes, triggering compensatory stress-adaptation responses involving proteostasis, RNA regulation, and metabolic reprogramming. Together, these findings establish O. dioica as a valuable emerging model for investigating the developmental and evolutionary consequences of acoustic pollution in marine ecosystems.

developmental biology↗

bioRxiv2023

Robust and fast multicolor Single Molecule Localization Microscopy using spectral separation and demixing

Single Molecule Localization Microscopy (SMLM) is a straightforward approach to reach sub-50 nm resolution using techniques such as Stochastic Optical Reconstruction Microscopy (STORM) or DNA-Point Accumulation for Imaging in Nanoscale Topography (PAINT), and to resolve the arrangement of cellular components in their native environment. However, SMLM acquisitions are slow, particularly for multicolor experiments where channels are usually acquired in sequence. In this work, we evaluate two approaches to speed-up multicolor SMLM using a module splitting the fluorescence emission toward two cameras: simultaneous 2-color PAINT (S2C-PAINT) that images spectrally-separated red and far-red imager strands on each camera, and spectral demixing STORM (SD-STORM) that uses spectrally-close far-red fluorophores imaged on both cameras before assigning each localization to a channel by demixing. For each approach, we carefully evaluate the crosstalk between channels using three types of samples: DNA origami nanorulers of different sizes, single-target labeled cells, or cells labeled for multiple targets. We then devise experiments to assess how crosstalk can potentially affect the detection of biologically-relevant subdiffraction patterns. Finally, we show how these approaches can be combined with astigmatism to obtain three-dimensional data, and how SD-STORM can be extended three-color imaging, making spectral separation and demixing attractive options for robust and versatile multicolor SMLM investigations.

cell biology↗

bioRxiv2020

Myosin 1b Flattens and Prunes Branched Actin Filaments.

Motile and morphological cellular processes require a spatially and temporally coordinated branched actin network that is controlled by the activity of various regulatory proteins including the Arp2/3 complex, profilin, cofilin and tropomyosin. We have previously reported that myosin 1b regulates the density of the actin network in the growth cone. Using in vitro F-actin gliding assays and total internal reflection fluorescence (TIRF) microscopy we show in this report that this molecular motor flattens the Arp2/3-dependent actin branches up to breaking them and reduces the probability to form new branches. This experiment reveals that myosin 1b can produce force sufficient enough to break up the Arp2/3-mediated actin junction. Together with the former in vivo studies, this work emphasizes the essential role played by myosins in the architecture and in the dynamics of actin networks in different cellular regions. Short summaryUsing in vitro F-actin gliding assays and total internal reflection fluorescence (TIRF) microscopy we show that myosin flattens the Arp2/3-dependent actin branches up to breaking them and reduces the probability to form new branches

biophysics↗

bioRxiv2019

Actin shells control buckling and wrinkling of biomembranes

Global changes of cell shape under mechanical or osmotic external stresses are mostly controlled by the mechanics of the cortical actin cytoskeleton underlying the cell membrane. Some aspects of this process can be recapitulated in vitro on reconstituted actin-and-membrane systems. In this paper, we investigate how the mechanical properties of a branched actin network shell, polymerized at the surface of a liposome, control membrane shape when the volume is reduced. We observe a variety of membrane shapes depending on the actin thickness. Thin shells undergo buckling, characterized by a cup-shape deformation of the membrane that coincides with the one of the actin network. Thick shells produce membrane wrinkles, but do not deform their outer layer. For intermediate micrometerthick shells, wrinkling of the membrane is observed, and the actin layer is slightly deformed. Confronting our experimental results with a theoretical description, we determine the transition between buckling and wrinkling depending on the thickness of the actin shell and the size of the liposome. We thus unveil the generic mechanism by which biomembranes are able to accommodate their shape against mechanical compression, through thickness adaptation of their cortical cytoskeleton.

biophysics↗

bioRxiv2018

A direct proof that sole actin dynamics drive membrane deformations

Cell membrane deformations are crucial for proper cell function. Specialized protein assemblies initiate inward or outward membrane deformations that turn into, for example, filopodia or endocytic intermediates. Actin dynamics and actin-binding proteins are involved in this process, although their detailed role remains controversial. We show here that a dynamic, branched actin network is sufficient, in absence of any membrane-associated proteins, to initiate both inward and outward membrane deformation. With actin polymerization triggered at the membrane of liposomes, we produce inward filopodia-like structures at low tension, while outward endocytosis-like structures are robustly generated regardless of tension. Our results are reminiscent of endocytosis in mammalian cells, where actin polymerization forces are required when membrane tension is increased, and in yeast, where they are always required to overcome the opposing turgor pressure. By combining experimental observations with physical modeling, we propose a mechanism for actin-driven endocytosis under high tension or high pressure conditions.

biophysics↗