Biology subjects

Ricci, C.

Publications and source records attributed to Ricci, C..

4 recordsLinked to original sources

bioRxiv2024

The Ca2+-activated Cl- channel TMEM16B shapes the response time course of olfactory sensory neurons

Mammalian olfactory sensory neurons (OSNs) generate an odorant-induced response by sequentially activating two ion channels, which are in their ciliary membranes. First, a cationic, Ca2+-permeable cyclic nucleotide-gated channel is opened following odorant stimulation via a G protein-coupled transduction cascade and an ensuing raise in cAMP. Second, the increase in ciliary Ca2+ opens the excitatory Ca2+-activated Cl- channel TMEM16B that carries most of the odorant-induced receptor current. While the role of TMEM16B in amplifying the response has been well established, it is less understood how this secondary ion channel contributes to response kinetics and action potential generation during single as well as repeated stimulation and, on the other hand, which response properties the CNG channel determines. We first demonstrate that basic membrane properties such as input resistance, resting potential and voltage-gated currents remained unchanged in OSNs that lack TMEM16B. The CNG channel predominantly determines the response delay and adaptation during odorant exposure, while the absence of the Cl- channels shortens both the time the response requires to reach its maximum as well as to terminate after odorant stimulation. This faster response termination in Tmem16b knockout OSNs allows them, somewhat counterintuitively, to fire action potentials more reliably when stimulated repeatedly in rapid succession, a phenomenon that occurs both in isolated OSNs as well as in OSNs within epithelial slices. Thus, while the two olfactory ion channels act in concert to generate the overall response, each one controls specific aspects of the odorant-induced response.

physiology↗

bioRxiv2023

Proteomics reveals how the tardigrade damage suppressor protein teaches transfected human cells to survive UV-C stress

The genome sequencing of the tardigrade Ramazzottius varieornatus revealed a unique nucleosome-binding protein, named Damage Suppressor (Dsup), which resulted to be crucial for the extraordinary abilities of tardigrades in surviving extreme stresses, such as UV. Evidence in Dsup transfected human cells, suggests that Dsup mediates an overall response of DNA damage signaling, DNA repair and cell cycle regulation resulting in an acquired resistance to stress. Given these promising outcomes, our study attempts to provide a wider comprehension of the molecular mechanisms modulated by Dsup in human cells, and to explore the Dsup-activated molecular pathways under stress. We performed a differential proteomic analysis of Dsup-transfected and control human cells, under basal condition and at 24-hour recovery after exposure to UV-C. We demonstrate by enrichment and network analyses, for the first time, that even in the absence of external stimuli and more significantly after stress, Dsup activates mechanisms involved with the Unfolded Protein Response, the mRNA processing and stability, cytoplasmic stress granules, the DNA Damage Response and the telomere maintenance. In conclusion, our results shed new light on Dsup-mediated protective mechanisms, and increase our knowledge of the molecular machineries of extraordinary protection against UV-C stress.

cell biology↗

bioRxiv2023

Shedding light on human olfaction: electrophysiological recordings from sensory neurons in acute slices of olfactory epithelium

The COVID-19 pandemic brought attention to our limited understanding of human olfactory physiology. While the cellular composition of the human olfactory epithelium is similar to that of other vertebrates, its functional properties are largely unknown. We prepared acute slices of human olfactory epithelium from nasal biopsies and used the whole-cell patch-clamp technique to record electrical properties of cells. We measured voltage-gated currents in human olfactory sensory neurons and supporting cells, and action potentials in neurons. Additionally, inward currents and action potentials responses of neurons to a phosphodiesterase inhibitor indicated that the transduction cascade involves cAMP as a second messenger. Furthermore, responses to odorant mixtures demonstrated that the transduction cascade was intact in this preparation. This study provides the first electrophysiological characterization of olfactory sensory neurons in acute slices of the human olfactory epithelium, paving the way for future research to expand our knowledge of human olfactory physiology.

neuroscience↗

bioRxiv2020

Shifting Baselines: Repeat bleaching drives coral physiotypes through environmental legacy and cellular memory

O_LIGlobal climate change is altering coral reef ecosystems. Notably, marine heat waves are producing widespread coral bleaching events that are increasing in frequency, with projections for annual bleaching events on reefs worldwide by mid-century. C_LIO_LIThe response of corals to elevated seawater temperatures can be modulated by abiotic factors at site of origin and dominant endosymbiont type, which can result in a shift in multiple coral traits and drive physiological legacy effects that influence the trajectory of reef corals under subsequent thermal stress events. It is critical, therefore, to evaluate the potential for shifting physiological and cellular baselines driven by these factors in in situ bleaching (and recovery) events. Here, we use the back-to-back regional bleaching events of 2014 and 2015 in the Hawaiian Islands and subsequent recovery periods to test the hypothesis that coral multivariate trait space (here termed physiotype, sensu (Van Straalen, 2003) shift in multiple bleaching events, modulated by both environmental histories and symbiotic partnerships (Symbiodiniaceae). C_LIO_LIDespite fewer degree heating weeks in the first-bleaching event relative to the second (7 vs. 10), bleaching severity in a dominant reef building coral on Hawaiian reefs, Montipora capitata, was greater (~70% vs. 50% bleached cover) and differences due to environmental history (reef site) were more pronounced. Melanin, an immune cytotoxic response, provided an initial defense during the first event, potentially priming antioxidant activity, which peaked in the second-bleaching event (i.e., a legacy effect). While magnitude of bleaching differed, immune response patterns were shared among corals harboring heat-sensitive and heat-tolerant Symbiodiniaceae. This supports a pattern of increased constitutive immunity in corals resulting from repeat bleaching events, with greater specialized enzymes (catalase, peroxidase, superoxide dismutase) and attenuated melanin synthesis. C_LIO_LIThis study demonstrates bleaching events have implications for reef corals beyond shaping their ecological assemblages. These events can change the magnitude and/or identity of response variables contributing to physiotype, thus generating physiological legacies carried over into the future. Quantifying baseline coral physiotypes and tracking their shifts will be critical to understanding and forecasting the effects of increased bleaching frequency on coral biology and ecology in the Anthropocene. C_LI

ecology↗