Biology subjects

Masi, A.

Publications and source records attributed to Masi, A..

3 recordsLinked to original sources

bioRxiv2026

From recognition to neglect: Molecular and physiological responses to heterospecific pollen decay with evolutionary distance

Post-mating, pre-zygotic (PMPZ) reproductive barriers are often attributed to precise molecular recognition between male and female gametes, yet little is known about how these interactions change as species diverge. In flowering plants, pollen tube growth depends on coordinated signaling between pollen and pistil, raising the question of whether PMPZ barriers arise through active incompatibility mechanisms or gradual loss of pollen-pistil coordination. Here, we combined transcriptomic profiling and pollen tube growth assays across a phylogenetically structured set of crosses in a diverse alpine plant community. We show that the magnitude of the pistillar transcriptomic response to pollination declined quantitatively with evolutionary distance rather than shifting in a binary compatible/incompatible manner. Pollination-associated functional gene ontology categories were strongest in conspecific and intrageneric crosses and weakened with divergence. Heterospecific pollen tubes also grew more slowly than conspecific tubes, with growth rates declining overall with genetic distance. However, the slowest growth occurred in intrageneric crosses, suggesting that close relatives may represent a distinct evolutionary zone where reduced maternal support coincides with additional hindrance mechanisms. Together, these results support a graded, divergence-dependent model of pollen-pistil incongruence driven primarily by attenuation of coordinated growth rather than strict heterospecific rejection.

evolutionary biology↗

bioRxiv2024

Optogenetic inhibition quenches the integration of sensory input in the cortex

SignificanceWe designed a novel all-optical tool to simultaneously silence neuronal activity at arbitrary sites on the dorsal cortex, and monitor the consequences of the manipulation. Optogenetic inhibition of primary sensory regions determined short and long-term dampening of the sensory response across a distributed cortical network. IntroductionMany fundamental processes of brain computation, such as sensory perception and motor control, heavily rely on the mesoscopic dynamics of activity across the cerebral cortex. Manipulating mesoscale activity and observing its effects across multiple brain regions is crucial for understanding the causal link between cortical dynamics and behavior. ObjectiveThe goal of this study was to develop a novel all-optical system that allows inhibition of excitatory neurons while simultaneously monitoring cortical responses at arbitrary sites across the entire dorsal cortex of mice. MethodsWe combined wide-field imaging and optogenetics to create a mesoscale all-optical approach, enabling simultaneous monitoring and manipulation of cortical activity using light. Intravenous injection of two PHP.eB AAVs enabled the whole-brain co-expression of the red-shifted calcium indicator jRCaMP1b and the inhibitory actuator stGtACR2, with stable expression over several weeks. This system was calibrated, and the effects of inhibition on sensory responses were tested. ResultsIncreasing laser power progressively reduced spontaneous activity at the site of irradiation. A single 5-second pulse on the barrel field cortex significantly decreased the amplitude of sensory-evoked responses, not only in the stimulated region but across the entire stimulated hemisphere. ConclusionsThis novel all-optical system enables targeted inhibition while concurrently monitoring mesoscale cortical activity. It provides insights into the dynamics of cortical circuits and offers a milestone for investigating the causal links between neuronal activity and behavior. Future research can use this tool to address sensory responsiveness impairments in neurological and neuropsychiatric disorders.

neuroscience↗

bioRxiv2024

Age-dependent cortical overconnectivity revers under anesthesia in Shank3 mice

Growing evidence points to brain network dysfunction as a central neurobiological basis for autism spectrum disorders (ASDs). As a result, studies on Functional Connectivity (FC) have become pivotal for understanding the large-scale network alterations associated with ASD. Despite ASD being a neurodevelopmental disorder, and FC being significantly influenced by the brain state, existing FC studies in mouse models predominantly focus on adult subjects under anesthesia. The differential impact of anesthesia and age on cortical functional networks in ASD subjects remains unexplored. To fill this gap, we conducted a longitudinal evaluation of FC across three brain states and three ages in the Shank3b mouse model of autism. We utilized wide-field calcium imaging to monitor cortical activity in Shank3b+/- and Shank3b+/+ mice fromlate development (P45) through adulthood (P90), and isoflurane anesthesia to manipulate the brain state. Our findings reveal that network hyperconnectivity, emerging from the barrel-field cortices during the juvenile stage, progressively expands to encompass the entire dorsal cortex in adult Shank3b+/- mice. Notably, the severity of FC imbalance is highly dependent on the brain state: network alterations are more pronounced in the awake state and shift towards hypoconnectivity under anesthesia. These results underscore the crucial role of anesthesia in detecting autism-related FC alterations and identify a significant network of early cortical dysfunction associated with autism. This network represents a potential target for non-invasive translational treatments.

neuroscience↗