Biology subjects

Mariotti, L.

Publications and source records attributed to Mariotti, L..

3 recordsLinked to original sources

bioRxiv2026

A collicular somatostatinergic circuit gates sensory access to action

Animals are exposed to far more sensory information than can be converted into action and must prioritise behaviourally salient events. Although salience is commonly studied as modulation of sensory representations, stimulus prioritisation may also arise at premotor stages, through mechanisms that regulate the readiness of action-generating circuits to be recruited by sensory input. The superior colliculus links visual signals to spatially directed orienting and contains Pitx2-expressing spatial-motor modules that coordinate spatially targeted actions, providing a substrate for premotor regulation of sensory access to action. However, the circuit elements that regulate this access remain unknown. Here we identify an intersectionally targeted population of somatostatin-expressing inhibitory neurons in the mouse superior colliculus that is, at the population level, suppressed during orienting movements and visual stimulation. These neurons provide input to Pitx2-expressing spatial-motor modules, and their optogenetic silencing increased retinally evoked firing in Pitx2 neurons, showing that somatostatinergic inhibition constrains the visual recruitment of collicular motor output. Increasing somatostatinergic tone reduced interception of low- and intermediate-contrast visual targets while sparing responses to high-contrast targets, consistent with graded control of sensory access to action. Cholecystokinin-expressing inhibitory neurons and multiple cortical and subcortical regions provide anatomical input to the somatostatinergic population, identifying candidate routes for local and context-dependent regulation. Together, these findings establish somatostatinergic inhibition as a premotor control point that regulates the readiness of spatial-motor circuits for sensory recruitment and identify a circuit architecture through which the behavioural impact of salient sensory events could be regulated downstream of sensory encoding.

neuroscience↗

bioRxiv2025

The SAFE Labs Handbook: community-driven commitments for group leaders to improve lab culture

Creating positive and equitable lab environments has become a growing priority for the scientific community and funders of scientific research. Research institutions typically respond to this need by providing mandatory or optional training opportunities for their staff. However, there is no established resource for group leaders to improve their lab culture with concrete action points for implementation. Here, we introduce the SAFE Labs Handbook: a collection of thirty "commitments" which can be verifiably actioned without requiring institutional support. These commitments were collaboratively developed by thirteen group leaders in life sciences, from institutions across eight countries, instigated through the 2024 SAFE Labs workshop. The importance of each commitment has been scored by more than 200 researchers, at various career stages, from more than twenty countries. Even though all commitments were rated as significantly important by scientists from all career stages, implementation rates were notably low (< 25%). Lab members reported higher importance scores than group leaders, with large divergences indicating where group leaders may underestimate the potential impact on lab culture. Indeed, the overall implementation rate was correlated with importance score for group leaders, but not lab members. Strikingly, more than 95% of group leaders said they would consider implementing the handbook commitments. Given the high importance-scores and low-implementation rates, the SAFE Labs Handbook represents a unique, community-driven tool with significant potential to improve lab culture on a global scale.

scientific communication and education↗

bioRxiv2020

Nighttime gibberellin biosynthesis is influenced by fluctuating environmental conditions and contributes to growth adjustments of Arabidopsis leaves.

Optimal plant growth performance requires that the action of growth signals, such as gibberellins (GA), are coordinated with the availability of photo-assimilates. Here, we studied the links between gibberellin biosynthesis and carbon availability, and the subsequent effects on growth. The results presented here show that carbon availability, light and dark cues, and the clock ensure the timing and magnitude of gibberellin biosynthesis and that disruption of these mechanisms results in reduced gibberellin levels and expression of downstream genes. Carbon dependent nighttime induction of GIBBERELLIN 3-BETA-DIOXYGENASE 1 (GA3ox1) was severely hampered when preceded by a day of lowered light availability, leading specifically to reduced bioactive GA4 levels, and coinciding with a decline in leaf expansion rate during the night. We attribute this decline in leaf expansion mostly to reduced photo-assimilates. However, plants where gibberellin limitation was alleviated had significantly improved expansion demonstrating the relevance of gibberellins in growth control under varying carbon availability. Carbon dependent expression of upstream gibberellin biosynthesis genes (KAURENE SYNTHASE, KS and GIBBERELLIN 20 OXIDASE 1, GA20ox1) was not translated into metabolite changes within this short timeframe. We propose a model where the extent of nighttime biosynthesis of bioactive GA4 by GA3ox1 is determined by starch, as the nighttime carbon source, and so provides day-to-day adjustment of gibberellin responses.

plant biology↗