Kakenov, S. | Search bioRxiv

bioRxiv2026

Rhythmic expression of a cAMP phosphodiesterase switches neuronal excitability states in the mammalian suprachiasmatic nucleus

How the transcriptome of a neuron determines its electrophysiological properties and how this change in different contexts are major questions in neurobiology. The intracellular molecular clocks in the circadian pacemaker neurons in the mammalian suprachiasmatic nucleus (SCN) drive 24hr rhythms in clock gene expression via a transcriptional-translational feedback loop1,2. These molecular clocks also control 24hr rhythms in the firing of SCN neurons3-5 - a subset of which enter a silent depolarized state around midday6. We used single-cell RNA sequencing and identified that the Avp / Nms and Vip / Nms are the SCN neurons that undergo daytime silencing. We also found high level and rhythmic expression of the Pde10a phosphodiesterase in these Nms SCN neurons. Acutely inhibiting Pde10a activity or elevating intracellular cAMP - to bypass high Pde10a levels - specifically shifts these Nms+ SCN neurons into a depolarized silent state hours ahead of schedule. A similar mechanism may occur in other neurons that switch to silent depolarized states.

neuroscience↗

bioRxiv2025

Diffuse and regionally structured domestication of the common fig (Ficus carica L.) in the Mediterranean Basin

Understanding domestication in perennial crops is crucial for unraveling the evolutionary trajectories that have shaped crop genetic diversity and for guiding future conservation and breeding efforts. The domestication of perennial Mediterranean fruit trees is less studied than that of annual crops. The common fig (Ficus carica L.) is thought to have been domesticated in the Levant before dispersion across the Mediterranean. However, pre-human fossils of F. carica in Europe suggest an ancient wild presence, challenging the assumption of a single eastern origin. We used microsatellite markers to genotype 949 fig accessions comprising cultivated and spontaneous individuals collected from 14 Mediterranean and Near Eastern countries representing F. carica sensu stricto and its two close relatives, F. carica subsp. rupestris, and, F. colchica. Principal component analysis revealed that F. carica sensu stricto forms a cohesive genetic group distinct from its two relatives, which are actually different species. Bayesian clustering revealed three major gene pools within F. carica sensu stricto -- Moroccan-Algerian, Northern Mediterranean, and Levantine--each containing both cultivated and spontaneous individuals. The Levantine group was the most differentiated, while the other two were closer genetically, together reflecting a longitudinal Mediterranean structure. Cultivated and spontaneous figs were genetically indistinguishable within each region, supporting a model of diffuse, regionally independent domestication rather than a single Levantine origin. These results highlight spontaneous populations and local landraces as key reservoirs of genetic variation, particularly in Morocco, Algeria, and the Levant. Our study provides a foundation for future genomic work to identify the genetic basis of key traits, emphasizing that practical breeding and conservation strategies should rely on regional biodiversity rather than a narrow set of elite cultivars to enhance fig resilience and productivity in the face of climate change and emerging disease pressures.

evolutionary biology↗