Project description:The identification of molecular specializations in cortical circuitry supporting complex behaviors, such as learned vocalizations, requires understanding the neuroanatomical context from which these circuits arise. In songbirds, the robust nucleus of the arcopallium (RA) provides the sole descending projection for fine motor control of vocalizations. Using single nuclei transcriptomics and spatial gene expression mapping in zebra finches, we were able to define cell types and molecular specializations that distinguish RA from adjacent regions involved in non-vocal motor and sensory processing. We describe an RA-specific vocal projection neuron, differential composition of inhibitory neuron subtypes, and unique glial specializations. We show how several cell-specific molecular features arise in a sex-dependent manner during development. Based on the molecular data, we were also able to electrophysiologically probe, for the first time, predicted GABAergic subtypes within RA. To facilitate future utilization of the data, we have developed interactive apps that allow integration of cell level molecular data with developmental and spatial distribution data from our gene expression brain atlas (ZEBrA). With this resource, users can explore molecular specializations of vocal-motor neurons and support cells that likely reflect adaptations key to the physiology and evolution of vocal control circuits.
Project description:The SNF1-related protein kinase 2 (SnRK2) pathway is a central regulator of abiotic stress signaling in land plants; however, its evolutionary origins and functional conservation across the green lineage remain poorly understood. Land plants evolved from streptophyte algae, whereas the chlorophyte algae, including the widely studied model Chlamydomonas reinhardtii, represent an older lineage that diverged from streptophytes over one billion years ago. Here, we identify and characterize a functional SnRK2 signaling module in Chlamydomonas reinhardtii. We show that the isoform SnRK2.7 is required for osmotic stress tolerance and general cellular viability, thus offering an alternative model for dissecting SnRK2 functions in algae. SnRK2.7 localizes to the contractile vacuole, an osmoregulatory organelle lost during streptophyte evolution, revealing a lineage-specific functional adaptation. Together with MAPKKK3, a B1/B3-RAF kinase, and the clade A protein phosphatase PP2C3, these components constitute a SnRK2 signaling module in Chlamydomonas reinhardtii. Our findings demonstrate the presence of a functional SnRK2 pathway in a chlorophyte alga, indicating that core components were established early in the green lineage. This work provides a foundation for comparative studies across green plants and underscores the need for broader taxonomic sampling to reconstruct the ancestral signaling networks underlying stress adaptation.
Project description:This study investigates the suitability of neochromosomes as orthogonal expression platforms for rewiring native cellular processes and implementing new functionalities.
Project description:14N/15N metabolic labeling was used to identify phosphorylation events and pathways affected by osmotic stress in green lineage plants
