Biology subjects

Sanchez-Alcaniz, J. A.

Publications and source records attributed to Sanchez-Alcaniz, J. A..

3 recordsLinked to original sources

bioRxiv2024

Molecular characterization of gustatory second-order neurons reveals integrative mechanisms of gustatory and metabolic information

Animals must balance the urgent need to find food during starvation with the critical necessity to avoid toxic substances to ensure their survival. In Drosophila, specialized Gustatory Receptors (GRs) expressed in Gustatory Receptor Neurons (GRNs) are critical for distinguishing between nutritious and potentially toxic food. GRNs project their axons from taste organs to the Subesophageal Zone (SEZ) in the Central Brain (CB) of Drosophila, where gustatory information is processed. Although the roles of GRs and GRNs are well-documented, the processing of gustatory information in the SEZ remains unclear. To better understand gustatory sensory processing and feeding decision-making, we molecularly characterized the first layer of gustatory interneurons, referred to as Gustatory Second-Order Neurons (G2Ns), which receive direct input from GRNs. Using trans-synaptic tracing with trans-Tango, cell sorting, and bulk RNAseq under fed and starved conditions, we discovered that G2Ns vary based on gustatory input and that their molecular profile changes with the flys metabolic state. Further data analysis has revealed that a pair of neurons in the SEZ, expressing the neuropeptide Leucokinin (SELK neurons), receive simultaneous input from GRNs sensing bitter (potentially toxic) and sweet (nutritious) information. Additionally, these neurons also receive inputs regarding the starvation levels of the fly. These results highlight a novel mechanism of feeding regulation and metabolic integration.

neuroscience↗

bioRxiv2023

Evolution of chemosensory tissues and cells across ecologically diverse Drosophilids

Chemosensory systems display exceptional variation between species, but little is known about how the evolution of gene expression and cell types contribute to this diversity. We have generated transcriptomes for five chemosensory tissues across six ecologically diverse Drosophila species and integrated their analyses with single-cell datasets to address these questions. The evolution of chemosensory transcriptomes has been predominantly shaped by stabilizing selection, but several thousand genes have nevertheless evolved expression changes in each tissue. Phylogenetic analyses of differentially expressed genes revealed strong evidence that their expression changes have been driven by a combination of cis-regulatory and cell composition evolution. We have also found that chemosensory-related gene families have undergone pervasive expression level changes and numerous species-specific expression gains/losses. Follow-up experiments revealed several chemoreceptors that evolved novel patterns of tissue and cellular expression that likely contribute to sensory differences. Finally, analyses of the genes that are differentially expressed between sexes uncovered extensive species-specific differences. Among these rapid changes, we discovered a D. melanogaster-specific excess of male-biased gene expression in its forelegs and identified sensory and muscle cells as the primary source of this dimorphism. Together, our analyses provide new insights for understanding evolutionary changes in ecologically key tissues at both global and individual gene levels.

evolutionary biology↗

bioRxiv2018

An expression atlas of chemosensory ionotropic glutamate receptors identifies a molecular basis of carbonation detection

Taste perception is thought to involve the encoding of appetitive and aversive chemical cues in food through a limited number of sensory pathways. Through expression analysis of the complete repertoire of Drosophila Ionotropic Receptors (IRs), a sensory subfamily of ionotropic glutamate receptors, we reveal that the majority of IRs is expressed in diverse peripheral neuron populations across gustatory organs in both larvae and adults, implying numerous roles in taste-evoked behaviours. We characterise Ir56d, which labels two anatomically-distinct classes of neurons in the proboscis: one represents a subset of sugar- and fatty acid-sensing neurons, while the other responds to carbonated solutions and fatty acids. Mutational analysis shows that IR56d, together with the broadly-expressed co-receptors IR25a and IR76b, is essential for physiological activation by carbonation and fatty acids, but not sucrose. We further demonstrate that carbonation is behaviourally attractive to flies (in an IR56d-dependent manner), but in a distinct way to other appetitive stimuli. Our work provides a valuable toolkit for investigating the taste functions of IRs, defines a molecular basis of carbonation sensing, and illustrates how the gustatory system uses combinatorial expression of sensory receptors in distinct neuron types to coordinate behaviour.

neuroscience↗