Fig. 2: Monoaminergic neurons in spider brains.
From: Single-cell transcriptomics reveals the brain evolution of web-building spiders
a, Re-clustering of monoaminergic neurons. b, Biosynthesis of serotonin from tryptophan and biosynthesis of tyramine, octopamine, dopamine and norepinephrine from tyrosine. c, Expression of enzymes that synthesize monoamine neurotransmitters. Six monoaminergic sub-clusters were identified, representing dopaminergic (cluster 3), tyraminergic (cluster 11), octopaminergic (clusters 0 and 8), serotonergic (cluster 12) and noradrenergic neurons (cluster 10). Colours represent the average expression level of a gene and dot sizes represent percentages of cells within each cluster expressing that gene. d, Expression pattern of genes that involved in synthesis of dopamine (Th and Ddc, red circle) and norepinephrine (Th, Ddc and Dbh, green circle). e, Norepinephrine (n = 7 for Hylyphantes, 4 for Drosophila) and octopamine level (n = 8 for Hylyphantes, 4 for Drosophila) in Hylyphantes and Drosophila head, measured by high-performance liquid chromatography (HPLC). Each dot represents the value of a biological replicate. Bars are mean ± standard deviation (SD) across replicates. f, Norepinephrine was detected by HPLC. The retention time of Hylyphantes, Drosophila and standard norepinephrine was present. mAU, milli-absorbance units. g, Anti-synapsin (SYNORF1, magenta) and anti-norepinephrine (green) showed the cell bodies (arrow) of noradrenergic neurons were distributed above the central body (CB) of the spider brain. Four biological replicates were performed to confirm the distribution of norepinephrine neurons. Please see the major brain structure of spider in Extended Data Fig. 3. h, Expression of representative adrenoceptors and octopamine receptors across different cells in the spider brain. i, Expression of representative monoaminergic receptors across different tissues in the spider (n = 3 for brain, 11 for legs, 3 for silk glands and 3 for venom glands). One octopamine receptor (Octbeta2R-2) was highly expressed in the brain and legs, and one adrenergic receptor (ADRB1) was highly expressed in peripheral tissues. Statistical comparisons were performed by Kruskal Wallis test followed by post-hoc Dunn’s correction. H is the test statistic for the Kruskal Wallis test and df is freedom degrees. Data in bar plots are mean ± SD.
