With over 48,000 species currently described, spiders (Arthropoda: Chelicerata: Araneae) comprise one of the most diverse groups of animals on our planet, and exhibit an equally wide array of fascinating behaviors. Studies of central nervous systems (CNSs) in spiders, however, are relatively sparse, and no reports have yet characterized catecholaminergic (dopamine [DA]- or norepinephrine-synthesizing) neurons in any spider species. Because these neuromodulators are especially important for sensory and motor processing across animal taxa, we embarked on a study to identify catecholaminergic neurons in the CNS of the wolf spider Hogna lenta (Lycosidae) and the jumping spider Phidippus regius (Salticidae). These neurons were most effectively labeled with an antiserum raised against tyrosine hydroxylase (TH), the rate-limiting enzyme in catecholamine synthesis. We found extensive catecholamine-rich neuronal fibers in the first- and second-order optic neuropils of the supraesophageal mass (brain), as well as in the arcuate body, a region of the brain thought to receive visual input and which may be involved in higher order sensorimotor integration. This structure likely shares evolutionary origins with the DA-enriched central complex of the Mandibulata. In the subesophageal mass, we detected an extensive filigree of TH-immunoreactive (TH-ir) arborizations in the appendage neuromeres, as well as three prominent plurisegmental fiber tracts. A vast abundance of TH-ir somata were located in the opisthosomal neuromeres, the largest of which appeared to project to the brain and decorate the appendage neuromeres. Our study underscores the important roles that the catecholamines likely play in modulating spider vision, higher order sensorimotor processing, and motor patterning.
Bibliographical noteFunding Information:
We thank the members of the Mesce laboratory, especially our dedicated animal care specialists who helped to maintain our spider collection during these experiments: Melody Aiello, Lia Chin-Purcell, Kevin Cunningham, Zo? Harvey, Jessica Jacobson, Glacel Lopez, Taylor Pitel, Terra Plum, Anthony Polyakov, Jessica Rydeen, and Earl Wilson. Staff at the University of Minnesota Imaging Center assisted with the confocal microscopy, in particular Grant Barthel, John Oja, Guillermo Marqu?s, and Mark Sanders. Colleen Forster assisted with the preparation of tissue sections at the UMN BLS Histology Laboratory. Skye Long (University of Massachusetts, Amherst) provided helpful consultation on the spider neuroanatomy. This work was funded by a grant from the USDA National Institute of Food and Agriculture, Hatch Project 1013093 awarded to K. A. Mesce, and an OSF CFANS Fellowship, Thomas H. Shevlin Fellowship, Marion-Brooks Wallace Fellowship, and UMN Doctoral Dissertation Fellowship to A. Auletta.
© 2019 Wiley Periodicals, Inc.
- arcuate body
- optic neuropil
- tyrosine hydroxylase