Collaborative Research: Genetics and biomechanics of non-Newtonian prey capture adhesives across Panarthropoda

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Several groups of invertebrate species produce prey capture glues that are deposited on silks, secreted onto limbs, or squirted directly onto prey. These glues are materially unique in their drying times and reaction to humidity, but they are functionally similar in that they vary in viscosity based on applied forces and their rapid adhesion. The researchers will investigate the molecular and physical attributes of prey capture glues from 10 species in three distantly related groups - arachnids (spiders and opilionids), flies (predatory glow worms), and onychophorans (velvet worms). By understanding the differences in glue properties with respect to their molecular bases, a catalog of necessary components can be established for the design of new synthetic adhesives. This research will furthermore enhance participation of underrepresented minorities in field coursework, which research continues to demonstrate to be critically important to individuals choosing careers in ecology, evolution, and environmental sciences. The Highlands Biological Station (HBS) in Highlands, North Carolina, is an important resource for research in the Appalachian region and has hosted the two-week field class, “The Biology of Spiders,” for several decades. This class focuses on field identification, specimen collection, and preservation. With the twin goals of furthering positive public perception and interest in arachnids within the Appalachian region, and improving access to fieldwork opportunities for diverse student populations, the researchers will enhance the existing course by supporting student attendance via diversity-focused scholarships, new course material, and contributions to the HBS arachnid collection through student participation.Unlike materials with homologous origin that diversify under selective pressure, investigating convergently evolved prey capture glues from distantly related organisms offers a unique opportunity to explore the necessary and novel components for constructing these adhesives. This project will examine prey capture glues with the broad goals of understanding the contribution of their molecular components to function, and discovering the commonalities associated with functional, ecological, or morphological similarity. First, targeted transcriptomics, DNA sequencing, and glycosylation analyses will be employed to reconstruct the biomolecular organization of the glue from each species. This will be the first study to investigate the importance of glue gene length and repetitiveness for glue function, and the first comparison of posttranslational O-glycosylation modifications in a diversity of bioadhesives. Second, force transduction measurements during adhesive manipulation will allow documentation and analysis of the biomechanical properties of each glue. Combined with full-length sequences, direct inference will be made about the mechanical potential of glue sequence, including the role of repeat number and unit complexity in contributing to adhesive toughness and extensibility. Finally, we will reconstruct gene trees in order to evaluate support for parallel or convergent evolution of prey capture adhesives. Similar sequence identity will support the convergent strength of functional selection in the evolution of prey capture glue genes. Alternatively, poor sequence identity between glue transcripts indicates that a variety of biochemical mechanisms exist for prey adhesion, providing exciting novel pathways for biomimetic synthesis.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.