Halbrook, Kandres , Smith, Steven , Holbrook, Billie M. , Espiriti , Alva .
Comparison of polyvinylsiloxane impression material for use in SEM plant macrofossil analyses.
Scanning electron microscopy (SEM) is an excellent tool to study surface features of permineralized and soft tissue plant macrofossils. SEM can image bulk objects at resolutions less than 1 um, which allows for detailed qualitative and quantitative observations of epidermal cells, stomatal complexes, trichomes, papillae, and other features for use in comparative anatomy, classification, and paleoclimatic and ecological interpretations. However, directly viewing biological material in SEM may damage the specimen, even when samples are gold coated in standard SEM or uncoated in variable-pressure SEM. Moreover, coatings are irreversible and most fossils are too valuable to risk permanent alteration. Here, we test a method using polyvinylsiloxane (PVS), a high-resolution dental impression material, for use in making negative impressions of soft tissue macrofossils of Bouteloua curtipendula (Poaceae) recovered from packrat middens. PVS has been used successfully to make serial impressions of living epidermal cells in Pisum and Arabidopsis. We compared four PVS formulations for their SEM image resolution, structural stability, reproducibility, specimen recoverability, and residue left on the specimen. We also tested the SEM image resolution of epoxy resins and polymers used to make positive replicas from the PVS impressions and considered the efficacy of analyzing negative impressions versus positive replicas directly in SEM.
Log in to add this item to your schedule
1 - University of Arizona, School of Natural Resources, 325 Biological Sciences East, Tucson, Arizona, 85721, USA
2 - B.M. Holbrook Dentistry, 5725 E 5th St , Tucson, AZ, 85711
Presentation Type: Poster:Posters for BSA Sections
Location: Event Tent/Cliff Lodge
Date: Tuesday, July 28th, 2009
Time: 5:30 PM