Abstract Detail

Recent Topics Posters

El-Abdallah, Samar [1], Kammet, Ashley [2], Matsunaga, Kelly K.S. [3], Smith, Selena [4], Tomescu, Alexandru [5].

Comparing three methods for investigation of conifer woody seed cone anatomy.

Detailed data on seed cone anatomy are crucial for comparative studies with implications for conifer systematics and phylogeny.  In-depth understanding of comparative cone anatomy is also crucial for integrating anatomically-preserved fossils in such studies.  However, there are significant gaps in the available comparative data on cone anatomy in extant species, especially for the mature, woody and hardened cone stages.  This is because their hardness makes it difficult to obtain good sections of mature cones.  Here we compare three methods of producing sections of woody seed cones, applied to Taxodium distichum.  (1) Bioplastic wafers: dry cones or individual cone scales are embedded in bioplastic resin, then sectioned like rocks containing fossils, using petrographic methods and equipment (cut into thin wafers and ground to desired thickness).  Infiltration with epoxy resin under vacuum, of all surfaces cut open, is required to strengthen the tissues for grinding and polishing.  (2) Paraffin sectioning: classic method, employed on small cones or individual cone scales.  Material is fixed (FPA), dehydrated in ethanol, embedded in paraffin, sectioned on the rotary microtome, and stained as needed (e.g., Hematoxylin – Bismark Brown – Phloxine – Fast Green-Orange G).  Frequent cooling in ice bath and softening (using 5% fabric softener) are needed.  (3) μCT scanning: cones are scanned on an industrial X-ray micro-computed tomography system and analyzed using software for 3D rendering and virtual sectioning.  Paraffin sectioning, while providing high resolution and excellent details of anatomy and vascular architecture, can only be used for small specimens and is work-intensive for often sub-optimal quality of sections.  Bio-plastic sectioning is an easy, efficient process and can be used for larger specimens, but has low resolution, cannot be used for 3D renderings, and is limited to dry material with no fleshy tissue. µCT scanning requires little physical work, is fast, and can be used for large specimens with high resolution.  It also allows virtual sectioning in any plane and provides the only option to produce accurate 3D renderings.  However, tissue and cell type recognition requires comparisons with sections obtained by other methods.  Our comparison reveals that while the three methods each have advantages and drawbacks, they are complementary and could be combined to improve accuracy and efficiency of future studies.  An effective methodology could include initial mCT scanning to characterize the coarser morphology and anatomy, and to identify areas of interest, followed by targeted studies employing physical sectioning on selected parts of the cone.

1 - 1 Harpst street, Arcata, CA, 95521, USA
2 - Humboldt State University, Biological Sciences, 1 Harpst Street, Arcata, CA, 95521, USA
3 - University Of Michigan, Earth and Environmental Sciences, 1100 North University Avenue, Ann Arbor, MI, 48109, USA
4 - University Of Michigan, Department of Earth and Environmental Sciences, 1100 North University Avenue, 2534 CC Little Building, Ann Arbor, MI, 48109, USA
5 - Humboldt State University, Department Of Biological Sciences, 1 Harpst Street, Arcata, CA, 95521, USA

Keywords:
conifer
Taxodium
seed cone
Morphology
anatomy
method
sectioning
CT-scanning.

Presentation Type: Recent Topics Poster
Session: P, Recent Topics Posters
Location: Exhibit Hall/Omni Hotel
Date: Monday, June 26th, 2017
Time: 5:30 PM
Number: PRT012
Abstract ID:757
Candidate for Awards:None