Browsing by Author "Goodell, Barry"

Premise of the study: Coniferous bordered pits are some of the most unique and fascinating microstructures of the lignified cell wall. The pit membrane consists of a margo and a torus region, hence facilitating both xylary water transport and also limiting air intrusion by pit aspiration. Additionally, bordered pits have been reported to play a decisive role in the control of rapid liquid flow via the shrinkage and swelling of pectin. The study of the nanostructural chemical composition of pit membranes has been difficult with common imaging/chemical techniques, which involve drying and/or coating of the samples. Methods: Using fluorescent tagging and antibodies specific to pectin, and a His-tagged cellulose-binding module that reacts with crystalline cellulose, in combination with confocal laser scanning microscopy (CLSM) and 4Pi microscopy, we generated three-dimensional images of intact pit membranes. Key results: With enhanced resolution in the z-direction of the 4Pi microscope, it was possible to distinguish cellulose in the torus and the margo strands of Pinus strobus. The torus was surrounded by pectin, and a pectin ring was found at the margin of the torus. We also found differences in the structure of the pit membrane between aspirated and unaspirated pits, with a displacement of pectin to form a ring-like structure, the collapse of a void in the interior of the torus, and an apparent change in the chemical structure of cellulosic components, during the aspiration process. Conclusions: The 4Pi microscope is well suited to scanning pit membranes to discover previously undescribed anatomical features in bordered pits and can provide information on chemical composition when used in combination with appropriate probes.

The mechanical properties of phenolic resin reinforced with three different carbon materials were investigated experimentally. The carbon materials: (1) commercially produced carbon nanotubes (CNTs), (2) flash-heated lignocellulose containing CNTs and carbon-black, and (3) cyclically oxidized lignocellulose (Goodell, B. et al. (2008). Journal of Nanoscience and Nanotechnology, 8: 2472-2474) were added to phenolic resin in different weight percentages to fabricate composites. Carbon nanotubes were found to be an effective reinforcing filler increasing tensile strength by 45.34% and Young's modulus by 19.08% with a 2% loading. The flash-heated material increased Young's modulus by 11.04% with a 2% loading but did not affect tensile strength. The cyclically heated material did not contain CNTs, their inclusion in the composites reduced Young's modulus and, for the 1% loading, reduced tensile strength as well.

Pine wood (Pinus sylvestris) veneer strips were incubated in acetate buffer containing hydrogen peroxide and Fe ions (Fenton's reagent) to mimic aspects of brown rot decay and to assess the degradation of cellulose in wood via measurement of tensile properties (measured in a zero-span mode). Varying the type of iron (ferrous or ferric sulfate) mixed with H(2)O(2) did not yield significant differences in the rates of H(2)O(2) concentration and tensile strength reduction. However, increasing the amount of wood material (the number of wood strips) in the reaction mixture elevated Fe(III) reduction in solution, indicating that wood constituents participated in this reaction. Increasing concentrations of Fe(III) in the reaction mixture resulted in a decrease in H(2)O(2) in solution. Despite an increase in iron concentration and H(2)O(2) decomposition under these conditions, a uniform and consistent strength loss of 30% was observed at all Fe(III) concentrations tested. At fixed Fe(III) concentrations, increasing the H(2)O(2) concentration linearly increased the strength loss of the veneers up to approximately 50% within 24 h. The addition of a low molecular weight, metal-binding, phenolic compound (2,3-dihydroxybenzoic acid) and of a non-chelating hydroquinone to the reaction mixtures entailed a more rapid consumption of H(2)O(2); however, the tensile strength loss of the veneers decreased with increasing concentration of the phenolics. Thus, in contrast to previous studies on cellulose degradation, phenolics reduced the degree of wood decay in a Fenton system.

Brown rot decay removes cellulose and hemicellulose from wood-residual lignin contributing up to 30% of forest soil carbon-and is derived from an ancestral white rot saprotrophy in which both lignin and cellulose are decomposed. Comparative and functional genomics of the "dry rot" fungus Serpula lacrymans, derived from forest ancestors, demonstrated that the evolution of both ectomycorrhizal biotrophy and brown rot saprotrophy were accompanied by reductions and losses in specific protein families, suggesting adaptation to an intercellular interaction with plant tissue. Transcriptome and proteome analysis also identified differences in wood decomposition in S. lacrymans relative to the brown rot Postia placenta. Furthermore, fungal nutritional mode diversification suggests that the boreal forest biome originated via genetic coevolution of above- and below-ground biota.