Frederick Green

Adaptation of the Nelson-Somogyi Reducing-Sugar Assay to a Microassay Using Microtiter Plates

The Nelson-Somogyi assay for reducing sugars was adapted to microtiter plates. The primary advantages of this modified assay are (i) smaller sample and reagent volumes, (ii) elimination of boiling and filtration steps, (iii) automated measurement with a dual-wavelength scanning TLC densitometer, (iv) increased range and reproducibility, and (v) automated colorimetric readings by reflectance rather than absorbance.

Production of polygalacturonase and increase of longitudinal gas permeability in southern pine by brown-rot and white-rot fungi

Summary Hydrolysis of bordered and pinoid pits may be a key event during colonization of wood by decay fungi. Although pits are numerous, studies of pectin-hydrolyzing enzymes in wood decay fungi are scarce, probably because of the relatively low content (less than 4 %) of pectin in wood and because of the primary focus on understanding the degradation of lignified components. Endopolygalacturonase (endo- PG) activity was estimated by cup-plate assay and viscosity reduction of pectin from liquid cultures of fifteen brown-rot and eight white-rot basidiomycetous fungi using sodium polypectate as the carbon source. Oxalic acid was estimated in liquid culture and related to mycelial weight of each fungus. Changes in longitudinal gas permeability of southern pine cores exposed to selected decay fungi in liquid culture were measured to determine the extent of hydrolysis of bordered pits. Twelve of fifteen brown-rot and six of eight white-rot fungi tested were positive for at least one of the polygalacturonase test methods. Accumulation of oxalic acid was detected in thirteen of fifteen brown-rot isolates and none of the white-rot fungi tested. Gas permeability of pine cores increased approximately fourfold among brown-rot fungi tested and eighteenfold among white-rot fungi tested. Scanning electron microscopy revealed bordered pit membrane hydrolysis in cores colonized by white-rot fungi, but only torus damage, weakening and tearing of the pit membranes, was observed in cores exposed to brown-rot fungi. We conclude that both brown- and white-rot decay fungi have the enzymatic capacity to hydrolyze pectin, damage bordered pit membranes, and increase wood permeability during colonization and incipient decay.

A procedure for isolation and partial purification of guinea pig lung mast cells

Pulmonary mast cells were obtained from guinea pig lung using a combination of enzymatic digestion of tissue, centrifugal elutriation, and density gradient centrifugation on Percoll. In the initial procedure, lung tissue was enzymatically digested with collagenase and elastase in four 30 min incubations. Typically, monodispersed cell suspensions contained 4% mast cells. Further purification of these lung mast cells using elutriation and Percoll gradients consistently yielded mast cells of 40-78% (mean 51%) purity. These cells were morphologically intact, viable and found to be functional as determined by histamine release evoked by antigen and anti-guinea pig IgG1 antibody.

Carbohydrate-Degrading Complex of the Brown-Rot Fungus Postia placenta: Purification of β-1,4-Xylanase

An extremely stable extracellular glycoprotein, ß-l,4-xylanase, was isolated both by ethanol precipitation and by ultrafiltration from a crude, water-sotuble extract of sweetgum (Liquidambar styraciflua) decayed by the brown-rot fungus Postia placenta. The enzyme was funher purified and separated from the glycosidase enzymes on Fractogel 55. The molecular weight of the xylanase was estimated at 43,000 daltons by gel chromatography, SOS-PAGE, and HPLC. Activity of carboxymethylcellulase (ß-l,4-endoglucanase) enzyme comigrated electrophoretically with the xytanase. The apparent isoelectric focus point of the xylanase was estimated äs 3.8. The carbohydrate content of the xylanase ranged between 48% and 59% (w/w) depending upon the method of Isolation. The resistance of the xylanase fraction to denaturation or inactivation by SDS-2ME, urea, and guanidine-HCI is likely caused by the protective capacity of the high carbohydrate content of the glycoprotein.

Physical deterioration of preservative treated poles and pilings exposed to salt water

This report details the results of laboratory analyses of wooden pilings sent to the USDA Forest Products Laboratory in March 2011. These samples were removed from coastal wooden posts, poles, piles, and deck boards. A total of 22 samples, consisting of either core borings or surface fiber samples, were removed from four installations along the South Carolina coast. Methods focusing on the physical, chemical, and biological properties of the wood determined that the 22 specimen samples consisting of core borings and surface fiber samples were physically deteriorated by salt accumulation and not biological deterioration. This report presents the findings of these analyses and discusses the cause of the documented damage.