A5022424095- Polyamine Metabolism and Applications
- Plant Stress Responses and Tolerance
- Plant tissue culture and regeneration
- GABA and Rice Research
- Aluminum toxicity and tolerance in plants and animals
- Forest ecology and management
- Plant responses to elevated CO2
- Plant Water Relations and Carbon Dynamics
- Soil Carbon and Nitrogen Dynamics
- Legume Nitrogen Fixing Symbiosis
- Tree-ring climate responses
- Plant nutrient uptake and metabolism
- Plant Molecular Biology Research
- Forest Insect Ecology and Management
- Amino Acid Enzymes and Metabolism
- Plant and Fungal Interactions Research
- Plant Surface Properties and Treatments
- Arsenic contamination and mitigation
- Plant Reproductive Biology
- Lichen and fungal ecology
- Tree Root and Stability Studies
- Microbial Community Ecology and Physiology
- Botany and Plant Ecology Studies
- Wood Treatment and Properties
- Selenium in Biological Systems
Northern Research Station
2015-2024
US Forest Service
2010-2024
United States Department of Agriculture
2002-2022
Durham Technical Community College
2020
University of New Hampshire
1984-2009
Eastern University
2005
Durham University
2004
The metabolism of glutamate into ornithine, arginine, proline, and polyamines is a major network nitrogen-metabolizing pathways in plants, which also produces intermediates like nitric oxide, γ-aminobutyric acid (GABA) that play critical roles plant development stress. While the accumulations products this depend primarily on nitrogen assimilation, overall regulation interacting sub-pathways not well understood. We tested hypothesis diversion ornithine polyamine biosynthesis (by transgenic...
Watershed budget studies at the Hubbard Brook Experimental Forest (HBEF), New Hampshire, USA, have demonstrated high calcium depletion of soil during 20th century due, in part, to acid deposition. Over past 25 years, tree growth (especially for sugar maple) has declined on experimental watersheds HBEF. In October 1999, 0.85 Mg Ca/ha was added 1 (W1) HBEF form wollastonite (CaSiO3), a treatment that, by summer 2002, had raised pH Oie horizon from 3.8 5.0 and, Oa horizon, 3.9 4.2. We measured...
Despite the availability of several protocols for extraction chlorophylls and carotenoids from foliage forest trees, information regarding their respective efficiencies is scarce. We compared acetone, ethanol, dimethyl sulfoxide (DMSO), N, N-dimethylformamide (DMF) over a range incubation times using small amounts unmacerated tissue. Of 11 species studied, comparable chlorophyll were extracted by all four solvents three ethanol DMF nine species. In species, amounts, while in another two...
At the Harvard Forest, Petersham, MA, impact of 20 years annual ammonium nitrate application to mixed hardwood stand on soil bacterial communities was studied using 16S rRNA genes pyrosequencing. Amplification done DNA extracted from 30 samples (three treatments × two horizons five subplots) collected untreated (control), low N-amended (50 kg ha(-1) year(-1)) and high (150 plots. A total 1.3 million sequences were processed qiime. Although Acidobacteria represented most abundant phylum based...
We overexpressed a mouse ornithine decarboxylase gene under the control of constitutive and an estradiol-inducible promoter in Arabidopsis thaliana to increase our understanding regulation polyamine metabolism. Of particular interest was role substrate not only biosynthesis, but also accumulation related amino acids response short-term induction this enzyme. hypothesized that inducible expression transgene would mimic natural responses plants changing conditions, e.g. stress conditions...
Rates of nitrogen (N) deposition are increasing in industrialized and rapidly developing nations. Simulated N suppresses plant litter decay rates, particular for low quality (high lignin) litter. Litter is a primary driver decomposition; however, it not clear how changes caused by long‐term ecosystem exposure to chronic additions interact with altered soil N‐availability influence dynamics. To document the effects simulated on quality, we conducted meta‐analysis available nutrient data from...
Silver nanoparticles (Ag NPs) are widely used in consumer products, and their release has raised serious concerns about the risk of exposure to environment human health. However, biochemical mechanisms by which plants counteract NP toxicity largely unknown. We have previously engineered Crambe abyssinica expressing bacterial γ-glutamylecysteine synthase (γ-ECS) for enhancing glutathione (GSH) levels. In this study, we investigated if enhanced levels GSH its derivatives can protect from Ag...
Abstract The metabolism of polyamines (putrescine, spermidine, and spermine) has become the target genetic manipulation because their significance in plant development possibly stress tolerance. We studied polyamine non-transgenic (NT) transgenic cells poplar (Populus nigra ×maximowiczii) expressing a mouse Orn decarboxylase (odc) cDNA. showed elevated levels ODC enzyme activity, severalfold higher amounts putrescine, small increase reduction spermine as compared with NT cells. conversion...
The mechanisms that control polyamine (PA) metabolism in plant cell lines with different embryogenic potential are not well understood. This study involved the use of two Araucaria angustifolia lines, one which was defined as being blocked, cells were incapable developing somatic embryos, and other responsive, could generate embryos. Cellular PA modulated by using 5 mM arginine (Arg) or ornithine (Orn) at time points during growth. Two days after subculturing Arg, an increase citrulline...
Polyamines (PAs) are ubiquitous polycations found in plants and other organisms that essential for growth, development, resistance against abiotic biotic stresses. The role of PAs plant disease depends on the relative abundance higher [spermidine (Spd), spermine (Spm)] vs. diamine putrescine (Put) PA catabolism. With respect to pathogen, required achieve successful pathogenesis host. Maize is an important food feed crop, which highly susceptible Aspergillus flavus infection. Upon infection,...
Changes in the cellular content of three polyamines (putrescine, spermidine and spermine) were compared at different stages development zygotic somatic embryos Pinus radiata D. Don . During embryo development, both showed a steady increase content, with either small decrease or no significant change putrescine. This led to several‐fold spermidine/putrescine ratios during types embryos. Cell cultures plant‐forming non‐plant‐forming lines derived from same clone growing on proliferation...
Dendrochemical and biochemical markers link stress in apparently healthy red spruce trees (Picea rubens) to acidic deposition. Acidic deposition forests of the northeastern USA increased sharply during 1960s. Previous reports related visible damage at high elevations root soil processes. In this report, dendrochemical foliar indicate perturbations biological processes across USA. research on dendrochemistry stemwood indicated that under uniform environmental conditions, concentrations Ca Mg...
Abstract We investigated the catabolism of putrescine (Put) in a non-transgenic (NT) and transgenic cell line poplar (Populus nigra × maximowiczii) expressing mouse (Mus musculus) ornithine (Orn) decarboxylase (odc) cDNA. The cells produce 3- to 4-fold higher amounts Put than NT cells. rate loss from initial half-life cellular were determined by feeding with [U-14C]Orn [1,4-14C]Put as precursors following [14C]Put at various times after transfer label-free medium. amount converted into...
A study established in 1985 north-central Pennsylvania to determine effects of lime fertilization on declining sugar maple (Acer saccharum Marsh.) was evaluated 1993 and showed that liming positively affected growth crown vitality maple. This effect offered an opportunity assess other indicators tree their response additions. Foliar polyamines, starch soluble sugars root tissues, cambial electrical resistance (CER) at breast height were evaluated. putrescine, sugars, CER decreased, while...