45 research outputs found
Morphology and foliar chemistry of containerized Abies fraseri (Pursh) Poir. seedlings as affected by water availability and nutrition
• We present the results of a two-year (2007–2008) greenhouse study investigating the
effect of water availability and nitrogen fertilization on the growth, biomass
partitioning, and foliar nutrient content of Abies fraseri (Pursh)
Poir.
• Fertilizer and moisture content (irrigation) were varied in a factorial experiment
combining four levels of irrigation and three levels of fertilization to evaluate growth
and foliar nutrient content. In addition, a numerical optimization was used to estimate
appropriate levels of each factor necessary to achieve simulated goals for response
variables.
• Irrigation increased the height growth by 12 to 35% depending on the fertilization
treatment (p = 0.0001). Fertilization increased height growth by 10 to
26% (p = 0.02). A similar response was observed for stem diameter growth
(SDG). Total biomass accumulation increased as result of positive response of stem and
root biomass development, and foliar nitrogen content was positively affected by nitrogen
fertilization and negatively affected by irrigation. The numerical optimization for
simulated target growth and nitrogen content responses produced levels of input
combinations with high desirability factors to achieve the target responses.
• These results suggest that nutrient addition is a strong determining factor for early
development of this species. The improved growth efficiency in this study is likely
attributed to a combination of factors including, improved photosynthetic capacity,
decreased stomatal limitations, or increased resource allocation to stems
Genotoxic effect induced by hydrogen peroxide in human hepatoma cells using comet assay
Background: Hydrogen peroxide is a common reactive oxygen intermediate generated by variousforms of oxidative stress. Aims: The aim of this study was to investigate the DNA damage capacity ofH2O2 in HepG2 cells. Methods: Cells were treated with H2O2 at concentrations of 25 μM or 50 μM for5 min, 30 min, 40 min, 1 h or 24 h in parallel. The extent of DNA damage was assessed by the cometassay. Results: Compared to the control, DNA damage by 25 μM and 50 μM H2O2 increasedsignificantly with increasing incubation time up to 1 h, but it was not increased at 24 h. Conclusions:Our Findings confirm that H2O2 is a typical DNA damage inducing agent and thus is a good modelsystem to study the effects of oxidative stress. DNA damage in HepG2 cells increased significantlywith H2O2 concentration and time of incubation but later decreased likely due to DNA repairmechanisms and antioxidant enzyme