Spatial variability in tree-ring carbon isotope discrimination in response to local drought across the entire loblolly pine natural range.

Considering the temporal responses of carbon isotope discrimination (Δ13C) to local water availability in the spatial analysis of Δ13C is essential for evaluating the contribution of environmental and genetic facets of plant Δ13C. Using tree-ring Δ13C from years with contrasting water availability at 76 locations across the natural range of loblolly pine, we decomposed site-level Δ13C signals to maximum Δ13C in well-watered conditions (Δ13Cmax) and isotopic drought sensitivity (m) as a change in Δ13C per unit change of Palmer's Drought Severity Index (PDSI). Site water status, especially the tree lifetime average PDSI, was the primary factor affecting Δ13Cmax.

Ecosystem carbon density and allocation across a chronosequence of longleaf pine forests.

Forests can partially offset greenhouse gas emissions and contribute to climate change mitigation, mainly through increases in live biomass. We quantified carbon (C) density in 20 managed longleaf pine (Pinus palustris Mill.) forests ranging in age from 5 to 118 years located across the southeastern United States and estimated above- and belowground C trajectories.

Circulating fibrocytes stabilize blood vessels during angiogenesis in a paracrine manner.

Accumulating evidence supports that circulating fibrocytes play important roles in angiogenesis. However, the specific role of fibrocytes in angiogenesis and the underlying mechanisms remain unclear. In this study, we found that fibrocytes stabilized newly formed blood vessels in a mouse wound-healing model by inhibiting angiogenesis during the proliferative phase and inhibiting blood vessel regression during the remodeling phase.

Improved function and growth of pancreatic cells in a three-dimensional bioreactor environment.

Methods of three-dimensional (3D) cell culture have made significant progress in recent years due to a better understanding of cell to cell interactions and the cell's interface with their surrounding environment. We hypothesized that a microgravity 3D culture system would improve upon the growth and function of a pancreatic progenitor cell population. We developed a rotating wall vessel bioreactor and established a culture system using a pancreatic cell line.

MAPK/ERK and Wnt/β-Catenin pathways are synergistically involved in proliferation of Sca-1 positive hepatic progenitor cells.

Hepatic progenitor cells (HPCs) persist in adulthood and have the potential to play a major role in regenerating diseased liver. However, the signaling pathways that both directly and indirectly regulate HPCs' self-renewal and differentiation remain elusive. Previously, we identified a bipotent, stem cell antigen-1 (Sca-1) positive HPC population from naïve adult liver tissue.

Enrichment of a bipotent hepatic progenitor cell from naïve adult liver tissue.

Background/aim: Recent interest in the liver stem cell field has led to the identification and characterization of several hepatic progenitor cell populations from fetal and adult tissues. We isolated a hepatic progenitor cell from naïve adult liver and the current studies focus on differentiation and growth.

Results: A Sca-1(+) hepatic progenitor cell was identified within the liver parenchyma.

Influence of irrigation and fertilization on transpiration and hydraulic properties of Populus deltoides.

Long-term hydraulic acclimation to resource availability was explored in 3-year-old Populus deltoides Bartr. ex Marsh. clones by examining transpiration, leaf-specific hydraulic conductance (G(L)), canopy stomatal conductance (G(S)) and leaf to sapwood area ratio (A(L):A(S)) in response to irrigation (13 and 551 mm year(-1) in addition to ambient precipitation) and fertilization (0 and 120 kg N ha(-1) year(-1)).

Scaling ozone effects from seedlings to forest trees.

Biospheric ozone has become a widely distributed air pollutant, and a growing body of research indicates that ozone impacts forest health and productivity. Ozone effects are mediated by the ozone concentration present in the external environment and the movement of ozone into the leaf via the stoma. The cumulative dose received by the plant is, in the simplest terms, a function of ambient ozone concentration and stomatal conductance to water vapor.