116 research outputs found
Hydrology, Water Chemistry, and Vegetation Characteristics of a Tamarack Bog in Bath Township, Ohio: Towards Restoration and Enhancement
Author Institution: Dept. of Biology, University of Akron, OHAuthor Institution: Dept. of Botany, University of British Columbia, Vancouver, BC, CanadaAuthor Institution: Dept. of Natural Resource Science, Thompson Rivers University, Kamloops, BC, CanadaThe current state of the Bath Tamarack Bog has raised concern about the health and function of the system. Only 6 tamarack (Larix laricina) trees remain, while deciduous trees, particularly red maple (Acer rubrum) and invasive species such as glossy buckthorn (Rhamnus frangula) and multiflora rose (Rosa multiflora), dominate the bog. Our purpose was to assess the physical, chemical, and biological properties of the tamarack bog. Environmental and biological properties of Bath Tamarack Bog were measured from May 2001 through November 2002. In 2001, the center of the bog experienced water levels below those typically found in bogs, yet experienced normal water levels in the following year. Water chemistry results indicate the pH is much greater than that characteristic of a typical bog, ranging from 5.94 to 7.41. Nutrient levels fluctuated and were generally higher for calcium, potassium, and phosphate than a typical bog, while nitrogen levels remained low. These results indicate that the bog is not functioning normally and is in decline. The degradation of the bog is most likely due to anthropogenic activity. Ditching occurred between 1963 and 1969 and seems to have induced the progression of red maple trees and invasive species into the bog by lowering water levels. Since 1938, the first aerial photo we have record of, the bog has reduced to approximately a third of its size, which is approximately 1.99 hectares. The bog appears to be in a late successional stage, rapidly changing to a forested wetland. We discuss possible management and restoration efforts needed to restore or
enhance the tamarack bog, including 1) planting Sphagnum mats, 2) introducing tamarack seedlings, 3) controlling invasive species, and 4) maintaining the hydrology close to the soil surface. All of these
measures are suggested in association with educational outreach
Analysis of Diffusion of Ras2 in Saccharomyces cerevisiae Using Fluorescence Recovery after Photobleaching
Binding, lateral diffusion and exchange are fundamental dynamic processes
involved in protein association with cellular membranes. In this study, we
developed numerical simulations of lateral diffusion and exchange of
fluorophores in membranes with arbitrary bleach geometry and exchange of the
membrane localized fluorophore with the cytosol during Fluorescence Recovery
after Photobleaching (FRAP) experiments. The model simulations were used to
design FRAP experiments with varying bleach region sizes on plasma-membrane
localized wild type GFP-Ras2 with a dual lipid anchor and mutant GFP-Ras2C318S
with a single lipid anchor in live yeast cells to investigate diffusional
mobility and the presence of any exchange processes operating in the time scale
of our experiments. Model parameters estimated using data from FRAP experiments
with a 1 micron x 1 micron bleach region-of-interest (ROI) and a 0.5 micron x
0.5 micron bleach ROI showed that GFP-Ras2, single or dual lipid modified,
diffuses as single species with no evidence of exchange with a cytoplasmic
pool. This is the first report of Ras2 mobility in yeast plasma membrane. The
methods developed in this study are generally applicable for studying diffusion
and exchange of membrane associated fluorophores using FRAP on commercial
confocal laser scanning microscopes.Comment: Accepted for publication in Physical Biology (2010). 28 pages, 7
figures, 3 table
Multiexponential, multicompartmental, and noncompartmental modeling. I. Methodological limitations and physiological interpretations
Tracer kinetic model of blood-brain barrier transport of plasma protein-bound ligands. Empiric testing of the free hormone hypothesis.
Multiexponential, multicompartmental, and noncompartmental modeling. II. Data analysis and statistical considerations
Recommended from our members
13CO2 washout dynamics during intermittent exercise in children and adults.
To test the hypothesis that children store less CO2 than adults during exercise, we measured breath 13CO2 washout dynamics after oral bolus of [13C]bicarbonate in nine children [8 +/- 1 (SD) yr, 4 boys] and nine (28 +/- 6 yr, 5 males) adults. Gas exchange [O2 uptake and CO2 production (Vco2)] was measured breath by breath during rest and during light (80% of the anaerobic threshold) intermittent exercise. Breath samples were obtained for subsequent analysis of 13CO2 by isotope ratio mass spectrometry. The tracer estimate of Vco2 was highly correlated to Vco2 measured by gas exchange (r = 0.97, P < 0.0001). The mean residence time was shorter in children (50 +/- 5 min) compared with adults (69 +/- 7 min, P < 0.0001) at rest and during exercise (children, 35 +/- 7 min; adults, 50 +/- 11 min, P < 0.001). The estimate of stored CO2 (using mean Vco2 measured by gas exchange and mean residence time derived from tracer washout) was not statistically different at rest between children (254 +/- 36 ml/kg) and adults (232 +/- 37 ml/kg). During exercise, CO2 stores in the adults (304 +/- 46 ml/kg) were significantly increased over rest (P < 0.001), but there was no increase in children (mean exercise value, 254 +/- 38 ml/kg). These data support the hypothesis that CO2 distribution in response to exercise changes during the growth period
Splenic destruction of newly-formed red blood cells and shortened erythrocyte survival in mice with congenital microcytosis.
Test of models for replication of simian virus 40 DNA following ultraviolet irradiation.
When mammalian cells are irradiated with ultraviolet light, semiconservative DNA replication is inhibited and the length of newly synthesized daughter strands is reduced. We have used the simian virus 40 (SV40) viral system to examine the molecular mechanism by which this inhibition of DNA replication occurs immediately following ultraviolet irradiation. We tested two models for DNA replication-inhibition by using a procedure first developed by Danna, K. J., and D. Nathans (1972, Proc. Natl. Acad. Sci. USA, 69:3097-3100) in which the distribution of 3H-label in segments of newly completed SV40 form-I molecules is measured after short pulse labeling with 3H-thymidine. Our experimental results were compared with those predicted by mathematical models that describe two possible molecular mechanisms of replication inhibition. Our data are best fit by a "blockage" model in which any pyrimidine dimer encountered by the replication fork prevents complete replication of the SV40 genome. An alternative model called "slowdown" in which DNA damage causes a generalized slowdown of replication fork movement on all genomes has more adjustable parameters but does not fit the data as well as the blockage model
- …