Can We Visually Inspect the Needles of Fraser Fir to Estimate an Indicator of Shoot Health?
Abies fraseri (Fraser fir) is the dominant tree species in the high elevation forests of the Southern Appalachian mountains. The future of A. fraseri populations remains uncertain; the species is showing signs of decline in health and increased mortality throughout its range. Current physiological assessments require expensive and bulky equipment; the ability to quickly assess shoot function using a visual inspection could be a useful tool in projects where a health category would be sufficient.
Needles from A. fraseri were collected from five mountaintops in the Great Smoky Mountain National Park, representing most of its native range. Maximum photosynthetic rate, an important measure of leaf function, was measured in the field using a LICOR infrared gas analyzer. In the lab, needles were imaged using a flat-bed scanner and measured using MIMSI, a computer program for measuring the area, length, and width of individual needles. A visual inspection of shoots was also performed, wherein each shoot was scored by color, needle density, and necrosis, and categorized as Normal, Skinny, Blunted, or Dying. We were surprised to find that neither needle morphology nor visual characters predict maximum photosynthetic rate. Indeed, even dying shoots had similar maximum photosynthetic rate to normal needles. Therefore a visual inspection is not sufficient for assessing shoot health.
1 Dept of Ecology and Evolutionary Biology 2 Dept of Forestry: University of Tennessee, Knoxville, TN.
P187 • Susan Jones - Held1, Michael Held2
Early Growth of Thellungiella Salsuginea (Ecotype Yukon) in Response to Excess Iron
Thellungiella salsuginea (salt cress) is tolerant to abiotic stresses such as drought, cold and salinity unlike its glycophyte relative, Arabidopsis thaliana. Due to its tolerance to these stresses we were interested in examining the effects of altering iron levels on early growth of Thellungiella. The Yukon ecotype of this species grows on alkaline soil. The solubility of iron can be limiting on alkaline soils. Salt cress seedlings had reduced root growth when grown on half-strength MS macronutrients supplemented with excess iron [100 µM Fe+2 or Fe+3] although the reduction in root growth was more pronounced with Fe+2. Similarly, Arabidopsis exhibited reductions in root growth at these Fe concentrations, but not to the same extent as salt cress. In contrast to Arabidopsis, salt cress seedlings accumulated less Fe. The source of Fe did have an effect on the extent of Fe accumulation in both species. When Fe was supplied as Fe+2, total Fe was greater than in seedlings treated with Fe+3. Also, the patterns in extracellular pH changes in response to the different Fe sources were different between Thellungiella and Arabidopsis. These differences will be discussed in relation to iron acquisition and metabolism.
1 Dept of Plant Biology and Biology, Rutgers University, New Brunswick, NJ; 2 Dept of Biology, Saint Peter’s University, Jersey City, NJ
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P188 • Charles P. Fyfe II, Eric M. Benfield, Kristy Y. Johnson
Stress has often been referred to as the silent killer’ of humans. Over long periods of time, stress can increase the chance of heart disease, high blood pressure, and irregular heartbeat. In part, these negative health effects can be attributed to the physiological effect of prolonged exposure to high levels of cortisol, a steroidal hormone that increases rapidly in the bloodstream in response to both acute and chronic stress. While transient elevations of cortisol in the blood have been studied extensively, it has only recently been shown that cortisol deposited in growing hair is an accurate reflection of a systemic concentration over a long period of time. We are conducting our study at The Citadel, a military college known for its rigorous regimented lifestyle and stressful fourth-class system for freshman cadets. We have collected hair samples from a mean sample size of 16 freshman cadets before they matriculated at The Citadel and have continued to collect weekly hair samples, along with a corresponding weekly questionnaire detailing their weekly cadet activities, academic activities, and perceived weekly stress. We are using an extraction protocol and enzyme-linked immunoassays to measure the cortisol levels from each sample. We will then analyze the data and search for long-term correlations between the cortisol concentrations before and after matriculation, along with the details of the questionnaires. In our analysis, we will consider the fourth-class system as a chronic stressor and weekly events as acute stressors.
Dept of Biology, The Citadel, Charleston, SC
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P189 • Julia Oakley, Claudia M. Williams
Measuring Changes in Blood Vessel Diameter in the Tail of the Goldfish (Carassius auratus)
Blood flow to tissues can be regulated by dilation and constriction of vessels, and these changes in vessel diameter may be caused by localized or systemic factors. Previous studies on the observations of vasodilation and vasoconstriction of blood vessels are common, however most research does not show changes as specific measurements of vessel diameter. This study measured changes in the diameter of arterioles and venules in the tail of the Goldfish, Carassius auratus, using microscopy and Imagej software. Localized changes were caused by variations in temperature, with heat causing an increase in vessel diameter and cold causing a decrease in vessel diameter. Systemic changes were caused by epinephrine or acetylcholine transported through the gills into the bloodstream. Preliminary measurements show that epinephrine increased vessel diameter and acetylcholine decreased vessel diameter. This study is a model for future studies focusing on measuring quantitative changes caused by chemicals in freshwater habitats.
Campbell University, Buies Creek, NC
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P190 • Taylor E. Spillman1, Finn B. Fürstenwerth1, Duncan D. Cameron2, Jay F. Bolin1
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