High Precision X-ray CT-scanning of Biological Samples

Visualizing the micro-scale details of an item without disturbing its natural structure is always desirable because critical information is often lost during dissection or destructive analysis. High precision X-ray CT scans are used in engineering analyses to non-destructively view samples with volume elements as small as 10micro-meters, but this technique is problematic for non-rigid biological samples. Other problems arise from low x-ray contrast of tissue and the long scan times required. We will present results of micro-CT scans performed on biological samples as small as a bovine embryo and as large at a coyote skull. We will also discuss techniques to enhance the details captured in the x-ray images using contrast enhancers such as iodine (stains). We are working on post scan techniques to improve image quality, reduce scan times and to isolate items appearing in CT scans so they can be accurately recreated using a 3-D printer. Results and progress will be reported

Regional and scale-specific effects of land use on amphibian diversity [poster]

Background/Question/Methods Habitat loss and degradation influence amphibian distributions and are important drivers of population declines. Our previous research demonstrated that road disturbance, development and wetland area consistently influence amphibian richness across regions of the U.S. Here, we examined the relative importance of these factors in different regions and at multiple spatial scales. Understanding the scales at which habitat disturbance may be affecting amphibian distributions is important for conservation planning. Specifically, we asked: 1) Over what spatial scales do distinct landscape features affect amphibian richness? and 2) Do road types (non-rural and rural) have similar effects on amphibian richness? This is the second year of a collaborative, nationwide project involving 11 U.S. colleges integrated within undergraduate biology curricula. We summarized North American Amphibian Monitoring Program data in 13 Eastern and Central U.S states and used geographic information systems to extract landscape data for 471 survey locations. We developed models to quantify the influence of landscape variables on amphibian species richness and site occupancy across five concentric buffers ranging from 300m to 10,000m. Results/Conclusions Across spatial scales, development, road density and agriculture were the best predictors of amphibian richness and site occupancy by individual species. Across regions, we found that scale did not exert a large influence on how landscape features influenced amphibian richness as effects were largely comparable across buffers. However, development and percent impervious surface had stronger influence on richness at smaller spatial scales. Richness was lower at survey locations with higher densities of non-rural and rural roads, and non-rural road density had a larger negative effect at smaller scales. Within regions, landscape features driving patterns of species richness varied. The scales at which these factors were associated with richness were highly variable within regions, suggesting the scale effects may be region specific. Our project demonstrates that networks of undergraduate students can collaborate to compile and analyze large ecological data sets, while engaging students in authentic and inquiry-based learning in landscape-scale ecology

The consolidation of implicit sequence memory in obstructive sleep apnea

Obstructive Sleep Apnea (OSA) Syndrome is a relatively frequent sleep disorder characterized by disrupted sleep patterns. It is a well-established fact that sleep has beneficial effect on memory consolidation by enhancing neural plasticity. Implicit sequence learning is a prominent component of skill learning. However, the formation and consolidation of this fundamental learning mechanism remains poorly understood in OSA. In the present study we examined the consolidation of different aspects of implicit sequence learning in patients with OSA. We used the Alternating Serial Reaction Time task to measure general skill learning and sequence-specific learning. There were two sessions: a learning phase and a testing phase, separated by a 10-hour offline period with sleep. Our data showed differences in offline changes of general skill learning between the OSA and control group. The control group demonstrated offline improvement from evening to morning, while the OSA group did not. In contrast, we did not observe differences between the groups in offline changes in sequence-specific learning. Our findings suggest that disrupted sleep in OSA differently affects neural circuits involved in the consolidation of sequence learning

High Precision X-ray CT-scanning of Biological Samples

Visualizing the micro-scale details of an item without disturbing its natural structure is always desirable because critical information is often lost during dissection or destructive analysis. High precision X-ray CT scans are used in engineering analyses to non-destructively view samples with volume elements as small as 10micro-meters, but this technique is problematic for non-rigid biological samples. Other problems arise from low x-ray contrast of tissue and the long scan times required. We will present results of micro-CT scans performed on biological samples as small as a bovine embryo and as large at a coyote skull. We will also discuss techniques to enhance the details captured in the x-ray images using contrast enhancers such as iodine (stains). We are working on post scan techniques to improve image quality, reduce scan times and to isolate items appearing in CT scans so they can be accurately recreated using a 3-D printer. Results and progress will be reported.</p