The Role of Extracellular ATP in Dictyostelium discoideum Growth and Development

It has long been known that the social amoeba Dictyostelium discoideum initiates and controls its developmental processes by the creation and transmission of the purinergic molecule; cyclic AMP. It is also known that it possesses P2X receptors which are localised on the inside of the cell. Despite the lack of cell surface ATP receptors, previous studies have indicated the existence of Dictyostelium ecto-ATPases and calcium responses to the addition of exogenous ATP. In these experiments it was found, using the luciferase assay, that the cells condition their media with ATP during axenic growth and development. Treatment of cells with apyrase, a potato enzyme known to degrade ATP, did not affect the rate of growth, but led to a delay in the appearance of streams during development. This delay corresponded with the formation of “clumps” of cells, but no evidence could be found that the cells had increased expression of adhesion molecules. Apyrase also caused developing cells to form fewer fruiting bodies, despite the fact that there was no difference in the number of aggregates formed, implying that the apyrase was interfering in the transition between these stages. The apyrase fruiting bodies also contained fewer viable cells, though whether it was fewer cells in general or less healthy ones could not be confirmed. The malachite green assay was used to measure the rate of activity of the cell surface ecto-ATPases and the results suggested that the common ecto-ATPase inhibitor suramin would affect them. Cells allowed to develop in the presence of suramin showed no abnormal timing in the stages of development or in number of fruiting bodies, but did contain significantly more viable cells. Altogether these results are consistent with the hypothesis that ATP, ATP receptors and ATPases play a role in the regulation and co-ordination of development in Dictyostelium discoideum, despite the fact that it possesses no known cell surface P2X receptors

How to annoy reporters

A review of the BC Library Conference session "How to annoy reporters and hurt your credibility," presented by Stephen Barrington of Vancouver Public Library. Stephen offers helpful tips on how to work with reporters, get your library in the news and put your message out there.&nbsp

USING A REVERSE VISUALLY GUIDED REACHING TASK TO DISTINGUISH BETWEEN HEALTHY AGING AND EARLY ALZHEIMER’S DISEASE

Changes in motor behavior may function as a proxy for cognitive decline. While Alzheimer\u27s disease (AD) is associated with impairments in learning and memory, recent studies suggest that subtle changes in motor task performance may reflect early cognitive changes. For example, the visuomotor rotation task that manipulates visual feedback about hand position during reaching movements, can be used to examine cognitive changes in aging populations. The current study used the reverse visually guided reaching task (rVGR) which rotates visual feedback of participant’s hand position 180⁰ relative to the actual hand position. We sought to expand on previous literature by recruiting cognitively impaired individuals to characterize changes in rVGR performance in early AD. We also examined learning curves to assess the impact of cognitive impairment on learning in the rVGR task and probed the cognitive correlates of rVGR performance with a neuropsychological battery. We recruited young adults, and older adults (55 – 85 years old) with and without cognitive impairment to complete a VGR task with veridical mapping, and then the rVGR task. Overall, cognitively impaired adults exhibited longer reaction times and performed more corrective movements. Age differences were observed for nearly all overall measures of performance. The largest differences between healthy older adults and cognitively impaired adults were identified in the earliest stages of the learning curve. In the first few movements, the cognitively impaired group made more angular errors. Both overall- and early- measures of performance were correlated with measures of cognitive control. These findings add to the growing literature suggesting that sensorimotor adaptation tasks may be sensitive to early cognitive changes in AD

Analysis of HHS Final Rules on Reinsurance, Risk Corridors and Risk Adjustment

Summarizes final rules for states and health insurance plans for minimizing adverse selection under federal healthcare reform and highlights changes from proposed rules. Outlines implications for states and plans, as well as outstanding issues

Analysis of HHS Proposed Rules on Reinsurance, Risk Corridors and Risk Adjustment

Offers questions and answers about rules for lessening the financial risk of health insurance issuers and exchanges under healthcare reform. Outlines steps for states and health plans, outstanding issues, and operational impact on states

Base Metals Prospecting in Kagera Region, Tanzania Using Remote Sensing and Biogeochemistry Analytics

This paper explores the use of biogeochemistry as a means for conducting geological prospecting in search of economic grade anomalies of precious metals, base metals and rare earth elements. The use of randomized soil sampling for geostatistical coefficient calculations and aeromagnetic remote sensing systems in conjunction with biogeochemical prospecting for ferromagnetic elements is examined. The paper concludes that the evidence presented indicates that bioprospecting can be an extremely powerful economic geology tool for conducting rapid and cost effective micro-targeting mineral discovery