Publications by authors named "Joseph M Dragavon"

4 Publications

  • Page 1 of 1

Estrogen receptor profiling and activity in cardiac myocytes.

Mol Cell Endocrinol 2016 08 7;431:62-70. Epub 2016 May 7.

University of Colorado at Boulder, Department of Molecular, Cellular, and Developmental Biology, BioFrontiers Institute, Boulder, CO 80303 USA.

Estrogen signaling appears critical in the heart. However a mechanistic understanding of the role of estrogen in the cardiac myocyte is lacking. Moreover, there are multiple cell types in the heart and multiple estrogen receptor (ER) isoforms. Therefore, we studied expression, localization, transcriptional and signaling activity of ERs in isolated cardiac myocytes. We found only ERα RNA (but no ERβ RNA) in cardiac myocytes using two independent methods. The vast majority of full-length ERα protein (ERα66) localizes to cardiac myocyte nuclei where it is competent to activate transcription. Alternate isoforms of ERα encoded by the same genomic locus (ERα46 and ERα36) have differential transcriptional activity in cardiac myocytes but also primarily localize to nuclei. In contrast to other reports, no ERα isoform is competent to activate MAPK or PI3K signaling in cardiac myocytes. Together these data support a role for ERα at the level of transcription in cardiac myocytes.
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http://dx.doi.org/10.1016/j.mce.2016.05.004DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4899180PMC
August 2016

In vitro characterization of Fluorescence by Unbound Excitation from Luminescence: broadening the scope of energy transfer.

Methods 2014 Mar 14;66(2):353-61. Epub 2013 Sep 14.

Plate-Forme d'Imagerie Dynamique, Imagopole, Institut Pasteur, 25-28 Rue du Dr. Roux, 75724 Paris cedex 15, France. Electronic address:

Energy transfer mechanisms represent the basis for an array of valuable tools to infer interactions in vitro and in vivo, enhance detection or resolve interspecies distances such as with resonance. Based upon our own previously published studies and new results shown here we present a novel framework describing for the first time a model giving a view of the biophysical relationship between Fluorescence by Unbound Excitation from Luminescence (FUEL), a conventional radiative excitation-emission process, and bioluminescence resonance energy transfer. We show here that in homogeneous solutions and in fluorophore-targeted bacteria, FUEL is the dominant mechanism responsible for the production of red-shifted photons. The minor resonance contribution was ascertained by comparing the intensity of the experimental signal to its theoretical resonance counterpart. Distinctive features of the in vitro FUEL signal include a macroscopic depth dependency, a lack of enhancement upon targeting at a constant fluorophore concentration cf and a non-square dependency on cf. Significantly, FUEL is an important, so far overlooked, component of all resonance phenomena which should guide the design of appropriate controls when elucidating interactions. Last, our results highlight the potential for FUEL as a means to enhance in vivo and in vitro detection through complex media while alleviating the need for targeting.
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http://dx.doi.org/10.1016/j.ymeth.2013.09.005DOI Listing
March 2014

Intrinsic autotrophic biomass yield and productivity in algae: experimental methods for strain selection.

Biotechnol J 2011 May 7;6(5):572-83. Epub 2011 Mar 7.

Faculty of Life-Sciences, University of Manchester, Manchester, UK.

Using an analogy with fed-batch heterotrophic growth, the algal photoautotrophic yield Φ(DW) (in grams of dry weight biomass synthesized per micromole of absorbed photons) was derived from the algae batch growth behavior in nutrient-replete medium. At known levels of incident light, the yield Φ(DW) enables the estimate of a maximum productivity, and is therefore critical to compare and select algal cultures and growth conditions for large-scale production. The algal culture maximum growth rate was shown to be an unreliable indicator of autotrophic biomass yield. The developed carbonate addition method (carbonate addition, neutralization, and sealing) alleviated carbon limitations otherwise seen in aerated batch cultures, leading to two to five fold higher yield estimates. The fully defined FLX growth medium with variable ionic strengths (FLX1-100) supported excellent growth in most cultures tested. The chosen experimental methods and versatile FLX medium proved well-suited for small sample volumes and a high number of samples.
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http://dx.doi.org/10.1002/biot.201000260DOI Listing
May 2011

A New Approach for Measuring Single-Cell Oxygen Consumption Rates.

IEEE Trans Autom Sci Eng 2008 Jan;5(1):32-42

Department of Electrical Engineering, University of Washington, Seattle, WA 98195-2500 USA ( ; ).

A novel system that has enabled the measurement of single-cell oxygen consumption rates is presented. The experimental apparatus includes a temperature controlled environmental chamber, an array of microwells etched in glass, and a lid actuator used to seal cells in the microwells. Each microwell contains an oxygen sensitive platinum phosphor sensor used to monitor the cellular metabolic rates. Custom automation software controls the digital image data collection for oxygen sensor measurements, which are analyzed using an image-processing program to yield the oxygen concentration within each microwell versus time. Two proof-of-concept experiments produced oxygen consumption rate measurements for A549 human epithelial lung cancer cells of 5.39 and 5.27 fmol/min/cell, closely matching published oxygen consumption rates for bulk A549 populations.
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http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2971563PMC
http://dx.doi.org/10.1109/tase.2007.909441DOI Listing
January 2008
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