Beta-adrenergic agonists alter oxidative phosphorylation in primary myoblasts (Short Communication)

Beta-adrenergic agonists (β-AAs) are widely used supplements in beef and pork production to improve feed efficiency and increase lean muscle mass, yet little is known about the molecular mechanism by which β-AAs achieve this outcome. Our objective was to identify the influence of ractopamine HCl and zilpaterol HCl on mitochondrial respiratory activity in muscle satellite cells isolated from crossbred beef steers (N = 5), crossbred barrows (N = 2), Yorkshire-cross gilts (N = 3), and commercial weather lambs (N = 5). Real-time measurements of oxygen con­sumption rates (OCRs) were recorded using extracellular flux analyses with a Seahorse XFe24 analyzer. After basal OCR measurements were recorded, zilpaterol HCl, ractopamine HCl, or no β-AA was injected into the assay plate in three technical replicates for each cell isolate. Then, oligomycin, carbonyl cyanide-p-trifluoromethoxyphenylhydrazone, and rotenone were injected into the assay plate sequentially, each inducing a different cellular state. This allowed for the measurement of OCR at these states and for the calculation of the following measures of mitochon­drial function: basal respiration, non-mitochondrial respiration, maximal respiration, proton leak, adenosine triphosphate (ATP)-linked respiration, and spare respiratory capacity. Incubation of bovine cells with either zilpaterol HCl or ractopamine HCl increased maximal respiration (P = 0.046) and spare respiratory capacity (P = 0.035) compared with non-supplemented counterparts. No difference (P \u3e 0.05) was observed between zilpaterol HCl and ractopamine HCl for maximal respiration and spare respiratory capacity in bovine cell isolates. No measures of mitochondrial function (basal respiration, non-mitochondrial respiration, maximal respiration, proton leak, ATP-linked respiration, and spare respiratory capacity) were altered by β-AA treatment in ovine or porcine cells. These findings indicate that β-AAs in cattle may improve the efficiency of oxidative metabolism in muscle satellite cells by modifying mitochondrial respiratory activity. The lack of response by ovine and porcine cells to β-AA incubation also demonstrates differing physiological responses to β-AA across species, which helps to explain the variation in its effectiveness as a growth supplement. Lay Summary — Beta-adrenergic agonists (β-AAs) are supplemented to pigs and cattle to improve growth performance, carcass weight, and loin muscle area. Little is known about the mechanism taking place within individual cells by which β-AAs achieve this outcome. Previous work reported that β-AA supplementation improves the efficiency in which cells use glucose as an energy source and alters the expression of genes related to mitochondrial function, a key component of cellular energy production. To further our understanding of the impact of β-AA supplementation on these cellular functions, our objective was to identify the influence of two β-AAs used in livestock production, ractopamine HCl and zilpaterol HCl, on the mitochondrial respiratory activity of cells collected from the loin muscle and grown in culture. We isolated cells from cattle, pig, and sheep muscle and measured the oxygen consumption of the cells after treatment with ractopamine HCl, zilpaterol HCl, or with no supplement. We found that both ractopamine HCl and zilpaterol HCl enhance the efficiency of cellular energy production during a state of cellular stress in bovine muscle cells. There was no appreciable effect of the supplement on the energy production of pig or sheep cells. These data indicate that β-AA supplementation in cattle may increase the muscle cell energy production capacity compared with non-supplemented cells. This study also demonstrates that the efficiency of cell energy production is one plausible mechanism underlying species differences in the response to β-AA supplementation

The properties and applications of single-molecule DNA sequencing

Single-molecule sequencing enables DNA or RNA to be sequenced directly from biological samples, making it well-suited for diagnostic and clinical applications. Here we review the properties and applications of this rapidly evolving and promising technology

MEDPOL - Multimedia based pool for case related learning in medicine

In August 2003 the project MEDPOL was founded at the medical faculty of the Friedrich Schiller University Jena. MEDPOL stands for "multimedia based pool for case related learning in medicine". Hospitals and institutes of the faculty are offered to prepare typical casestudies for interdisciplinary eLearning. The students are given the possibility to practice at virtual patients close-to-reality. The simulation includes anamnesis, clinical investigations, technical and laboratory studies as well as the necessary treatment. Assistance is given if necessary, especially to find right diagnosis. Finally all steps are evaluated in form of statistics. Because of integration in a Learnmanagementsystem (LMS) the presentation of the content is highly flexible and the effort of course administration, point assignment, forum etc. is turned to minimum. MEDPOL is same as suitable as for continuing medical education (CME).For further information to the project please notice: http://www.medpol.uni-jena.deIm August 2003 wurde an der medizinischen Fakultät der Friedrich-Schiller-Universität Jena das Projekt MEDPOL ins Leben gerufen. MEDPOL steht für "Multimedialer Fallpool für problemorientiertes Lernen in der Medizin". Den Kliniken und Instituten der Fakultät wird angeboten, exemplarische Fälle ihres Fachgebietes interdisziplinär für das problemorientierte Lernen aufzubereiten. Den Studierenden soll damit die Möglichkeit gegeben werden, an virtuellen Patienten realitätsnah zu üben. Die Simulation umfasst die Anamneseerhebung, körperliche Untersuchungen, Geräte- und Laboruntersuchung sowie die Anordnung der erforderlichen therapeutischen Maßnahmen. Bei Bedarf können systematische Informationsquellen in Anspruch genommen werden, insbesondere um die richtige Diagnose zu stellen und nach aktuellen Richtlinien zu verschlüsseln. Die einzelnen Schritte werden abschließend in Form einer Statistik ausgewertet und die Ergebnisse beurteilt.Durch die Einbindung in ein Learnmanagementsystem (LMS) werden die Lerninhalte flexibel präsentiert, und der administrative Aufwand für Kursverwaltung, Punktevergabe, Forum etc. minimiert.MEDPOL ist neben der Medizinerausbildung auch für die ärztliche Fortbildung geeignet.Weitere Informationen zum Projekt finden Sie unter: http://www.medpol.uni-jena.d

Visualization_1_Spectral_Vortex.avi

Rotation of the spectral anomaly ("spectral eyes") of a propagating femtosecond polychromatic Bessel-Gauss beam around the phase singularity. Spectral maps were obtained by scanning the planes with a fiber delivering the signal to the grating spectrometer. The movie shows a complete rotation of the first spectral moment (centers of gravity) by 360° in axial steps of 10 µm (FOV: 162 µm x 181 µm, in close proximity to the singularity). The rotation continues over several cycles of rotation at a nearly constant rate and slows down in the region of spectral phase compensation