ARTIFICIAL GRAVITY FOR MICROORGANISMS
The single-cell organism Paramecium caudatum employs a process known as gravikinesis, the act of regulating its swimming speed depending on whether it swims with or against the force of gravity. Gravikinesis fights the paramecium's natural tendency to settle to the bottom of a body of water and form sediment; as a result it swims harder upward than downward. Karine Guevorkian (guevorkian@physics.brown.edu) and James M Valles Jr. of Brown University have successfully observed and quantified gravikinesis in Paramecium using a magnetic-force gravity simulation technique. The simulation approach employs magnetic forces that can be directed to pull in tandem with gravity's forces to create enhanced gravity or to push in opposition to gravity to create weakened and even inverted gravity (in which the organism moves opposite to the direction of gravitational force).. These strong magnetic forces are generated by intense inhomogeneous magnetic fields such as those available at the National High Magnetic Field Laboratory acting on the "diamagnetic" materials naturally present in cells. Besides reproducing results obtained from high gravity in a centrifuge chamber, the technique allowed the researchers to investigate the swimming speed regulation in decreased and inverted simulated gravity.(Paper B29.3)

NANOPORE DNA SEQUENCING
Some proteins naturally form nanometer-scale pores through which ions travel to enable communication within and between nerve cells. Researchers are developing biotechnology applications for natural and artificial versions of such nanopores. For example, nanopores are coming closer to enabling faster and better DNA sequencing than present biochemistry-based methods. In the general concept, DNA would traverse through the pore, and in one scenario the change in ion cu
'"/>

Contact: James Riordon
riordon@aps.org
301-209-3238
American Physical Society
17-Mar-2006