Biological Imaging in Animals with Genetically Encoded Magnetic Reporters
30 January 2013
Dr. David Schaffer, Dr. Mikhail Shapiro, Dr. Arash Komeili, Dr. Steven Conolly
Genetically encoded optical reporters such as the green fluorescent protein (GFP) have revolutionized biology by making it possible to directly observe cellular processes such as gene expression. However, because light does not penetrate whole animals, fluorescent reporters have limited utility for the study of many of today's key biomedical questions, such as how tumors spread, how immune cells find pathogens, or how brain cells degenerate. Magnetic resonance imaging (MRI) can image whole organisms non-invasively, but at present there are no sensitive genetically encoded MRI reporters analogous to GFP. The team proposes to develop a "magnetic GFP" by borrowing genes from magnetotactic bacteria—organisms that use the Earth's magnetic field to navigate their environment. Magnetotactic bacteria contain iron nanoparticles known as magnetosomes that can be sensitively detected with MRI. Their unique multidisciplinary team will isolate a set of genes from these bacteria that are responsible for magnetosome formation, then transfer them into mammalian cells and animals to enable MRI of specific cellular processes. The resulting technology could transform biomedicine by opening a broad range of biological questions being studied in whole animals, thereby enabling fundamentally new studies in cancer, immunology, neuroscience and many other areas.