Bacteria have been genetically engineered to produce distinctive ultrasound signals, making then potentially useful for medical imaging. Protein-enclosed pockets known as “gas vesicles” are usually found in aquatic bacteria to keep them buoyant, but a team of biophysicists led by Mikhail Shapiro at the California Institute of Technology has created a gene that allows the vesicles to appear in other bacteria.
Shapiro’s team showed how pulses of ultrasound waves passing through their modified bacteria were scattered in characteristic patterns, which were picked up as echoes by the ultrasound detector. This scattering is caused by the density difference between gas vesicles and their surroundings. However, above a certain pulse pressure, the vesicles collapsed, meaning ultrasound waves passed through the bacteria undisturbed. This collapse changed the detected signal abruptly.
Vesicles - Shapiro - Team - Signal - Noise
Once the vesicles collapsed, Shapiro’s team realized that the remaining detected signal could be considered background noise, which they could subtract from the scattered signal to produce high-resolution images of where the...
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