Scientists have proposed what they believe is the first method for detecting ‘mirror life’ – a hypothetical form of life made from molecular building blocks that are the mirror image of those found naturally on Earth.
Researchers at the University of Strathclyde and Durham University have outlined a new approach which could potentially identify mirror organisms using molecules which emit left and right-handed light, providing a possible future surveillance tool should the ability to create such organisms ever emerge.
Mirror life is considered a low-likelihood but potentially high-severity biosecurity threat. There are international concerns that artificially created mirror organisms could interact with the natural world in unpredictable ways and potentially evade some of the biological defences which protect humans, animals and plants.
Mirror organisms
Scientists have called for restrictions on research aimed at creating the self-replicating mirror organisms, while the potential risks have also been considered by governments and international organisations, including the UK Government Office for Science and the United Nations Secretary General’s Scientific Advisory board.
Even though left- and right-handed molecules have exactly the same atoms in the same order, they interact differently with living bodies. While one version of a medicine might cure an illness, the mirror-image version may do nothing or cause harm.
The researchers, who stress that mirror life does not currently exist and their proposed method is intended as a contingency measure, use an approach involving circularly polarised luminescence (CPL). A property of light, it can reveal information about the ‘handedness’, or chirality, of molecules and biological structures.
Everyday uses
Circularly polarised light is already familiar from an everyday application – the technology used to create the stereoscopic effect in 3D cinema glasses.
The paper, ‘Circularly Polarised Luminescence (CPL) as a Contingency Assay for “Mirror Life” Bio-Hazards’, published in Royal Society Open Science, was led by Dr Lewis MacKenzie, of Strathclyde’s Department of Pure and Applied Chemistry, in collaboration with Professor Robert Pal, of Durham University.
Dr MacKenzie said: “We don’t expect mirror life to appear tomorrow, but if it did arise, the consequences could be severe, and it makes sense to develop detection methods before they are needed. Professor Pal and I had been working on CPL technologies before recent concerns became prominent, and guarding against mirror life was a clear fit for our research.”
The researchers propose using fluorescent probes which bind to structures within cells and produce distinctive CPL signals. These signals could provide a molecular fingerprint indicating whether a biological sample has the conventional chirality found in terrestrial life or its mirror image.
To minimise the possibility of false results, the paper proposes using a panel of different probes targeting several biological structures rather than relying on a single measurement.
Biological samples
The proposed approach could be tested and developed using conventional biological samples without creating mirror organisms.
The team suggest that the mirror life detection technique could eventually be used with a wide range of devices. Existing CPL detection technologies such as microscopes, cameras, and biological cell plate readers have already been demonstrated at laboratory scale by Professor Pal, although a complete mirror-life detection assay has not yet been experimentally demonstrated.
Professor Pal added: “CPL detection relies on the same fundamental concept that allows modern 3D cinema glasses to create a stereoscopic image.
"This CPL detection approach can be adapted to many types of systems for analysis of cells, including biological plate readers, microscopes, and cameras. This means our mirror life assay approach could be generalised to many environments depending on end user needs.”