Group of scientists urge halt research on Mirror Life Microbes

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 Mirror life (also called mirror-image life) is a hypothetical form of life with mirror-reflected molecular building blocks. The possibility of mirror life was first discussed by Louis Pasteur. Although this alternative life form has not been discovered in nature, efforts to build a mirror-image version of biology's molecular machinery are already underway. Some scientists have proposed banning the creation of mirror life, including mirror bacteria, due to its potential to escape immune defenses and invade natural ecosystems.

Homochirality

Many of the essential molecules for life on Earth can exist in two mirror-image forms, referred to as "left-handed" and "right-handed" where handed refers to direction in which polarized light skews when beamed through a pure solution of the molecule, but living organisms do not use both. Proteins are exclusively composed of left-handed amino acids; RNA and DNA contain only right-handed sugars. This phenomenon is known as homochirality. It is not known whether homochirality emerged before or after life, whether the building blocks of life must have this particular chirality, or indeed whether life needs to be homochiral. Protein chains built from amino acids of mixed chirality tend not to fold or function as catalysts, but mirror-image proteins have been constructed that work the same but on substrates of opposite handedness.

The concept

Hypothetically, it should be possible to recreate an entire ecosystem from the bottom up, in mirror form.

Advances in synthetic biology, like synthesizing viruses since 2002, partially synthetic bacteria in 2010, or synthetic ribosomes in 2013, may lead to the possibility of fully synthesizing a living cell from small molecules, where we could use mirror-image versions (enantiomers) of life's building-block molecules, in place of the standard ones. Some proteins have been synthesized in mirror-image versions, including polymerase in 2016.

Reconstructing regular lifeforms in mirror-image form, using the mirror-image (chiral) reflection of their cellular components, could be achieved by substituting left-handed amino acids with right-handed ones, in order to create mirror reflections of all regular proteins. Analogously, one could create reflected sugars, DNA, etc., on which reflected enzymes would work perfectly. Finally, there could be a normally functioning mirror reflection of a natural organism—a chiral counterpart organism.

Electromagnetic force (chemistry) is unchanged under such molecular reflection transformation (P-symmetry). There is a small alteration of weak interactions under reflection, which can produce very small corrections, but these corrections are many orders of magnitude lower than thermal noise—almost certainly too tiny to alter any biochemistry. However, there are also theories that weak interactions can have a greater effect on longer nucleic acids or protein chains, resulting in much less efficient conversion of mirror ribozymes or enzymes than normal ribozymes or enzymes.

Mirror animals would need to feed on reflected food, produced by reflected plants. Mirror viruses would not be able to attack natural cells, just as natural viruses would not be able to attack mirror cells.

Mirror life presents potential dangers. For example, a chiral-mirror version of cyanobacteria, which only needs achiral nutrients and light for photosynthesis, could take over Earth's ecosystem due to lack of natural enemies, disturbing the bottom of the food chain by producing mirror versions of the required sugars. Some bacteria can digest L-Glucose; exceptions like this would give some rare lifeforms an unanticipated advantage.

  1. Wikipedia
  2. The Guardian
  3. Firstpost
  4. Times of India
  5. Bulletin of the Atomic Scientists


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