Prions are agents of analog, protein conformation-based inheritance that can confer beneficial phenotypes to cells, especially under stress. Combined with genetic variation, prion-mediated inheritance can be channeled into prion-independent genomic inheritance. Latest screening shows that prions are common, at least in fungi. Thus, there is non-negligible flow of information from proteins to the genome in modern cells, in a direct violation of the Central Dogma of molecular biology. The prion-mediated heredity that violates the Central Dogma appears to be a specific, most radical manifestation of the widespread assimilation of protein (epigenetic) variation into genetic variation. The epigenetic variation precedes and facilitates genetic adaptation through a general 'look-ahead effect' of phenotypic mutations. This direction of the information flow is likely to be one of the important routes of environment-genome interaction and could substantially contribute to the evolution of complex adaptive traits.

This happens through the production of proteins, which affect the organism’s characteristics. The process follows the central dogma of molecular biology, proposed by Francis Crick in 1958, which states that genetic information flows from DNA to RNA and then to protein. Gene expression involves two main steps: transcription, where DNA is copied into RNA, and translation, where RNA is used to build proteins. Gene expression A gene is a unit of heredity and is a section of DNA that carries the instructions for an organism’s form or function. DNA is made of two long chains of nucleotides that twist together to form a double helix. In eukaryotes, DNA is arranged in linear chromosomes, while in prokaryotes it is found in circular chromosomes. All of the chromosomes in a cell together make up its genome. In eukaryotic cells, most DNA is located in the nucleus, whereas in prokaryotic cells, it is found in a region called the nucleoid. The genetic information inside an organism is stored in its genes, and the complete set of this information is called the genotype.

In biology, changes to a DNA sequence can impact protein sequence but changes to protein sequences (phenotype) do not flow back into DNA (genotype). A system with bidirectional information flow (i.e., both translation and ‘reverse translation’) remains a theoretical possibility for an independent origin of life or an artificial biosystem, but the recent development of digital data storage in DNA does just this: changes made to a digital file can be written back into DNA, meaning changes to ‘phenotype’ can be written back to ‘genotype’. To explore the evolutionary properties of such a system, w