Lab. Life Sci. for Extremophiles

Although it is still difficult to reconstruct and revive past organisms with current scientific technology, it is becoming possible to reconstruct and revive genes or proteins. In our laboratory, we have already created molecular phylogenetic trees of several proteins based on their extant homologous amino acid sequences and inferred the amino acid sequences of proteins that were likely present in the common ancestors of organisms by tracing back these trees. Many of the proteins with inferred ancestral amino acid sequences were found to exhibit high thermal stability. This result strongly suggests that the ancestral organisms that possessed these ancestral proteins were thermophiles or hyperthermophiles thriving in high-temperature environments.
　In the future, we will challenge to reconstruct many types of ancestral proteins. In addition, it is expected that the past Earth environment in which ancestral organisms lived, such as the ocean pH, carbon dioxide and oxygen levels will be clarified. Ultimately, we would like to attempt the dream-like challenge of reconstructing the entire genome of the last universal common ancestor and resurrecting the organism itself.