非表示:
キーワード:
gene emergence; phylostratigraphy; noncoding RNA; lineage‐specific adaptations; overprinting
要旨:
Orphangenes are genes that occur in specific evolutionary
lineages without similarity to genes outside of these lineages
and have, therefore, alternatively been named
taxonomically restricted genes. They were so far considered
to emerge through duplication–divergence processes,
but it isnowbecomingclear that they can also arise
de novo out of noncoding deoxyribonucleic acid (DNA).
This latter process may even occur much more frequently
than previously assumed. It appears that genomes harbour
many transcripts in a transition stage from nonfunctional
to functional genes, also knownas protogenes,
which are exposed to evolutionary testing and can
become fixed when they turn out to be useful. Orphan
genes may have played key roles in generating lineagespecific
adaptations and could be a continuous source of
evolutionary novelties. Their existence suggests that
functional ribonucleic acids (RNAs) and proteins can
relatively easily arise out of randomnucleotide sequences,
although these processes still need to be experimentally
explored.
