Chimps \'r not us (Introduction)

by David Turell , Tuesday, March 03, 2015, 18:11 (3554 days ago) @ David Turell

Chimps have about 98% the same genes as us taken just on a total score. But they are not arranged the same way and all the modifiers of gene expression result in an overall difference that is estimated by various authors to be around 80%. Now a new study looking at newly found miRNAs, the very short modifiers (24 bases), finds that 56.7% are unique to humans. Lots of evolutionary change in the genome produced humans it seems:-"In the early days of the miRNA field, there was an emphasis
on identifying miRNAs that are conserved across organisms: e.g.,
let-7 first described in 2000 (63, 64). Nonetheless, species-specific
miRNAs (e.g., cel-lsy-6 in C. elegans) (62) have also been described
and characterized as have been miRNAs that are present
only in one or a few species of the same genus. Therefore, enforcing
an organism-conservation requirement during miRNA
searches is bound to limit the number of potential miRNAs that
can be discovered, leaving organism- and lineage-specific miRNAs
undiscovered (53-56). In our effort to further characterize the
human miRNA repertoire, we liberated ourselves from the conservation
requirement: not surprisingly then, 56.7% of our newly
discovered miRNAs are human-specific whereas 94.4% are primate-
specific (Table 2). Considering that many miRNA studies to
date have focused on seeking and analyzing conserved miRNAs,
it is not surprising that, of the human miRNAs in miRBase, we
found a larger fraction to be conserved in rodents and invertebrates
(Table 2). These findings strongly suggest the possibility of
a wide-ranging species-specific miRNA-ome that has yet to be
characterized. Indeed, it is reasonable to expect that at least some
of these novel primate-specific miRNAs participate in unexplored
aspects of regulatory processes that cannot be captured by the
currently available mouse disease models. Thus, not only could
these newly discovered miRNAs provide new molecular insights
but they could also help us define novel biomarkers for tissue or
disease states."-http://www.pnas.org/content/early/2015/02/18/1420955112.long