  Although conservation of thermodynamics is much less studied than of
sequences and structures, thermodynamic details are biophysical features
different from but as important as structural features. As a succession of
previous research which revealed the important relationships between
thermodynamic features and miRNA maturization, this article applies
interspecies conservation of miRNA thermodynamics and structures to study miRNA
maturization. According to a thermodynamic and structural consensus principle,
miRBase is categorized by conservation subgroups, which imply various
functions. These subgroups are divided without the introduction of functional
information. This suggests the consistency between the two processes of miRNA
maturization and functioning. Different from prevailing methods which predict
extended miRNA precursors, a learning-based algorithm is proposed to predict
~22bp mature parts of 2780 test miRNA genes in 44 species with a rate of 79.4%.
This is the first attempt of a general interspecies prediction of mature
miRNAs. Suboptimal structures that most fit the consensus thermodynamic and
structural profiles are chosen to improve structure prediction. Distribution of
miRNA locations on corresponding pri-miRNA stem-loop structures is then
studied. Existing research on Drosha cleavage site is not generally true across
species. Instead, the distance between mature miRNA and center loop normalized
by stem length is a more conserved structural feature in animals, and the
normalized distance between mature miRNA and ss-RNA tail is the counterpart in
plants. This suggests two possibly-updating mechanisms of miRNA maturization in
animals and plants. All in all, conservations of thermodynamics together with
other features are shown closely related to miRNA maturization.
