added ref to Pressman:2017

TeX/biblio.bib

@@ -1455,3 +1455,15 @@ CONCLUSION: Adaptation time of molecular quasispecies to a given environment is
   year={2013},
   publisher={Springer}
 }
+
+@article{Pressman:2017,
+author = {Pressman, Abe and Moretti, Janina E. and Campbell, Gregory W. and Müller, Ulrich F. and Chen, Irene A.},
+title = {Analysis of in vitro evolution reveals the underlying distribution of catalytic activity among random sequences},
+journal = {Nucleic Acids Research},
+volume = {45},
+number = {14},
+pages = {8167-8179},
+year = {2017},
+doi = {10.1093/nar/gkx540},
+eprint = {/oup/backfile/content_public/journal/nar/45/14/10.1093_nar_gkx540/3/gkx540.pdf},
+}

TeX/introduction.tex

@@ -4,7 +4,7 @@
 
 %\subsection{RNA and the origin of life}
 % RNA world
-RNA are versatile molecules that can fulfil virtually all fundamental needs and functions of the living, from storing information to catalyzing chemical reactions and regulating gene expression. The RNA world hypothesis \citep{Gilbert:1986aa,Eddy:2001aa} builds upon this observation to describe a scenario of the emergence of life based on RNAs. Recent experimental  studies showing the remarkable adaptability of nucleic acids contributed to strengthen this hypothesis \citep{Horning:2016aa,Becker:2016aa} and thus revived the interest of the scientific community for this theory.
+RNA are versatile molecules that can fulfil virtually all fundamental needs and functions of the living, from storing information to catalyzing chemical reactions and regulating gene expression. The RNA world hypothesis \citep{Gilbert:1986aa,Eddy:2001aa} builds upon this observation to describe a scenario of the emergence of life based on RNAs. Recent experimental  studies showing the remarkable adaptability of nucleic acids contributed to strengthen this hypothesis \citep{Horning:2016aa,Becker:2016aa,Pressman:2017} and thus revived the interest of the scientific community for this theory.
 
 % key assumption
 Non-coding RNAs acquire functions through complex structures. A theory describing how nucleic acids evolve to ``discover'' these functional structures is thus a milestone toward a validation of the RNA world hypothesis \citep{Higgs:2015aa}. 

TeX/main_maternal.tex

@@ -21,6 +21,7 @@
 \usepackage{chngcntr}
 \graphicspath{{../Figures_Submit/}}
 
+
 % Bibliography 
 \usepackage[super,comma,sort&compress]{natbib}
 

TeX/methods.tex

@@ -77,6 +77,7 @@ In contrast \RNAmutants~\citep{Waldispuhl:2008aa} can sample pairs of sequence-s
 and (2) the probability of seeing the pair is  proportional to its \emph{fitness} compared to all  pairs
 $(\omega', s')$ where $w'$ is also an $k$-mutant of $\omega_0$.
 
+
 In addition \RNAmutants provides an unbiased control of the samples GC content allowing direct comparisons with
 \maternal.