Update README.md

README.md

@@ -6,6 +6,8 @@ UROBORUS is a software tool for circular RNA identification from RNA-Seq data se
 
 Recent evidence suggested that many endogenous circular RNAs (circRNAs) may play roles in biological processes. However, the presence of circRNAs and their expression patterns in human species are not well understood. Computationally identifying circRNAs from RNA-seq data is a primary step to study their expression pattern and biological roles. Here, we have developed computational pipeline named UROBORUS to detect circRNAs in total RNA-seq data. Compared with two available computational approaches, UROBORUS is an easy-to-use and efficient tool that can detect circRNAs with low expression levels in total RNA-seq without RNase R treatment. 
 
+Please note that circular RNA does not has PloyA tail, so you can not detect any circRNA in PolyA RNA-seq. You should use PolyA minus or total RNA-seq data to detect circular RNA.
+
 ## Documentation
 
 Documentation on the software can be found at http://uroborus.openbioinformatics.org.