Vastly increased interest in the subtle aspects of RNA chemistry and biology in the last two decades is justified by unique properties of RNA molecules, which are fascinating from both fundamental and applied point of view.

RNA is able to bind different biological targets and to catalyze diverse chemical reactions. By molecular elucidation of its 3D structures and relating their intricate framework to the specific properties of native RNA, we can obtain vital clues to how specific functions are performed.

It is thought that life on Earth went through a stage when RNA molecules were the primary functional biopolymers: the RNA world. In every living organism and some viruses, RNA is intimately involved into molecular aspects of life. It works as a genetic information storage device in RNA-containing viruses such as HIV-1 and HCV. Riboswitches are noncoding RNAs that regulate gene expression in response to changes in cellular environment. MicroRNAs (miRNAs) are small noncoding transcripts involved in the posttranscriptional modulation of gene expression. In various organisms, RNA interference (RNAi) is an activity that leads to translational arrest or the degradation of the complementary mRNA. rRNA catalyses a key step of peptide bond formation in the ribosome.

The multitude of roles played by RNA opens broad avenues for biological and medicinal applications where RNA is a target for various classes of RNA-binding agents for example, siRNA, antisense oligonucleotides, nucleic acid enzymes, aptamers as well as small RNA-binding molecules and artificial ribonucleases. For instance, Macugen has been approved by the FDA as the first aptamer drug against VEGF in December 2004.

This Special Issue of the Journal of Nucleic Acids will focus on the use of chemistry in its broadest sense to gain insights into fundamentals of RNA biology. We would like to invite authors to present accounts of original research as well as overviews of hot topics on the chemical approaches helping us to understand better various aspects of RNA science. Potential topics may include, but are not limited to the following:

• Insights into RNA structure
• The RNA world and primordial evolution of RNA
• RNAi and siRNA
• MicroRNA
• Ribozymes
• Riboswitches
• RNA aptamers
• Ribosome
• Artificial ribonucleases
• Chemical synthesis of RNA

Before submission authors should carefully read over the journal's Author Guidelines, which are located at http://www.hindawi.com/journals/jna/guidelines/. Prospective authors should submit an electronic copy of their complete manuscript through the journal Manuscript Tracking System at http://mts.hindawi.com/ according to the following timetable: