But between DNA and proteins comes RNA, and an expanding realm of complexity. RNA is a shape-shifter, sometimes carrying genetic messages and sometimes regulating them, adopting a multitude of structures that can affect its function. In a paper published in this issue (see page 53), a team of researchers led by Benjamin Blencowe and Brendan Frey of the University of Toronto in Ontario, Canada, reports the first attempt to define a second genetic code: one that predicts how segments of messenger RNA transcribed from a given gene can be mixed and matched to yield multiple products in different tissues, a process called alternative splicing. This time there is no simple table — in its place are algorithms that combine more than 200 different features of DNA with predictions of RNA structure.
The work highlights the rapid progress that computational methods have made in modelling the RNA landscape. In addition to understanding alternative splicing, informatics is helping researchers to predict RNA structures, and to identify the targets of small regulatory snippets of RNA that do not encode protein. "It's an exciting time," says Christopher Burge, a computational biologist at the Massachusetts Institute of Technology in Cambridge. "There's going to be a lot of progress in the next few years."
The floodgates were opened by high-throughput technologies that allow researchers to compile comprehensive catalogues of RNA molecules found in various tissues and under different environmental conditions. Such techniques revealed that 95% of the human genome is alternatively spliced, and that changes in this process accompany many diseases. But no one knew how to predict which form of a particular gene would be expressed in a given tissue. "The splicing code is a problem that we've been bashing our heads against for years," says Burge. "Now we finally have the technologies we need."
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There ar many Signs on earth for those of sure faith, and also in your own selves. Do you not see? Quran (51 : 20, 21)