For the reader's convenience, a user-friendly and publicly accessible web-server named sgRNA-PSM has been established. Here, a step-by-step guide on how to use the webserver to get a desired result without the need to carefully understand the mathematical details.The high activity means the predicted score is larger than 0.85, the low activity means the predicted score is smaller than 0.85.

  Note that: (i) the web server allows user to input sgRNA sequence not only in order ((N)4-(N)20-NGG-(N)3), but also in reverse-complementary order ((N)3-CCN-(N)20-(N)4). (ii) the web server allows user to input a longer sequence not only the sgRNAs (i.e, 30~1000bp), and can give all of the possible sgRNAs with predicted scores.

  Step 1. Open the web-server at http://bliulab.net/sgRNA-PSM/ and you will see its top page of sgRNA-PSM. Click on the ReadMe button to see a brief introduction about the server.

  Step 2. Type or copy/paste the query sequences into the input box, or you can also directly upload your input data via the Browse button. The input sequence should be in the FASTA format. For the examples of sequences in the FASTA format, click the Example button right above the input box.

  Step 3. Click on the Submit button to see the predicted results. For example,and use the four query DNA sequences in the Example window as the input, you will see on your computer screen: you will see that the 1st and 2nd are predicted as high on-target activity sgRNAs, while the 3rd is the sequence in reverse-complementary order, it is predicted as low on-target activity sgRNA, the 4th has 4 low on-target activity sgRNAs and 1 high on-target activity sgRNAs. All these results are fully consistent with the experimental observations.In order to help the users to solve the problems when using the web server, the FQA was provided by clicking on the FQAbutton.