How to interpret bimodal distribution of GC-content for RNAseq and can it be remedied ?

Question

[Alexander]

A colleague of mine have got the following distribution of GC-content for RNAseq.

How to interpret bimodal distribution of GC-content for RNAseq ? Does it mean some contamination ? Is there any method to remedy ?

[patelk26]

A broad peak usually indicates contamination. To confirm that, you can run fastQ screen.

FastQ screen allows you to search a large sequence dataset against a panel of different genomes to determine from where the sequences in your data originate.

[GenoMax]

Start checking for contamination with rRNA.