There is another remarkable feature of miRNAs in Dicty:

The RbdB KO has essentially no detectable levels of miRNAs. As far as we 
can see there is no obvious mutant phenotype in growth and development 
in this strain. One may certainly do a more detailed analysis but in 
contrast to expectations (at least mine) the cells appear quite happy. I 
can envision three explanations: 1. miRNAs are just there for fun (quite 
unlikely), 2. miRNAs are essential for sub-optimal conditions in the 
wild, 3. miRNAs are essential for the sexual cycle (which is difficult 
to investigate and is ignored by most people in the field).