High molecular bands in RNA isolation sample

[monkey_SEQ]

I am attempting a de novo transcriptome assembly and have a question about genomic DNA contamination. I have treated my RNA samples twice with DNAseI (on-column and then afterwards in solution as it seemed that there was still HMW smears present). After both these treatments I still feel that I have not gotten rid of the HMW smears (see att 1% agarose gel, RNA ladder). I don’t have primers available to definitively test for gDNA. Could somebody please comment on what these HMW smear can be?

(PS. Only a single rRNA band present as this is an insect species with a ‘hidden break' in the 28S rRNA).

What effect will contaminated gDNA sequences have on the transcriptome assembly process?

Much appreciated

[ywg]

How about do a RNAase test. treat small aliquot of rRNA with RNAase. compare with and without RNAase to confirm it is real gDNA contamination?