Hi Pedro. The number of the RNA bands depend on the tissue you are using to extract. Which is the tissue type in your samples? On general the major bands belong to 28 and 18 sRNA some smaller could be tRNA , or 5.5s RNA even some very well expressed gene can reuslt as vidible RNA bands in the picture. I guess one of the cases I am writing is yours.

Hi Pedro, I agree with Yordan. It can be tissue specific and also species specific. It looks like fragmented 28S.

In my point of view it could not be other RNA bands like 5.5, tRNA or mRNA because these bands can appear below to the 18sRNA subunit, I think the band which appear below the 28s could be a degraded RNA sub unit, Elute these bands and do the RT hope that will show some thing

ctually I just gave an example when you have a lot of bands during RNA extraction they could be tRNA etc...For me the pointed band is more like well expressed gene.

Dear Yordan

 While extracting the RNA or DNA how can a gene can express to give a particular band? 

Dear Guruswamy,

in plants for example one of the most abundant mRNA is the RNA coding for 1,5-bisphosphate carboxylase oxygenase gene (RUBISCO) and when you extract total RNA, RUBISCO mRNA is very well visible on EtBr staining agarose gel. I was just giving some suggestions (a particular and very well expressed gene in his samples) to Pedro what might be the band he observed. I hope I understand well and  answered your question.

Regards,

Yordan

Hi Pedro,

In RNA extraction it is normal to have four bands which are genomic DNA, 28s, 18s rRNA and small RNA. The problem is your gel has 5 strong bands. Like others said I think the pointed band is not small RNA and I doubt it is mRNA from highly expressed gene. Here are some suggestions:

1. Try to rerun your gel with one or two samples from your "5bands samples". This just to make sure that this not a problem of gel running.

2. Try to digest your sample with DNase, this will give you idea whether your pointed band is DNA or RNA.

I think this band is most likely fragmented band. But it looks like it specific fragmentation (not from partial RNase or DNase digestion). Otherwise It could also be some DNA fragment contamination. Step 2 will give you some ideas about this.

Hope this will give you some hints what this band could be.

Thank you all for the answers. The samples are fibroblasts.

Dear Pedro

Today my agarose gel was exactly as same as your gel! I used glycogen in aquoa phase to increase the RNA yield. I think the band you pointed by flash is mRNA. 

could be 23s mt or cp rRNA