Due to residual gDNA contamination, will EtOH precipitate in order to treat with DNase again. Add 0.5 vols 3M NaAOc (pH=
5.2), 2.5 vols 100% EtOH, mixed and incubated @ -20C for 30mins. Pelleted RNA @ 16,000g, 4C 30mins. Washed RNA with 1mL 70% EtOH (2x due to fear of residual salts from DNase Buffer). Pelleted RNA @ 16,000g, 4C, 15mins. Resuspended RNA in 45uL nuclease-free H2O. Sample was stored @ -80C (in “Sam’s RNA Box #1) until it could be DNased again.
Ran qPCR on DNased RNA from earlier today to verify removal of contaminating gDNA. Used C.gigas 18s primers (SR IDs: 156, 157). 0.5uL (50ng) of DNased RNA was used for testing. This corresponds, roughly, to the amount of sample that would be carried through to qPCR analysis of cDNA, assuming 1ug of RNA was used to make the cDNA (cDNA = 1000ng RNA/25uL = 40ng/uL, 1uL of cDNA in 25uL qPCR reaction). Positive control sample was ~25ng BB16 gDNA (from 20090519). Master mix calcs are here. Plate layout, cycling params, etc can be found in the qPCR Report (see Results). RNA was stored @ -80C in “Sam’s -80C Box”.
Results:
Ugh. Still gDNA present in this sample. Hmmmm. Will consider starting from original RNA, but will precipitate this sample again and treat again to see if I can get rid of that cursed gDNA.
Used EtOH precipitated BB01 RNA from 20110216 and followed Ambion’s “rigorous” protocol, utilizing a total of 2uL of DNAse. Briefly, samples were incubated @ 37C for 30mins, an additional 1uL of DNase was added to each sample, mixed and incubated for an additional 30mins @ 37C. After finishing protocol, samples were spec’d.
Results:
First reading had an air bubble and should be ignored. DNased RNA looks good, based on 260/280 ratios. As is usually the case for DNased RNA, the 260/230 ratios are on the low side. Will check DNased RNA for residual gDNA.
Due to residual gDNA contamination, will EtOH precipitate in order to treat with DNase again. Add 0.5 vols 3M NaAOc (pH = 5.2), 2.5 vols 100% EtOH, mixed and incubated @ -20C for 30mins. Pelleted RNA @ 16,000g, 4C 30mins. Washed RNA with 1mL 70% EtOH (2x due to fear of residual salts from DNase Buffer). Pelleted RNA @ 16,000g, 4C, 15mins. Resuspended RNA in 45uL nuclease-free H2O. Sample was stored @ -80C (in “Sam’s RNA Box #1) until it could be DNased again.
Ran qPCR on DNased RNA from earlier today to verify that it was free of contaminating gDNA. Used C.gigas 18s primers (SR IDs: 156, 157). 0.5uL (50ng) of DNased RNA was used for testing. This corresponds, roughly, to the amount of sample that would be carried through to qPCR analysis of cDNA, assuming 1ug of RNA was used to make the cDNA (cDNA = 1000ng RNA/25uL = 40ng/uL, 1uL of cDNA in 25uL qPCR reaction). Positive control sample was ~25ng BB16 gDNA (from 20090519). Master mix calcs are here. Plate layout, cycling params, etc can be found in the qPCR Report (see Results). RNA was stored @ -80C in “Sam’s -80C Box”.
Results:
There is residual gDNA in the BB01 sample. Will EtOH precipitate and treat again.
DNased BB09 was stored @ -80C in “Mac’s Gigas DNased RNA Box #1″ (on the top shelf) with the rest of the PROPS DNased RNA.
5ug of RNA was DNased using Ambion’s Turbo DNA-free kit, following the rigorous protocol (0.5uL of DNase for 30 mins then additional 0.5uL of DNase for 30mins). Calcs for DNase reactions are here. RNA was stored @ -80C in Shellfish RNA Boxes 4 and 5. Samples will be spec’d on Monday.
Results:
Overall, the RNA looks really good (based on OD 260/280 numbers). Not surprisingly, the OD 260/230 values for all samples dropped, likely due to the addition of the buffer (salts) used in the DNase reaction. Emma says she will check these samples for residual DNA.
–UPDATE (20110131)– Emma checked all DNased RNA samples on 20110131 using C.gigas 18s primers (SR ID: ?). She has not listed the results of the whether or not all samples are clean or if some still have residual gDNA carryover.
–UDPATE (20110201– Samples that appear to have residual gDNA carryover based on Emma’s qPCR on 20110131: Muscle C6, Gill 1hr C2 & E2.
Prepared cDNA using 1ug of RNA from each of the 3 pools (CA, MA, MAX) and processed according to Promega’s M-MLV protocol, using oligo dT primers. Calcs and master mix set up are here. Briefly, RNA was combined with oligo dT primers, denatured @ 70C for 5mins, immediately placed on ice for 2mins, mixed with RT master mix, incubated 1hr @ 42C, 3mins @ 95C, and then stored @ -20C.
Pooled 2ug of each sample in each group (MAX, CA, MA) for a total of 6ug of RNA (3 total samples), brought volume up to 50uL and DNased using Ambion’s Turbo DNA-free following the rigorous protocol. Calcs can be seen here. Spec’d:
Results:
All samples look pretty good. Oddly, the 260/280 ratios are absolutely perfect, despite the 260/280 ratios from each individual sample being less than stellar (see yesterday’s EtOH precipiation). Also of note is that the concentrations for all three samples are extremely close, reflecting the accuracy of the NanoDrop readings of each individual sample used for the pool as well as my pipetting. 
RNA was stored @ -80C in “Sam’s RNA Box #1.”
Recovered ~50uL from each sample which means each pool yielded ~3.85ug of RNA after DNase treatment. Will proceed with making cDNA from these three pools. In the interest of time (and the failure of our Opticon), I will not verify that these do NOT still contain gDNA (and, it’s pretty unlikely that they do).
Made a fresh, double batch (50uL rxn instead of 25uL) of cDNA according to Promega MMLV protocol using oligo dT primers. cDNA was put into a plate for faster qPCR loading. cDNA calcs and plate layout are here. Briefly, RNA and oligo dTs were combined, brought up to 37uL, heated @ 70C for 5mins and immediately placed on ice. RT master mix was made (RT master mix calcs are here), 13uL was distributed to each well. Samples were incubated @ 42C for 1hr and then 95C for 5mins.
UPDATE: cDNA plate was discarded 20120320 by SJW.
Set up PCR on recent Sepia cDNA and DNased RNA samples using both S. officianalis_rhodopsin_F, R primers & Sep_op_F2, R2 primers. After yesterday’s intirguing PCR results, we need to confirm that the DNased RNA is free of contaminating gDNA. Additionally, we want to excise bands from the cDNA samples for sequencing. PCR set up is here. RNA was prepped as though making cDNA; diluted 0.2ug of DNased RNA in a final volume of 25uL. Used 1uL of this for PCRs.
Rhodopsin primers require 3mM Mg2+ in the PCR rxn and the opsin primers require 2mM Mg2+ in the PCR rxn. 25mM Mg2+ was added as required and is shown on the PCR set up link above.
Results: n00b alert! The gel below is a repeat of yesterday’s PCR, except with DNased RNA samples added to verify no gDNA carryover. However, you’ll notice that the PCR results on the cDNA don’t look identical to yesterday’s PCR. Ugh.
Gel Loading (from left to right):
Opsin Primers (top half of gel), Rhodopsin Primers (same loading order, bottom half of gel)
RNA samples (left sides of gel), cDNA samples (right sides of gel)
1 – 100bp ladder
2 – retina
3 – fin
4 – 4th arm
5 – dorsal mantle center
6 – dorsal mantle side
7 – ventral mantle center
8 – ventral mantle side
9 – H2O
Loading is repeated in the above order for the cDNA, which is the right halves of the gel.
Well, the good news is that no signal is seen in the DNased RNA samples, thus confirming that there is no detectable gDNA carryover.
Opsin Primers
We see a band in the retina, fin & ventral mantle center samples as we did yesterday. However, we see a band in the 4th arm sample, which was not present yesterday. We also do NOT see a band in the ventral mantle side sample like we did yesterday. Negative controls are negative.
Rhodopsin Primers
We see a band in the retina and fin samples as we did yesterday. However, we no longer see the dual bands in the ventral mantle center as were seen yesterday. Negative controls are negative.
Bands were excised from the gel, placed in 1.5mL snap cap tubes and stored in the -20C in Sam’s “Purified Inserts” box.
Because of the lack of repeated results, I will repeat this PCR for a third time, with just the cDNA again, to see if I can duplicate one set of results…
