The field collection is over but fun continues
in the lab! Here, in the lab, is here we spend most of our time. After sampling
fish tissue, the next step is to extract the total RNA content of each
individual sample. In 6 days, our brave and hard working undergrad students,
Paula and Maithê, have extracted RNA and the DNA from 88 fish livers.
The RNA will be used in our project. It is from
these molecules that we will be able to sequence our favorite genes, CYP1A and
AHR. The DNA will be sent to our collaborators at the National Museum of Rio de
Janeiro for phylogenetics studies. At an appropriate moment, these two pieces
of data will come together and eventually clarify some of the ecological roles
of AHR/CYP1A in the evolution of loricariids.
RNA extraction is tricky! RNAses, enzymes that
degrades RNA, are omnipresent! They are just every and anywhere; on your
fingers, on your hair, on your saliva, on the dust (oww there are tons of that
on the dust!), air etc! If you don’t take the necessary precautions, your
sample will get contaminated, your RNA degraded and your time & patience
lost. The thing is that you just get to know whether your RNA preparation is
good or not at the very end of the process, when you run your sample in an
agarose gel and actually see the RNA. Well truly you don’t see the RNA but
instead the light emitted by a molecule, ethidium bromade, attached to it. The
expected (or the good) result is to see two bands on the gel upon illuminating
it with U.V. light. These two bands correspond to two of the ribosomal RNA
molecules, the 18S and the 28S. Now, guess what did we get? No, I am not giving
the answer! Check the photo of some of our extractions bellow and get to your
own conclusions!
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