mRNA Isolation

Isolating mRNA from surgical samples

Published

Oct 3, 2023

Protocol

Lyse samples and separate phases

  1. Add \(0.5\ mL\) of TRIzol into an Eppendorf tube containing each sample
  2. Transfer the contents to a mortar. Add \(50\ mL\) of liquid nitrogen (\(LN_2\)) and grind the sample. Repeat with additional \(LN_2\), as needed, grinding the sample into a fine powder.
  3. Transfer the Sample + Trizol powder into a fresh Eppendorf.
  4. Add \(0.3\ mL\) of TRIzol into each Eppendorf.
  5. Pipette mix to homogenize
  6. Incubate for 5 min for complete dissociation of the nucleoprotein complex
  7. \(0.25\ mL\) of chloroform per \(1\ mL\) of Trizol
  8. Incubate for 2-3 min
  9. Centrifuge the samples for 15 min at \(12,000g\) at \(4^{\circ}C\)
  10. Transfer the clear upper phase containing RNA to a fresh Eppendorf tube. Ensure you do not contaminate the aqueous phase by touching the whitish, DNA containing interphase.
  11. If desired, you can store the remainder of Trizol phase containing DNA and Protein at \(-80^{\circ}C\)

RNA Isolation

  1. Add \(0.5\ mL\) of Isopropanol to the aqueous phase per 1 mL of Trizol used
  2. Incubate for 10 min
  3. Centrifuge the samples for 15 min at \(12,000g\) at \(4^{\circ}C\)
  4. Visualize the total RNA precipitate at the bottom of the tube (whitish, gel-like pellet)
  5. Discard the supernatant with a pipette
  6. Wash pellet with \(1\ mL\) of cold (\(4^{\circ}C\)) 75% Ethanol per 1mL of Trizol used
  7. Vortex briefly
  8. Centrifuge the samples for 5 min at \(7,500g\) at \(4^{\circ}C\)
  9. Discard the supernatant by inverting the tube in one fluid motion, being careful to not disturb the pellet
  10. Use a vacuum centrifuge to dry the remaining amount of supernatant (~ 5 min)
  11. Resuspend the pellet in \(32\ \mu L\) of RNAse-free water (molecular grade water)
  12. Pipette mix to ensure complete resuspension

Determine the RNA Yield: Nanodrop

  1. Configure the nanodrop to export to USB CSV
  2. Pipette \(1.5\ \mu L\) of each sample into the nanodrop to measure the concentration
  3. Save the sample, giving it a name ##### RNA to USB CSV (##### is the 5 digit randomized study subject identification number)
  4. Paste the nanodrop readings into the corresponding CSV file / Excel file
---------------------------------------------------------------------------
KeyError                                  Traceback (most recent call last)
Cell In[2], line 24
     21     os.environ['is_docker'] = 'False'
     22     os.environ['repo_root'] = "/home/pranav/work/pranavmishra90/research-reference"
---> 24 os.chdir(os.environ['repo_root'])
     26 # Load the subject's nanodrop readings
     28 subject_nanodrop = pd.read_csv(f'protocols/molecular-biology/PCR/demo_nanodrop.csv')

File <frozen os>:709, in _Environ.__getitem__(self, key)
    706     value = self._data[self.encodekey(key)]
    707 except KeyError:
    708     # raise KeyError with the original key value
--> 709     raise KeyError(key) from None
    710 return self.decodevalue(value)

KeyError: 'repo_root'
---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
Cell In[3], line 1
----> 1 Markdown(tabulate(subject_nanodrop[['Date', 'Time', 'Sample Number', 'A230', 'A260', 'A280', 'A320',
      2        'A260/A230', 'A260/A280', 'Concentration', 'Sample Name']], headers=['Date', 'Time', 'Sample Number', 'Sample Name', 'A230', 'A260', 'A280', 'A320', 'A260/A230', 'A260/A280', 'Concentration'],showindex="never", numalign='center', stralign='center', tablefmt="grid"))

NameError: name 'subject_nanodrop' is not defined
Table 1: Select nanodrop readings

Conversion to cDNA

---------------------------------------------------------------------------
NameError                                 Traceback (most recent call last)
Cell In[4], line 1
----> 1 lowest_rna_concentration = min(subject_nanodrop['Concentration'])
      3 rna_to_be_used = target_total_rna_ng_ul / lowest_rna_concentration
      5 cdna_conversion = subject_nanodrop

NameError: name 'subject_nanodrop' is not defined
<>:1: SyntaxWarning: "\m" is an invalid escape sequence. Such sequences will not work in the future. Did you mean "\\m"? A raw string is also an option.
<>:3: SyntaxWarning: "\m" is an invalid escape sequence. Such sequences will not work in the future. Did you mean "\\m"? A raw string is also an option.
<>:1: SyntaxWarning: "\m" is an invalid escape sequence. Such sequences will not work in the future. Did you mean "\\m"? A raw string is also an option.
<>:3: SyntaxWarning: "\m" is an invalid escape sequence. Such sequences will not work in the future. Did you mean "\\m"? A raw string is also an option.
/tmp/ipykernel_2875/3255309191.py:1: SyntaxWarning: "\m" is an invalid escape sequence. Such sequences will not work in the future. Did you mean "\\m"? A raw string is also an option.
  display(Markdown(f" Our target concentration of cDNA is {target_total_rna_ng_ul} $\\frac{{ng}}{{\mu L}}$."))
/tmp/ipykernel_2875/3255309191.py:3: SyntaxWarning: "\m" is an invalid escape sequence. Such sequences will not work in the future. Did you mean "\\m"? A raw string is also an option.
  display(Markdown(f"The least concentration of any sample is {lowest_rna_concentration} $\\frac{{ng}}{{\mu L}}$. To obtain the target concentration, we will need to use {round(rna_to_be_used, 2)} $\\mu L$ of the RNA previously isolated."))

Our target concentration of cDNA is 1500 \(\frac{ng}{\mu L}\).

/tmp/ipykernel_2875/3255309191.py:1: SyntaxWarning: "\m" is an invalid escape sequence. Such sequences will not work in the future. Did you mean "\\m"? A raw string is also an option.
  display(Markdown(f" Our target concentration of cDNA is {target_total_rna_ng_ul} $\\frac{{ng}}{{\mu L}}$."))
/tmp/ipykernel_2875/3255309191.py:3: SyntaxWarning: "\m" is an invalid escape sequence. Such sequences will not work in the future. Did you mean "\\m"? A raw string is also an option.
  display(Markdown(f"The least concentration of any sample is {lowest_rna_concentration} $\\frac{{ng}}{{\mu L}}$. To obtain the target concentration, we will need to use {round(rna_to_be_used, 2)} $\\mu L$ of the RNA previously isolated."))
```{=html}

————————————————————————— NameError Traceback (most recent call last) Cell In[5], line 3 1 display(Markdown(f Our target concentration of cDNA is {target_total_rna_ng_ul} $\frac