GSM5499532: SM-GE63U_S075_E1-50; Mus musculus; RNA-Seq
We isolated single cells as previously described (Hempel et al., 2007; Sugino et al., 2006; Tasic et al., 2016) with modifications. We mostly employed layer-enriching dissections, with focus on a single layer. Broader dissections (no layer enrichment or multiple layers combined) were employed for lines which label small numbers of cells, in order to facilitate isolation of sufficient number of cells. We updated our ACSF formulation to consist of CaCl2 (0.5 mM), glucose (25 mM), HCl (96 mM), HEPES (20 mM), MgSO4 (10 mM), NaH2PO4 (1.25 mM), myo-inositol (3 mM), N-acetylcysteine (12 mM), NMDG (96 mM), KCl (2.5 mM), NaHCO3 (25 mM), sodium L-ascorbate (5 mM), sodium pyruvate (3 mM), taurine (0.01 mM), thiourea (2 mM), and bubbled with carbogen gas (95% O2 and 5% CO2). For samples collected after 12/16/2016, the ACSF formulation also included trehalose (13.2 mM). Mice were anesthetized with isoflurane and perfused with cold carbogen-bubbled ACSF. The brain was dissected, submerged in ACSF, embedded in 2% agarose, and sliced into 250-µm coronal sections on a compresstome (Precisionary). Enzymatic digestion, trituration into single cell suspension, and fluorescence-activated cell sorting (FACS) of single cells were carried out as previously described (Tasic et al., 2016). Cells were sorted into 8-well strips containing lysis buffer from SMART-Seq v4 kit with RNase inhibitor (0.17 U/µl), immediately frozen on dry ice, and stored at -80°C. We used the SMART-Seq v4 Ultra Low Input RNA Kit for Sequencing (Takara Cat#634894) to reverse transcribe poly(A) RNA and amplify cDNA according to the manufacturer's instructions. We performed reverse transcription and cDNA amplification for 18 PCR cycles in 8-well strips, in sets of 12-24 strips at a time. At least 1 control strip was used per amplification set, which contained 4 wells without cells and 4 wells with 10 pg control RNA. Control RNA was either Mouse Whole Brain Total RNA (Zyagen, MR-201) or control RNA provided in the SMART-Seq v4 kit. All samples proceeded through NexteraXT DNA Library Preparation (Illumina FC-131-1096) using NexteraXT Index Kit V2 Set A (FC-131-2001). NexteraXT DNA Library prep was performed according to manufactorer's instructions except that the volumes of all reagents including cDNA input were decreased to 0.4× or 0.5× by volume. Details are available in Documentation on the Allen Institute data portal at: http://celltypes.brain-map.org/.