Guanine

Yeast cells with BY4741 genetic background (MATa his3Δ1 leu2Δ0 met15Δ0 ura3Δ0) were grown in 10 mL CSM minimal media containing 2% glucose. Four different treatment/growth conditions were used: minimal media containing (i) 10 µM DMSO (American Bio AB00435), (ii) 10 µM DMSO and 10 µM mycophenolic acid (Sigma M5255), (iii) 10 µM DMSO and 10 µM guanine (Sigma–Aldrich G11950) and 10 µM mycophenolic acid, (iv) 10 µM guanine. Cells were grown for 18 h to a final density (OD₆₀₀) between 0.1 and 0.25. Cells were then diluted to 50 cells/μL for the final yeastDrop-Seq cell-collection using the microfluidic chip.
Doubling time of cells in each treatment condition was calculated as follows: ${\mathrm{OD}}_f={\mathrm{OD}}_i\times 2^{\frac{\mathrm{\Delta }t}{t_d}}\to {\log }_2\frac{{\mathrm{OD}}_f}{{\mathrm{OD}}_i}=\frac{\mathrm{\Delta }t}{t_d}\to t_d=\frac{\mathrm{\Delta }t}{{\log }_2\frac{{\mathrm{OD}}_f}{{\mathrm{OD}}_i}}$ where: ${\mathrm{OD}}_f={\mathrm{OD}}_{600}\mathrm{final}$
OD_i = OD₆₀₀ initial
$\mathrm{\Delta }t$  = elapsed culture time (18 h)
$t_d$  = calculated doubling time
Based on two-point cell density measurements, we found that the doubling time for MPA-treated cells was 187.8 min, for DMSO-treated cells was 130 min, for guanine-treated cells was 130 min, and for GM-treated cells was 158.9 min.

The neurotransmitters and metabolites tested were acetamidophenol, catechol, L-DOPA, dopamine, vanillylamine, homovanillic acid, norepinephrine, resorcinol, vanillic acid (all from Aldrich Chemical, Milwaukee, WI, USA), and uric acid (Fisher Scientific). The working solution was prepared in universal buffer with a concentration of 1.12–2.04 ppm (approximately 1 × 10⁻⁵ M) for each of the 10 compounds listed above.
The second class of analytes was nucleic acids and heterocyclic bases including adenine, adenosine, cytidine, cytosine, guanine, guanosine, thymidine, and uridine (all from Aldrich Chemical, Milwaukee, WI, USA). The working solution was prepared in universal buffer with a concentration of 56–204 ppm (approximately 5.00 × 10⁻⁴ M) for each of the eight analytes in this group.
The capsaicinoids used were capsaicin, dihyrocapsaicin, and N-vanillylnonanamide (VANA) (all from Sigma Chemical, St. Louis, MO, USA). The working solution was prepared in acetonitrile with a concentration of 148–152 ppm (approximately 5.00 × 10⁻⁴ M) for each of the three analytes listed above.

Silver nitrate (anhydrous, 99.999%), sodium borohydride (powder, ≥98.0%), adenine, guanine, thymine, cytosine, sodium hydroxide and poly(ethylene glycol) (average M_n 3,350, powder), avidin, rhodamine B, ninhydrin and glycine were purchased from Aldrich and used without further purification. 12mer polycytosine was obtained from Integrated DNA Technologies. Fisherfinest™ Premium Cover Glasses were purchased from Fisher Scientific and used without further treatment. TEM grids (Carbon Grid Type-A, 300Mesh, Cu) were purchased from TedPella. Ultrapure (Nanopure system) filtered water with a resistivity 18.2 MΩ cm was used in all experiments.