Figure 2. tRNA fragments are regulated by epileptiform activity in hippocampal neurons.

(A) Primary mouse hippocampal neurons were incubated with 5 μM FLUO4 for 45 minutes at 37°C and imaged at 5 Hz. Scale bar: 40 μm. (B) Representative FLUO4 traces are shown for neurons in 1 mM Mg (Mg⁺, upper panel) or 0 mM Mg (Mg^–, lower panel). Following 2 hours in Mg⁺ or Mg^– media, the media were collected and total RNA extracted. Both intracellular (C) and extracellular (D) tRNA fragment levels were lower following culture in Mg-free media, in which extracellular 5′GluCTC and 5′GlyGCC levels were significantly lower. *P < 0.05, by Students t test. In C and D, individual data points are plotted, with the mean indicated in red and error bars ± SEM. n = 15–16 replicates from 5 independent preps.