Fig. 3. Detection of synapsin I mRNA from freshly isolated hepatocytes by northern blot. Membrane was probed with a 3' end probe from rat brain synapsin I. In brain total RNA (2 µg, lanes 1,2), the synapsin I message was detected as two species (*), at 3.3 and 4.3 kb. The synapsin I mRNA was detected in hepatocytes total RNA (22 µg, lane 3) and poly(A) RNA (3.3 µg, lane 4) (** and ***) at 2.5-3.1 kb. Presence of synapsin I message has been confirmed in three independent preparations of hepatocyte poly(A) RNA. Lane 1, 10 day exposure; lanes 2-4, 5 day exposure. Position of size standards is indicated in kb. The square bracket indicates 28S rRNA.