Constitutively active PKA causes ectopic calcium spikes in DVB neurons and increases calcium spike duration.

<p>(A) A representative trace of the GCaMP3 fluorescence in the synaptic region of DVB neurons in transgenic worms expressing PKA[CA] (<i>vjIs102</i>) during two consecutive defecation cycles. An ectopic calcium spike in DVB neurons was observed, as indicated by the bracket. Note that the cycle length is longer than 50 seconds, likely due to <i>unc-13(s69)</i> mutation, which was used to immobilize the worms for calcium imaging (See <a href="http://www.plosgenetics.org/article/info:doi/10.1371/journal.pgen.1003831#s4" target="_blank">Materials and Methods</a> for details). (B) Representative traces of the GCaMP3 fluorescence in the synaptic region of DVB neurons in worms with the indicated genotypes. The observed pBoc step and Exp step are indicated by arrows and arrowheads, respectively. (C) Average frequency of ectopic calcium spikes in DVB neurons during a 250-second imaging period in wild type animals (0.0±0.00 events per 250 seconds, n = 10 animals) and <i>vjIs102</i> (2.4±0.69 events per 250 seconds, n = 11 animals). (D) and (E) the duration and amplitude of regular DVB calcium spikes and ectopic calcium spikes in wild type and PKA[CA] (<i>vjIs102</i>) animals. Means and standard errors are shown. Asterisks indicate significant differences from wild type: ** P<0.01, *** P<0.005 in Student's t-test. “n.s.” indicates no significant difference between indicated groups.