. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Figure 6. Effects of pQFYRFamide on a Cl neuron from the cere- bral ganglia of Hcli\ (A) Examples of the currents evoked by the peptide at different holding potentials (Vh). In the top record, the voltage was periodically stepped to -50 mV to monitor the conduc- tance: note that the current pulses in response to the -5 mV steps are about twice as large at the peak of the response as in the control. (B) Relationship between peak evoked current and holding potential for responses in physiological solutions containing
. The Biological bulletin. Biology; Zoology; Biology; Marine Biology. Figure 6. Effects of pQFYRFamide on a Cl neuron from the cere- bral ganglia of Hcli\ (A) Examples of the currents evoked by the peptide at different holding potentials (Vh). In the top record, the voltage was periodically stepped to -50 mV to monitor the conduc- tance: note that the current pulses in response to the -5 mV steps are about twice as large at the peak of the response as in the control. (B) Relationship between peak evoked current and holding potential for responses in physiological solutions containing normal (5 circles) or reduced ( mM, squares) concentrations of potassium. The data shown in the graph were taken from an experiment on a singled neu- ron. A second experiment gave the same result. Discussion We have sequenced the 5' end of the cDNA encoding the FMRFamide precursor of Helix aspersa. and so the entire sequence is now complete. The general organiza- tion of this precursor is similar to that of the two other completely sequenced FMRFamide precursors: Lym- naea stagnalis (reviewed by Benjamin and Burke, 1994) and Aplysia californica (see Taussig and Scheller, 1986). The similarity is manifest in both the splicing pattern and in the linear arrangement of landmark sequences in the precursor. The mRNA encoding the FMRFamide precursor in all three species is composed of at least two exons, and in all three the splice junction is in a roughly similar posi- tion. In both Lymnut'ii and Helix the first exon of the FMRFamide precursor is alternatively spliced to give an- other neuropeptide precursor (that of the FLRFamide- related heptapeptides), but no alternatively spliced prod- uct has ever been found in Aplysin. Vh= -45 mV pQFYRFa. Vh= -80 mV \r pQFYRFa j nA 10s Figure 7. Comparison of currents evoked by FMRFamide and pQFYRFamide in the C2 neuron. At a holding potential of -45 mV. pQFYRFamide evoked an outward current, whereas FMRFamide evoked a fast inward c
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Keywords: ., bookauthorlilliefrankrat, booksubjectbiology, booksubjectzoology
