| OCR Text |
Show 19 cells (Collins et al., 2010). These cells are most likely the planarian Smed-GnRH releasing neurons. A systematic effort to analyze the functions of a genome-wide collection of the GPCRs by whole-mount in situ hybridization (Pearson et al., 2009) and double stranded RNA-mediated genetic interference (RNAi) (Sanchez Alvarado and Newmark, 1999) is currently underway in Dr. Phillip A. Newmark's laboratory. The processed hormonal peptide sequence of S. mediterranea GnRH is likely pQSYHFSNDWLPG-amide, which shares several features universal to vertebrate and invertebrate GnRHs: the N-terminal pyroglutamyl; the C-terminal amidated glycine; twelve amino acids in length (the invertebrate feature); evolutionarily conserved amino acids at corresponding positions (e.g., H, S, and P to both vertebrates and invertebrates, Y, N, and W to the invertebrates). As our primary goal was to address whether or not the S. mediterrnea GnRH peptide promotes sexual reproduction, one approach is to synthesize the peptide and subject it to the worms to examine whether there would be an increase of egg and hatchling numbers. Two peptides were synthesized for this purpose. One was the octopus GnRH peptide. The other was the planarian GnRH peptide, which has high similarity to the octopus peptide except for three amino acids. While nothing was known about the sexual reproduction of S. mediterranea in captivity at the moment, a closely related S. polychroa, on the other hand, laid eggs robustly in the same culturing conditions. Therefore, the rationale was that sexually productive S. polychroa might reveal the effect of GnRH peptide more readily as the downstream factors of GnRH signaling are likely active. Hence, two boxes of S. polychroa were set up for the experiment with 20 worms each. One box of worms received the hormone solution. The other served as a negative control. Eggs were |
