Leech egg-laying-like hormone: structure, neuronal distribution and phylogeny.
Cells immunoreactive to antisera specifically directed against Lymnaea stagnalis caudo dorsal cells egg-laying hormone (CDCH) or against alpha- and beta-peptides (CDCP), encoded on the egg-laying hormone precursor, were detected in central nervous system (CNS) of the rhynchobdellid leech Theromyzon tessulatum. A co-localization of the CDC-like hormone and CDC-like peptides was found in T. tessulatum as in L. stagnalis CNS. approximately 45 immunoreactive cells to the anti-CDCH were detected in leech brain but this number varies according to the stage of the animal life cycle, i.e. it reaches a maximum just before egg-laying while after it decreases to 2-3 cells. CDCH and alpha-CDCP epitopes recognized by anti-CDCH and anti-alpha-CDCP were contained in neurosecretory granules. Following an extensive purification, including HPGPC and reverse-phase HPLC, the CDC-like hormone contained in the T. tessulatum CNA was isolated. The sequence (GSGVSNGGTEMIQLSHIRERQRYWAQDNLRRRFLEK-amide) was established by a combination of automated Edman degradation, arginyl-endopeptidase digestion, electrospray mass spectrometry measurement and carboxypeptidase A treatment. The results demonstrate that the peptide recognized by the anti-CDCH in the leech CNS possesses 27.8, 37.2 and 47.2% sequence identity with Aplysia parvula, Lymnaea stagnalis and Aplysia californica ELH, respectively. This molecule was named the leech egg-laying-like hormone (L-ELH). The secondary structure prediction of the L-ELH and all mollusks ELH, revealed the existence of a conserved segment (segment 29-34) in a strong helicoidal bend that might be important for receptor recognition and/or activation. This finding constitutes the first biochemical characterization of an egg-laying hormone in other invertebrates than mollusks.
Salzet
M
M
Centre de Biologie Cellulaire, Laboratoire de Phylogénie Moléculaire des Annélides, EA DRED 1027, Université des Sciences et Technologies de Lille, Villeneuve d'Ascq, France. salzet@univ-lille1.fr
Verger-Bocquet
M
M
Vandenbulcke
F
F
Van Minnen
J
J
D000595:Amino Acid Sequence; D000818:Animals; D004268:DNA-Binding Proteins / Q000096:biosynthesis*; D004797:Enzyme-Linked Immunosorbent Assay; D005260:Female; D007150:Immunohistochemistry; D007447:Invertebrate Hormones / Q000032:analysis / Q000737:chemistry*; D007865:Leeches / Q000502:physiology*; D008195:Lymnaea; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D009474:Neurons / Q000502:physiology*; D010058:Oviposition; D010802:Phylogeny; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D014157:Transcription Factors
D004268:DNA-Binding Proteins; D007447:Invertebrate Hormones; D014157:Transcription Factors; C110168:Zfp91 protein, rat; C110167:caudo dorsal cell-like hormone, leech; C042422:ovulation hormone, Lymnaea