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Leech egg-laying-like hormone: structure, neuronal distribution and phylogeny
M Salzet1, M Verger-Bocquet, F Vandenbulcke
1Centre 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
Brain Research. Molecular Brain Research
|December 5, 1997
Summary
Researchers identified a novel leech egg-laying-like hormone (L-ELH) in the leech Theromyzon tessulatum. This hormone shares sequence similarities with mollusk egg-laying hormones, suggesting conserved functions in invertebrates.
Area of Science:
- Neurobiology
- Comparative Endocrinology
- Invertebrate Zoology
Background:
- The egg-laying hormone (ELH) plays a crucial role in reproduction in mollusks.
- Caudo dorsal cells (CDC) in Lymnaea stagnalis produce ELH and related peptides.
- The presence and function of ELH-like molecules in other invertebrate phyla remain largely unexplored.
Purpose of the Study:
- To investigate the presence and biochemical characteristics of ELH-like molecules in the leech Theromyzon tessulatum.
- To determine the sequence and structural properties of the identified leech hormone.
- To compare the leech hormone with known mollusk ELHs.
Main Methods:
- Immunohistochemistry using antisera against Lymnaea stagnalis CDCH and CDCP.
- Purification of the leech CDC-like hormone using HPGPC and reverse-phase HPLC.
- Amino acid sequencing via automated Edman degradation, mass spectrometry, and enzymatic digestion.
Main Results:
- Cells immunoreactive to CDCH and CDCP antisera were detected in the leech CNS, with varying numbers depending on the reproductive cycle.
- A leech egg-laying-like hormone (L-ELH) was isolated and sequenced.
- L-ELH exhibited sequence identities of 27.8%, 37.2%, and 47.2% with ELHs from Aplysia parvula, Lymnaea stagnalis, and Aplysia californica, respectively.
- A conserved helical segment was predicted in L-ELH and mollusk ELHs, potentially involved in receptor binding.
Conclusions:
- This study provides the first biochemical characterization of an egg-laying hormone in an invertebrate outside of the Mollusca phylum.
- The findings suggest a conserved structural and functional role for ELH-like peptides in regulating reproduction across diverse invertebrate groups.
- The identified L-ELH represents a significant discovery in understanding the evolution of reproductive neurohormones.