The lamprey Petromyzon marinus (P. marinus), is an agnatha (jawless) vertebrate belonging to the group of Petromyzontidae, which includes less than forty species. It has a cord, a rounded mouth with spikes, a cartilaginous skeleton and rudimentary vertebrae. Its morphology is reminiscent of that of the eel (elongated body without scales), but with a much larger size (70 cm-1 m). This species has a wide geographical distribution in Europe and North America and is easy to maintain in the laboratory during spawning periods. Oviposition is very abundant but seasonal, and embryos can be maintained in the laboratory until the prolapsed stage.
Due to the complexity of the life cycle (migratory species) and the length of the larval stages (several years), this species is not currently farmed. It is currently the reference model for cyclostomata (hagfishes and lampreys), the sister group of jawed vertebrates. This phylogenetic position makes it a key species in understanding the origin of vertebrates, and more generally, in any systematic comparative approach at the vertebrate scale. Possible functional approaches in this species include the loss of gene function via injection of morpholino antisense oligonucleotides and transient expression of reporter genes or overexpression vectors.
Fertilization is external.
Spawning is seasonal and very abundant since a female can produce up to 10,000 eggs per clutch. The generation time is quite long, 6 to 7 years. Spawning takes place in the spring in river environments, following a spawning migration from estuaries.
Development includes an embryonic phase (6 weeks) and a larval phase (5 years), after which metamorphosis takes place followed by a return to the sea for the post-metamorphic animals.
Genomic databases :
Database of 150 000 embyonic EST, collection of corresponding clones, available on request from S. Mazan
The most commonly used is Tahara Y. 1988. Zoological Science 5 :109-118 (table compiled for Lampetra reissneri but also valid for P. marinus)
« The sea lamprey Petromyzon marinus genome reveals the early origin of several chemosensory receptor families in the vertebrate lineage. », Libants S. et al., BMC Evol Biol., 2009
« Dual nature of the adaptive immune system in lampreys. », Guo P. et al., Nature, 2009
« Modularity, comparative embryology and evo-devo: developmental dissection of evolving body plans. », Kuratani S., Dev Biol., 2009
« Neurodevelopment genes in lampreys reveal trends for forebrain evolution in craniates. », Guérin A. et al., PLoS One., 2009
« Cyclostome studies in the context of vertebrate evolution. », McCauley DW. et al., Zoolog Sci., 2008
« Ancient evolutionary origin of the neural crest gene regulatory network. », Sauka-Spengler T. et al., Dev Cell., 2007