Invasion of the European River Lamprey Lampetra fluviatilis in the Upper Volga

The European river lamprey came to the Upper Volga from the Baltic Sea most probably via a system of shipways developed in the 18th and 19th centuries. The Vyshnii Volochek, Tikhvin, and Mariinskaya water systems are possible invasion pathways for this species. Dispersal and colonization of the Caspian Basin was likely a combination of upstream and downstream migrations. Analysis of museum and our own samples showed that lamprey possibly migrated upstream (for spawning) along rivers of the Baltic Basin until they reached the watershed boundary from which they could disperse downstream (in the juvenile period) into rivers of the Caspian Basin. Dispersal in the Volga River could occur in accordance with the migration cycle of this opportunistic lamprey species and lead to the present distribution. Key features (dentition and number of trunk myomeres) showed that lamprey from the studied area are similar to lampreys from the Baltic basin, although specimens in each population have their own peculiarities in morphology (size and coloration). Genetic data (Cyt-b) support the idea of a relatively recent invasion of lamprey into the Upper Volga. The haplotype, found in three rivers, is one of the most widespread in Europe and is found along the supposed route of invasion

The Molecular Mechanism of Body Axis Induction in Lampreys May Differ from That in Amphibians

Lamprey homologues of the classic embryonic inducer Noggin are similar in expression pattern and functional properties to Noggin homologues of jawed vertebrates. All noggin genes of vertebrates apparently originated from a single ancestral gene as a result of genome duplications. nogginA, nogginB and nogginC of lampreys, like noggin1 and noggin2 of gnathostomes, demonstrate the ability to induce complete secondary axes with forebrain and eye structures when overexpressed in Xenopus laevis embryos. According to current views, this finding indicates the ability of lamprey Noggin proteins to suppress the activity of the BMP, Nodal/Activin and Wnt/beta-catenin signaling pathways, as shown for Noggin proteins of gnathostomes. In this work, by analogy with experiments in Xenopus embryos, we attempted to induce secondary axes in the European river lamprey Lampetra fluviatilis by injecting noggin mRNAs into lamprey eggs in vivo. Surprisingly, unlike what occurs in amphibians, secondary axis induction in the lampreys either by noggin mRNAs or by chordin and cerberus mRNAs, the inductive properties of which have been described, was not observed. Only wnt8a mRNA demonstrated the ability to induce secondary axes in the lampreys. Such results may indicate that the mechanism of axial specification in lampreys, which represent jawless vertebrates, may differ in detail from that in the jawed clade