A full-length transcript encoding a functional type II GnRH receptor was cloned from the pituitary of the sea lamprey, Petromyzon marinus. The current study is the first to identify a pituitary GnRH receptor transcript in an agnathan, which is the oldest vertebrate lineage. The cloned receptor retains the conserved structural features and amino acid motifs of other known GnRH receptors and nota...

The vertebrate jaw is a mandibular-arch derivative, and is regarded as the synapomorphy that defines the gnathostomes. Previous studies (Kuratani et al., Phil. Trans. Roy. Soc. 356:15, 2001; Shigetani et al., Science 296:1319, 2002) have suggested that the oral apparatus of the lamprey is derived from both the mandibular and premandibular regions, and that the jaw has arisen as a secondary narr...

Structure and vitamin A-storage of the mesangial cells in the lamprey kidney are documented using the gold chloride method, fluorescence histochemistry and electron microscopy. Abundant lipid droplets in the cytoplasm of the mesangial cells release intense, but quickly fading vitamin A-fluorescence under a fluorescence microscope and react with gold chloride. Characteristic tubular invagination...

1. Lamprey fibrinopeptide B is a relatively large peptide made up of about 40 amino acid residues. The peptide is highly electronegative, containing a large number of aspartic acid residues and a tyrosine O-sulphate residue. 2. The amino acid sequence of the first 18 residues from the N-terminal end of fibrinopeptide B has been established. The C-terminal ends with the sequence Val-Arg. Fibrino...

Lampreys, one of the two surviving groups of ancient vertebrates, have become important models for study in diverse fields of biology. Lampreys (of which there are approximately 40 species) are being studied, for example, (a) to control pest sea lamprey in the North American Great Lakes and to restore declining populations of native species elsewhere; (b) in biomedical research, focusing partic...

Lymphocyte-like cells in the intestine of the sea lamprey, Petromyzon marinus, were isolated by flow cytometry under light-scatter conditions used for the purification of mouse intestinal lymphocytes. The purified lamprey cells were morphologically indistinguishable from mammalian lymphocytes. A cDNA library was prepared from the lamprey lymphocyte-like cells, and more than 8,000 randomly selec...

The Caspian Sea is the world’s largest inland sea. Physiographically it is unique. It is the most productive body of water in the world1 and the only one that preserves the geno-fund of the sturgeon, the source of almost all the black caviar produced. About 10 million people live around the Caspian Sea and the occupations of many of them are connected with the sea, and first of all with fishing...

The sea lamprey is a basal, jawless vertebrate that possesses many neural crest derivatives, but lacks jaws and sympathetic ganglia. This raises the possibility that the factors involved in sympathetic neuron differentiation were either a gnathostome innovation or already present in lamprey, but serving different purposes. To distinguish between these possibilities, we isolated lamprey homologu...

Three lamprey species occur in Ireland: sea lamprey, Petromyzon marinus (L.), river lamprey, Lampetra fluviatilis (L.) and brook lamprey, Lampetra planeri (Bloch). All three species are listed under Annex II of the EU Habitats Directive (Directive 92/43/EEC), thereby requiring member states to designate Special Areas of Conservation (SACs) for their protection. The juvenile or ammocoete stages ...

Receiver bias models suggest that a male sexual signal became exaggerated to match a pre-existing sensory, perceptual or cognitive disposition of the female. Accordingly, these models predict that females of related taxa possessing the ancestral state of signalling evolved preference for the male trait in a non-sexual context. We postulated that female preference for the male-released bile alco...