Lamprey lecticans link new vertebrate genes to the origin and elaboration of vertebrate tissues

The evolution of vertebrates from an invertebrate chordate ancestor involved the new organs, tissues, and cell types. It was also marked by origin duplication gene families . If, how, these morphological genetic innovations are related is unresolved question in vertebrate evolution. Hyaluronan extracellular matrix (ECM) polysaccharide important for water homeostasis tissue structure. Vertebrates possess a novel family hyaluronan binding proteins called Lecticans , studies jawed (gnathostomes) have shown they function many cells tissues that unique to vertebrates. This raises possibility and/or expansion this helped drive novelties. In order better understand lectican family, its role novelties, we investigated phylogeny genomic arrangement, expression patterns all lecticans sea lamprey ( Petromyzon marinus ), jawless vertebrate. Though both P. gnathostomes each four our phylogenetic syntenic analyses most consistent with independent one more lineage. Despite likely gnathostome families, find highly conserved vertebrate-specific mesenchyme-derived tissues. We that, unlike gnathostomes, expresses paralogs distinct subpopulations head skeleton precursors, potentially reflecting ancestral diversity skeletal Together, observations suggest pre-duplication had complex pattern, functioned support mesenchymal histology, played • Both resulting lineage-specific duplications. lineages, lampreys gnathostomes. Lamprey genes cartilage populations, possibly set supported it facilitated type