Significant intraindividual variation in the sequence of the 18S rRNA gene is unusual in animal genomes. In a previous study, multiple 18S rRNA gene sequences were observed within individuals of eight species of sturgeon from North America but not in the North American paddlefish, Polyodon spathula, in two species of Polypterus (Polypterus delhezi and Polypterus senegalus), in other primitive f...

Abstract Sturgeon and paddlefishes (Acipenseriformes) are cultured worldwide for commercial conservation purposes. Over the past decade, we have learned many sturgeon culture programs experience spontaneous autopolyploidy, or generation of triploidy without management intervention. Spontaneous autopolyploidy has been shown to negatively impact physiology, reproductive development fertility stur...

Fish are the most numerous group of vertebrates in the world and their anatomy is still not completely studied. This article is aimed to present the morphological study of swimbladder in different species of ray-finned fish which have industrial value namely Russian sturgeon, American paddlefish (order Acipenseriformes), rainbow trout (order Salmoniformes), northern pike (order Esociformes), za...

BACKGROUND Equipped with an effective predatory feeding mechanism enhanced by large and sharp teeth, pointed snout and elongate body, saurichthyiform fishes are considered common fish-eaters in the early Mesozoic aquatic ecosystems. Additionally, because of the similar body plan across species, saurichthyiforms are also regarded evolutionally conservative, with few morphological and ecological ...

A new species of parasitic nematode, Cystoopsis atractostei (Trichinelloidea: Cystoopsidae), is described based on female specimens recovered from the subcutaneous tissue of the tropical gar, Atractosteus tropicus Gill (Lepisosteiformes: Lepisosteidae), from 2 localities (Canal Nueva Esperanza and Canal Tabasquillo) of the Pantanos de Centla Biological Reserve, State of Tabasco, southeastern Me...

Abstract Ray-finned fishes comprise nearly half of extant vertebrate species and include several ancient lineages with fossil records that stretch over 200 Myr in time. One these old clades, the sturgeons paddlefishes, is distributed across Northern Hemisphere includes some largest known freshwater fishes. Yet, record this lineage (Acipenseriformes) poor compared to similarly ray-finned fish cl...