Analysis of major sperm proteins in two nematode species from two classes, Enoplus brevis (Enoplea, Enoplida) and Panagrellus redivivus (Chromadorea, Rhabditida), reveals similar localization, but less homology of protein sequences than expected for Nematoda phylum

Major sperm proteins (MSPs) are a nematode-specific system of cytoskeletal required for amoeboid movement. A number MSP genes vary in different nematode species, but encoded protein sequences reveal high homology between these proteins. However, all studies localization and functions to date based exclusively on the representatives order Rhabditida belonging class Chromadorea, while MSP-driven movement Enoplea, another major clade phylum Nematoda is still unconfirmed. In this study, we documented presence MSPs enoplean Enoplus brevis (Bastian, 1865) (Enoplida) compared species with that chromadorean Panagrellus redivivus (Linnaeus, 1767) (Rhabditida). Then, analyzed putative both species. Our results indicate presented E. spermatozoa form filamentous structures after activation, which may be considered as evidence their motor similar those nematodes. We found show lower known rhabditids whose exhibit hyper-conservatism sequences. These reflect more distant evolutionary relationships Enoplea Chromadorea than exist within order. data need reevaluate current views evolution Nematoda.