The candidate Fu/HC gene in Botryllusschlosseri (Urochordata) and ascidians' historecognition - An oxymoron?

► The fusibility locus (Fu/HC) of Botryllus was claimed to be isolated. ► Queries have emerged about discrepancies in original results. ► Cloning, ISH, sq-PCR and incongruence between fusibility and Fu/HC polymorphism also negated original results. ► Conclusion: the animal's histocompatibility properties are not signaled by the cloned gene.