Well, the studies on the MHC in the fish and particularly the zebra fish showed very clearly and convincingly that the MHC doesn't have to be of the type as is present in mammals and it can be on a completely... organised completely differently. In particular the work of Jasna Bingulac-Popovic in my group demonstrated that the class I and class II genes do not need to be together. That in the zebra fish they can be class I in one chromosome and class II in other chromosomes, and that the same was true for the so-called class III loci, which then Holger...

[Q] Sültmann

Holger Sültmann demonstrated were scattered all over the genome. So these studies indicated that there is no need for the genes to be together and that is not the reason why they are together in mammals, again supporting the view that this situation in mammals arose by chance and had, as far as could be said, no functional significance. These studies then led us to the questions of how the immune system in general evolved. The original opinion was that there are two kinds of immune system. One requires the participation of the MHC that is a receptor and the immunoglobulins and they were the basic molecules and that came to be referred to by various names, but most often as an adaptive immune system, and it was originally believed that this adaptive immune system is present in all animals practically. That MHC and the immunoglobulins will be found in other non-vertebrate species. Well, again there was... that was a belief that was not based on any specific data... on data that actually turned out to be not correct in some cases, and so I proposed that actually the system is not general for the entire animal kingdom but it's... that it arose with vertebrates, that the adaptive immune system is restricted to vertebrates. At that time we didn't know whether it would be all vertebrates or just a group of vertebrates, but my argument was that it would not be found in non-vertebrates.