Characterization and diversity of major histocompatibility complex class II DQB gene in brown bear (Ursus arctos)

Glavni sustav tkivne podudarnosti (engl. major histocompatibility complex, MHC) ključan je u pokretanju obrambenih mehanizama kralježnjaka, a smatra se da su neki od lokusa MHC među najpolimorfnijim u kralježnjaka. Raznolikost gena MHC utječe na sposobnost populacije da se obrani od različitih patogena. Varijabilnost lokusa MHC održava ravnotežna selekcija, koju karakterizira veći broj raznolikih alela u populaciji. Geni MHC pokazali su se kao dobar marker za proučavanje adaptivne evolucije vrsta i populacija. Mrki medvjed (Ursus arctos) pripada redu Carnivora (zvijeri), porodici Ursidae (medvjedi) i rodu Ursus. Ovo je prvo ovakvo istraživanje u Hrvatskoj. Kod 30 uzoraka tkiva medvjeda pronađeno je šest alela lokusa DQB. Od njih su tri alela bila nova: RH102_7_M13F, Urth DQB*0401var i Urth DQB*0401vv. Ostali pronađeni aleli poznati su iz prethodnih istraživanja mrkih medvjeda. U osam jedinki sam identificirala po tri alela DQB lokusa, dok sam u 22 jedinke identificirala po dva alela, što ukazuje na to da je lokus DQB dupliciran barem u dijelu jedinki populacije mrkog medvjeda iz Hrvatske.Major histocompatibility complex (MHC) plays a major role in initiating defense mechanisms of vertebrates. It is believed that some of the MHC loci are the most polymorphic invertebrates. The variability of MHC genes affects population`s ability to defend itself fromvarious pathogens.The variability of the MHC loci is maintained by the balancing selection, which is characterized by a larger number of divergent alleles in the population. MHC genes proved to be a good marker for the study of adaptive evolution of the species and populations. Brown bear (Ursus arctos) belongs to the order Carnivora (carnivores), family Ursidae (bears) and gene Ursus. From 30 samples of bear tissue I found six aleles of the gene DQB. Three alele were new: RH102_7_M13F, Urth DQB*0401var and Urth DQB*0401vv. Other three were known from the previous research. In eight individuals I identified three alleles of DQB locus, while in 22 individuals I identified two alleles, indicating that the DQB locus was duplicated at least in the part of the brown bear populations from Croatia