Variability of major histocompatibility complex class II genes in the golden jackals (Canis aureus) from Israel

Abstract

Geni glavnog sustava tkivne podudarnosti (MHC) ključna su komponenta imunološkog sustava kod sisavaca te su i važan molekularni marker adaptivne genetičke raznolikosti u divljim populacijama životinja. Veća raznolikost MHC gena unutar populacije povećava izglede populacije za obranu od patogena i parazita, a time i izglede za dugoročno preživljavanje. Čagalj (Canis aureus) pripada porodici Canidae (psi), podred Caniformia, redu Carnivora (mesojedi). Do sada nema objavljenih istraživanja raznolikosti MHC gena ove vrste. Cilj ovog diplomskog rada je odrediti razinu raznolikosti DQA, DQB i DRB gena skupine II MHC sustava u čagljeva iz Izraela. Iz 30 uzoraka uške čaglja, postupcima izolacije DNA, PCR metodom, elektroforezom, sekvenciranjem i molekularnim kloniranjem, pronađena su tri alela na DQA lokusu, pet alela na DQB lokusu i četiri alela na DRB lokusu. Našli smo jedan novi jedinstveni alel na DRB lokusu (DRB1*04802var). Ostali pronađeni aleli poznati su iz prethodnih istraživanja na ostalim vrstama porodice pasa, što potvrđuje postojanje trans-specijskog polimorfizma. DQB i DRB lokusi pokazuju veliku raznolikost alela i velike evolucijske udaljenosti te visok omjer nesinonimnih supstitucija naspram sinonimnih, što potvrđuje pretpostavku djelovanja pozitivne selekcije na te lokuse.The genes of major histocompatibility (MHC) system are a key component of the immune system in mammals and are important molecular markers of adaptive genetic diversity in wild animal populations. Greater diversity of MHC genes within the population increases the chances of defence against pathogens and parasites, and thus the prospects for long-term survival. Golden jackal (Canis aureus) belongs to the family Canidae (dogs), suborder Caniformia, order Carnivora (carnivores). So far there are no published studies of MHC gene diversity on this species. The aim of this graduate thesis is to determine the level of diversity of the MHC system class II DQA, DQB and DRB genes in golden jackals from Israel. Three alleles at DQA locus, five alleles at DQB locus and four alleles at the DRB locus were found in 30 samples of jackal's ear. Methods used were DNA isolation, PCR method, electrophoresis, sequencing and molecular cloning. We found one new unique allele on DRB locus (DRB1*04802var). The rest of the alleles found are known from previous research on the other species of the dog family, which confirms the existance of a trans-species polymorphism. DQB and DRB loci show great diversity of alleles, large evolutionary distances, high ratio of non-synonymous versus synonymous substitutions, confirming the assumption that loci are influenced by positive selection