Dynamics of Mhc evolution in birds and crocodilians: amplification of class II genes with degenerate primers.
Genes of the major histocompatibility complex (Mhc) are the most polymorphic functional loci in mammalian populations, but little is known of Mhc variability in natural populations of nonmammalian vertebrates. To help extend such studies to birds and relatives, we present a pair of degenerate primers that amplify polymorphic segments of one chain (the beta chain) of the class II genes from the major histocompatibility complex (Mhc) of archosaurs (birds+crocodilians). The primers target two conserved regions lying within portions of the antigen-binding site (ABS) encoded by the second exon and amplify multiple genes from both genomic DNA and cDNA. The pattern of nucleotide substitution in ABS codons of 51 sequences amplified and cloned from five species of passerine birds and an alligator (Alligator mississippiensis) indicates that archosaurian class II beta genes are subject to selective forces similar to those operating in mammalian populations. Hybridization of a genomic clone generated by the primers revealed highly polymorphic bands in a sample of Florida scrub jays (Aphelocoma coerulescens coerulescens). Because the primers amplify only part of the ABS from multiple class II genes, they will be useful primarily for generating species specific clones, thereby providing a critical inroad to more detailed structural and evolutionary studies.
Edwards
S V
SV
Center for Mammalian Genetics, University of Florida, Gainesville 32610, USA.
Grahn
M
M
Potts
W K
WK
D000489:Alligators and Crocodiles / Q000235:genetics* / Q000276:immunology*; D000818:Animals; D001483:Base Sequence; D005075:Biological Evolution; D001717:Birds / Q000235:genetics* / Q000276:immunology*; D003001:Cloning, Molecular; D017124:Conserved Sequence; D017931:DNA Primers / Q000235:genetics; D017753:Ecosystem; D005784:Gene Amplification; D005802:Genes, MHC Class II; D014644:Genetic Variation; D008285:Major Histocompatibility Complex; D008969:Molecular Sequence Data; D016133:Polymerase Chain Reaction; D012689:Sequence Homology, Nucleic Acid
D017931:DNA Primers