A porcine bacterial artificial chromosome (BAC) clone, containing the melanocortin 2 receptor gene (MC2R) was isolated. The complete coding sequence of the MC2R gene, contained in 1 exon, was determined. Polymerase chain reactionโsingle stranded conformational polymorphism (PCRโSSCP) was performed on a 241โbp coding fragment. An Alu__I polymorphism, detecting a silent mutation, was found and typed on unrelated animals of five different pig breeds. The Meishan, Piรฉtrain and Large White breeds differ significantly in allele frequencies from the Landrace and Czech Meat Pig breeds. The melanocortin 5 receptor gene (MC5R) was detected by PCR in the same BAC clone, as could be expected from the human and porcine mapping data. PCRโSSCP was performed on a 200โbp coding of MC5R, but no polymorphisms were detected. The BAC clone was mapped to Sscr6q27 by fluorescent in situ hybridization (FISH). A (CA)~n~__ microsatellite (SGU0002), isolated from the BAC, was localized on chromosome 6 by RH mapping near marker SW1473 and by linkage mapping on the MARC reference family at the same position as the marker SW2173 (97โcM). Allele frequencies, heterozygosity and polymorphism information contents (PIC) values were calculated for the five different pig breeds examined.
The transcription of both genes in porcine liver, heart, kidney, fat, brain, pancreas, stomach, bladder, ovaries, lung, spleen, skin, adrenal gland and muscle tissues was examined by reverse transcriptaseโpolymerase chain reaction. Transcription was detected in skin and adrenal gland tissues for MC2R, while a positive signal was detected for MC5R in kidney, fat, pancreas, skin, adrenal gland and spleen tissues.