Submitted to: Animal Genetics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: November 30, 2004
Publication Date: January 1, 2005
Citation: Kim, J.G., Nonneman, D.J., Vallet, J.L., Rohrer, G.A., Christenson, R.K. 2005. (Brief note) Linkage mapping of the porcine myelin basic protein gene to chromosome 1. Animal Genetics. 36(2):163-164. Interpretive Summary: Myelin basic protein (MBP) constitutes 30% of the total myelin protein in the myelin sheaths that cover nerve cells in the central nervous system. MBP is also present in various different White blood cell types. Because fetal red blood cell production influences uterine capacity in pigs and MBP is expressed in red blood cell precursors, we hypothesized that MBP may influence early fetal development. A cDNA clone of the porcine MBP (GenBank no. AY603684) was isolated from the "Meat Animal Research Center (MARC) 2 PIG" cDNA library and sequenced, and the amino acid sequence of the MBP protein was inferred. The putative amino acid sequence of porcine MBP shares 91% identity with human MBP. Next, we explored the MBP gene for differences in the DNA nucleotide sequence (SNPs). The gene was sequenced in the eight parents (seven F1 sows and one White composite boar) of the MARC Swine Reference Population. A SNP was detected and its inheritance could be observed in the piglets from three of seven F1 sows in the MARC Swine Reference Population. Using these inheritance patterns, the MBP gene was determined to be on swine chromosome 1. This is consistent with previous observations indicating that the human MBP gene is located in an area of human chromosome 18 that is similar to the area of swine chromosome 1 containing the MBP gene.
Technical Abstract: Myelin basic protein (MBP) constitutes 30% of the total myelin protein in the central nervous system. In addition, MBP is present in various different cell types including lymphoid cells and all types of myeloid lineage cells (i.e., macrophages, dendritic cells, granulocytes, megakaryocytes, and erythroblasts). Because fetal erythropoiesis influences uterine capacity in pigs and MBP is expressed in the hematopoietic progenitors, we hypothesized that MBP may influence early fetal development. A cDNA clone of the porcine MBP (GenBank no. AY603684) was isolated from the "Meat Animal Research Center (MARC) 2 PIG" expressed sequence tag (EST) library. The putative porcine MBP amino acid sequence shares 91% identity with the human MBP. This clone lacked a region corresponding to human exon 2. Clones lacking exon 2, due to differential splicing, have been identified in both mouse and human. For single nucleotide polymorphism (SNP) detection, primers were designed to amplify a 419 bp product in the 3' untranslated region of the cDNA. This region was evaluated for SNP in the eight parents (seven F1 sows and one White composite boar) of the MARC Swine Reference Population by sequencing PCR products amplified from genomic DNA. Both strands of the amplified genomic DNA of parents from the MARC Swine Reference Population were sequenced and evaluated for polymorphisms. A G/C single nucleotide polymorphism was detected in the 3' UTR of MBP. This polymorphism was heterozygous in three of the seven F1 sows from the MARC Swine Reference Population. An assay was designed to genotype this polymorphism by primer extension with analyte detection on a MALDI-TOF mass spectrometer using a pair of internal primers. The internal forward and reverse primers correspond to bases 1612-1633 and 1768-1788 of the porcine MBP cDNA (GenBank no. AY603684). This marker generated 39 informative meioses in the MARC swine reference population. The MBP gene was mapped using CRI-MAP to chromosome 1 relative position 82.9 cM. The most significant two-point linkage of MBP was with SW80 and SW780 (LOD = 10.84) at 0.0% recombination. The MBP gene is located on human chromosome 18q23, which shares homology with swine chromosome 1.