Genomic location and characterisation of nonclassical MHC class I genes in cattle.
ABSTRACT The cattle major histocompatibility complex (MHC) region contains a variable number of classical class I genes encoding polymorphic, ubiquitously expressed molecules with a role in antigen presentation. Class I cDNA sequences have previously been reported that are thought to derive from putative nonclassical class I genes. We have located four nonclassical class I genes within the cattle genome; three are close to the MIC genes, and one is close to the classical class I genes. The genomic position relative to anchor genes is very similar to the arrangement reported in the pig MHC region. We have designed gene-specific oligonucleotide primers with which to investigate the presence of these genes in distinct and well-defined MHC haplotypes and to assess transcription in different cell types. Analysis and comparison of all sequences allows an assessment of allelic variation in each case. Partial characterisation gives an indication of the possible role and likely importance of each of these genes.
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ABSTRACT: Artificial breeding is an important project to protect, recover and reintroduce endangered species. Knowledge of the population’s genetic diversity at functional loci is important for the establishment of effective captive breeding programs. The major histocompatibility complex (MHC) genes are ideal candidate genetic markers to inform planned breeding, due to their high levels of polymorphism and importance in the main immune coding region of the vertebrate genome. In this study, we constructed BAC-based contigs and isolated six functional MHC class I genes from the giant panda (Ailuropoda melanoleuca), which we designated Aime-C, Aime-F, Aime-I, Aime-K, Aime-L and Aime-1906. Analyses of the tissue expression patterns and full-length cDNA sequences of these class I genes revealed that Aime-C, -F, -I and -L could be considered classical class I loci, due to their extensive expression patterns and normal exonic structures. In contrast, Aime-K and -1906 appeared to be nonclassical genes based on their tissue-specific expression patterns and the presence of an abnormal exon 7 in both genes. We established techniques for genotyping exons 2 and 3 of the classical loci using locus-specific single strand conformation polymorphism (SSCP) and sequence analysis. In the Chengdu captive population, we identified one monomorphic locus (Aime-F) and three polymorphic loci with different numbers of alleles (4/4/4 exon 2 alleles at Aime-C/I/L and 6/5/5 exon 3 alleles at Aime-C/I/L). The distributions of the Aime-C, -I and -L alleles among members of different families were in good agreement with the known pedigree relationships, suggesting that the genotyping results are reliable. Therefore, the MHC-I genotyping techniques established in this study may provide a powerful tool for the future design of scientific breeding or release/reintroduction programs.Chinese Science Bulletin 58(18). · 1.37 Impact Factor
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ABSTRACT: The mammalian conceptus undergoes development in the face of a functional immune system. This characteristic of viviparity creates opportunities and perils for the conceptus. In the period up to hatching from the zona pellucida, the conceptus appears immunologically inert with low expression of major histocompatibility complex (MHC) genes and little evidence for alterations in the function of maternal immune cells. The conceptus may benefit from cytokines produced by leucocytes resident in the reproductive tract or by other cells of the reproductive tract. One cytokine in particular, colony-stimulating factor 2, can promote preimplantation development and cause changes in conceptus function that increase the likelihood that the conceptus develops to term. It is not clear whether activation of specific types of immune responses in early pregnancy can enhance the likelihood of pregnancy success. Semen deposition causes inflammation in the reproductive tract, but there is little evidence that this process is beneficial to pregnancy unless the uterus was exposed to a prior inflammatory event. Around the time of placentation, the period of immunological inertness of the conceptus is replaced by a period of immune activation caused by the expression of interferon genes in ruminants and pigs and MHC class I genes in invasive trophoblast of the horse. The large-scale changes in the endometrium that occur as a result are likely to play an important role to ensure continued development of the conceptus. In contrast, other immune responses generated as a result of disease in the reproductive tract or other tissues (mastitis) can lead to death of the conceptus. Because of this hazard, as well as the possibility that cell-mediated immune responses against the conceptus could occur, the immune system is regulated by both the mother and conceptus to reduce immune responsiveness during pregnancy.Reproduction in Domestic Animals 09/2011; 46 Suppl 3:18-30. · 1.39 Impact Factor
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ABSTRACT: Our aim was to analyse the transcription levels of the three non-classical class Ib genes SLA-6, SLA-7 and SLA-8 of the swine major histocompatibility complex in various tissues and conditions and to compare them to the transcription levels of classical class Ia genes. Twenty-five adult tissues from two pig breeds, pig renal PK15 cells infected with the Pseudorabies virus, and peripheral blood mononuclear cells (PBMCs) stimulated by lipopolysaccharide or a mixture of phorbol myristate acetate and ionomycin were included in our study. Relative transcription was quantified by quantitative real-time PCR. On average, in adult tissues and PBMCs and compared to SLA-6, the transcription level of SLA-Ia genes was 100-1000 times higher, the level of SLA-8 was 10-20 times higher, and that of SLA-7 was five times higher. Thus, SLA-8 is the most transcribed SLA-Ib gene, followed by the SLA-7 and SLA-6 genes. The highest transcription levels of SLA-Ib transcripts were found in the lymphoid organs, followed by the lung and the digestive tract. The tissue variability of expression levels was widest for the SLA-6 gene, with a 1:32 ratio between the lowest and highest levels in contrast to a 1:12 ratio for the SLA-7 and SLA-8 genes and a 1:16 ratio for the SLA-Ia genes. During PK-15 infection and PBMC stimulation, SLA-Ia and SLA-8 genes were downregulated, whereas SLA-6 and SLA-7 were upregulated, downregulated or not significantly modified. Our overall results confirm the tissue-wide transcription of the three SLA-Ib genes and suggest that they have complementary roles.Animal Genetics 10/2011; 42(5):510-20. · 2.58 Impact Factor