Molecular cloning and characterization of the polymorphic MHC class�II DBB from the tammar wallaby (Macropus eugenii)

Browning, Teena L.; Belov, Katherine; Miller, Robert D.; Eldridge, Mark D. B.

doi:10.1007/s00251-004-0644-7

Cited by 20 publications

(8 citation statements)

References 25 publications

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“…Indeed, studies of the marsupial MHC have lagged behind those of their eutherian counterparts due to the large differences in the structure and organisation of this gene region between the two orders Schneider et al 1991). Only recently have attempts been made to fully characterise the marsupial MHC (Belov et al 2006;Browning et al 2004;Miska and Miller 1999). This has meant that population genetic researchers wanting to incorporate information from the MHC have had to wait for adequate data on conserved gene sequences to become available.…”

Section: Introductionmentioning

confidence: 99%

MHC screening for marsupial conservation: extremely low levels of class II diversity indicate population vulnerability for an endangered Australian marsupial

2009

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Variation at genetic regions of functional significance is a new focus in conservation genetics. One of the prime candidates for such studies is the major histocompatibility complex (MHC). This gene region, with its critical role in immune response in vertebrates, is thought to have a significant impact on population fitness. The screening of diversity at MHC regions in non-model organisms presents a number of challenges that need to be overcome before its widespread incorporation into conservation programs. Here we present an approach and data for the screening of diversity at a class II MHC locus in wild and captive populations of the western barred bandicoot (Perameles bougainville). Primers developed to amplify the DAB gene in the tammar wallaby were modified to amplify the same gene in western barred bandicoots. Alleles were identified by cloning and sequencing of PCR products. Screening of all populations was carried out via high resolution melt analysis (HRM) and revealed just two sequence copies for this gene present in every individual from all populations. Alignment of translated amino acid sequences show that these variants contain many conserved elements indicative of functional MHC class II genes and suggest that they represent separate duplicated loci. Such a low level of MHC diversity is surprising for wild mammalian populations and exposes this species to increased vulnerability to novel disease pathogens.

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Section: Introductionmentioning

confidence: 99%

MHC screening for marsupial conservation: extremely low levels of class II diversity indicate population vulnerability for an endangered Australian marsupial

2009

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“…Past efforts to identify structural components of the metatherian immune system resulted in the detection of various genes and processes (e.g., major histocompatibility complex [MHC] genes, T-cell receptors, immunoglobulins, generation of antigenreceptor diversity via somatic V-D-J recombination) that sufficiently resembled those of humans and mice to suggest that the metatherian immunologic toolkit was generally similar to that of eutherian species (in the absence of comprehensive reviews, see Stone et al 1996Stone et al , 1998Miller and Belov 2000;Belov et al 2002aBelov et al ,b, 2004Belov et al , 2006Browning et al 2004;Miska et al 2004;Baker et al 2005;Gouin et al 2006b;Samollow 2006). Nevertheless, the vast evolutionary distance between the metatherian and eutherian clades made it difficult to identify metatherian homologs of genes within the more rapidly evolving components of the immune system, so the overall complexity and diversity of gene families in major arms of the immune system remained largely unknown.…”

Section: Immunogeneticsmentioning

confidence: 99%

The opossum genome: Insights and opportunities from an alternative mammal

Samollow¹

2008

Genome Res.

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The strategic importance of the genome sequence of the gray, short-tailed opossum, Monodelphis domestica, accrues from both the unique phylogenetic position of metatherian (marsupial) mammals and the fundamental biologic characteristics of metatherians that distinguish them from other mammalian species. Metatherian and eutherian (placental) mammals are more closely related to one another than to other vertebrate groups, and owing to this close relationship they share fundamentally similar genetic structures and molecular processes. However, during their long evolutionary separation these alternative mammals have developed distinctive anatomical, physiologic, and genetic features that hold tremendous potential for examining relationships between the molecular structures of mammalian genomes and the functional attributes of their components. Comparative analyses using the opossum genome have already provided a wealth of new evidence regarding the importance of noncoding elements in the evolution of mammalian genomes, the role of transposable elements in driving genomic innovation, and the relationships between recombination rate, nucleotide composition, and the genomic distributions of repetitive elements. The genome sequence is also beginning to enlarge our understanding of the evolution and function of the vertebrate immune system, and it provides an alternative model for investigating mechanisms of genomic imprinting. Equally important, availability of the genome sequence is fostering the development of new research tools for physical and functional genomic analyses of M. domestica that are expanding its versatility as an experimental system for a broad range of research applications in basic biology and biomedically oriented research.Compilation and publication of the genome sequence of the gray short-tailed opossum, Monodelphis domestica, a metatherian (marsupial) mammal (Mikkelsen et al. 2007b), create unique opportunities for investigating the evolutionary processes that have shaped the structural and functional attributes of mammalian and other vertebrate genomes. These opportunities arise from both the unique phylogenetic position of metatherians in the vertebrate scheme and some fundamental characteristics of metatherians that distinguish them from other mammalian species.Modern mammals comprise three major lineages (Fig. 1). Judged from multiple nuclear sequence and mtDNA alignments, the most closely related of these, the Metatheria and Eutheria (placental mammals), diverged from their most recent common ancestor ∼173-190 million years ago (Mya) (Kumar and Hedges 1998;Woodburne et al. 2003;van Rheede et al. 2006). The other major clade, the Prototheria, of which the egg-laying monotremes (platypus and four species of echidnas) are the only living representatives, branched off 20-35 million years (Myr) prior to the metatherian-eutherian divergence (Phillips and Penny 2003;Woodburne et al. 2003;van Rheede et al. 2006). 2 By way of reference, the separation of mammals and birds occurred at least 310 Mya (d...

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“…It is anticipated that such a comparison would highlight variable regions within the MHC of marsupials. Knowledge of the wallaby MHC is predominantly limited to cDNA sequences for a class II ␣ and ␤ chain (Slade et al, 1994;Browning et al, 2004) and six class I cDNA sequences out of a total of at least 11 class I loci (Siddle et al, 2006). Class III cDNAs for LTA , TNF and LTB have also been reported Deane, 1999, 2000) and the genomic region surrounding these three loci has been characterized (Cross et al, 2005).…”

Section: Abstract Genes Within the Major Histocompatibilitymentioning

confidence: 99%

“…DBA primers were designed to amplify a 180-base pair region of a mammalian class II alpha chain ( ␣ 2 domain, exon 3) by aligning class II alpha chain sequences from human: HLA-DQA , M33906; pig: SLA-DQA , DQ003300; cow: BoLA-DRA , D37956; BoLA-DQA , AY730727; sheep: Ovar-DRA , M73983, Ovar-DQA2 , M93431; dog: DLA-DRA , L37332; rabbit: RLA-DRA , M28161; and red-necked wallaby: Maru-DNA , U18110; Maru-DRA , U18109. DBB primers were as previously described by Browning et al (2004) and DAB primers were kindly supplied by Teena Browning (Macquarie University, Australia). TAP1 primers were designed by aligning seven cDNA sequences from six species ( Gorilla gorilla, L76468; Mus musculus, U60018; Mesocricetus aureatus , AF001156; Homo sapiens TAP1A , L21204; Homo sapiens TAP1B , L21205; Oryctolagus cuniculus , AJ297383; Rattus norvegicus , Y10230).…”

Section: Pcr and Overgo Primer Designmentioning

confidence: 99%

Class I genes have split from the MHC in the tammar wallaby

Deakin

Siddle²,

Cross³

et al. 2007

Cytogenet Genome Res

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Genes within the Major Histocompatibility Complex (MHC) are critical to the immune response and immunoregulation. Comparative studies have revealed that the MHC has undergone many changes throughout evolution yet in tetrapods the three different classes of MHC genes have maintained linkage, suggesting that there may be some functional advantage obtained by maintaining this clustering of MHC genes. Here we present data showing that class II and III genes, the antigen processing gene TAP2, and MHC framework genes are found together in the tammar wallaby on chromosome 2. Surprisingly class I loci were not found on chromosome 2 but were mapped to ten different locations spread across six chromosomes. This distribution of class I loci in the wallaby on nearly all autosomes is not a characteristic of all marsupials and may be a relatively recent phenomenon. It highlights the need for the inclusion of more than one marsupial species in comparative studies and raises questions regarding the functional significance of the clustering of MHC genes.

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Molecular cloning and characterization of the polymorphic MHC class�II DBB from the tammar wallaby (Macropus eugenii)

Cited by 20 publications

References 25 publications

MHC screening for marsupial conservation: extremely low levels of class II diversity indicate population vulnerability for an endangered Australian marsupial

MHC screening for marsupial conservation: extremely low levels of class II diversity indicate population vulnerability for an endangered Australian marsupial

The opossum genome: Insights and opportunities from an alternative mammal

Class I genes have split from the MHC in the tammar wallaby

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