scholarly journals Genetic variation of the major histocompatibilty complex-B haplotypes in Nigerian local chicken populations

2020 ◽  
Vol 53 (4) ◽  
pp. 175-181
Author(s):  
Olanrewaju Teslim Olufowobi ◽  
Babatunde Moses Ilori ◽  
Olajide Olowofeso ◽  
Olajide Mark Sogunle ◽  
Adewunmi Omolade Omotoso
Keyword(s):  
Genetic Diversity ◽  
Major Histocompatibility Complex ◽  
Polymerase Chain Reaction Amplification ◽  
Evolutionary Relationship ◽  
Major Histocompatibility ◽  
Analysis Of Molecular Variance ◽  
Molecular Variance ◽  
Histocompatibility Complex ◽  
Breeding Programmes ◽  
Local Chicken

AbstractTo understand the genetic basis and mechanism underlying the differences in the level of immunity among and within chicken populations in Nigeria, it is important to start from the Major Histocompability Complex (MHC) region particularly as it serves as a reservoir for genes of the immune system. The B-complex of chicken major histocompatibility complex, located on microchromosome 16, consists of gene classes responsible for immunity through antigen presentation to T cells. A highly polymorphic tandem repeat marker (LEI0258) located within the B-complex has been a marker of choice for genotyping to identify major histocompatibility complex-B haplotypes and to study the genetic diversity of chicken populations. This study was carried out to determine the genetic variations, at the LEI0258 locus, in three Nigerian local chicken populations; Normal feather, Frizzle feather and Naked neck. The allelic and genotypic profiles of each representative from each population were determined through polymerase chain reaction amplification of the repeat region. The genetic diversity parameters, analysis of molecular variance and evolutionary relationship were determined using GenAlex, FSTAT, Arlequin and POPTREEW, respectively. 76 % of the entire population was heterozygous at the LEI0258 locus. Analysis of molecular variance revealed that large proportion of the total variations across populations was due to variation between individuals (79 %), whereas variations among the populations and among individuals within populations only accounted for less than 1 % and 21 %, respectively. Using Anak Titan as an exotic outgroup, the evolutionary relationship among the Nigerian local chicken populations was studied and a Nei-based dendrogram showed two major clades separating the exotic population from the Nigerian local chicken populations. The identified diversity at the locus could be exploited for usage in further breeding programmes especially for disease resistance and fitness in locally adapted chicken populations in Nigerian.

Genetic diversity at the Major Histocompatibility Complex class II DZB gene, and geographical distribution of alleles, in platypuses in a Tasmanian river catchment.

2019 ◽  
Vol 40 (2) ◽  
pp. 241-250
Author(s):  
J.W. Macgregor ◽  
C. Holyoake ◽  
S. Munks ◽  
J.H. Connolly ◽  
I.D. Robertson ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Major Histocompatibility Complex ◽  
Mhc Class Ii ◽  
Class Ii ◽  
Major Histocompatibility ◽  
Island Populations ◽  
Low Genetic Diversity ◽  
Histocompatibility Complex ◽  
Wildlife Populations ◽  
River Catchments

Genetic diversity at loci concerned with fitness is an important part of the ability of a wild population to adapt to changes in its environment, including climatic events, disease and pollution. Research into the effects of genetic diversity on the impacts of disease on wildlife populations has focussed on genes of the major histocompatibility complex (MHC). This study investigated the genetic diversity at the MHC class II DZB gene, as well as the distribution of alleles of the same gene, for platypuses Ornithorhynchus anatinus in the Seabrook Creek Catchment in northwest Tasmania. This study detected 10 previously identified alleles and two previously unreported alleles at the MHC Class II DZB locus in 18 platypuses from the Seabrook Creek Catchment. An additional sequence isolated from two individuals was consistent with a pseudogene. Alleles were reasonably well distributed geographically through the catchment, but there was evidence of a degree of isolation at one site. Consistent with evidence that smaller wildlife populations have relatively low genetic diversity, and that there is relatively slow gene flow between river catchments, the observed genetic diversity at the MHC Class II locus was lower than those in larger previously studied river catchments but higher than those in two island populations. Consequently, this population of platypuses may have a limited capacity to respond to new infectious challenges, such as the fungal disease mucormycosis.

scholarly journals Polymorphism in the major histocompatibility complex (MHC class II B) genes of the Rufous-backed Bunting (Emberiza jankowskii)

PeerJ ◽  
2017 ◽  
Vol 5 ◽  
pp. e2917 ◽  
Author(s):  
Dan Li ◽  
Keping Sun ◽  
Yunjiao Zhao ◽  
Aiqing Lin ◽  
Shi Li ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Major Histocompatibility Complex ◽  
Mhc Class Ii ◽  
Nucleotide Diversity ◽  
Environmental Changes ◽  
Major Histocompatibility ◽  
High Genetic Diversity ◽  
Exon 2 ◽  
Histocompatibility Complex ◽  
Segregating Sites

Genetic diversity is one of the pillars of conservation biology research. High genetic diversity and abundant genetic variation in an organism may be suggestive of capacity to adapt to various environmental changes. The major histocompatibility complex (MHC) is known to be highly polymorphic and plays an important role in immune function. It is also considered an ideal model system to investigate genetic diversity in wildlife populations. The Rufous-backed Bunting (Emberiza jankowskii) is an endangered species that has experienced a sharp decline in both population and habitat size. Many historically significant populations are no longer present in previously populated regions, with only three breeding populations present in Inner Mongolia (i.e., the Aolunhua, Gahaitu and Lubei557 populations). Efforts focused on facilitating the conservation of the Rufous-backed Bunting (Emberiza jankowskii) are becoming increasingly important. However, the genetic diversity ofE. jankowskiihas not been investigated. In the present study, polymorphism in exon 2 of the MHCIIB ofE. jankowskiiwas investigated. This polymorphism was subsequently compared with a related species, the Meadow Bunting (Emberiza cioides). A total of 1.59 alleles/individual were detected inE. jankowskiiand 1.73 alleles/individual were identified inE.cioides. The maximum number of alleles per individual from the threeE. jankowskiipopulations suggest the existence of at least three functional loci, while the maximum number of alleles per individual from the threeE. cioidespopulations suggest the presence of at least four functional loci. Two of the alleles were shared between theE. jankowskiiandE. cioides. Among the 12 unique alleles identified inE. jankowskii, 10.17 segregating sites per allele were detected, and the nucleotide diversity was 0.1865. Among the 17 unique alleles identified inE. cioides, eight segregating sites per allele were detected, and the nucleotide diversity was 0.1667. Overall, compared to other passerine birds, a relatively low level of MHC polymorphism was revealed inE. jankowskii, which was similar to that inE. cioides. Positive selection was detected by PAML/SLAC/FEL analyses in the region encoding the peptide-binding region in both species, and no recombination was detected. Phylogenetic analysis showed that the alleles fromE. jankowskiiandE. cioidesbelong to the same clade and the two species shared similar alleles, suggesting the occurrence of a trans-species polymorphism between the twoEmberizaspecies.

scholarly journals Genetic diversity, evolution and selection in the major histocompatibility complex DRB and DQB loci in the family Equidae

BMC Genomics ◽  
2020 ◽  
Vol 21 (1) ◽  
Author(s):  
Marie Klumplerova ◽  
Petra Splichalova ◽  
Jan Oppelt ◽  
Jan Futas ◽  
Aneta Kohutova ◽  
...  
Keyword(s):  
Genetic Diversity ◽  
Major Histocompatibility Complex ◽  
Positive Selection ◽  
Mhc Class Ii ◽  
Class Ii ◽  
Major Histocompatibility ◽  
Histocompatibility Complex ◽  
Depth Analysis ◽  
The Family ◽  
Antigen Presenting

Abstract Background The mammalian Major Histocompatibility Complex (MHC) is a genetic region containing highly polymorphic genes with immunological functions. MHC class I and class II genes encode antigen-presenting molecules expressed on the cell surface. The MHC class II sub-region contains genes expressed in antigen presenting cells. The antigen binding site is encoded by the second exon of genes encoding antigen presenting molecules. The exon 2 sequences of these MHC genes have evolved under the selective pressure of pathogens. Interspecific differences can be observed in the class II sub-region. The family Equidae includes a variety of domesticated, and free-ranging species inhabiting a range of habitats exposed to different pathogens and represents a model for studying this important part of the immunogenome. While equine MHC class II DRA and DQA loci have received attention, the genetic diversity and effects of selection on DRB and DQB loci have been largely overlooked. This study aimed to provide the first in-depth analysis of the MHC class II DRB and DQB loci in the Equidae family. Results Three DRB and two DQB genes were identified in the genomes of all equids. The genes DRB2, DRB3 and DQB3 showed high sequence conservation, while polymorphisms were more frequent at DRB1 and DQB1 across all species analyzed. DQB2 was not found in the genome of the Asiatic asses Equus hemionus kulan and E. h. onager. The bioinformatic analysis of non-zero-coverage-bases of DRB and DQB genes in 14 equine individual genomes revealed differences among individual genes. Evidence for recombination was found for DRB1, DRB2, DQB1 and DQB2 genes. Trans-species allele sharing was identified in all genes except DRB1. Site-specific selection analysis predicted genes evolving under positive selection both at DRB and DQB loci. No selected amino acid sites were identified in DQB3. Conclusions The organization of the MHC class II sub-region of equids is similar across all species of the family. Genomic sequences, along with phylogenetic trees suggesting effects of selection as well as trans-species polymorphism support the contention that pathogen-driven positive selection has shaped the MHC class II DRB/DQB sub-regions in the Equidae.

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