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Vol. 62, 2023
(update: 2023.1.11)
Low Diversity of Major Histocompatibility Complex (MHC) Genes in Endangered Malayan Tapir (Tapirus indicus)
Nurul Adilah Ismail1, Christina Seok Yien Yong1, Simon Yung Wa Sin2, and Geetha Annavi1,*
doi:-
1Department
of Biology, Faculty of Science, Universiti Putra Malaysia, 43400 UPM
Serdang, Selangor Darul Ehsan, Malaysia. E-mail:
adilahismail92@gmail.com (Ismail); chrisyong@upm.edu.my (Yong)
2School
of Biological Sciences, The University of Hong Kong, Pok Fu Lam Road,
Hong Kong SAR. *Correspondence: E-mail: geetha@upm.edu.my (Annavi),
Tel: +60397696621.
E-mail: yungwa.sin@gmail.com (Sin)
(Received 10 March 2022 / Accepted 3 January 2023 / Published -- 2023)
Communicated by Jen-Pan Huang
Malayan tapir (Tapirus indicus)
is listed as Endangered in the IUCN Red List due to multiple threats
such as habitat loss and human disturbance that lead to its population
decline. This increases the risk of inbreeding, which could result in
reduction in genome-wide genetic variation and particularly risky if it
affects the gene responsible for immune response i.e.,
MHC gene. Class I and II MHC genes are responsible for encoding MHC
molecules in the cells that recognise pathogenic peptides and present
them to T-Cells on the cell surface for adaptive immune response.
However, at present there is no study related to the MHC gene in
Malayan tapir yet. This study characterises the MHC class I and II
genes from seven individuals, investigates evidence of balancing
selection and their relationships with homologous genes of other
species. We identified at least one class I gene and four class II
genes. Five sequences of alpha1 (α1) and four of alpha2 (α2) domains of
class I alleles, two DRA, two DQA, three DRB and three DQB of class II
alleles were isolated. α1 and α2 domains of class I and DRβ domain of
class II gene display evidence of selection with higher rate of
non-synonymous over synonymous substitutions. Within the DRB gene, 24
codons were found to be under selection where 10 are part of the codons
forming the Antigen Binding Site. Genes sequences show species-specific
monophyletic group formation except for class I and DRB genes with
intersperse relationship in their phylogenetic trees which may indicate
occurrence of trans-species polymorphism of allelic lineage. More
studies using RNA samples are needed to identify the gene’s level of
expression.
Key words: MHC gene, Malayan tapir, Endangered mammals, MHC diversity, peptide-binding region.
Citation:
Ismail NA, Yong CSY, Sin SYW, Annavi G. 2023. Low diversity of major
histocompatibility complex (MHC) genes in endangered Malayan tapir (Tapirus indicus). Zool Stud 62:12.
Supplementary
materials: Fig. S1丨
Fig. S2丨Fig. S3丨Fig. S4丨Fig. S5丨Fig. S6丨Table. S1丨Table S2
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