Research press release


Scientific Reports

Genetics: The genes that may seal a pup's fate

ハイイロアザラシの仔の生存率に対する主要組織適合遺伝子複合体(MHC)の影響を調べた研究の結果を報告する論文が、Scientific Reportsに掲載される。この研究では、成体になるまでに死んだハイイロアザラシの最大70%が、MHC遺伝子型を原因としている可能性が示され、特に仔の生存率と強く関連する1個のアレルが同定された。

今回、W Amosたちは、ハイイロアザラシ(Halichoerus grypus)の死亡率とMHC遺伝子型との関係を調べた。その結果、ハイイロアザラシの仔に見られるMHCアレルの数と生殖年齢まで生存する確率との間に強い相関のあることがわかった。つまり、4つのアレルがあれば、成体になるまで生存する確率がほぼ100%で、1つしかない場合には、その確率がかなり低かった。特に、アレル5は、ハイイロアザラシの仔が離乳までに死ぬかどうかを予測する有力な因子として関与していた。このように1つの免疫関連遺伝子を原因とする死亡の割合がこれほど高い事例は稀だとAmosたちは指摘する。


The effect of a cluster of genes known as the major histocompatibility complex (MHC) on the survival rates of grey seal pups is examined in a Scientific Reports paper. The study indicates that as much as 70% of grey seal pup mortality may be attributable to MHC genotype, with one allele in particular being strongly associated with pup survival.

William Amos and colleagues studied the relationship between MHC genotype and mortality in the grey seal (Halichoerus grypus). They found a strong correlation between the number of MHC alleles a seal pup exhibits and its chances of surviving to reproduce: pups with four alleles are almost certain to reach adulthood, whereas those with only one are very unlikely to survive. One particular allele - allele 5 - was implicated as a strong predictor of whether a pup will die before weaning. It is unusual to find such a high proportion of mortality attributable to one immune-related gene, the authors note.

The MHC is a key genetic component of the vertebrate immune system and is thought to inform mate choice in some species by providing olfactory cues. These results suggest why it may be beneficial for female grey seals to mate with MHC-dissimilar males that will father pups that are more likely to survive to adulthood, given their increased MHC heterozygosity and greater chance of carrying allele 5. The authors do caution, however, that the analysis is quite preliminary - they didn't measure the age of the adult seals or the season quality, for example - and that further research could help to shed light on the mechanisms underlying these processes.

doi: 10.1038/srep00659


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