PDA

View Full Version : A case of "mother's curse" among Quebec's pioneers



Moi-même
28-08-17, 03:07
A paper published in Nature (https://www.nature.com/articles/s41559-017-0276-6.epdf?referrer_access_token=CJC_wnGwDYGI8uEcJ5wGU tRgN0jAjWel9jnR3ZoTv0PRucmNKQoKL9rgBxQEB1KvEUQcRKN zm1KZucpxppXAAbvee7wxSwbElaXrCyvx1kxR63noCFpjpVsr2 06dwp3x3sSk9K9r5_i4_SN9XDtPNKocj7m76HoTYVow5BKdzyn pup4TrX4wVEj6_Fs1bxBaaIVNZkBqzf6Gsf6oZNhcrM9URPs3B elibbGkuDK8sClN6yToH7aNIWqJb90yEd8Bpo6ygJik5IsWvsu aHjCsGxAL-Lo2Y6cLspD2pPCHTywIwwi8brfFAZWh9r_Li2Pd&tracking_referrer=blogues.lapresse.ca) where they study the descendants of one of Quebec settlers, carrier of the mt-mutation T14484C. This one is know to favor Leber Hereditary Optic Neuropathy. Studying the lifes of her mt-descendants through the extensive Quebec genealogy database, it seems the males were 35% less prolific while female were unaffected.


According to evolutionary theory, mitochondria could be poisoned gifts that mothers transmit to their sons. This is because mutations harmful to males are expected to accumulate in the mitochondrial genome, the so-called ‘mother’s curse’. However, the contribution of the mother’s curse to the mutation load in nature remains largely unknown and hard to predict, because compensatory mechanisms could impede the spread of deleterious mitochondria. Here we provide evidence for the mother’s curse in action over 290 years in a human population. We studied a mutation causing Leber’s hereditary optical neuropathy, a disease with male-biased prevalence and which has long been suspected to be maintained in populations by the mother’s curse. Male carriers showed a low fitness relative to non-carriers and to females, mostly explained by their high rate of infant mortality. Despite poor male fitness, selection analysis predicted a slight (albeit non-significant) increase in frequency, which sharply contrasts with the 35.5% per-generation decrease predicted if mitochondrial DNA transmission had been through males instead of females. Our results are therefore even suggestive of positive selection through the female line that may exac-erbate effects of the mother’s curse. This study supports a contribution of the mother’s curse to the reduction of male lifespan, uncovering a large fitness effect associated with a single mitochondrial variant.

Arnaud
29-08-17, 21:37
Very interesting