Gènes impliqués dans la conversion des acides gras (de chaines courtes à chaines longues). Du point de vue évolutionnaire, la sélection de tel ou tel gène ou de tel ou tel allèle de ces gènes a probablement été influencé par l’accès plus ou moins direct à des acides gras à chaine longue issus de produits animaux, au gré des périodes glaciaires, puis des évolutions néolithiques.
Oilseeds and fat crops and lipids, 2018
The polymorphismof this gene appears to have been essential in allowing theHomogenus to adapt to its food, and for itsevolution. It provides an undeniable advantage in terms of the productivity of fat synthesis (DHA), and maypartly explain positive selection. With the advent of cooking and new mutations producing even moreFADS2, the brain reached its maximum size inHomo neanderthalensis, in a food ecosystem that providedfavorable quantities ofa-Linolenic acid and DHA. However, the Würm glaciation upset this equilibrium,revealing its fragility as regards to the brain and fertility.Homo sapiens, benefiting from new variants of theFADS2gene, were able to adapt to this harsh environment, whereas Neanderthal man was unable to do soand became extinct.
Here we demonstrate, using ancient and modern DNA, that positive selection acted on the same FADS variants both before and after the advent of farming in Europe, but on opposite (that is, alternative) alleles. Recent selection in farmers also varied geographically, with the strongest signal in southern Europe. These varying selection patterns concur with anthropological evidence of varying diets, and with the association of farming-adaptive alleles with higher FADS1expression and thus enhanced LCPUFA biosynthesis. Genome-wide association studies reveal that farming-adaptive alleles not only increase LCPUFAs, but also affect other lipid levels and protect against several inflammatory diseases
Kumar S. D. Kothapalli et al.
Molecular biology of evolution, 2016
Conversion vers la vitamine A
Single nucleotide polymorphisms upstream from the β-carotene 15,15′-monoxygenase gene influence provitamin A conversion efficiency in female volunteers.
Lietz G1, Oxley A, Leung W, Hesketh J.
β-Carotene, the most abundant provitamin A carotenoid in the diet, is converted to retinal by β-carotene 15,15′-monoxygenase (BCMO1). However, β-carotene absorption and conversion into retinal is extremely variable among individuals, with proportions of low responders to dietary β-carotene as high as 45%. Recently, 2 common nonsynonymous single nucleotide polymorphisms (SNPs) within the BCMO1 coding region (R267S; rs12934922 and A379V; rs7501331) revealed reduced catalytic activity, confirming that genetic variations contribute to the low responder phenotype. Because 4 SNPs 5′ upstream from the BCMO1 gene were recently shown to affect circulating carotenoid concentrations, the current study aimed to investigate the effects of these SNPs on β-carotene conversion efficiency. Three of the 4 polymorphisms (rs6420424, rs11645428, and rs6564851) reduced the catalytic activity of BCMO1 in female volunteers by 59, 51, and 48%, respectively. The TG-rich lipoprotein fraction retinyl palmitate:β-carotene ratio was negatively correlated with the G allele of rs11645428 (r = -0.44; P = 0.018), whereas it was positively correlated with the G allele of rs6420424 (r = 0.53; P = 0.004) and the T allele of rs6564851 (r = 0.41; P = 0.028). Furthermore, large inter-ethnic variations in frequency of affected alleles were detected, with frequencies varying from 43 to 84% (rs6420424), 52 to 100% (rs11645428), and 19 to 67% (rs6564851). In summary, a range of SNPs can influence the effectiveness of using plant-based provitamin A carotenoids to increase vitamin A status in at-risk population groups and this effect may vary depending on ethnic origin.
Natural selection on HFE in Asian populations contributes to enhanced non-heme iron absorption
Kaixiong Ye et al.
BMC genetics, 2015
Meat Consumption During Pregnancy and Substance Misuse Among Adolescent Offspring: Stratification of TCN2 Genetic Variants
Joseph R. Hibbeln et al., 2017
Lower meat consumption disproportionally increased the risks of offspring substance misuse among mothers with optimally functional (homozygous) variants (rs1801198) of the gene transcobalamin 2 gene (TCN2) which encodes the vitamin B12 transport protein transcobalamin 2 implicating a causal role for cobalamin deficits.
[…]Lower prenatal meat consumption was associated with increased risks of adolescent substance misuse. Interactions between TCN2 variant status and meat intake implicate cobalamin deficiencies.
Digestion des produits laitiers
Early Mongolians ate dairy, but lacked the gene to digest it
DNA analysis of the same ancient individuals shows that as adults they lacked the ability to digest lactose, a key sugar in milk. The findings present a puzzle, because they suggest dairying and lactose tolerance may be disconnected. That challenges an oft-told tale of how this adaptation evolved and spread in populations in Europe and Africa. Mongolians’ fondness for fermented milk products—using bacteria to help them digest lactose—may help explain the riddle.
Lactase persistence may explain the paradoxical findings of high vitamin D concentrations in Europeans living in areas of low UV-B irradiation
Sorthe & Moghaddam
European journal of clinical nutrition, 2018
In a recent study of adult-type lactase persistence (LP), it was shown that Caucasian of European descent, who carried the C-13910T LP allele, had higher levels of total serum 25-hydroxyvitamin D compared with those who were lactase non-persistent. This was attributed to higher consumption of dairy. We postulated that the distribution of the LP C-13910T allele in Caucasian populations may explain the vitamin D concentration pattern seen in Europe.