Tracing the Distribution of European Lactase Persistence Genotypes Along the Americas

In adulthood, the ability to digest lactose, the main sugar present in milk of mammals, is a phenotype (lactase persistence) observed in historically herder populations, mainly Northern Europeans, Eastern Africans, and Middle Eastern nomads. As the –13910∗T allele in the MCM6 gene is the most well-characterized allele responsible for the lactase persistence phenotype, the –13910C > T (rs4988235) polymorphism is commonly evaluated in lactase persistence studies. Lactase non-persistent adults may develop symptoms of lactose intolerance when consuming dairy products. In the Americas, there is no evidence of the consumption of these products until the arrival of Europeans. However, several American countries’ dietary guidelines recommend consuming dairy for adequate human nutrition and health promotion. Considering the extensive use of dairy and the complex ancestry of Pan-American admixed populations, we studied the distribution of –13910C > T lactase persistence genotypes and its flanking haplotypes of European origin in 7,428 individuals from several Pan-American admixed populations. We found that the –13910∗T allele frequency in Pan-American admixed populations is directly correlated with allele frequency of the European sources. Moreover, we did not observe any overrepresentation of European haplotypes in the –13910C > T flanking region, suggesting no selective pressure after admixture in the Americas. Finally, considering the dominant effect of the –13910∗T allele, our results indicate that Pan-American admixed populations are likely to have higher frequency of lactose intolerance, suggesting that general dietary guidelines deserve further evaluation across the continent

Ecology of exposed sandy beaches in northern Spain: environmental factors controlling macrofauna communities

Thirty-four exposed sandy beaches on the northern coast of Spain (from 42°11′ to 43°44′N, and from 2°04′ to 8°52′ W; ca. 1000 km) were sampled over a range of beach sizes, beach morphodynamics and exposure rates. Ten equally spaced intertidal shore levels along six replicated transects were sampled at each beach. Sediment and macrofauna samples were collected using corers to a depth of 15 cm. Morphodynamic characteristics such as the beach face slope, wave environment, exposure rates, Dean's parameter and Beach State Index were estimated. Biotic results indicated that in all the beaches the community was dominated by isopods, amphipods and polychaetes, mostly belonging to the detritivorous-opportunistic trophic group. The number of intertidal species ranged from 9 to 31, their density being between 31 and 618 individuals m-2, while individuals per linear metre (m-1) ranged from 4962 to 17 2215. The biomass, calculated as total ash-free dry weight (AFDW) varied from 0.027 to 2.412 g m-2, and from 3.6 to 266.6 g m-1. Multiple regression analysis indicated that number of species significantly increased with proximity to the wind-driven upwelling zone located to the west, i.e., west-coast beaches hosted more species than east-coast beaches. The number of species increased with decreasing mean grain size and increasing beach length. The density of individuals m-2 increased with decreasing mean grain size, while biomass m-2 increased with increasing food availability estimated as chlorophyll-a concentration in the water column of the swash zone. Multiple-regression analysis indicated that chlorophyll-a in the water column increased with increasing western longitude. Additional insights provided by single-regression analysis showed a positive relationship between the number of species and chlorophyll-a, while increasing biomass occurred with increasing mean grain size of the beach. The results indicate that community characteristics in the exposed sandy beaches studied are affected by physical characteristics such as sediment size and beach length, but also by other factors dependent on coastal processes, such as food availability in the water column

Analysis of Lrrk2 R1628P as a risk factor for Parkinson's disease

10.1002/ana.21405Annals of Neurology64188-92ANNE

Planar refraction and lensing of highly confined polaritons in anisotropic media

Refraction between isotropic media is characterized by light bending towards the normal to the boundary when passing from a low- to a high-refractive-index medium. However, refraction between anisotropic media is a more exotic phenomenon which remains barely investigated, particularly at the nanoscale. Here, we visualize and comprehensively study the general case of refraction of electromagnetic waves between two strongly anisotropic (hyperbolic) media, and we do it with the use of nanoscale-confined polaritons in a natural medium: α-MoO(3). The refracted polaritons exhibit non-intuitive directions of propagation as they traverse planar nanoprisms, enabling to unveil an exotic optical effect: bending-free refraction. Furthermore, we develop an in-plane refractive hyperlens, yielding foci as small as λ(p)/6, being λ(p) the polariton wavelength (λ(0)/50 compared to the wavelength of free-space light). Our results set the grounds for planar nano-optics in strongly anisotropic media, with potential for effective control of the flow of energy at the nanoscale

Multicenter analysis of glucocerebrosidase mutations in Parkinson's disease

10.1056/NEJMoa0901281New England Journal of Medicine361171651-1661NEJM