Birth weight within the normal range is associated with a variety of adult-onset diseases, but the mechanisms behind these associations are poorly understood1. Previous genome-wide association studies identified a variant in the ADCY5 gene associated both with birth weight and type 2 diabetes, and a second variant, near CCNL1, with no obvious link to adult traits2. In an expanded genome-wide association meta-analysis and follow-up study (up to 69,308 individuals of European descent from 43 studies), we have now extended the number of genome-wide significant loci to seven, accounting for a similar proportion of variance to maternal smoking. Five of the loci are known to be associated with other phenotypes: ADCY5 and CDKAL1 with type 2 diabetes; ADRB1 with adult blood pressure; and HMGA2 and LCORL with adult height. Our findings highlight genetic links between fetal growth and postnatal growth and metabolism.
BackgroundReduced growth is common in children with sickle cell anemia, but few data exist on associations with long-term clinical course. Our objective was to determine the prevalence of malnutrition at enrolment into a hospital-based cohort and whether poor nutritional status predicted morbidity and mortality within an urban cohort of Tanzanian sickle cell anemia patients.
Design and MethodsAnthropometry was conducted at enrolment into the sickle cell anemia cohort (n=1,618; ages 0.5-48 years) and in controls who attended screening (siblings, walk-ins and referrals) but who were found not to have sickle cell anemia (n=717; ages 0.5-64 years).
ResultsSickle cell anemia was associated with stunting (OR=1.92, P<0.001, 36.2%) and wasting (OR=1.66, P=0.002, 18.4%). The greatest growth deficits were observed in adolescents and in boys. Independent of age and sex, lower hemoglobin concentration was associated with increased odds of malnutrition in sickle cell patients. Of the 1,041 sickle cell anemia patients with a body mass index z-score at enrolment, 92% were followed up until September 2009 (n=908) or death (n=50). Body mass index and weight-for-age z-score predicted hospitalization (hazard ratio [HZR]=0.90, P=0.04 and HZR=0.88, P=0.02) but height-for-age z-score did not (HZR=0.93, NS). The mortality rate of 2.5 per 100 person-years was not associated with any of the anthropometric measures.
ConclusionsIn this non-birth-cohort of sickle cell anemia with significant associated undernutrition, wasting predicted an increased risk of hospital admission. Targeted nutritional interventions should prioritize treatment and prevention of wasting.Key words: sickle cell anemia, nutrition, growth, anthropometry, Africa, mortality, morbidity.
Citation
Social transmission of information is taxonomically widespread and could have profound effects on the ecological and evolutionary dynamics of animal communities. Demonstrating this in the wild, however, has been challenging. Here we show by field experiment that social transmission among predators can shape how selection acts on prey defences. Using artificial prey and a novel approach in statistical analyses of social networks, we find that blue tit (Cyanistes caeruleus) and great tit (Parus major) predators learn about prey defences by watching others. This shifts population preferences rapidly to match changes in prey profitability, and reduces predation pressure from naïve predators. Our results may help resolve how costly prey defences are maintained despite influxes of naïve juvenile predators, and suggest that accounting for social transmission is essential if we are to understand coevolutionary processes.
Prey animals that possess chemical defences often advertise their unprofitability to predators by a distinctive and conspicuous visual appearance known as aposematism. However, not all chemically defended species are conspicuous, and some are nearly cryptic. Differences in predator community composition and predator behaviour may explain varied levels of prey conspicuousness. We tested this hypothesis by measuring dietary wariness and learning behaviour of day-old chickens, Gallus gallus domesticus, from four strains of laying hens that have been selected for different levels of egg productivity. We used these strains as model predators to test whether predators that vary in the trade-offs associated with foraging behaviour cause differential survival of chemically defended prey with conspicuous signals. We found that strains differed in how they learned about chemically defended prey, which resulted in significant differences in prey survival. The selection pressures imposed by different types of predator could explain whether chemically defended prey evolve varied levels of conspicuousness. Predators' initial wariness of novel prey was not related to learning at the strain or individual level, but predator wariness increased after exposure to chemical defences. Our study provides support for the hypothesis that the evolution of prey defences depends on variation between ecological communities in predator learning behaviour and experience. (C) 2016 Published by Elsevier Ltd on behalf of The Association for the Study of Animal Behaviour
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