Paleogenetical study of pre‐Columbian samples from Pampa Grande (Salta,Argentina)

Ancient DNA recovered from 21 individuals excavated from burial sites in the Pampa Grande (PG) region (Salta province) of North‐Western Argentina (NWA) was analyzed using various genetic markers (mitochondrial DNA, autosomal STRs, and Y chromosomal STRs). The results were compared to ancient and modern DNA from various populations in the Andean and North Argentinean regions, with the aim of establishing their relationships with PG. The mitochondrial haplogroup frequencies described (11% A, 47% B, and 42% D) presented values comparable to those found for the ancient Andean populations from Peru and San Pedro de Atacama. On the other hand, mitochondrial and Y chromosomal haplotypes were specific to PG, as they did not match any other of the South American populations studied. The described genetic diversity indicates homogeneity in the genetic structure of the ancient Andean populations, which was probably facilitated by the intense exchange network in the Andean zone, in particular among Tiwanaku, San Pedro de Atacama, and NWA. The discovery of haplotypes unique to PG could be due to a loss of genetic diversity caused by recent events affecting the autochthonous populations (establishment of the Inca Empire in the region, colonization by the Europeans). Am J Phys Anthropol 2010. © 2009 Wiley‐Liss, Inc.     

Blind killing of both male and female Drosophila embryos by a natural variant of the endosymbiotic bacterium Spiroplasma poulsonii

Spiroplasma poulsonii is a vertically transmitted endosymbiont of Drosophila melanogaster that causes male‐killing, that is the death of infected male embryos during embryogenesis. Here, we report a natural variant of S. poulsonii that is efficiently vertically transmitted yet does not selectively kill males, but kills rather a subset of all embryos regardless of their sex, a phenotype we call ‘blind‐killing’. We show that the natural plasmid of S. poulsonii has an altered structure: Spaid, the gene coding for the male‐killing toxin, is deleted in the blind‐killing strain, confirming its function as a male‐killing factor. Then we further investigate several hypotheses that could explain the sex‐independent toxicity of this new strain on host embryos. As the second non‐male‐killing variant isolated from a male‐killing original population, this new strain raises questions on how male‐killing is maintained or lost in fly populations. As a natural knock‐out of Spaid, which is unachievable yet by genetic engineering approaches, this variant also represents a valuable tool for further investigations on the male‐killing mechanism.     

Factors associated with difference in prevalence of asthma in children from three cities in China: multicentre epidemiological survey

Objective To determine the factors associated with difference in prevalence of asthma in children in different regions of China.Design Multicentre epidemiological survey.Setting Three cities in China.Participants 10 902 schoolchildren aged 10 years.Main outcome measures Asthma and atopic symptoms, atopic sensitisation, and early and current exposure to environmental factors.Results Children from Hong Kong had a significantly higher prevalence of wheeze in the past year than those from Guangzhou and Beijing (odds ratio 1.64, 95% confidence interval 1.35 to 1.99). Factors during the first year of life and currently that were significantly associated with wheeze were cooking with gas (odds ratio 2.04, 1.34 to 3.13), foam pillows (2.58, 1.66 to 3.99), and damp housing (1.89, 1.26 to 2.83). Factors protecting against wheeze were cotton quilts and the consumption of fruit and raw vegetables.Conclusion Environmental factors and diet may explain the differences in prevalence of asthma between children living in different regions of China.     

Morphometric variation in theAlonsoa meridionalis complex (Scrophulariaceae)

Morphological field studies of 27 populations of theA. meridionalis complex were conducted in Ecuador. It is possible to distinguish four different form series by the position of the stamens in relation to the style. This trait was congruent with the overall morphometric variation, shown by the results of a canonical discriminant analysis (CDA). The taxonomy of the species complex is discussed based upon the results of the CDA. The degree of outcrossing varied in different form series, from a comparatively high degree of selfing to predominantly outcrossing, as indicated by the variation within relative to among populations. This is probably due to the varying potentials for self-deposition owing to differences in the degree of herkogamy.