Quantifying the relative contributions of the X chromosome,autosomes, and mitochondrial genome to local adaptation*

During local adaptation with gene flow, some regions of the genome are inherently more responsive to selection than others. Recent theory predicts that X‐linked genes should disproportionately contribute to local adaptation relative to other genomic regions, yet this prediction remains to be tested. We carried out a multigeneration crossing scheme, using two cline‐end populations of Drosophila melanogaster, to estimate the relative contributions of the X chromosome, autosomes, and mitochondrial genome to divergence in four traits involved in local adaptation (wing size, resistance to heat, desiccation, and starvation stresses). We found that the mitochondrial genome and autosomes contributed significantly to clinal divergence in three of the four traits. In contrast, the X made no significant contribution to divergence in these traits. Given the small size of the mitochondrial genome, our results indicate that it plays a surprisingly large role in clinal adaptation. In contrast, the X, which represents roughly 20% of the Drosophila genome, contributes negligibly—a pattern that conflicts with theoretical predictions. These patterns reinforce recent work implying a central role of mitochondria in climatic adaptation, and suggest that different genomic regions may play fundamentally different roles in processes of divergence with gene flow.     

The effects of 884 MHz GSM wireless communication signals on headache and other symptoms: an experimental provocation study

Findings from prior studies of possible health and physiological effects from mobile phone use have been inconsistent. Exposure periods in provocation studies have been rather short and personal characteristics of the participants poorly defined. We studied the effect of radiofrequency field (RF) on self-reported symptoms and detection of fields after a prolonged exposure time and with a well defined study group including subjects reporting symptoms attributed to mobile phone use. The design was a double blind, cross-over provocation study testing a 3-h long GSM handset exposure versus sham. The study group was 71 subjects age 18-45, including 38 subjects reporting headache or vertigo in relation to mobile phone use (symptom group) and 33 non-symptomatic subjects. Symptoms were scored on a 7-point Likert scale before, after 1(1/2) and 2(3/4) h of exposure. Subjects reported their belief of actual exposure status. The results showed that headache was more commonly reported after RF exposure than sham, mainly due to an increase in the non-symptom group. Neither group could detect RF exposure better than by chance. A belief that the RF exposure had been active was associated with skin symptoms. The higher prevalence of headache in the non-symptom group towards the end of RF exposure justifies further investigation of possible physiological correlates. The current study indicates a need to better characterize study participants in mobile phone exposure studies and differences between symptom and non-symptom groups.     

Severe Obesity Is Associated With Impaired Arterial Smooth Muscle Function in Young Adults

The degree of arterial dilatation induced by exogenous nitrates (nitrate‐mediated dilatation, NMD) has been similar in obese and normal‐weight adults after single high‐dose glyceryl trinitrate (GTN). We examined whether NMD is impaired in obesity by performing a GTN dose‐response study, as this is a potentially more sensitive measure of arterial smooth muscle function. In this cross‐sectional study, subjects were 19 obese (age 31.0 ± 1.2 years, 10 male, BMI 44.1 ± 2.1) and 19 age‐ and sex‐matched normal‐weight (BMI 22.4 ± 0.4) young adults. Blood pressure (BP), triglycerides, high‐density lipoprotein (HDL), and low‐density lipoprotein (LDL)‐cholesterol, glucose, insulin, high‐sensitivity C‐reactive protein (hs‐CRP), carotid intima‐media thickness (CIMT), and flow‐mediated dilatation (FMD) were measured. After incremental doses of GTN, brachial artery maximal percent dilatation (maximal NMD) and the area under the dose‐response curve (NMD AUC) were calculated. Maximal NMD (13.4 ± 0.9% vs. 18.3 ± 1.1%, P = 0.002) and NMD AUC (54,316 ± 362 vs. 55,613 ± 375, P = 0.018) were lower in obese subjects. The obese had significantly higher hs‐CRP, insulin, and CIMT and lower HDL‐cholesterol. Significant bivariate associations existed between maximal NMD or NMD AUC and BMI‐group (r = ?0.492, P = 0.001 or r = ?0.383, P = 0.009), hs‐CRP (r = ?0.419, P = 0.004 or r = ?0.351, P = 0.015), and HDL‐cholesterol (r = 0.374, P = 0.01 or r = 0.270, P = 0.05). On multivariate analysis, higher BMI‐group remained as the only significant determinant of maximal NMD (r² = 0.242, β = ?0.492, P = 0.002) and NMD AUC (r² = 0.147, β = ?0.383, P = 0.023). In conclusion, arterial smooth muscle function is significantly impaired in the obese. This may be important in their increased cardiovascular risk.     

Field dispersal of the parasitoid wasp Habrobracon hebetor (Hymenoptera: Braconidae) following augmentative release against the millet head miner Heliocheilus albipunctella (Lepidoptera: Noctuidae) in the Sahel

Pearl millet is one of the major staple food crops in Sub-Sahelian Africa, and the millet head miner (MHM) [Heliocheilus albipunctella] is its major pest, causing serious economic damage in the maturity period. We studied the dispersion patterns of the endogenous ectoparasitoid, Habrobracon hebetor (Hymenoptera: Braconidae), after augmentative releases in pearl millet fields for biological control of the MHM, in 2010 and 2011 in Burkina Faso and Niger. The parasitoids were released using 15 jute bags per release site. Parasitoid dispersion was indirectly monitored through weekly assessments of MHM parasitism by H. hebetor at different distances from release points (0, 3 and 5?km) and in control villages (15?km). Our findings indicate that the jute bags released approximately 900–1000 parasitoids per site over a period of three weeks. This initial parasitoid population led to higher parasitism of MHM larvae at the site of dissemination compared to farms at distances of 3 and 5?km. However, usually after five weeks, successive generations of H. hebetor dispersed up to 3?km, causing high levels of MHM larval mortality, which sometimes is similar to those of the release points. Based on these results, we recommend the release of parasitoids at sites spaced 3?km for timely and more efficient control of MHM populations.     

Regulatory role of auxin in adventitious root formation in two species of Rumex,differing in their sensitivity to waterlogging

Adventitious rooting in Rumex plants, in which the root systems were in hypoxic conditions, differed considerably between two species. R. palustris, a species from frequently flooded river forelands, developed a large number of adventitious roots during hypoxia, whereas adventitious root formation was poor in R. thyrsiflorus, a species from seldom flooded dykes and river dunes. Adventitious rooting could also be evoked in aerated plants of both species by application of auxin (1-naphthaleneacetic acid or indoleacetic acid) to the leaves. The response to auxin was dose-dependent, but even high auxin doses could not stimulate R. thyrsiflorus to produce as many adventitious roots as R. palustris. Consequently, the difference between the species in the amount of adventitious root formation was probably genetically determined, and not a result of a different response to auxin. A prerequisite for hypoxia-induced adventitious root formation is the basipetal transport of auxin within the shoot, as specific inhibition of this transport by N-1-naphthylphthalamic acid severely decreased the number of roots in hypoxia-treated plants. It is suggested that hypoxia of the root system causes stagnation of auxin transport in the root system. This can lead to an accumulation of auxin at the base of the shoot rosette, resulting in adventitious root formation.     

The 2007–2010 Q fever epidemic in The Netherlands: characteristics of notified acute Q fever patients and the association with dairy goat farming

We describe the Q fever epidemic in the Netherlands with emphasis on the epidemiological characteristics of acute Q fever patients and the association with veterinary factors. Data from 3264 notifications for acute Q fever in the period from 2007 through 2009 were analysed. The patients most affected were men, smokers and persons aged 40–60 years. Pneumonia was the most common clinical presentation (62% in 2007 and 2008). Only 3.2% of the patients were working in the agriculture sector and 0.5% in the meat-processing industry including abattoirs. Dairy goat farms with Coxiella burnetii-induced abortion waves were mainly located in the same area where human cases occurred. Airborne transmission of contaminated dust particles from commercial dairy goat farms in densely populated areas has probably caused this epidemic. In 2010, there was a sharp decline in the number of notified cases following the implementation of control measures on dairy goat and sheep farms such as vaccination, hygiene measures and culling of pregnant animals on infected farms. In combination with a rise in the human population with antibodies against C. burnetii, these have most likely ended the outbreak. Development of chronic Q fever in infected patients remains an important problem for years to come.     

Analysis of limb patterning in BMP-7-deficient mice

Bone morphogenetic proteins `BMPs' are polypeptide signaling molecules, belonging to the TGF-β superfamily. They were originally identified by their ability to induce ectopic bone formation, but their expression patterns in embryos suggest multiple functions. BMP-7-deficient mice show among other mesodermal and skeletal patterning defects, polydactyly in the hindlimbs `Luo G, Hofmann C, Bronckers ALJJ, Sohocki M, Bradley A, Karsenty G `1995': Genes Dev 9:2808-2820; Dudley AT, Lyons KM, Robertson EJ `1995': Genes Dev 9:2795-2807'. Here we report a more detailed analysis of the limb phenotype in BMP-7-deficient mice using in situ hybridization to monitor expression of molecules implicated in patterning processes of the developing vertebrate limb. In previous studies we showed that Sonic hedgehog (Shh) was expressed normally, but Hoxd-13 expression in limb mesenchyme was lower in BMP-7 mutant limbs. Here we show that Hoxd-11 expression domains are also contracted and decreased in intensity in mutant limbs, suggesting that 5′ genes of the Hoxd cluster are coordinately downregulated, while another Bmp, Bmp-2, which can be activated by Shh, is similarly expressed. The mutant limb buds are broader than normal buds, and fibroblast growth factor Fgf-8 is expressed throughout the extended ridge. However, expression of the homeobox gene Msx-1, which has been shown to be involved in epithelial-mesenchymal interactions during limb development, was decreased in the mesenchyme of BMP-7 mutant limbs. Taken together, our data suggest that BMP-7 is involved in regulating proliferation and/or epithelial-mesenchymal interactions in the developing limb. © 1996 Wiley-Liss Inc.