The short‐ and long‐term fitness consequences of natal dispersal in a wild bird population

Dispersal is a key process in population and evolutionary ecology. Individual decisions are affected by fitness consequences of dispersal, but these are difficult to measure in wild populations. A long‐term dataset on a geographically closed bird population, the Mauritius kestrel, offers a rare opportunity to explore fitness consequences. Females dispersed further when the availability of local breeding sites was limited, whereas male dispersal correlated with phenotypic traits. Female but not male fitness was lower when they dispersed longer distances compared to settling close to home. These results suggest a cost of dispersal in females. We found evidence of both short‐ and long‐term fitness consequences of natal dispersal in females, including reduced fecundity in early life and more rapid aging in later life. Taken together, our results indicate that dispersal in early life might shape life history strategies in wild populations.     

A combination of untargeted and targeted metabolomics approaches unveils changes in the kynurenine pathway following cardiopulmonary resuscitation

The mechanisms responsible for post-resuscitation myocardial and cerebral dysfunction are not well understood, especially in the early post-resuscitation phases. In this investigation, we first adopted unbiased mass spectrometry-based metabolomic profiling to identify perturbations in circulating metabolites in a rat model of cardiac arrest and cardiopulmonary resuscitation. Our findings strongly indicated early alterations in a major route of the tryptophan catabolism, namely the kynurenines pathway, after resuscitation. Specific metabolites involved in the tryptophan catabolism were quantified absolutely using liquid chromatography-multiple reaction monitoring-mass spectrometry. Tryptophan plasma concentration fell significantly very early in the post-resuscitation phase, while its metabolites, l-kynurenine, kynurenic acid, 3-hydroxyanthranilic acid and 5-hydroxyindoleacetic acid, rose significantly. Changes in their concentration reflected changes in rat post-resuscitation myocardial dysfunction. Elevated plasma level of kynurenic acid, 3-hydroxyanthranilic acid were associated with significant decrease in ejection fraction and stroke volume. It is well known that kynurenines pathway is involved in the pathogenesis of numerous central nervous system disorders. By implication, altered levels of tryptophan metabolites in the early post resuscitation phase might contribute to the degree of cognitive recovery. Our results suggest that kynurenine pathway is activated early following resuscitation from cardiac arrest and might account for the severity of post-resuscitation syndrome. Our explorative investigation indicate that metabolomics can help to clarify unexplored biochemical pathways in cardiopulmonary resuscitation.     

Resolution Doubling in 3D-STORM Imaging through Improved Buffers

Super-resolution imaging methods have revolutionized fluorescence microscopy by revealing the nanoscale organization of labeled proteins. In particular, single-molecule methods such as Stochastic Optical Reconstruction Microscopy (STORM) provide resolutions down to a few tens of nanometers by exploiting the cycling of dyes between fluorescent and non-fluorescent states to obtain a sparse population of emitters and precisely localizing them individually. This cycling of dyes is commonly induced by adding different chemicals, which are combined to create a STORM buffer. Despite their importance, the composition of these buffers has scarcely evolved since they were first introduced, fundamentally limiting what can be resolved with STORM. By identifying a new chemical suitable for STORM and optimizing the buffer composition for Alexa-647, we significantly increased the number of photons emitted per cycle by each dye, providing a simple means to enhance the resolution of STORM independently of the optical setup used. Using this buffer to perform 3D-STORM on biological samples, we obtained images with better than 10 nanometer lateral and 30 nanometer axial resolution.     

Influence of MDR1 C1236T polymorphism on lopinavir plasma concentration and virological response in HIV-1-infected children

Background

Variability in MDR1 and PXR has been associated with differences in drug plasma levels and response to antiretroviral therapy. We investigated whether polymorphisms in MDR1 (T-129C, C1236T and C3435T) and PXR (C63396T) affect lopinavir plasma concentration and the virological or immunological response to HAART in HIV-1-infected children.

Methods

Genotypes were identified in 100 blood donors and 38 HIV-1-infected children. All children received HAART with lopinavir boosted with ritonavir (LPV/r) at the time of LPV plasma level quantification, before (C_trough) and between 1 and 2 h after (C_post-dose) the administration of the next dose of drug. CD4⁺ T-cell counts and plasma viral load were analyzed before and after the initiation of LPV/r.

Results

MDR1 1236T, MDR1 3435T and PXR 63396T alleles showed a frequency of ~ 50% while the MDR1 -129C allele only reached 5%. Children heterozygotes 1236CT showed a significantly lower LPV C_post-dose than homozygotes 1236TT (median C_post-dose = 3.04 μg/ml and 6.50 μg/ml, respectively; p = 0.016). Children heterozygotes 1236CT also had a lower decrease of viral load after 36 weeks of LPV/r exposure compared with homozygotes 1236CC (median viral load changes = − 0.50 log₁₀ copies/ml and − 2.08 log₁₀ copies/ml, respectively; p = 0.047). No effect on the immunological response was observed for polymorphisms of MDR1 or PXR.

Conclusions

Our results suggest that the MDR1 C1236T SNP significantly reduces LPV plasma concentration affecting the virological response to HAART. Heterozygotes 1236CT might have an altered level of P-gp expression/activity in enterocytes and CD4⁺ T lymphocytes that limits the absorption of LPV leading to an impaired virological suppression.     

Effect of metabolic syndrome risk factors and MMP-2 genetic variations on circulating MMP-2 levels in childhood obesity

Matrix metalloproteinase-2 is involved in the development of the adipose tissue, and associated with cardiovascular diseases. Metabolic risk factors (MRFs) and functional polymorphisms in the MMP-2 gene may affect its expression and activity. We investigated whether traditional MRFs and two MMP-2 gene polymorphisms (C^?1306T; rs243865, and C^?735T; rs2285053) affect circulating MMP-2 levels in children and adolescents, and whether MMP-2 polymorphisms and/or haplotype are associated with susceptibility to childhood obesity. We studied 114 healthy controls, 43 obese, and 83 obese with ≥3 MRFs children and adolescents. Genotypes were determined by Taqman allele discrimination assay and real-time PCR. Plasma MMP-2 was measured using zymography. We found positive correlations between MMP-2 concentrations and mean blood pressure in all children and adolescents group (r = 0.132; P < 0.05) and in obese children and adolescents (r = 0.247; P < 0.01). We found that the CC genotype for the C^?1306T polymorphism was more common in subjects with higher MMP-2 concentrations in controls (P = 0.003) and in the obese group (P = 0.013). The CT genotype (OR = 0.40; P < 0.01) and the T allele (OR = 0.48; P < 0.01) for the C^?735T polymorphism were less common in obese children and adolescents than in controls. The haplotypes distribution did not show significant differences between control and obese (P > 0.05). Ours findings show that blood pressure is associated with circulating MMP-2 concentrations, and that the CC genotype for the C^?1306T polymorphism was more common subjects (controls and obese) with higher MMP-2 concentrations, whereas the CT genotype and the T allele for the C^?735T polymorphism are less common in obesity.     

The Involvement of Mitochondrial Amidoxime Reducing Components 1 and 2 and Mitochondrial Cytochrome b5 in N-Reductive Metabolism in Human Cells

The mitochondrial amidoxime reducing component mARC is a recently discovered molybdenum enzyme in mammals. mARC is not active as a standalone protein, but together with the electron transport proteins NADH-cytochrome b₅ reductase (CYB5R) and cytochrome b₅ (CYB5), it catalyzes the reduction of N-hydroxylated compounds such as amidoximes. The mARC-containing enzyme system is therefore considered to be responsible for the activation of amidoxime prodrugs. All hitherto analyzed mammalian genomes code for two mARC genes (also referred to as MOSC1 and MOSC2), which share high sequence similarities. By RNAi experiments in two different human cell lines, we demonstrate for the first time that both mARC proteins are capable of reducing N-hydroxylated substrates in cell metabolism. The extent of involvement is highly dependent on the expression level of the particular mARC protein. Furthermore, the mitochondrial isoform of CYB5 (CYB5B) is clearly identified as an essential component of the mARC-containing N-reductase system in human cells. The participation of the microsomal isoform (CYB5A) in N-reduction could be excluded by siRNA-mediated down-regulation in HEK-293 cells and knock-out in mice. Using heme-free apo-CYB5, the contribution of mitochondrial CYB5 to N-reductive catalysis was proven to strictly depend on heme. Finally, we created recombinant CYB5B variants corresponding to four nonsynonymous single nucleotide polymorphisms (SNPs). Investigated mutations of the heme protein seemed to have no significant impact on N-reductive activity of the reconstituted enzyme system.     

Scribble is required for normal epithelial cell–cell contacts and lumen morphogenesis in the mammalian lung

During lung development, proper epithelial cell arrangements are critical for the formation of an arborized network of tubes. Each tube requires a lumen, the diameter of which must be tightly regulated to enable optimal lung function. Lung branching and lumen morphogenesis require close epithelial cell–cell contacts that are maintained as a result of adherens junctions, tight junctions and by intact apical–basal (A/B) polarity. However, the molecular mechanisms that maintain epithelial cohesion and lumen diameter in the mammalian lung are unknown. Here we show that Scribble, a protein implicated in planar cell polarity (PCP) signalling, is necessary for normal lung morphogenesis. Lungs of the Scrib mouse mutant Circletail (Crc) are abnormally shaped with fewer airways, and these airways often lack a visible, ‘open’ lumen. Mechanistically we show that Scrib genetically interacts with the core PCP gene Vangl2 in the developing lung and that the distribution of PCP pathway proteins and Rho mediated cytoskeletal modification is perturbed in Scrib^Crc/Crc lungs. However A/B polarity, which is disrupted in Drosophila Scrib mutants, is largely unaffected. Notably, we find that Scrib mediates functions not attributed to other PCP proteins in the lung. Specifically, Scrib localises to both adherens and tight junctions of lung epithelia and knockdown of Scrib in lung explants and organotypic cultures leads to reduced cohesion of lung epithelial cells. Live imaging of Scrib knockdown lungs shows that Scrib does not affect bud bifurcation, as previously shown for the PCP protein Celsr1, but is required to maintain epithelial cohesion. To understand the mechanism leading to reduced cell–cell association, we show that Scrib associates with β-catenin in embryonic lung and the sub-cellular distribution of adherens and tight junction proteins is perturbed in mutant lung epithelia. Our data reveal that Scrib is required for normal lung epithelial organisation and lumen morphogenesis by maintaining cell–cell contacts. Thus we reveal novel and important roles for Scrib in lung development operating via the PCP pathway, and in regulating junctional complexes and cell cohesion.     

Bitrophic toxicity of Cry1Ac to Cycloneda sanguinea,a predator in Brazilian cotton

Insect predators are exposed to the Cry1Ac toxin in Bt cotton fields through several pathways. In this study, we investigated the effects of activated Cry1Ac added to a diet on Cycloneda sanguinea (L.) (Coleoptera: Coccinellidae), which is one of the main predators of non‐target pests in Brazilian cotton. Direct bitrophic exposure of C. sanguinea to Cry1Ac was done by feeding beetles with Aphis gossypii (Glover) (Hemiptera: Aphidae) sprayed with 500 μg per ml Cry1Ac solution. Larval and pupal survival, development time, aphid consumption, and adult longevity were recorded daily. Couples within the same experimental treatment were paired and numbers of eggs laid and hatched per female were recorded daily. Net replacement rate was calculated for each female. During development, a C. sanguinea larva consumed on average 1.8 μg of activated Cry1Ac. No significant differences due to Cry1Ac were observed for any of the response variables, except aphid consumption. Larvae receiving Cry1Ac consumed more aphids than larvae receiving distilled water alone. Additional statistical analyses were conducted to evaluate independence of responses, and for the independent responses, a simple meta‐analysis was conducted to test the null hypothesis that all responses were zero. Nearly all of the response variables were statistically independent. Two pairs of responses were not independent, but the associated multivariate tests were not significant. The meta‐analysis suggested that all effects were not different from random variation around zero and no cumulative effects could be detected. Our results indicated that bitrophic exposure to activated Cry1Ac is likely to have little or no adverse ecological effect on C. sanguinea.