Territory quality affects the relative importance of habitat heterogeneity and interference competition in a long‐lived territorial songbird

Density‐dependent reproduction is commonly explained by either the habitat heterogeneity (HHH) or individual adjustment (IAH) hypothesis. Under the HHH, high quality territories are assumed to be occupied first. At higher density, occupation of low‐quality territories increases due to lower availability of high‐quality territories, which reduces mean reproductive success. Alternatively, the IAH assumes that increased competition at higher densities reduces reproductive success in all territories. For birds of prey, HHH plays an important role in territorial species, and IAH in socially breeding species. To test the generality of this hypothesis, we studied the mechanism behind density dependence in raven Corvus corax, a long‐lived passerine bird, using long‐term population data from a large number of territories. Population density decreased reproduction, which was explained by increased usage of low quality territories at higher density, supporting the HHH. Density reduced reproduction in low quality territories, but not in high and intermediate quality territories. We additionally compared the explanatory power of different models describing brood size, representing IAH, HHH, or a combination of both. The best model represented a combination of both hypotheses, in which the effect of density depended on territory quality. Our conclusion that both IAH and HHH are supported can be explained by the biology of ravens, where territorial adults not only experience interference competition with other territorial adults, but also with social groups of juveniles and floaters. We conclude that the relative importance of IAH and HHH may depend on variation in territory quality and social structure.     

Gamma frailty model for linkage analysis with application to interval-censored migraine data

For many diseases, it seems that the age at onset is geneticallyinfluenced. Therefore, the age-at-onset data are often collectedin order to map the disease gene(s). The ages are often (right)censored or truncated, and therefore, many standard techniquesfor linkage analysis cannot be used. In this paper, we presenta correlated frailty model for censored survival data of siblings.The model is used for testing heritability for the age at onsetand linkage between the loci and the gene(s) that influence(s)the survival time. The model is applied to interval-censoredmigraine twin data. Heritability (obtained from the frailtiesrather than actual onset times) was estimated as 0.42; thisvalue was highly significant. The highest lod score, a scoreof 1.9, was found at the end of chromosome 19.     

Production of Resveratrol in Recombinant Microorganisms

Resveratrol production in Saccharomyces cerevisiae was compared to that in Escherichia coli. In both systems, 4-coumarate:coenzyme A ligase from tobacco and stilbene synthase from grapes were expressed. When p-coumaric acid was used as the precursor, resveratrol accumulations in the culture medium were observed to be comparable in E. coli (16 mg/liter) and yeast (6 mg/liter).     

In situ localization of transketolase activity in epithelial cells of different rat tissues and subcellularly in liver parenchymal cells.

Metabolic mapping of enzyme activities (enzyme histochemistry) is an important tool to understand (patho)physiological functions of enzymes. A new enzyme histochemical method has been developed to detect transketolase activity in situ in various rat tissues and its ultrastructural localization in individual cells. In situ detection of transketolase is important because this multifunctional enzyme has been related with diseases such as cancer, diabetes, Alzheimer's disease, and Wernicke-Korsakoff's syndrome. The proposed method is based on the tetrazolium salt method applied to unfixed cryostat sections in the presence of polyvinyl alcohol. The method appeared to be specific for transketolase activity when the proper control reaction is performed and showed a linear increase of the amount of final reaction product with incubation time. Transketolase activity was studied in liver, small intestine, trachea, tongue, kidney, adrenal gland, and eye. Activity was found in liver parenchyma, epithelium of small intestine, trachea, tongue, proximal tubules of kidney and cornea, and ganglion cells in medulla of adrenal gland. To demonstrate transketolase activity ultrastructurally in liver parenchymal cells, the cupper iron method was used. It was shown that transketolase activity was present in peroxisomes and at membranes of granular endoplasmic reticulum. This ultrastructural localization is similar to that of glucose-6-phosphate dehydrogenase activity, suggesting activity of the pentose phosphate pathway at these sites. It is concluded that the method developed for in situ localization of transketolase activity for light and electron microscopy is specific and allows further investigation of the role of transketolase in (proliferation of) cancer cells and other pathophysiological processes.     

High-resolution NMR structure of an RNA model system: the 14-mer cUUCGg tetraloop hairpin RNA

We present a high-resolution nuclear magnetic resonance (NMR) solution structure of a 14-mer RNA hairpin capped by cUUCGg tetraloop. This short and very stable RNA presents an important model system for the study of RNA structure and dynamics using NMR spectroscopy, molecular dynamics (MD) simulations and RNA force-field development. The extraordinary high precision of the structure (root mean square deviation of 0.3 Å) could be achieved by measuring and incorporating all currently accessible NMR parameters, including distances derived from nuclear Overhauser effect (NOE) intensities, torsion-angle dependent homonuclear and heteronuclear scalar coupling constants, projection-angle-dependent cross-correlated relaxation rates and residual dipolar couplings. The structure calculations were performed with the program CNS using the ARIA setup and protocols. The structure quality was further improved by a final refinement in explicit water using OPLS force field parameters for non-bonded interactions and charges. In addition, the 2′-hydroxyl groups have been assigned and their conformation has been analyzed based on NOE contacts. The structure currently defines a benchmark for the precision and accuracy amenable to RNA structure determination by NMR spectroscopy. Here, we discuss the impact of various NMR restraints on structure quality and discuss in detail the dynamics of this system as previously determined.     

Metabolomic and elemental profiling of melon fruit quality as affected by genotype and environment

Melon (Cucumis melo L.) is a global crop in terms of economic importance and nutritional quality. The aim of this study was to explore the variability in metabolite and elemental composition of several commercial varieties of melon in various environmental conditions. Volatile and non-volatile metabolites as well as mineral elements were profiled in the flesh of mature fruit, employing a range of complementary analytical technologies. More than 1,000 metabolite signatures and 19 mineral elements were determined. Data analyses revealed variations related to factors such as variety, growing season, contrasting agricultural management practices (greenhouse vs. field with or without fruit thinning) and planting date. Two hundred and ninety-one analytes discriminated two contrasting varieties, one from the var. inodorous group and the other from the var. cantaloupensis group. Two hundred and eighty analytes discriminated a short shelf-life from a mid-shelf-life variety within the var. cantaloupensis group. Three hundred and twenty-seven analytes discriminated two seasons, and two hundred and fifty-two analytes discriminated two contrasting agricultural management practices. The affected compound families greatly depended on the factor studied. The compositional variability of identified or partially identified compounds was used to study metabolite and mineral element co-regulation using correlation networks. The results confirm that metabolome and mineral element profiling are useful diagnostic tools to characterize the quality of fruits cultivated under commercial conditions. They can also provide knowledge on fruit metabolism and the mechanisms of plant response to environmental modifications, thereby paving the way for metabolomics-guided improvement of cultural practices for better fruit quality.     

Association between Exposure to HSV1 and Cognitive Functioning in a General Population of Adolescents. The TRAILS Study

Background

Infections with different herpes viruses have been associated with cognitive functioning in psychiatric patients and healthy adults. The aim of this study was to find out whether antibodies to different herpes viruses are prospectively associated with cognitive functioning in a general adolescent population.

Methods

This study was performed in TRAILS, a large prospective general population cohort (N = 1084, 54% female, mean age 16.2 years (SD 0.6)). At age 16, immunoglobulin G antibodies against HSV1, HSV2, CMV and EBV were measured next to high sensitive C-Reactive Protein (hsCRP). Two years later, immediate memory and executive functioning were assessed using the 15 words task and the self ordered pointing task. Multiple linear regression analysis with bootstrapping was performed to study the association between viral infections and cognitive function, adjusting for gender, socioeconomic status, ethnicity, and cannabis use.

Results

Presence of HSV1 antibodies was associated with memory function ((B = −0.272, 95% CI = −0.556 to −0.016, p = 0.047)), while the association with executive functioning did not reach statistical significance (B = 0.560, 95% CI is −0.053 to 1.184, p = 0.075). The level of HSV1 antibodies was associated with both memory function (B = −0.160, 95% CI = −0.280 to −0.039, p = 0.014) and executive functioning (B = 0.296, 95% CI = 0.011 to 0.578, p = 0.046). Other herpes viruses and hsCRP were not associated with cognitive functioning.

Conclusions

Both presence and level of HSV1 antibodies are prospectively associated with reduced cognitive performance in a large cohort of adolescents.