Host density predicts presence of cuckoo parasitism in reed warblers

In some hosts of avian brood parasites, several populations apparently escape parasitism, while others are parasitized. Many migratory specialist brood parasites like common cuckoos, Cuculus canorus , experience a short breeding season, and in order to maintain local parasite populations host densities should be sufficiently high to allow efficient nest search. However, no studies have investigated the possible effect of host density on presence of cuckoo parasitism among populations of a single host species. Here, we investigated possible predictors of common cuckoo parasitism in 16 populations of reed warblers, Acrocephalus scirpaceus , across Europe. In more detail, we quantified the effect of host density, number of host breeding pairs, habitat type, mean distance to nearest cuckoo vantage point, predation rate and latitude on the presence of cuckoo parasitism while controlling for geographical distance among study populations. Host density was a powerful predictor of parasitism. We also found a less pronounced effect of habitat type on occurrence of parasitism, while the other variables did not explain why cuckoos utilize some reed warbler populations and not others. This is the first study focusing on patterns of common cuckoo-host interactions within a specific host species on a large geographic scale. The results indicate that if host density is below a specific threshold, cuckoo parasitism is absent regardless of the state of other potentially confounding variables.     

Novel target genes and a valid biomarker panel identified for cholangiocarcinoma

Cholangiocarcinoma is notoriously difficult to diagnose, and the mortality rate is high due to late clinical presentation. CpG island promoter methylation is frequently seen in cancer development. In the present study, we aimed at identifying novel epigenetic biomarkers with the potential to improve the diagnostic accuracy of cholangiocarcinoma. Microarray data analyses of cholangiocarcinoma cell lines treated with epigenetic drugs and their untreated counterparts were compared with previously published gene expression profiles of primary tumors and with non-malignant controls. Genes responding to the epigenetic treatment that were simultaneously downregulated in primary cholangiocarcinoma compared with controls (n = 43) were investigated for their promoter methylation status in cancer cell lines from the gastrointestinal tract. Genes commonly methylated in cholangiocarcinoma cell lines were subjected to quantitative methylation-specific polymerase chain reaction in a total of 93 clinical samples (cholangiocarcinomas and non-malignant controls). CDO1, DCLK1, SFRP1 and ZSCAN18, displayed high methylation frequencies in primary tumors and were unmethylated in controls. At least one of these four biomarkers was positive in 87% of the tumor samples, with a specificity of 100%. In conclusion, the novel methylation-based biomarker panel showed high sensitivity and specificity for cholangiocarcinoma. The potential of these markers in early diagnosis of this cancer type should be further explored.     

Allergic asthmatics show divergent lipid mediator profiles from healthy controls both at baseline and following birch pollen provocation

Background

Asthma is a respiratory tract disorder characterized by airway hyper-reactivity and chronic inflammation. Allergic asthma is associated with the production of allergen-specific IgE and expansion of allergen-specific T-cell populations. Progression of allergic inflammation is driven by T-helper type 2 (Th2) mediators and is associated with alterations in the levels of lipid mediators.

Objectives

Responses of the respiratory system to birch allergen provocation in allergic asthmatics were investigated. Eicosanoids and other oxylipins were quantified in the bronchoalveolar lumen to provide a measure of shifts in lipid mediators associated with allergen challenge in allergic asthmatics.

Methods

Eighty-seven lipid mediators representing the cyclooxygenase (COX), lipoxygenase (LOX) and cytochrome P450 (CYP) metabolic pathways were screened via LC-MS/MS following off-line extraction of bronchoalveolar lavage fluid (BALF). Multivariate statistics using OPLS were employed to interrogate acquired oxylipin data in combination with immunological markers.

Results

Thirty-two oxylipins were quantified, with baseline asthmatics possessing a different oxylipin profile relative to healthy individuals that became more distinct following allergen provocation. The most prominent differences included 15-LOX-derived ω-3 and ω-6 oxylipins. Shared-and-Unique-Structures (SUS)-plot modeling showed a correlation (R² = 0.7) between OPLS models for baseline asthmatics (R²Y[cum] = 0.87, Q²[cum] = 0.51) and allergen-provoked asthmatics (R²Y[cum] = 0.95, Q²[cum] = 0.73), with the majority of quantified lipid mediators and cytokines contributing equally to both groups. Unique structures for allergen provocation included leukotrienes (LTB₄ and 6-trans-LTB₄), CYP-derivatives of linoleic acid (epoxides/diols), and IL-10.

Conclusions

Differences in asthmatic relative to healthy profiles suggest a role for 15-LOX products of both ω-6 and ω-3 origin in allergic inflammation. Prominent differences at baseline levels indicate that non-symptomatic asthmatics are subject to an underlying inflammatory condition not observed with other traditional mediators. Results suggest that oxylipin profiling may provide a sensitive means of characterizing low-level inflammation and that even individuals with mild disease display distinct phenotypic profiles, which may have clinical ramifications for disease.     

Isothermal titration calorimetry study of the polyelectrolyte complexation of xanthan and chitosan samples of different degree of polymerization

Mixing oppositely charged polyelectrolytes in aqueous solutions leads to the spontaneous formation of polyelectrolyte complexes. Here, we characterize the interaction between xanthan of two different chain lengths, a tri-glucosamine and a chitosan polymer by isothermal titration calorimetry (ITC). Analysis of the experimental thermodynamic data assuming a single set of identical sites indicated both enthalpic and entropic contributions to the overall interaction in the interaction between xanthan and tri-glucosamine. The relative contribution of entropy compared to enthalpy was found to be largest for the shortest chain length of xanthan. Using a chitosan polymer instead of tri-glucosamine gave rise to two different stages in the interaction process. A model where the first stage of the ITC curve represent an initial polyelectrolyte complexation stage followed by aggregation on further titration of chitosan to the xanthan is suggested. Ultrastructure images by applying atomic force microscopy at some selected extents of titration are consistent with the two-stage interpretation of the thermodynamic data.     

Polyelectrolyte layer interpenetration and swelling of alginate–chitosan multilayers studied by dual wavelength reflection interference contrast microscopy

Polyelectrolyte multilayers of alginate and either poly-l-lysine or chitosan have been studied with dual wavelength reflection interference contrast microscopy (DW-RICM). Alginates with different ratios of the two monomer residues, β-d-mannuronic acid (M) and -l-guluronic acid (G) were included to study possible effects of specific divalent ions selected from their ability to influence gelation of alginate. Measurements of multilayer thickness revealed the importance of the preparation conditions. The multilayer thickness was reduced with increasing ionic strength following preparation, suggesting a dominance of an ordinary screening of the alginate component. The results indicate that the interaction between alginate and chitosan are different from that between alginate and poly-l-lysine, with the latter appearing to be more of a “hit-and-stick” reaction while rearrangements during the adsorption process is occurring to a larger extent in the preparation of the chitosan–alginate multilayers.     

Rejection of Conspecific Eggs in Chaffinches: The Effect of Age and Clutch Characteristics

Previous experimental studies have found that the majority of chaffinches, Fringilla coelebs, are able to reject both non‐mimetic and mimetic cuckoo eggs and also non‐mimetic conspecific eggs. However, interestingly the frequency of rejecters of moderately mimetic conspecific eggs has been found to be only approx. 50%. We examined the possibility that acceptors of moderately mimetic conspecific eggs are first time breeders, because these individuals may lack the experience needed to reject eggs that deviate only slightly from their own eggs. Older individuals, with good knowledge of their own egg appearance, should therefore reject such eggs. We also examined the possibility that acceptors of moderately mimetic eggs have a higher intraclutch variation in egg appearance, which makes it more difficult to recognize such eggs when compared with rejecters. We obtained no support for any age‐specific pattern in rejection behaviour. Furthermore, there was no relationship between age and intraclutch variation, or intraclutch variation and rejection behaviour. As there is no evidence of intraspecific brood parasitism in this species, the rejection of any foreign eggs is most probably an adaptation to past cuckoo, Cuculus canorus, parasitism. Acceptance of good and moderately mimetic conspecific eggs is probably due to cognitive limitations, because evolution of a more fine‐tuned recognition ability is unnecessary in the absence of intraspecific brood parasitism.