Chaotic neovascularization induced by aggressive fibrosarcoma cells overexpressing S-adenosylmethionine decarboxylase

S-adenosylmethionine decarboxylase is a key enzyme in the biosynthesis of polyamines essential for cell proliferation. Overexpression of S-adenosylmethionine decarboxylase in rodent fibroblasts led to aggressive transformants (Amdc-s cells) that had unforeseen high invasive capacity in nude mice, invading rapidly from the subcutaneous injection site into the peritoneal cavity and its organs. In vitro, these cells were much more invasive than Ras-oncogene-transformed fibroblasts, or human HT-1080 fibrosarcoma and MDA-MB-231 breast cancer cells. In immunohistological characterization, Amdc-s-induced tumors showed chaotic neovascularization, with abundant pleomorphic vessel-like structures that had noncontiguous or totally missing laminin (basement membrane) and CD31 (endothelial cell) immunoreactivity. Gene expression and protein analyses of Amdc-s cells showed them to overexpress several pro-angiogenic molecules, including vascular endothelial growth factor (VEGF-A), and to exhibit profound down-regulation of the anti-angiogenic thrombospondin-1 (TSP-1). By reintroduction of TSP-1 into Amdc-s cells, the high invasiveness was efficiently inhibited in vitro. Interestingly, Amdc-s cells showed up-regulation of hepatocyte growth factor (HGF) and also expressed the MET receptor, creating thus an autocrine loop able to regulate VEGF-A and TSP-1 levels. Further, we found Amdc-s cells to express increased amounts of matrix metalloproteinase-2 (MMP-2) and the large isoform of tenascin-C (TN-C), which may also contribute to the angiogenic switch and invasiveness. Consequently, Amdc-s cells offer an excellent model to sort out the key molecules of aggressive tumor growth, and thereby help in designing rational, novel anti-vascular and other cancer therapies.     

Dark or short nights: differential latitudinal constraints in nestling provisioning patterns of a nocturnally hunting bird species

In diurnal bird species, individuals breeding at high latitudes have larger broods than at lower latitudes, which has been linked to differences in the daily time available for foraging. However, it remains unclear how latitude is linked with parental investment in nocturnal species. Here, we investigate nestling provisioning rates of male Tengmalm's owls in two populations at different latitudes (Czech Republic 50 °N; Finland 63 °N) with the help of cameras integrated into nest boxes. Clutch sizes were smaller in the Czech population (CZ: 5.1 ± 0.1; FIN: 6.6 ± 0.1), but given the higher nestling mortality in the Finnish population, the number of fledglings did not differ between the two populations (CZ: 3.5 ± 0.3; FIN: 3.9 ± 0.2). Nestling provisioning patterns varied within days, over the reproductive season and between the two sites. Males delivered most food at dusk and dawn, having peak delivery rates at sun angles of -11° to -15° at both sites, and males increased the prey delivery rates with higher nestling requirements. Given the longer nights during summer in the Czech Republic compared to Finland, Czech males only showed a small shift in their delivery peak during the night from -17° in April to -14° in July. In contrast, Finnish males shifted their peak of prey delivery from -11° in April to -1° in July. Consequently, Czech males had a longer hunting time per night around midsummer when feeding young (360 min) than Finnish males (270 min). This suggests that nocturnal owl species in northern populations are constrained by the short nights during the breeding season, which can limit the number of young they can raise. Moreover, owls in northern populations are additionally constrained through the unpredictable changes in food availability between years, and both these factors are likely to influence the reproductive investment between populations.     

Generic method for modular surface modification of cellulosic materials in aqueous medium by sequential "click" reaction and adsorption

A generic approach for heterogeneous surface modification of cellulosic materials in aqueous medium, applicable for a wide range of functionalizations, is presented. In the first step, carboxymethyl cellulose (CMC) modified with azide or alkyne functionality, was adsorbed on a cellulosic substrate, thus, providing reactive sites for azide-alkyne cycloaddition click reactions. In the second step, functional units with complementary click units were reacted on the cellulose surface, coated by the click-modified CMC. Selected model functionalizations on diverse cellulosic substrates are shown to demonstrate the generality of the approach. The concept by sequentially combining the robust physical adsorption ("physical click") and robust chemical reaction ("chemical click") allows versatile, simple, and environmentally friendly modification of a cellulosic substrate with virtually any azide- or alkyne-modified molecule and even functionalization with several types of units.     

Epitope of titin A-band-specific monoclonal antibody Tit1 5 H1.1 is highly conserved in several Fn3 domains of the titin molecule. Centriole staining in human,mouse and zebrafish cells

Background

Previously we have reported on the development of a new mouse anti-titin monoclonal antibody, named MAb Titl 5 H1.1, using the synthetic peptide N-AVNKYGIGEPLESDSVVAK-C which corresponds to an amino acid sequence in the A-region of the titin molecule as immunogen. In the human skeletal muscles, MAb Titl 5 H1.1 reacts specifically with titin in the A-band of the sarcomere and in different non-muscle cell types with nucleus and cytoplasm, including centrioles. In this report we have studied the evolutionary aspects of the binding of MAb Tit1 5 H1.1 with its target antigen (titin).

Results

We have specified the epitope area of MAb Tit1 5 H1.1 by subpeptide mapping to the hexapeptide N-AVNKYG-C. According to protein databases this amino acid sequence is located in the COOH-terminus of several different Fn3 domains of the A-region of titin molecule in many organisms, such as human being, mouse, rabbit, zebrafish (Danio rerio), and even in sea squirt (Ciona intestinalis). Our immunohisto- and cytochemical studies with MAb Tit1 5 H1.1 in human, mouse and zebrafish tissues and cell cultures showed a striated staining pattern in muscle cells and also staining of centrioles, cytoplasm and nuclei in non-muscle cells.

Conclusions

The data confirm that titin can play, in addition to the known roles in striated muscle cells also an important role in non-muscle cells as a centriole associated protein. This phenomenon is highly conserved in the evolution and is related to Fn3 domains of the titin molecule. Using titin A-band-specific monoclonal antibody MAb Tit1 5 H1.1 it was possible to locate titin in the sarcomeres of skeletal muscle cells and in the centrioles, cytoplasm and nuclei of non-muscle cells in phylogenetically so distant organisms as Homo sapiens, Mus musculus and zebrafish (Danio rerio).

     

Guardian or threat: does golden eagle predation risk have cascading effects on forest grouse?

Previous studies on intraguild predation have mainly focused on within-class assemblages, even though avian top predators may also influence mammalian mesopredator prey. By using nation-wide long-term data from Finland, northern Europe, we examined the impacts of golden eagles (Aquila chrysaetos) together with red foxes (Vulpes vulpes) and pine martens (Martes martes) on forest-dwelling herbivores, black grouse (Tetrao tetrix) and hazel grouse (Tetrastes bonasia). We hypothesized that eagles may alleviate the overall predation pressure on grouse by imposing intraguild predation risk on mesopredators. The predation impact of eagle was modelled using eagle density estimates and distance to eagle nest. Wildlife triangle counts were used as predation impact proxies of mammalian mesopredators and as measures of response in grouse. Our results show that eagle density correlated negatively with black grouse abundance indices while being positively associated with the proportion of juveniles in both grouse species, irrespective of the abundance of mesopredators. Yet, foxes and martens alone had a negative effect on the abundance indices and the proportion of young in the two grouse species. This suggests that the possible cascading effects of eagles are not mediated by decreased mesopredator numbers, but instead by fear effects. Alternatively, they may be mediated by other species than fox or marten studied here. In conclusion, we found support for the hypothesis that eagles provide protection for juvenile black and hazel grouse, whereas they are a threat for adult grouse. This important information helps us to better understand the role of avian top predators in terrestrial ecosystems.     

Agricultural Land Use Determines the Trait Composition of Ground Beetle Communities

In order to improve biological control of agricultural pests, it is fundamental to understand which factors influence the composition of natural enemies in agricultural landscapes. In this study, we aimed to understand how agricultural land use affects a number of different traits in ground beetle communities to better predict potential consequences of land-use change for ecosystem functioning. We studied ground beetles in fields with different agricultural land use ranging from frequently managed sugar beet fields, winter wheat fields to less intensively managed grasslands. The ground beetles were collected in emergence tents that catch individuals overwintering locally in different life stages and with pitfall traps that catch individuals that could have a local origin or may have dispersed into the field. Community weighted mean values for ground beetle traits such as body size, flight ability and feeding preference were estimated for each land-use type and sampling method. In fields with high land-use intensity the average body length of emerging ground beetle communities was lower than in the grasslands while the average body length of actively moving communities did not differ between the land-use types. The proportion of ground beetles with good flight ability or a carnivorous diet was higher in the crop fields as compared to the grasslands. Our study highlights that increasing management intensity reduces the average body size of emerging ground beetles and the proportion of mixed feeders. Our results also suggest that the dispersal ability of ground beetles enables them to compensate for local management intensities.     

The associations between chronotype,a healthy diet and obesity

Unhealthy diet has been associated with obesity. Evening type has been associated with unhealthier food and nutrient intake that could predict a higher risk of obesity among them as compared to morning type. However, thus far no study has examined the interrelationships between chronotype, a healthy diet and obesity. We examined whether a healthy diet mediates the association between chronotype and obesity and whether chronotype modifies the association between a healthy and obesity. The National FINRISK 2007 Study included 4421 subjects aged 25–74 years. Diet was assessed using a validated food frequency questionnaire. Baltic Sea diet score (BSDS), including nine dietary components, was used as a measure of adherence to a healthy Nordic diet. Weight, height, body fat percentage and waist circumference were measured, and body mass index values were calculated. Chronotype was assessed using a shortened version of Horne and Östberg’s morningness–eveningness questionnaire (MEQ). The sum score calculated from MEQ was either used as a continuous variable or divided into tertiles of which the lowest tertile demonstrated evening preference and the highest tertile demonstrated morning preference. A series of regression analyses were conducted to determine whether the BSDS mediates the association between chronotype and obesity. Likelihood ratio test was used to determine whether chronotype modifies the association between the BSDS and the obesity measures. After testing the interaction, chronotype-stratified analysis for the association between the BSDS and obesity measures was determined by linear regression. Generally, the evening types had lower adherence to the BSDS and were more often smokers (men), physically inactive and had lower perceived health than the other chronotypes (p < 0.05). The poorer health behavior of this group, however, was not manifested in their obesity measures, and no evidence that the BSDS would mediate the association between chronotype and obesity was found (p > 0.05). No evidence that chronotype would modify the association between the BSDS and obesity was found either (p > 0.05).     

Alien predators are more dangerous than native predators to prey populations

Alien predators are widely considered to be more harmful to prey populations than native predators. To evaluate this expectation, we conducted a meta-analysis of the responses of vertebrate prey in 45 replicated and 35 unreplicated field experiments in which the population densities of mammalian and avian predators had been manipulated. Our results showed that predator origin (native versus alien) had a highly significant effect on prey responses, with alien predators having an impact double that of native predators. Also the interaction between location (mainland versus island) and predator origin was significant, revealing the strongest effects with alien predators in mainland areas. Although both these results were mainly influenced by the huge impact of alien predators on the Australian mainland compared with their impact elsewhere, the results demonstrate that introduced predators can impose more intense suppression on remnant populations of native species and hold them further from their predator-free densities than do native predators preying upon coexisting prey.