Temperature-sensitive poly(N-(2-hydroxypropyl)methacrylamide mono/dilactate)-coated liposomes for triggered contents release

We prepared thermosensitive poly( N-(2-hydroxypropyl)methacrylamide mono/dilactate) (pHPMA mono/dilactate) polymer and studied temperature-triggered contents release from polymer-coated liposomes. HPMA mono/dilactate polymer was synthesized with a cholesterol anchor suitable for incorporation in the liposomal bilayers and with a cloud point (CP) temperature of the polymer slightly above normal body temperature (42 degrees C). Dynamic light scattering (DLS) measurements showed that whereas the size of noncoated liposomes remained stable upon raising the temperature from 25 to 46 degrees C, polymer-coated liposomes aggregated around 43 degrees C. Also, noncoated liposomes loaded with calcein showed hardly any leakage of the fluorescent marker when heated to 46 degrees C. However, polymer-coated liposomes showed a high degree of temperature-triggered calcein release above the CP of the polymer. Likely, liposome aggregation and bilayer destabilization are triggered because of the precipitation of the thermosensitive polymer above its CP onto the liposomal bilayers, followed by permeabilization of the liposomal membrane. This study demonstrates that liposomes surface-modified with HPMA mono/dilactate copolymer are attractive systems for achieving temperature-triggered contents release.     

Climate‐induced warming imposes a threat to north European spring ecosystems

Interest in climate change effects on groundwater has increased dramatically during the last decade. The mechanisms of climate‐related groundwater depletion have been thoroughly reviewed, but the influence of global warming on groundwater‐dependent ecosystems (GDEs) remains poorly known. Here we report long‐term water temperature trends in 66 northern European cold‐water springs. A vast majority of the springs (82%) exhibited a significant increase in water temperature during 1968–2012. Mean spring water temperatures were closely related to regional air temperature and global radiative forcing of the corresponding year. Based on three alternative climate scenarios representing low (RCP2.6), intermediate (RCP6) and high‐emission scenarios (RCP8.5), we estimate that increase in mean spring water temperature in the region is likely to range from 0.67 °C (RCP2.6) to 5.94 °C (RCP8.5) by 2086. According to the worst‐case scenario, water temperature of these originally cold‐water ecosystems (regional mean in the late 1970s: 4.7 °C) may exceed 12 °C by the end of this century. We used bryophyte and macroinvertebrate species data from Finnish springs and spring‐fed streams to assess ecological impacts of the predicted warming. An increase in spring water temperature by several degrees will likely have substantial biodiversity impacts, causing regional extinction of native, cold‐stenothermal spring specialists, whereas species diversity of headwater generalists is likely to increase. Even a slight (by 1 °C) increase in water temperature may eliminate endemic spring species, thus altering bryophyte and macroinvertebrate assemblages of spring‐fed streams. Climate change‐induced warming of northern regions may thus alter species composition of the spring biota and cause regional homogenization of biodiversity in headwater ecosystems.     

Costly punishment prevails in intergroup conflict

Understanding how societies resolve conflicts between individual and common interests remains one of the most fundamental issues across disciplines. The observation that humans readily incur costs to sanction uncooperative individuals without tangible individual benefits has attracted considerable attention as a proximate cause as to why cooperative behaviours might evolve. However, the proliferation of individually costly punishment has been difficult to explain. Several studies over the last decade employing experimental designs with isolated groups have found clear evidence that the costs of punishment often nullify the benefits of increased cooperation, rendering the strong human tendency to punish a thorny evolutionary puzzle. Here, we show that group competition enhances the effectiveness of punishment so that when groups are in direct competition, individuals belonging to a group with punishment opportunity prevail over individuals in a group without this opportunity. In addition to competitive superiority in between-group competition, punishment reduces within-group variation in success, creating circumstances that are highly favourable for the evolution of accompanying group-functional behaviours. We find that the individual willingness to engage in costly punishment increases with tightening competitive pressure between groups. Our results suggest the importance of intergroup conflict behind the emergence of costly punishment and human cooperation.     

Attenuated expression of tenascin-c in ovalbumin-challenged STAT4-/- mice

Background

Asthma leads to structural changes in the airways, including the modification of extracellular matrix proteins such as tenascin-C. The role of tenascin-C is unclear, but it might act as an early initiator of airway wall remodelling, as its expression is increased in the mouse and human airways during allergic inflammation. In this study, we examined whether Th1 or Th2 cells are important regulators of tenascin-C in experimental allergic asthma utilizing mice with impaired Th1 (STAT4-/-) or Th2 (STAT6-/-) immunity.

Methods

Balb/c wildtype (WT), STAT4-/- and STAT6-/- mice were sensitized with intraperitoneally injected ovalbumin (OVA) followed by OVA or PBS airway challenge. Airway hyperreactivity (AHR) was measured and samples were collected. Real time PCR and immunohistochemistry were used to study cytokines and differences in the expression of tenascin-C. Tenascin-C expression was measured in human fibroblasts after treatment with TNF-α and IFN-γ in vitro.

Results

OVA-challenged WT mice showed allergic inflammation and AHR in the airways along with increased expression of TNF-α, IFN-γ, IL-4 and tenascin-C in the lungs. OVA-challenged STAT4-/- mice exhibited elevated AHR and pulmonary eosinophilia. The mRNA expression of TNF-α and IFN-γ was low, but the expression of IL-4 was significantly elevated in these mice. OVA-challenged STAT6-/- mice had neither AHR nor pulmonary eosinophilia, but had increased expression of mRNA for TNF-α, IFN-γ and IL-4. The expression of tenascin-C in the lungs of OVA-challenged STAT4-/- mice was weaker than in those of OVA-challenged WT and STAT6-/- mice suggesting that TNF-α and IFN-γ may regulate tenascin-C expression in vivo. The stimulation of human fibroblasts with TNF-α and IFN-γ induced the expression of tenascin-C confirming our in vivo findings.

Conclusions

Expression of tenascin-C is significantly attenuated in the airways of STAT4-/- mice, which may be due to the impaired secretion of TNF-α and IFN-γ in these mice.     

The formation of species pools: historical habitat abundance affects current local diversity

Aim Explanations of biogeographic diversity patterns have emphasized the role of large‐scale processes that determine species pools, whereas explanations of local patterns have not. We address the hypothesis that local diversity patterns are also primarily dependent on the size of the available species pools, which are expected to be large when the particular habitat type has been evolutionary more abundant, or in unproductive habitats due to shorter generation time and hence higher diversification rates. Location The Canary Islands. Methods We determined the geographic distribution and habitat requirements of all native vascular plant species in the Canary Islands. Species pools for each habitat type on particular islands were further split into two categories according to origin: either originating due to local diversification or due to natural immigration. The dependence of historical diversification and diversification rate on habitat type, area, age, altitude and distance to the mainland was tested with general linear mixed models weighed according to the Akaike information criterion. Results The largest portion of the local variation in plant species diversity was attributed to the historic (pre‐human) habitat area, although island age was also important. The diversification rate was higher in unproductive habitats of coastal scrub and summit vegetation. Main conclusion Our study supports the species pool hypothesis, demonstrating that natural local patterns of species diversity in different habitats mirror the abundance of those particular habitats in evolutionary history. It also supports the community‐level birth rate hypothesis, claiming that stressful conditions result in higher diversification rates. We conclude that much of the observed local variation in plant diversity can be attributed to the differing sizes of species pools evolved under particular habitat conditions, and that historic parameters are far more important determinants of local diversity than suggested by ecological theory.     

Trimeric form of intracellular ATP synthase subunit β of Aggregatibacter actinomycetemcomitans binds human interleukin-1β

Bacterial biofilms resist host defenses and antibiotics partly because of their decreased metabolism. Some bacteria use proinflammatory cytokines, such as interleukin (IL)-1β, as cues to promote biofilm formation and to alter virulence. Although one potential bacterial IL-1β receptor has been identified, current knowledge of the bacterial IL-1β sensing mechanism is limited. In chronic biofilm infection, periodontitis, Aggregatibacter actinomycetemcomitans requires tight adherence (tad)-locus to form biofilms, and tissue destroying active lesions contain more IL-1β than inactive ones. The effect of IL-1β on the metabolic activity of A. actinomycetemcomitans biofilm was tested using alamarBlue™. The binding of IL-1β to A. actinomycetemcomitans cells was investigated using transmission electron microscopy and flow cytometry. To identify the proteins which interacted with IL-1β, different protein fractions from A. actinomycetemcomitans were run in native-PAGE and blotted using biotinylated IL-1β and avidin-HRP, and identified using mass spectroscopy. We show that although IL-1β slightly increases the biofilm formation of A. actinomycetemcomitans, it reduces the metabolic activity of the biofilm. A similar reduction was observed with all tad-locus mutants except the secretin mutant, although all tested mutant strains as well as wild type strains bound IL-1β. Our results suggest that IL-1β might be transported into the A. actinomycetemcomitans cells, and the trimeric form of intracellular ATP synthase subunit β interacted with IL-1β, possibly explaining the decreased metabolic activity. Because ATP synthase is highly conserved, it might universally enhance biofilm resistance to host defense by binding IL-1β during inflammation.     

Synthesis, vibrational spectra and X-ray structures of copper(I) thiourea complexes

Complex formation of thiourea with copper takes place as an intermediate step in the preparation of copper sulfide thin films by spray pyrolysis starting from aqueous solutions of copper(II) chloride and thiourea. The stoichiometry of the complex and that of the resulting thin film primarily depends on the molecular ratio of the starting materials. For comparison, the structures of all copper(I) thiourea complexes found in the Cambridge Structural Database are classified in this paper. In addition, syntheses, structural (single crystal XRD also at low temperature 193 K) and spectroscopic studies (FTIR and Raman) of six copper-thiourea complexes are now reported. The copper to thiourea stoichiometric ratio is 1:3 in four of these complexes, but their structures are basically different as dimerization or polymer formation takes place depending on whether the water of crystallisation is present or absent. The structure of bis(μ-thiourea)tetrakis(thiourea)dicopper(I) dichloride dihydrate, [Cu₂(tu)₆]Cl₂ · 2H₂O (1) was determined at room and also at low temperature. Bis(μ-thiourea)tetrakis(thiourea)dicopper(I) dibromide dihydrate, [Cu₂(tu)₆]Br₂ · 2H₂O (2) is isomorphous with 1, like the anhydrous compounds chlorotris(thiourea)copper(I), [Cu(tu)₃]Cl (3) and bromotris(thiourea)copper(I), [Cu(tu)₃]Br (4) are isomorphous. In the third isomorphous pair of complexes the copper to thiourea stoichiometric ratio is 1:1, viz. chloro(thiourea)copper(I) hemihydrate, [Cu(tu)]Cl · 0.5H₂O (5) and bromo(thiourea)copper(I) hemihydrate, [Cu(tu)]Br · 0.5H₂O (6). During the preparation of chloro(thiourea)copper(I) hemihydrate (5) a reaction by product α,α^′-dithiobisformamidinium dichloride, [SC(NH₂)₂]₂Cl₂ (7) was identified and structurally characterized which made it possible to suggest a reaction path leading to complex formation.     

Dual Function of UNC-51-like Kinase 3 (Ulk3) in the Sonic Hedgehog Signaling Pathway

The Sonic hedgehog (Shh) signaling pathway controls a variety of developmental processes and is implicated in tissue homeostasis maintenance and neurogenesis in adults. Recently, we identified Ulk3 as an active kinase able to positively regulate Gli proteins, mediators of the Shh signaling in mammals. Here, we provide several lines of evidence that Ulk3 participates in the transduction of the Shh signal also independently of its kinase activity. We demonstrate that Ulk3 through its kinase domain interacts with Suppressor of Fused (Sufu), a protein required for negative regulation of Gli proteins. Sufu blocks Ulk3 autophosphorylation and abolishes its ability to phosphorylate and positively regulate Gli proteins. We show that Shh signaling destabilizes the Sufu-Ulk3 complex and induces the release of Ulk3. We demonstrate that the Sufu-Ulk3 complex, when co-expressed with Gli2, promotes generation of the Gli2 repressor form, and that reduction of the Ulk3 mRNA level in Shh-responsive cells results in higher potency of the cells to transmit the Shh signal. Our data suggests a dual function of Ulk3 in the Shh signal transduction pathway and propose an additional way of regulating Gli proteins by Sufu, through binding to and suppression of Ulk3.