The Czech Academy of Sciences
Recent publications
Temperate plants show a rapid seasonal turnover in various leaf traits and defenses. Such trends in plant defenses can potentially drive seasonal shifts in the specialization of insect herbivores. We quantified how non-volatile leaf metabolites, inducible volatile organic compounds (VOCs), C:N ratio and leaf toughness changed between the early, middle, and late seasons in five Salicaceae species and one Salix hybrid. We also explored seasonal trends in overall trait variation among the studied plants. We tested whether seasonal changes in dietary specialization of leaf-chewing larvae and adult beetles related to changes in the studied host-plant traits. Trait turnover occurred mainly through changes in VOCs and seasonal increase in traits that directly lower herbivore feeding efficiency. The overall variation in leaf traits was highest in the early season, with seasonal intraspecific variation being 33% smaller than the variation among species sampled at one time point. Although less frequently than we expected, the two groups of insect herbivores showed seasonal changes in specialization. The significant trends in herbivore specialization included peaks in the middle season for larval specialization based on VOCs and host phylogenetic relatedness and for adult beetle specialization based on C:N ratio plus leaf toughness. The detected species-specific trends in host-plant traits, their intraspecific variability, and differential trends among insect herbivores highlight the importance of considering seasonal variation when predicting trends in plant–herbivore interactions.
This article studies patch retention time dynamics for which dispersal dynamics converge on the Ideal Free Distribution. Two types of dispersal dynamics are considered: one that assumes immigration rates are random and the second where immigration rates depend on patch distances. Emigration rates are inversely proportional to patch retention times. Both these dispersal dynamics converge to a unique and stable population distribution equilibrium. Assuming that animal distribution tracks current retention times instantaneously, retention time dynamics are modeled by the canonical equation of adaptive dynamics. This general framework is applied to two negative density-dependent patch payoff functions, hyperbolic and linear. Patch retention time dynamics are unbounded for low population densities, meaning dispersal tends to stop, and the resulting population distribution is identical to the classic Ideal Free Distribution. For higher densities, retention time dynamics converge on an equilibrium where animal dispersal is balanced in that the net dispersal stops.
Background Maternal perinatal mental health is essential for optimal brain development and mental health of the offspring. We evaluated whether maternal depression during the perinatal period and early life of the offspring might be selectively associated with altered brain function during emotion regulation and whether those may further correlate with physiological responses and the typical use of emotion regulation strategies. Methods Participants included 163 young adults (49% female, 28–30 years) from the ELSPAC prenatal birth cohort who took part in its neuroimaging follow-up and had complete mental health data from the perinatal period and early life. Maternal depressive symptoms were measured mid-pregnancy, 2 weeks, 6 months, and 18 months after birth. Regulation of negative affect was studied using functional magnetic resonance imaging, concurrent skin conductance response (SCR) and heart rate variability (HRV), and assessment of typical emotion regulation strategy. Results Maternal depression 2 weeks after birth interacted with sex and showed a relationship with greater brain response during emotion regulation in a right frontal cluster in women. Moreover, this brain response mediated the relationship between greater maternal depression 2 weeks after birth and greater suppression of emotions in young adult women (ab = 0.11, SE = 0.05, 95% CI [0.016; 0.226]). The altered brain response during emotion regulation and the typical emotion regulation strategy were also as sociated with SCR and HRV. Conclusions These findings suggest that maternal depression 2 weeks after birth predisposes female offspring to maladaptive emotion regulation skills and particularly to emotion suppression in young adulthood.
The symmetry of complex networks is a global property that has recently gained attention since MacArthur et al. 2008 showed that many real-world networks contain a considerable number of symmetries. These authors work with a very strict symmetry definition based on the network’s automorphism detecting mostly local symmetries in complex networks. The potential problem with this approach is that even a slight change in the graph’s structure can remove or create some symmetry. Recently, Liu (2020) proposed to use an approximate automorphism instead of strict automorphism. This method can discover symmetries in the network while accepting some minor imperfections in their structure. The proposed numerical method, however, exhibits some performance problems and has some limitations while it assumes the absence of fixed points and thus concentrates only on global symmetries. In this work, we exploit alternative approaches recently developed for treating the Graph Matching Problem and propose a method, which we will refer to as Quadratic Symmetry Approximator (QSA), to address the aforementioned shortcomings. To test our method, we propose a set of random graph models suitable for assessing a wide family of approximate symmetry algorithms. Although our modified method can potentially be applied to all types of symmetries, in the current work we perform optimization and testing oriented towards more global symmetries motivated by testing on the human brain.
DNA damage is a common event in cells, resulting from both internal and external factors. The maintenance of genomic integrity is vital for cellular function and physiological processes. The inadequate repair of DNA damage results in the genomic instability, which has been associated with the development and progression of various human diseases. Accumulation of DNA damage can lead to multiple diseases, such as neurodegenerative disorders, cancers, immune deficiencies, infertility and aging. This comprehensive review delves the impact of alterations in DNA damage response genes (DDR) and tries to elucidate how and to what extent the same traits modulate diverse major human diseases, such as cancer, neurodegenerative diseases, and immunological disorders. DDR is apparently the trait connecting important complex disorders in humans. However, the pathogenesis of the above disorders and diseases are different and leading to the divergent consequences. It is important to discover the switch(es) that direct further the pathogenic process either to proliferative, or degenerative diseases. Our understanding the influence of DNA damage on diverse human disorders may enable a development of the strategies to prevent, diagnose, and treat these diseases. In our article, we analysed publicly available GWAS summary statistics from the NHGRI-EBI GWAS Catalog and identified 12,009 single nucleotide polymorphisms (SNPs) associated with cancer. Among these, 119 SNPs were found in DDR pathways, exhibiting significant p-values. Additionally, we identified 44 SNPs linked to various cancer types and neurodegenerative diseases (NDDs), including four located in DDR-related genes: ATM, CUX2, and WNT3. Furthermore, 402 SNPs were associated with both cancer and immunological disorders, with two found in DDR gene RAD51B. This highlights the versatility of the DDR pathway in multifactorial diseases. However, the specific mechanisms that regulate DDR to initiate distinct pathogenic processes remain to be elucidated.
Alzheimer’s disease (AD) is the most common form of dementia. Characterized by progressive neurodegeneration, AD typically begins with mild cognitive decline escalating to severe impairment in communication and responsiveness. It primarily affects cerebral regions responsible for cognition, memory, and language processing, significantly impeding the functional independence of patients. With nearly 50 million dementia cases worldwide, a number expected to triple by 2050, the need for effective treatments is more urgent than ever. Recent insights into the association between obesity, type 2 diabetes mellitus, and neurodegenerative disorders have led to the development of promising treatments involving antidiabetic and anti-obesity agents. One such novel promising candidate for addressing AD pathology is a lipidized analogue of anorexigenic peptide called prolactin-releasing peptide (palm¹¹-PrRP31). Interestingly, anorexigenic and orexigenic peptides have opposite effects on food intake regulation, however, both types exhibit neuroprotective properties. Recent studies have also identified ghrelin, an orexigenic peptide, as a potential neuroprotective agent. Hence, we employed both anorexigenic and orexigenic compounds to investigate the common mechanisms underpinning their neuroprotective effects in a triple transgenic mouse model of AD (3xTg-AD mouse model) combining amyloid-beta (Aβ) pathology and Tau pathology, two hallmarks of AD. We treated 3xTg-AD mice for 4 months with two stable lipidized anorexigenic peptide analogues – palm¹¹-PrRP31, and liraglutide, a glucagon-like peptide 1 (GLP-1) analogue – as well as Dpr³-ghrelin, a stable analogue of the orexigenic peptide ghrelin, and using the method of immunohistochemistry and western blot demonstrate the effects of these compounds on the development of AD-like pathology in the brain. Palm¹¹-PrRP31, Dpr³-ghrelin, and liraglutide reduced intraneuronal deposits of Aβ plaque load in the hippocampi and amygdalae of 3xTg-AD mice. Palm¹¹-PrRP31 and Dpr³-ghrelin reduced microgliosis in the hippocampi, amygdalae, and cortices of 3xTg-AD mice. Palm¹¹-PrRP31 and liraglutide reduced astrocytosis in the amygdalae of 3xTg-AD mice. We propose that these peptides are involved in reducing inflammation, a common mechanism underlying their therapeutic effects. This is the first study to demonstrate improvements in AD pathology following the administration of both orexigenic and anorexigenic compounds, highlighting the therapeutic potential of food intake-regulating peptides in neurodegenerative disorders. Graphical Abstract
TiO 2 nanoparticles (NPs) are extensively used in various applications, highlighting the importance of ongoing research into their effects. This work belongs among rare whole‐body inhalation studies investigating the effects of TiO 2 NPs on mice. Unlike previous studies, the concentration of TiO 2 NPs in the inhalation chamber (130.8 μg/m ³ ) was significantly lower. This 11‐week study on mice confirmed in vivo the presence of TiO 2 NPs in lung macrophages and type II pneumocytes including their intracellular localization by using the electron microscopy and the state‐of‐the‐art methods detecting NPs' chemical identity/crystal structure, such as the energy‐dispersed X‐ray spectroscopy (EDX), cathodoluminescence (CL), and detailed diffraction pattern analysis using powder nanobeam diffraction (PNBD). For the first time in inhalation study in vivo, the alterations in erythrocyte morphology with evidence of echinocytes and stomatocytes, accompanied by iron accumulation in spleen, liver, and kidney, are reported following NP's exposure. Together with the histopathological evidence of hyperaemia in the spleen and kidney, and haemosiderin presence in the spleen, the finding of NPs containing iron might suggest the increased decomposition of damaged erythrocytes. The detection of TiO 2 NPs on erythrocytes through CL analysis confirmed their potential systemic availability. On the contrary, TiO 2 NPs were not confirmed in other organs (spleen, liver, and kidney); Ti was detected only in the kidney near the detection limit.
Biomass gasification is a renewable technology for energy storage and hydrogen production. As a model example, in an earlier paper by Hirka et al. Plasma Chem. Plasma Process. (2017) 37:947–965, the gasification process of crushed wood was numerically modelled for three different mean diameters of the feed particles in a reactor using a water and argon generated DC-plasma torch at a current of 400 A and compared with experimental data of the composition at the reactor outlet. Good agreement with experiment was obtained, however, a more extensive parametric study is desirable for more general conclusions and optimization of operating conditions, which is the subject of this paper. Here, currents of 400, 500, and 600 A and multiple mean particle diameters ranging from 0.2 to 20 mm were studied. The resulting parameters were averaged over a sufficiently long iterative process. The resulting characteristics include temperature, velocity, current field distributions, molar fraction of synthesis gas, as well as discrete phase and particle trajectories. With increasing diameter from about 1 mm, the produced synthesis gas becomes concentrated in the center of the reactor chamber. The numerical model has been created using ANSYS Fluent software.
For a Tychonoff space X by Cp(X)C_p(X) we denote the space of continuous real valued functions on X endowed with the pointwise topology, and C(X) denotes the Banach space endowed with the uniform topology provided X is compact. The classical two results characterizing compact scattered spaces in terms of C(X) and Cp(X)C_p(X) assert that a compact space X is scattered if and only if C(X) is an Asplund space (Namioka-Phelps) if and only if Cp(X)C_p(X) is a Fréchet–Urysohn space (Gerlits, Pytkeev). We provide another result of this type by showing the following Theorem: An infinite compact space X is scattered if and only if Cp(X)C_p(X) contains no closed σ\sigma -compact infinite-dimensional vector subspace if and only if Cp(X)C_p(X) contains no infinite-dimensional vector subspace admitting a fundamental sequence of bounded sets if and only if every vector subspace of Cp(X)C_p(X) is bornological. The above Theorem fails if X is nondiscrete scattered and noncompact. On the other hand, if X is a countable metric space which is not scattered, Cp(X)C_p(X) contains a closed infinite-dimensional σ\sigma -compact subspace. Moreover, if X=F×[1,ω]X=F\times [1,\omega ] and F is discrete with Fd, |F| \ge \mathfrak {d}, where d\mathfrak {d} is the dominating cardinal, then Cp(X)C_p(X) contains a closed infinite-dimensional σ\sigma -compact subspace, but if X=N×[1,ω]X=\mathbb {N}\times [1,\omega ] the corresponding space Cp(X)C_p(X) does not contain such subspaces. A variant of Theorem is also obtained characterizing infinite Tychonoff spaces X for which all compact subsets are scattered. These results are also motivated by a remarkable theorem of Velichko stating that for an infinite Tychonoff space X the space Cp(X)C_p(X) is not σ\sigma -compact. Several illustrating examples involving spaces c0c_0, \ell _{\infty } and the space Lip0(M)Lip_0(M) with the pointwise topology are provided and discussed.
Most methods for processing seismological data require a suitable velocity model characteristic for the given region being defined. This is also the case of the Reykjanes Peninsula in SW Iceland, where the REYKJANET seismic network was built to monitor local seismicity in the rift zone. At present, four previously published 1D velocity models (SIL, BRA, TRY and VOG) can potentially be used, prompting us to determine which one is the best. In order to address this issue, we arranged a contest in which all four 1D models and one additional 3D model (T3D) were entered. Uniform methodology for classifying the models was applied and included an analysis of: (i) post-localization travel-time residuals, (ii) residuals of the P-wave first-motion incidence angle and (iii) model-predicted and measured Rayleigh-wave dispersion. We discovered that no single model was unequivocally the most optimal, as the differences between them proved rather minor. A common shortcoming of all the models is the bias of the P-wave first motion incidence angle residuals, which may be a general problem for methods working with P-wave amplitudes (e.g., moment tensor solutions). The VOG model was selected with a weak preference. Finally, we propose a simple method for modifying any of the 1D models by adding a station-dependent surface layer with a vertical velocity gradient. This way, a pseudo-3D model is generated which is fully competitive with a true 3D model while retaining the simplicity of 1D ray tracing. The efficiency of this correction was demonstrated using the VOG model. The corrected VOG model provides post-localization residuals comparable with the true 3D model T3D, has zero bias in predicting the P-wave first-motion incidence angles, and agrees acceptably in predicting the Rayleigh-wave phase-velocity known from other sources. While calculations with a 3D model can be clumsy, the proposed pseudo-3D model is defined by few parameters and is very easy to use. Its applicability is limited to earthquake sources deeper than the deepest lower limit of the topmost layer below the stations.
Ticks and tick-borne diseases are a growing burden worldwide and vaccines are effective control interventions. Vaccine formulations with tick antigens such as BM86/BM95 (BM) and Subolesin (SUB) have shown reduction in tick fitness and infestation in immunized hosts. However, antigen combination is a challenging approach to improve vaccine efficacy (E) against multiple tick species. Herein, in silico and in music algorithms were integrated to model BM-SUB protein-protein interactions to apply a quantum vaccinology approach for combining protective epitopes or immunological quantum in the chimeric antigen Q38-95. Cattle immunized with Q38-95 and infested with African blue tick Rhipicephalus decoloratus showed an 82% E similar to BM86 and higher than SUB. The immune mechanisms activated in cattle in response to vaccination with Q38-95 were mediated by anti-BM/SUB antibodies that interfered with BM-SUB interactions and through activation of other innate and adaptive immune pathways. The results support modelling protein-protein interactions affecting E to identify and combine candidate protective epitopes in chimeric antigens.
We present a new covariant method of construction of the (position space) propagators in the N -dimensional (Euclidean) anti-de Sitter background for any gravitational theory with the Lagrangian that is an analytic expression in the metric, curvature, and covariant derivative. We show that the propagators (in Landau gauge) for all such theories can be expressed using the heat kernels for scalars and symmetric transverse-traceless rank-2 tensors on the hyperbolic N -space. The latter heat kernels are constructed explicitly and shown to be directly related to the former if an improved bi-scalar representation is used. Our heat kernel approach is first tested on general relativity, where we find equivalent forms of the propagators. Then it is used to obtain explicit expressions for propagators for various higher-derivative as well as infinite-derivative/nonlocal theories of gravity. As a by-product, we also provide a new derivation of the equivalent action (correcting a mistake in the original derivation) and an extension of the quadratic action to arbitrary N3{N\ge 3} N ≥ 3 dimensions.
Wade's rules are a well‐established tool for the description of the geometry of inorganic clusters. Among others, they state that a decrease or increase in charge is always accompanied by a change in the number of skeletal electron pairs (SEPs). This work reports the synthesis of the first cationic chalcogenaboranes closo‐[12‐X‐2‐IPr‐1‐EB11H10]BF4 (IPr=1,3‐(2,6‐iPr2C6H3)‐imidazole‐2‐ylidene; X=H, I; E=S, Se 3 a/b, 4 a/b) featuring the same SEP count as their neutral precursors, EB11H11, but bearing a positive charge. This ionisation significantly enhances the activity towards the electrophiles. It unlocks reactivity with very weak bases and offers the control of the regioselectivity towards hard/soft bases by the modulation of LUMO. The localisation of the positive charge within the borane cluster has been confirmed experimentally, spectroscopically and theoretically.
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3,334 members
Thibault JY. Derrien
  • Institute of Physics
Holger Kruse
  • Institute of Biophysics
Jaroslav Hlinka
  • Institute of Computer Sciences, Department of Complex Systems
Daniel Elleder
  • Institute of Molecular Genetics
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Prague, Czechia
Head of institution
prof. RNDr. Eva Zažímalová, CSc