Structural Rearrangements Research Articles

Interannual Dynamics of Structural and Functional Characteristics of Macrophytobenthos in the Coastal Zone of a Recreational Complex (Sevastopol, Black Sea)

A comparison of the interannual (1985, 2004, and 2015) dynamics of nine structural and functional characteristics of macrophytobenthos in the coastal waters of the Victory Park (a developing recreational zone of the city of Sevastopol, including the city beach) was carried out using one-way analysis of variance (ANOVA), factor analysis, and principal component analysis (PCA) and taking into account the depth of macrophyte habitat and concentrations of mineral forms of nitrogen and phosphorus. Interannual statistically significant differences have been found for most of the analyzed variables. It has been shown that rearrangement of the macrophytobenthos structure occurs with an increase in the nutrient pressure on the water area. Perennial dominant species are replaced by physiologically active and rapidly growing ephemeral species with a developed surface; the biomass of dominant species decreases against the background of increased biomass of epiphytes and associated species. As the nutrient pressure decreases, the bottom phytocoenosis begins to recover.

Characterization of the soybean oil body interface: revealing the mechanism of changes in the interfacial protein composition, structure, and function of oil bodies extracted under different denaturation conditions

We investigated the stability and rheological properties of extracts from soybean oil bodies (OB) obtained under different denaturing conditions (heating, guanidine hydrochloride, urea, and sodium dodecyl sulfate (SDS)). Differences in the interfacial and antioxidant properties exhibited by the different compositions of interfacial proteins in the extracted OB were also assessed. SDS disrupted the interfacial structure of OB, whereas the treatments under the other three denaturing conditions effectively increased the ability of the OB proteins to form a network structure. The analysis of the secondary and tertiary structures of proteins showed that all denaturation conditions affected both hydrogen bonding and hydrophobic interactions of the protein molecules, with urea leading to the most pronounced structural unfolding and rearrangement of the OB proteins. The microstructure results of the protein indicated that the protein treated with GuHCl and urea exhibited a 'shell-like' structure and structural decomposition, which can promote the pre-encapsulation of active substances through hydrogen bonding or hydrophobic interactions. The electrophoretic results further confirmed that SDS could displace 24-kDa proteins and disrupt the original membrane structure of OB, whereas urea removed most of the extrinsic proteins. The interfacial proteins extracted from OB using the four denaturing methods were different but all had enhanced interfacial and antioxidant properties compared to the control. Therefore, the extraction of OB under different denaturation conditions facilitated the hierarchical extraction of its interfacial proteins, thereby broadening its application in the food industry.

A triplicated wheat-rye chromosome segment including several 12-OXOPHYTODIENOATE REDUCTASE III genes influences magnesium partitioning and impacts wheat performance at low magnesium supply

We previously reported a structural rearrangement between wheat (Triticum aestivum) and rye (Secale cereale) chromosomes 1BS/1RS that increased the dosage of 12-OXOPHYTODIENOATE REDUCTASE III (OPRIII) genes involved in jasmonate biosynthesis (henceforth, 1RW line), and that drastically reduced primary root growth relative to a control line with the intact 1RS chromosome (henceforth, 1RS). In this study, we show that the increased gene-dosage of this region is associated with increases in the shoot-root partitioning of magnesium (Mg). Moreover, both a CRISPR-edited 1RW line with reduced OPRIII dosage and the 1RW line treated with the jasmonate biosynthesis inhibitor ibuprofen showed reduced differences in shoot-root Mg partitioning than 1RW. The observed differences in Mg partitioning between 1RS and 1RW plants occur over a wide range of external Mg supplies and imply opposite trends of Mg accumulation in roots and shoots. Furthermore, we show an association between the increase of shoot-root Mg partitioning and increased tolerance of the 1RW line to low levels of Mg supply. In summary, our results provide evidence of the role of the jasmonate pathway on the dynamics of Mg accumulation in roots and shoots, which correlates with the performance of wheat plants under conditions of Mg scarcity.

ZnFe-LDH synthesized by seed-induced method to simultaneous enhance arsenic removal, stabilization and sludge reduction

To simultaneously enhance arsenic removal, stabilization and sludge reduction, a seed-induced method was applied to in-stiu synthesize ZnFe-LDH containing arsenic (ZnFe-As-LDH). The optimal seed was determined to be ZnFe-LDH by analyzing the effects of the unseeded system and seed-induced system (FeⅡFeⅢ-LDH, ferrihydrite and ZnFe-LDH). In the ZnFe-LDH seed system, the arsenic removal efficiency increased and the arsenic leaching concentration were drastically reduced by 91.33% under the optimal conditions as the seeds dosage of 2.5g/L, pH 10 and Zn/Fe ratio of 1.5. The addition of seed crystals promoted crystal growth and aggregation and finally regulated the formation of dense bulk LDH with fewer pores and smaller pore sizes. The arsenic removal and stabilization were achieved by converting active arsenic into more stable crystalline bound arsenic through coprecipitation, ion exchange and complexation. The SV30 was reduced by 73.68% and it was due to reduction of unstable surface water and interspace and crystallinity enhancement. The formation pathway of ZnFe-As-LDH by seed-induced was elucidated. The seed-induced method promoted the formation of arsenic-containing ferrihydrite and Zn(OH)2 coprecipitations on the surface of ZnFe-LDH seed, and led to a structural rearrangement to generate ZnFe-As-LDH.

Low-boiling-point perfluorocarbon nanodroplets for adaptable ultrasound-induced blood-brain barrier opening

Low-boiling point perfluorocarbon nanodroplets (NDs) are valued as effective sonosensitive agents, encapsulating a liquid perfluorocarbon that would instantaneously vaporize at body temperature without the NDs shell. Those NDs have been explored for both therapeutic and diagnostic purposes. Here, phospholipid-shelled nanodroplets containing octafluoropropane (C3F8) or decafluorobutane (C4F10) formed by condensation of microbubbles were thoroughly characterized before blood-brain (BBB) permeabilization. Transmission electron microscopy (TEM) and cryo-TEM were employed to confirm droplet formation while providing high-resolution insights into the droplet surface and lipid arrangement assessed from electron density observation after condensation. The vaporization threshold of NDs was determined with a high-speed camera, and the frequency signal emitted by the freshly vaporized bubbles was analyzed using cavitation detection. C3F8 NDs exhibited vaporization at 0.3 MPa (f0 = 1.5 MHz, 50 cycles), and emitted signals at 2 f0 and 1.5 f0 from 0.45 MPa onwards (f0 = 1.5 MHz, 50 cycles), while broadband noise was measured starting from 0.55 MPa. NDs with the higher boiling point C4F10 vaporized at 1.15 MPa and emitted signals at 2 f0 from 0.65 MPa and 1.5 f0 from 0.9 MPa, while broadband noise was detected starting from 0.95 MPa. Both ND formulations were used to permeabilize the BBB in healthy mice using tailored ultrasound sequences, allowing for the identification of optimal applications for each NDs type. C3F8 NDs proved suitable and safe for permeabilizing a large area, potentially the entire brain, at low acoustic pressure. Meanwhile, C4F10 droplets facilitated very localized (400 μm isotropic) permeabilization at higher pressure. This study prompts a closer examination of the structural rearrangements occurring during the condensation of microbubbles into NDs and highlight the potential to tailor solutions for different brain pathologies by choosing the composition of the NDs and adjusting the ultrasound sequence.

Hydrogen-Deuterium Exchange Mass Spectrometry Reveals Mechanistic Insights into RNA Oligonucleotide-Mediated Inhibition of TDP-43 Aggregation.

Deposits of aggregated TAR DNA-binding protein 43 (TDP-43) in the brain are associated with several neurodegenerative diseases. It is well established that binding of RNA/DNA to TDP-43 can prevent TDP-43 aggregation, but an understanding of the structure(s) and conformational dynamics of TDP-43, and TDP-43-RNA complexes, is lacking, including knowledge of how the solution environment modulates these properties. Here, we address this challenge using hydrogen-deuterium exchange-mass spectrometry. In the presence of RNA olignoucleotides, we observe protection from exchange in the RNA recognition motif (RRM) domains of TDP-43 and the linker region between the RRM domains, consistent with nucleic acid binding modulating interdomain interactions. Intriguingly, at elevated salt concentrations, the extent of protection from exchange is reduced in the RRM domains when bound to an RNA sequence derived from the 3' UTR of the TDP-43 mRNA (CLIP34NT) compared to when bound to a (UG)6 repeat sequence. Under these conditions, CLIP34NT is no longer able to prevent TDP-43 aggregation. This suggests that a salt-induced structural rearrangement occurs when bound to this RNA, which may play a role in facilitating aggregation. Additionally, upon RNA binding, we identify differences in exchange within the short α-helical region located in the C-terminal domain (CTD) of TDP-43. These allosterically altered regions may influence the ability of TDP-43 to aggregate and fine-tune its RNA binding repertoire. Combined, these data provide additional insights into the intricate interplay between TDP-43 aggregation and RNA binding, an understanding of which is crucial for unraveling the molecular mechanisms underlying TDP-43-associated neurodegeneration.

Exploring Bias in GPCR Signaling and its Implication in Drug Development: A One-Sided Affair.

G protein-coupled receptors (GPCRs) play a pivotal role in regulating numerous physiological processes through their interactions with two key effectors: G proteins and β-arrestins (βarrs). This makes them crucial targets for therapeutic drug development. Interestingly, the evolving concept of biased signaling where ligands selectively activate either the G proteins or the βarrs has not only refined our understanding of segregation of physiological responses downstream of GPCRs but has also revolutionized drug discovery, offering the potential for treatments with enhanced efficacy and minimal side effects. This Review explores the mechanisms behind biased agonism, exploring it through various lenses, including ligand, receptor, cellular systems, location, and tissue-specific biases. It also offers structural insights into both orthosteric and allosteric ligand-binding pockets, structural rearrangements associated with the loops, and how ligand-engineering can contribute to biased signaling. Moreover, we also discuss the unique conformational signature in an intrinsically biased GPCR, which currently remains relatively less explored and adds a new dimension in biased signaling. Lastly, we address the translational challenges and practical considerations in characterizing bias, emphasizing its therapeutic potential and the latest advancements in drug development. By designing ligands that target specific signaling pathways, biased signaling presents a transformative approach to creating safer and more effective therapies. This Review focuses on our current understanding of GPCR-biased signaling, discussing potential mechanisms that lead to bias, the effect of bias on GPCR structures at a molecular level, recent advancements, and its profound potential to drive innovation in drug discovery.

Electronic dynamics created at conical intersections and its dephasing in aqueous solution

AbstractA dynamical rearrangement in the electronic structure of a molecule can be driven by different phenomena, including nuclear motion, electronic coherence or electron correlation. Recording such electronic dynamics and identifying its fate in an aqueous solution has remained a challenge. Here, we reveal the electronic dynamics induced by electronic relaxation through conical intersections in both isolated and solvated pyrazine molecules using X-ray spectroscopy. We show that the ensuing created dynamics corresponds to a cyclic rearrangement of the electronic structure around the aromatic ring. Furthermore, we found that such electronic dynamics were entirely suppressed when pyrazine was dissolved in water. Our observations confirm that conical intersections can create electronic dynamics that are not directly excited by the pump pulse and that aqueous solvation can dephase them in less than 40 fs. These results have implications for the investigation of electronic dynamics created during light-induced molecular dynamics and shed light on their susceptibility to aqueous solvation.

Constitutive opening of the Kv7.2 pore activation gate causes KCNQ2-developmental encephalopathy

Pathogenic variants in KCNQ2 encoding Kv7.2 voltage-gated potassium channel subunits cause developmental encephalopathies (KCNQ2-encephalopathies), both with and without epilepsy. We herein describe the clinical, in vitro, and in silico features of two encephalopathy-causing variants (A317T, L318V) in Kv7.2 affecting two consecutive residues in the S6 activation gate that undergoes large structural rearrangements during pore opening; the disease-causing A356T variant in KCNQ3, paralogous to the A317T variant in KCNQ2, was also investigated. Currents through KCNQ2 mutant channels displayed increased density, hyperpolarizing shifts in activation gating, faster activation and slower deactivation kinetics, and resistance to changes in the cellular concentrations of phosphatidylinositol 4,5-bisphosphate (PIP2), a critical regulator of Kv7 channel function; all these features are consistent with a strong gain-of-function effect. An increase in the probability of single-channel opening, with no change in membrane abundance or single-channel conductance, was responsible for the observed gain-of-function effects. All-atom molecular dynamics simulations revealed that the mutations widened the inner pore gate and stabilized a constitutively open channel configuration in the closed state, with minimal effects on the open conformation. Thus, mutation-induced stabilization of the inner pore gate open configuration is a molecular pathogenetic mechanism for KCNQ2-related encephalopathies.

Vibrational Markers of a Model Circulating Metastatic Cells LLC-R9

Metastasis in oncological diseases remains one of the main reasons for negative prognosis regarding treatment. Any new data on the biophysical and biochemical characteristics of circulating metastatic cells will help to develop a concept for antimetastatic therapy. In this study, we found a number of differences in the spectroscopic and morphological features of circulating metastatic cells. FT-IR and Raman spectra cultivated by adhesive and de-adhesive methods (with the latter used as a model for metastatic cells) have shown spectroscopic features, namely in FT-IR spectra in the region of CH stretching vibrations, which are associated with structural rearrangements in the cell membrane, as well as changes in the intensity and position of the PO2− group vibration bands correlated with proliferative activity. The spectral features in the regions of OH stretching and Amide I vibrations as well as other spectral markers of the metastatic cells grown under different cultivation conditions were derived. Raman spectra showed a redistribution of the amino acid Tyr/Trp (tryptophan to tyrosine) ratio and in Tyr doublet intensity in the region of 500–900 cm−1, as well as varying glycogen levels in different cells. The spectroscopic markers are in accordance with biochemical data. CARS and confocal optical microscopy were applied to determine the state of the cells and the F-actin expression level, which turned out to be higher for adhesive cells in comparison with de-adhesive cells. The shape and the morphological properties of the cells differ drastically. The correlation of vibrational markers with biochemical data and the cytofluorometric method was discussed.

Research Progress and Outlook of Molecular Dynamics Simulation on Carbon Dioxide Applied for Methane Exploitation from Hydrates

Research progress of carbon dioxide applied for methane exploitation from hydrates is summarized, with a focus on advances in molecular dynamics simulations and their application in understanding the mechanism of carbon dioxide replacement for hydrate exploitation. The potential of carbon dioxide in enhancing energy recovery efficiency and promoting carbon capture and storage is emphasized. An overview is provided of the advancements made in utilizing carbon dioxide for methane hydrate exploitation, highlighting its significance. Subsequently, the theoretical foundations and techniques of molecular dynamics simulations are delved into, encompassing key elements such as statistical ensembles, molecular force fields, and numerical solution methods. Through simulations, various characterization parameters including mean square displacement, radial distribution functions, coordination numbers, angular order parameters, and hydrogen bonds are computed and analyzed, which are crucial for understanding the dynamic changes in hydrate structures and the replacement process. Thorough research and analysis have been conducted on the two possible and widely debated mechanisms involved in the replacement of methane hydrates by carbon dioxide, with a particular emphasis on guest molecular replacement and hydrate reconfiguration. These processes encompass the intricate interactions between carbon dioxide molecules and the cage-like structure of hydrates, as well as the rearrangement and stabilization of hydrate structures. Several key issues surrounding the application of carbon dioxide for methane hydrate exploitation are identified, including the influence of thermodynamic conditions, the selection of auxiliary gases, and other potential factors such as geological conditions and fluid properties. Addressing these issues is crucial for optimizing the extraction process and enhancing economic and environmental benefits. A theoretical foundation and technical reference for the application of carbon dioxide in methane hydrate exploitation are provided, while future research directions and priorities are also outlined.

Characterization of Mycelium Biocomposites under Simulated Weathering Conditions.

Expanded polystyrene (EPS) remains a popular packaging material despite environmental concerns such as pollution, difficulty to recycle, and toxicity to wildlife. The goal of this study is to evaluate the potential of an ecofriendly alternative to traditional EPS composed of a mycelium biocomposite grown from agricultural waste. In this material, the mycelium spores are incorporated into cellulosic waste, resulting in a structurally sound biocomposite completely enveloped by mycelium fibers. One of the main criteria for shipping applications is the ability of a material to withstand extreme weather conditions. Accordingly, this study focused on evaluating a commercially available mycelium material before and after exposure to various weathering conditions, including high and low temperatures at different humidity levels. Fourier transform infrared spectroscopy (FTIR) was performed to examine any transformations in the mycelium structure and composition, whereas scanning electron microscopy (SEM) was used to reveal any changes in the morphology. Similarly, thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC) analyses were conducted to evaluate the thermal behavior, whereas mechanical properties were measured by using shore hardness and Izod Impact testing. Although some irreversible changes were observed due to the exposure to high temperatures, the material exhibited good thermal stability and impact resistance. FTIR analysis demonstrated small changes in the biocomposite structure and protein rearrangement as a result of weathering, whereas SEM revealed some cracking in the cellulose substrate. A combination of low temperatures and humidity resulted in significant moisture absorption, as indicated by TGA and DSC. This in turn decreased the hardness of the fibers by nearly 2-fold; however, the impact strength of the entire biocomposite remained unchanged. Overall, these results provide important insight into the structure-property relationships of mycelium-based materials.

Cytological mapping of a powdery mildew resistance locus PmRc1 based on wheat-Roegneria ciliaris structural rearrangement library.

A powdery mildew (Pm) resistance locus PmRc1 was identified and transferred from Roegneria ciliaris into wheat. Two compensative translocation lines carrying PmRc1 were developed. Powdery mildew (Pm), caused by the biotrophic fungal pathogen Blumeria graminis f.sp. tritici (Bgt), is a global destructive disease of bread wheat (Triticum aestivum L.). Identifying and utilizing new Pm resistance gene(s) is the most fundamental work for disease control. Roegneria ciliaris (2n = 4 x= 28, genome ScScYcYc) is a wild relative species of cultivated wheat. In this work, we evaluated wheat-R. ciliaris disomic chromosome addition lines for Pm resistance in multiple years. The introduction of R. ciliaris chromosome 1Sc into wheat enhanced resistance. The resistance locus on 1Sc was designated as PmRc1. To cytologically map PmRc1, we induced structural rearrangements using ion irradiation and increasinghomoeologous chromosomal recombination. The identified 43 1Sc translocation or deletion lines were usedto construct 1Sc cytological bin map bymarker analysis using 111 molecular markers. Based on the Pm resistance of thecharacterized structural rearrangement lines, the PmRc1 locus was cytologically mapped to bin 1ScS-8 of 1Sc short arm, flanked by markers CMH93-2 and CMH114-1. Two compensatory chromosomal translocation lines (T1ScS 1BL and T1ScS-1AS 1AL) carrying PmRc1 were developed and assessed for theiragronomic traits. Translocation chromosome T1ScS 1BL hadenhanced Pm resistance accompanied by negative effects on grain number and single plant yield. Translocation chromosome T1ScS-1AS 1AL hadenhanced Pm resistance and increased spikelet number per spike, without any obvious negativeeffect on other tested traits. Thus, T1ScS-1AS 1AL is recommended preferentiallyused in wheat breedingfor Pm resistance.

Immobilization on chitosan triggers structural rearrangements and boosts phosphorus accumulation by the cells of the chlorophyte Lobosphaera sp. IPPAS C-2047

Immobilization on chitosan triggers structural rearrangements and boosts phosphorus accumulation by the cells of the chlorophyte Lobosphaera sp. IPPAS C-2047

Precision medicine for patients with salivary gland neoplasms: Determining the feasibility of implementing a next-generation sequencing-based RNA assay in a hospital laboratory

Objective: Diagnosing neoplasms of the salivary gland is challenging, as morphologic features of these tumors are complex, and well-defined diagnostic categories have overlapping features. Many salivary gland neoplasms are associated with recurrent genetic alterations. The utilization of RNA-based targeted next-generation sequencing (NGS) panels for the detection of cancer-driving translocations and mutations is emerging in the clinical laboratory. Our objective was to conduct a proof-of-concept study to show that in-house molecular testing of salivary gland tumors can enhance patient care by supporting morphologic diagnoses, thereby improving therapeutic strategies such as surgical options and targeted therapies. Material and Methods: Residual formalin-fixed paraffin-embedded salivary gland neoplasm specimens from a cohort of 17 patients were analyzed with the Archer FusionPlex Pan Solid Tumor v2 panel by NGS on an Illumina NextSeq550 platform. Results: We identified structural gene rearrangements and single nucleotide variants in our patient samples that have both diagnostic and treatment-related significance. These alterations included PLAG1, MAML, and MYB fusions and BRAF, CTNNB1, NRAS, and PIK3CA mutations. Conclusion: Our RNA-based NGS assay successfully detected known gene translocations and mutations associated with salivary gland neoplasms. The genetic alterations detected in these tumors demonstrated potential diagnostic, prognostic, and therapeutic value. We suggest that incorporating in-house ancillary molecular testing could greatly enhance the accuracy of salivary gland fine needle aspiration cytology and small biopsies, thereby better guiding surgical decisions and the use of targeted therapies.

How dynamic surface restructuring impacts intra-particle catalytic cooperativity.

Recent experiments indicated that nanoparticles (NPs) might efficiently catalyze multiple chemical reactions, frequently exhibiting new phenomena. One of those surprising observations is intra-particle catalytic cooperativity, when the reactions at one active site can stimulate the reactions at spatially distant sites. Theoretical explanations of these phenomena have been presented, pointing out the important role of charged hole dynamics. However, the crucial feature of nanoparticles that can undergo dynamic structural surface rearrangements, potentially affecting the catalytic properties, has not yet been accounted for. We present a theoretical study of the effect of dynamic restructuring in NPs on intra-particle catalytic cooperativity. It is done by extending the original static discrete-state stochastic framework that quantitatively evaluates the catalytic communications. The dynamic restructuring is modeled as stochastic transitions between states with different dynamic properties of charged holes. Our analysis reveals that the communication times always decrease with increasing rates of dynamic restructuring, while the communication lengths exhibit a dynamic behavior that depends on how dynamic fluctuations affect migration and death rates of charged holes. Computer simulations fully support theoretical predictions. These findings provide important insights into the microscopic mechanisms of catalysis on single NPs, suggesting specific routes to rationally design more efficient catalytic systems.

Cultured Primary Turtle Hepatocytes: A Cellular Model for The Study of Temperature and Anoxia

Turtle hepatocytes are a non-excitable model for metabolic depression during low-temperature and/or anoxic overwintering conditions. Cytoskeletal structure and mitochondrial distribution are continuously modified in cells, and we hypothesized that metabolic depression would inhibit such processes as cell attachment and spreading and promote withdrawal of cell protrusions and peripheral mitochondria. After developing a methodology for culturing painted turtle hepatocytes, maintenance of cell attachment after a media change, and 2D area, were used as indicators of structural rearrangement and spreading/volume. These were measured after incubating cells at varying temperatures and with or without the inclusion of cyanide (chemical proxy for anoxia). Experiments were performed using cells from 22°C- or 5°C-acclimated turtles. Live-cell imaging was used to monitor the effect of cyanide exposure on distribution of mitochondria. We also acclimated cultured cells from 22°C-acclimated turtles to 4°C in vitro and scored withdrawal of protrusions. Only cells isolated from 5°C-acclimated turtles and incubated at 4°C had reduced attachment to fibronectin substrate, but cyanide exposure had no effect. These cells also had a 24% smaller 2D area than those from 22°C-acclimated turtles. There was no change in mitochondrial distribution during cyanide perfusion. Finally, 4°C acclimation in vitro resulted in withdrawal of protrusions over 14 days. Taken together with the results from cells acclimated to low temperature in vivo, this suggests inhibition of structural rearrangement and protrusion stability by low temperature acclimation, but not cyanide exposure. Our cultured primary hepatocyte system will facilitate further study of the role of structural dynamics in reversible metabolic depression.

Effect of trehalose dehydration on crystal morphology and food caking during post-treatment

Morphological changes of trehalose crystals during drying and reprocessing lead to a series of post-processing problems, which result in a significant investment in production costs. In this work, the mechanism of drying temperature on the morphology and caking behavior of trehalose was investigated. When the drying temperature was too high (≥393.15 K), a large number of pores, cracks and burrs appeared on the surface of crystals. These lead to crystal fragmentation during agitated drying process. The dehydration kinetics showed that the rearrangement of the new structure after dehydration and the change of the dehydration mechanism were the reasons for the morphological changes of trehalose crystals. Caking experiments showed that the dried product exhibited higher hygroscopicity and tendency to caking. Compared with trehalose dihydrate, the product flowability decreased by 30.0 %, critical caking period decreased by 82.1 %, and caking strength increased by 13 times after high-temperature drying (413.15 K).

Animal Models of Febrile Seizures: Limitations and Recent Advances in the Field.

Febrile seizures (FSs) are defined as seizures occurring in children aged 6 months to 5 years with a background of elevated body temperature. It is one of the most common neurological disorders of childhood, emphasizing the importance of understanding the causes of FSs and their impact on the developing nervous system. However, there are significant limitations to the technologies currently available for studying the etiology and pathophysiology of seizures in humans. It is currently not possible to adequately capture the subtle molecular and structural rearrangements of the nervous system that can occur after seizures in humans. The use of animal models can be invaluable for these purposes. The most commonly used models in modern research are hyperthermic models in rats and mice aged 10-12 days. While these models can reproduce many of the characteristics of FSs, they have certain limitations. This review outlines the key considerations when working with models of FSs, provides an overview of current approaches to producing seizures in different model subjects, and presents a summary of key findings regarding morphological and functional changes in the brain and behavioral alterations that have been identified in studies using animal models of FSs.

Water in peripheral TM-interfaces of Orai1-channels triggers pore opening

The activation of the Ca2+-channel Orai1 via the physiological activator stromal interaction molecule 1 (STIM1) requires structural rearrangements within the entire channel complex involving a series of gating checkpoints. Focusing on the gating mechanism operating along the peripheral transmembrane domain (TM) 3/TM4-interface, we report here that some charged substitutions close to the center of TM3 or TM4 lead to constitutively active Orai1 variants triggering nuclear factor of activated T-cell (NFAT) translocation into the nucleus. Molecular dynamics simulations unveil that this gain-of-function correlates with enhanced hydration at peripheral TM-interfaces, leading to increased local structural flexibility of the channel periphery and global conformational changes permitting pore opening. Our findings indicate that efficient dehydration of the peripheral TM-interfaces driven by the hydrophobic effect is critical for maintaining the closed state of Orai1. We conclude that a charge close to the center of TM3 or TM4 facilitates concomitant hydration and widening of peripheral TM interfaces to trigger constitutive Orai1 pore opening to a level comparable to or exceeding that of native activated Orai1.