Double Complex Research Articles

A gap in the recognition of two mycorrhizal factors: new insights into two LysM-type mycorrhizal receptors.

Arbuscular mycorrhizal (AM) fungi are crucial components of the plant microbiota and can form symbioses with 72% of land plants. Researchers have long known that AM symbioses have dramatic effects on plant performance and also provide multiple ecological services in terrestrial environments. The successful establishment of AM symbioses relies on the host plant recognition of the diffusible mycorrhizal (Myc) factors, lipo-chitooligosaccharides (LCOs) and chitooligosaccharides (COs). Among them, the short-chain COs such as CO4/5 secreted by AM fungi are the major Myc factors in COs. In this review, we summarize current advances, develop the concept of mycorrhizal biceptor complex (double receptor complexes for Myc-LCOs and CO4/5 in the same plant), and provide a perspective on the future development of mycorrhizal receptors. First, we focus on the distinct perception of two Myc factors by different host plant species, highlighting the essential role of Lysin-Motif (LysM)-type mycorrhizal receptors in perceiving them. Second, we propose the underlying molecular mechanisms by which LysM-type mycorrhizal receptors in various plants recognize both the Myc-LCOs and -COs. Finally, we explore future prospects for studies on the biceptor complex (Myc-LCO and -CO receptors) in dicots to facilitate the utilization of them in cereal crops (particularly in modern cultivated rice). In conclusion, our understanding of the precise perception processes during host plant interacting with AM fungi, where LysM-type mycorrhizal receptors act as recruiters, provides the tools to design biotechnological applications addressing agricultural challenges.

The effect of ingested copper on the structural and cytotoxic properties of Steatoda grossa (Theridiidae) spider silk

Spiders, assigned to macroconcentrators of heavy metals, are particularly threatened by the toxic effects of these chemicals. Until now, it has not been specified to what extent metals alter the processes proceeding in silk glands and if such changes could consequently influence the chemical and structural properties of the spun web threads. In the present study selected biological properties of Steatoda grossa (Theridiidae) silk yarn after nutritional exposure to copper at sublethal doses (0.234 mM CuSO4) were assessed. It was determined both changes in ultrastructure of ampullate glands and hunting web’s architecture as well the cytotoxic effect in model cells (fibroblasts: line ATCC® CCL–1 NCTC clone 929), that were in contact with the analyzed biomaterial. The exposure of spiders to copper caused the occurrence of apoptotic cells in the ampullate glands as well as a significant reduction in the diameter of single fibers in double and multiple connection complexes as compared with control. At both 24 and 72 h of incubation, intensification of apoptotic and necrotic processes was observed in the fibroblast cultures that were remaining in indirect contact with the webs produced by copper–contaminated individuals. In the case of fibroblasts in direct contact with silk from the copper group, a clear cytotoxic effect resulting in an increased frequency of necrosis was observed after 72 h of incubation. The results indicated that copper may change the biological properties of spider silk and compromise its biomaterial properties.

Disparate reactivity of a chiral iron(II) tetracarbene complex with organic azides.

A chiral tetra-NHC iron(II) complex and its disparate reactivity with multiple organic azides is reported. Both aryl and alkyl azides react with the iron(II) complex yielding three distinct products: an iron(IV) imide, an iron(IV) tetrazene, and a surprising and unprecedented double imide insertion complex.

Double complex salts based on tetraamminplatinum(ii) and vanadyl(iv) bisoxalate for the preparation of bimetallic Pt–V alloys

Two novel heterometallic complex salts have been synthesized, systematically investigated, and used as precursors for the Pt0.6V0.4 alloy.

Oxalatocuprate(ii) hexaammincobalt(iii) as a precursor of metastable solid solutions in the Co–Cu system

The synthesis and characterization of the double complex salts [Co(NH3)6]2[Cu(C2O4)2]3·4H2O and [Co(NH3)6]2[Cu(C2O4)2]3·6H2O was carried out. Subsequent annealing led to the formation of metastable solid solutions.

Nedestruktivní výzkum dvojitého rondelu u Uherského Ostrohu (okres Uherské Hradiště, Česká republika)

The article informs about the discovery of the remains of a circular structure called a rondel, in this case featuring a double rondel in ‘Padělky’ field near Uherský Ostroh (SE Moravia, Czech Republic) and offers the results of non-destructive methods of research performed there in 2016–2020. The double circular complex was discovered during an analysis of satellite images of the Earth’s surface and subsequently verified by geophysical prospection. The resulting magnetogram revealed two ditches interrupted by five presumptive entrances at the site, along with dozens of anomalies that can be interpreted as potential archaeological features. Multiple-phase prehistoric occupation at the site was later proved by surface surveys. Occupation of the earlier phase of the Linear Pottery culture and the Lengyel culture has been documented. The age of the rondel itself remains an open question for the time being, however; it can only be clarified by a regular excavation. The present study discusses the existing possibilities of dating from various perspectives. Besides a probable dating the rondel to the Lengyel culture, a later, Early Eneolithic or Early Bronze Age, dating cannot be ruled out either.

Asymptotics for real monotone double Hurwitz numbers

In recent years, monotone double Hurwitz numbers were introduced as a naturally combinatorial modification of double Hurwitz numbers. Monotone double Hurwitz numbers share many structural properties with their classical counterparts, such as piecewise polynomiality, while the quantitative properties of these two numbers are quite different. We consider real analogues of monotone double Hurwitz numbers and study the asymptotics for these real analogues. The key ingredient is an interpretation of real tropical covers with arbitrary splittings as factorizations in the symmetric group which generalizes the result from Guay-Paquet et al. (2016) [18]. By using the above interpretation, we consider three types of real analogues of monotone double Hurwitz numbers: real monotone double Hurwitz numbers relative to simple splittings, relative to arbitrary splittings and real mixed double Hurwitz numbers. Under certain conditions, we find lower bounds for these real analogues, and obtain logarithmic asymptotics for real monotone double Hurwitz numbers relative to arbitrary splittings and real mixed double Hurwitz numbers. In particular, under given conditions real mixed double Hurwitz numbers are logarithmically equivalent to complex double Hurwitz numbers. We construct a family of real tropical covers and use them to show that real monotone double Hurwitz numbers relative to simple splittings are logarithmically equivalent to monotone double Hurwitz numbers with specific conditions. This is consistent with the logarithmic equivalence of real double Hurwitz numbers and complex double Hurwitz numbers.

Synergy of Stag2-Cohesin Loss Results in Expansion of Npm1c-Mutant Hematopoietic Stem and Progenitor Cells

STAG2 is a member of cohesin complex that is recurrently mutated in >10 cancers and is essential in maintaining the integrity of the 3D genome partitioning structure known as topologically structural domains (TADs). Our previous work has demonstrated that depletion of various cohesin factors, including Stag2, leads to increased hematopoietic stem and progenitor population (HSPC) self-renewal and myeloid-biased differentiation. Loss of Stag2 leads to impaired sub-TADs and affects key hematopoietic transcription factors, such as PU.1, to access and engage their target genes. Yet, the extent and cooperative transformational role of Stag2-cohesin with leukemia driver mutations, such as Npm1c, remains unexplored. To determine whether Stag2-cohesin regulates leukemic 3D chromatin organization, we generated dual Stag2 Δ Npm1 c/+ murine models with tamoxifen inducible UbcCreER T2. After 4 weeks, HSPCs (LSK cells; Lin-Sca1+Kit+) are increased in Stag2 Δ Npm1 c/+ double mutant mice ( Figure 1A). Within LSK, Stag2 Δ Npm1 c/+ but not Npm1 c/+ has marked expansion of the myeloid bias MPP2 (LSK+Flk2-Cd150+Cd48+) and MPP3 (LSK+Flk2-Cd150-Cd48+) compartment. Interestingly, Stag2 Δ single mutant exhibit LSK and MPP3 expansion at 16 weeks, suggesting the early expansion of HSPC compartment is the result of Stag2 ΔNpm1 c/+ synergistic acceleration. No difference in serial replating of LSK and GMP (LSK-Cd34+FcyRII+) cells were observed between Npm1 c/+ and Stag2 Δ Npm1 c/+. However, Stag2 Δ Npm1 c/+ LSK cells had impaired reconstitution capacity and myeloid biased output in primary and secondary transplantation. To determine if the blockage is specific to Stag2-cohesin loss, we generated the Smc3/Npm1c double mutant mice, where both Stag1-cohesin and Stag2-cohesin complexes were partially depleted upon heterozygous deletion of Smc3. Interestingly, there were no changes in LSK or MPP3 population in Smc3 +/- Npm1 c/+ mice, suggesting it is specific to Stag2-cohesin loss which obstructs differentiation in Npm1 c/+ HSPC. Mechanistically, we performed bulk ATAC-seq on sorted HSC LT (LSK+Flk2-Cd150+Cd48-) and MPP3 population, as poor long-term reconstitution suggests functional alteration in HSC LT. Comparing to WT, both Stag2 Δ and Stag2 Δ Npm1 c/+ HSC LT have increased chromatin accessibility, while only Stag2 Δ Npm1 c/+ MPP3 have persistent opening of chromatin. Motif analysis of increased accessible peaks identified RUNX2, GATA3 and MEIS1 are among the increased accessible region in Stag2 Δ Npm1 c/+ MPP3, which reflects the increased myeloid output in the transplantation. Recently, various group have suggested that Npm1c directly binds to chromatin and drives the overexpression of genes, especially at HOX clusters and MEIS1. This suggests a possible synergistic mechanism which Stag2-cohesin regulates chromatin accessibility of key TF loci, which influences normal and leukemic stem and progenitor differentiation. To comprehensively profile the LSK population, we performed scRNAseq at 4 weeks post mutation activation, results showed a marked immune pathway activation in Stag2 Δ Npm1 c/+ LSK cells. To inter cell fate transition, we employed CellDancer, an RNA velocity based algorithm and found that Stag2 Δ Npm1 c/+ MPP cells have altered differentiation trajectory and delayed kinetics at MPP3 stages, suggesting a differentiation block ( Figure 1B). In conjunction with our results, we postulate that Stag2-cohesin regulates TF interactions with regulatory elements during cell fate transitions. We are currently investigating the direct interaction of Stag2-cohesin with regulatory elements in Npm1 c/+ cells and compare to WT and Stag2 Δ Npm1 c/+ cells. We will investigate the 3D genome organization of Npm1 c/+ and Stag2 Δ Npm1 c/+ cells to determine whether Stag2 loss induces the phenotypic changes via Ctcf-dependent or independent manner.

CO2 Hydrogenation over Fe-Co Bimetallic Catalyst Derived from the Thermolysis of [Co(NH3)6][Fe(CN)6

Reducing the amount of CO2 in the atmosphere is a very important task. Therefore, the development and search for new approaches to the synthesis of catalytic systems, allowing for the catalytic conversion of CO2 into valuable products, is an urgent task. In this work, the catalyst was obtained by the thermolysis of a double complex compound. In this regard, kinetic studies of the parameters of the thermolysis process of double complex salts-[Co(NH)3]6][Fe(CN)6] were additionally determined using isoconversion and model approaches of non-isothermal kinetics. The catalyst was studied using various physicochemical methods—X-ray diffraction (XRD), infrared (IR)-spectroscopy, Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS). It was shown that, at the stage of catalyst preparation, the formation of a CoFe alloy occurred, while the surface mainly consisted of carbon in sp2-hybridization, and the metals existed in the form of spinel CoFe2O4. It was shown that catalysts based on bimetallic salts were active in the process of hydrogenation of carbon dioxide without a pre-activation stage (CO2 conversion reached 28%, with a specific activity of 4.0 µmolCO2/gMe·s). It was established that it was possible to change the selectivity of the carbon dioxide hydrogenation process by pre-treating the catalyst with hydrogen (selectivity for methane formation in the presence of an unreduced catalyst is 46.4–68.0%, whereas in the presence of a reduced catalyst it is 5.1–16.5%).

Fabrication and physical characteristics of K/W double doped BiFeO3 complex electro-ceramic; (Bi1/2K1/2)(Fe1/2W1/2)O3

The main objective of this research work is to investigate the effect of the inclusion of potassium/tungsten (K/W) (at the Bi/Fe site) on the structural, dielectric, electrical, and optical characteristics of eco-friendly BiFeO3 to assess its potential use for multifunctional applications including energy storage. The standard solid-state reaction method was used to synthesize the desired (Bi1/2K1/2)(Fe1/2W1/2)O3 complex compound. Examination of X-ray diffraction data demonstrates the structural transformation of bismuth ferrite from rhombohedral to monoclinic on the addition of K/W. The estimated crystallite size is 52 nm. The standard cell parameters include a = 12.1967 Å, b = 9.0468 Å, c = 6.4971 Å, and β = 105.02°, resulting in a cell volume of 692.40 Å3. Analysis of Raman spectra reveals a slight alteration in intensity and displacement of Raman mode positions, attributed to the doping effect, which confirms the incorporation of K and W ions into the BiFeO3 lattice. Scanning electron microscopy provides an image indicating the dense surface structure of the sample. Elemental analysis through energy-dispersive X-ray spectroscopy verifies the presence and purity of the constituent elements. The material doped with potassium and tungsten exhibits a high dielectric constant (εr ∼ 3 × 103) and low tangent loss (tanδ ∼1). The extensive dielectric studies conducted across various frequencies and temperatures suggest that the sample possesses capacitive properties. The depression angle of 8.51° reflects the extent of deviation from Debye's behavior. The presence of hysteresis loops indicates the presence of ferroelectric behavior.

Double Intramolecular 1,2 C-H Addition of o-Methyl Groups To Form Ruthenium Pincer Double Tuck-In Complexes.

Ruthenium pincer complexes have a rich history of coordination and reaction chemistries. In this work, we report our discoveries of previously unreported Ru pincer coordination geometries. We found that mono tuck-in κ4-ArPNHPRuLCl complexes react with NaN(SiMe3)2 producing double tuck-in mer-κ5-ArPNHPRuL complexes. Interestingly, when κ4-MesPNHPRuCl is dehydrohalogenated, the resulting double tuck-in complex binds N2, forming the nitrogen complex κ5-MesPNHPRuN2. The mer-κ5-ArPNHPRuL complexes thermally isomerize to the fac-κ5-ArPNHPRuL isomers, which is an uncommon reaction for pincer complexes. The mer-κ5-ArPNHPRuL complexes react with CO and CO2 to form amide κ4-ArPNHPRu(CO)L or carbamate κ5-ArPN(CO2)PRuL complexes, respectively, supporting the hypothesis that the κ4-ArPNPRuL amide intermediates are accessible and reactive.

PdRu/SBA15 catalysts for hydrogen storage by reversible N-ethylcarbazole hydrogenation/dehydrogenation reactions

In this work, a stable double complex salt (DCS) on the surface of SBA-15 is constructed by phase transfer-assisted electrostatic adsorption method. DCS was then reduced by glow discharge plasma to obtain SBA-15 loaded PdRu bimetallic catalysts (PdRu/SBA15). The catalysts were characterized by nitrogen adsorption–desorption, TEM, FT-IR, XPS, H2-TPR and ICP-OES. The Pd anion dissolved by phase transfer is precisely adsorbed on the Ru cation, and this unique intimacy of two metals promotes the formation of stable structure. The synergistic effect of the DCS structure and the in-situ reduction of glow discharge plasma makes PdRu/SBA15 have highly dispersed and stable PdRu nanoparticles (NPs). PdRu/SBA15 is suitable for reversible hydrogen storage system. It not only catalyzed N-ethylcarbazole (NEC) hydrogenation efficiently, but also showed enhanced catalytic performance in the dehydrogenation of dodecahydro-N-ethylcarbazole (12H-NEC). The hydrogenation efficiency reached 99.8% for 80 min at 100 °C, H2 pressure of 5 Mpa and the dehydrogenation efficiency reached 100% for 6 h at 180 °C under the action of the same PdRu/SBA15 catalyst. Moreover, the catalytic activity of PdRu/SBA15 catalyst did not decrease obviously after seven cycles in reversible hydrogen storage. The reversible hydrogen storage PdRu catalysts with excellent activity has a very bright prospect in the practical application of fuel cells.

Double Complex Salts of Copper(II) Amines with the [RuNOCl5]2– Anion: Synthesis, Structure, Properties

Double Complex Salts of Copper(II) Amines with the [RuNOCl5]2– Anion: Synthesis, Structure, Properties

The structural mechanism of dimeric DONSON in replicative helicase activation

The MCM motor of the replicative helicase is loaded onto origin DNA as an inactive double hexamer before replication initiation. Recruitment of activators GINS and Cdc45 upon S-phase transition promotes the assembly of two active CMG helicases. Although work with yeast established the mechanism for origin activation, how CMG is formed in higher eukaryotes is poorly understood. Metazoan Downstream neighbor of Son (DONSON) has recently been shown to deliver GINS to MCM during CMG assembly. What impact this has on the MCM double hexamer is unknown. Here, we used cryoelectron microscopy (cryo-EM) on proteins isolated from replicating Xenopus egg extracts to identify a double CMG complex bridged by a DONSON dimer. We find that tethering elements mediating complex formation are essential for replication. DONSON reconfigures the MCM motors in the double CMG, and primordial dwarfism patients' mutations disrupting DONSON dimerization affect GINS and MCM engagement in human cells and DNA synthesis in Xenopus egg extracts.

Evaluation of viability, physicochemical properties, and digestibility of freeze-dried Weissella cibaria microcapsules during storage

The objective of the investigation was to evaluate the viability, physicochemical properties, and stability of freeze-dried Weissella cibaria microcapsules in gastric and intestinal juices. W. cibaria microcapsules obtained by integrated technologies of double emulsion and complex coacervation were lyophilized and evaluated during storage at temperatures (5, 15, and 25 °C) and time (1, 2, 3, 4, 5, and 6 months). Dependent variables were evaluated: water activity (aw), moisture (Xw), solubility, hygroscopicity, peroxide index (PI), viability and simulated in vitro gastrointestinal digestion (SGD). Capsules stored at 5 °C retained the highest viability at 180 days of storage (7.8 ± 0.1 Log10 CFU g−1), ensuring adequate physicochemical properties: aw (0.507 ± 0.003), Xw (3.4 ± 0.1 %), solubility (33.1 ± 1.3 %), hygroscopicity (1.2 ± 0.3 %), PI (3.8 ± 0.1 meqO2 kg−1). While, at 25 °C viability reached 6.5 ± 0.1 Log10 CFU g−1. In general, it is highlighted that at the 3 temperatures, the probiotic character of the W. cibaria microcapsules is maintained during the 6 months of storage, which guarantees the effectiveness of the encapsulation method.

Double pseudo-polymeric complexes of [Au(S2CNR2)2][TlCl4], R2 = (CH2)5, (CH2)6: preparation, structural organization, and thermal behavior (low-temperature reduction and crystallization of gold)

The capability of thallium(I) alkylenedithiocarbamates to bind gold(III) from solutions in 2 M HCl was studied. Double complexes of [Au{S2CN(CH2)5}2][TlCl4] and [Au{S2CN(CH2)6}2][TlCl4] were preparatively isolated as individual forms of gold(III) binding into the solid phase. In the crystalline state, the ionic structural units of the complexes are combined together due to the secondary Au···S, Tl···S and S···Cl bonds that results in complicated supramolecular architectures. Thermal behavior of compounds was studied using the simultaneous thermal analysis technique; both reduced elemental gold and thallium(I) chloride were identified as the final thermolysis products.

Double Pseudo-Polymeric Complexes of [Au(S2CNR2)2][TlCl4], R2 = (CH2)5, (CH2)6: Preparation, Structural Organization, and Thermal Behavior (Low-Temperature Reduction and Crystallization of Gold)

Double Pseudo-Polymeric Complexes of [Au(S2CNR2)2][TlCl4], R2 = (CH2)5, (CH2)6: Preparation, Structural Organization, and Thermal Behavior (Low-Temperature Reduction and Crystallization of Gold)

Palladium-Rhenium Catalysts for Selective Hydrogenation of Furfural: Influence of Catalyst Preparation on Structure and Performance

PdRe/Al2O3 catalysts are highly selective for hydrogenation of furfural to furfuryl alcohol (FAL). Moreover, the synergy between the metals can result in greater specific activity (higher turnover frequency, TOF) than exhibited by either metal alone. Bimetallic catalyst structure depends strongly on the metal precursors employed and their addition sequence to the support. In this work, PdRe/Al2O3 catalysts were prepared by: (i) co-impregnation (CI) and sequential impregnation (SI) of γ-Al2O3 using HReO4 and Pd(NO3)2, (ii) SI using NH4ReO4 and [Pd(NH3)4(NO3)2], (iii) HReO4 addition to a reduced and passivated Pd/Al2O3 catalyst, and (iv) impregnation with the double complex salt (DCS), [Pd(NH3)4(ReO4)2]. Raman spectroscopy and temperature-programmed reduction (TPR) evidence larger supported PdO crystallites in catalysts prepared using Pd(NO3)2 than [Pd(NH3)4(NO3)2]. Surface [ReO4]− species detected by Raman exhibit TPR peak temperatures from ranging 85 to 260 °C (versus 375 °C for Re/Al2O3). After H2 reduction at 400 °C, the catalysts were characterized by chemisorption, temperature-programmed hydride decomposition (TPHD), CO diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), and scanning transmission electron microscopy (STEM) with energy-dispersive x-ray (EDX) spectroscopy. The CI catalyst containing supported Pd–Re alloy crystallites had a TOF similar to Pd/Al2O3 but higher (61%) FAL selectivity. In contrast, catalysts prepared by methods (ii–iv) containing supported Pd-Re nanoparticles exhibit higher TOFs and up to 78% FAL selectivity.

Dynamic Behavior and Ligand Binding Properties of the Wild Type Deoxycytidine Kinase and its Characterized Gemcitabine-Resistant Variant: A Bioinformatics and Computational Study

The main challenge in using gemcitabine, a nucleoside analogue anti-cancer, includes resistance of some patients to this compound due to the genetic mutations on deoxycytidine kinase (dCK) that are found in a fraction of the human population. Here, we investigated the dynamics behavior and ligand binding properties of the wild type (WT) dCK and its characterized double mutant using a combination of bioinformatics tools and molecular dynamics (MD) simulation studies. Root-mean-square deviation (RMSD) values of the WT and mutant enzyme in complex with both ligands (deoxycytidine/gemcitabine) demonstrated that the WT enzyme forms a more stable complex with gemcitabine, as compared with its natural ligand (deoxycytidine). However, the stability of the double mutant-deoxycytidine complex is greater, when compared with gemcitabine. It was also found that Arg131 as a critical residue can affect the binding pattern of the enzyme to ligands in a manner that the WT enzyme can interact with both ligands, while, the mutant enzyme cannot establish efficient interaction with gemcitabine, and shows high affinity to deoxycytidine. These data together indicate that gemcitabine can interact with the WT enzyme in a competitive manner, while double mutant can be considered as a resistant variant against gemcitabine.

Effect of Charged Block Length Mismatch on Double Diblock Polyelectrolyte Complex Micelle Cores.

Polyelectrolyte complex micelles are hydrophilic nanoparticles that self-assemble in aqueous environments due to associative microphase separation between oppositely charged blocky polyelectrolytes. In this work, we employ a suite of physical characterization tools to examine the effect of charged block length mismatch on the equilibrium structure of double diblock polyelectrolyte complex micelles (D-PCMs) by mixing a diverse library of peptide and synthetic charged-neutral block polyelectrolytes with a wide range of charged block lengths (25-200 units) and chemistries. Early work on D-PCMs suggested that this class of micelles can only be formed from blocky polyelectrolytes with identical charged block lengths, a phenomenon referred to as chain length recognition. Here, we use salt annealing to create PCMs at equilibrium, which shows that chain length recognition, a longstanding hurdle to repeatable self-assembly from mismatched polyelectrolytes, can be overcome. Interestingly, D-PCM structure-property relationships display a range of values that vary systematically with the charged block lengths and chemical identity of constituent polyelectrolyte pairings and cannot be described by generalizable scaling laws. We discuss the interdependent growth behavior of the radius, ionic pair aggregation number, and density in the micelle core for three chemically distinct diblock pairings and suggest a potential physical mechanism that leads to this unique behavior. By comparing the results of these D-PCMs to the scaling laws recently developed for single diblock polyelectrolyte complex micelles (S-PCMs: diblock + homopolymer), we observe that D-PCM design schemes reduce the size and aggregation number and restrict their growth to a function of charged block length relative to S-PCMs. Understanding these favorable attributes enables more predictive use of a wider array of charged molecular building blocks to anticipate and control macroscopic properties of micelles spanning countless storage and delivery applications.