Specific Complex Research Articles

Experimental investigation of the heat transport and pressure drop in open-cell polyurethane foams

Foam-like materials have a large specific surface area and complex structure that promotes flow turbulence, which makes them useful for heat transfer. In the literature, heat transfer in metal foams (MF) with high thermal conductivity is mainly considered. In the present paper, an experimental study of the hydraulic and heat transfer characteristics of a rectangular channel filled with polyurethane foam (PUF) inserts with a thermal conductivity of 0.2 W⋅m−1⋅K−1 in the air flow was carried out. The open-cell PUF samples had 20 and 80 pores per inch (PPI), 0.97 and 0.98 porosity, 269 µm and 60 µm fiber diameter, respectively. The Reynolds number, based on the fiber diameter ranged from 0.04 to 50. From the results of hydraulic tests, friction coefficients were determined based on the fiber diameter and permeability. The Forchheimer coefficient was 0.198 and 0.318 for 20 and 80 PPI samples, respectively. The permeability was 1.889 10−7 ⋅m2 and 7.535 10−9 ⋅m2 for 20 and 80 PPI samples, respectively. The Nusselt number for both tested PUF samples was correlated with the Reynolds number based on the fiber diameter in a power law with the Reynolds number exponent and constant equal to 0.61 and 0.037 respectively. The intensity of heat transfer in the PUF samples was 7–12 times lower than that in MF. However, a significant heat transfer enhancement is still possible compared to the empty channel up to 7 times. The heat transfer performance of PUF was higher compared to the empty channel, but the thermal performance factor was lower than one. Nevertheless, in practical situations where the mass or cost of the heat exchanger is preferable, PUF can be considered as a heat transfer intensifier.

The population of the middle course of the Ural River in the Early Iron Age (by the data from the Industrialnaya Zona cemetery)

Presented in the publication are the craniological data on a series of early nomads of the Sarmatian type from the Industrialnaya Zona (Poyma) cemetery in the territory of Terekti District of Western Kazakhstan Oblast. Age and sex determinations were given for 61 burials of the Early Iron Age and five of the Bronze Age. The cra-niological series is represented by 32 crania, of which 20 are male and 12 are female. They are characterized by similar morphological features characteristic of the population of the Ural River Basin. As of today, this series is one of the largest, and it dates to a rather narrow chronological period of the 4th–3rd cс. BC. The ‘Sauromato-Sarmatian’ population across the whole territory of its settlement demonstrates biological unity, which is also con-firmed by the palaeogenetic data. It is likely that the Volga-Ural and Cisaral regions constituted the hearth of the racial genesis, which is associated with the origin of the early nomads of the arid zones from the Urals to Ancient Khwarazm and from the Turgay to the Lower Don regions and the formation of the specific craniological complex, with large latitudinal characteristics of the cranium and facial region. The angles of the horizontal profiling feature significant flattening at the upper level, while at the lower level it is at the borderline between the Caucasoid and Mongoloid types with the nasal bones protruding prominently in profile. Also presented in the publication is the graphic reconstruction of the face from the cranium from burial No. 3, mound No. 10. The features presented in the physical appearance of the reconstruction reflect what the ancient nomads of the Ural River Basin looked like. The comparison of the craniological characteristics of the Industrialnaya Zone cemetery against a broad back-ground of the comparative materials, generalised from the cultures of the Early Iron Age, showed that the cranio-logical features of the group do not differ from the surrounding population with similar cultural characteristics of the Volga-Ural region, Western Kazakhstan, and the Lower Don region at the end of the 6th — 3rd c. BC.

The Glycosaminoglycan Side Chains and Modular Core Proteins of Heparan Sulphate Proteoglycans and the Varied Ways They Provide Tissue Protection by Regulating Physiological Processes and Cellular Behaviour.

This review examines the roles of HS-proteoglycans (HS-PGs) in general, and, in particular, perlecan and syndecan as representative examples and their interactive ligands, which regulate physiological processes and cellular behavior in health and disease. HS-PGs are essential for the functional properties of tissues both in development and in the extracellular matrix (ECM) remodeling that occurs in response to trauma or disease. HS-PGs interact with a biodiverse range of chemokines, chemokine receptors, protease inhibitors, and growth factors in immune regulation, inflammation, ECM stabilization, and tissue protection. Some cell regulatory proteoglycan receptors are dually modified hybrid HS/CS proteoglycans (betaglycan, CD47). Neurexins provide synaptic stabilization, plasticity, and specificity of interaction, promoting neurotransduction, neurogenesis, and differentiation. Ternary complexes of glypican-1 and Robbo-Slit neuroregulatory proteins direct axonogenesis and neural network formation. Specific neurexin-neuroligin complexes stabilize synaptic interactions and neural activity. Disruption in these interactions leads to neurological deficits in disorders of functional cognitive decline. Interactions with HS-PGs also promote or inhibit tumor development. Thus, HS-PGs have complex and diverse regulatory roles in the physiological processes that regulate cellular behavior and the functional properties of normal and pathological tissues. Specialized HS-PGs, such as the neurexins, pikachurin, and Eyes-shut, provide synaptic stabilization and specificity of neural transduction and also stabilize the axenome primary cilium of phototoreceptors and ribbon synapse interactions with bipolar neurons of retinal neural networks, which are essential in ocular vision. Pikachurin and Eyes-Shut interactions with an α-dystroglycan stabilize the photoreceptor synapse. Novel regulatory roles for HS-PGs controlling cell behavior and tissue function are expected to continue to be uncovered in this fascinating class of proteoglycan.

Regulation and role of the PP2A-B56 holoenzyme family in cancer.

Protein phosphatase 2A (PP2A) inactivation is common in cancer, leading to sustained activation of pro-survival and growth-promoting pathways. PP2A consists of a scaffolding A-subunit, a catalytic C-subunit, and a regulatory B-subunit. The functional complexity of PP2A holoenzymes arises mainly through the vast repertoire of regulatory B-subunits, which determine both their substrate specificity and their subcellular localization. Therefore, a major challenge for developing more effective therapeutic strategies for cancer is to identify the specific PP2A complexes to be targeted. Of note, the development of small molecules specifically directed at PP2A-B56α has opened new therapeutic avenues in both solid and hematological tumors. Here, we focus on the B56/PR61 family of PP2A regulatory subunits, which have a central role in directing PP2A tumor suppressor activity. We provide an overview of the mechanisms controlling the formation and regulation of these complexes, the pathways they control, and the mechanisms underlying their deregulation in cancer.

Non-stability of a bogie moving along a specific infinite complex flexibly beam-layer structure

A comprehensive investigation was conducted to analyze the vibration stability of a bogie that moves uniformly along a complexly modeled flexibly supported infinite Reddy-Bickford coupled beam system situated on a viscoelastic base. The bogie was simulated as a non-deformable body of finite length, connected through a specific system of two springs and two dampers with identical stiffness and damping, interacting with masses within a complex beam-layer system commonly encountered in technical practice. These masses, through which the bogie interacts with the high-order shear deformable beam-layer system, form part of a mechanical system consisting of a double oscillator in constant contact with the infinitely long flexible structure. As it is well-known that when the velocity of masses, such as the bogie or any other complex oscillator, exceeds the minimum velocity at which waves propagate in the beam, the system's oscillation may become unstable, it is crucial to determine the conditions and stable regions of motion that involve specific combinations of system parameters. The region of instability is identified within the parameter space of the system using the D-decomposition technique and the argument principle. A comprehensive analysis was conducted to investigate the impacts of the viscous damping in the supports of the bogie, the mass of the bogie bar, and the wheelbase on the stability of the model. The derived conclusions, focused on determining the stable regions of motion based on the considered parameters, represent a significant novelty and contribution to the research previously unknown for the motion system of a bogie along a complexly modeled flexibly supported infinite high-order shear deformable coupled beam-layer system on a viscoelastic base.

Continental Genesis of Sands of the Novolutsk Member, Sablinskaya Formation of the Middle Cambrian (Northwestern Flank of the Moscow Syneclise)

Despite the high degree of knowledge about Cambrian-Ordovician sandy sequence in the northwestern flank of the Moscow syneclise, some of its subdivisions are still poorly studied. For the first time the article provides a comprehensive lithological analysis of the textural and mineral-structural composition of the Novolutsk member sands, common in the west of the Leningrad region. This member conventionally belongs to the Sablinskaya Formation of the Middle Cambrian. Significant differences between the studied sands and the sands of other units of the formation are shown, and their analogues are found in the eastern sections of the Baltic-Ladoga glint. The lenticular occurrence, specific textural complex and coarse-medium-grained composition of the Novolutsk unit sands made it possible to prove their continental alluvial genesis and link them with the sedimentary environments of the earlier identified Putilovskaya member sands of the Sablinskaya Formation.

Characterization and multicriteria prioritization of water scarcity in sensitive urban areas for the implementation of a rain harvesting program: A case study for water-scarcity mitigation

An estimated 933 million people worldwide face water scarcity in urban environments with marginalized low-income populations. Rainwater harvesting has been proposed as an adaptable mitigation strategy to reduce water scarcity in those environments. As a case study, the present work proposes the implementation of a rainwater harvesting program aimed at the mitigation of water scarcity in highly vulnerable areas within the Metropolitan Area of Guadalajara, Mexico. The program was developed and structured based on an innovative strategy with replicable multicriteria characterization and prioritization, to allocate the rainwater harvesting systems in areas with a high sensitivity to water scarcity. The areas were selected based on territorial, hydrologic, and social parameters. The prioritization methodology was successfully applied for the selection of clusters for the allocation of domestic rainwater harvesting systems. A total of 4550 rainwater harvesting units were implemented leading to an estimated total yearly capture of 163,444.88 m3. Based on surveys a 14.2% reduction in water scarcity related diseases was observed in the participant households after 3 months of the systems’ implementation. The developed prioritization methodology offers an alternative for science-based resource allocations aimed at the resolution of specific complex challenges. This methodological approach could be adapted and replicated for other spatial-based decision-making and public policy applications. The implemented program offered an alternative for water scarcity mitigation in an urban environment and its application showed potential to improve the quality of life of the population, who benefited by increasing water access and availability.

ANALYSIS OF THE INTERCONNECTION OF STALLION SEMEN INDICATORS WITH GENETIC MARKERS OF PROTEINS

The purpose of the research was to study the associations of genetic polymorphism of proteins and enzymes of blood serum (albumin, transferrin, and esterase) on the quality of freshly obtained and cryopreserved semen of breeding stallions, taking into account their breed characteristics. The authors divided horses into four breed groups, taking into account their characteristics – riding horses, Orlov trotters, prize-winning trotters, and draft horses. A comparative assessment of 154 stallions revealed no significant differences in the quality of semen from different breed groups. For the first time, the influence coefficient (Fisher coefficient) of different genetic variants of proteins and enzymes on the semen parameters of stallions was analyzed and calculated. At the same time, the authors revealed the multidirectional effect of the same alleles of albumin, transferrin, and carboxylesterase on semen activity in different breeds. Thus, the presence of the albumin allele B (ALBB) had a positive effect on the mobility of fresh semen of stallions of riding breeds but a negative effect on stallions of Orlov trotters and draft horses. The heterozygous state of alleles revealed a positive effect on semen parameters. The analysis of variance of all examined stallions showed the highest level of the esterase locus (ESI) on the mobility of fresh semen and the albumin locus (ALBA) – on the mobility of frozen-thawed semen. The reliability of it is close to a statistically significant value. The results obtained suggest that specific gene complexes and associations with productive traits are formed in breeds under the influence of breeding. It must be taken into account as additional criteria for controlling the breeding process.

USABILITY GUIDELINES FOR DESIGNING M-HEALTH CLINICAL CODING AND GROUPING APPLICATION

The rapid progression of technology has led to web-based e-Health systems migrating to mobile device systems known as m-Health apps. Past researchers gave guidelines on the general e-Health, but the usability guidelines for m-Health apps were lacking. General guidelines are challenging to refer to when developing mobile apps with specific domains and complex functionalities. However, the absence of specific m-Health guidelines has made it challenging to design a quality and suitable app if it follows the general guidelines. Hence, specific usability guidelines for specific domains and complex functionalities apps with quality and sound research were developed to ensure the users get the best usable app. This study aims to produce a m-Health usability guideline for the clinical-based app of clinical coding and grouping for healthcare users. A total of ten participants participated in this study, which were fell into three categories; namely four industrial practitioners in the field of UI/UX, four experts with more than 20 years of experience in UI/UX and usability expertise, and two end-users, which consist of doctors and lecturers in public health and clinical coding. The data were collected through semi-structured interviews, allowing the participants to share feedbacks and comments to improve the usability guidelines and prototype for clinical coding and grouping of the m-Health app. The four participants from the expert categories had undergone usability evaluations, namely heuristic evaluations, while the two end-users’ groups had engaged in cognitive walkthroughs to improve the usability guidelines and the app’s prototype. The transcript of the interviews and usability evaluations were transcribed for thematic analysis using Nvivo software. The emerging themes were categorised into legibility and readability consisting of sub-themes font, icon, label and logo, buttons, and visual design that includes the sub-theme, theme and style, illustration and animation and colour. The emerging themes were a few vital usability components that were taken into consideration during the development of the m-Health app. The study highlights some of the usability components that were the foundation of the usability guidelines and the prototypes developed may be used by researchers and developers to develop the clinical-based m-Health app in the future. The usability guidelines and the clinical coding and grouping m-Health app prototype can be further tested towards other m-Health apps with similar features and between more experts and other wider audiences, such as older age groups and colour-blind people to produce a more robust and holistic app that is universally suited for all people. Moreover, the expansion from a medium-fidelity prototype to a high-fidelity app was also encouraged for future researchers and developers.

Revealing the SARS-CoV-2 Spike Protein and Specific Antibody Immune Complex Formation Mechanism for Precise Evaluation of Antibody Affinity.

The profound understanding and detailed evaluation of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) spike (SCoV2-S) protein and specific antibody interaction mechanism is of high importance in the development of immunosensors for COVID-19. In the present work, we studied a model system of immobilized SCoV2-S protein and specific monoclonal antibodies by molecular dynamics of immune complex formation in real time. We simultaneously applied spectroscopic ellipsometry and quartz crystal microbalance with dissipation to reveal the features and steps of the immune complex formation. We showed direct experimental evidence based on acoustic and optical measurements that the immune complex between covalently immobilized SCoV2-S and specific monoclonal antibodies is formed in two stages. Based on these findings it was demonstrated that applying a two-step binding mathematical model for kinetics analysis leads to a more precise determination of interaction rate constants than that determined by the 1:1 Langmuir binding model. Our investigation showed that the equilibrium dissociation constants (KD) determined by a two-step binding model and the 1:1 Langmuir model could differ significantly. The reported findings can facilitate a deeper understanding of antigen-antibody immune complex formation steps and can open a new way for the evaluation of antibody affinity towards corresponding antigens.

Regulation of Phosphoinositide Signaling by Scaffolds at Cytoplasmic Membranes.

Cytoplasmic phosphoinositides (PI) are critical regulators of the membrane-cytosol interface that control a myriad of cellular functions despite their low abundance among phospholipids. The metabolic cycle that generates different PI species is crucial to their regulatory role, controlling membrane dynamics, vesicular trafficking, signal transduction, and other key cellular events. The synthesis of phosphatidylinositol (3,4,5)-triphosphate (PI3,4,5P3) in the cytoplamic PI3K/Akt pathway is central to the life and death of a cell. This review will focus on the emerging evidence that scaffold proteins regulate the PI3K/Akt pathway in distinct membrane structures in response to diverse stimuli, challenging the belief that the plasma membrane is the predominant site for PI3k/Akt signaling. In addition, we will discuss how PIs regulate the recruitment of specific scaffolding complexes to membrane structures to coordinate vesicle formation, fusion, and reformation during autophagy as well as a novel lysosome repair pathway.

Competition co-immunoprecipitation reveals the interactors of the chloroplast CPN60 chaperonin machinery.

The functionality of all metabolic processes in chloroplasts depends on a balanced integration of nuclear- and chloroplast-encoded polypeptides into the plastid's proteome. The chloroplast chaperonin machinery is an essential player in chloroplast protein folding under ambient and stressful conditions, with a more intricate structure and subunit composition compared to the orthologous GroEL/ES chaperonin of Escherichia coli. However, its exact role in chloroplasts remains obscure, mainly because of very limited knowledge about the interactors. We employed the competition immunoprecipitation method for the identification of the chaperonin's interactors in Chlamydomonas reinhardtii. Co-immunoprecipitation of the target complex in the presence of increasing amounts of isotope-labelled competitor epitope and subsequent mass spectrometry analysis specifically allowed to distinguish true interactors from unspecifically co-precipitated proteins. Besides known substrates such as RbcL and the expected complex partners, we revealed numerous new interactors with high confidence. Proteins that qualify as putative substrate proteins differ from bulk chloroplast proteins by a higher content of beta-sheets, lower alpha-helical conformation and increased aggregation propensity. Immunoprecipitations targeted against a subunit of the co-chaperonin lid revealed the ClpP protease as a specific partner complex, pointing to a close collaboration of these machineries to maintain protein homeostasis in the chloroplast.

Mucosal IgA immune complex induces immunomodulatory responses in allergic airway and intestinal TH2 disease

IgA is the most abundant immunoglobulin at the mucosal surface and although its role in regulating mucosal immunity is not fully understood, its presence is associated with protection from developing allergic disease. We sought to determine the role of IgA immune complexes for therapeutic application to mucosal allergic responses. Trinitrophenol (TNP)-specific IgA immune complexes were applied, using TNP-coupled ovalbumin (OVA), to airway and gut mucosal surfaces in systemically sensitized allergic animals to regulate allergen challenge responses. Animals were assessed for both pathologic and immune-mediated responses in the lung and gut, respectively, using established mouse models. The mucosal application of IgA immune complexes in the lung and gut with TNP-OVA regulated TH2-driven allergic response in the lung and gut, reducing TH2 cytokines and mucus (lung) as well as diarrhea and temperature loss (gut), but increasing IL-10 and the number of regulatory T cells. The IgA-OVA immune complex did not alter peanut-induced anaphylaxis, indicating antigen specificity. Using OVA-specific DO.11-green fluorescent protein IL-4 reporter mouse-derived TH2-skewed cells in a transfer model demonstrated that mucosal IgA immune complex treatment reduced TH2-cell expansion and increased the number of regulatory T cells. To address a potential mechanism of action, TGF-β and IL-10 were induced in bone marrow-derived dendritic cells when they were exposed to IgA immune complex, suggesting a regulatory phenotype induced in dendritic cells that also led to an altered primary T-cell-mediated response in invitro OVA-specific assays. These studies highlight one possible mechanism of how allergen-specific IgA may provide a regulatory signal to reduce the development of allergic responses in the lung and gut.

Drosophila Adducin facilitates phase separation and function of a conserved spindle orientation complex.

Asymmetric cell division (ACD) allows stem cells to generate differentiating progeny while simultaneously maintaining their own pluripotent state. ACD involves coupling mitotic spindle orientation with cortical polarity cues to direct unequal segregation of cell fate determinants. In Drosophila neural stem cells (neuroblasts; NBs), spindles orient along an apical-basal polarity axis through a conserved complex of Partner of Inscuteable (Pins; human LGN) and Mushroom body defect (Mud; human NuMA). While many details of its function are well known, the molecular mechanics that drive assembly of the cortical Pins/Mud complex remain unclear, particularly with respect to the mutually exclusive Pins complex formed with the apical scaffold protein Inscuteable (Insc). Here we identify Hu li tai shao (Hts; human Adducin) as a direct Mud-binding protein, using an aldolase fold within its head domain (HtsHEAD) to bind a short Mud coiled-coil domain (MudCC) that is adjacent to the Pins-binding domain (MudPBD). Hts is expressed throughout the larval central brain and apically polarizes in mitotic NBs where it is required for Mud-dependent spindle orientation. In vitro analyses reveal that Pins undergoes liquid-liquid phase separation with Mud, but not with Insc, suggesting a potential molecular basis for differential assembly mechanics between these two competing apical protein complexes. Furthermore, we find that Hts binds an intact Pins/Mud complex, reduces the concentration threshold for its phase separation, and alters the liquid-like property of the resulting phase separated droplets. Domain mapping and mutational analyses implicate critical roles for both multivalent interactions (via MudCC oligomerization) and protein disorder (via an intrinsically disordered region in Hts; HtsIDR) in phase separation of the Hts/Mud/Pins complex. Our study identifies a new component of the spindle positioning machinery in NBs and suggests that phase separation of specific protein complexes might regulate ordered assembly within the apical domain to ensure proper signaling output.

Iron Oxide Nanoparticles as Anti-Virulence Factors of Gram-positive and Gram-negative Bacteria

Background: Due to their extensive use in medical therapy, iron oxide nanoparticles have recently attracted the attention of researchers in the field of increasing multi-resistance properties in bacterial pathogens. Because iron oxide nanoparticles have a high specific surface area, they can interact with bacterial surface structures and exhibit significant antibacterial activity. Objective: The current work, determined the effect of a novel anti-virulence factor agent which was created from iron oxide nanoparticles against selected gram-positive and gram-negative variant bacterial strains that were isolated and identified from elderly Iraqi patients with urinary tract infections. Methods: Seven bacterial strains (three gram-positive and four gram-negative) were tested for their (biofilm, adhesion, and hemolysis) activity using the quantitative test-tube method, glass-slide method, and by determining the hemolysis ability of bacterial isolates against previously prepared RBC, respectively. The highest virulence factors formation bacterial isolates were chosen to determine the effect of Iron-oxide nanoparticles. Previously prepared and characterized Iron- oxide nanoparticles were used as anti- (biofilm, adhesion, and hemolysis) by using specific Bacterial-Fe3O4 NPs complex with different concentrations. The Results: All these bacteria expressed their virulence factors, the highest-level biofilm formation abilities were detected in Proteus mirabilis and Staphylococcus aureus, and the highest-level adhesion activity was observed in Enterococcus faecalis and Pseudomonas aeruginosa while the highest-level hemolysis activities on human RBC were determined in Micrococcus luteus and E. coli. The effects of (Fe3O4) nanoparticles against the highest virulence factors bacterial isolates shows an increases in the biofilm formation abilities of S. aureus and P. mirabilis as well as for standard bacterial strains the anti-biofilm formation ability of (Fe3 O4) NPs against gram-positive S. aureus, Proteus mirabilis, and standard gram-negative bacteria demonstrated an in-decrease biofilm formation ability of these bacteria effective at (5000 and 10000 µg/ml). The anti-adhesion ability of (Fe3 O4) NPs against gram-positive Enterococcus faecalis, and gram-negative Pseudomonas aeruginosa determined no effect on the adhesion abilities of gram-positive and negative bacteria atall concentrations (250, 400, 500, 750 and 1000µg/ml) Finally, the effect of different concentrations of iron oxide nanoparticles on the hemolysis ability of Micrococcus luteus and Escherichia coli on RBC was determined, the highest hemolysis inhibition level was estimated in 1000 µg/ml and the less inhibition in 500 µg/ml as compared with control.

The Nanomechanical Properties of CLL Cells Are Linked to the Actin Cytoskeleton and Are a Potential Target of BTK Inhibitors.

Chronic lymphocytic leukemia (CLL) is an incurable disease characterized by an intense trafficking of the leukemic cells between the peripheral blood and lymphoid tissues. It is known that the ability of lymphocytes to recirculate strongly depends on their capability to rapidly rearrange their cytoskeleton and adapt to external cues; however, little is known about the differences occurring between CLL and healthy B cells during these processes. To investigate this point, we applied a single-cell optical (super resolution microscopy) and nanomechanical approaches (atomic force microscopy, real-time deformability cytometry) to both CLL and healthy B lymphocytes and compared their behavior. We demonstrated that CLL cells have a specific actomyosin complex organization and altered mechanical properties in comparison to their healthy counterpart. To evaluate the clinical relevance of our findings, we treated the cells in vitro with the Bruton's tyrosine kinase inhibitors and we found for the first time that the drug restores the CLL cells mechanical properties to a healthy phenotype and activates the actomyosin complex. We further validated these results in vivo on CLL cells isolated from patients undergoing ibrutinib treatment. Our results suggest that CLL cells' mechanical properties are linked to their actin cytoskeleton organization and might be involved in novel mechanisms of drug resistance, thus becoming a new potential therapeutic target aiming at the normalization of the mechanical fingerprints of the leukemic cells.

Understanding the Molecular Regulation of Serotonin Receptor 5-HTR1B-β-Arrestin1 Complex in Stress and Anxiety Disorders.

The serotonin receptor subtype 5-HTR1B is widely distributed in the brain with an important role in various behavioral implications including neurological conditions and psychiatric disorders. The neuromodulatory action of 5-HTR1B largely depends upon its arrestin mediated signaling pathway. In this study, we tried to investigate the role of unusually long intracellular loop3 (ICL3) region of the serotonin receptor 5-HTR1B in interaction with β-arrestin1 (Arr2) to compensate for the absence of the long cytoplasmic tail. Molecular modeling and docking tools were employed to obtain a suitable molecular conformation of the ICL3 region in complex with Arr2 which dictates the specific complex formation of 5-HTR1B with Arr2. This reveals the novel molecular mechanism of phosphorylated ICL3 mediated GPCR-arrestin interaction in the absence of the long cytoplasmic tail. The in-cell disulfide cross-linking experiments and molecular dynamics simulations of the complex further validate the model of 5-HTR1B-ICL3-Arr2 complex. Two serine residues (Ser281 and Ser295) within the 5-HTR1B-ICL3 region were found to be occupying the electropositive pocket of Arr2 in our model and might be crucial for phosphorylation and specific Arr2 binding. The alignment studies of these residues showed them to be conserved only across 5-HTR1B mammalian species. Thus, our studies were able to predict a molecular conformation of 5-HTR1B-Arr2 and identify the role of long ICL3 in the signaling process which might be crucial in designing targeted drugs (biased agonists) that promote GPCR-Arr2 signaling to deter the effects of stress and anxiety-like disorders.

Selective expression of light-harvesting complexes alters phospholipid composition in the intracytoplasmic membrane and core complex of purple phototrophic bacteria

Phospholipid–protein interactions play important roles in regulating the function and morphology of photosynthetic membranes in purple phototrophic bacteria. Here, we characterize the phospholipid composition of intracytoplasmic membrane (ICM) from Rhodobacter (Rba.) sphaeroides that has been genetically altered to selectively express light-harvesting (LH) complexes. In the mutant strain (DP2) that lacks a peripheral light-harvesting (LH2) complex, the phospholipid composition was significantly different from that of the wild-type strain; strain DP2 showed a marked decrease in phosphatidylglycerol (PG) and large increases in cardiolipin (CL) and phosphatidylcholine (PC) indicating preferential interactions between the complexes and specific phospholipids. Substitution of the core light-harvesting (LH1) complex of Rba. sphaeroides strain DP2 with that from the purple sulfur bacterium Thermochromatium tepidum further altered the phospholipid composition, with substantial increases in PG and PE and decreases in CL and PC, indicating that the phospholipids incorporated into the ICM depend on the nature of the LH1 complex expressed. Purified LH1–reaction center core complexes (LH1–RC) from the selectively expressing strains also contained different phospholipid compositions than did core complexes from their corresponding wild-type strains, suggesting different patterns of phospholipid association between the selectively expressed LH1–RC complexes and those purified from native strains. Effects of carotenoids on the phospholipid composition were also investigated using carotenoid-suppressed cells and carotenoid-deficient species. The findings are discussed in relation to ICM morphology and specific LH complex–phospholipid interactions.

Identification of metabolic pathways contributing to ER+ breast cancer disparities using a machine-learning pipeline

African American (AA) women in the United States have a 40% higher breast cancer mortality rate than Non-Hispanic White (NHW) women. The survival disparity is particularly striking among (estrogen receptor positive) ER+ breast cancer cases. The purpose of this study is to examine whether there are racial differences in metabolic pathways typically activated in patients with ER+ breast cancer. We collected pretreatment plasma from AA and NHW ER+ breast cancer cases (AA n = 48, NHW n = 54) and cancer-free controls (AA n = 100, NHW n = 48) to conduct an untargeted metabolomics analysis using gas chromatography mass spectrometry (GC–MS) to identify metabolites that may be altered in the different racial groups. Unpaired t-test combined with multiple feature selection and prediction models were employed to identify race-specific altered metabolic signatures. This was followed by the identification of altered metabolic pathways with a focus in AA patients with breast cancer. The clinical relevance of the identified pathways was further examined in PanCancer Atlas breast cancer data set from The Cancer Genome Atlas Program (TCGA). We identified differential metabolic signatures between NHW and AA patients. In AA patients, we observed decreased circulating levels of amino acids compared to healthy controls, while fatty acids were significantly higher in NHW patients. By mapping these metabolites to potential epigenetic regulatory mechanisms, this study identified significant associations with regulators of metabolism such as methionine adenosyltransferase 1A (MAT1A), DNA Methyltransferases and Histone methyltransferases for AA individuals, and Fatty acid Synthase (FASN) and Monoacylglycerol lipase (MGL) for NHW individuals. Specific gene Negative Elongation Factor Complex E (NELFE) with histone methyltransferase activity, was associated with poor survival exclusively for AA individuals. We employed a comprehensive and novel approach that integrates multiple machine learning and statistical methods, coupled with human functional pathway analyses. The metabolic profile of plasma samples identified may help elucidate underlying molecular drivers of disproportionately aggressive ER+ tumor biology in AA women. It may ultimately lead to the identification of novel therapeutic targets. To our knowledge, this is a novel finding that describes a link between metabolic alterations and epigenetic regulation in AA breast cancer and underscores the need for detailed investigations into the biological underpinnings of breast cancer health disparities.

Peroxidase-encapsulated Zn/Co-zeolite imidazole framework nanosheets on ZnCoO nanowire array for detecting H2O2 derived from mitochondrial superoxide anion

In this work, we have developed a nanocomposite consisting of horseradish peroxidase (HRP)-encapsulated 2D Zn–Co zeolite imidazole framework (ZIF) nanosheets strung on a ZnCoO nanowire array on a Ti support (denoted as 2D-Zn/Co-ZIF(HRP)|ZnCoO|Ti). This nanocomposite was then applied to constructing an electrochemical biosensor for detecting H2O2 derived from O2∙− released by mitochondria in living cells. This sensing platform shows excellent catalytic performance towards H2O2, attributable to the enzyme/metal-catalytic effect of HRP and Zn/Co-ZIF. The unique nano-string structure alleviates the aggregation of Zn/Co-ZIF nanosheets, readily exposes the catalytic active sites, protects the bioactivity of HRP, and reduces the charge/mass transfer pathway within Zn/Co-ZIF. The 2D-Zn/Co-ZIF(HRP)|ZnCoO|Ti biosensor offers two linear ranges of 0.2–10 μ M and 10–1100 μ M, a limit of detection of 0.082 μ M, a sensitivity of 3.3 mA mM−1 cm−2, good selectivity and stability over 40 days for H2O2 detection. After treating with specific mitochondrial complex inhibitors, the chronoamperometric results at the 2D-Zn/Co-ZIF(HRP)|ZnCoO|Ti confirmed complex I and III within the mitochondria electron transfer chain as the main electron leakage sites. This biosensor may contribute to the development of diagnostic health-care devices that shed light on the precaution and even treatment of oxidative stress diseases.