Differential proteomic analysis demonstrates follicle fluid participate immune reaction and protein translation in yak

Background Ovarian follicle fluid (FF) as a microenvironment surrounding oocyte plays critical roles in physio-biochemical processes of follicle development and oocyte maturation. It is hypothesized that proteins in yak FF participate in the physio-biochemical pathways. The primary aims of this study were to find differentially expressed proteins (DEPs) between mature and immature FF, and to elucidating functions of the mature and immature FF in yak. Results The mature and immature FF samples were obtained from three healthy yaks that were nonpregnant, aged from four to five years, and free from any anatomical reproductive disorders. The FF samples were subjected to mass spectrometry with the isobaric tags for relative and absolute quantification (iTRAQ). The FF samples went through correlation analysis, principle component analysis, and expression pattern analysis based on quantification of the identified proteins. Four hundred sixty-three DEPs between mature and immature FF were identified. The DEPs between the mature and immature FF samples underwent gene ontology (GO), Kyoto encyclopedia of genes and genomes (KEGG), and protein-protein interaction (PPI) analysis. The DEPs highly expressed in the mature FF mainly took parts in the complement and coagulation cascades, defense response, acute-phase response, response to other organism pathways to avoid invasion of exogenous microorganisms. The complement activation pathway contains eight DEPs, namely C2, C5, C6, C7, C9, C4BPA, CFH, and MBL2. The three DEPs, CATHL4, CHGA, and PGLYRP1, take parts in defense response pathway to prevent invasion of exogenetic microorganism. The coagulation cascades pathway involves many coagulation factors, such as F7, F13A1, FGA, FGB, FGG, KLKB1, KNG1, MASP1, SERPINA1, and SERPIND1. While the DEPs highly expressed in the immature FF participated in protein translation, peptide biosynthetic process, DNA conformation change, and DNA geometric change pathways to facilitate follicle development. The translation pathway contains many ribosomal proteins, such as RPL3, RPL5, RPS3, RPS6, and other translation factors, such as EIF3J, EIF4G2, ETF1, MOV10, and NARS. The DNA conformation change and DNA geometric change involve nine DEPs, DDX1, G3BP1, HMGB1, HMGB2, HMGB3, MCM3, MCM5, MCM6, and RUVBL2. Furthermore, the expressed levels of the main DEPs, C2 and SERPIND1, were confirmed by western blot. Conclusions The differential proteomics revealed the up-regulated DEPs in mature FF take parts in immunoreaction to prevent invasion of microorganisms and the up-regulated DEPs in immature FF participate in protein synthesis, which may improve our knowledge of the follicular microenvironment and its biological roles for reproductive processes in yak. The DEPs, C2 and SERPIND1, can be considered as protein markers for mature yak follicle.

Label-Free Electrochemical Sensor for Rapid Bacterial Pathogen Detection Using Vancomycin-Modified Highly Branched Polymers

Rapid point of care tests for bacterial infection diagnosis are of great importance to reduce the misuse of antibiotics and burden of antimicrobial resistance. Here, we have successfully combined a new class of non-biological binder molecules with electrochemical impedance spectroscopy (EIS)-based sensor detection for direct, label-free detection of Gram-positive bacteria making use of the specific coil-to-globule conformation change of the vancomycin-modified highly branched polymers immobilized on the surface of gold screen-printed electrodes upon binding to Gram-positive bacteria. Staphylococcus carnosus was detected after just 20 min incubation of the sample solution with the polymer-functionalized electrodes. The polymer conformation change was quantified with two simple 1 min EIS tests before and after incubation with the sample. Tests revealed a concentration dependent signal change within an OD600 range of Staphylococcus carnosus from 0.002 to 0.1 and a clear discrimination between Gram-positive Staphylococcus carnosus and Gram-negative Escherichia coli bacteria. This exhibits a clear advancement in terms of simplified test complexity compared to existing bacteria detection tests. In addition, the polymer-functionalized electrodes showed good storage and operational stability.

Molecular insertion regulates the donor-acceptor interactions in cocrystals for the design of piezochromic luminescent materials

Developing a universal strategy to design new piezochromic luminescent materials with desirable properties remains challenging. Here, we report that insertion of a non-emissive molecule into a donor (perylene) and acceptor (TCNB) binary cocrystal can realize fine manipulation of intermolecular interactions between perylene and TCNB for desirable piezochromic luminescent properties. A continuous pressure-induced emission enhancement up to 3 GPa and a blue shift from 655 nm to 619 nm have been observed in perylene-TCNB cocrystals upon THF insertion, in contrast to the red-shifted and quenched emission observed when compressing perylene-TCNB cocrystals and other cocrystals reported earlier. By combining experiment with theory, it is further revealed that the inserted non-emissive THF forms blue-shifted H-bonds with neighboring TCNB molecules and promote a conformation change of perylene molecules upon compression, causing the blue-shifted and enhanced emission. This strategy remains valid when inserting other molecules as non-emissive component into perylene-TCNB cocrystals for abnormal piezochromic luminescent behaviors. Our strategy could also be extended to other cocrystals with different donor-acceptor components, opening a new way for designing novel piezochromic luminescent materials for future applications.

Through conformation change and charge trapping to achieve binary/ternary rewritable memory performance of carbazole-based organic molecules

To better understand the relationship between molecular structure and memory characteristics, two carbazole-based organic compounds (Cz-2Ph3F 6FDA and Cz-2TPA 6FDA) with different ratios of electron-donating and electron-withdrawing are designed and...

DNAzyme Sensor for the Detection of Ca2+ Using Resistive Pulse Sensing

DNAzymes are DNA oligonucleotides that can undergo a specific chemical reaction in the presence of a cofactor. Ribonucleases are a specific form of DNAzymes where a tertiary structure undergoes cleavage at a single ribonuclease site. The cleavage is highly specificity to co-factors, which makes them excellent sensor recognition elements. Monitoring the change in structure upon cleavage has given rise to many sensing strategies; here we present a simple and rapid method of following the reaction using resistive pulse sensors, RPS. To demonstrate this methodology, we present a sensor for Ca2+ ions in solution. A nanoparticle was functionalised with a Ca2+ DNAzyme, and it was possible to follow the cleavage and rearrangement of the DNA as the particles translocate the RPS. The binding of Ca2+ caused a conformation change in the DNAzyme, which was monitored as a change in translocation speed. A 30 min assay produced a linear response for Ca2+ between 1–9 μm, and extending the incubation time to 60 min allowed for a concentration as low as 0.3 μm. We demonstrate that the signal is specific to Ca2+ in the presence of other metal ions, and we can quantify Ca2+ in tap and pond water samples.

Acidic pH-Induced Conformational Changes in Chikungunya Virus Fusion Protein E1: a Spring-Twisted Region in the Domain I-III Linker Acts as a Hinge Point for Swiveling Motion of Domains

ABSTRACT Chikungunya virus (CHIKV), a mosquito-transmitted alphavirus, enters a cell through endocytosis, followed by viral and cell membrane fusion. The fusion protein, E1, undergoes an acid pH-induced pre- to postfusion conformation change during membrane fusion. As part of the conformation change, E1 dissociates from the receptor-binding protein, E2, and swivels its domains I and II over domain III to form an extended intermediate and then eventually to form a postfusion hairpin homotrimer. In this study, we tested if the domain I-III linker acts as a “hinge” for the swiveling motion of E1 domains. We found a conserved spring-twisted structure in the linker, stabilized by a salt bridge between a conserved arginine-aspartic acid pair, as a “hinge point” for domain swiveling. Molecular dynamics (MD) simulation of the CHIKV E1 or E2-E1 structure predicted that the spring-twisted region untwists at pH 5.5. Corroborating the prediction, introduction of a “cystine staple” at the hinge point, replacing the conserved arginine-aspartic acid pair with cysteine residues, resulted in loss of fusion activity of E1. MD simulation also predicted domain I-III swiveling at acidic pH. We tested if breaking the His 331-Lys 16 H bond between domains I and III, seen only in the prefusion conformation, is important for domain swiveling. When domains I and III are “stapled” by introducing a disulfide bond in between, E1 showed loss of fusion activity, implying that domain I and III dissociation is a critical acid pH-induced step in membrane fusion. However, replacement of His 331 with an acidic residue did not affect the pH threshold for fusion, suggesting His 331 is not an acid-sensing residue. IMPORTANCE Aedes mosquito-transmitted viruses such as the Zika, dengue, and chikungunya viruses have spread globally. CHIKV, similar to many other enveloped viruses, enters cells in sequential steps: step 1 involves receptor binding followed by endocytosis, and step 2 involves viral-cell membrane fusion in the endocytic vesicle. The viral envelope surface protein, E1, performs membrane fusion. E1 is triggered to undergo conformational changes by acidic pH of the maturing endosome. Different domains of E1 rearrange during the pre- to postfusion conformation change. Using in silico analysis of the E1 structure and different biochemical experiments, we explained a structural mechanism of key conformational changes in E1 triggered by acidic pH. We noted two important structural changes in E1 at acidic pH. In the first, a spring-twisted region in a loop connecting two domains (I and III) untwists, bringing a swiveling motion of domains on each other. In the second, breaking of interactions between domains I and III and domain separation are required for membrane fusion. This knowledge will help devise new therapeutic strategies to block conformation changes in E1 and thus viral entry.