A digital assay is one in which the sample is partitioned into many containers such that each partition contains a discrete number of biological entities (0, 1, 2, 3, …). A powerful technique in the ...biologist’s toolkit, digital assays bring a new level of precision in quantifying nucleic acids, measuring proteins and their enzymatic activity, and probing single-cell genotype and phenotype. Where part I of this review focused on the fundamentals of partitioning and digital PCR, part II turns its attention to digital protein and cell assays. Digital enzyme assays measure the kinetics of single proteins with enzymatic activity. Digital enzyme-linked immunoassays (ELISAs) quantify antigenic proteins with 2 to 3 log lower detection limit than conventional ELISA, making them well suited for low-abundance biomarkers. Digital cell assays probe single-cell genotype and phenotype, including gene expression, intracellular and surface proteins, metabolic activity, cytotoxicity, and transcriptomes (scRNA-seq). These methods exploit partitioning to 1) isolate single cells or proteins, 2) detect their activity via enzymatic amplification, and 3) tag them individually by coencapsulating them with molecular barcodes. When scaled, digital assays reveal stochastic differences between proteins or cells within a population, a key to understanding biological heterogeneity. This review is intended to give a broad perspective to scientists interested in adopting digital assays into their workflows.
デジタルアッセイとはサンプルを多数の微細なコンテナに分配し、各パーティションに個々の数（0、1、2、3…）の生物学的実体が含まれるようにする方法である。生物学者用ツールキットの有力な手段であるデジタルアッセイは、核酸の定量、種々のタンパク質とそれらの酵素活性の測定、および単細胞由来の遺伝子型および表現型の探索の精度を新たなレベルに引き上げる。本レビューのパート1ではパーティショニングとデジタルPCRの基本に重点を置いているが、パート2ではタンパク質と細胞のデジタルアッセイに注目する。酵素デジタルアッセイは酵素活性により単一タンパク質の動態を定量化し測定する。デジタル酵素結合免疫測定法（デジタルELISA法）はタンパク質の定量において従来のELISA法より検出下限が2～3log低いためするため、低含量のバイオマーカーに適切である。細胞デジタルアッセイは単細胞由来の遺伝子型と表現型について、例えば遺伝子発現、細胞間および細胞表面のタンパク質、代謝活性、細胞傷害性、およびトランスクリプトーム（scRNA-SEQ）などを探索する。これらの方法はパーティショニングを活用して、酵素増幅を通じて分子を検出し、単細胞活性を隔離し、単細胞のトレーサビリティを確保する。スケールを調整するとデジタルアッセイは、ある母集団内のタンパク質または細胞間の推計学的差、すなわち生物学的不均一性を理解する鍵となる推計学的差を明らかにする。本レビューの目的は、デジタルアッセイを自身のワークフローに採用することに関心のある科学者に、幅広い展望を示すことである。
数字测定表示将样本分别装入众多容器中，以便每个分区包含不同数量的生物实体（0、1、2、3……）。作为生物学家工具包中一项功能出色的技术，数字测定可以全面提升核酸定量、蛋白质及其酶活性测量以及单细胞基因型和表现型检测的精度。本文第一部分重点介绍了分区和数字PCR的基础知识，第二部分将关注数字蛋白质和细胞测定。数字酶测定可以定量和测量单一蛋白质与酶活性的动力学。相比传统ELISA方法，数字酶联免疫测定（ELISA）可以定量具有2-3个更低检测限制的蛋白质，非常适合低丰度生物标志物。数字细胞测定可以检测单细胞基因型和表现型，包括基因表达、细胞内和表面蛋白质、代谢活动、细胞毒性和转录物组（scRNA-SEQ）。这些方法能够探索分区以并通过酶扩增检测分子、隔离单细胞活动并提供单细胞溯源性的可能。分区后，数字测定可以显示群体中蛋白质或细胞的随机差异，这是理解生物异质性的关键。本文旨在为有意引入数字测定的科学家提供全面的介绍。
数字测定表示将样本分别装入众多容器中，以便每个分区包含不同数量的生物实体（0、1、2、3……）。作为生物学家工具包中一项功能出色的技术，数字测定可以全面提升核酸定量、蛋白质及其酶活性测量以及单细胞基因型和表现型检测的精度。本文第一部分重点介绍了分区和数字PCR的基础知识，第二部分将关注数字蛋白质和细胞测定。数字酶测定可以定量和测量单一蛋白质与酶活性的动力学。相比传统ELISA方法，数字酶联免疫测定（ELISA）可以定量具有2-3个更低检测限制的蛋白质，非常适合低丰度生物标志物。数字细胞测定可以检测单细胞基因型和表现型，包括基因表达、细胞内和表面蛋白质、代谢活动、细胞毒性和转录物组（scRNA-SEQ）。这些方法能够探索分区以并通过酶扩增检测分子、隔离单细胞活动并提供单细胞溯源性的可能。分区后，数字测定可以显示群体中蛋白质或细胞的随机差异，这是理解生物异质性的关键。本文旨在为有意引入数字测定的科学家提供全面的介绍。
ABSTRACT
This paper presents the results of a set of radiative hydrodynamic simulations of convection in the near-surface regions of a rapidly rotating star. The simulations use microphysics ...consistent with stellar models, and include the effects of realistic convection and radiative transfer. We find that the overall effect of rotation is to reduce the strength of turbulence. The combination of rotation and radiative cooling creates a zonal velocity profile in which the motion of fluid parcels near the surface is independent of rotation. Their motion is controlled by the strong up and down flows generated by radiative cooling. The fluid parcels in the deeper layers, on the other hand, are controlled by rotation.
Hypoxia plays a vital role in tumor microenvironment by allowing development and maintenance of cancer cells thereby led to major hindrance for effective anticancer therapy and main reason for ...failure of most anticancer drugs. We herein investigated the therapeutic efficacy and molecular mechanism of action of aqua-(2-formylbenzoato) triphenyltin (IV) compound (OTC) in MDA-MB-231 cell line. Cobalt chloride induced hypoxic MDA-MB-231 cells treated with OTC were used to access cytotoxicity, ROS, cellular apoptosis, and cell cycle progression. Further, expression of HIF-1α and VEGF, as well as apoptotic proteins like p53, Bax, Bcl-2 and caspase 3 were assessed. The findings indicated that OTC is more effective towards CoCl2 induced hypoxic cells when compared to normoxic cells and the results are far superior to doxorubicin. Additionally, our study revealed that OTC facilitates more ROS production induced cell cycle arrest and promote apoptosis. Furthermore, OTC significantly down regulates the expression of Hif-1α, VEGF and Bcl-2 in hypoxic condition and elevates the level of p53, Bax, cytochrome-C and Caspase 3. Our in vitro studies demonstrated that OTC showed better efficacy than doxorubicin, corroborating that OTC could be a promising compound for hypoxic cancer that also display multi drug resistant.
•Newly synthesized OTC suppresses the growth of hypoxia induced breast cancer cells.•OTC induces cell cycle delay and promote apoptosis in p53 dependent manner.•In-silico analysis confirms strong interaction with DNA and p53 and Hif-1α protein.
ABSTRACT
The evolution of low-mass stars into red giants is still poorly understood. During this evolution the core of the star contracts and, simultaneously, the envelope expands – a process known ...as the ‘mirror’. Additionally, there is a short phase where the trend for increasing luminosity is reversed. This is known as the red giant branch bump. We explore the underlying physical reasons for these two phenomena by considering the specific entropy distribution in the star and its temporal changes. We find that between the luminosity maximum and luminosity minimum of the bump there is no mirror present and the star is fully contracting. The contraction is halted and the star regains its mirror when the hydrogen-burning shell reaches the mean molecular weight discontinuity. This marks the luminosity minimum of the bump.
Main-sequence, solar-like stars (M 1.5 M ) have outer convective envelopes that are sufficiently thick to affect significantly their overall structure. The radii of these stars, in particular, are ...sensitive to the details of inefficient, superadiabatic convection occurring in their outermost layers. The standard treatment of convection in stellar evolution models, based on the mixing-length theory (MLT), provides only a very approximate description of convection in the superadiabatic regime. Moreover, it contains a free parameter, MLT, whose standard calibration is based on the Sun and is routinely applied to other stars, ignoring the differences in their global parameters (e.g., effective temperature, gravity, chemical composition) and previous evolutionary history. In this paper, we present a calibration of MLT based on 3D radiation hydrodynamics (RHD) simulations of convection. The value of MLT is adjusted to match the specific entropy in the deep, adiabatic layers of the convective envelope to the corresponding value obtained from the 3D RHD simulations, as a function of the position of the star in the plane and its chemical composition. We have constructed a model of the present-day Sun using such entropy-based calibration. We find that its past luminosity evolution is not affected by the entropy calibration. The predicted solar radius, however, exceeds that of the standard model during the past several billion years, resulting in a lower surface temperature. This illustrative calculation also demonstrates the viability of the entropy approach for calibrating the radii of other late-type stars.
Pro-ligand 5-(E)-2-(3-pyridyl)-1-diazenyl-2-hydroxybenzoic acid, H′HLmeta, was employed for the synthesis of four organotin(IV) complexes, using suitable tri- and diorganotin (IV) precursors, ...nBu3Sn(HLmeta) n (1), Bz3Sn(HLmeta) n ·C6H5CH3 (2), Ph3Sn(HLmeta)4·C6H5CH3 (3), and {nBu2Sn(Lmeta)2} n ·2nDMSO (4). The coordination behavior of compounds 1–3 in solution was judged from the results of the 119Sn NMR spectroscopic characterization, while the 119Sn MAS NMR technique was utilized to probe 4, owing to its low-solubility issue. The solid-state structures of 1–4 were determined from single-crystal X-ray diffraction data. The structural analysis revealed that by changing the Sn-R substituents, the molecular coordination geometries and supramolecular structural motifs in the resulting compounds are widely affected. However, one common feature in the crystal structures of these compounds is a strong tendency for the terminal pyridyl nitrogen to bind with the tin atom of an adjacent complex molecule, which influences the ligand bonding interactions and leads to either macrocycle or polymer formation. In compounds 1–3, the triorganotin moieties are embedded in trigonal–bipyramidal coordination polyhedra arising from the ligand in the monodeprotonated salicylate form, HLmeta−, by complexation through the carboxylate group, resulting in 1D coordination polymers with a zigzag-type topology for compounds 1 and 2, and a tetranuclear 44-membered macrocyclic ring structure in the case of 3. The different outcome is a result of the all anti-conformation of the HLmeta− ligands in compounds 1 and 2, compared with alternating syn- and anti-conformation of the four ligands in 3, and is without doubt related to the variation of the triorganotin functionality. In compound 4, the tin atoms coordinate to the salicylate group of dianionic Lmeta2– by chelate ring formation with both the carboxylate and phenolate groups. The combination of syn-conformation of the ligand and secondary building block formation through 4-membered Sn2O2 rings gives rise to 1D tapes containing 22-membered tetranuclear macrocycles. The case study reported herein showed that heteroditopic pyridyl-carboxylate ligands derived from salicylic acid by diazonium coupling are providing an interesting ligand family for complexation and self-assembly studies with a large number of single main group and transition ions and preformed di- or oligonuclear tectons.
Rotation is expected to have an important influence on the structure and the evolution of stars. However, the mechanisms of angular momentum transport in stars remain theoretically uncertain and very ...complex to take into account in stellar models. To achieve a better understanding of these processes, we desperately need observational constraints on the internal rotation of stars, which until very recently was restricted to the Sun. In this paper, we report the detection of mixed modes-i.e., modes that behave both as g modes in the core and as p modes in the envelope-in the spectrum of the early red giant KIC 7341231, which was observed during one year with the Kepler spacecraft. By performing an analysis of the oscillation spectrum of the star, we show that its non-radial modes are clearly split by stellar rotation and we are able to determine precisely the rotational splittings of 18 modes. We then find a stellar model that reproduces very well the observed atmospheric and seismic properties of the star. We use this model to perform inversions of the internal rotation profile of the star, which enables us to show that the core of the star is rotating at least five times faster than the envelope. This will shed new light on the processes of transport of angular momentum in stars. In particular, this result can be used to place constraints on the angular momentum coupling between the core and the envelope of early red giants, which could help us discriminate between the theories that have been proposed over the last few decades.
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