Lineage structure of the human antibody repertoire in response to influenza vaccination

The adaptive immune system produces a large and diverse set of antibodies,each with an individual evolutionary and clonal history.This so called"antibody repertoire"protects each individual against insults such as infection and cancer,and responds to vaccination with B cell proliferation in response to the antigenic stimulation.Hybridomas and antigen-specific FACSbased analysis have given us much insight on how the immune system generates the complex and diverse immune response required to protect the body from the wide variety of potential pathogens.However,these methods have not been sufficient to make global and unbiased characterizations of the clonal structure of the immune system of a particular individual。

Osteogenesis imperfecta mutations in plastin 3 lead to impaired calcium regulation of actin bundling

Mutations in actin-bundling protein plastin 3(PLS3)emerged as a cause of congenital osteoporosis,but neither the role of PLS3 in bone development nor the mechanisms underlying PLS3-dependent osteoporosis are understood.Of the over 20 identified osteoporosis-linked PLS3 mutations,we investigated all five that are expected to produce full-length protein.One of the mutations distorted an actin-binding loop in the second actin-binding domain of PLS3 and abolished F-actin bundling as revealed by cryo-EM reconstruction and protein interaction assays.Surprisingly,the remaining four mutants fully retained F-actin bundling ability.However,they displayed defects in Ca2+sensitivity:two of the mutants lost the ability to be inhibited by Ca2+;while the other two became hypersensitive to Ca2a.Each group of the mutants with similar biochemical properties showed highly characteristic cellular behavior.Wild-type PLS3 was distributed between lamellipodia and focal adhesions.In striking contrast,the Ca2+-hyposensitive mutants were not found at the leading edge but localized exclusively at focal adhesions/stress fibers,which displayed reinforced morphology.Consistently,the Ca2+-hypersensitive PLS3 mutants were restricted to lamellipodia,while chelation of Ca2+caused their redistribution to focal adhesions.Finally,the bundling-deficient mutant failed to co-localize with any F-actin structures in cells despite a preserved F-actin binding through a non-mutation-bearing actin-binding domain.Our findings revealed that severe osteoporosis can be caused by a mutational disruption of the Ca2+-controlled PLS3’s cycling between adhesion complexes and the leading edge.Integration of the structural,biochemical,and cell biology insights enabled us to propose a molecular mechanism of plastin activity regulation by Ca2+.

McSNAC:A software to approximate first-order signaling networks from mass cytometry data

Background:Mass cytometry(CyTOF)gives unprecedented opportunity to simultaneously measure up to 40 proteins in single cells,with a theoretical potential to reach 100 proteins.This high-dimensional single-cell information can be very useful in dissecting mechanisms of cellular activity.In particular,measuring abundances of signaling proteins like phospho-proteins can provide detailed information on the dynamics of single-cell signaling processes.However,computational analysis is required to reconstruct such networks with a mechanistic model.Methods:We propose our Mass cytometry Signaling Network Analysis Code(McSNAC),a new software capable of reconstructing signaling networks and estimating their kinetic parameters from CyTOF data.McSNAC approximates signaling networks as a network of first-order reactions between proteins.This assumption often breaks down as signaling reactions can involve binding and unbinding,enzymatic reactions,and other nonlinear constructions.Furthermore,McSNAC may be limited to approximating indirect interactions between protein species,as cytometry experiments are only able to assay a small fraction of protein species involved in signaling.Results:We carry out a series of in silico experiments here to show(1)McSNAC is capable of accurately estimating the ground-truth model in a scalable manner when given data originating from a first-order system;(2)McSNAC is capable of qualitatively predicting outcomes to perturbations of species abundances in simple second-order reaction models and in a complex in silico nonlinear signaling network in which some proteins are unmeasured.Conclusions:These findings demonstrate that McSNAC can be a valuable screening tool for generating models of signaling networks from time-stamped CyTOF data.

A nanotherapeutic strategy to target drug-tolerant cells and overcome EGFR tyrosine kinase inhibitor resistance in lung cancer

Dear Editor,For patientswith epidermal growth factor receptor(EGFR)mutant non-small cell lung cancer(NSCLC),EGFR tyrosine kinase inhibitors(TKIs)are used as the first-line treatment[1,2].Despite initial therapeutic responses,patients invariably experience disease progression due to acquired drug resistance[3].Resistance arises,in part,because a subset of cancer cells undergoes epithelial-mesenchymal transition(EMT)and remains viable despite exposure to EGFR TKI concentrations that eliminate the bulk population[4].The surviving cells can be re-sensitized to treatment by prolonged culture in the absence of EGFR TKIs,indicating a transient.

Low-cost,simple,and scalable self-assembly of DNA origami nanostructures

Despite demonstrating exciting potential for applications such as drug delivery and biosensing,the development of nanodevices for practical applications and broader use in research and education are still hindered by the time,effort,and cost associated with DNA origami fabrication.Simple and robust methods to perform and scale the DNA origami self-assembly process are critical to facilitate broader use and translation to industrial or clinical applications.We report a simple approach to fold DNA origami nanostructures that is fast,robust,and scalable.We demonstrate fabrication at scales approximately 100-1,500-fold higher than typical scales.We further demonstrate an approach we termed low-cost efficient annealing (LEAN) self-assembly involving initial heating at 65 ℃ for 10 min,then annealing at 51 ℃ for 2 h,followed by brief quenching at 4 ℃ that leads to effective assembly of a range of DNA origami structures tested.In contrast to other methods for scaling DNA origami assembly,this approach can be carried out using cheap and widely available equipment (e.g.,hot plates,water baths,and laboratory burners) and uses standard recipes and materials so is readily applied to any existing or new DNA origami designs.We envision these methods can facilitate device development for commercial applications and facilitate broader use of DNA origami in research and education.

Ultrafast photonic PCR

Nucleic acid amplification and quantification via polymerase chain reaction(PCR)is one of the most sensitive and powerful tools for clinical laboratories,precision medicine,personalized medicine,agricultural science,forensic science and environmental science.Ultrafast multiplex PCR,characterized by low power consumption,compact size and simple operation,is ideal for timely diagnosis at the point-of-care(POC).Although several fast/ultrafast PCR methods have been proposed,the use of a simple and robust PCR thermal cycler remains challenging for POC testing.Here,we present an ultrafast photonic PCR method using plasmonic photothermal light-to-heat conversion via photon–electron–phonon coupling.We demonstrate an efficient photonic heat converter using a thin gold(Au)film due to its plasmon-assisted high optical absorption(approximately 65%at 450 nm,the peak wavelength of heat source light-emitting diodes(LEDs)).The plasmon-excited Au film is capable of rapidly heating the surrounding solution to over 150℃ within 3 min.Using this method,ultrafast thermal cycling(30 cycles;heating and cooling rate of 12.7960.93℃ s^(-1) and 6.660.29℃ s^(-1),respectively)from 55℃(temperature of annealing)to 95℃(temperature of denaturation)is accomplished within 5 min.Using photonic PCR thermal cycles,we demonstrate here successful nucleic acid(λ-DNA)amplification.Our simple,robust and low cost approach to ultrafast PCR using an efficient photonic-based heating procedure could be generally integrated into a variety of devices or procedures,including on-chip thermal lysis and heating for isothermal amplifications.

Plasmonic bacteria on a nanoporous mirror via hydrodynamic trapping for rapid identification of waterborne pathogens

A rapid,precise method for identifying waterborne pathogens is critically needed for effective disinfection and better treatment.However,conventional methods,such as culture-based counting,generally suffer from slow detection times and low sensitivities.Here,we developed a rapid detection method for tracing waterborne pathogens by an innovative optofluidic platform,a plasmonic bacteria on a nanoporous mirror,that allows effective hydrodynamic cell trapping,enrichment of pathogens,and optical signal amplifications.We designed and simulated the integrated optofluidic platform to maximize the enrichment of the bacteria and to align bacteria on the nanopores and plasmonic mirror via hydrodynamic cell trapping.Gold nanoparticles are self-assembled to form antenna arrays on the surface of bacteria,such as Escherichia coli and Pseudomonas aeruginosa,by replacing citrate with hydroxylamine hydrochloride in order to amplify the signal of the plasmonic optical array.Owing to the synergistic contributions of focused light via the nanopore geometry,self-assembled nanoplasmonic optical antennas on the surface of bacteria,and plasmonic mirror,we obtain a sensitivity of detecting E.coli as low as 102 cells/ml via surface-enhanced Raman spectroscopy.We believe that our label-free strategy via an integrated optofluidic platform will pave the way for the rapid,precise identification of various pathogens.

Bioinspired optical antennas: gold plant viruses

The ability to capture the chemical signatures of biomolecules(i.e.,electron-transfer dynamics)in living cells will provide an entirely new perspective on biology and medicine.This can be accomplished using nanoscale optical antennas that can collect,resonate and focus light from outside the cell and emit molecular spectra.Here,we describe biologically inspired nanoscale optical antennas that utilize the unique topologies of plant viruses(and thus,are called gold plant viruses)for molecular fingerprint detection.Our electromagnetic calculations for these gold viruses indicate that capsid morphologies permit high amplification of optical scattering energy compared to a smooth nanosphere.From experimental measurements of various gold viruses based on four different plant viruses,we observe highly enhanced optical cross-sections and the modulation of the resonance wavelength depending on the viral morphology.Additionally,in label-free molecular imaging,we successfully obtain higher sensitivity(by a factor of up to 10^(6))than can be achieved using similar-sized nanospheres.By virtue of the inherent functionalities of capsids and the plasmonic characteristics of the gold layer,a gold virus-based antenna will enable cellular targeting,imaging and drug delivery.

Did the Nationalist Government Manipulate the Chinese Bond Market？ A Quantitative Perspective on Short-Term Price Fluctuations of Domestic Government Bonds, 1932-1934

Based on a newly constructed set of data, this paper offers a quantitative perspective on the Nationalist Government＇s relations with China＇s domestic bond markets during the period 1932-34. For all the recent revisionist scholarship on the achievements of Nationalist state-building, the perception of the Nationalist elite as corrupt is still widely accepted. In order to demonstrate the empirical potential of quantitative financial history, this paper tests one particular assertion： that members of the Nationalist elite manipulated the issue price of domestic government bonds in order to enrich themselves and their associates. We test this by calculating two price data correlations： that of a first sample of government bonds, all of them issued before 1932, and that of a second sample of government bonds, which includes bonds issued during the period under review. The price fluctuations of the first sample are correlated with each other to a much higher degree than those of the second sample. This indicates that the prices of bonds in the first sample were reacting similarly to the same range of influences, while the bonds issued during the period under review and included in the second sample were displaying individual price fluctuations. One possible explanation for this is that members of the Nationalist elite enriched themselves or their associates by issuing domestic government bonds at artificially low prices. In sum, the article illustrates both the potential and the limitations of quantitative history： it allows us to test and dismiss a precisely formulated hypothesis about Nationalist corruption, but it is only one possible way in which statistical analysis can be applied and does not cover the wholeDid the Nationalist Government Manipulate the Chinese Bond Market？ realm of state practices