Microfluidic Technologies for Synthetic Biology

Microfluidic technologies have shown powerful abilities for reducing cost, time, and labor, and at the same time, for increasing accuracy, throughput, and performance in the analysis of biological and biochemical samples compared with the conventional, macroscale instruments. Synthetic biology is an emerging field of biology and has drawn much attraction due to its potential to create novel, functional biological parts and systems for special purposes. Since it is believed that the development of synthetic biology can be accelerated through the use of microfluidic technology, in this review work we focus our discussion on the latest microfluidic technologies that can provide unprecedented means in synthetic biology for dynamic profiling of gene expression/regulation with high resolution, highly sensitive on-chip and off-chip detection of metabolites, and whole-cell analysis

Morpho-transduction du gène twist lors de l'invagination du mésoderme dans l'embryon de Drosophila melanogaster

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF

Morpho-transduction du gène twist lors de l'invagination du mésoderme dans l'embryon de Drosophila melanogaster

PARIS7-Bibliothèque centrale (751132105) / SudocSudocFranceF

dPCR: A Technology Review

Digital Polymerase Chain Reaction (dPCR) is a novel method for the absolute quantification of target nucleic acids. Quantification by dPCR hinges on the fact that the random distribution of molecules in many partitions follows a Poisson distribution. Each partition acts as an individual PCR microreactor and partitions containing amplified target sequences are detected by fluorescence. The proportion of PCR-positive partitions suffices to determine the concentration of the target sequence without a need for calibration. Advances in microfluidics enabled the current revolution of digital quantification by providing efficient partitioning methods. In this review, we compare the fundamental concepts behind the quantification of nucleic acids by dPCR and quantitative real-time PCR (qPCR). We detail the underlying statistics of dPCR and explain how it defines its precision and performance metrics. We review the different microfluidic digital PCR formats, present their underlying physical principles, and analyze the technological evolution of dPCR platforms. We present the novel multiplexing strategies enabled by dPCR and examine how isothermal amplification could be an alternative to PCR in digital assays. Finally, we determine whether the theoretical advantages of dPCR over qPCR hold true by perusing studies that directly compare assays implemented with both methods

Precise pooling and dispensing of microfluidic droplets towards micro- to macro-world interfacing

Methane hydrate is a fascinating physical occurrence of methane and water in solid-state. Methane Hydrates have been under investigation for several decades due to its importance in energy and environment, and its various applications in physical sciences and technologies. I developed models in the laboratory to gain insight into (i) secondary hydrate formation in the porous medium, which involves crystallization with hysteresis, and (ii) multi-phase (gas-water) occurrence and flow in the presence of hydrates in the porous medium. In the first part, methane hydrate is formed in a sand pack that undergoes cooling-heating cycles over a range of temperatures. Five cycles are designed so that hysteresis can be observed in the sand pack. Each cycle has a different melting temperature which, leads to varying intensity of temperature relaxation effect on the hysteresis. Evidence of hysteresis is observed in three separate temperature readings of thermocouples. The formation of hydrates is dependent on the thermal cooling rate of the sand pack, and the melting temperature of the previous cycle. A temperature increase is observed in the whole system, and this increase is driven by temperature peaks indicating significant hydrate formation near the thermocouples. These peaks have substantial effects on the entire system. By comparing each cycle’s temperature peaks, hysteresis is observed at the temperature readings of the short thermocouple. The same hysteresis pattern follows for the location of the temperature peaks. A new mechanistic model, following the residual cage theory, is proposed for the prediction of secondary hydrate formation time as a function of the melting temperature. In the second part, methane hydrate is formed in the sand pack in a transparent x-ray vessel. The gas relative permeability in the presence of methane hydrate is measured using two different steady-state flow experiments: single-phase (gas) flow, multi-phase (water-gas) simultaneous flow. Water and gas co-flow experiments cause issues that complicate the results, while the single-phase gas flow method gives good results. Therefore, in measuring relative permeability in the presence of gas hydrates, single-phase gas flow measurements are recommended. A new empirical equation is given correlating the relative permeability to hydrate saturation

A Droplet Microfluidics Based Platform for Mining Metagenomic Libraries for Natural Compounds

Historically, microbes from the environment have been a reliable source for novel bio-active compounds. Cloning and expression of metagenomic DNA in heterologous strains of bacteria has broadened the range of potential compounds accessible. However, such metagenomic libraries have been under-exploited for applications in mammalian cells because of a lack of integrated methods. We present an innovative platform to systematically mine natural resources for pro-apoptotic compounds that relies on the combination of bacterial delivery and droplet microfluidics. Using the violacein operon from C. violaceum as a model, we demonstrate that E. coli modified to be invasive can serve as an efficient delivery vehicle of natural compounds. This approach permits the seamless screening of metagenomic libraries with mammalian cell assays and alleviates the need for laborious extraction of natural compounds. In addition, we leverage the unique properties of droplet microfluidics to amplify bacterial clones and perform clonal screening at high-throughput in place of one-compound-per-well assays in multi-well format. We also use droplet microfluidics to establish a cell aggregate strategy that overcomes the issue of background apoptosis. Altogether, this work forms the foundation of a versatile platform to efficiently mine the metagenome for compounds with therapeutic potential

A droplet microfluidics based platform for mining metagenomic libraries for natural compounds

Historically, microbes from the environment have been a reliable source for novel bio-active compounds. Cloning and expression of metagenomic DNA in heterologous strains of bacteria has broadened the range of potential compounds accessible. However, such metagenomic libraries have been under-exploited for applications in mammalian cells because of a lack of integrated methods. We present an innovative platform to systematically mine natural resources for pro-apoptotic compounds that relies on the combination of bacterial delivery and droplet microfluidics. Using the violacein operon from C. violaceum as a model, we demonstrate that E. coli modified to be invasive can serve as an efficient delivery vehicle of natural compounds. This approach permits the seamless screening of metagenomic libraries with mammalian cell assays and alleviates the need for laborious extraction of natural compounds. In addition, we leverage the unique properties of droplet microfluidics to amplify bacterial clones and perform clonal screening at high-throughput in place of one-compound-per-well assays in multi-well format. We also use droplet microfluidics to establish a cell aggregate strategy that overcomes the issue of background apoptosis. Altogether, this work forms the foundation of a versatile platform to efficiently mine the metagenome for compounds with therapeutic potential. ©2017 Keywords: metagenomic screening; droplet microfluidics; high-throughput screening; natural compoundNational Institute of Health (grat no. NCI-1R43GM95227

Adult T-Cell Leukemia/Lymphoma in a Caucasian Patient After Sexual Transmission of Human T-Cell Lymphotropic Virus Type 1.

International audienceAdult T-cell leukemia/lymphoma (ATLL), a T-cell neoplasm caused by human T-cell lymphotropic virus type 1 (HTLV-1), develops in the majority of cases in individuals who were infected with HTLV-1 as young children, by their mother during prolonged breastfeeding. We report the case of a Caucasian French man, whose parents were HTLV-1-seronegative and who developed ATLL after HTLV-1 sexual transmission by a Cameroonian woman. This hypothesis was corroborated by genotyping of the patient's virus, which revealed an HTLV-1B strain, found only in Central Africa, especially in Cameroon. Thus, ATLL may develop after HTLV-1 infection during adulthood, outside breastfeeding