The integrity of RNA molecules is of paramount importance for experiments that try to reflect the snapshot of gene expression at the moment of RNA extraction. Until recently, there has been no reliable standard for estimating the integrity of RNA samples and the ratio of 28S:18S ribosomal RNA, the common measure for this purpose, has been shown to be inconsistent. The advent of microcapillary electrophoretic RNA separation provides the basis for an automated high-throughput approach, in order to estimate the integrity of RNA samples in an unambiguous way. A method is introduced that automatically selects features from signal measurements and constructs regression models based on a Bayesian learning technique. Feature spaces of different dimensionality are compared in the Bayesian framework, which allows selecting a final feature combination corresponding to models with high posterior probability. This approach is applied to a large collection of electrophoretic RNA measurements recorded with an Agilent 2100 bioanalyzer to extract an algorithm that describes RNA integrity. The resulting algorithm is a user-independent, automated and reliable procedure for standardization of RNA quality control that allows the calculation of an RNA integrity number (RIN). Our results show the importance of taking characteristics of several regions of the recorded electropherogram into account in order to get a robust and reliable prediction of RNA integrity, especially if compared to traditional methods.

/pdf/the-rin-an-rna-integrity-number-for-assigning-integrity-2h6tnunr7z.pdf

The RIN: an RNA integrity number for assigning integrity values to RNA measurements

After having reviewed some aspects of microfluidic system preparation in the first part (1), in this second part of the review we will cover a number of standard operations (namely: sample preparation, sample injection, sample manipulation, reaction, separation, and detection) as well as some biological applications of micro total analysis systems (namely: cell culture, polymerase chain reaction, DNA separation, DNA sequencing, and clinical diagnostics). As previously, we will include papers issued from different scientific journals as well as useful abstracts from three conference proceedings: MEMS, Transducers, and μTAS. In this second part, we do not include the period covered by the history section (1975-1997) from part 1 but try to cover the relevant examples of the literature published between January 1998 and March 2002. We briefly describe articles that struck us as needing special attention, while more “standard” papers are dutifully reported in groups of interest. An article might be included in more than one section, depending on the ideas developed in it.

Micro total analysis systems. 2. Analytical standard operations and applications.

https://www.gene-quantification.de/fleige-pfaffl-rin-2006.pdf

RNA integrity and the effect on the real-time qRT-PCR performance

Integrated microfluidic devices

Haplotypes have gained increasing attention in the mapping of complex-disease genes, because of the abundance of single-nucleotide polymorphisms (SNPs) and the limited power of conventional single-locus analyses. It has been shown that haplotype-inference methods such as Clark's algorithm, the expectation-maximization algorithm, and a coalescence-based iterative-sampling algorithm are fairly effective and economical alternatives to molecular-haplotyping methods. To contend with some weaknesses of the existing algorithms, we propose a new Monte Carlo approach. In particular, we first partition the whole haplotype into smaller segments. Then, we use the Gibbs sampler both to construct the partial haplotypes of each segment and to assemble all the segments together. Our algorithm can accurately and rapidly infer haplotypes for a large number of linked SNPs. By using a wide variety of real and simulated data sets, we demonstrate the advantages of our Bayesian algorithm, and we show that it is robust to the violation of Hardy-Weinberg equilibrium, to the presence of missing data, and to occurrences of recombination hotspots.

/pdf/bayesian-haplotype-inference-for-multiple-linked-single-1d61fjors4.pdf

Bayesian Haplotype Inference for Multiple Linked Single-Nucleotide Polymorphisms

Microfabrication technology was used to develop a system consisting of disposable glass chips containing etched channels, reagents including polymer matrix and size standards, computer-controlled instrumentation for performing electrophoretic separations and fluorescence detection of double-stranded DNA, and software for automated data analysis. System performance was validated for separation and quantitation reproducibility using samples varying in amount and size of DNA fragments, buffer composition, and salt concentrations. Several applications of the microfluidic system for DNA analysis have been demonstrated, such as of polymerase chain reaction (PCR) products, sizing of plasmid digests, and detection of point mutations by restriction fragment length polymorphism (RFLP) mapping.

A microfluidic system for high-speed reproducible DNA sizing and quantitation

An electrophoretic technique is provided for moving a plurality of chemicals into distinct zones for immobilization on a solid surface. The technique includes introducing a first electrolyte and a second electrolyte into a channel, and interposing between the first and second electrolytes at least one solution containing a plurality of chemicals. Under a given electric field, the first electrolyte has anions with higher effective mobility than the chemicals and the second electrolyte has anions with lower effective mobility than the chemicals. When an electrical potential is applied across the length of the channel the plurality of chemicals in the solution are moved into spatial zones. The chemicals in the zones can then be bound to the interior surface of the channel. Chemicals so bound to the wall surface can be used to build very small structures such as arrays and electrical conducting structures.

Method of binding a plurality of chemicals on a substrate by electrophoretic self-assembly

The challenge of analyzing biological samples is driving diverse disciplines toward a common analytical platform.

Integrated genomic/proteomic analysis.

Analysis of recombinant adenoviruses using an integrated microfluidic chip-based system.

A method is provided for the separation of nucleic acid samples. The method includes: providing a test mixture of a plurality of nucleic acid samples, wherein each sample is labeled with a spectrally detectable tag; applying the test mixture to a reversed phase solid support; eluting the mixture under partially denaturing conditions; and detecting spectrally resolved signals produced by the nucleic acid samples labeled with the detectable tags.

Karen Hahnenberger

Papers

A microfluidic system for high-speed reproducible DNA sizing and quantitation

Method of binding a plurality of chemicals on a substrate by electrophoretic self-assembly

Integrated genomic/proteomic analysis.

Analysis of recombinant adenoviruses using an integrated microfluidic chip-based system.

Multiplexing methods for identifying nucleic acids using denaturing liquid chromatography