Gel electrophoresis is a method for separation and analysis of biomacromolecules and their fragments, based on their size and charge. It is used in clinical chemistry to separate proteins by charge or size and in biochemistry and molecular biology to separate a mixed population of DNA and RNA fragments by length, to estimate the size of DNA and RNA fragments or to separate proteins by charge.
Molecular biology is a branch of biology that seeks to understand the molecular basis of biological activity in and between cells, including biomolecular synthesis, modification, mechanisms, and interactions.
The northern blot, or RNA blot, is a technique used in molecular biology research to study gene expression by detection of RNA in a sample.
In molecular biology, restriction fragment length polymorphism (RFLP) is a technique that exploits variations in homologous DNA sequences, known as polymorphisms, populations, or species or to pinpoint the locations of genes within a sequence. The term may refer to a polymorphism itself, as detected through the differing locations of restriction enzyme sites, or to a related laboratory technique by which such differences can be illustrated. In RFLP analysis, a DNA sample is digested into fragments by one or more restriction enzymes, and the resulting restriction fragments are then separated by gel electrophoresis according to their size.
Southern blot is a method used for detection and quantification of a specific DNA sequence in DNA samples. This method is used in molecular biology. Briefly, purified DNA from a biological sample is digested with restriction enzymes, and the resulting DNA fragments are separated by using an electric current to move them through a sieve-like gel or matrix, which allows smaller fragments to move faster than larger fragments. The DNA fragments are transferred out of the gel or matrix onto a solid membrane, which is then exposed to a DNA probe labeled with a radioactive, fluorescent, or chemical tag. The tag allows any DNA fragments containing complementary sequences with the DNA probe sequence to be visualized within the Southern blot.
Oligonucleotides are short DNA or RNA molecules, oligomers, that have a wide range of applications in genetic testing, research, and forensics. Commonly made in the laboratory by solid-phase chemical synthesis, these small fragments of nucleic acids can be manufactured as single-stranded molecules with any user-specified sequence, and so are vital for artificial gene synthesis, polymerase chain reaction (PCR), DNA sequencing, molecular cloning and as molecular probes. In nature, oligonucleotides are usually found as small RNA molecules that function in the regulation of gene expression, or are degradation intermediates derived from the breakdown of larger nucleic acid molecules.
Leroy "Lee" Edward Hood is an American biologist who has served on the faculties at the California Institute of Technology (Caltech) and the University of Washington. Hood has developed ground-breaking scientific instruments which made possible major advances in the biological sciences and the medical sciences. These include the first gas phase protein sequencer (1982), for determining the sequence of amino acids in a given protein; a DNA synthesizer (1983), to synthesize short sections of DNA; a peptide synthesizer (1984), to combine amino acids into longer peptides and short proteins; the first automated DNA sequencer (1986), to identify the order of nucleotides in DNA; ink-jet oligonucleotide technology for synthesizing DNA and nanostring technology for analyzing single molecules of DNA and RNA.
A blot, in molecular biology and genetics, is a method of transferring proteins, DNA or RNA onto a carrier. In many instances, this is done after a gel electrophoresis, transferring the molecules from the gel onto the blotting membrane, and other times adding the samples directly onto the membrane. After the blotting, the transferred proteins, DNA or RNA are then visualized by colorant staining, autoradiographic visualization of radiolabelled molecules, or specific labelling of some proteins or nucleic acids. The latter is done with antibodies or hybridization probes that bind only to some molecules of the blot and have an enzyme joined to them. After proper washing, this enzymatic activity is visualized by incubation with proper reactive, rendering either a colored deposit on the blot or a chemiluminescent reaction which is registered by photographic film.
Sanger sequencing is a method of DNA sequencing that involves electrophoresis and is based on the random incorporation of chain-terminating dideoxynucleotides by DNA polymerase during in vitro DNA replication. After first being developed by Frederick Sanger and colleagues in 1977, it became the most widely used sequencing method for approximately 40 years. It was first commercialized by Applied Biosystems in 1986. More recently, higher volume Sanger sequencing has been replaced by next generation sequencing methods, especially for large-scale, automated genome analyses. However, the Sanger method remains in wide use for smaller-scale projects and for validation of deep sequencing results. It still has the advantage over short-read sequencing technologies in that it can produce DNA sequence reads of > 500 nucleotides and maintains a very low error rate with accuracies around 99.99%. Sanger sequencing is still actively being used in efforts for public health initiatives such as sequencing the spike protein from SARS-CoV-2 as well as for the surveillance of norovirus outbreaks through the Center for Disease Control and Prevention's (CDC) CaliciNet surveillance network.
The southwestern blot, is a lab technique that involves identifying as well as characterizing DNA-binding proteins by their ability to bind to specific oligonucleotide probes. Determination of molecular weight of proteins binding to DNA is also made possible by the technique. The name originates from a combination of ideas underlying Southern blotting and Western blotting techniques of which they detect DNA and protein respectively. Similar to other types of blotting, proteins are separated by SDS-PAGE and are subsequently transferred to nitrocellulose membranes. Thereafter southwestern blotting begins to vary with regards to procedure as since the first blotting’s, many more have been proposed and discovered with goals of enhancing results. Former protocols were hampered by the need for large amounts of proteins and their susceptibility to degradation while being isolated.
The Journal of Molecular Biology is a biweekly peer-reviewed scientific journal covering all aspects of molecular biology. It was established in 1959 and is published by Elsevier. The editor-in-chief is Peter Wright.
An electrophoretic mobility shift assay (EMSA) or mobility shift electrophoresis, also referred as a gel shift assay, gel mobility shift assay, band shift assay, or gel retardation assay, is a common affinity electrophoresis technique used to study protein–DNA or protein–RNA interactions. This procedure can determine if a protein or mixture of proteins is capable of binding to a given DNA or RNA sequence, and can sometimes indicate if more than one protein molecule is involved in the binding complex. Gel shift assays are often performed in vitro concurrently with DNase footprinting, primer extension, and promoter-probe experiments when studying transcription initiation, DNA gang replication, DNA repair or RNA processing and maturation, as well as pre-mRNA splicing. Although precursors can be found in earlier literature, most current assays are based on methods described by Garner and Revzin and Fried and Crothers.
The Association of Biomolecular Resource Facilities (ABRF) is dedicated to advancing core and research biotechnology laboratories through research, communication, and education. ABRF members include over 2000 scientists representing 340 different core laboratories in 41 countries, including those in industry, government, academic and research institutions.
A molecular-weight size marker, also referred to as a protein ladder, DNA ladder, or RNA ladder, is a set of standards that are used to identify the approximate size of a molecule run on a gel during electrophoresis, using the principle that molecular weight is inversely proportional to migration rate through a gel matrix. Therefore, when used in gel electrophoresis, markers effectively provide a logarithmic scale by which to estimate the size of the other fragments.
SNP genotyping is the measurement of genetic variations of single nucleotide polymorphisms (SNPs) between members of a species. It is a form of genotyping, which is the measurement of more general genetic variation. SNPs are one of the most common types of genetic variation. An SNP is a single base pair mutation at a specific locus, usually consisting of two alleles. SNPs are found to be involved in the etiology of many human diseases and are becoming of particular interest in pharmacogenetics. Because SNPs are conserved during evolution, they have been proposed as markers for use in quantitative trait loci (QTL) analysis and in association studies in place of microsatellites. The use of SNPs is being extended in the HapMap project, which aims to provide the minimal set of SNPs needed to genotype the human genome. SNPs can also provide a genetic fingerprint for use in identity testing. The increase of interest in SNPs has been reflected by the furious development of a diverse range of SNP genotyping methods.
Nucleic acid thermodynamics is the study of how temperature affects the nucleic acid structure of double-stranded DNA (dsDNA). The melting temperature (Tm) is defined as the temperature at which half of the DNA strands are in the random coil or single-stranded (ssDNA) state. Tm depends on the length of the DNA molecule and its specific nucleotide sequence. DNA, when in a state where its two strands are dissociated, is referred to as having been denatured by the high temperature.
Nucleic acid methods are the techniques used to study nucleic acids: DNA and RNA.
The reverse northern blot is a method by which gene expression patterns may be analyzed by comparing isolated RNA molecules from a tester sample to samples in a control cDNA library. It is a variant of the northern blot in which the nucleic acid immobilized on a membrane is a collection of isolated DNA fragments rather than RNA, and the probe is RNA extracted from a tissue and radioactively labelled. A reverse northern blot can be used to profile expression levels of particular sets of RNA sequences in a tissue or to determine presence of a particular RNA sequence in a sample. Although DNA Microarrays and newer next-generation techniques have generally supplanted reverse northern blotting, it is still utilized today and provides a relatively cheap and easy means of defining expression of large sets of genes.
DNA-encoded chemical libraries (DECL) is a technology for the synthesis and screening on an unprecedented scale of collections of small molecule compounds. DECL is used in medicinal chemistry to bridge the fields of combinatorial chemistry and molecular biology. The aim of DECL technology is to accelerate the drug discovery process and in particular early phase discovery activities such as target validation and hit identification.
The northwestern blot, also known as the northwestern assay, is a hybrid analytical technique of the western blot and the northern blot, and is used in molecular biology to detect interactions between RNA and proteins. A related technique, the western blot, is used to detect a protein of interest that involves transferring proteins that are separated by gel electrophoresis onto a nitrocellulose membrane. A colored precipitate clusters along the band on the membrane containing a particular target protein. A northern blot is a similar analytical technique that, instead of detecting a protein of interest, is used to study gene expression by detection of RNA on a similar membrane. The northwestern blot combines the two techniques, and specifically involves the identification of labeled RNA that interact with proteins that are immobilized on a similar nitrocellulose membrane.
