Aptamers are short DNA or RNA oligonucleotides with high, specific affinity to a special target. The name was originated from aptus that means "to fit" and meros that shows the polymer identity of oligonucleotides (1, 2). Aptamer characteristics provide prominent potential applications in multiple fields.These nucleic acid ligands are completely generated through in vitro process for a wide range of targets from small molecules and ions to large proteins and cells and even whole organism or tissue. Their chemical modifications could be easily performed to improve the intended specificity. Meanwhile, they keep their stability against various conditional stresses and show lower toxicity and immunogenicity than other specific ligands e.g. monoclonal antibodies. Because of the high specificity, adaptability, and ease of modification, aptamers have been used in a broad range of applications, including affinity purification, drug discovery, high-throughput screening, drug delivery, medical diagnostics and biosensors (3-5).
In molecular biology, there are several methods that could help researchers for in vitro evolution of single stranded oligonucleotide pools to high affinity ligands like aptamers. In vitro evolution is the experimental process in which large random-sequence pools of RNA or DNA are used as the starting point and particular nucleic acid sequences with higher affinity to an intended target are identified as aptamers. This type of selection and evolution is termed
In making PNA a prospect for drugs, researchers have demonstrated proof of concept for using PNA oligomers to activated or suppress the transcription, replication, or repair of specific genes by binding DNA is various ways. PNA oligomers and conventional nucleic acids have the same problem of poor bioavailability because they are large water loving molecules making it difficult for them to enter cells. The productions of PNA based drugs awaits the development of suitable chemical modifications or pharmaceutical formulations to improve PNA bioavailability. Researchers believe this is the only thing holding back this medical breakthrough.
CRISPR stands for Clustered Regularly Interspaced Short Palindromic Repeat, referring to the repeating DNA sequences found in the genomes of microorganisms. CRISPR technology allows scientists to make precise changes in genes by splicing and replacing these DNA sequences with new ones. Through these changes, the biology of the cell is altered and possibly affects the health of an organism. The possibilities are endless as this offers opportunities in curing deadly diseases, modifying genes, and changing humanity as we know it. Although bioengineering has been around since the 1960s, CRISPR is significant because of the comparative low costs and the ease of the procedure to
DNA, Deoxyribonucleic Acid, is the basic structure for all life, it is the blueprint, the instruction manual, on how to build a living organism. DNA is made up of four nitrogen bases, adenine, thymine, cytosine, and guanine which are connected by sugar-phosphate bonds. Through a process called Protein Synthesis, the nitrogen bases are the code for the creation of amino acids. Essentially, DNA makes amino acids, amino acids make proteins, proteins make organisms. This process has been taking place for much longer than scientists have been able to document. Those scientists are called geneticists and their field is genetics.
Marker assisted selection (MAS) is a method using fluoresces to determine whether there are mutations in a particular gene. One form of MAS is Fluorescence in situ Hybridization (FISH), in which the target gene (ADA gene) is denatured (splits into single strands) in a solution containing a direct DNA probe which has an identical base pair sequence to the ADA gene being analyzed (these DNA probes are also denatured into single strands). A direct DNA probe is made up of modified dNTPs which have been altered to contain a fluorophore (a fluorescent chemical compound that has the ability to re-emit light upon mild excitation), these will bind to the ADA gene strands if there are no mutations present (i.e. it is a fully functioning gene). If
In this experiment, host NM554, a particular strain of E. coli, was used to cultivate human genes (Dolf, 2013). Through the use of cosmids, plasmids that carry the cos gene, DNA fragments were introduced into the E. coli and packaged into phage particles (McClean, 1998). Pst I is a restriction endonuclease, an enzyme that cuts DNA at restriction sites (Restriction endonuclease). The Pst I digest of human DNA in this study produced the DNA fragments that were examined. The dideoxynucleotide chain-reaction procedure, also known as Sanger sequencing, is the process of lengthening DNA using DNA polymerase to add on deoxynucleotides until a dideoxynucleotide is added on randomly (Rogers). Fluorescence in situ hybridization (represented by the acronym
The Combined DNA Index System or CODIS is defined as a program used by the FBI which stores DNA data on a national level. As such, CODIS combines science and computer technology creating an avenue enabling federal, local, and state law enforcement agencies to connect violent crimes by electronically exchanging and comparing the DNA profiles of offenders, thus providing possible connections to other crimes committed and associations with other known
DNA profiling is a forensic technique used to identify individuals by characteristics of their DNA. A DNA profile is a small set of DNA variations that is very likely to be different in all unrelated individuals, thereby being as unique to individuals as are fingerprints. First developed and used in 1985, DNA profiling is used in, for example, parentage testing and criminal investigation, to identify a person or to place a person at a crime scene, techniques which are now employed globally in forensic science to facilitate police detective work and help clarify paternity and immigration disputes. This essay is one that will be discussing DNA profiling strengths and weaknesses, what it entails, limitations and how such evidence is presented
Genetic engineering has been impossible until recent times due to the complex and microscopic nature of DNA and its component nucleotides. Through progressive studies, more and more in this area is being made possible.
Sensitivity of duplex Real-time-PCR compared microscopic detection of M. bovis: Results revealed that out of 600 lymph node sample with lesions suggestive to tuberculosis 580 (96.6%) was positive for AFB detected by microscopic examination of ZN stained smears. However, by duplex real-time PCR 588 (98%) was confirmed to M. bovisinfection. Analytical specificity: The specificity of real-time PCR targeting IS1081 and IS6110 was evaluated to 19 strains of different Mycobacterial species. The real-time PCR targeting both IS1081 and IS6110 sequences showed negative result with all Mycobacterial A. Selim et el.
RESULTS AND DISCUSSION PCR and dsRNA production Target sequences of 1501, 1576, 1650, 1750, 538, and 716 bp specific for gyrase A, gyrase rpo B1, rpo B2 and GFP were successfully amplified with PCR (data not shown).. The in vitro transcription using T7 enzyme resulted in target specific dsRNA of 1501, 1576, 1650, 1750, 538, and 716 bp for each of gyrase A, gyrase B, rpo B1, rpo B2, L11, and GFP genes, respectively (Fig.1). In vitro growth inhibition assay B. bovis growth (Fig. 2) from an initial parasitemia of 1% was significantly (ANOVA) inhibited at 10 µg/ml and 50
With the advancement of sequencing technology, vast information on DNA sequences of many animal genomes has been developed (Goff et al. 2002; Yu et al. 2002). In order to correlate DNA sequence information with particular a phenotype of a trait, sequence-specific molecular marker techniques have been designed. Expressed sequence tags (EST) analysis is one such type. By adopting this method, Expressed sequence tags of many animal species have been created and these sequences are subjected as putative functional genes by using advanced bioinformatics tools.
can limit starting library total amount. Also the concentration of salt and the temperature changes which can be happening during the electrophoresis run, so according to all that we can say the conditions of final binding of the aptamer is difficult to be under full control. Another related tactic which using the affinity of chromatography also has been applied, but this tactic surrounded by the problem of low level of reaction. DNA aptamer was selected against human immunoglobulin E (IgE) by using the microfluidic free flow electrophoresis (μFFE) device, in order to compare μFFE to capillary electrophoresis based selections, μFFE gives the ability to upload approximately~300-fold more library (1014molecules) by using a continuous flow
Spinach was discovered using the Systematic Evolution of Ligands by Exponential Enrichment (SELEX) technique against DFHBI immobilized on agarose resin. People have developed Spinach- based sensors against adenosine, ADP, S-adenosyl-methionine (SAM), guanine, cyclic-di-GMP (c-di-GMP) and GTP using existing aptamer sequences. A key challenge for RNA-based sensors is that they normally function poorly in cells. This is because RNA is easily degraded by nuclease and also has poor folding in intracellular. Poor folding RNA can be contributed by many elements, such as the difference folding structures and thermal instability, or rely on ion concentration. Later people developed 49-nt-long aptamer-Broccoli, which has brighter green fluorescence upon binding DFHBI. Folding of Broccoli only needs low concentration of magnesium and the Mg2+ presents low amount in body so Broccoli can fold better than Spinach. Broccoli also has a higher thermostability than Spinach. Additionally, Broccoli does not require a tRNA scaffold to promote its folding in vivo.
Biosensor that optimizes this interaction may also be known as genosensors. The recognition is based on DNA’s complementary bases. Once, they are able to detect its targeted nucleic acid, the complementary base sequence can be synthesize, labeled and immobilized by the sensor.
DNA fingerprinting is a scientific technology involving the extraction, replication and arrangement of strands of an organism’s DNA. This results in the formation of a genetically distinctive fingerprint that is unique to the organism which the DNA sample was originally extracted from. Because of the specificity of a DNA fingerprint, the application of this technology can have a substantial influence on many aspects of society. Accessibility to a DNA database allows for higher efficiency in forensic investigations, personal identification, maternal and paternal testing. The availability of a national database to police officers and forensic scientists would equate to increased productivity in investigations and prosecution of suspects in a