Nitrogenous Base

The nitrogenous bases, adenine, cytosine, guanine, thymine and uracil, comprising the nucleic acids are derived from certain amino acids and their precursors (Fig. 8).

From: Encyclopedia of Food Microbiology , 1999

Nucleic Acids

Antonio Blanco , Gustavo Blanco , in Medical Biochemistry, 2017

Nucleotides

Nucleotides include: (i) a nitrogenous base of operations, (2) a 5-carbon monosaccharide (aldopentose), and (3) phosphoric acid.

Nitrogenous bases. Nucleotide hydrolysis produces two types of substances derived from the heterocyclic rings purine and pyrimidine known equally the purine and pyrimidine bases. Fig. 6.ane shows their chemic structure and the numbering of the elements in the molecule. Purines are derived from pyrimidines by addition of an imidazole grouping. Both purines and pyrimidines have all their atoms on the aforementioned airplane.

Figure 6.i. Numbering of pyrimidine elements is different to that of purine.

Only carbons 2 and 5 have the same number in both cycles.

Nucleic acids contain five dissimilar nucleotide bases. Iii are pyrimidines and two purines. The pyrimidine bases are thymine (five-methyl-2,4-dioxipyrimidine), cytosine (ii-oxo-iv-aminopyrimidine), and uracil (two,4-dioxoypyrimidine) (Fig. half-dozen.2).

Figure 6.ii. Pyrimidine bases.

Purine bases include adenine (6-aminopurine) and guanine (2-amino-half-dozen-oxypurine) (Fig. six.3).

Figure vi.3. Purine bases.

Pyrimidine and guanine bases in Figs. 6.2 and six.3 represent to the ketone or lactam forms of these nucleotides, which predominate in natural products. In that location are isomers (tautomers) that produce the enol or lactim grade of these nucleotides, which be in much lower proportion. These isomers are produced by displacement of the hydrogen atom leap to the neighboring nitrogen toward the oxygen. Eventually, nucleic acids may comprise a modest amount of other bases that derive from the main ones, such as v-methyl-cytosine.

Due to their aromatic nature, purine and pyrimidine bases absorb radiation in the ultraviolet (UV) region of the spectrum, with a maximum at a wavelength of 260 nm. This property allows to place nucleic acids in a sample and to estimate their concentration past spectrophotometry.

Aldopentoses. The monosaccharide that forms nucleic acids can exist d-ribose or d-2-deoxyribose. Co-ordinate to the pentose present, two kinds of nucleic acids can be distinguished: ribonucleic acids (RNAs) and deoxyribonucleic acids (DNAs). The aldopentoses in nucleic acids adopt the furanose form (Fig. 6.4) (carbons of the pentose are distinguished from those of the base past calculation a quotation mark, i′, 2′, etc.).

Figure vi.4. Aldoses nowadays in nucleic acids.

Both ribose or deoxyribose, through their carbon one′ are linked to nitrogen ix of the purine or nitrogen i of the pyrimidine bases past a β-glycosidic bond, which allows their complimentary rotation. The compound formed by a nitrogenous base of operations, purine or pyrimidine and aldopentose is called nucleoside. The relative spatial organization of the nitrogenous base of operations and the monosaccharide varies between the two main configurations shown in Fig. half-dozen.five. These correspond to the syn and anti forms. The latter is thermodynamically more favorable (Fig. 6.six).

Figure 6.5. Adenosine (nucleoside).

(A) syn form; (B) anti grade.

Figure 6.6. Thymidine (nucleoside).

A nucleotide is formed by esterification with phosphoric acid of the hydroxyl group in carbon 5′ of the ribose or deoxyribose that forms part of the nucleoside (Fig. 6.7).

Figure 6.vii. Guanylic acid or guanosine monophosphate (nucleotide, anti course).

Read full chapter

URL:

https://world wide web.sciencedirect.com/science/commodity/pii/B9780128035504000069

Purine and Pyrimidine Metabolism

Antonio Blanco , Gustavo Blanco , in Medical Biochemistry, 2017

Summary

Humans produce nitrogenous bases endogenously and are not dependent on dietary intake of purines and pyrimidines.

Purine biosynthesis involves the formation of the purine ring from residues of different origins. C4, C5, and N7 are derived from glycine; N3 and N9 are derived from the amide group of glutamine; N1 is derived from aspartate; C2 and C8 come up from formyl residues donated by formyl tetrahydrofolate; C6 is derived from COii. The molecular assembly is performed with ribose-5-P bound to it. First, PRPP is formed through a reaction catalyzed by phosphoribosylpyrophosphate synthetase, an enzyme inhibited past the end products, AMP, GMP, IMP. Finally a nucleotide is obtained.

Salvage pathway for purine synthesis requires the activity of APRT and hypoxanthine-guanine phosphoribosyl transferase.

Purine catabolism starts with the degradation of nucleic acids into nucleosides and nucleotides. Adenosine is deaminated (catalyzed by adenosine deaminase). Inosine formed is cleaved by phosphorylation (catalyzed by nucleoside phosphorylase) to produce hypoxanthine and ribose-P.

Then, hypoxanthine is oxidized to xanthine (catalyzed by xanthine oxidase). Guanosine is hydrolyzed to guanine and ribose. Guanine is deaminated to xanthine (catalyzed past guanase). Xanthine, formed from both adenine and guanine, is oxidized into uric acid (catalyzed by xanthine oxidase).

Uric acrid is the stop product of purine catabolism in humans. It is poorly soluble and is mainly excreted in the urine.

The concentration of uric acid in normal plasma is 4–6 mg/dL. In some pathological conditions this value increases.

Gout is a disease characterized by elevated levels of urate in the blood and urine. Urate precipitates causing arthritis and kidney stones.

Pyrimidine biosynthesis requires the binding of aspartate and carbamoyl phosphate. Carbamoyl phosphate is synthesized from the amide grouping of glutamine and CO2 (catalyzed past CPS 2). The reaction of carbamoyl-phosphate and aspartate forms carbamoylaspartate (catalyzed past aspartate transcarbamoylase), which is cyclized forming orotic acid. Aspartate transcarbamoylase is the main regulatory site of the pathway, it is inhibited by the end products (UTP, CTP).

Pyrimidine catabolism renders soluble compounds, which can be hands removed or used.

Degradation of cytosine produces β-alanine, CO2, and NHiii. Thymine produces β-aminoisobutyrate, CO2, and NH3. β-Aminoisobutyrate is converted into succinyl-CoA.

Biosynthesis of nucleoside di-and triphosphate are obtained from nucleoside monophosphate past phosphoryl transfer from other nucleoside triphosphates (catalyzed by nucleoside kinase).

Deoxyribonucleotide biosynthesis is obtained by reduction of ribose already bound to the nucleotide past ribonucleotide reductase. NADPH and thioredoxin are required.

Read full chapter

URL:

https://world wide web.sciencedirect.com/scientific discipline/article/pii/B9780128035504000185

Mediators of the Inflammatory Reaction

K. ROCHA E SILVA , J. GARCIA LEME , in Chemical Mediators of the Acute Inflammatory Reaction, 1972

Displacement Theory

Many simple nitrogenous bases have been found to release histamine, and the simplest of all, ammonia, was constitute to be very stiff ( Garan, 1938; Schild, 1949). Alkaloids, such as atropine, strychnine and curare (or D-tubocurarine), were found to release histamine from various structures (Burstein and Parrot, 1949; Alam et al., 1939; Schild and Gregory, 1947). The release of histamine from the perfused dog's gastrocnemius by curare was demonstrated past Alam et al. (1939) and confirmed by 'Schild and Gregory (1947). Perfusion of the rat'south hindlimbs through a cannula tied in the abdominal aorta showed release of histamine when D-tubocurarine was injected into the cannula (Rocha due east Silva and Schild, 1949). In this blazon of experiment, repeated injections of curare acquired a repeated liberation of histamine and very large quantities may be released in full. In each example a loftier tooth ratio of curarine/histamine varying from 20 to 51 could be observed and amounts varying from five to 35.6μg could be released by 2-6 mg of D-tubocurarine. In guild to have more than accurate data on the quantities of histamine that are released by D-tubocurarine, Rocha e Silva and Schild (1949) adult the simple technique of using a piece of rat'south diaphragm to study the histamine-releasing capacity of D-tubocurarine. The ii lateral portions of the diaphragm were used as command pairs. Later on careful washing of the diaphragm, each half, weighing approximately 150 to 300 mg, was attached to platinum hooks fused into the tip of capillary glass tubes, transferred to warm oxygenated Tyrode solution and thence into the experimental solution containing d-tubocurarine. After a measured fourth dimension the musculus was removed from the solution and transferred to a fresh solution of d-tubocurarine. The histamine actualization in the solution was assayed upon the isolated guinea pig gut. Effigy 31 summarizes 106 individual measurements of histamine release by curarine.

FIG. 31. Summary of 106 individual measurements of histamine release past d- tubocurarine, the area of each circle being proportional to the number of observations. Blackness circles: release with concentration of d-tubocurarine of ane mg/ml or more than; white circles: 0.five mg/ml; squares: 0.25 mg/ml. The gradient of line A has been used for the calculation of the diffusion constant.

 (According to Rocha e Silva and Schild, 1949.) Copyright © 1949

A number of substituted amines, containing the guanidine group or related radicals, were tested past MacIntosh and Paton (1949) for histamine-liberating capacity. Amongst the bases studied were diamines, diamidines, diguanidines, diisothioureas, diquaternaries and some benzamidine derivatives. Many of them produced a sudden autumn of arterial pressure after a latency of 20–25 seconds, when given intravenously to cats and dogs. Many of such compounds—diamino-octane, diamidinodecane, diguanidinopentane, diisothioureas—produced wheals when injected in the homo pare. The supposition that such compounds act past liberating histamine was confirmed for at least two of them, propamidine and one,8-diamino-octane, past estimating and identifying histamine in the blood of cats and dogs given these simple compounds in a dose range of 5–15 mg/kg of trunk weight. Similar results were too obtained with the antibiotic polypeptide, licheniformin, extracted from Bacillus licheniformis by Unconversant et al. (1947). Injection of diamino-octane dihydrochloride (15 mg/kg) in the vein of a dog was followed past a abrupt ascent of blood histamine (up to 3μg/ml of plasma) and incoagulability of the blood which remained fluid for more than 24 hours. Addition of toluidine bluish brought the clotting time back to normal indicating that heparin was the agent responsible for this increase in clotting time. The similarity betwixt the effects of these simple bases and those produced by injected peptone suggests that they human action by a common mechanism. This belief is further strengthened by the fact that a basic polypeptide similar licheniformin is able to produce similar furnishings. The suggestion that peptone or the antigen in anaphylaxis might work by releasing unproblematic bases like diamines and diamidines appears to be a more remote possibility.

Chemical compound 48/lxxx obtained by condensation of p-methoxy-phenethylmethylamine with formaldehyde was found to be the most potent of all basic releasers (Paton, 1951; Mongar and Schild, 1952; Feldberg and Talesnik, 1953). It is interesting to annotation that this chemical compound besides releases heparin from dog'south liver (MacIntosh, personal advice) just not from rat'due south organs (Mota et al., 1953) although it produces a rapid destruction of mast cells in the rat'due south skin. The possibility of a like compound being 1 of the mediators in anaphylactic daze was postulated by Mongar and Schild (1952) who showed a correlation between the proportion of histamine prepare free from different tissues of the guinea pig when put into contact with compound 48/80 or with egg albumin. Notwithstanding hitting this parallelism, sure peculiarities in the mode of action of each amanuensis precludes whatsoever idea that in anaphylaxis the final mediator for the histamine release might be a comparable uncomplicated compound. For example a previous application of 48/fourscore to pieces of intestine increased considerably the output of histamine which followed contact with the egg albumin, while by reversing the order of addition, egg albumin had no effect upon the further release produced by 48/80. Furthermore, those compounds do not stimulate the shine muscle of the republic of guinea-hog gut and do not release in vivo histamine from the intestinal tract (Feldberg and Talesnik, 1953). It seems likely that those compounds work through some intermediary amanuensis nowadays in sure organs (rat's peel, for instance) but not in others.

More consummate surveys of the bones agents which have been shown to release histamine can exist found in Paton (1957) and Rothschild (1966).

The possibility of a simple displacement of histamine by basic compounds, in a way similar to that caused in a cationic exchange resin by stronger bases, was causeless past many to explain the release of histamine by 48/80, diamines, diamidines and so forth. This theory has been supported past some findings that histamine can be retained by heparin in solution, and since the mast cells are very rich in acrid sulfated polysaccharides, these might found a natural site for histamine retention inside the mast-cells granules, prior to release. Some straight bear witness of such histamine binding to heparin was presented by Lagunoff et al. (1964) and Uvnäs (1964), equally we accept seen above. Only these experiments accept only proved that a minor part of histamine (no more than 1-5th) could be retained in the mast-cells granules by such salt linkage.

It has always been difficult to understand why in the anaphylactic stupor of the dog, histamine and heparin are both released from liver mast cells in a free form, and at that place is no evidence for the participation of whatsoever basic chemical compound which could possibly combine with heparin in the places previously occupied past histamine. Furthermore, the mechanism of release of histamine by basic compounds (48/80) from rat mast cells appears to bear a potent similarity to the mechanism of release of histamine past anaphylaxis and anaphylatoxin, from the guinea-pig lung and rabbit platelets, structures upon which the basic compounds take a small-scale issue or none at all. This point volition be discussed in the adjacent section where the machinery of release volition be described in relation to activation or inhibition of enzymes of the carbohydrate metabolism.

Read full chapter

URL:

https://www.sciencedirect.com/scientific discipline/commodity/pii/B9780080170404500077

Bacterial Genetics

David P. Clark , Nanette J. Pazdernik , in Molecular Biology (Second Edition), 2013

Whole Genome Sequencing of Bacteria

•

For most bacteria, genetic information has been gathered by sequencing the whole genome.

The first bacterium to take its entire genome sequenced was Haemophilus influenzae. Rapid advances in sequencing technology have led to many completed sequences for a wide range of leaner, including many important pathogens.

Additionally, differences in nitrogenous base content of DNA molecules and codon usage frequencies bespeak segments of the genome with foreign origins.

•

Genome specialization islands are blocks of contiguous genes unremarkably with a "strange" origin that perform some specialized function, such as virulence or biodegradation.

Comparisons of genome sequences between harmless and pathogenic bacterial relatives have indicated big sections of genes responsible for virulence. These are known equally pathogenicity islands and are a specific blazon of specialization islands. Other "islands" might encode genes for the deposition of chemical pollutants, such as petroleum, herbicides, and industrial chemicals.

•

Whole bacterial genomes have been chemically synthesized and successfully inserted into bacterial cells.

The Venter Found has performed some, once idea, impossible feats. These include the complete chemical manufacturing of a bacterium's genome, followed by whole genome transformation into a new cell.

Read total chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780123785947000603

Nucleic Acids: DNA and RNA

Chang-Hui Shen , in Diagnostic Molecular Biology, 2019

Nitrogenous Base

The five-carbon saccharide ring and the content of the nitrogenous base of operations between Deoxyribonucleic acid and RNA are slightly different from each other. Four different types of nitrogenous bases are found in DNA: adenine (A), thymine (T), cytosine (C), and guanine (G). In RNA, the thymine is replaced by uracil (U). The chemic structures of A, G, C, T, and U are shown in ( Fig. 1.5A ). Because of their structural similarity, we normally refer the nine-fellow member double rings adenine and guanine equally purines, and six-member unmarried-ring thymine, uracil, and cytosine are pyrimidines.

Fig. 1.5

Fig. 1.5

Fig. 1.5. (A) Chemical structure of pyrimidines and purines nitrogenous bases in Deoxyribonucleic acid and RNA. (B) Chemical structure of ribose and ii-deoxyribose that are found in RNA and DNA, respectively.

Read total chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9780128028230000018

Dna Repair

Yara Khodour , ... Johnny Stiban , in The Enzymes, 2019

iii.i.three Glycosylases

DNA glycosylases initiate BER by cleaving the glycosidic bond between damaged nitrogenous bases and the pentose moiety [174–176]. Endonuclease III, which is the glycosylase that functions in removing oxidized pyrimidines from duplex Deoxyribonucleic acid, was institute to contain a [4Fe-4S] cluster. Similarly the adenine and weak guanine glycosylase (MutY) and a family of uracil DNA glycosylases are cluster containing [174,177]. Recent studies suggest that the glycosylase domain containing the cluster is involved in Deoxyribonucleic acid binding; the interaction of the iron–sulfur cluster domain with Dna affects directly the efficiency of lesion detection and removal [178]. The [4Fe-4S] clusters found in DNA glycosylases can undergo oxidation when the domain contacts DNA. Binding of DNA shifts the redox potential of the cluster, whereby it becomes oxidized, transferring an electron to well-nigh likely another glycosylase through the DNA via charge transport. The reduced cluster in the remote glycosylase renders the enzyme weakly associated with the Deoxyribonucleic acid and thus it is removed. In damaged Dna, the glycosylase maintains the oxidized cluster and remains leap to Deoxyribonucleic acid, promoting repair [179]. It likewise seems likely that the redox behavior of Deoxyribonucleic acid glycosylases, which is mediated by their iron–sulfur clusters, scans the Dna for damaged bases to initiate repairs [22,67,178].

Read full chapter

URL:

https://world wide web.sciencedirect.com/scientific discipline/article/pii/S1874604719300095

Biological macromolecules acting on gastrointestinal systems

Dilipkumar Pal , Supriyo Saha , in Biological Macromolecules, 2022

thirteen.5 Role of nucleic acids in gastrointestinal system

Nucleic acid is the most important biological macromolecule composed of 2 nitrogenous bases (purine and pyrimidine) continued via phosphodiester linkage with ribose sugar backbone ( Dahm, 2008). Nucleic acids are mainly ii types such as deoxyribonucleic acid and ribonucleic acid. Nucleic acids played an important role in replication and poly peptide synthesis (Cox & Nelson, 2008). Nucleic acids are also showed its activity toward different disorders related to GS (Lander et al., 2001). In this relation, long noncoding ribonucleic acid showed its greater efficacy against inflammation associated with celiac affliction and IBS; in this scenario gluten costless diet creates a positive response (Lashgarian, Karkhane, Marzban, Yazdi, & Shahzamani, 2020) (Fig. 13.10).

Figure 13.10. Comparison of lncRNA13 expression level in salubrious individuals and celiac disease patients.

 Source: Copyright permission granted from Lashgarian et al. (2020) Elsevier Ltd.

In the management of cancer related to GS, purine nucleoside as eight-hydroxy-deoxyguanosine, glutathione created a positive relation with oxidative stress linked with cancer (Gonenc, Hacısevki, Aslan, Torun, & Simsek, 2012). In relation with long coding ribonucleic acid to pancreatic cancer. The outcomes showed that nonpancreatic cancer patients showed greater expression of long coding ribonucleic acrid and activated tumor growth factor beta with lesser chance of survival as well as the chances of tumor metastasis was reduced (Cheng, Fu, Li, & Jiang, 2020). A new GS cancer biomarker DDX39 showed its function in the diagnosis of GS tumor. DDX39 showed its activity through adenosine triphosphate dependent ribonucleic acid helicase enzyme as confirmed by immunohistochemical analysis (Kikuta et al., 2020). Visceral smoothen muscle is the important characteristic of GS smoothen muscle evolution. In this way, posttranscriptional modification of messenger ribonucleic acid and its related multiple splicing-two are the critical steps for the development of visceral shine musculus formation; for this way colon tissue of pediatrics with Hirschsprung'south disease and chronic pseudo obstruction syndrome showed greater expression of ribonucleic acid binding protein related to multiple splicing-2 and showed proper linked for GS visceral smoothen musculus evolution (Notarnicola et al., 2012). Also improver of double stranded ribonucleic acid into the inner cell persuaded posttranscription of factor silencing machinery associated with gastrointestinal track movement and cellular characteristics (Sklan & Glenn, 2007). Furthermore, a new ribonucleic acid binding LIN28 protein was expressed with gastric hepatoid and hepatocellular cancers as compare to other markers such as sal-similar protein 4, alpha fetoprotein, glypican-iii, antihepatocyte specific antigen, carcinoembryonic antigen and cytokeratin 7. The outcomes showed that LIN28 was highly expressed in both the cancers but not effective as other markers (Zhao et al., 2018).

Read full affiliate

URL:

https://www.sciencedirect.com/science/commodity/pii/B9780323857598000130

Introduction to genes and genomes

Nachimuthu Saraswathy , Ponnusamy Ramalingam , in Concepts and Techniques in Genomics and Proteomics, 2011

ane.half dozen Composition and structure of Dna

Deoxyribonucleic acrid (Deoxyribonucleic acid) is made upwardly of sugar, a nitrogenous base of operations and a phosphate group ( Effigy 1.ii). The combination of these molecules makes the building blocks for the DNA synthesis. The sugar present in the Deoxyribonucleic acid is ii'deoxyribose, a 5 carbon monosaccharide, which is devoid of oxygen in its 2' position, hence the name deoxyribonucleic acrid. The carbon atoms present in the deoxyribose are numbered 1', two', 3', iv' and v'. Nitrogenous bases nowadays in the DNA tin can be grouped into two categories: purines (Adenine (A) and Guanine (G)), and pyrimidine (Cytosine (C) and Thymine (T)). These nitrogenous bases are attached to C1' of deoxyribose through a glycosidic bond. Deoxyribose attached to a nitrogenous base of operations is called a nucleoside. A nucleoside attached to a phosphate grouping is known equally a nucleotide. The nucleotides are linked together by phosphodiester bonds. Many nucleotides attached together are known as polynucleotides.

Figure ane.2. Dna is made up of five carbon sugar (deoxyribose), 1 phosphate group and 4 bases. The combination of these molecules makes the building blocks for the Dna synthesis.

Once Deoxyribonucleic acid was confirmed as the genetic material, scientists were bang-up to find out its chemical construction. When Wilkins and Rosalind were on the verge of solving the structure of DNA, Watson and Crick proposed their famous double helical structure of DNA in 1953 by combining the findings of Chargaff (i.e. molar concentrations of adenine equal those of guanine, and of cytosine equal those of thymine) with the Ten-ray diffraction data of DNA fibre. The biological course of Deoxyribonucleic acid is made upwardly of two complementary polynucleotide strands wound about each other to form a complete construction. The sugar and phosphate groups form the backbone and bases formed the cadre of the Dna double helix. The two strands run in opposite directions and are denoted equally five' to 3', every bit the ends that have the complimentary phosphate group and the costless OH groups at the terminus, respectively. Polynucleotide double-stranded Dna has a regular helix with 10 base pairs per turn. Base of operations pairing is an important aspect of the DNA double helix as it helps in DNA replication and transcription.

Read full chapter

URL:

https://www.sciencedirect.com/science/article/pii/B9781907568107500018

Neuro-Oncology

Frank Attenello , ... Alessandro Olivi , in Handbook of Clinical Neurology, 2012

Chemotherapeutic selection/information

Carmustine (BCNU) exerts cytotoxic issue by means of alkylation of the nitrogenous bases of DNA. It has a low molecular weight and depression lipid solubility, compatible with little resistance to passage by the BBB ( Walker et al., 1980). Because BCNU is lipophilic and, therefore, delivered by systemic routes with more ease than other chemotherapeutic agents, its utilise every bit the first selected agent for local delivery is frequently questioned. BCNU was chosen primarily because of the wealth of information from previous studies. The use of polymer for delivery, too every bit large local CNS concentrations of drug, in contrast, were not well studied, with studies desiring minimization of unknowns (Brem et al., 1991). In addition, BCNU has dose-limiting side-effects of bone marrow suppression and pulmonary fibrosis, likewise as a relatively short half-life (<   fifteen   min), limiting systemic delivery. Finally, systemic administration of BCNU was non associated with a significant prolongation of the survival of patients with encephalon tumors (Walker et al., 1980). Local delivery of BCNU thus offered the opportunity to decrease toxicity and increase the efficacy of a well-studied compound.

Read full affiliate

URL:

https://www.sciencedirect.com/science/commodity/pii/B9780444521385000220

Book 3

G. Dorado , ... P. Hernández , in Encyclopedia of Biomedical Engineering, 2019

Oxford Nanopore Technologies Sequencing

The Oxford Nanopore Technologies sequencing is a engineering science based on the detection of the nitrogenous bases residues of complimentary nucleotides (or even nucleic acid polymers) every bit they motility through pores embedded in a lipid bilayer on microwells arrayed on a silicon chip ( Bayley et al., 2010). In short, the ssDNA generated from dsDNA randomly fragmented past nebulization is immobilized on nanopores. Then the ion electric current variations being generated every bit the nucleotides excised by an exonuclease or as the intact ssDNA passes through the nanopore is detected on hundreds of thousands of parallel reactions on nanopores on microwells on silicon chips. Eventually, bioinformatics tools are used to assemble the sequencing reads into contigs, chromosomes and the genome ( Effigy 10 ).

Figure 10. Oxford Nanopore Technologies sequencing. This sequencing methodology is based on the immobilization of ssDNA on nanopores, and subsequent detection of the ion electric current variations as the excised nucleotides or intact nucleic acids passes through the nanopore on microwells on silicon fries. The readings are finally assembled with bioinformatics tools.

There are different variations of the bones arroyo, like for instance the single-molecule exonuclease sequencing on protein nanopores, the unmarried-molecule strand sequencing on protein nanopores (using a DNA polymerase to brand the ssDNA pass through the nanopore), and the unmarried-molecule sequencing on synthetic nanopores. Due to its technological nature, the Oxford Nanopore Technologies technology can sequence directly non only single-molecule Dna, but also unmarried-molecule RNA. Therefore, this third-generation sequencing approach is more similar to the Helicos BioSciences tSMS sequencing than to the Pacific Biosciences SMRT or Complete Genomics cPAL sequencing methodologies.

Read total chapter

URL:

https://world wide web.sciencedirect.com/scientific discipline/article/pii/B9780128012383089984