Brake Map

Information technology volition brandish the restriction map of the sequence which enables to identify restriction sites inside the cds sequence (Fig. 14.5).

From: Bioinformatics for Everyone , 2022

MOLECULAR CHARACTERIZATION

Shmuel Razin and David Yogev , in Molecular and Diagnostic Procedures in Mycoplasmology, 1995

Introduction

Restriction endonuclease analysis (REA) of the mycoplasma genome provides a convenient and cost-constructive means of determining Dna sequence variations among strains of mollicute species. The method involves comparison of the number and size of fragments produced by digestion of the chromosomal DNA with a restriction endonuclease that cuts Dna at a constant position within a specific recognition site, ordinarily composed of 4 to 6 bp. Because of the high specificity of restriction endonucleases, complete digestion of a given genomic DNA with a specific restriction endonuclease provides a reproducible array of fragments. Separation of the fragments by agarose gel electrophoresis and staining with ethidium bromide provide a restriction blueprint that can exist compared with that of related strains. Variations in the array of fragments generated past a specific restriction endonuclease are called restriction fragment length polymorphisms (RFLPs). RFLPs can outcome from sequence rearrangements, insertion or deletion of Deoxyribonucleic acid segments, or base substitutions within the restriction endonuclease cleavage sites.

Restriction endonuclease analysis has become a most useful taxonomic tool, facilitating the identification and classification of mycoplasmal isolates as well as providing means for evaluating the caste of genotypic heterogeneity of strains within established species (Razin, 1989, 1991, 1992). In addition, REA provides valuable data on the type and number of specific nucleotide sequences in the genome, serving as a ground for construction of concrete genomic maps (Chapter B4, this volume). The great advantage of chromosomal REA is that it is universally applicable and sensitive considering the entire genome is evaluated for RFLP and, in addition, the test is relatively piece of cake to perform. Moreover, unlike SDS–PAGE of mycoplasmal prison cell proteins, REA is not susceptible to contamination by culture medium contaminants and requires very little unlabeled Deoxyribonucleic acid (three to 5 μg) per exam.

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Current and Emerging Technologies for the Diagnosis of Microbial Infections

Tanis C. Dingle , Duncan R. MacCannell , in Methods in Microbiology, 2022

ii.ane.one Restriction endonuclease assay

REA is ane of the first described and most straightforward genotypic strain typing methods. It uses an enzyme, usually HindIII, which cuts the genome sequence frequently leading to a large number of bands that can be resolved by conventional gel electrophoresis (Kuijper, Oudbier, Stuifbergen, Jansz, & Zanen, 1987; Wren & Tabaqchali, 1987). Its employ was first described in several C. difficile outbreak studies in 1987. Kuijper et al. used REA to show that two patients, who developed pseudomembranous colitis while hospitalised in the same room, were infected with the aforementioned C. difficile strain. Additionally, C. difficile isolates from the surroundings surrounding these patients were shown to take identical restriction patterns, suggesting an environmental source of infection (Kuijper et al., 1987). A second written report performed around the aforementioned period used REA to show that 10 isolates of C. difficile isolated during a infirmary outbreak were duplicate and that the profiles obtained were strain-specific (Wren & Tabaqchali, 1987). Peerbooms and colleagues collected C. difficile isolates over a four-month catamenia and subjected them to REA (Peerbooms, Kuijt, & Maclaren, 1987). They were able to distinguish 22 unlike brake types amid 38 strains, with the nearly common existence assigned to REA types A–East. These patterns correlated well to antimicrobial susceptibility patterns, though they were less discriminatory than REA typing. In 1993, Clabots et al. were the first to describe the REA method in depth and to catalogue 1965 C. difficile isolates into 206 unique REA types (Clabots et al., 1993). This seminal piece of work was the basis for currently used REA typing nomenclature.

REA remains an important epidemiologic tool in the strain typing of C. difficile and is used extensively by the Gerding laboratory at Hines, VA. Equally of 2003, their drove of C. difficile isolates, nerveless longitudinally over more than than 2 decades numbered more than than 5000, comprising at least 436 different REA types across 108 REA strain type groupings. The availability of extensive and historical REA strain typing data has been pivotal in our understanding of a number of large-scale epidemiologic studies of C. difficile, including the contempo outbreaks of NAP1/BI strains in Eastern Canada and the United States (Killgore et al., 2008; McDonald et al., 2005). While REA has been used extensively in epidemiological studies of C. difficile and has consistently demonstrated both high discriminatory power and reproducibility, interpretation of the band patterns is difficult, the protocol itself is technically demanding and the portability of resultant information betwixt laboratories is problematic. Considering of these challenges, few laboratories study the routine utilise of REA for C. difficile strain typing, although reference typing is bachelor through consultation with an REA expert laboratory.

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Speedily Growing Mycobacteria

Patricia J. Simner , ... Nancy L. Wengenack , in Molecular Medical Microbiology (Second Edition), 2022

PCR Brake Enzyme Analysis

PRA has go a valuable tool for the identification of RGM. This method requires amplification of a 441-bp region of the hsp65 gene encoding the 65-kDa heat stupor protein followed past brake enzyme analysis. The digested amplicons are run by gel electrophoresis and compared to patterns of known organisms (Fig. 95.3) [seven,22]. PRA of the hsp65 gene allows for differentiation betwixt the closely related M. abscessus and Grand. chelonae.

Figure 95.3. PRA of the hsp65 factor using restriction enzymes BsteII and HaeIii for differentiation of RGM. M. chelonae (lanes i and seven), M. abscessus subsp. abscessus (lanes 2 and 8), M. abscessus subsp. massiliense/bolletii (lanes 3 and 9) and M. fortuitum (lanes 4 and x). Lane 5, molecular mass marker.

 Figure provided courtesy of Barbara A. Brown-Elliott, Academy of Texas Wellness Science Heart, Tyler, Texas, USA.

A similar PRA method was successfully practical to the 16S–23S ITS region and was capable of differentiating between M. chelonae, M. abscessus and M. immunogenum [46].

The disadvantage of the PRA method is the apply of a complex open molecular organization with subsequent gel assay exposing the laboratory to potential amplicon contamination issues. In add-on, every bit with all other gene sequencing methods, the reliability of the results is dependent on keeping the database updated and current.

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Vibrio parahaemolyticus and Vibrio vulnificus

James D. Oliver , Jessica L. Jones , in Molecular Medical Microbiology (2d Edition), 2022

Directly Genome Restriction Analysis (DGREA)

DGREA is yet another typing method based on restriction digest of genomic Dna. In contrast to PFGE, this method employs a restriction enzyme with fewer cutting sites in the genome, resulting in smaller fragments (500–3000   bp). These fragments can, therefore, be analysed by conventional gel electrophoresis [37]. DGREA has been successfully used to differentiate pandemic strains from not-pandemic strains of V. parahaemolyticus [37,42]. While reported to have a similar discriminatory index equally PFGE [36,37], ane study identified a college frequency of untypable strains by DGREA [36].

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Assay of Gene-Specific DNA Methylation

Naoko Hattori , Toshikazu Ushijima , in Handbook of Epigenetics (Second Edition), 2022

Combined Bisulfite Restriction Analysis

COBRA is based on the appearance or disappearance of a restriction enzyme recognition site after bisulfite conversion (Fig. 8.3) [10]. Past quantifying the ratio of digested and undigested PCR products, the ratio of methylated and unmethylated DNA molecules can be quantified. This technique has the advantages of quantitative measurement of methylation levels and ease of process. However, this method is limited to the analysis of only ane CpG site. However, as multiple CpG sites within a small genomic region tend to exist coordinately methylated or unmethylated [5,11], analysis of a single CpG site can predict the methylation status of the surrounding region.

Effigy 8.3. Principles of COBRA.

Bisulfite-converted Dna is amplified past PCR with primers roofing no CpG sites, and the PCR product is digested with a restriction enzyme (TaqI). In the COBRA analysis shown hither, if the cytosine in the CpG site is methylated, the restriction site volition remain. On the other hand, if the site is unmethylated, the brake site volition be lost. Quantitative analysis of methylation levels is accomplished by subsequent gel electrophoresis and measurement of broken and uncleaved bands.

A modified protocol for COBRA, Bio-COBRA, was therefore developed [12]. Bio-COBRA incorporates an electrophoresis step of the digested PCR product in a microfluidics chip, such equally Bioanalyzer or TapeStation (Agilent), and provides a rapid and quantitative assessment of DNA methylation statuses in a large sample set.

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Use of Cosmids and Arrayed Clone Libraries for Genome Analysis

GLEN A. EVANS , ... GARY One thousand. HERMANSON , in Recombinant DNA Methodology Two, 1995

Restriction Map Determination by Oligonucleotide End Labeling

Restriction mapping of genomic Deoxyribonucleic acid carried in cosmid vectors pWE15 or sCos1 may be chop-chop and efficiently determined using a modification of a method of Smith and Birnsteil 36 for Deoxyribonucleic acid fragments, and a method of Rackwitz et al. for cosmids digested with λ-terminase. 37 Radiolabeled T3 and T7-specific oligonucleotides, commercially available as DNA sequencing primers, tin be used to find the ends of the insert following excision by NotI. 38 Using this method, the insert is separated from the vector past Non I digestion followed past partial digestion with one or more restriction enzymes. The digestion products are separated by gel electrophoresis on an agarose gel, transferred to a filter membrane, and fragments are detected by hybridization to end-specific oligomers. The restriction map may be determined from the pattern of bands detected past oligomers on the gel ( Fig. 4). This method is fast and convenient but not applicable to clones containing internal NotI sites.

FIG. iv. Restriction map analysis of cosmid clones by partial endonuclease digestion and hybridization with stop-specific oligonucleotides ("oligo end labeling"). 38 The brake map of a single cosmid in vector pWE15 was determined from Dna prepared from 1.5-ml bacterial cultures. Cosmid DNA was digested with NotI to separate the vector from insert, then digested with XhoI, EcoRI, or SmaI under atmospheric condition determined to generate partial digestion products. Restriction fragments were separate on an agarose gel, transferred to nitrocellulose membrane, and hybridized with 32 P-labeled oligonucleotides specific for the bacteriophage T3 or T7 promoters. Lanes 1–3 stand for decreasing concentrations of the indicated restriction enzyme. The T3 and T7 probes are commercially bachelor every bit DNA sequencing primers.

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Chromosomal Size Variations in Plasmodium falciparum

ALAN F. COWMAN , DAVID J. KEMP , in Mechanisms of Eukaryotic Deoxyribonucleic acid Recombination, 1992

CHROMOSOME SIZE POLYMORPHISMS GENERATED BY DELETION OF SUBTELOMERIC REPEATS

Brake maps for chromosome 1 and 2 of six cloned lines of P. falciparum take been generated (Fig. iii) (15). Two of the cloned lines were D10 and E12, which differ in the size of both chromosome 1 and 2, even though they were both derived from the same parent isolate FC27. The other clones were 3D7 and HB3, the parental clones used for a genetic cross (xvi), and two of the progeny derived from this cantankerous. The restriction maps, divers with vii dissimilar enzymes that cut the (AT)-rich genome rarely, delineate the locations of 8 genetic markers, including genes for five antigens (Fig. 3).

Fig. 3. Physical maps of P. falciparum chromosomes i and 2 in six cloned lines. Chromosome 1 is shown at the left and chromosome 2 at the correct. The figures at the left of each chromosome indicate the sizes (in kb). The position of each sequence, RESA (ring-infected erythrocyte surface antigen), pF1.three (an bearding Dna EcoRI fragment from chromosome two), tel (telomere), KAHRP (knob-associated histidine-rich poly peptide), rep (rep20), rDNA (ribosomal Dna), Ag 513, p126 is shown equally the smallest fragment to which a probe hybridized. Starting at the top, the get-go fourth dimension each sequence occurs on a chromosome, information technology is labeled with the name of the probe. When it appears again, lower in the figure, the region is identified by the shading pattern. Black semicircles represent telomeres. Brake enzymes used: A, ApaI; Bg, BgTwo; Bs, BssHII; N, NarI; Sc, SacIi; Sm, SmaI. The structure of chromosome 2 in D10 Δ2 is identical to that in D10, except in the region shown.

In all the parasites, chromosome structure is conserved in the central regions, merely is polymorphic both in length and sequence near the telomeres (15). A telomere probe, originally isolated from Plasmodium berghei (17), was known to hybridize to the telomeres of P. falciparum. The telomeric repeats are restricted to an area of less than or equal to fifteen kb from the terminate of the chromosomes, and are associated with a microheterogeneity in fragment size that is characteristic of telomeric sequences (18). An ApaI site occurs frequently in a conserved position 12–15 kb from the cease of the chromosome in many cases, even in nonhomologous chromosomes.

A P. falciparum-specific repetitive Deoxyribonucleic acid element has been described (19–21) that consists of a 21-bp core sequence and has been named rep20 (15). Clusters of this repeat occur in blocks containing at least 13 repeats, which can measure upwards to and greater than 15 kb. Rep20 sequences have been reported to reside on all chromosomes (12); however, chromosome 1 in D10 and chromosome 2 in E12 lack detectable rep20 sequences (Fig. three) (15). The rep20 sequences are associated with the ends of chromosomes, just adjacent to the telomeres (xv). Chromosome 1 of E12 has a rep20 cluster at simply one end, and it has been proposed that the generation of chromosome length polymorphism occurs by recombination within, and deletion of, expendable rep20 repeats (15,22). The maps for chromosome 1 and 2 of the six cloned lines indicate strong structural conservation in primal regions. The length polymorphisms coincide with fragments begetting rep20 repeats, and it is axiomatic that the blocks of rep20 can vary in copy number.

Small telomeric ApaI fragments that included the rep20 sequences take been found on all chromosomes (15). Nevertheless, a number of chromosomes from some clones accept one larger telomeric ApaI fragment, and all of these lack i of the rep20 domains. Consequently, it appears that the lack of a small-scale ApaI telomeric fragment correlates with the absence of the rep20 domain. It tin can be concluded, with the exception of such deletions that vary from isolate to isolate, that the general structure of each end of every chromosome is the same. It has been recently institute that rep20 deletions are as well nowadays in parasites taken directly from the field (23), and one isolate examined had rep20 deletions at both ends of chromosome 2. The results with field isolates show that these deletions are non in vitro artifacts.

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Cloning Vectors and Techniques for Exonuclease–Hybridization Restriction Mapping

KENNETH D. TARTOF , in Recombinant DNA Methodology II, 1995

Publisher Summary

Constructing brake maps of cloned Dna fragments is frequently a tiresome, simply very necessary task frequently encountered in the course of gene isolation or chromosome walking. In that location are ii methods for constructing maps of this type. The first requires digesting the cloned Deoxyribonucleic acid with two different restriction enzymes, both singly and together. Later separating the resulting fragments by agarose gel electrophoresis, a uniquely ordered arrangement that accounts for the observed array of bands in each digest can be determined by trial and error method. The corporeality of fourth dimension required for this procedure is substantial, increasing as the size of the insert Deoxyribonucleic acid increases. A second approach to brake mapping makes utilise of a method initially adult by Smith and Birnstiel. The DNA to exist mapped is uniquely labeled at one end of the molecule. And then, partial digestion with a restriction enzyme, followed past electrophoresis and autoradiography, reveals a series of fragments that can be ordered from the labeled terminus.

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Instance study: A vaccine for Aujeszky's disease

Open universiteit , Thames Polytechnic , in Biotechnological Innovations in Health Care, 1991

8.10. Biological characterisation of the two.4 N3A TK− 783 mutant

This section illustrates two important things about the 'design' of a virus to be used as a vaccine: the corporeality of work that has to be washed later on the construction of a recombinant virus and the extent of the difference there can be between a wild-type virus and a recombinant.

viii.10.one Absence of the gl gene

no gl antibodies

Restriction analysis of 2.4 N3A had suggested that the deletion had removed the gI factor. This was confirmed by showing that pigs vaccinated with 783 (ie two.four N3A TK− 783) adult a good immune response to the virus simply without whatever antibodies to gI.

viii.10.2 Absenteeism of thymidine kinase

Tin can you suggest two ways of demonstrating the absence of an active thymidine kinase gene in 783? (Recall well-nigh the way in which viruses with inactive TK genes tin can be isolated. You could too consider the metabolic activeness of thymidine kinase).
BdUr

The researchers checked for the absence of thymidine kinase (TK) activity in this strain by titration of the virus in the presence of bromodeoxyuridine (BdUr) in TK-negative mouse fibroblasts. The thymidine analogue is incorporated into the DNA of TK-positive viruses and reduces the titre because of its mutagenic effect. Table 8.three. shows that the titres of 783 is unaffected past BdUr whereas a TK-positive command strain in significantly reduced.

Table 8.3. Effects on virus titres of incubating TK+ and TK− viruses with and without Bromodeoxyuridine

Virus Virus Titre (logten)
Without BdUr With BdUr
TK+ control iv.20 3.00
783 five.lx 5.65
[xivC] thymidine

In the 2d method the virus was grown in the presence of [14C] thymidine. Incorporation of 14C into the DNA of replicating virus requires TK activity and this is assessed by the autoradiography of cells infected by PRV. The consequence for 783, by comparison with a TK+ strain, was negative.

8.10.3 Virulence, latency and spreading

Using the three backdrop of virulence, latency and spreading, write down what you think would be desirable features of a virus to be used equally a vaccine. Now compare your respond with the following:
virulence

The virulence of a potent vaccine strain is an important consideration in determining how useful information technology could be. If information technology induces clear pathological effects, it would be unacceptable; if besides avirulent information technology would non challenge the immune system sufficiently to confer protection against infection past wild-type virus. A 'good' vaccine strain must achieve a residual between the two extremes.

reactivation

Furthermore, a strain suitable for vaccination should have lost the power to go reactivated from the latent state.

Finally, a vaccine strain should only spread from animal to animal to a very limited extent, if at all.

Virulence, latency and spreading of 783 were tested together using young piglets from a pathogen-free herd. Results were as follows:

virulence: no serious clinical symptoms were observed;

latency: this was tested for by using prednisolone to suppress the immune arrangement, thereby creating the appropriate environment for reactivation of any latent virus to occur. 783 could non be reactivated by this treatment, suggesting it is incapable of beingness reactivated from the latent state in young pigs;

spreading: infection of control animals which had been allowed to come up into close contact with vaccinated animals, occurred just to a express extent, and in some experiments non at all.

8.10.4 Reversion to virulence

As will be made articulate later, information technology is virtually impossible for a double deletion mutant similar 783 to get every bit virulent as the wild type virus or fifty-fifty a unmarried mutant virus. Nevertheless, a test for reversion to virulence must be carried out. Later on serial passage of 783 through iv animals, there was no testify for any increase in virulence.

8.10.5 Safety of 783 in various conditions

The safety of strain 783 was checked in pigs of different ages and in other subcontract animals. The results obtained may be summarised as follows:

•

783 did not cause any adverse effects in 11 out of 12 sows vaccinated during pregnancy and in that location was no evidence for transmission of the virus across the placenta

•

yorkshire pigs at an historic period of 4 weeks were vaccinated with a 32-fold overdose of PRV 783 (note: the European Pharmacopoeia only requires a 10-fold overdose) and their progress compared to twelve control animals. Four of the vaccinated pigs showed very minor, transient swelling at the site of injection only otherwise the overdose had no obvious effects on the wellness and growth of the animals;

•

the response of cattle to the vaccine strain 783 was tested in calves. It was not infectious when administered intranasally. Animals injected intramuscularly did develop antibodies;

•

analogous results to those described for cattle were obtained in experiments with sheep and the same conclusion fatigued (i.e. the virus is safe).

1)

Which of the following viruses will be sensitive to bromodeoxyuridine (BdUr): Wild type PRV (strain NIA3), strain 2.4 N3A, strain 2.8 N3A strain, 2.4N3A TK-783?

two)

Which of the strains indicated in 1) is likely to lead to the least incorporation of 14C-thymidine into DNA?

3)

If a unmarried member of a herd of pigs is inoculated with NIA3, what would exist the likely consequence? What would be the result if a single fellow member of a similar herd was inoculated with 2.4 N3A TK 783?

8.10.6 Efficacy of the 783 strain

vaccine testing efficacy = low doses condom = high doses

A 'safe' virus would be of piffling utilise as a vaccine if it did not trigger an allowed response sufficient to protect the host against infection with the wild type strain. Information technology is important to annotation that the efficacy of a vaccine is generally tested with low doses of virus, in contrast to evaluation of safety which often involves high doses.

The efficacy of 783 was tested in 10-week old pigs; iii weeks after vaccination these animals and 10 others which had not been vaccinated were challenged with xfive pfu of the virulent PRV strain NIA3. The results are summarised in Tabular array 8.4. and they conspicuously betoken the value of 783 as a vaccine fifty-fifty at the low dose used (105 TCID 50 per animal).

Tabular array 8.iv. Results of challenge-infection experiments

Number of days scored
Group Pig No SN titre Temp twoscore°C SE * RS * NS * VE * GD * Expiry at Day
Vaccinated Pigs
942 eleven ane 1 0 0 4 0
946 xvi 2 ii 0 0 nd 0
947 11 three one 0 0 nd 1
948 22 iv one 0 0 5 0
952 45 one 1 0 0 3 0
955 3 5 1 1 0 nd 0
956 3 6 2 0 0 5 0
957 11 4 1 0 0 nd 0
960 xi 4 1 1 0 4 0
Mean 3.3 1.2 0.2 0 4.ii 0.i
Control pigs
943 8 11 2 2 8 >14
944 5 12 0 0 nd 0
945 four 4 iii 1 5 na 7
949 5 5 1 eight nd >14
950 8 seven iii four viii na 12
953 v 4 1 iii nd na 9
954 4 12 three 3 nd 11
958 nine xi 3 3 9 >14
961 five 4 2 ii nd na 7
962 v 4 3 two 6 na half dozen
Mean five.8 7.4 ii.1 2.8 7.2 >10.6
*
SE = Side effects including inappetance, lassitude, vomiting, diarrhoea RS = Respiratory symptoms NS = Nervous symptoms VE = Virus excretion GD = Growth depression

Notation that only slight symptoms (vomiting/diarrhoea) were observed over a express period with vaccinated pigs compared with the control grouping. Respiratory and nervous symptoms were virtually absent from the vaccinated group.

Did vaccinated pigs bear witness any depression of growth or any summit of temperature? How did this compare with the control group?

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Restriction analysis tools

Mohammad Yaseen Sofi , ... Khalid Z. Masoodi , in Bioinformatics for Anybody, 2022

15.2 What is restriction mapping?

The restriction map is the portrayal of double-stranded Deoxyribonucleic acid dependent on the situation of the restriction endonucleases cleavage sites. Digestion with uncommon brake enzymes, which every bit a rule have 6-bp recognition sites, yields few enormous Deoxyribonucleic acid parts. Virtually enzymes, then again, cut DNA all the more regularly and produce endless number of fragments (of not exactly a 100 to in excess of a 1000 bp long). Mostly, brake enzymes with 4-base recognition sites produce sections of 256 bases, while restriction enzymes with vi-base recognition sites produce fragments of 4000 bases.

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