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87-470: The Asilomar Conference on Recombinant DNA was an influential conference organized by Paul Berg , Maxine Singer , and colleagues to discuss the potential biohazards and regulation of biotechnology , held in February 1975 at a conference center at Asilomar State Beach , California. A group of about 140 professionals (primarily biologists , but also including lawyers and physicians ) participated in

174-838: A Call For Papers (CFP) or a Call For Abstracts, which is sent to prospective presenters and explains how to submit their abstracts or papers. It describes the broad theme and lists the meeting's topics and formalities such as what kind of abstract (summary) or paper has to be submitted, to whom, and by what deadline . A CFP is usually distributed using a mailing list or on specialized online services. Contributions are usually submitted using an online abstract or paper management service. Predatory conferences or predatory meetings are meetings set up to appear as legitimate scientific conferences but which are exploitative as they do not provide proper editorial control over presentations, and advertising can include claims of involvement of prominent academics who are, in fact, uninvolved. They are an expansion of

261-651: A cell that is physically separated from chromosomal DNA and can replicate independently. They are most commonly found as small circular, double-stranded DNA molecules in bacteria ; however, plasmids are sometimes present in archaea and eukaryotic organisms . Plasmids often carry useful genes, such as antibiotic resistance and virulence . While chromosomes are large and contain all the essential genetic information for living under normal conditions, plasmids are usually very small and contain additional genes for special circumstances. Artificial plasmids are widely used as vectors in molecular cloning , serving to drive

348-694: A cell through multiple generations, but at some stage, they will exist as an independent plasmid molecule. In the context of eukaryotes, the term episome is used to mean a non-integrated extrachromosomal closed circular DNA molecule that may be replicated in the nucleus. Viruses are the most common examples of this, such as herpesviruses , adenoviruses , and polyomaviruses , but some are plasmids. Other examples include aberrant chromosomal fragments, such as double minute chromosomes , that can arise during artificial gene amplifications or in pathologic processes (e.g., cancer cell transformation). Episomes in eukaryotes behave similarly to plasmids in prokaryotes in that

435-418: A cell, they must possess a stretch of DNA that can act as an origin of replication . The self-replicating unit, in this case, the plasmid, is called a replicon . A typical bacterial replicon may consist of a number of elements, such as the gene for plasmid-specific replication initiation protein (Rep), repeating units called iterons , DnaA boxes, and an adjacent AT-rich region. Smaller plasmids make use of

522-410: A conference is performed by active RFID that may indicate wilfully identified and relatively located upon approach via electronic tags. Conferences are usually organized either by a scientific society or by a group of researchers with a common interest. Larger meetings may be handled on behalf of the scientific society by a Professional Conference Organiser or PCO. The meeting is announced by way of

609-1279: A copy of the plasmid survive, while a daughter cell that fails to inherit the plasmid dies or suffers a reduced growth-rate because of the lingering poison from the parent cell. Finally, the overall productivity could be enhanced. In contrast, plasmids used in biotechnology, such as pUC18, pBR322 and derived vectors, hardly ever contain toxin-antitoxin addiction systems, and therefore need to be kept under antibiotic pressure to avoid plasmid loss. Yeasts naturally harbour various plasmids. Notable among them are 2 μm plasmids—small circular plasmids often used for genetic engineering of yeast—and linear pGKL plasmids from Kluyveromyces lactis , that are responsible for killer phenotypes . Other types of plasmids are often related to yeast cloning vectors that include: The mitochondria of many higher plants contain self-replicating , extra-chromosomal linear or circular DNA molecules which have been considered to be plasmids. These can range from 0.7 kb to 20 kb in size. The plasmids have been generally classified into two categories- circular and linear. Circular plasmids have been isolated and found in many different plants, with those in Vicia faba and Chenopodium album being

696-467: A copy to both daughter cells. These systems, which include the parABS system and parMRC system , are often referred to as the partition system or partition function of a plasmid. Plasmids of linear form are unknown among phytopathogens with one exception, Rhodococcus fascians . Plasmids may be classified in a number of ways. Plasmids can be broadly classified into conjugative plasmids and non-conjugative plasmids. Conjugative plasmids contain

783-655: A filter to select only the bacteria containing the plasmid DNA. The vector may also contain other marker genes or reporter genes to facilitate selection of plasmids with cloned inserts. Bacteria containing the plasmid can then be grown in large amounts, harvested, and the plasmid of interest may then be isolated using various methods of plasmid preparation . A plasmid cloning vector is typically used to clone DNA fragments of up to 15 kbp . To clone longer lengths of DNA, lambda phage with lysogeny genes deleted, cosmids , bacterial artificial chromosomes , or yeast artificial chromosomes are used. Another major use of plasmids

870-420: A given size) run at different speeds in a gel during electrophoresis . The conformations are listed below in order of electrophoretic mobility (speed for a given applied voltage) from slowest to fastest: The rate of migration for small linear fragments is directly proportional to the voltage applied at low voltages. At higher voltages, larger fragments migrate at continuously increasing yet different rates. Thus,

957-454: A large number of commercially available cloning and expression vectors. Insertion sequences can also severely impact plasmid function and yield, by leading to deletions and rearrangements, activation, down-regulation or inactivation of neighboring gene expression . Therefore, the reduction or complete elimination of extraneous noncoding backbone sequences would pointedly reduce the propensity for such events to take place, and consequently,

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1044-400: A part of the daily press and television news. This, in turn, stimulated knowledgeable public discussion about some of the social, political and environmental issues that emerged from genetic medicine and the use of genetically modified plants in agriculture. Another significant outcome of the conference was the precedent it set about how to respond to changes in scientific knowledge. According to

1131-646: A particular nutrient, including the ability to degrade recalcitrant or toxic organic compounds. Plasmids can also provide bacteria with the ability to fix nitrogen . Some plasmids, called cryptic plasmids , play a crucial role in horizontal genes transfer , since they carry antibiotic-resistance genes. Thus they are important factors in spreading resistance, which can result in antibiotic treatment failures. Naturally occurring plasmids vary greatly in their physical properties. Their size can range from very small mini-plasmids of less than 1-kilobase pairs (kbp) to very large megaplasmids of several megabase pairs (Mbp). At

1218-500: A plasmid containing the insulin gene leads to a large production of insulin. Plasmids may also be used for gene transfer as a potential treatment in gene therapy so that it may express the protein that is lacking in the cells. Some forms of gene therapy require the insertion of therapeutic genes at pre-selected chromosomal target sites within the human genome . Plasmid vectors are one of many approaches that could be used for this purpose. Zinc finger nucleases (ZFNs) offer

1305-411: A process called transformation . These plasmids contain a selectable marker , usually an antibiotic resistance gene, which confers on the bacteria an ability to survive and proliferate in a selective growth medium containing the particular antibiotics. The cells after transformation are exposed to the selective media, and only cells containing the plasmid may survive. In this way, the antibiotics act as

1392-428: A protective protein coat called a capsid , plasmids are "naked" DNA and do not encode genes necessary to encase the genetic material for transfer to a new host; however, some classes of plasmids encode the conjugative "sex" pilus necessary for their own transfer. Plasmids vary in size from 1 to over 400 k bp , and the number of identical plasmids in a single cell can range from one up to thousands. The term plasmid

1479-519: A series of spontaneous events that culminate in an unforeseen rearrangement, loss, or gain of genetic material. Such events are frequently triggered by the transposition of mobile elements or by the presence of unstable elements such as non-canonical (non-B) structures. Accessory regions pertaining to the bacterial backbone may engage in a wide range of structural instability phenomena. Well-known catalysts of genetic instability include direct, inverted, and tandem repeats, which are known to be conspicuous in

1566-464: A set of transfer genes which promote sexual conjugation between different cells. In the complex process of conjugation , plasmids may be transferred from one bacterium to another via sex pili encoded by some of the transfer genes (see figure). Non-conjugative plasmids are incapable of initiating conjugation, hence they can be transferred only with the assistance of conjugative plasmids. An intermediate class of plasmids are mobilizable, and carry only

1653-436: A short abstract of their presentation, which will be reviewed before the presentation is accepted for the meeting. Some organizers, and therefore disciplines require presenters to submit a paper, which is peer reviewed by members of the program committee or referees chosen by them. In some disciplines, such as English and other languages, it is common for presenters to read from a prepared script. In other disciplines such as

1740-439: A single cell is called the plasmid copy number , and is determined by how the replication initiation is regulated and the size of the molecule. Larger plasmids tend to have lower copy numbers. Low-copy-number plasmids that exist only as one or a few copies in each bacterium are, upon cell division , in danger of being lost in one of the segregating bacteria. Such single-copy plasmids have systems that attempt to actively distribute

1827-441: A specific sequence, since they can easily be purified away from the rest of the genome. For their use as vectors, and for molecular cloning , plasmids often need to be isolated. There are several methods to isolate plasmid DNA from bacteria, ranging from the plasmid extraction kits ( miniprep to the maxiprep or bulkprep) , alkaline lysis , enzymatic lysis, and mechanical lysis . The former can be used to quickly find out whether

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1914-425: A subset of the genes required for transfer. They can parasitize a conjugative plasmid, transferring at high frequency only in its presence. Plasmids can also be classified into incompatibility groups. A microbe can harbour different types of plasmids, but different plasmids can only exist in a single bacterial cell if they are compatible. If two plasmids are not compatible, one or the other will be rapidly lost from

2001-406: A suitable host. However, plasmids, like viruses , are not generally classified as life . Plasmids are transmitted from one bacterium to another (even of another species) mostly through conjugation . This host-to-host transfer of genetic material is one mechanism of horizontal gene transfer , and plasmids are considered part of the mobilome . Unlike viruses, which encase their genetic material in

2088-525: A way to cause a site-specific double-strand break to the DNA genome and cause homologous recombination . Plasmids encoding ZFN could help deliver a therapeutic gene to a specific site so that cell damage , cancer-causing mutations, or an immune response is avoided. Plasmids were historically used to genetically engineer the embryonic stem cells of rats to create rat genetic disease models. The limited efficiency of plasmid-based techniques precluded their use in

2175-433: Is a mix of pre-recorded and live presentations. Because virtual or hybrid events allow people from different time zones to participate simultaneously, some will have to participate during their night-time. Some virtual conferences try to mitigate this issue by alternating their schedule in a way so that everyone has the chance to participate at day time at least once. Prospective presenters are usually asked to submit

2262-435: Is demonstrated by using a suitable host that can mass produce specialized metabolites, some of these molecules are able to control microbial population. Plasmids can contain and express several BGCs with a few plasmids known to be exclusive for transferring BGCs. BGC's can also be transfers to the host organism's chromosome, utilizing a plasmid vector, which allows for studies in gene knockout experiments. By using plasmids for

2349-438: Is normally inserted into a plasmid that typically contains a number of features for their use. These include a gene that confers resistance to particular antibiotics ( ampicillin is most frequently used for bacterial strains), an origin of replication to allow the bacterial cells to replicate the plasmid DNA, and a suitable site for cloning (referred to as a multiple cloning site ). DNA structural instability can be defined as

2436-609: Is supported by bioinformatics software . These programs record the DNA sequence of plasmid vectors, help to predict cut sites of restriction enzymes , and to plan manipulations. Examples of software packages that handle plasmid maps are ApE, Clone Manager , GeneConstructionKit, Geneious, Genome Compiler , LabGenius, Lasergene, MacVector , pDraw32, Serial Cloner, UGENE , VectorFriends, Vector NTI , and WebDSV. These pieces of software help conduct entire experiments in silico before doing wet experiments. Many plasmids have been created over

2523-412: Is to make large amounts of proteins. In this case, researchers grow bacteria containing a plasmid harboring the gene of interest. Just as the bacterium produces proteins to confer its antibiotic resistance, it can also be induced to produce large amounts of proteins from the inserted gene. This is a cheap and easy way of mass-producing the protein, for example, utilizing the rapid reproduction of E.coli with

2610-476: The hok/sok (host killing/suppressor of killing) system of plasmid R1 in Escherichia coli . This variant produces both a long-lived poison and a short-lived antidote . Several types of plasmid addiction systems (toxin/ antitoxin, metabolism-based, ORT systems) were described in the literature and used in biotechnical (fermentation) or biomedical (vaccine therapy) applications. Daughter cells that retain

2697-461: The predatory publishing business model, which involves the creation of academic publications built around an exploitative business model that generally involves charging publication fees to authors without providing the editorial and publishing services associated with legitimate journals. BIT Life Sciences and SCIgen are some of the conferences labeled as predatory. Academic conferences are criticized for being environmentally unfriendly, due to

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2784-424: The sciences , presenters usually base their talk around a visual presentation that displays key figures and research results. A large meeting will usually be called a conference, while a smaller is termed a workshop. They might be single track or multiple track , where the former has only one session at a time, while a multiple track meeting has several parallel sessions with speakers in separate rooms speaking at

2871-637: The Committee on Recombinant DNA molecules of the National Academy of Science, U.S.A., held in 1974, concluded that an international conference was necessary to resolve the issue and that until that time, scientists should halt experiments involving recombinant DNA technology. The Asilomar Conference on Recombinant DNA took place at the Asilomar Conference Center on California's Monterey Peninsula in 1975. The main goal of

2958-416: The DNA at certain short sequences. The resulting linear fragments form 'bands' after gel electrophoresis . It is possible to purify certain fragments by cutting the bands out of the gel and dissolving the gel to release the DNA fragments. Because of its tight conformation, supercoiled DNA migrates faster through a gel than linear or open-circular DNA. The use of plasmids as a technique in molecular biology

3045-624: The DNA is stably maintained and replicated with the host cell. Cytoplasmic viral episomes (as in poxvirus infections) can also occur. Some episomes, such as herpesviruses, replicate in a rolling circle mechanism, similar to bacteriophages (bacterial phage viruses). Others replicate through a bidirectional replication mechanism ( Theta type plasmids). In either case, episomes remain physically separate from host cell chromosomes. Several cancer viruses, including Epstein-Barr virus and Kaposi's sarcoma-associated herpesvirus , are maintained as latent, chromosomally distinct episomes in cancer cells, where

3132-515: The Democratic National Committee headquarters in 1972. Two years after the burglary, taped evidence was discovered that indicated that President Nixon had discussed a cover-up a week after it. Three days following the release of the tape, Nixon resigned from his presidential office. This event focused the nation's attention on the problem of government secrecy fostering illegal and immoral behavior and it has been suggested by

3219-548: The Watson-Crick model yielded theoretical advances that were reflected in new capacities to manipulate DNA. One of these capacities was recombinant DNA technology. This technology entails the joining of DNA from different species and the subsequent insertion of the hybrid DNA into a host cell. One of the first individuals to develop recombinant DNA technology was a biochemist at Stanford by the name of Paul Berg. In his experimental design in 1974, he cleaved (cut into fragments)

3306-711: The amount of airplane traffic generated by them. A correspondence on Nature.com points out the "paradox of needing to fly to conferences" despite increased calls for sustainability by environmental scientists. The academic community's carbon footprint is comprised in large parts by emissions caused by air travel. Few conferences enacted practices to reduce their environmental impact by 2017, despite guidelines being widely available: An analysis of academic conferences taking place in 2016 showed that only 4% of 116 conferences sampled offered carbon offset options and only 9% of these conferences implemented any form of action to their reduce environmental impact. More conferences included

3393-412: The boundary between a chromosome and a plasmid, found in about 10% of bacterial species sequenced by 2009. These elements carry core genes and have codon usage similar to the chromosome, yet use a plasmid-type replication mechanism such as the low copy number RepABC. As a result, they have been variously classified as minichromosomes or megaplasmids in the past. In Vibrio , the bacterium synchronizes

3480-973: The cell. Different plasmids may therefore be assigned to different incompatibility groups depending on whether they can coexist together. Incompatible plasmids (belonging to the same incompatibility group) normally share the same replication or partition mechanisms and can thus not be kept together in a single cell. Another way to classify plasmids is by function. There are five main classes: Plasmids can belong to more than one of these functional groups. Although most plasmids are double-stranded DNA molecules, some consist of single-stranded DNA , or predominantly double-stranded RNA . RNA plasmids are non-infectious extrachromosomal linear RNA replicons, both encapsidated and unencapsidated, which have been found in fungi and various plants, from algae to land plants. In many cases, however, it may be difficult or impossible to clearly distinguish RNA plasmids from RNA viruses and other infectious RNAs. Chromids are elements that exist at

3567-415: The central problems of classical genetics became more apparent. Two main underlying concepts of this tradition were that genes consisted of DNA and that DNA encoded information that determined the processes of replication and protein synthesis . These concepts were embodied in the model of DNA produced through the combined efforts of James Watson , Francis Crick , and Rosalind Franklin . Further research on

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3654-562: The circular plasmids share a common ancestor, some genes in the mitochondrial plasmid have counterparts in the nuclear DNA suggesting inter-compartment exchange. Meanwhile, the linear plasmids share structural similarities such as invertrons with viral DNA and fungal plasmids, like fungal plasmids they also have low GC content, these observations have led to some hypothesizing that these linear plasmids have viral origins, or have ended up in plant mitochondria through horizontal gene transfer from pathogenic fungi. Plasmids are often used to purify

3741-516: The conference proceedings . Usually a conference will include keynote speakers (often, scholars of some standing, but sometimes individuals from outside academia). The keynote lecture is often longer, lasting sometimes up to an hour and a half, particularly if there are several keynote speakers on a panel . In addition to presentations, conferences also feature panel discussions , round tables on various issues, poster sessions and workshops. Some conferences take more interactive formats, such as

3828-427: The conference advocated the use of additional safety factors. One such factor was physical containment, exemplified by the use of hoods or where applicable, limited access or negative pressure laboratories. Another factor was the strict adherence to good microbiological practices, which would limit the escape of organisms from the experimental situation. Additionally, the education and training of all personnel involved in

3915-595: The conference marked the beginning of an exceptional era for both science and the public discussion of science policy. The guidelines devised by the conference enabled scientists to conduct experiments with recombinant DNA technology, which by 1995 dominated biological research. This research, in turn, increased knowledge about fundamental life processes, such as the cell cycle. Additionally, the conference along with public debates on recombinant DNA, increased public interest in biomedical research and molecular genetics. For this reason, by 1995, genetics and its vocabulary had become

4002-580: The conference to draw up voluntary guidelines to ensure the safety of recombinant DNA technology. The conference also placed scientific research more into the public domain, and can be seen as applying a version of the precautionary principle . The effects of these guidelines are still being felt through the biotechnology industry and the participation of the general public in scientific discourse. Due to potential safety hazards, scientists worldwide had halted experiments using recombinant DNA technology, which entailed combining DNAs from different organisms. After

4089-412: The conference was to address the biohazards presented by recombinant DNA technology. During the conference, the principles guiding the recommendations for how to conduct experiments using this technology safely were established. The first for dealing with potential risks was that containment should be made an essential consideration in the experimental design. A second principle was that the effectiveness of

4176-427: The conference, the proper response to new scientific knowledge was to develop guidelines that governed how to regulate it. Academic conference Conferences usually encompass various presentations . They tend to be short and concise, with a time span of about 10 to 30 minutes; presentations are usually followed by a discussion . The work may be bundled in written form as academic papers and published as

4263-429: The construction of recombinant DNA molecules and their propagation involved prokaryotic agents that were known to exchange genetic information naturally. For experiments involving the creation and propagation of recombinant DNA molecules from DNAs of species that ordinarily did not exchange genetic information and generate novel biotypes, the experiments were to be performed in at least in a low risk containment facility. If

4350-491: The containment should match the estimated risk as closely as possible. The conference also suggested the use of biological barriers to limit the spread of recombinant DNA. Such biological barriers included fastidious bacterial hosts that were unable to survive in natural environments. Other barriers were nontransmissible and equally fastidious vectors ( plasmids , bacteriophages , or other viruses) that were able to grow in only specified hosts. In addition to biological barriers,

4437-586: The creation of a biotechnology industry, although during this time, public debates occur over the hazards of recombinant DNA. These debates were eventually won over by scientists who stated that the hazards were exaggerated and that the research could be conducted safely. Such was seen in the Ascot report, found in the Federal Register in March 1978. This report emphasized that the hazards of recombinant DNA to

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4524-489: The creation of more accurate human cell models. However, developments in adeno-associated virus recombination techniques, and zinc finger nucleases , have enabled the creation of a new generation of isogenic human disease models . Plasmids assist in transporting biogenetic gene clusters - a set of gene that contain all the necessary enzymes that lead to the production of special metabolites (formally known as secondary metabolite) . A benefit of using plasmids to transfer BGC

4611-489: The environment and infect laboratory workers. These workers could then become cancer victims. Concern about this potential biohazard, along with others, caused a group of leading researchers to send a letter to the president of the National Academy of Science (NAS). In this letter, they requested that he appoint an ad hoc committee to study the bio-safety ramifications of this new technology. This committee, called

4698-416: The establishment of the guidelines during the conference, scientists continued with their research, which increased fundamental knowledge about biology and the public's interest in biomedical research . Recombinant DNA technology arose as a result of advances in biology that began in the 1950s, and '60s. During these decades, a tradition of merging the structural, biochemical and informational approaches to

4785-481: The experiment increased the pathogenicity of the recipient species or result in new metabolic pathways in species, then moderate or high-risk containment facilities were to be used. In experiments where the range of resistance of established human pathogens to therapeutically useful antibiotics or disinfectants was extended, the experiments were to be undertaken only in moderate or high-risk containment facilities. When working with animal viruses, experiments that involved

4872-425: The experiments that were conducted, the guidelines also forbade the performance of other experiments. One such experiment was the cloning of recombinant DNAs derived from highly pathogenic organisms. In addition, neither the cloning of DNA containing toxin genes, nor large scale experiments using recombinant DNAs that were able to make products that were potentially harmful to humans, animals or plants were allowed under

4959-449: The experiments would be essential to effective containment measures. The Asilomar Conference also gave recommendations for matching the types of containment necessary for different types of experiments. These recommendations were based on the different levels of risk associated with the experiment, which would require different levels of containment. These levels were minimal, low, moderate and high risk. The minimal risk level of containment

5046-463: The general community were small to the point that they were of no practical consequence to the general public. For this reason, along with high economic pressures for industrial development and a more supportive political environment that existed after 1979, research and industry based on recombinant DNA continued to expand. Years after the conference, people ascribed a large amount of significance to it. According to Paul Berg and Maxine Singer in 1995,

5133-586: The guidelines. These experiments were banned because the potential biohazards could not be contained by the then current safety precautions. The participants of the Asilomar Conference also endeavored to bring science into the domain of the general public, with a possible motivation being the Watergate scandal . The scandal resulted from a bungled break-in at the Watergate hotel, which served as

5220-416: The host cells, for example: enabling the host cell to survive in an environment that would otherwise be lethal or restrictive for growth. Some of these genes encode traits for antibiotic resistance or resistance to heavy metal, while others may produce virulence factors that enable a bacterium to colonize a host and overcome its defences or have specific metabolic functions that allow the bacterium to utilize

5307-410: The host replicative enzymes to make copies of themselves, while larger plasmids may carry genes specific for the replication of those plasmids. A few types of plasmids can also insert into the host chromosome, and these integrative plasmids are sometimes referred to as episomes in prokaryotes . Plasmids almost always carry at least one gene. Many of the genes carried by a plasmid are beneficial for

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5394-557: The linkage of viral genomes or genome segments to prokaryotic vectors and their propagation in prokaryotic cells were to be conducted only with vector-host systems that had demonstrated restricted growth capabilities outside the laboratory and in moderate risk containment facilities. As safer vector-host systems became available, such experiments could be performed in low risk facilities. In experiments designed to introduce or propagate DNA from non-viral or other low risk agents in animal cells, only low risk animal DNA could be used as vectors and

5481-500: The manipulations were to be confined to moderate risk containment facilities. With eukaryotes, attempts to clone segments of DNA using recombinant DNA technology from warm-blooded vertebrates genomes were to be performed only with vector-host systems that had demonstrably restricted growth capabilities outside the laboratory and in a moderate risk containment facility. This was because they potentially contained cryptic viral genomes that were potentially pathogenic to humans. However, unless

5568-495: The monkey virus SV40. He then cleaved the double helix of another virus; an antibacterial agent known as bacteriophage lambda . In the third step, he fastened DNA from the SV40 to DNA from the bacteriophage lambda. The final step involved placing the mutant genetic material into a laboratory strain of the E. coli bacterium. This last step, however, was not completed in the original experiment. Berg did not complete his final step due to

5655-530: The most studied and whose mechanism of replication is known. The circular plasmids can replicate using the θ model of replication (as in Vicia faba ) and through rolling circle replication (as in C.album ). Linear plasmids have been identified in some plant species such as Beta vulgaris , Brassica napus , Zea mays , etc. but are rarer than their circular counterparts. The function and origin of these plasmids remains largely unknown. It has been suggested that

5742-441: The organism made a dangerous product, recombinant DNAs from cold-blooded vertebrates and all other lower eukaryotes could be constructed and propagated with the safest vector-host system available in low risk containment facilities. Additionally, purified DNA from any source that performed known functions and was judged to be non-toxic could be cloned with available vectors in low risk containment facilities. In addition to regulating

5829-429: The overall recombinogenic potential of the plasmid. Plasmids are the most-commonly used bacterial cloning vectors. These cloning vectors contain a site that allows DNA fragments to be inserted, for example a multiple cloning site or polylinker which has several commonly used restriction sites to which DNA fragments may be ligated . After the gene of interest is inserted, the plasmids are introduced into bacteria by

5916-543: The participant driven " unconference " or various conversational formats. Academic conferences have been held in three general formats: in-person, virtual or online and hybrid (in-person and virtual). Conferences have traditionally been organized in-person. Since the COVID-19 pandemic many conferences have either temporarily or permanently switched to a virtual or hybrid format. Some virtual conferences involve both asynchronous and synchronous formats. For example, there

6003-675: The plasmid is correct in any of several bacterial clones. The yield is a small amount of impure plasmid DNA, which is sufficient for analysis by restriction digest and for some cloning techniques. In the latter, much larger volumes of bacterial suspension are grown from which a maxi-prep can be performed. In essence, this is a scaled-up miniprep followed by additional purification. This results in relatively large amounts (several hundred micrograms) of very pure plasmid DNA. Many commercial kits have been created to perform plasmid extraction at various scales, purity, and levels of automation. Plasmid DNA may appear in one of five conformations, which (for

6090-424: The pleas of several fellow investigators, including Robert Pollack , who feared the biohazards associated with the last step. The SV40 was known to cause cancer tumors to develop in mice. Additionally, the E. coli bacterium (although not the strain used by Berg) inhabited the human intestinal tract. For these reasons, the other investigators feared that the final step would create cloned SV40 DNA that might escape into

6177-414: The political scientist Ira H. Carmen that this motivated the scientists at the Asilomar Conference to bring science into the public eye to ensure that they would not be accused of a cover-up. Additionally, according to Dr. Berg and Dr. Singer, by being forthright, scientists avoided restrictive legislation due to the development of a consensus on how they were to conduct their research. Bringing science into

6264-496: The preferred term for autonomously replicating extrachromosomal DNA. At a 1968 symposium in London some participants suggested that the term episome be abandoned, although others continued to use the term with a shift in meaning. Today, some authors use episome in the context of prokaryotes to refer to a plasmid that is capable of integrating into the chromosome. The integrative plasmids may be replicated and stably maintained in

6351-428: The previously mentioned safety measures, formed the basis for the guidelines used by investigators in future experiments that involved the construction and propagation of recombinant DNA molecules using DNA from prokaryotes , bacteriophages and other plasmids , animal viruses and eukaryotes . For prokaryotes, bacteriophages and other plasmids, experiments could be performed in minimal risk containment facilities when

6438-489: The program. Business meetings for learned societies , interest groups , or affinity groups can also be part of the conference activities. Academic conferences typically fall into three categories: Increasing numbers of amplified conferences are being provided which exploit the potential of WiFi networks and mobile devices in order to enable remote participants to contribute to discussions and listen to ideas. Advanced technology for meeting with any yet unknown person in

6525-465: The public eye also coincided with the rapid rate at which recombinant DNA technology entered the industrial world. Because of the practical applications of the technology, funding for research using it started coming more from the private sector and less from the public sector. In addition, many molecular biologists who once confined themselves to academia, developed ties with private industry as equity owners, corporate executives and consultants. This led to

6612-479: The replication of recombinant DNA sequences within host organisms. In the laboratory, plasmids may be introduced into a cell via transformation . Synthetic plasmids are available for procurement over the internet by various vendors using submitted sequences typically designed with software, if a design does not work the vendor may make additional edits from the submission. Plasmids are considered replicons , units of DNA capable of replicating autonomously within

6699-443: The replication of the chromosome and chromid by a conserved genome size ratio. Artificially constructed plasmids may be used as vectors in genetic engineering . These plasmids serve as important tools in genetics and biotechnology labs, where they are commonly used to clone and amplify (make many copies of) or express particular genes. A wide variety of plasmids are commercially available for such uses. The gene to be replicated

6786-493: The resolution of a gel decreases with increased voltage. At a specified, low voltage, the migration rate of small linear DNA fragments is a function of their length. Large linear fragments (over 20 kb or so) migrate at a certain fixed rate regardless of length. This is because the molecules 'respirate', with the bulk of the molecule following the leading end through the gel matrix. Restriction digests are frequently used to analyse purified plasmids. These enzymes specifically break

6873-489: The same time. However, there are no commonly shared definitions even within disciplines for each event type. There might be no conceivable difference between a symposium, a congress or a conference. The larger the conference, the more likely it is that academic publishing houses may set up displays. Large conferences also may have a career and job search and interview activities. At some conferences, social or entertainment activities such as tours and receptions can be part of

6960-402: The upper end, little differs between a megaplasmid and a minichromosome . Plasmids are generally circular, but examples of linear plasmids are also known. These linear plasmids require specialized mechanisms to replicate their ends. Plasmids may be present in an individual cell in varying number, ranging from one to several hundreds. The normal number of copies of plasmid that may be found in

7047-463: The uptake of BGCs, microorganisms can gain an advantage as production is not limited to antibiotic resistant biosynthesis genes but the production of toxin s/antitoxins. The term episome was introduced by François Jacob and Élie Wollman in 1958 to refer to extra-chromosomal genetic material that may replicate autonomously or become integrated into the chromosome. Since the term was introduced, however, its use has changed, as plasmid has become

7134-478: The use of teleconferencing after the COVID-19 pandemic. In-person conferences suffer from a number of issues. Most importantly, they are fostering the existing social inequality in academia due to their inaccessibility for researchers from low income countries, researchers with care duties or researchers facing visa restrictions. Plasmid A plasmid is a small, extrachromosomal DNA molecule within

7221-478: The viruses express oncogenes that promote cancer cell proliferation. In cancers, these episomes passively replicate together with host chromosomes when the cell divides. When these viral episomes initiate lytic replication to generate multiple virus particles, they generally activate cellular innate immunity defense mechanisms that kill the host cell. Some plasmids or microbial hosts include an addiction system or postsegregational killing system (PSK), such as

7308-508: Was coined in 1952 by the American molecular biologist Joshua Lederberg to refer to "any extrachromosomal hereditary determinant." The term's early usage included any bacterial genetic material that exists extrachromosomally for at least part of its replication cycle, but because that description includes bacterial viruses, the notion of plasmid was refined over time to refer to genetic elements that reproduce autonomously. Later in 1968, it

7395-417: Was decided that the term plasmid should be adopted as the term for extrachromosomal genetic element, and to distinguish it from viruses, the definition was narrowed to genetic elements that exist exclusively or predominantly outside of the chromosome, can replicate autonomously, and contribute to transferring mobile elements between unrelated bacteria. In order for plasmids to replicate independently within

7482-494: Was intended for experiments in which the biohazards could be accurately assessed and were expected to be minimal. Low risk containment was appropriate for experiments that generated novel biotypes but where the available information indicated that the recombinant DNA could not either alter appreciably the ecological behavior of the recipient species, increase significantly its pathogenicity or prevent effective treatments of any resulting infections. The moderate risk level of containment

7569-435: Was intended for experiments in which there was a probability of generating an agent with a significant potential for pathogenicity or ecological disruption. High-risk containment was intended for experiments in which the potential for ecological disruption or pathogenicity of the modified organism could be severe and thereby pose a serious biohazard to laboratory personnel or to the public. These levels of containments, along with

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