Hepatitis C and hepatitis B viruses both attack the liver, eventually causing deadly cirrhosis or cancer. But while antivirals can cure 95% of HCV infections, its cousin HBV has long eluded effective therapeutics. As a result, ...
Apr 13, 2023
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Rice University synthetic biologists have developed a new way to study a sensory system that salmonella, E. coli and other pathogens use to sicken millions of people each year.
Dec 12, 2022
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For some laboratory workers a positive test for SARS-CoV-2 may more accurately indicate an occupational exposure rather than a viral infection. This week in Microbiology Spectrum, researchers in Seattle report on a small ...
Oct 13, 2022
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Bacteria that cause infections in hospitals are increasingly becoming resistant to antibiotics, and a group of bacterial species called Enterobacterales that are able to fend off a type of antibiotic called carbapenems are ...
Apr 19, 2022
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Coronavirus disease 2019 (COVID-19) has become a global pandemic. Currently, SARS-CoV-2 live virus-associated experiments need to be handled in biosafety level 3 (BSL-3) facilities. Previously, researchers had successfully ...
Dec 6, 2021
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Toxin-antitoxin (TA) systems are now known to negatively control plasmid replication, according to Thomas Wood, Biotechnology Endowed Chair and professor of chemical engineering in the Penn State College of Engineering.
Feb 1, 2021
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Severe ulcerative colitis—a form of inflammatory bowel disease (IBD)—has been linked to a newly-discovered strain of oral bacteria, a study led by UNSW Sydney has found.
Oct 29, 2020
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A probiotic drink could become a promising new weapon in the battle against antibiotic resistant bacteria, after a team of scientists at the University of Birmingham engineered and patented a key genetic element that can ...
Jan 15, 2020
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A recent research led by a scientist at City University of Hong Kong (CityU) has discovered an easily transmitted DNA piece that can make a new type of hyper-resistant and deadly superbug become hyper-virulent quickly, posing ...
Oct 23, 2019
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Antibiotic-resistant organisms can be found in multiple locations in a hospital - on countertops and doorknobs, on computers and in sinks, and even inside the plumbing. To better understand how these organisms spread, investigators ...
Feb 6, 2018
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In microbiology and genetics, a plasmid is a DNA molecule that is separate from, and can replicate independently of, the chromosomal DNA. They are double-stranded and, in many cases, circular. Plasmids usually occur naturally in bacteria, but are sometimes found in eukaryotic organisms (e.g., the 2-micrometre ring in Saccharomyces cerevisiae).
Plasmid sizes vary from 1 to over 1,000 kbp. The number of identical plasmids in a single cell can range anywhere from one to even thousands under some circumstances. Plasmids can be considered part of the mobilome because they are often associated with conjugation, a mechanism of horizontal gene transfer.
The term plasmid was first introduced by the American molecular biologist Joshua Lederberg in 1952.
Plasmids are considered "replicons", capable of autonomous replication within a suitable host. Plasmids can be found in all three major domains: Archaea, Bacteria, and Eukarya. Similar to viruses, plasmids are not considered by some to be a form of "life". Unlike viruses, plasmids are "naked" DNA and do not encode genes necessary to encase the genetic material for transfer to a new host, though some classes of plasmids encode the sex pilus necessary for their own transfer. Plasmid host-to-host transfer requires direct, mechanical transfer by conjugation or changes in host gene expression allowing the intentional uptake of the genetic element by transformation. Microbial transformation with plasmid DNA is neither parasitic nor symbiotic in nature, because each implies the presence of an independent species living in a commensal or detrimental state with the host organism. Rather, plasmids provide a mechanism for horizontal gene transfer within a population of microbes and typically provide a selective advantage under a given environmental state. Plasmids may carry genes that provide resistance to naturally occurring antibiotics in a competitive environmental niche, or the proteins produced may act as toxins under similar circumstances. Plasmids can also provide bacteria with the ability to fix elemental nitrogen or to degrade recalcitrant organic compounds that provide an advantage when nutrients are scarce.
This text uses material from Wikipedia, licensed under CC BY-SA
