Navigation Links
Phage


A phage (also called bacteriophage) (in Greek phageton = food/consumption) is a small virus that infects only bacteria. Like viruses that infect eukaryotes, phages consist of an outer protein hull and the enclosed genetic material (which consists of double-stranded DNA in 95% of the phages known) of 5 to 650 kbp (kilo base pairs) with a length of 24 to 200 nm. The vast majority of phages (95%) have a tail to let them inject their genetic material into the host. Phages were discovered independently by Frederick Twort in 1915 and by Flix d’Herelle in 1917. d'Herelle continued his research and development in Stalin's Soviet Union.

Phages infect only specific bacteria. Some phages are virulent, meaning that upon infecting a cell they immediately begin reproducing, and within a short time lyse (destroy) the cell, releasing new phages. (A famous quote from the microbiologist Mark Mller says: Bacteria don't die, they just phage away.) Some phages (so-called temperate phages) can instead enter a relatively harmless state, either integrating their genetic material into the chromosomal DNA of the host bacterium (much like endogenous retroviruses in animals) or establishing themselves as plasmids. These endogenous phages, referred to as prophages, are then copied with every cell division together with the DNA of the host cell. They do not kill the cell, but monitor (via some proteins they code for) the status of their host. When the host cell shows signs of stress (meaning it might be about to die soon), the endogenous phages become active again and start their reproductive cycle, resulting in the lysis of the host cell. An example is phage λ of E. coli. Sometimes, prophages even provide benefit to the host bacterium while they are dormant, by adding new functions to the bacterial genome, a phenomenon called lysogenic conversion. A famous example is the harmless Vibrio bacteria strain, which is turned into Vibrio cholerae by a phage, causing cholera.

Phages play an important role in molecular biology as cloning vectors to insert DNA into bacteria. Phage therapy has been used since the 1940s in the former Soviet Union as an alternative to antibiotics for treating bacterial infections—because killing bacteria is what phages do best. There is an extensive library of research into specific phages and their therapeutic uses in the Tbilisi Institute in Georgia. The development of bacterial strains that are resistant to multiple drugs has led Western medical researchers to re-evaluate phages as alternatives to the use of antibiotics.

Phage display is a test to screen for protein interactions by integrating multiple genes from a gene bank into phages.

Model bacteriophages

Following is a list of bacteriophages that are extensively studied:

See also


'"/>


(Date:4/27/2015)... 27, 2015 NXT-ID, Inc. (NASDAQ: NXTD ... focused on the growing mobile commerce market, announces that ... customers the first week of May, 2015 and will ... May. Gino Pereira , Chief ... the company as Wocket® enters the consumer market. We ...
(Date:4/21/2015)... Canada , April 21, 2015 ... and evolving government policies are boosting access control systems ... According to a recently published report by ... Opportunities, 2020 ", the access control systems market in ... nearly USD1.2 billion by 2020.The access control systems market ...
(Date:4/20/2015)... The announcement comes as demand ... Management (GRM), Ireland,s foremost records management ... built up an impressive track record of clients within the ... the records management sector in Dubai . ... staffbase and employ a further eight staff members at its ...
Breaking Biology News(10 mins):Wocket, the Smartest Wallet You Will Ever Own, Announces Shipment to Pre-order Customers 2Wocket, the Smartest Wallet You Will Ever Own, Announces Shipment to Pre-order Customers 3Saudi Arabia Access Control Systems Market to Touch USD1.2 Billion by 2020 Says TechSci Research 2Saudi Arabia Access Control Systems Market to Touch USD1.2 Billion by 2020 Says TechSci Research 3Glenbeigh Records Management Wins Contract With Dubai Islamic Bank 2Glenbeigh Records Management Wins Contract With Dubai Islamic Bank 3
... years ago about the time early human tribes were ... called Neodenticula seminae went extinct in the North ... resident again, having drifted from the Pacific through the Arctic ... The melting Arctic has opened a Northwest Passage across the ...
... Office of Naval Research (ONR) Global is reaching ... members at MAST Europe 2011, June 27-29, in ... technology inventions and showcasing the organization,s efforts. ... leaders from more than 40 countries to discuss ...
... of vitamins and minerals to the human diet globally ... to a new study published in the international online ... was carried out by an interdisciplinary research team, comprised ... the Leuphana University of Lneburg, the University of Berlin ...
Cached Biology News:Prodigal plankton species makes first known migration from Pacific to Atlantic via Pole 2Prodigal plankton species makes first known migration from Pacific to Atlantic via Pole 3Prodigal plankton species makes first known migration from Pacific to Atlantic via Pole 4Prodigal plankton species makes first known migration from Pacific to Atlantic via Pole 5Prodigal plankton species makes first known migration from Pacific to Atlantic via Pole 6Office of Naval Research Global connecting with international naval community at MAST Europe 2011 2Pollinators make critical contribution to healthy diets 2
Other biology definitionOther Tags