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In the resolution phase of recombination , any Holliday junctions formed by the strand invasion process are cut , thereby restoring two separate DNA molecules . This cleavage is done by RuvAB complex interacting with RuvC , which together form the RuvABC complex . RuvC is an endonuclease that cuts the degenerate seque... |
= = = Facilitating genetic transfer = = =
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Homologous recombination is an important method of integrating donor DNA into a recipient organism 's genome in horizontal gene transfer , the process by which an organism incorporates foreign DNA from another organism without being the offspring of that organism . Homologous recombination requires incoming DNA to be ... |
In bacterial conjugation , where DNA is transferred between bacteria through direct cell @-@ to @-@ cell contact , homologous recombination helps integrate foreign DNA into the host genome via the RecBCD pathway . The RecBCD enzyme promotes recombination after DNA is converted from single @-@ strand DNA – in which for... |
= = = Bacterial transformation = = =
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Natural bacterial transformation involves the transfer of DNA from a donor bacterium to a recipient bacterium , where both donor and recipient are ordinarily of the same species . Transformation , unlike bacterial conjugation and transduction , depends on numerous bacterial gene products that specifically interact to ... |
As part of the transformation process , the RecA protein interacts with entering single @-@ stranded DNA ( ssDNA ) to form RecA / ssDNA nucleofilaments that scan the resident chromosome for regions of homology and bring the entering ssDNA to the corresponding region , where strand exchange and homologous recombination... |
= = In viruses = =
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Homologous recombination occurs in several groups of viruses . In DNA viruses such as herpesvirus , recombination occurs through a break @-@ and @-@ rejoin mechanism like in bacteria and eukaryotes . There is also evidence for recombination in some RNA viruses , specifically positive @-@ sense ssRNA viruses like retro... |
In RNA viruses , homologous recombination can be either precise or imprecise . In the precise type of RNA @-@ RNA recombination , there is no difference between the two parental RNA sequences and the resulting crossover RNA region . Because of this , it is often difficult to determine the location of crossover events ... |
Homologous recombination is important in facilitating viral evolution . For example , if the genomes of two viruses with different disadvantageous mutations undergo recombination , then they may be able to regenerate a fully functional genome . Alternatively , if two similar viruses have infected the same host cell , ... |
Homologous recombination is the proposed mechanism whereby the DNA virus human herpesvirus @-@ 6 integrates into human telomeres .
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When two or more viruses , each containing lethal genomic damage , infect the same host cell , the virus genomes can often pair with each other and undergo homologous recombinational repair to produce viable progeny . This process , known as multiplicity reactivation , has been studied in several bacteriophages , incl... |
= = Effects of dysfunction = =
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Without proper homologous recombination , chromosomes often incorrectly align for the first phase of cell division in meiosis . This causes chromosomes to fail to properly segregate in a process called nondisjunction . In turn , nondisjunction can cause sperm and ova to have too few or too many chromosomes . Down 's s... |
Deficiencies in homologous recombination have been strongly linked to cancer formation in humans . For example , each of the cancer @-@ related diseases Bloom 's syndrome , Werner 's syndrome and Rothmund @-@ Thomson syndrome are caused by malfunctioning copies of RecQ helicase genes involved in the regulation of homo... |
Decreased rates of homologous recombination cause inefficient DNA repair , which can also lead to cancer . This is the case with BRCA1 and BRCA2 , two similar tumor suppressor genes whose malfunctioning has been linked with considerably increased risk for breast and ovarian cancer . Cells missing BRCA1 and BRCA2 have ... |
= = Evolutionary Conservation = =
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While the pathways can mechanistically vary , the ability of organisms to perform homologous recombination is universally conserved across all domains of life . Based on the similarity of their amino acid sequences , homologs of a number of proteins can be found in multiple domains of life indicating that they evolved... |
RecA recombinase family members are found in almost all organisms with RecA in bacteria , Rad51 and DMC1 in eukaryotes , RadA in archaea , and UvsX in T4 phage .
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Related single stranded binding proteins that are important for homologous recombination , and many other processes , are also found in all domains of life .
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Rad54 , Mre11 , Rad50 , and a number of other proteins are also found in both archaea and eukaryotes .
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= = = The RecA Recombinase Family = = =
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The proteins of the RecA recombinase family of proteins are thought to be descended from a common ancestral recombinase . The RecA recombinase family contains RecA protein from bacteria , the Rad51 and Dmc1 proteins from eukaryotes , and RadA from archaea , and the recombinase paralog proteins . Studies modeling the e... |
The proteins generally share a long conserved region known as the RecA / Rad51 domain . Within this protein domain are two sequence motifs , Walker A motif and Walker B motif . The Walker A and B motifs allow members of the RecA / Rad51 protein family to engage in ATP binding and ATP hydrolysis .
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= = = Meiosis specific proteins = = =
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The discovery of Dmc1 in several species of Giardia , one of the earliest protists to diverge as a eukaryote , suggests that meiotic homologous recombination — and thus meiosis itself — emerged very early in eukaryotic evolution . In addition to research on Dmc1 , studies on the Spo11 protein have provided information... |
= = Technological applications = =
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= = = Gene targeting = = =
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Many methods for introducing DNA sequences into organisms to create recombinant DNA and genetically modified organisms use the process of homologous recombination . Also called gene targeting , the method is especially common in yeast and mouse genetics . The gene targeting method in knockout mice uses mouse embryonic... |
Advances in gene targeting technologies which hijack the homologous recombination mechanics of cells are now leading to the development of a new wave of more accurate , isogenic human disease models . These engineered human cell models are thought to more accurately reflect the genetics of human diseases than their mo... |
= = = Protein engineering = = =
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Protein engineering with homologous recombination develops chimeric proteins by swapping fragments between two parental proteins . These techniques exploit the fact that recombination can introduce a high degree of sequence diversity while preserving a protein 's ability to fold into its tertiary structure , or three ... |
Techniques that rely on homologous recombination have been used to engineer new proteins . In a study published in 2007 , researchers were able to create chimeras of two enzymes involved in the biosynthesis of isoprenoids , a diverse class of compounds including hormones , visual pigments and certain pheromones . The ... |
= = = Cancer therapy = = =
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Cancer cells with BRCA mutations have deficiencies in homologous recombination , and drugs to exploit those deficiencies have been developed and used successfully in clinical trials . Olaparib , a PARP1 inhibitor , shrunk or stopped the growth of tumors from breast , ovarian and prostate cancers caused by mutations in... |
= Ronnie Mann =
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Ronnie Mann ( born 12 October 1986 ) is an English professional mixed martial artist who competes in the featherweight division . A professional MMA competitor since 2003 , Mann has mostly fought in England and Japan .
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Mann is a veteran of the former top English organisation Cage Rage Championships and was a quarter @-@ finalist in the Sengoku Featherweight Grand Prix in 2009 , losing to Hatsu Hioki . Mann is also the current Shark Fights Featherweight champion , after defeating Doug Evans in September 2010 .
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= = Mixed martial arts career = =
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= = = Background and early career = = =
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Mann grew up in Cheltenham , England . Mann also idolised Marco Ruas and Royce Gracie as a youngster after being introduced to the Ultimate Fighting Championship . Mann began taking Muay Thai lessons at the age of 11 and participated in jiu @-@ jitsu and kickboxing tournaments at the age of 13 . Mann competed in his f... |
= = = Domestic prominence = = =
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In mid @-@ 2006 , Mann signed with top domestic organisation , Cage Rage and made his promotional debut at the Cage Rage : Contenders 1 event against Ashleigh Grimshaw . Mann later stated that the fight was one of his toughest , especially after being hit with an early low blow . The organisation , at the time , adopt... |
Mann later joined the Cage Gladiators promotion in England and made his promotional debut at Cage Gladiators 2 , against Denas Banevicius , winning via submission ( strikes ) at 1 : 42 of the first round . Three months later , Mann returned at Cage Gladiators 3 , defeating Chris Freeborn via submission ( triangle chok... |
At Cage Rage 20 , in a rematch with Ashleigh Grimshaw , whom Mann had earlier drawn with , Mann controlled the stand @-@ up and the top position on the floor . Towards the end of the fight , Grimshaw attempted a comeback , utilising ground @-@ and @-@ pound offense , though Mann was declared the winner via unanimous d... |
Mann 's next fight ( and third in the Cage Rage organisation ) was against top domestic prospect , Robbie Olivier . The fight saw both fighters neutralise the other 's ground game . In the stand @-@ up , Mann was regarded as being unusually tentative , which gave Olivier the opportunity to take him to the floor , wher... |
At Cage Rage 24 , Mann faced Jordan Miller , who took the fight at short notice . Mann was able to take Miller down almost immediately in the fight and took a rear naked choke . Mann dominated from that point and soon after , transitioned to a triangle choke after just 53 seconds of the first round .
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After this , Cage Rage became defunct and Mann re @-@ joined Cage Gladiators , immediately competing against Frederic Fernandez for the Cage Gladiators World Featherweight Championship at the Cage Gladiators 6 event . Mann was able to utilise his wrestling skills again , dominating the takedowns , neutralising his opp... |
Mann was then scheduled to face future World Extreme Cagefighting standout Brad Pickett , though the fight was later cancelled after Pickett suffered a broken arm defending a high kick .
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Mann instead took a fight in Croatia , defeating Ivica Djebic via TKO ( injury ) . Returning to Cage Gladiators at the Cage Gladiators 8 event , Mann defeated Steve McCombe via submission ( choke ) in the first round .
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= = = Sengoku = = =
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Mann then signed with Sengoku Raiden Championship in Japan , to participate in their Featherweight Grand Prix . In the opening round , Mann faced Tetsuya Yamada and defeated him via unanimous decision ( 30 – 29 , 30 – 29 , 30 – 29 ) . During the first round of the fight , Mann was able to land powerful punches , befor... |
In the quarter finals of the tournament , Mann faced early tournament favourite , Hatsu Hioki who had previously defeated World Extreme Cagefighting veteran Chris Manuel . Mann weighed in at 142 @.@ 6 lbs , whilst Hioki , who was unbeaten in his last seven fights , weighed in at 143 @.@ 3 lbs . Mann stated that " [ I ... |
During the fight , Mann was able to land several successful punches , before Hioki took Mann down with a trip , where he was able to land knees and execute a D 'arce choke . After scrambling to avoid an armbar attempt , Mann fell to a triangle choke , tapping out at 3 : 09 of the first round . After the fight , Mann s... |
After his elimination from the Featherweight Grand Prix , Mann competed in his third fight in Sengoku against Shigeki Osawa , who Sherdog labelled a talented young prospect . After three rounds , Mann was victorious , via unanimous decision .
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= = = Move to North America = = =
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Mann still had one more fight left on his Sengoku contract and also expressed a desire to join World Extreme Cagefighting and eventually fight Featherweight Champion Jose Aldo .
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Despite his contract with Sengoku , Mann went on to make his North American debut against Doug Evans on 11 September 2010 at Shark Fights 13 . The bout saw Mann hit Evans with multiple combinations and low kicks , before utilising a flying knee . Evans counter @-@ attacked with takedowns , which he kept up into the fi... |
= = = Bellator Fighting Championships = = =
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On 17 February , it was announced Mann had signed with Bellator Fighting Championships . He had his first fight for the promotion against Josh Arocho at Bellator 42 . Mann was able to dominate the fight with superior wrestling and won the fight via unanimous decision ( 30 @-@ 25 , 30 @-@ 27 , 30 @-@ 27 ) .
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That win earned Mann a place in the Bellator 2011 Summer Series Featherweight Tournament where he faced Adam Schindler at Bellator 46 in his quarter final match @-@ up . Mann stuffed all attempts from the wrestler to take the fight to the ground before he scored a stunning first round KO win with a right uppercut left... |
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