This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Heteroduplex" – news · newspapers · books · scholar · JSTOR(April 2023) (Learn how and when to remove this message)
A current model of meiotic recombination, initiated by a double-strand break or gap, followed by pairing with a homologous chromosome and strand invasion to initiate the recombinational repair process. Repair of the gap can lead to crossover (CO) or non-crossover (NCO) of the flanking regions. CO recombination is thought to occur by the Double Holliday Junction (DHJ) model, illustrated on the right, above. NCO recombinants are thought to occur primarily by the Synthesis Dependent Strand Annealing (SDSA) model, illustrated on the left, above. Most recombination events appear to be the SDSA type. At various steps of the recombination process, heteroduplex DNA (double-stranded DNA consisting of single strands from each of the two homologous chromosomes) is formed.
A heteroduplex is a double-stranded (duplex) molecule of nucleic acid originated through the genetic recombination of single complementary strands derived from different sources, such as from different homologous chromosomes or even from different organisms.
One such example is the heteroduplex DNA strand formed in hybridization processes, usually for biochemistry-based phylogenetic analyses. Another is the heteroduplexes formed when non-natural analogs of nucleic acids are used to bind with nucleic acids; these heteroduplexes result from performing antisense techniques using single-stranded peptide nucleic acid, 2'-O-methyl phosphorothioate or Morpholino oligos to bind with RNA.
Meiotic recombination can be initiated by a double-strand break (DSB) in DNA. The 5’ ends of the break are degraded, leaving long 3’ overhangs of several hundred nucleotides (see Figure). One of these 3’ single stranded DNA segments then invades a homologous sequence on the homologous chromosome, forming an intermediate which can be repaired through different pathways resulting either in crossovers (CO) or noncrossovers (NCO) as illustrated in the Figure. By one pathway, a structure called a double Holliday junction (DHJ) is formed, leading to the exchange of DNA strands. By the other pathway, referred to as Synthesis-dependent strand annealing (SDSA), there is information exchange but not physical exchange. At various steps of these recombination processes, heteroduplex DNA (double-stranded DNA consisting of single strands from each of the two homologous chromosomes which may or may not be perfectly complementary) is formed. During meiosis non-crossover recombinants occur frequently and these appear to arise mainly by the SDSA pathway.[1][2] Non-crossover recombination events occurring during meiosis likely reflect instances of repair of DNA double-strand damages or other types of DNA damages. When mismatches occur in heteroduplex DNA, the sequence of one strand can be repaired to bind the other strand with perfect complementarity.
During mitosis, the major homologous recombination pathway for repairing DNA double-strand breaks appears to be the SDSA pathway (rather than the DSBR pathway).[1] The SDSA pathway produces non-crossover recombinants (see Figure).
In meiosis, the process of crossing-over occurs between non-sister chromatids, which results in new allelic combinations in the gametes. In crossing-over, a Spo11 enzyme makes staggered nicks in a pair of sister chromatid strands (in a tetrad organization of prophase). Subsequent enzymes trim back the 5' ends of the strand and a protein complex binds to the 3' single-stranded ends. Rad51 protein is recruited and binds in a protein complex to search for a complementary sequence analogous to double-strand-break repair. The filament searches for the homologous chromosome, strand invasion occurs where the new chromosome forms a D-loop over the bottom sister chromatid, then the ends are annealed. This process can yield double Holliday junctions that when cut in a transversal pattern by endonucleases form 2 heteroduplex strand products.
Heteroduplex DNA is also a source of small RNAs (smRNAs), causing post-transcriptional gene silencing.
^ abAndersen SL, Sekelsky J (December 2010). "Meiotic versus mitotic recombination: two different routes for double-strand break repair: the different functions of meiotic versus mitotic DSB repair are reflected in different pathway usage and different outcomes". BioEssays. 32 (12): 1058–1066. doi:10.1002/bies.201000087. PMC 3090628. PMID 20967781.
^Allers T, Lichten M (July 2001). "Differential timing and control of noncrossover and crossover recombination during meiosis". Cell. 106 (1): 47–57. doi:10.1016/s0092-8674(01)00416-0. PMID 11461701. S2CID 1878863.
A heteroduplex is a double-stranded (duplex) molecule of nucleic acid originated through the genetic recombination of single complementary strands derived...
Heteroduplex analysis (HDA) is a method in biochemistry used to detect point mutations in DNA (Deoxyribonucleic acid) since 1992. Heteroduplexes are dsDNA...
Delivery system (no longer commercially available, used a Morpholino-DNA heteroduplex and an ethoxylated polyethylenimine delivery reagent), electroporation...
present. RNA polymerase then starts to synthesize the initial DNA-RNA heteroduplex, with ribonucleotides base-paired to the template DNA strand according...
polymorphism (SNP) detection, single-strand conformation polymorphism (SSCP) heteroduplex analysis, and short tandem repeat (STR) analysis. Resolving DNA fragments...
5’ exonucleases. This process allows 3’ flap ligation, and creates a heteroduplex DNA composed of one edited strand and one unedited strand. The reannealed...
two recombining DNA double helices. After the synapsis event, in the heteroduplex region a process called branch migration begins. In branch migration...
SM (28 November 2007). Sandler S (ed.). "Physical analyses of E. coli heteroduplex recombination products in vivo: on the prevalence of 5' and 3' patches"...
noncrossovers (NCO). At various steps of the recombination process, heteroduplex DNA (double-stranded DNA consisting of single strands from each of the...
genomic DNA) then DNA from a control sample is needed in order to form a heteroduplex which is then recognizable by the nuclease. If the DNA sample is heterogeneous...
crossover. Holliday realized that the proposed pathway would create heteroduplex DNA segments with base mismatches between different versions of a single...
Biographie (in German). Retrieved 27 May 2017. Hiv, Visna Heteroduplex, Gonda, 1985, i Hiv, Visna Heteroduplex, Gonda, 1985, ii Thomar, Ähnlichkeit von Aids und...
pairing where the polymorphism is located. These "mismatches" in the heteroduplex are the basis for the polymorphism detection by DHPLC. Heteroduplexes...
putative target permitting bulges and G:U wobbles in the seed region of the heteroduplex. Lastly, the algorithm has been shown to achieve high signal-to-noise...
detecting genetic differences between parental and progeny strains. Heteroduplex mobility assays can be used to sequence viral genetic material, allowing...
deletion in the antithrombin gene, AT106-108(-6 bp), identified by DNA heteroduplex detection". Genomics. 16 (1): 298–299. doi:10.1006/geno.1993.1184. PMID 8486379...
of MSH3 in endometrial cancer and evidence for its functional role in heteroduplex repair". Nat. Genet. 14 (1): 102–5. doi:10.1038/ng0996-102. PMID 8782829...
Fluorescent Fragments (QMPSF). Newer methods have also been recently proposed: heteroduplex analysis (HDA) by multi-capillary electrophoresis or also dedicated oligonucleotides...
lysines to position the enzyme at the 3'-DNA/5'-RNA terminus of the heteroduplex substrate". J. Biol. Chem. 278 (50): 49860–7. doi:10.1074/jbc.M306543200...
"Evidence for a dual functional role of a conserved histidine in RNA·DNA heteroduplex cleavage by human RNase H1". FEBS Journal. 279 (24): 4492–500. doi:10...
Global Information
