WordNet

the 4th letter of the Roman alphabet (同)d
concerned chiefly or only with yourself and your advantage to the exclusion of others; "Selfish men were...trying to make capital for themselves out of the sacred cause of civil rights"- Maria Weston Chapman

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deuteriumの化学記号
(人・言動などが)『利己的な』,自分本位の
deoxyribonucleic acidディオキシリボ核酸

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出典(authority):フリー百科事典『ウィキペディア（Wikipedia）』「2015/07/15 23:53:00」(JST)

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Not to be confused with the book The Selfish Gene.

Selfish DNA is a term for sequences of DNA that sensu stricto have two distinct properties:

the DNA sequence spreads by forming additional copies of itself within the genome; and
it makes no specific contribution to the reproductive success of its host organism. (It might or might not have significant deleterious effects.)

In his 1976 book The Selfish Gene^[1] Richard Dawkins suggested the idea of selfish DNA in reaction to the then fairly new revelation of the large proportion of noncoding DNA in eukaryotic genomes. In 1980, two articles in the journal Nature expanded and discussed the concept.^[2]^[3] According to one of these articles:

The theory of natural selection, in its more general formulation, deals with the competition between replicating entities. It shows that, in such a competition, the more efficient replicators increase in number at the expense of their less efficient competitors. After a sufficient time, only the most efficient replicators survive.
— L.E. Orgel & F.H.C. Crick, Selfish DNA: the ultimate parasite.^[3]

In the purest forms of the concepts, units of genetically functional DNA might be viewed as "replicating entities" that effect their replication by manipulating the physiological activities of the cell that they control; in contrast, units of selfish DNA affect their replication by exploiting existing DNA and DNA-manipulating mechanisms in the cell, notionally without significantly affecting the fitness of the organism in other respects.

Irrespective of the strict definition of selfish DNA, there is no sharp, definitive boundary between the concepts of selfish DNA and genetically functional DNA. Often it also is difficult to establish whether a unit of noncoding DNA is functionally important or not, and if important, in what way. What is more, it is not always easy to distinguish between some instances of selfish DNA and some types of viruses.

Examples

Transposons copy themselves to different loci inside the genome. These elements constitute a large fraction of eukaryotic genome sizes (C-values): about 45% of the human genome is composed of transposons and their defunct remnants.

Homing endonuclease genes (HEGs) cleave DNA at its own site on the homologous chromosome, triggering the DNA double-stranded break repair system, which "repairs" the break by copying the HEG onto the homologous chromosome. HEGs have been characterized in yeast, and can only survive by passing between multiple isolated populations or species.

Supernumerary B chromosomes are essential chromosomes that are transmitted in higher-than-expected frequencies, which leads to their accumulation in progenies.

Notes and references

^ Dawkins, Richard R. (1976). The Selfish Gene. New York: Oxford University Press. ISBN 978-0-198-57519-1. OCLC 2681149.
^ Doolittle WF, Sapienza C (1980). "Selfish genes, the phenotype paradigm and genome evolution". Nature 284 (5757): 601–603. doi:10.1038/284601a0. PMID 6245369.
^ ^a ^b Orgel LE, Crick FHC (1980). "Selfish DNA: the ultimate parasite". Nature 284 (5757): 604–607. doi:10.1038/284604a0. PMID 7366731.

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English Journal

Cofactor analogue-induced chemical reactivation of endonuclease activity in a DNA cleavage/methylation deficient TspGWI N473A variant in the NPPY motif.

Zylicz-Stachula A1, Jeżewska-Frąckowiak J, Skowron PM.Author information 1Department of Molecular Biotechnology, Institute for Environmental and Human Health Protection, Faculty of Chemistry, University of Gdansk, Wita Stwosza 63, 80-952, Gdansk, Poland, a.zylicz-stachula@ug.edu.pl.AbstractWe reported previously that TspGWI, a prototype enzyme of a new Thermus sp. family of restriction endonucleases-methyltransferases (REases-MTases), undergoes the novel phenomenon of sinefungin (SIN)-caused specificity transition. Here we investigated mutant TspGWI N473A, containing a single amino acid (aa) substitution in the NPPY motif of the MTase. Even though the aa substitution is located within the MTase polypeptide segment, DNA cleavage and modification are almost completely abolished, indicating that the REase and MTase are intertwined. Remarkably, the TspGWI N473A REase functionality can be completely reconstituted by the addition of SIN. We hypothesize that SIN binds specifically to the enzyme and restores the DNA cleavage-competent protein tertiary structure. This indicates the significant role of allosteric effectors in DNA cleavage in Thermus sp. enzymes. This is the first case of REase mutation suppression by an S-adenosylmethionine (SAM) cofactor analogue. Moreover, the TspGWI N473A clone strongly affects E. coli division control, acting as a 'selfish gene'. The mutant lacks the competing MTase activity and therefore might be useful for applications in DNA manipulation. Here we present a case study of a novel strategy for REase activity/specificity alteration by a single aa substitution, based on the bioinformatic analysis of active motif locations, combining (a) aa sequence engineering (b) the alteration of protein enzymatic properties, and (c) the use of cofactor-analogue cleavage reconstitution and stimulation.
Molecular biology reports.Mol Biol Rep.2014 Apr;41(4):2313-23. doi: 10.1007/s11033-014-3085-x. Epub 2014 Jan 19.
We reported previously that TspGWI, a prototype enzyme of a new Thermus sp. family of restriction endonucleases-methyltransferases (REases-MTases), undergoes the novel phenomenon of sinefungin (SIN)-caused specificity transition. Here we investigated mutant TspGWI N473A, containing a single amino ac
PMID 24442320

Geographic variation within a tandemly repeated mitochondrial DNA D-loop region of a North American freshwater fish, Pylodictis olivaris.

Padhi A.Author information Department of Biological Sciences, University of Tulsa, 800 S. Tucker Dr., OK 74104, USA. Electronic address: abinash74@gmail.com.AbstractThe present study reports the distribution of a 35-bp mitochondrial DNA (mtDNA) D-loop tandemly repeated sequence in the populations of a North American freshwater catfish, Pylodictis olivaris, and the important role of a past geological event in the phylogeographic pattern of this species. A total of 330 individuals of flathead catfish, representing 34 drainages throughout the species' native range in the United States, were collected. While more than 70% of individuals sampled from the Southeastern Gulf Coast drainages were characterized by the presence of a 35-bp mtDNA D-loop tandem repeat proximal to the 5' end, more than 95% of samples from the Mississippi River and its tributaries, as well as from the drainages of the Southwest Gulf Coast region, lack this tandem repeat. Concomitantly, phylogenetic analyses revealed the existence of two distinct matrilineal lineages (lineage I and II) of P. olivaris, which were estimated to have diverged from a common ancestor sometime between 0.70 and 2.05myr ago. While one lineage is comprised of samples from the Mississippi River and its tributaries and rivers draining to the Southwest Gulf Coast, the other lineage is comprised of samples from the Southeastern Gulf Coast drainages. Each lineage also has two sub-lineages, which also showed geographic specificity.
Gene.Gene.2014 Mar 15;538(1):63-8. doi: 10.1016/j.gene.2014.01.020. Epub 2014 Jan 15.
The present study reports the distribution of a 35-bp mitochondrial DNA (mtDNA) D-loop tandemly repeated sequence in the populations of a North American freshwater catfish, Pylodictis olivaris, and the important role of a past geological event in the phylogeographic pattern of this species. A total
PMID 24440244