Selfish DNA: the ultimate parasite

Orgel, Leslie E.; Crick, Francis

doi:10.1038/284604a0

Cited by 1,909 publications

(1,001 citation statements)

References 18 publications

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“…Hence, biologists frequently model natural selection acting not only on the individual (Darwin 1859(Darwin /1968, but at any level that exhibits variation, differential fitness, and inheritance of fitness-related characters (Lewontin 1970). This may include levels below the individual, such as the case of selfish DNA (Orgel & Crick 1980) which is selected within the genome but which does not directly affect selection at the phenotypic level, or above the individual, as in the case of group selection (Sober & Wilson 1998;Wilson & Sober 1994), species selection (Stanley 1975), or clade selection (Vermeij 1996). We see no difficulty envisaging similar multilevel selection occurring in cultural evolution, negating much of Read's criticism that Darwinian evolution cannot deal with selection operating at the social level, as with kin terminology ("The selection acting on kinship terminologies occurs at the level of structural properties").…”

Section: R34 Cultural Selectionmentioning

confidence: 99%

Towards a unified science of cultural evolution

2006

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We suggest that human culture exhibits key Darwinian evolutionary properties, and argue that the structure of a science of cultural evolution should share fundamental features with the structure of the science of biological evolution. This latter claim is tested by outlining the methods and approaches employed by the principal subdisciplines of evolutionary biology and assessing whether there is an existing or potential corresponding approach to the study of cultural evolution. Existing approaches within anthropology and archaeology demonstrate a good match with the macroevolutionary methods of systematics, paleobiology, and biogeography, whereas mathematical models derived from population genetics have been successfully developed to study cultural microevolution. Much potential exists for experimental simulations and field studies of cultural microevolution, where there are opportunities to borrow further methods and hypotheses from biology. Potential also exists for the cultural equivalent of molecular genetics in "social cognitive neuroscience," although many fundamental issues have yet to be resolved. It is argued that studying culture within a unifying evolutionary framework has the potential to integrate a number of separate disciplines within the social sciences.

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Section: R34 Cultural Selectionmentioning

confidence: 99%

Towards a unified science of cultural evolution

2006

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“…RNA was informational, acted as its own template and was capable of catalysis; it could promote its own perpetuation, either directly or by co-opting other partners along the way. The preferential replication of selfish RNA has defined the evolutionary space for soft-wired organisms ever since 2,9 . In humans, we find that much of the DNA genome has arisen from retrotransposition and that RNA-directed processes impact the read-out of RNA from genes and also rewrite their RNA transcripts.…”

Section: Originsmentioning

confidence: 99%

The four Rs of RNA-directed evolution

Herbert

2003

Nat Genet

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The read-out of genetic information in eukaryotes is not only more complex than previously realized, but also more dynamic. Much of the information is 'soft-wired' , with extensive RNA processing necessary to generate phenotypes 10 . A subset of the RNA, referred to here as coRNA ( Fig. 1), coordinates the read-out of genetic information and reconciles regulatory inputs. For each cell type, the sum of these interactions defines a distinct RNA profile or ribotype 10 . RNA-based processes also facilitate replication of ribotypes in subsequent generations. The flexibility of these programs allows soft-wired organisms to evolve in a more rapid and dynamic way than 'hard-wired' organisms constrained by DNA mutation 10 . Together, the actions of reading, 'riting, 'rithmetic and replication constitute the four Rs of RNA-directed evolution. Here, we describe roles for coRNAs and SATs (Fig. 2) in these events. RNA-directed RNA readoutRNA coregulates the sequence-specific read-out of genetic information from RNA by targeting the evolutionarily conserved machinery of RNA interference (RNAi) 11 and translational repression. RNAi leading to post-transcriptional gene silencing (PTGS) is induced by doublestranded RNA (dsRNA) arising from infection by dsRNA viruses, senseantisense transcription pairs, transcription of inverted repeats and delivery of dsRNAs manufactured in vitro 12 . Both endogenous and exogenous dsRNAs are processed cytoplasmically by RNase III dicer paralogs into small interfering RNAs (siRNAs) that are 21-25 bases long 12,13 . These siRNAs are incorporated into an RNA-induced silencing complex (RISC) that targets any RNA with a sequence complementary to the siRNA 12,14 . The target RNA is cleaved by RISC, which has endonucleolytic and presumed exonucleolytic activity 12,15 . Each cycle results in the destruction of the target RNA and the regeneration of an active RISC 16,17 .In Neurospora crassa 18,19 , plants 20 , Schizosaccharomyces pombe 21 and Caenorhabditis elegans 22 , but not in flies, humans or mouse oocyctes 18,19,23,24 , PTGS can also be initiated by an RNA-dependent RNA polymerase (RdRP) that synthesizes complementary RNA from highly expressed transcripts to generate dsRNA. This process can spread from the 3´ to the 5´ end of the mRNA, leading to progressive silencing of a gene and other mRNAs with exons in common (transitive RNAi) 18,22 . From the evolutionary viewpoint, transitive RNAi favors the generation of new phenotypes, as related genes in species with polyploid genomes will escape cosuppression by sequence divergence, resulting in altered function or expression.The number of dicer paralogs also differs between species. Arabidopsis, which has at least four dicer family members, seems to use different enzymes to defend against viruses and to process endogenously produced dsRNA 13,25 . In humans, mice and worms, there is only one dicer ortholog, suggesting that any pathway-specific functions are guided by ancillary regulatory proteins associated with RISC. These ancillary proteins include me...

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“…Initially, transposable elements and other repeats were suggested to play intrinsic roles in the regulation of gene expression (1,2) but later they were regarded as parasitic or ''junk'' DNA possessing no phenotypic impact. (3,4) Recent evidence, however, indicates that many transposable elements as well as simple-sequence tandem repeats were utilized in evolution to create new regulatory signals in proteincoding and RNA-coding genes. Examples of the association of transcription regulatory motifs with transposable elements have been summarized earlier in many reviews.…”

Section: Introductionmentioning

confidence: 99%

Regulation of mammalian gene expression by retroelements and non‐coding tandem repeats

Tomilin

2008

BioEssays

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Genomes of higher eukaryotes contain abundant non‐coding repeated sequences whose overall biological impact is unclear. They comprise two categories. The first consists of retrotransposon‐derived elements. These are three major families of retroelements (LINEs, SINEs and LTRs). SINEs are clustered in gene‐rich regions and are found in promoters of genes while LINEs are concentrated in gene‐poor regions and are depleted from promoters. The second class consists of non‐coding tandem repeats (satellite DNAs and TTAGGG arrays), which are associated with mammalian centromeres, heterochromatin and telomeres. Terminal TTAGGG arrays are involved in telomere capping and satellite DNAs are located in heterochromatin, which is implicated in transcription silencing by gene repositioning (relocalization). It is unknown whether interstitial TTAGGG sequences, which are present in many vertebrates, have a function. Here, evidence will be presented that retroelements and TTAGGG arrays are involved in regulation of gene expression. Retroelements can provide binding sites for transcription factors and protect promoter CpG islands from repressive chromatin modifications, and may be also involved in nuclear compartmentalization of transcriptionally active and inactive domains. Interstitial telomere‐like sequences can form dynamically maintained three‐dimensional nuclear networks of transcriptionally inactive domains, which may be involved in transcription silencing like classic heterochromatin. BioEssays 30:338–348, 2008. © 2008 Wiley Periodicals, Inc.

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Selfish DNA: the ultimate parasite

Cited by 1,909 publications

References 18 publications

Towards a unified science of cultural evolution

Towards a unified science of cultural evolution

The four Rs of RNA-directed evolution

Regulation of mammalian gene expression by retroelements and non‐coding tandem repeats

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