| rdfs:comment
| - Genes órfãos, os genes que estão presentes em apenas uma espécie ou em um grupo de espécies intimamente relacionadas, são regiões codificadoras de proteínas que não possuem homólogo reconhecível em espécies relacionadas à distância. Uma fração substancial de regiões codificadoras em qualquer genoma sequenciado consiste em genes órfãos, mas o significado evolutivo e funcional dos genes órfãos não é compreendido. (pt)
- Orfaj genoj (ankaŭ nomataj "ORFuloj" precipe en primikroba literaturo) estas genoj sen mezureblaj homologoj en aliaj genlinioj. Orfoj estas subaro de taksonomie restriktitaj genoj (TRG), kiuj estas unikaj al specifa taksonomia nivelo (ekz. planto-specifa). Kontraste al neorfaj TRG-oj, orfoj estas kutime konsiderataj unikaj al tre mallarĝa taksono, ĝenerale specio. (eo)
- Orphan genes, ORFans, or taxonomically restricted genes (TRGs) are genes that lack a detectable homologue outside of a given species or lineage. Most genes have known homologues. Two genes are homologous when they share an evolutionary history, and the study of groups of homologous genes allows for an understanding of their evolutionary history and divergence. Common mechanisms that have been uncovered as sources for new genes through studies of homologues include gene duplication, exon shuffling, gene fusion and fission, etc. Studying the origins of a gene becomes more difficult when there is no evident homologue. The discovery that about 10% or more of the genes of the average microbial species is constituted by orphan genes raises questions about the evolutionary origins of different sp (en)
- Гены-сироты (англ. Orphan gene или ORFans, главным образом, в литературе по микробиологии) — это гены без обнаруженных гомологов в других . Сироты — подгруппа (TRG), которые являются уникальными для определённого таксономического уровня (например, для конкретного растения). В отличие от несиротных TRG, сироты обычно считаются уникальными для очень узкого таксона, в основном вида. (ru)
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| has abstract
| - Orfaj genoj (ankaŭ nomataj "ORFuloj" precipe en primikroba literaturo) estas genoj sen mezureblaj homologoj en aliaj genlinioj. Orfoj estas subaro de taksonomie restriktitaj genoj (TRG), kiuj estas unikaj al specifa taksonomia nivelo (ekz. planto-specifa). Kontraste al neorfaj TRG-oj, orfoj estas kutime konsiderataj unikaj al tre mallarĝa taksono, ĝenerale specio. La klasika modelo de evoluo baziĝas sur multobligo, rearanĝo kaj mutacio de genoj kun la ideo de komuna deveno. Orfaj genoj diferencas per tio, ke ili estas genliniaj-specifaj kun nenia konata historio de komuna duobligo kaj rearanĝo ekster iliaj specifaj specioj aŭ klado. Orfaj genoj povas estiĝi per diversaj mekanismoj, kiel horizontala transdono de genoj, multobligo kaj rapida diverĝo, kaj ekapero de novgeno el nekodigita sinsekvo. Ĉi tiuj procezoj povas agi kun malsamaj rapidecoj ĉe insektoj, primatoj kaj plantoj. Malgraŭ ilia relative antaŭnelonga origino, orfaj genoj povas kodi funkcie gravajn proteinojn. (eo)
- Orphan genes, ORFans, or taxonomically restricted genes (TRGs) are genes that lack a detectable homologue outside of a given species or lineage. Most genes have known homologues. Two genes are homologous when they share an evolutionary history, and the study of groups of homologous genes allows for an understanding of their evolutionary history and divergence. Common mechanisms that have been uncovered as sources for new genes through studies of homologues include gene duplication, exon shuffling, gene fusion and fission, etc. Studying the origins of a gene becomes more difficult when there is no evident homologue. The discovery that about 10% or more of the genes of the average microbial species is constituted by orphan genes raises questions about the evolutionary origins of different species as well as how to study and uncover the evolutionary origins of orphan genes. In some cases, a gene can be classified as an orphan gene due to undersampling of the existing genome space. While it is possible that homologues exist for a given gene, that gene will still be classified as an orphan if the organisms harbouring homologues have not yet been discovered and had their genomes sequenced and properly annotated. For example, one study of orphan genes across 119 archaeal and bacterial genomes could identify that at least 56% were recently acquired from integrative elements (or mobile genetic elements) from non-cellular sources such as viruses and plasmids that remain to be explored and characterized, and another 7% arise through horizontal gene transfer from distant cellular sources (with an unknown proportion of the remaining 37% potentially coming from still unknown families of integrative elements). In other cases, limitations in computational methods for detecting homologues may result in missed homologous sequences and thus classification of a gene as an orphan. Homology detection failure appears to account for the majority, but not all orphan genes. In other cases, homology between genes may go undetected due to rapid evolution and divergence of one or both of these genes from each other to the point where they do not meet the criteria used to classify genes as evidently homologous by computational methods. One analysis suggests that divergence accounts for a third of orphan gene identifications in eukaryotes. When homologous genes exist but are simply undetected, the emergence of these orphan genes can be explained by well-characterized phenomena such as genomic recombination, exon shuffling, gene duplication and divergence, etc. Orphan genes may also simply lack true homologues and in such cases have an independent origins via de novo gene birth, which tends to be a more recent event. These processes may act at different rates in insects, primates, and plants. Despite their relatively recent origin, orphan genes may encode functionally important proteins. Characteristics of orphan genes include AT richness, relatively recent origins, taxonomic restriction to a single genome, elevated evolution rates, and shorter sequences. Some approaches characterize all microbial genes as part of one of two classes of genes. One class is characterized by conservation or partial conservation across lineages, whereas the other (represented by orphan genes) is characterized by evolutionarily instantaneous rates of gene turnover/replacement with a negligible effect on fitness when such genes are either gained or lost. These orphan genes primarily derive from mobile genetic elements and tend to be 'passively selfish', often devoid of cellular functions (which is why they experience little selective pressure in their gain or loss from genomes) but persist in the biosphere due to their transient movement across genomes. (en)
- Гены-сироты (англ. Orphan gene или ORFans, главным образом, в литературе по микробиологии) — это гены без обнаруженных гомологов в других . Сироты — подгруппа (TRG), которые являются уникальными для определённого таксономического уровня (например, для конкретного растения). В отличие от несиротных TRG, сироты обычно считаются уникальными для очень узкого таксона, в основном вида. Классическая модель эволюции базируется на дупликации, перестройке и мутации генов с идеей общего происхождения. Гены-сироты отличаются тем, что они специфичны по происхождению без известной истории общей дупликации и перестановки вне их специфических видов или клады. Гены-сироты могут возникать с помощью различных механизмов, таких как горизонтальный перенос генов, дупликация и быстрая дивергенция, а также из некодирующей последовательности. Эти процессы могут действовать с разной скоростью у насекомых, приматов и растений. Несмотря на их относительно недавнее происхождение, гены-сироты могут кодировать функционально важные белки. (ru)
- Genes órfãos, os genes que estão presentes em apenas uma espécie ou em um grupo de espécies intimamente relacionadas, são regiões codificadoras de proteínas que não possuem homólogo reconhecível em espécies relacionadas à distância. Uma fração substancial de regiões codificadoras em qualquer genoma sequenciado consiste em genes órfãos, mas o significado evolutivo e funcional dos genes órfãos não é compreendido. (pt)
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