• Some classes of introns can act as ribozymes. (jove.com)
  • Recently, genetic analyses performed in a group II intron and the yeast nuclear actin gene suggested that non Watson-Crick interactions between intron boundaries are important for the second splicing step efficiency in both classes of introns. (unboundmedicine.com)
  • In contrast, the mitochondrial genomes of vertebrates are entirely devoid of introns, while those of eukaryotic microorganisms may contain many introns. (wikipedia.org)
  • Margaret H. Armstrong , Edward L. Braun , and Rebecca T. Kimball "Phylogenetic Utility of Avian Ovomucoid Intron G: A Comparison of Nuclear and Mitochondrial Phylogenies in Galliformes," The Auk 118(3), 799-804, (1 July 2001). (bioone.org)
  • Comparison of nuclear-encoded cytoplasmic ribosomal proteins and mitochondrial ribosomal proteins showed that intron positions were conserved (Yoshihama et al. (bartleby.com)
  • TTC triplet in the first intron of the FXN gene, encoding the essential mitochondrial protein frataxin. (frontiersin.org)
  • TTC triplet repeat expansion in an intron of the nuclear FXN gene, which encodes the essential mitochondrial protein frataxin ( 1 ). (frontiersin.org)
  • 1998). Population structure of nuclear and mitochondrial DNA variation among humpback whales in the North Pacific . (oregonstate.edu)
  • Using 36 genetic markers (29 newly developed anonymous nuclear loci, six introns and one from mitochondrial DNA, amounting to over 15 kb per individual), we studied population structure and demographic history of the red-backed fairy wren Malurus melanocephalus , a small passerine distributed in the northern and eastern part of Australia across the Carpentarian barrier. (bioone.org)
  • total number of SNPs = 1395), and neither nuclear nor mitochondrial gene trees showed evidence of reciprocal monophyly among Cape York (CY), Eastern Forest (EF), and Top End (TE) populations. (bioone.org)
  • Genome analysis reveals interplay between 5'UTR introns and nuclear mRNA export for secretory and mitochondrial genes. (umassmed.edu)
  • [ 13 ] The mitochondrial genome is remarkably concise, containing little noncoding capacity and no introns. (medscape.com)
  • Located within the mitochondrial matrix, and lacking the efficient repair mechanisms available to nuclear DNA, mtDNA has a relatively high rate of mutation. (medscape.com)
  • Although introns are sometimes called intervening sequences, the term "intervening sequence" can refer to any of several families of internal nucleic acid sequences that are not present in the final gene product, including inteins, untranslated regions (UTR), and nucleotides removed by RNA editing, in addition to introns. (wikipedia.org)
  • The regulation of expression of X-box-binding protein-1 (XBP1), a transcriptional factor, involves an unconventional mRNA splicing that removes the 26 nucleotides intron. (mdpi.com)
  • Group one and two introns are large ribozymes that are several hundred nucleotides long and are found in fungal and plant mitochondria, chloroplasts, bacteriophages, and eukaryotic viruses. (jove.com)
  • Many introns in Drosophila and other invertebrates are less than 80 nucleotides in length, too small to be recognized by the vertebrate splicing machinery. (umd.edu)
  • As observed with the 74 nucleotide second intron of the Drosophila white gene, the wild-type myosin intron is accurately spliced in a homologous extract, and increasing the size by 16 nucleotides both eliminates splicing in the Drosophila extract and allows accurate splicing in the human extract. (umd.edu)
  • we noted that a naturally larger (150 nucleotide) intron from the ftz gene is efficiently spliced in Kc cell extracts that do not splice enlarged introns (of 84, 90, 150 or 350 nucleotides) derived from the 74 nucleotide white intron. (umd.edu)
  • Here, we have exploited that observation, using a series of hybrid introns to show that a region of 46 nucleotides at the 3' end of the white intron is sufficient to confer the species-specific size effect. (umd.edu)
  • These results demonstrate that the interaction between the first and last intron nucleotides is a conserved feature of nuclear pre-mRNA splicing in yeast and is involved in the mechanism of 3' splice site selection. (unboundmedicine.com)
  • We identify increased intron retention (IR) as a dominant feature of the splicing programme during early neural differentiation. (crick.ac.uk)
  • An intron is any nucleotide sequence within a gene that is not expressed or operative in the final RNA product. (wikipedia.org)
  • In addition, they contain a branch point, a particular nucleotide sequence near the 3' end of the intron that becomes covalently linked to the 5' end of the intron during the splicing process, generating a branched (lariat) intron. (wikipedia.org)
  • Introns are nucleotide sequences universal amongst the Eukarya domain. (bartleby.com)
  • Here we present additional results with the 68 nucleotide fifth intron of the Drosophila myosin heavy chain gene. (umd.edu)
  • In contrast to previous results, however, an upstream cryptic 5' splice site is activated when the wild-type myosin intron is tested in a human HeLa cell nuclear extract, resulting in the removal of a 98 nucleotide intron. (umd.edu)
  • Moreover, the natural 3' splice site could be reactivated by a G to C substitution of the last intron nucleotide. (unboundmedicine.com)
  • Length polymorphisms of the intron amplification (EPIC-PCR) were analysed on 24 systems, only five of which gave easily interpretable and polymorphic patterns, corresponding to 11 presumptive loci. (hal.science)
  • According to the multidimensional statistics, the genetic analysis demonstrated the existence of four clearly independent geographical taxa included in O. bidens, characterized by unambiguous diagnostic intron loci. (hal.science)
  • We performed large-scale sequencing of 600 rice accessions with high diversity, which were collected in 1980 and 2007, using ten unlinked nuclear loci. (springer.com)
  • Splicing of all intron-containing RNA molecules is superficially similar, as described above. (wikipedia.org)
  • However, different types of introns were identified through the examination of intron structure by DNA sequence analysis, together with genetic and biochemical analysis of RNA splicing reactions. (wikipedia.org)
  • Transfer RNA introns that depend upon proteins for removal occur at a specific location within the anticodon loop of unspliced tRNA precursors, and are removed by a tRNA splicing endonuclease. (wikipedia.org)
  • We propose that the nuclear envelope's incipient function was to allow mRNA splicing, which is slow, to go to completion so that translation, which is fast, would occur only on mRNA with intact reading frames. (nature.com)
  • Cech, T. R. The generality of self-splicing RNA: Relationship to nuclear mRNA splicing. (nature.com)
  • Ferat, J.-L. & Michel, F. Group II self splicing introns in bacteria. (nature.com)
  • We then sought to address specificity of MIG expression, minor intron retention, and alternative splicing (AS) across mouse and human tissues. (biomedcentral.com)
  • Here we show that minor intron splicing and AS across minor introns is a highly organised process that might be regulated in coordination with the major spliceosome in a tissue-specific manner. (biomedcentral.com)
  • Splicing of introns is required for the expression of most eukaryotic genes. (biomedcentral.com)
  • Regardless, mis-splicing of these few minor introns can have detrimental consequences, as highlighted by diseases caused by mutation in minor spliceosome components. (biomedcentral.com)
  • The spliceosome complex, composed of at least 170 proteins and several small nuclear RNAs (snRNAs), is the key structure responsible for splicing in eukaryotes 10 . (nature.com)
  • Localization of sequences required for size-specific splicing of a small Drosophila intron in vitro. (umd.edu)
  • Comparison of nuclear splicing extracts from human HeLa and Drosophila Kc cells has revealed species-specificity, consistent with the observed size differences. (umd.edu)
  • At least two sequence elements within this region, yet distinct from previously described branchpoint and pyrimidine tract signals, are required for efficient splicing of small hybrid introns in vitro. (umd.edu)
  • The splicing of group II and nuclear pre-mRNAs introns occurs via a similar splicing pathway and some of the RNA-RNA interactions involved in these splicing reactions show structural similarities. (unboundmedicine.com)
  • This subfamily corresponds to the RRM of U11/U12-35K, also termed protein HM-1, or U1 snRNP-binding protein homolog, and is one of the components of the U11/U12 snRNP, which is a subunit of the minor (U12-dependent) spliceosome required for splicing U12-type nuclear pre-mRNA introns. (nih.gov)
  • The interspersed introns can be removed through a large multiprotein splicing complex (the spliceosome) to yield the mature mRNA. (researchsquare.com)
  • Belongs also to the minor U12-dependent spliceosome, which is involved in the splicing of rare class of nuclear pre-mRNA intron. (thermofisher.com)
  • The primers for trnL intron and trnL-trnF intergenic spacer regions were described in Taberlet et al. (uni-goettingen.de)
  • Phylogeny of Smelowskia and related genera (Brassicaceae) based on nuclear ITS DNA and chloroplast trnL intron DNA sequences. (wikimedia.org)
  • The non-intron sequences that become joined by this RNA processing to form the mature RNA are called exons. (wikipedia.org)
  • must be replaced by that of a transcription unit containing regions which will be lost from the mature messenger - which I suggest we call introns (for intragenic regions) - alternating with regions which will be expressed - exons. (wikipedia.org)
  • Nuclear pre-mRNA introns (spliceosomal introns) are characterized by specific intron sequences located at the boundaries between introns and exons. (wikipedia.org)
  • Nuclear pre-mRNA introns are often much longer than their surrounding exons. (wikipedia.org)
  • In multicellular organisms, a pre-mRNA is composed of exons intervened with introns. (researchsquare.com)
  • We then analyzed the RNAseq data from eleven different mouse tissues, which revealed tissue-specific MIG expression and minor intron retention. (biomedcentral.com)
  • Moreover, like the major introns, we found that these AS events were more prevalent in long minor introns, while retention was favoured in shorter introns. (biomedcentral.com)
  • The biological functions of intron retention (IR) and nonsense-mediated mRNA decay (NMD) in filamentous fungi is lack of study, let alone their roles in cellulase biosynthesis. (researchsquare.com)
  • Our results provide better understanding on intron retention, the NMD pathway, and cellulase production mechanism in filamentous fungi. (researchsquare.com)
  • In intron retention (IR), introns that are supposed to be spliced appear in mature mRNA and subsequently participate in the translation process. (researchsquare.com)
  • Introns were first discovered in protein-coding genes of adenovirus, and were subsequently identified in genes encoding transfer RNA and ribosomal RNA genes. (wikipedia.org)
  • Phylogenetic relationships in the tribes Schizopetaleae and Thelypodieae (Brassicaceae) based on nuclear ribosomal ITS region and plastid ndh F DNA sequences. (wikimedia.org)
  • Closing the gaps: phylogenetic relationships in the Brassicaceae based on DNA sequence data of nuclear ribosomal ITS region. (wikimedia.org)
  • Phylogeny of Isatis (Brassicaceae) and allied genera based on ITS sequences of nuclear ribosomal DNA and morphological characters. (wikimedia.org)
  • Specific tertiary structure types are observed for transfer RNA (tRNA), ribosomal RNA (rRNA), small nuclear RNA (snRNA), certain introns, and ribozymes. (biosyn.com)
  • Apart from these three short conserved elements, nuclear pre-mRNA intron sequences are highly variable. (wikipedia.org)
  • Introns are categorized into five distinct classes - nuclear mRNA, nuclear tRNA, archaeal, group one, and group two introns. (jove.com)
  • For example, introns are extremely common within the nuclear genome of jawed vertebrates (e.g. humans, mice, and pufferfish (fugu)), where protein-coding genes almost always contain multiple introns, while introns are rare within the nuclear genes of some eukaryotic microorganisms, for example baker's/brewer's yeast (Saccharomyces cerevisiae). (wikipedia.org)
  • Hence, the proportion of introns in the LECA genome is considerably greater than in contemporary eukaryotic lineages, excluding some vertebrates (Figure.1). (bartleby.com)
  • Therefore, we first wanted to revisit the classification of minor introns in light of the most recent reference genome. (biomedcentral.com)
  • It possesses two differentiated forms of its nuclear genome: a globally repressed, diploid germline or micronuclear genome, and a polyploid, site-specifically fragmented somatic or macronuclear genome. (bioone.org)
  • This presentation also reviews unique tools generated by nuclear dimorphism that are being used for genetically and physically mapping the Tetrahymena genome. (bioone.org)
  • The term intron refers to both the DNA sequence within a gene and the corresponding RNA sequence in RNA transcripts. (wikipedia.org)
  • HIV-1 Rev mediates the nuclear export of intron-containing viral RNA transcripts and is essential for viral replication. (nih.gov)
  • Only exonic reads are shown for RNAs in cells, whereas exonic and intronic reads are combined for nuclear transcripts. (elifesciences.org)
  • They can self-splice without the help of any proteins, whereas nuclear introns are spliced by the spliceosome, an RNA and protein-containing enzyme complex. (jove.com)
  • The frequency of introns within different genomes is observed to vary widely across the spectrum of biological organisms. (wikipedia.org)
  • Although they possess many valuable roles this does not explain the ubiquity of introns within eukaryotic genomes. (bartleby.com)
  • Introns are rare in Bacteria and Archaea (prokaryotes), but most eukaryotic genes contain multiple splicesomal introns. (wikipedia.org)
  • Introns are now known to occur within a wide variety of genes throughout organisms, bacteria, and viruses within all of the biological kingdoms. (wikipedia.org)
  • Given that the minor spliceosome is ubiquitously expressed, we hypothesized that these restricted phenotypes might be caused by the tissue-specific regulation of the minor spliceosome targets, i.e. minor intron-containing genes (MIGs). (biomedcentral.com)
  • In these minor intron-containing genes (MIGs), the majority of introns are usually spliced by the major spliceosome, with only one or two introns being spliced by the minor spliceosome. (biomedcentral.com)
  • It may facilitate 5' splice site recognition in the minor spliceosome and play a role in exon bridging, interacting with components of the major spliceosome bound to the pyrimidine tract of an upstream U2-type intron. (nih.gov)
  • The word intron is derived from the term intragenic region, i.e., a region inside a gene. (wikipedia.org)
  • A particularly extreme case is the Drosophila dhc7 gene containing a ≥3.6 megabase (Mb) intron, which takes roughly three days to transcribe. (wikipedia.org)
  • On the other extreme, a 2015 study suggests that the shortest known metazoan intron length is 30 base pairs (bp) belonging to the human MST1L gene. (wikipedia.org)
  • Introns are found in the genes of most organisms and many viruses and they can be located in both protein-coding genes and genes that function as RNA (noncoding genes). (wikipedia.org)
  • The fact that genes were split or interrupted by introns was discovered independently in 1977 by Phillip Allen Sharp and Richard J. Roberts, for which they shared the Nobel Prize in Physiology or Medicine in 1993. (wikipedia.org)
  • Molecular phylogeny of tribe Dipterocarpeae (family Dipterocarpaceae) based on sequence data of chloroplast and nuclear DNA. (uni-goettingen.de)
  • Many studies have been carried out to resolve the taxonomic relationships of subfamily Dipterocarpoideae based on chloroplast and nuclear DNA. (uni-goettingen.de)
  • Ribozymes were first discovered in 1982 when Tom Cech's laboratory observed Group I introns acting as enzymes. (jove.com)
  • The type I and II introns and bacterial Ribonuclease P are large ribozymes. (jove.com)
  • Cavalier-Smith, T. Intron phylogeny: A new hypothesis. (nature.com)
  • any degree of intron conservation in modern eukaryotes is suggestive of function, despite appearing to exist solely for removal. (bartleby.com)
  • The SFPQ protein binds extensively to its retained intron, exhibits lower nuclear abundance in VCP mutant cultures and is lost from nuclei of MNs in mouse models and human sporadic ALS. (crick.ac.uk)
  • A novel nuclear marker, the avian ovomucoid intron G (OVOG) was sequenced from 19 galliform taxa. (bioone.org)
  • The objective of this study was to analyse the genetic structure of populations of Opsariichthys bidens and to describe its subdivisions, if any, using nuclear markers, to serve as a guideline for stock selection and management in the potential aquaculture of this species. (hal.science)
  • Collectively, we demonstrate SFPQ IR and nuclear loss as molecular hallmarks of familial and sporadic ALS. (crick.ac.uk)
  • This presentation describes how the gifts of nuclear dimorphism are being exploited in the experimental analysis of molecular and cell biology. (bioone.org)
  • We employed position-weight matrices to obtain a comprehensive updated list of minor introns, consisting of 722 mouse and 770 human minor introns. (biomedcentral.com)