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  1. Article ; Online: Where the minor things are: a pan-eukaryotic survey suggests neutral processes may explain much of minor intron evolution.

    Larue, Graham E / Roy, Scott W

    Nucleic acids research

    2023  Volume 51, Issue 20, Page(s) 10884–10908

    Abstract: Spliceosomal introns are gene segments removed from RNA transcripts by ribonucleoprotein machineries called spliceosomes. In some eukaryotes a second 'minor' spliceosome is responsible for processing a tiny minority of introns. Despite its seemingly ... ...

    Abstract Spliceosomal introns are gene segments removed from RNA transcripts by ribonucleoprotein machineries called spliceosomes. In some eukaryotes a second 'minor' spliceosome is responsible for processing a tiny minority of introns. Despite its seemingly modest role, minor splicing has persisted for roughly 1.5 billion years of eukaryotic evolution. Identifying minor introns in over 3000 eukaryotic genomes, we report diverse evolutionary histories including surprisingly high numbers in some fungi and green algae, repeated loss, as well as general biases in their positional and genic distributions. We estimate that ancestral minor intron densities were comparable to those of vertebrates, suggesting a trend of long-term stasis. Finally, three findings suggest a major role for neutral processes in minor intron evolution. First, highly similar patterns of minor and major intron evolution contrast with both functionalist and deleterious model predictions. Second, observed functional biases among minor intron-containing genes are largely explained by these genes' greater ages. Third, no association of intron splicing with cell proliferation in a minor intron-rich fungus suggests that regulatory roles are lineage-specific and thus cannot offer a general explanation for minor splicing's persistence. These data constitute the most comprehensive view of minor introns and their evolutionary history to date, and provide a foundation for future studies of these remarkable genetic elements.
    MeSH term(s) Animals ; Evolution, Molecular ; Fungi/genetics ; Genome ; Introns ; RNA Splicing/genetics ; Spliceosomes/genetics ; Spliceosomes/metabolism
    Language English
    Publishing date 2023-10-24
    Publishing country England
    Document type Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 186809-3
    ISSN 1362-4962 ; 1362-4954 ; 0301-5610 ; 0305-1048
    ISSN (online) 1362-4962 ; 1362-4954
    ISSN 0301-5610 ; 0305-1048
    DOI 10.1093/nar/gkad797
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  2. Article ; Online: Expansion and transformation of the minor spliceosomal system in the slime mold Physarum polycephalum.

    Larue, Graham E / Eliáš, Marek / Roy, Scott W

    Current biology : CB

    2021  Volume 31, Issue 14, Page(s) 3125–3131.e4

    Abstract: Spliceosomal introns interrupt nuclear genes and are removed from RNA transcripts ("spliced") by machinery called spliceosomes. Although the vast majority of spliceosomal introns are removed by the so-called major (or "U2") spliceosome, diverse ... ...

    Abstract Spliceosomal introns interrupt nuclear genes and are removed from RNA transcripts ("spliced") by machinery called spliceosomes. Although the vast majority of spliceosomal introns are removed by the so-called major (or "U2") spliceosome, diverse eukaryotes also contain a rare second form, the minor ("U12") spliceosome, and associated ("U12-type") introns.
    MeSH term(s) Introns ; Physarum polycephalum/genetics ; RNA Splicing ; RNA, Small Nuclear/genetics ; RNA, Small Nuclear/metabolism ; Spliceosomes/genetics ; Spliceosomes/metabolism
    Chemical Substances RNA, Small Nuclear
    Language English
    Publishing date 2021-05-19
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 1071731-6
    ISSN 1879-0445 ; 0960-9822
    ISSN (online) 1879-0445
    ISSN 0960-9822
    DOI 10.1016/j.cub.2021.04.050
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  3. Article ; Online: Intron-rich dinoflagellate genomes driven by Introner transposable elements of unprecedented diversity.

    Roy, Scott William / Gozashti, Landen / Bowser, Bradley A / Weinstein, Brooke N / Larue, Graham E / Corbett-Detig, Russell

    Current biology : CB

    2022  Volume 33, Issue 1, Page(s) 189–196.e4

    Abstract: Spliceosomal introns, which interrupt nuclear genes, are ubiquitous features of eukaryotic nuclear genes. ...

    Abstract Spliceosomal introns, which interrupt nuclear genes, are ubiquitous features of eukaryotic nuclear genes.
    MeSH term(s) Introns/genetics ; Phylogeny ; DNA Transposable Elements/genetics ; Dinoflagellida/genetics ; Evolution, Molecular ; Spliceosomes/genetics
    Chemical Substances DNA Transposable Elements
    Language English
    Publishing date 2022-12-20
    Publishing country England
    Document type Journal Article ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 1071731-6
    ISSN 1879-0445 ; 0960-9822
    ISSN (online) 1879-0445
    ISSN 0960-9822
    DOI 10.1016/j.cub.2022.11.046
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  4. Article ; Online: Comprehensive database and evolutionary dynamics of U12-type introns.

    Moyer, Devlin C / Larue, Graham E / Hershberger, Courtney E / Roy, Scott W / Padgett, Richard A

    Nucleic acids research

    2020  Volume 48, Issue 13, Page(s) 7066–7078

    Abstract: During nuclear maturation of most eukaryotic pre-messenger RNAs and long non-coding RNAs, introns are removed through the process of RNA splicing. Different classes of introns are excised by the U2-type or the U12-type spliceosomes, large complexes of ... ...

    Abstract During nuclear maturation of most eukaryotic pre-messenger RNAs and long non-coding RNAs, introns are removed through the process of RNA splicing. Different classes of introns are excised by the U2-type or the U12-type spliceosomes, large complexes of small nuclear ribonucleoprotein particles and associated proteins. We created intronIC, a program for assigning intron class to all introns in a given genome, and used it on 24 eukaryotic genomes to create the Intron Annotation and Orthology Database (IAOD). We then used the data in the IAOD to revisit several hypotheses concerning the evolution of the two classes of spliceosomal introns, finding support for the class conversion model explaining the low abundance of U12-type introns in modern genomes.
    MeSH term(s) Animals ; Databases, Genetic ; Evolution, Molecular ; Genome ; Humans ; Introns/genetics ; Phylogeny ; Plants/genetics ; RNA Splicing/genetics ; RNA, Long Noncoding/genetics ; RNA, Small Nuclear/genetics ; Ribonucleoproteins, Small Nuclear/genetics ; Spliceosomes/genetics ; Yeasts/genetics
    Chemical Substances RNA, Long Noncoding ; RNA, Small Nuclear ; Ribonucleoproteins, Small Nuclear
    Language English
    Publishing date 2020-06-02
    Publishing country England
    Document type Dataset ; Journal Article ; Research Support, N.I.H., Extramural ; Research Support, U.S. Gov't, Non-P.H.S.
    ZDB-ID 186809-3
    ISSN 1362-4962 ; 1362-4954 ; 0301-5610 ; 0305-1048
    ISSN (online) 1362-4962 ; 1362-4954
    ISSN 0301-5610 ; 0305-1048
    DOI 10.1093/nar/gkaa464
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  5. Article ; Online: Patterns of conservation of spliceosomal intron structures and spliceosome divergence in representatives of the diplomonad and parabasalid lineages.

    Hudson, Andrew J / McWatters, David C / Bowser, Bradley A / Moore, Ashley N / Larue, Graham E / Roy, Scott W / Russell, Anthony G

    BMC evolutionary biology

    2019  Volume 19, Issue 1, Page(s) 162

    Abstract: Background: Two spliceosomal intron types co-exist in eukaryotic precursor mRNAs and are excised by distinct U2-dependent and U12-dependent spliceosomes. In the diplomonad Giardia lamblia, small nuclear (sn) RNAs show hybrid characteristics of U2- and ... ...

    Abstract Background: Two spliceosomal intron types co-exist in eukaryotic precursor mRNAs and are excised by distinct U2-dependent and U12-dependent spliceosomes. In the diplomonad Giardia lamblia, small nuclear (sn) RNAs show hybrid characteristics of U2- and U12-dependent spliceosomal snRNAs and 5 of 11 identified remaining spliceosomal introns are trans-spliced. It is unknown whether unusual intron and spliceosome features are conserved in other diplomonads.
    Results: We have identified spliceosomal introns, snRNAs and proteins from two additional diplomonads for which genome information is currently available, Spironucleus vortens and Spironucleus salmonicida, as well as relatives, including 6 verified cis-spliceosomal introns in S. vortens. Intron splicing signals are mostly conserved between the Spironucleus species and G. lamblia. Similar to 'long' G. lamblia introns, RNA secondary structural potential is evident for 'long' (> 50 nt) Spironucleus introns as well as introns identified in the parabasalid Trichomonas vaginalis. Base pairing within these introns is predicted to constrain spatial distances between splice junctions to similar distances seen in the shorter and uniformly-sized introns in these organisms. We find that several remaining Spironucleus spliceosomal introns are ancient. We identified a candidate U2 snRNA from S. vortens, and U2 and U5 snRNAs in S. salmonicida; cumulatively, illustrating significant snRNA differences within some diplomonads. Finally, we studied spliceosomal protein complements and find protein sets in Giardia, Spironucleus and Trepomonas sp. PC1 highly- reduced but well conserved across the clade, with between 44 and 62 out of 174 studied spliceosomal proteins detectable. Comparison with more distant relatives revealed a highly nested pattern, with the more intron-rich fornicate Kipferlia bialata retaining 87 total proteins including nearly all those observed in the diplomonad representatives, and the oxymonad Monocercomonoides retaining 115 total proteins including nearly all those observed in K. bialata.
    Conclusions: Comparisons in diplomonad representatives and species of other closely-related metamonad groups indicates similar patterns of intron structural conservation and spliceosomal protein composition but significant divergence of snRNA structure in genomically-reduced species. Relative to other eukaryotes, loss of evolutionarily-conserved snRNA domains and common sets of spliceosomal proteins point to a more streamlined splicing mechanism, where intron sequences and structures may be functionally compensating for the minimalization of spliceosome components.
    MeSH term(s) 5' Untranslated Regions/genetics ; Base Pairing/genetics ; Base Sequence ; Conserved Sequence ; Diplomonadida/genetics ; Genome ; Introns/genetics ; Nucleic Acid Conformation ; Parabasalidea/genetics ; Phylogeny ; RNA Splicing/genetics ; RNA, Messenger/genetics ; RNA, Messenger/metabolism ; RNA, Small Nuclear/chemistry ; RNA, Small Nuclear/genetics ; Ribosomal Proteins/genetics ; Spliceosomes/genetics
    Chemical Substances 5' Untranslated Regions ; RNA, Messenger ; RNA, Small Nuclear ; Ribosomal Proteins
    Language English
    Publishing date 2019-08-02
    Publishing country England
    Document type Journal Article ; Research Support, Non-U.S. Gov't ; Research Support, U.S. Gov't, Non-P.H.S.
    ISSN 1471-2148
    ISSN (online) 1471-2148
    DOI 10.1186/s12862-019-1488-y
    Database MEDical Literature Analysis and Retrieval System OnLINE

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  6. Article ; Online: The Macronuclear Genome of Stentor coeruleus Reveals Tiny Introns in a Giant Cell.

    Slabodnick, Mark M / Ruby, J Graham / Reiff, Sarah B / Swart, Estienne C / Gosai, Sager / Prabakaran, Sudhakaran / Witkowska, Ewa / Larue, Graham E / Fisher, Susan / Freeman, Robert M / Gunawardena, Jeremy / Chu, William / Stover, Naomi A / Gregory, Brian D / Nowacki, Mariusz / Derisi, Joseph / Roy, Scott W / Marshall, Wallace F / Sood, Pranidhi

    Current biology : CB

    2017  Volume 27, Issue 4, Page(s) 569–575

    Abstract: The giant, single-celled organism Stentor coeruleus has a long history as a model system for studying pattern formation and regeneration in single cells. Stentor [1, 2] is a heterotrichous ciliate distantly related to familiar ciliate models, such as ... ...

    Abstract The giant, single-celled organism Stentor coeruleus has a long history as a model system for studying pattern formation and regeneration in single cells. Stentor [1, 2] is a heterotrichous ciliate distantly related to familiar ciliate models, such as Tetrahymena or Paramecium. The primary distinguishing feature of Stentor is its incredible size: a single cell is 1 mm long. Early developmental biologists, including T.H. Morgan [3], were attracted to the system because of its regenerative abilities-if large portions of a cell are surgically removed, the remnant reorganizes into a normal-looking but smaller cell with correct proportionality [2, 3]. These biologists were also drawn to Stentor because it exhibits a rich repertoire of behaviors, including light avoidance, mechanosensitive contraction, food selection, and even the ability to habituate to touch, a simple form of learning usually seen in higher organisms [4]. While early microsurgical approaches demonstrated a startling array of regenerative and morphogenetic processes in this single-celled organism, Stentor was never developed as a molecular model system. We report the sequencing of the Stentor coeruleus macronuclear genome and reveal key features of the genome. First, we find that Stentor uses the standard genetic code, suggesting that ciliate-specific genetic codes arose after Stentor branched from other ciliates. We also discover that ploidy correlates with Stentor's cell size. Finally, in the Stentor genome, we discover the smallest spliceosomal introns reported for any species. The sequenced genome opens the door to molecular analysis of single-cell regeneration in Stentor.
    MeSH term(s) Ciliophora/genetics ; Genome, Protozoan ; Introns/genetics ; Phylogeny ; Spliceosomes/metabolism ; Whole Genome Sequencing
    Keywords covid19
    Language English
    Publishing date 2017-02-09
    Publishing country England
    Document type Journal Article
    ZDB-ID 1071731-6
    ISSN 1879-0445 ; 0960-9822
    ISSN (online) 1879-0445
    ISSN 0960-9822
    DOI 10.1016/j.cub.2016.12.057
    Database MEDical Literature Analysis and Retrieval System OnLINE

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