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- Gemmell, Neil J., et al.
(författare)
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The tuatara genome reveals ancient features of amniote evolution
- 2020
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Ingår i: Nature. - : Springer Nature. - 0028-0836 .- 1476-4687. ; 584:7821, s. 403-409
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Tidskriftsartikel (refereegranskat)abstract
- The tuatara (Sphenodon punctatus)—the only living member of the reptilian order Rhynchocephalia (Sphenodontia), once widespread across Gondwana1,2—is an iconic species that is endemic to New Zealand2,3. A key link to the now-extinct stem reptiles (from which dinosaurs, modern reptiles, birds and mammals evolved), the tuatara provides key insights into the ancestral amniotes2,4. Here we analyse the genome of the tuatara, which—at approximately 5 Gb—is among the largest of the vertebrate genomes yet assembled. Our analyses of this genome, along with comparisons with other vertebrate genomes, reinforce the uniqueness of the tuatara. Phylogenetic analyses indicate that the tuatara lineage diverged from that of snakes and lizards around 250 million years ago. This lineage also shows moderate rates of molecular evolution, with instances of punctuated evolution. Our genome sequence analysis identifies expansions of proteins, non-protein-coding RNA families and repeat elements, the latter of which show an amalgam of reptilian and mammalian features. The sequencing of the tuatara genome provides a valuable resource for deep comparative analyses of tetrapods, as well as for tuatara biology and conservation. Our study also provides important insights into both the technical challenges and the cultural obligations that are associated with genome sequencing.
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| 2. |
- Best, Jonathan G., et al.
(författare)
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Optimal timing of anticoagulation after acute ischemic stroke with atrial fibrillation (OPTIMAS) : Protocol for a randomized controlled trial
- 2022
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Ingår i: International Journal of Stroke. - : SAGE Publications. - 1747-4930 .- 1747-4949. ; 17:5, s. 583-589
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Tidskriftsartikel (refereegranskat)abstract
- Rationale: Atrial fibrillation causes one-fifth of ischemic strokes, with a high risk of early recurrence. Although long-term anticoagulation is highly effective for stroke prevention in atrial fibrillation, initiation after stroke is usually delayed by concerns over intracranial hemorrhage risk. Direct oral anticoagulants offer a significantly lower risk of intracranial hemorrhage than other anticoagulants, potentially allowing earlier anticoagulation and prevention of recurrence, but the safety and efficacy of this approach has not been established. Aim: Optimal timing of anticoagulation after acute ischemic stroke with atrial fibrillation (OPTIMAS) will investigate whether early treatment with a direct oral anticoagulant, within four days of stroke onset, is as effective or better than delayed initiation, 7 to 14 days from onset, in atrial fibrillation patients with acute ischemic stroke. Methods and design: OPTIMAS is a multicenter randomized controlled trial with blinded outcome adjudication. Participants with acute ischemic stroke and atrial fibrillation eligible for anticoagulation with a direct oral anticoagulant are randomized 1:1 to early or delayed initiation. As of December 2021, 88 centers in the United Kingdom have opened. Study outcomes: The primary outcome is a composite of recurrent stroke (ischemic stroke or symptomatic intracranial hemorrhage) and systemic arterial embolism within 90 days. Secondary outcomes include major bleeding, functional status, anticoagulant adherence, quality of life, health and social care resource use, and length of hospital stay. Sample size target: A total of 3478 participants assuming event rates of 11.5% in the control arm and 8% in the intervention arm, 90% power and 5% alpha. We will follow a non-inferiority gatekeeper analysis approach with a non-inferiority margin of 2 percentage points. Discussion: OPTIMAS aims to provide high-quality evidence on the safety and efficacy of early direct oral anticoagulant initiation after atrial fibrillation-associated ischemic stroke. Trial registrations: ISRCTN: 17896007; ClinicalTrials.gov: NCT03759938
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| 3. |
- Johansson, Åke, et al.
(författare)
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A geochronological review of magmatism along the external margin of Columbia and in the Grenville-age orogens forming the core of Rodinia
- 2022
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Ingår i: Precambrian Research. - : Elsevier BV. - 0301-9268 .- 1872-7433. ; 371, s. 1-43
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Tidskriftsartikel (refereegranskat)abstract
- A total of 4344 magmatic U-Pb ages in the range 2300 to 800 Ma have been compiled from the Great Proterozoic Accretionary Orogen along the margin of the Columbia / Nuna supercontinent and from the subsequent Grenvillian collisional orogens forming the core of Rodinia. The age data are derived from Laurentia (North America and Greenland, n = 1212), Baltica (NE Europe, n = 1922), Amazonia (central South America, n = 625), Kalahari (southern Africa and Dronning Maud Land in East Antarctica, n = 386), and western Australia (n = 199). Laurentia, Baltica, and Amazonia (and possibly other cratons) most likely formed a ca. 10 000-km-long external active continental margin of Columbia from its assembly at ca. 1800 Ma until its dispersal at ca. 1260 Ma, after which all cratons studied were involved in the Rodinia-forming Grenvillian orogeny. However, the magmatic record is not smooth and even but highly irregular, with marked peaks and troughs, both for individual cratons and the combined data set. Magmatic peaks typically range in duration from a few tens of million years up to around hundred million years, with intervening troughs of comparable length. Some magmatic peaks are observed on multiple cratons, either by coincidence or because of paleogeographic proximity and common tectonic setting, while others are not. The best overall correlation, 0.617, is observed between Baltica and Amazonia, consistent with (but not definitive proof of) their being close neighbours in a SAMBA-like configuration at least in Columbia, and perhaps having shared the same peri-Columbian subduction system for a considerable time. Correlation factors between Laurentia and Baltica, or Laurentia and Amazonia, are below 0.14. Comparison between the Grenville Province in northeastern Laurentia and the Sveconorwegian Province in southwestern Fennoscandia (Baltica) shows some striking similarities, especially in the Mesoproterozoic, but also exhibits differences in the timing of events, especially during the final Grenville-Sveconorwegian collision, when the Sveconorwegian evolution seems to lag behind by some tens of million years. Between the other cratons, the evolution before and during the final Grenvillian collision is also largely diachronous. After 900 Ma, magmatic activity had ceased in all areas investigated, attesting to the position of most of them within the stable interior of Rodinia.
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