| 1. |
- Christmas, Matthew, et al.
(author)
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Evolutionary constraint and innovation across hundreds of placental mammals
- 2023
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In: Science. - : American Association for the Advancement of Science (AAAS). - 0036-8075 .- 1095-9203. ; 380:6643
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Journal article (peer-reviewed)abstract
- Zoonomia is the largest comparative genomics resource for mammals produced to date. By aligning genomes for 240 species, we identify bases that, when mutated, are likely to affect fitness and alter disease risk. At least 332 million bases (similar to 10.7%) in the human genome are unusually conserved across species (evolutionarily constrained) relative to neutrally evolving repeats, and 4552 ultraconserved elements are nearly perfectly conserved. Of 101 million significantly constrained single bases, 80% are outside protein-coding exons and half have no functional annotations in the Encyclopedia of DNA Elements (ENCODE) resource. Changes in genes and regulatory elements are associated with exceptional mammalian traits, such as hibernation, that could inform therapeutic development. Earth's vast and imperiled biodiversity offers distinctive power for identifying genetic variants that affect genome function and organismal phenotypes.
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| 2. |
- Hindle, Allyson G., et al.
(author)
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Low guanylyl cyclase activity in Weddell seals : implications for peripheral vasoconstriction and perfusion of the brain during diving
- 2019
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In: American Journal of Physiology. Regulatory Integrative and Comparative Physiology. - : AMER PHYSIOLOGICAL SOC. - 0363-6119 .- 1522-1490. ; 316:6, s. R704-R715
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Journal article (peer-reviewed)abstract
- Nitric oxide (NO) is a potent vasodilator, which improves perfusion and oxygen delivery during tissue hypoxia in terrestrial animals. The vertebrate dive response involves vasoconstriction in select tissues. which persists despite profound hypoxia. Using tissues collected from Weddell seals at necropsy, we investigated whether vasoconstriction is aided by downregulation of local hypoxia signaling mechanisms. We focused on NO-soluble guanylyl cyclasc (GC)-cGMP signaling, a well-known vasodilatory transduction pathway. Seals have a lower GC protein abundance. activity, and capacity to respond to NO stimulation than do terrestrial mammals. In seal lung homogenates, GC produced less cGMP (20.1 +/- 3.7 pmol.mg protein(-1).min(-1)) than the lungs of dogs (-80 +/- 144 pmol.mg protein(-1).min(-1) less than seals), sheep (-472 +/- 96), rats (-664 +/- 104) or mice ( -1,160 +/- 104, P < 0.0001). Amino acid sequences of the GC enzyme alpha-subunits differed between seals and terrestrial mammals, potentially affecting their structure and function. Vasoconstriction in diving Weddell seals is not consistent across tissues; perfusion is maintained in the brain and heart but decreased in other organs such as the kidney. A NO donor increased median GC activity 49.5-fold in the seal brain but only 27.4-fold in the kidney. consistent with the priority of cerebral perfusion during diving. Nos3 expression was high in the seal brain, which could improve NO production and vasodilatory potential. Conversely, Pde5a expression was high in the seal renal artery, which may increase cGMP breakdown and vasoconstriction in the kidney. Taken together, the results of this study suggest that alterations in the NO-cGMP pathway facilitate the diving response.
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| 3. |
- Noh, Hyun Ji, et al.
(author)
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The Antarctic Weddell seal genome reveals evidence of selection on cardiovascular phenotype and lipid handling
- 2022
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In: Communications Biology. - : Springer Nature. - 2399-3642. ; 5:1
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Journal article (peer-reviewed)abstract
- The Weddell seal (Leptonychotes weddellii) thrives in its extreme Antarctic environment. We generated the Weddell seal genome assembly and a high-quality annotation to investigate genome-wide evolutionary pressures that underlie its phenotype and to study genes implicated in hypoxia tolerance and a lipid-based metabolism. Genome-wide analyses included gene family expansion/contraction, positive selection, and diverged sequence (acceleration) compared to other placental mammals, identifying selection in coding and non-coding sequence in five pathways that may shape cardiovascular phenotype. Lipid metabolism as well as hypoxia genes contained more accelerated regions in the Weddell seal compared to genomic background. Top-significant genes were SUMO2 and EP300; both regulate hypoxia inducible factor signaling. Liver expression of four genes with the strongest acceleration signals differ between Weddell seals and a terrestrial mammal, sheep. We also report a high-density lipoprotein-like particle in Weddell seal serum not present in other mammals, including the shallow-diving harbor seal. The Antarctic Weddell inhabits one of the most extreme environments on Earth. Comparative genomics with close relatives reveals the specific genetic adaptations for cardiovascular and fat metabolism that enable it to thrive.
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