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  • 1
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    American Association for the Advancement of Science (AAAS)
    Publication Date: 2011-03-10
    Description: DNA transposons are mobile genetic elements that have shaped the genomes of eukaryotes for millions of years, yet their origins remain obscure. We discovered a virophage that, on the basis of genetic homology, likely represents an evolutionary link between double-stranded DNA viruses and Maverick/Polinton eukaryotic DNA transposons. The Mavirus virophage parasitizes the giant Cafeteria roenbergensis virus and encodes 20 predicted proteins, including a retroviral integrase and a protein-primed DNA polymerase B. On the basis of our data, we conclude that Maverick/Polinton transposons may have originated from ancient relatives of Mavirus, and thereby influenced the evolution of eukaryotic genomes, although we cannot rule out alternative evolutionary scenarios.〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Fischer, Matthias G -- Suttle, Curtis A -- New York, N.Y. -- Science. 2011 Apr 8;332(6026):231-4. doi: 10.1126/science.1199412. Epub 2011 Mar 3.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Microbiology and Immunology, 1365-2350 Health Sciences Mall, University of British Columbia, Vancouver V6T 1Z3, Canada.〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/21385722" target="_blank"〉PubMed〈/a〉
    Keywords: Amino Acid Sequence ; *DNA Transposable Elements ; DNA Viruses/*genetics/*physiology ; DNA, Viral/genetics ; DNA-Directed DNA Polymerase/genetics ; *Evolution, Molecular ; Genome, Viral ; Integrases/chemistry/genetics ; Molecular Sequence Data ; Phylogeny ; Satellite Viruses/*genetics/*physiology ; Stramenopiles/virology ; Viral Proteins/chemistry/genetics ; Virus Replication
    Print ISSN: 0036-8075
    Electronic ISSN: 1095-9203
    Topics: Biology , Chemistry and Pharmacology , Computer Science , Medicine , Natural Sciences in General , Physics
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  • 2
    Publication Date: 2010-10-25
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 3
    Publication Date: 2015-09-23
    Description: The virus world in which we live will never cease to amaze us. Historically, viruses were studied primarily from medical and economic perspectives; however, the last decades have shown that viruses play roles far more versatile than we could have imagined. Being the most abundant biological entities on the planet...
    Print ISSN: 0027-8424
    Electronic ISSN: 1091-6490
    Topics: Biology , Medicine , Natural Sciences in General
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  • 4
    Publication Date: 2012-07-10
    Description: Aims The dispersal of pollen and seeds is spatially restricted and may vary among plant populations because of varying biotic interactions, population histories or abiotic conditions. Because gene dispersal is spatially restricted, it will eventually result in the development of spatial genetic structure (SGS), which in turn can allow insights into gene dispersal processes. Here, we assessed the effect of habitat characteristics like population density and community structure on small-scale SGS and estimate historical gene dispersal at different spatial scales. Methods In a set of 12 populations of the subtropical understory shrub Ardisia crenata , we assessed genetic variation at 7 microsatellite loci within and among populations. We investigated small-scale genetic structure with spatial genetic autocorrelation statistics and heterogeneity tests and estimated gene dispersal distances based on population differentiation and on within-population SGS. SGS was related to habitat characteristics by multiple regression. Important Findings The populations showed high genetic diversity ( H e = 0.64) within populations and rather strong genetic differentiation ( $${{F}^{\prime }}_{\hbox{ ST }}$$ = 0.208) among populations, following an isolation-by-distance pattern, which suggests that populations are in gene flow–drift equilibrium. Significant SGS was present within populations (mean Sp = 0.027). Population density and species diversity had a joint effect on SGS with low population density and high species diversity leading to stronger small-scale SGS. Estimates of historical gene dispersal from between-population differentiation and from within-population SGS resulted in similar values between 4.8 and 22.9 m. The results indicate that local-ranged pollen dispersal and inefficient long-distance seed dispersal, both affected by population density and species diversity, contributed to the genetic population structure of the species. We suggest that SGS in shrubs is more similar to that of herbs than to trees and that in communities with high species diversity gene flow is more restricted than at low species diversity. This may represent a process that retards the development of a positive species diversity–genetic diversity relationship.
    Print ISSN: 1752-993X
    Electronic ISSN: 1752-9921
    Topics: Biology
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  • 5
    Publication Date: 2017-04-27
    Description: The formation of the biophotonic gyroid material in butterfly wing scales is an exceptional feat of evolutionary engineering of functional nanostructures. It is hypothesized that this nanostructure forms by chitin polymerization inside a convoluted membrane of corresponding shape in the endoplasmic reticulum. However, this dynamic formation process, including whether membrane folding and chitin expression are simultaneous or sequential processes, cannot yet be elucidated by in vivo imaging. We report an unusual hierarchical ultrastructure in the butterfly Thecla opisena that, as a solid material, allows high-resolution three-dimensional microscopy. Rather than the conventional polycrystalline space-filling arrangement, a gyroid occurs in isolated facetted crystallites with a pronounced size gradient. When interpreted as a sequence of time-frozen snapshots of the morphogenesis, this arrangement provides insight into the formation mechanisms of the nanoporous gyroid material as well as of the intracellular organelle membrane that acts as the template.
    Electronic ISSN: 2375-2548
    Topics: Natural Sciences in General
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