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Palaeogeography of tropical seasonal coastal wetlands in northern Britain during the early Mississippian Romer's Gap (2018)

MILLWARD, David, DAVIES, Sarah J., BRAND, Peter J., BROWNE, Michael A. E., BENNETT, Carys E., KEARSEY, Timothy I., SHERWIN, Janet E., MARSHALL, John E. A.

Cambridge University Press

In: Earth and Environmental Science Transactions of The Royal Society of Edinburgh

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Publication Date: 2018

Description: 〈div data-abstract-type="normal"〉〈p〉The lower Mississippian Ballagan Formation of northern Britain is one of only two successions worldwide to yield the earliest known tetrapods with terrestrial capability following the end-Devonian mass extinction event. Studies of the sedimentary environments and habitats in which these beasts lived have been an integral part of a major research project into how, why and under what circumstances this profound step in the evolution of life on Earth occurred. Here, a new palaeogeographic map is constructed from outcrop data integrated with new and archived borehole material. The map shows the extent of a very low-relief coastal wetland developed along the tropical southern continental margin of Laurussia. Coastal floodplains in the Midland Valley and Tweed basins were separated from the marginal marine seaway of the Northumberland–Solway Basin to the south by an archipelago of more elevated areas. A complex mosaic of sedimentary environments was juxtaposed, and included fresh and brackish to saline and hypersaline lakes, a diverse suite of floodplain palaeosols and a persistent fluvial system in the east of the region. The strongly seasonal climate led to the formation of evaporite deposits alternating with flooding events, both meteoric and marine. Storm surges drove marine floods from the SW into both the western Midland Valley and Northumberland–Solway Basin; marine water also flooded into the Tweed Basin and Tayside in the east. The Ballagan Formation is a rare example in the geological record of a tropical, seasonal coastal wetland that contains abundant, small-scale evaporite deposits. The diverse sedimentary environments and palaeosol types indicate a network of different terrestrial and aquatic habitats in which the tetrapods lived.〈/p〉〈/div〉

Print ISSN: 1755-6910

Electronic ISSN: 1755-6929

Topics: Geosciences

Published by Cambridge University Press

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Dynamic thiolation-thioesterase structure of a non-ribosomal peptide synthetase (2008)

D. P. Frueh ; H. Arthanari ; A. Koglin ; [et al.]

Nature Publishing Group (NPG)

In: Nature. 454(7206): 903-6. doi: 10.1038/nature07162.

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Publication Date: 2008-08-16

Description: Non-ribosomal peptide synthetases (NRPS) and polyketide synthases (PKS) produce numerous secondary metabolites with various therapeutic/antibiotic properties. Like fatty acid synthases (FAS), these enzymes are organized in modular assembly lines in which each module, made of conserved domains, incorporates a given monomer unit into the growing chain. Knowledge about domain or module interactions may enable reengineering of this assembly line enzymatic organization and open avenues for the design of new bioactive compounds with improved therapeutic properties. So far, little structural information has been available on how the domains interact and communicate. This may be because of inherent interdomain mobility hindering crystallization, or because crystallized molecules may not represent the active domain orientations. In solution, the large size and internal dynamics of multidomain fragments (〉35 kilodaltons) make structure determination by nuclear magnetic resonance a challenge and require advanced technologies. Here we present the solution structure of the apo-thiolation-thioesterase (T-TE) di-domain fragment of the Escherichia coli enterobactin synthetase EntF NRPS subunit. In the holoenzyme, the T domain carries the growing chain tethered to a 4'-phosphopantetheine whereas the TE domain catalyses hydrolysis and cyclization of the iron chelator enterobactin. The T-TE di-domain forms a compact but dynamic structure with a well-defined domain interface; the two active sites are at a suitable distance for substrate transfer from T to TE. We observe extensive interdomain and intradomain motions for well-defined regions and show that these are modulated by interactions with proteins that participate in the biosynthesis. The T-TE interaction described here provides a model for NRPS, PKS and FAS function in general as T-TE-like di-domains typically catalyse the last step in numerous assembly-line chain-termination machineries.〈br /〉〈br /〉〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2597408/" target="_blank"〉〈img src="https://static.pubmed.gov/portal/portal3rc.fcgi/4089621/img/3977009" border="0"〉〈/a〉 〈a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC2597408/" target="_blank"〉This paper as free author manuscript - peer-reviewed and accepted for publication〈/a〉〈br /〉〈br /〉〈span class="detail_caption"〉Notes: 〈/span〉Frueh, Dominique P -- Arthanari, Haribabu -- Koglin, Alexander -- Vosburg, David A -- Bennett, Andrew E -- Walsh, Christopher T -- Wagner, Gerhard -- EB 002026/EB/NIBIB NIH HHS/ -- GM066360/GM/NIGMS NIH HHS/ -- GM47467/GM/NIGMS NIH HHS/ -- P01 GM047467/GM/NIGMS NIH HHS/ -- P01 GM047467-11/GM/NIGMS NIH HHS/ -- P01 GM047467-110009/GM/NIGMS NIH HHS/ -- P01 GM047467-12/GM/NIGMS NIH HHS/ -- P01 GM047467-13/GM/NIGMS NIH HHS/ -- P01 GM047467-14/GM/NIGMS NIH HHS/ -- P01 GM047467-15/GM/NIGMS NIH HHS/ -- P01 GM047467-16/GM/NIGMS NIH HHS/ -- P01 GM047467-160012/GM/NIGMS NIH HHS/ -- P01 GM047467-17/GM/NIGMS NIH HHS/ -- P01 GM047467-170012/GM/NIGMS NIH HHS/ -- P41 EB002026/EB/NIBIB NIH HHS/ -- P41 EB002026-28/EB/NIBIB NIH HHS/ -- P41 EB002026-29/EB/NIBIB NIH HHS/ -- P41 EB002026-30/EB/NIBIB NIH HHS/ -- P41 EB002026-31/EB/NIBIB NIH HHS/ -- P41 EB002026-32/EB/NIBIB NIH HHS/ -- P41 EB002026-33/EB/NIBIB NIH HHS/ -- P41 GM066360/GM/NIGMS NIH HHS/ -- P41 GM066360-01/GM/NIGMS NIH HHS/ -- P41 GM066360-02/GM/NIGMS NIH HHS/ -- P41 GM066360-03/GM/NIGMS NIH HHS/ -- P41 GM066360-04/GM/NIGMS NIH HHS/ -- P41 GM066360-05/GM/NIGMS NIH HHS/ -- England -- Nature. 2008 Aug 14;454(7206):903-6. doi: 10.1038/nature07162.〈br /〉〈span class="detail_caption"〉Author address: 〈/span〉Department of Biological Chemistry and Molecular Pharmacology, Harvard Medical School, Boston, Massachusetts 02115, USA. dominique_frueh@hms.harvard.edu〈br /〉〈span class="detail_caption"〉Record origin:〈/span〉 〈a href="http://www.ncbi.nlm.nih.gov/pubmed/18704088" target="_blank"〉PubMed〈/a〉

Keywords: Binding Sites ; Catalysis ; Enterobactin/biosynthesis ; Escherichia coli/*enzymology/genetics ; Ligases/*chemistry/genetics/*metabolism ; Models, Molecular ; Multienzyme Complexes/*chemistry/genetics/*metabolism ; Nuclear Magnetic Resonance, Biomolecular ; *Peptide Biosynthesis, Nucleic Acid-Independent ; Protein Structure, Tertiary ; Protein Subunits/chemistry/genetics/metabolism

Print ISSN: 0028-0836

Electronic ISSN: 1476-4687

Topics: Biology , Chemistry and Pharmacology , Medicine , Natural Sciences in General , Physics

Published by Nature Publishing Group (NPG)

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Chemical shift correlation spectroscopy in rotating solids: Radio frequency-driven dipolar recoupling and longitudinal exchange (1992)

Bennett, A. E. ; Griffin, R. G. ; Ok, J. H. ; [et al.]

College Park, Md. : American Institute of Physics (AIP)

The Journal of Chemical Physics 96 (1992), S. 8624-8627

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ISSN: 1089-7690

Source: AIP Digital Archive

Topics: Physics , Chemistry and Pharmacology

Notes: We present a new method of performing chemical shift correlation spectroscopy in solids with magic angle spinning (MAS). Its key feature is a longitudinal mixing period of π pulses that recouples the dipolar interaction. We discuss experimental results for triply-13C-labeled alanine and a theory combining MAS and π pulses.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.462267

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Growth and chemical responses of trembling aspen to simulated browsing and ungulate saliva (2016)

Keefover-Ring, K., Rubert-Nason, K. F., Bennett, A. E., Lindroth, R. L.

Oxford University Press

In: Journal of Plant Ecology

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Publication Date: 2016-07-20

Description: Aims Woody plant-browser systems represent an understudied facet of herbivory. We subjected four genotypes of trembling aspen to artificial browsing, similar to that of a large mammalian herbivore, and applied deer saliva to clipped and unclipped trees to assess: (i) the effects of artificial browsing on aspen growth and phytochemistry of leaves and stems, (ii) genotypic variation in responses and (iii) potential alterations of responses by mammalian saliva. Methods Potted aspen trees were grown outdoors on the University of Wisconsin-Madison campus. The experiment consisted of a fully-crossed, 2 x 2 x 4 randomized complete block design, with two levels of artificial browsing (unclipped and clipped), two levels of saliva application (no saliva and saliva) and four aspen genotypes. To simulate ungulate browsing damage, we removed the upper 50% of the stem of half of the trees by pinching the stem with needle-nosed pliers and then separating it by tearing. For half of the damaged trees, we immediately swabbed the wound with deer saliva. Trees in the unclipped plus saliva treatment were swabbed with saliva at the 50% height mark. To assess the effects of clipping and saliva application, we harvested all trees after 2 months and measured various growth and chemical properties. Growth measurements included height, vertical growth, mass of leaves, stems and roots, leaf number and area and bud set. Chemical parameters included defensive, nutritional and structural components of both foliage and stems. Important Findings Clipping affected most of the growth parameters measured, decreasing tree height, leaf, stem, root and total tree mass and leaf area. Clipped trees had greater vertical growth, more leaves and higher specific leaf area (SLA) than unclipped trees. Deer saliva had little to no effect on plant growth response to the clipping treatment. Terminal budset was delayed by clipping and varied among genotypes but not in response to saliva application. Clipping also affected most of the phytochemical variables measured, reducing defensive compounds (phenolic glycosides and condensed tannins (CTs)) and nutrients (N), but increasing structural components (cellulose and lignin) in both leaves and stems. Saliva had very little effect on tree chemistry, causing only a slight decrease in the amount of CTs in leaves. In general, leaves contained more defensive compounds and nutrients, but much less cellulose, compared with stems. Genotypes differed for all physical and chemical indices, and in tolerance to damage as measured by vertical growth. In addition, for most of the physical and chemical variables measured, genotype interacted with the clipping treatment, suggesting that in natural stands some genotypes will resist or tolerate browsing better than others, affecting forest genetic composition and ultimately forest dynamics.

Print ISSN: 1752-993X

Electronic ISSN: 1752-9921

Topics: Biology

Published by Oxford University Press

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