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131.
Bunn JM Boyer DM Lipman Y St Clair EM Jernvall J Daubechies I 《American journal of physical anthropology》2011,145(2):247-261
Inferred dietary preference is a major component of paleoecologies of extinct primates. Molar occlusal shape correlates with diet in living mammals, so teeth are a potentially useful structure from which to reconstruct diet in extinct taxa. We assess the efficacy of Dirichlet normal energy (DNE) calculated for molar tooth surfaces for reflecting diet. We evaluate DNE, which uses changes in normal vectors to characterize curvature, by directly comparing this metric to metrics previously used in dietary inference. We also test whether combining methods improves diet reconstructions. The study sample consisted of 146 lower (mandibular) second molars belonging to 24 euarchontan taxa. Five shape quantification metrics were calculated on each molar: DNE, shearing quotient, shearing ratio, relief index, and orientation patch count rotated (OPCR). Statistical analyses were completed for each variable to assess effects of taxon and diet. Discriminant function analysis was used to assess ability of combinations of variables to predict diet. Values differ significantly by diets for all variables, although shearing ratios and OPCR do not distinguish statistically between insectivores and folivores or omnivores and frugivores. Combined analyses were much more effective at predicting diet than any metric alone. Alone, relief index and DNE were most effective at predicting diet. OPCR was the least effective alone but is still valuable as the only quantitative measure of surface complexity. Of all methods considered, DNE was the least methodologically sensitive, and its effectiveness suggests it will be a valuable tool for dietary reconstruction. 相似文献
132.
Rivalta I Amin M Luber S Vassiliev S Pokhrel R Umena Y Kawakami K Shen JR Kamiya N Bruce D Brudvig GW Gunner MR Batista VS 《Biochemistry》2011,50(29):6312-6315
Chloride binding in photosystem II (PSII) is essential for photosynthetic water oxidation. However, the functional roles of chloride and possible binding sites, during oxygen evolution, remain controversial. This paper examines the functions of chloride based on its binding site revealed in the X-ray crystal structure of PSII at 1.9 ? resolution. We find that chloride depletion induces formation of a salt bridge between D2-K317 and D1-D61 that could suppress the transfer of protons to the lumen. 相似文献
133.
134.
The absorption and energy transfer properties of photosynthetic pigments are strongly influenced by their local environment
or “site.” Local electrostatic fields vary in time with protein and chromophore molecular movement and thus transiently influence
the excited state transition properties of individual chromophores. Site-specific information is experimentally inaccessible
in many light-harvesting pigment–proteins due to multiple chromophores with overlapping spectra. Full quantum mechanical calculations
of each chromophores excited state properties are too computationally demanding to efficiently calculate the changing excitation
energies along a molecular dynamics trajectory in a pigment–protein complex. A simplified calculation of electrostatic interactions
with each chromophores ground to excited state transition, the so-called charge density coupling (CDC) for site energy, CDC,
has previously been developed to address this problem. We compared CDC to more rigorous quantum chemical calculations to determine
its accuracy in computing excited state energy shifts and their fluctuations within a molecular dynamics simulation of the
bacteriochlorophyll containing light-harvesting Fenna–Mathews–Olson (FMO) protein. In most cases CDC calculations differed
from quantum mechanical (QM) calculations in predicting both excited state energy and its fluctuations. The discrepancies
arose from the inability of CDC to account for the differing effects of charge on ground and excited state electron orbitals.
Results of our study show that QM calculations are indispensible for site energy computations and the quantification of contributions
from different parts of the system to the overall site energy shift. We suggest an extension of QM/MM methodology of site
energy shift calculations capable of accounting for long-range electrostatic potential contributions from the whole system,
including solvent and ions. 相似文献
135.
Jason E. Tanner Andrew D. Irving Milena Fernandes Doug Fotheringham Alicia McArdle Sue Murray‐Jones 《Ecological Management & Restoration》2014,15(3):168-179
Heavy losses of 6200 ha of seagrass off the Adelaide metropolitan coast since 1949 have had substantial implications for beach management, fisheries and biodiversity. Here, we describe for managers some promising initial trials to develop a cost‐effective method to rehabilitate some of these lost seagrasses. 相似文献
136.
David L. A. Gaveau Sean Sloan Elis Molidena Husna Yaen Doug Sheil Nicola K. Abram Marc Ancrenaz Robert Nasi Marcela Quinones Niels Wielaard Erik Meijaard 《PloS one》2014,9(7)
The native forests of Borneo have been impacted by selective logging, fire, and conversion to plantations at unprecedented scales since industrial-scale extractive industries began in the early 1970s. There is no island-wide documentation of forest clearance or logging since the 1970s. This creates an information gap for conservation planning, especially with regard to selectively logged forests that maintain high conservation potential. Analysing LANDSAT images, we estimate that 75.7% (558,060 km2) of Borneo''s area (737,188 km2) was forested around 1973. Based upon a forest cover map for 2010 derived using ALOS-PALSAR and visually reviewing LANDSAT images, we estimate that the 1973 forest area had declined by 168,493 km2 (30.2%) in 2010. The highest losses were recorded in Sabah and Kalimantan with 39.5% and 30.7% of their total forest area in 1973 becoming non-forest in 2010, and the lowest in Brunei and Sarawak (8.4%, and 23.1%). We estimate that the combined area planted in industrial oil palm and timber plantations in 2010 was 75,480 km2, representing 10% of Borneo. We mapped 271,819 km of primary logging roads that were created between 1973 and 2010. The greatest density of logging roads was found in Sarawak, at 0.89 km km−2, and the lowest density in Brunei, at 0.18 km km−2. Analyzing MODIS-based tree cover maps, we estimate that logging operated within 700 m of primary logging roads. Using this distance, we estimate that 266,257 km2 of 1973 forest cover has been logged. With 389,566 km2 (52.8%) of the island remaining forested, of which 209,649 km2 remains intact. There is still hope for biodiversity conservation in Borneo. Protecting logged forests from fire and conversion to plantations is an urgent priority for reducing rates of deforestation in Borneo. 相似文献
137.
Denise L. Driscoll Arijit Chakravarty Doug Bowman Vaishali Shinde Kerri Lasky Judy Shi Tricia Vos Bradley Stringer Ben Amidon Natalie D'Amore Marc L. Hyer 《PloS one》2014,9(11)
Plk1 is a checkpoint protein whose role spans all of mitosis and includes DNA repair, and is highly conserved in eukaryotes from yeast to man. Consistent with this wide array of functions for Plk1, the cellular consequences of Plk1 disruption are diverse, spanning delays in mitotic entry, mitotic spindle abnormalities, and transient mitotic arrest leading to mitotic slippage and failures in cytokinesis. In this work, we present the in vitro and in vivo consequences of Plk1 inhibition in cancer cells using potent, selective small-molecule Plk1 inhibitors and Plk1 genetic knock-down approaches. We demonstrate for the first time that cellular senescence is the predominant outcome of Plk1 inhibition in some cancer cell lines, whereas in other cancer cell lines the dominant outcome appears to be apoptosis, as has been reported in the literature. We also demonstrate strong induction of DNA double-strand breaks in all six lines examined (as assayed by γH2AX), which occurs either during mitotic arrest or mitotic-exit, and may be linked to the downstream induction of senescence. Taken together, our findings expand the view of Plk1 inhibition, demonstrating the occurrence of a non-apoptotic outcome in some settings. Our findings are also consistent with the possibility that mitotic arrest observed as a result of Plk1 inhibition is at least partially due to the presence of unrepaired double-strand breaks in mitosis. These novel findings may lead to alternative strategies for the development of novel therapeutic agents targeting Plk1, in the selection of biomarkers, patient populations, combination partners and dosing regimens. 相似文献
138.
Enveloped virus inactivation using neutral arginine solutions and applications in therapeutic protein purification processes
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Justin T. McCue Keith Selvitelli Doug Cecchini Rhonda Brown 《Biotechnology progress》2014,30(1):108-112
For the manufacturing of recombinant protein therapeutics produced from mammalian cell culture, demonstrating the capacity of the purification process to effectively clear infectious viruses is a regulatory requirement. At least two process steps, using different mechanisms of virus removal and/or inactivation, should be validated in support of the regulatory approval process. For example, exposure of the product stream to low pH, detergents or solvent/detergent combinations is commonly incorporated in protein purification processes for the inactivation of lipid‐enveloped viruses. However, some proteins have limited stability at low pH or in the presence of the detergents, and alternative techniques for achieving the inactivation of enveloped viruses would be beneficial. We present here an alternative and novel approach for the rapid inactivation of enveloped viruses using pH‐neutral buffer solutions containing arginine. The implementation of this approach in a monoclonal antibody or Fc‐fusion protein purification process is described and illustrated with several different therapeutic proteins. The use of the neutral pH arginine solution was able to effectively inactivate two enveloped model viruses, with no measurable effect on the product quality of the investigated proteins. Thus, the use of pH‐neutral arginine containing buffer solutions provides an alternative means of virus inactivation where other forms of virus inactivation, such as low pH and/or solvent/detergent treatments are not possible or undesirable due to protein stability limitations. © 2013 American Institute of Chemical Engineers Biotechnol. Prog., 30:108–112, 2014 相似文献
139.
Effects of pH and low density lipoprotein (LDL) on PCSK9-dependent LDL receptor regulation 总被引:2,自引:0,他引:2
140.
Eva S. Cunha Christine L. Hatem Doug Barrick 《Applied and environmental microbiology》2013,79(21):6684-6696
Degradation of cellulose for biofuels production holds promise in solving important environmental and economic problems. However, the low activities (and thus high enzyme-to-substrate ratios needed) of hydrolytic cellulase enzymes, which convert cellulose into simple sugars, remain a major barrier. As a potential strategy to stabilize cellulases and enhance their activities, we have embedded cellulases of extremophiles into hyperstable α-helical consensus ankyrin domain scaffolds. We found the catalytic domains CelA (CA, GH8; Clostridium thermocellum) and Cel12A (C12A, GH12; Thermotoga maritima) to be stable in the context of the ankyrin scaffold and to be active against both soluble and insoluble substrates. The ankyrin repeats in each fusion are folded, although it appears that for the C12A catalytic domain (CD; where the N and C termini are distant in the crystal structure), the two flanking ankyrin domains are independent, whereas for CA (where termini are close), the flanking ankyrin domains stabilize each other. Although the activity of CA is unchanged in the context of the ankyrin scaffold, the activity of C12A is increased between 2- and 6-fold (for regenerated amorphous cellulose and carboxymethyl cellulose substrates) at high temperatures. For C12A, activity increases with the number of flanking ankyrin repeats. These results showed ankyrin arrays to be a promising scaffold for constructing designer cellulosomes, preserving or enhancing enzymatic activity and retaining thermostability. This modular architecture will make it possible to arrange multiple cellulase domains at a precise spacing within a single polypeptide, allowing us to search for spacings that may optimize reactivity toward the repetitive cellulose lattice. 相似文献