1,478 research outputs found

    Effects of Hurricane Bret on Northern Bobwhite Survival in South Texas

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    The impacts of intense storms such as hurricanes on wildlife rarely are documented. We had the opportunity to monitor the impact of Hurricane Bret on northern bobwhite (Colinus virginianus) survival and reproduction in Brooks County, Texas. On 22 August 1999, Hurricane Bret struck our study area, which received \u3e 45 cm of rain and experienced wind gusts \u3e160 km/h. We documented the survival of bobwhite adults (n = 82), broods (n = 15), and nests (n = 4) via radiotelemetry before and after the hurricane. Only 11 (13%) adult bobwhites were killed, with 4 killed directly from exposure to the hurricane. Broods experienced higher mortality, with 7 (47%) broods killed during the hurricane. Six of the 7 dead broods were \u3c 1 week old. Sizes of the 8 surviving broods were reduced from a mean brood size of about 11 chicks prior to the hurricane to a mean size of 4 after the hurricane (P = 0.01). Of the 4 nests monitored, 3 were depredated and eggs in 1 nest hatched the weekend of the storm. Hurricanes may negatively impact the survival of young (i.e., \u3c 2 weeks old) bobwhite broods

    Binding of herpes simplex virus-1 US11 to specific RNA sequences

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    Herpes simplex virus-1 US11 is a RNA-binding protein with a novel RNA-binding domain. US11 has been reported to exhibit sequence- and conformation-specific RNA-binding, but the sequences and conformations important for binding are not known. US11 has also been described as a double-stranded RNA (dsRNA)-binding protein. To investigate the US11–RNA interaction, we performed in vitro selection of RNA aptamers that bind US11 from a RNA library consisting of >10(14) 80 base sequences which differ in a 30 base randomized region. US11 bound specifically to selected aptamers with an affinity of 70 nM. Analysis of 23 selected sequences revealed a strong consensus sequence. The US11 RNA-binding domain and ≤46 bases of selected RNA containing the consensus sequence were each sufficient for binding. US11 binding protected the consensus motif from hydroxyl radical cleavage. RNase digestions of a selected aptamer revealed regions of both single-stranded RNA and dsRNA. We observed that US11 bound two different dsRNAs in a sequence non-specific manner, but with lower affinity than it bound selected aptamers. The results define a relatively short specific sequence that binds US11 with high affinity and indicate that dsRNA alone does not confer high-affinity binding

    A computationally engineered RAS rheostat reveals RAS-ERK signaling dynamics.

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    Synthetic protein switches controlled with user-defined inputs are powerful tools for studying and controlling dynamic cellular processes. To date, these approaches have relied primarily on intermolecular regulation. Here we report a computationally guided framework for engineering intramolecular regulation of protein function. We utilize this framework to develop chemically inducible activator of RAS (CIAR), a single-component RAS rheostat that directly activates endogenous RAS in response to a small molecule. Using CIAR, we show that direct RAS activation elicits markedly different RAS-ERK signaling dynamics from growth factor stimulation, and that these dynamics differ among cell types. We also found that the clinically approved RAF inhibitor vemurafenib potently primes cells to respond to direct wild-type RAS activation. These results demonstrate the utility of CIAR for quantitatively interrogating RAS signaling. Finally, we demonstrate the general utility of our approach in design of intramolecularly regulated protein tools by applying it to the Rho family of guanine nucleotide exchange factors

    Closed forms and multi-moment maps

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    We extend the notion of multi-moment map to geometries defined by closed forms of arbitrary degree. We give fundamental existence and uniqueness results and discuss a number of essential examples, including geometries related to special holonomy. For forms of degree four, multi-moment maps are guaranteed to exist and are unique when the symmetry group is (3,4)-trivial, meaning that the group is connected and the third and fourth Lie algebra Betti numbers vanish. We give a structural description of some classes of (3,4)-trivial algebras and provide a number of examples.Comment: 36 page

    Interpenetration isomers in isoreticular amine-tagged zinc MOFs

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    The effect of increasing steric size of pendant amine substituents on structural isoreticulation has been studied systematically in a series of Zn-MOFs. Linear biphenyl dicarboxylic acids tagged with pendant primary amine (H2bpdc-NH2), allylamine (H2bpdc-NHallyl), diallylamine (H2bpdc-N(allyl)2) and dimethylamine (H2bpdc-NMe2) groups react with zinc nitrate in DMF to yield a set of interpenetrated MOFs, WUF-11-14, respectively, that are structurally akin to IRMOF-9. The allylated amine ligands undergo C-N cleavage reactions under the synthesis conditions, yielding WUF-12 and WUF-13 as multivariate MOFs. The single crystal X-ray crystallography on this set of MOFs was not straightforward and we give a salutary account of the difficulties encountered. Gas adsorption measurements combined with surface area calculations provide invaluable support for the crystallographic assignments. The crystallographic analyses reveal subtle differences in the relative positions of the interpenetrating frameworks, and we present a classification system for this type of MOF and analyse related examples available in the literature. CO2 adsorption measurements revealed that WUF-14, which features the strongest Brønsted basic dimethylamine tag group, has the highest capacity, isosteric heat of adsorption, and CO2/N2 selectivity.</p

    Organic carbon production, mineralization and preservation on the Peruvian margin

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    Carbon cycling in Peruvian margin sediments (11° S and 12° S) was examined at 16 stations from 74 m on the inner shelf down to 1024 m water depth by means of in situ flux measurements, sedimentary geochemistry and modeling. Bottom water oxygen was below detection limit down to ca. 400 m and increased to 53 μM at the deepest station. Sediment accumulation rates and benthic dissolved inorganic carbon fluxes decreased rapidly with water depth. Particulate organic carbon (POC) content was lowest on the inner shelf and at the deep oxygenated stations (< 5%) and highest between 200 and 400 m in the oxygen minimum zone (OMZ, 15–20%). The organic carbon burial efficiency (CBE) was unexpectedly low on the inner shelf (< 20%) when compared to a global database, for reasons which may be linked to the frequent ventilation of the shelf by oceanographic anomalies. CBE at the deeper oxygenated sites was much higher than expected (max. 81%). Elsewhere, CBEs were mostly above the range expected for sediments underlying normal oxic bottom waters, with an average of 51 and 58% for the 11° S and 12° S transects, respectively. Organic carbon rain rates calculated from the benthic fluxes alluded to a very efficient mineralization of organic matter in the water column, with a Martin curve exponent typical of normal oxic waters (0.88 ± 0.09). Yet, mean POC burial rates were 2–5 times higher than the global average for continental margins. The observations at the Peruvian margin suggest that a lack of oxygen does not affect the degradation of organic matter in the water column but promotes the preservation of organic matter in marine sediments
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