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1.
Investing in ecosystem health: Using rivers as a case study 总被引:2,自引:0,他引:2
Jeff Bennett 《Ecological Management & Restoration》2002,3(2):104-107
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Marianne E. Walsh Charles M. Collins Thomas F. Jenkins Alan D. Hewitt Jeff Stark Karen Myers 《Soil & Sediment Contamination》2003,12(5):631-645
Fort Greely, Alaska has an extensive complex of weapon training and testing areas located on lands withdrawn from the public domain under the Military Lands Withdrawal Act (PL106-65). The Army has pledged to implement a program to identify possible munitions contamination. Because of the large size (344,165,000 m2) of the high hazard impact areas, characterization of these constituents will be difficult. We used an authoritative sampling design to find locations most likely to contain explosives-residues on three impact areas. We focused our sampling on surface soils and collected multi-increment and discrete samples at locations of known firing events and from areas on the range that had craters, pieces of munitions, targets, or a designation as a firing point. In the two impact areas used primarily by the Army, RDX was the most frequently detected explosive. In the impact area that was also used by the Air Force, TNT was the most frequently detected explosive. Where detected, the explosives concentrations generally were low (<0.05 mg/kg) except in soils near low-order detonations, where the explosive-filler was in contact with the soil surface. These low-order detonations potentially can serve as localized sources for groundwater contamination if positioned in recharge areas. 相似文献
4.
Jeff A Johnson Heather RL Lerner Pamela C Rasmussen David P Mindell 《BMC evolutionary biology》2006,6(1):65-12
Background
Populations of the Oriental White-backed Vulture (Gyps bengalensis) have declined by over 95% within the past decade. This decline is largely due to incidental consumption of the non-steroidal anti-inflammatory veterinary pharmaceutical diclofenac, commonly used to treat domestic livestock. The conservation status of other Gyps vultures in southern Asia is also of immediate concern, given the lack of knowledge regarding status of their populations and the continuing existence of taxonomic uncertainties. In this study, we assess phylogenetic relationships for all recognized species and the majority of subspecies within the genus Gyps. The continuing veterinary use of diclofenac is an unknown but potential risk to related species with similar feeding habits to Gyps bengalensis. Therefore, an accurate assessment of the phylogenetic relationships among Gyps vultures should aid in their conservation by clarifying taxonomic uncertainties, and enabling inference of their respective relatedness to susceptible G. bengalensis. 相似文献5.
Agnes Cseplö Thure Etzold Jeff Schell Peter H. Schreier 《Molecular & general genetics : MGG》1988,214(2):295-299
Summary Experiments designed to establish stable chloroplast transformation require selectable marker genes encoded by the chloroplast genome. The antibiotic lincomycin is a specific inhibitor of chloroplast ribosomal activity and is known to bind to the large ribosomal subunit. We have investigated a defined region of the chloroplast 23 S rRNA genes from four lincomycin resistant Nicotiana plumbaginifolia mutants and from wild-type N. plumbaginifolia. The mutants LR415, LR421 and LR446 have A to G transitions at positions equivalent to the nucleotides 2058 and 2059 in the Escherichia coli 23 S rRNA. The mutant, LR400, possesses a G to A transition at a position corresponding to nucleotide 2032 of the E. coli 23 S rRNA. 相似文献
6.
TFIIA induces conformational changes in TFIID via interactions with the basic repeat. 总被引:5,自引:0,他引:5
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D K Lee J DeJong S Hashimoto M Horikoshi R G Roeder 《Molecular and cellular biology》1992,12(11):5189-5196
DNA-binding studies with Saccharomyces cerevisiae TFIID point mutants indicated that TFIIA interacts with the basic repeat region of TFIID and induces structural changes. The latter was shown by the ability of TFIIA to compensate for TFIID point mutants defective for DNA binding. Interaction with TFIIA also rendered TFIID binding temperature independent, thus mimicking the effect of removing the nonconserved N terminus of TFIID. In addition, N-terminal truncation of the TFIID point mutants defective for DNA binding mimicked the ability of TFIIA to restore DNA binding of those mutants. Taken together, these results suggest that TFIIA enhances TFIID binding to DNA by eliminating an otherwise inhibitory effect of the nonconserved N terminus of TFIID. Furthermore, analyses of TFIID contact points on DNA and binding studies with TATA-containing oligonucleotide probes showed that TFIIA decreases the effect of sequences flanking the adenovirus major late TATA element on TFIID binding to DNA, suggesting a possible role of TFIIA in allowing TFIID to recognize a wider variety of promoters. 相似文献
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Jeff Alexander J. Alan Payne Brian Shigekawa Jeffrey A. Frelinger Peter Cresswell 《Immunogenetics》1990,31(3):169-178
The transport of human-mouse hybrid class I histocompatibility antigens has been studied in a mutant human cell line, 174 × CEM.T2 (T2). T2, a somatic cell hybrid of human B- and T-lymphoblastoid cell lines (B-LCL and T-LCL, respectively), synthesizes HLA-A2 and HLA-B5 glycoproteins, but expresses only low levels of A2 and undetectable levels of B5 at the cell surface. We have previously shown that the products of human class I genes introduced into T2 by transfection behave like the endogenous HLA-B5 glycoproteins, while the products of mouse class I alleles similarly introduced are transported normally to the cell surface. We have now determined that the surface expression of class I glycoproteins in T2 depends on the origin of the 1 and 2 domains. Human (HLA-B7) and mouse (H-2D
p
) hybrid class I genes, encoding the leader, 1, and 2 sequences of one species fused to the 3, transmembrane, and cytoplasmic domains of the other, were transfected into T2. Normal surface expression of the hybrid class I molecule was observed in T2 only when the leader, 1, and 2-encoding exons were derived from the mouse gene. The reciprocal construct, encoding human leader, 1, and 2 domains fused to the mouse 3, transmembrane, and cytoplasmic regions, resulted in biosynthesis of a hybrid glycoprotein which was not transported to the cell surface. The products of both constructs were expressed normally in control cells. The effects of glycosylation on class I antigen transport were also studied using mutant class I constructs with altered glycosylation sites. Two mutant B7 genes encoding either an extra glycosylation site at position 176 or no glycosylation sites were transfected into T2. These mutant products were expressed at the cell surface in control cells, but were synthesized and not surface-expressed in T2. These data demonstrate that the HLA/H-2 transport dichotomy in T2 is a function of the origin of the 1 and/or 2 domains of the class I glycoprotein, and is not a reflection of glycosylation differences between the human and mouse molecules.
Offprint requests to: P. Cresswell. 相似文献
10.
Jeff Reeve Lorraine H. Kligman Robert Anderson 《Applied microbiology and biotechnology》1990,33(2):161-166
Summary Isolated lipids from Deinococcus radiodurans were reconstituted at final concentrations of 1 mg/ml into dioleoyl phosphatidyl choline (DOPC) vesicles and assayed for the ability to protect cells of Escherichia coli against killing by UV light (254 nm). Values of D37 (UV dose required to reduce the number of surviving cells to 37% of the original number) were calculated from killing curves. E. coli was afforded the greatest protection with an individual lipid, identified as vitamin MK8 (D37=310 J//m2, compared to D37=67 J/m2 for E. coli irradiated in the presence of DOPC alone). Liposome-mediated protection was dependent on UV254 absorbance and not on turbidity-related light-scattering. BOth vitamin MK8 from D. radiodurans and vitamin K1, which is available commercially, showed a similar degree of UV254-protection for E. coli. The UV-protective properties of vitamin K1 were also investigated on mammalian cells in comparison with other natural lipids and known sunscreens. Survival curves were obtained for mouse fibroblast (L) cells irradiated at UV254 in the absence or presence of DOPC liposomes into which were incorporated various natural lipids or standard sunscreen ingredients, all at final concentrations of 1 mg/ml. Experimentally determined values of D37 were as follows: Vitamin K1, 73 J/m2; \-carotene, 44 J/m2; -tocopherol, 20 J/m2; sulisobenzone, 156 J/m2; p-aminobenzoic acid (PABA), 113 J/m2; benzophenone, 80 J/m2; oxybenzone, 61 J/m2 and DOPC alone. 23 J/m2. Vitamin K1, the most protective lipid tested, was also compared with PABA and oxybenzone (all at concentrations of 20 mg/ml; applied topicall) for its ability to protec Skh-hairless mice from UV254-induced erythema, yielding a UV254 protection factor of 3.5. In addition, vitamin K1 (at 100 mg/ml) was able to provide hairless mice with a small degree of UVB protection, as indicated by an experimentally determined Solar Protection Factor of 1.5–2.0. Although it is concluded that vitamin K is not likely to account for the extraordinarily high degree of UV-resistance of D. radiodurans, vitamin K does show characteristics worthy of its consideration as a UV-screening agent.
Offprint requests to: R. Anderson 相似文献