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101.
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Dependence on wild seed sources is often impractical for large‐scale habitat restoration programs. Reliance on commercial seed supplies of unknown provenance and fitness is thereby warranted. Little consideration has been given, however, to how the large volumes of seed required should be sourced. We evaluated commercial and locally collected seed sources for potential use in a New York State‐based, landscape‐scale program for restoring blue lupine Lupinus perennis. Through analysis of microsatellite markers we determined that “native” lupine designations by some commercial suppliers were in fact interspecific hybrids and therefore unreliable; at least two commercial sources, however, were genetically as close to native New York populations as native New York populations were to one other. Common garden experiments revealed that seed source influenced first‐year overwintering survival and subsequent height growth of surviving plants; seed sources more closely related genetically to native New York populations survived better and produced more stems per individual in the field in the area targeted for restoration. We conclude that (1) commercial suppliers often but not always offer reliably characterized seed sources of sufficient genetic similarity to native populations to warrant their use in restoration projects and (2) genetic affinity of potential seed stock to native populations is positively related to its fitness in the environment targeted for restoration. 相似文献
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Two dodecachlorinated porphyrins, 2,3,7,8,12,13,17,18-octachloro-5,10,15,20-tetra(4-chlorophenyl)porphyrin free base (TCl12PPH2) and its nickel compound (TCl12PPNi), have been synthesized. Single-crystal X-ray diffraction analysis shows that porphyrin rings are heavily distorted and exhibit saddled conformations. The Soret and Q bands of two compounds are red-shifted compared to their non-chlorinated counterparts. Theoretical calculations reveal that the optical band gap of TCl12PPH2 is reduced, whereas that of TCl12PPNi remains almost the same as to its non-chlorinated nickel compound due to the concurrent lowering of HOMO and LUMO energy levels. The frontier molecular orbitals are degenerated due to the decrease of symmetry of the molecules. 相似文献
105.
Colin R. Andrew Jane Han Tanneke den Blaauwen Gertie van Pouderoyen Erik Vijgenboom Gerard W. Canters Thomas M. Loehr J. Sanders-Loehr 《Journal of biological inorganic chemistry》1997,2(1):98-107
In the redox center of azurin, the Cu(II) is strongly coordinated to one thiolate S from Cys 112 and two imidazole Ns from
His 46 and 117. This site yields a complex resonance Raman (RR) spectrum with >20 vibrational modes between 200 and 1500 cm–1. We have investigated the effects of ligand-selective isotope replacements on the RR spectrum of Pseudomonas aeruginosa azurin to determine the relative spectral contribution from each of the copper ligands. Growth on 34S-sulfate labels the cysteine ligand and allows the identification of a cluster of bands with Cu–S(Cys) stretching character
between 370 and 430 cm–1 whose frequencies are consistent with the trigonal or distorted tetrahedral coordination in type 1 sites. In type 2 copper-cysteinate
sites, the lower ν (Cu–S) frequencies between 260 and 320 cm–1 are consistent with square-planar coordination. Addition of exogenous
15N-labeled imidazole or histidine to the His117Gly mutant generates type 1 or type 2 sites, respectively. Because neither the
above nor the His46Gly mutant reconstituted with 15N-imidazole exhibits significant isotope dependence, the histidine ligands can be ruled out as important contributors to the
RR spectrum. Instead, a variety of evidence, including extensive isotope shifts upon global substitution with 15N, suggests that the multiple RR modes of azurin are due principally to vibrations of the cysteine ligand. These are resonance-enhanced
through kinematic coupling with the Cu–S stretch in the ground state or through an excited-state A-term mechanism involving
a Cu-cysteinate chromophore that extends into the peptide backbone.
Received: 29 July 1996 / Accepted: 9 November 1996 相似文献
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Dual roles of plcA in Listeria monocytogenes pathogenesis 总被引:26,自引:5,他引:21
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