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131.
Anthony P. Fordham-Skelton F. Safadi M. Golovkin A. S. N. Reddy 《Plant Molecular Biology Reporter》1994,12(4):358-366
Calmodulin labeled with125I or34S has been used to screen expression libraries to isolate cDNAs encoding calmodulin-binding proteins (CBPs) from several eukaryotic
systems. The use of radiolabeled calmodulin has, however, several disadvantages. We have developed a nonradiactive method
to isolate cDNAs for CBPs using biotinylated calmodulin. Screening of a cDNA library in an expression vector with biotinylated
calmodulin resulted in the isolation of cDNAs encoding CBPs. Avidin and biotin blocking steps, prior to incubation of the
filters with biotinylated calmodulin, are found to be essential to eliminate the cDNAs that code for biotin-containing polypeptides.
The cDNA clones isolated using this nonradioactive method bound calmodulin in a calcium-dependent manner. The binding of biotinylated
calmodulin to these clones was completely abolished by ethylene glycolbis(\-aminoethylether)-N,N′-tetraacetic acid (EGTA),
a calcium chelator. Furthermore, the isolated cDNAs were confirmed by probing the clones with35S-labeled calmodulin. All the isolated clones bound to radiolabeled calmodulin in the presence of calcium but not in the presence
of EGTA. The method described here is simple, fast, and does not involve preparation and handing of radiolabeled calmodulin.
All the materials used in this method are commercially available; hence, this procedure should be widely applicable to isolate
cDNAs encoding CBPs from any eukaryotic organism. 相似文献
132.
Metallothionein (MT) is a ubiquitous mammalian protein comprising 61 or 62 nonaromatic amino acids of which 20 are cysteine residues. The high sulfhydryl content imparts to this protein a unique and remarkable ability to bind multiple metal ions in structurally significant metal–thiolate clusters. MT can bind seven divalent metal ions per protein molecule in two domains with exclusive tetrahedral metal coordination. The domain stoichiometries for the M7S20 structure are M4(Scys)11 (α domain) and M3(Scys)9 (β domain). Up to 12 Cu(I) ions can displace the 7 Zn2+ ions bound per molecule in Zn7–MT. The incoming Cu(I) ions adopt a trigonal planar geometry with domain stoichiometries for the Cu12S20 structure of Cu6(Scys)11 and Cu6(Scys)9 for the α and β domains, respectively. The circular dichroism (CD) spectra recorded as Cu+ is added to Zn7–MT to form Cu12–MT directly report structural changes that take place in the metal binding region. The spectrum arises under charge transfer transitions between the cysteine S and the Cu(I); because the Cu(I)–thiolate cluster units are located within the chiral binding site, intensities in the CD spectrum are directly related to changes in the binding site. The CD technique clearly indicates stoichiometries of several Cu(I)–MT species. Model Cu(I)–thiolate complexes, using the tripeptide glutathione as the sulfhydryl source, were examined by CD spectroscopy to obtain transition energies and the Cu(I)–thiolate coordination geometries which correspond to these bands. Possible structures for the Cu(I)–thiolate clusters in the α and β domains of Cu12–MT are proposed. © 1994 Wiley-Liss, Inc. 相似文献
133.
Anthony P. Clevenger 《Ecography》1994,17(3):257-263
Eurasian pine martens are considered habitat specialists, associated primarily with mature stands of mesic mixed wood forest habitats, and avoid areas without overhead cover The species is found throughout the temperate and boreal regions of the continent but on the Mediterranean island of Minorca, introduced pine martens thrive in a competitor- and predator-free environment I test the prediction that because of evolved prey-capture and predator avoidance strategies Minorcan martens should select habitats most similar to temperate and northern parts of their range Scat index routes were used to quantify pine marten habitat selection Marten did not demonstrate any habitat type preferences although observed use of pine forests and coastal shrublands was slighly greater than expected Marten were indifferent to overhead cover whereas mesic sites and areas of tall high shrub density were favored Small mammal trap indices and preferred prey suggested that martens commonly used non-forested areas My results demonstrated that on Minorca pine martens were habitat generalists In the absence of predators open non-forested habitats were equally important to pine marten as were forested ones 相似文献
134.
Anthony T.W. Cheung Richard B. Moss Geoffrey Kurland Albin B. Leong William J. Novick 《Journal of medical primatology》1993,22(4):257-262
We have recently established a rhesus monkey model of chronic Pseudomonas aeruginosa (PA) endobronchitis by bronchoscopic instillation of PA-embedded agar beads. All experimental animals developed chronic neutrophilic endobronchitis similar to chronic PA endobronchitis in cystic fibrosis (CF). Histopathologic studies further confirmed similarities to chronic PA endobronchitis in CF, including marked peribronchial inflammation, epithelial damage, presence of degraded cilia and ciliary abnormalities, appearance of PA bacterial clusters, mucosal hyperplasia, goblet cell hypertrophy/hypersecretion, airway obstruction, alveolar abnormalities, bronchiectasis, and fibrosis. 相似文献
135.
Strong-Gunderson Janet M. Palumbo Anthony V. 《Journal of industrial microbiology & biotechnology》1994,13(6):361-366
Summary A method is described for rapidly screening the metabolic potential of bacteria to oxidize semivolatile and volatile compounds as a sole carbon source. The method is based on automated system that utilizes MicroplatesTM manufactured by Biolog, Inc. (Hayward, CA, USA). This system detects bacterial respiratory activity from the oxidation of a carbon source introduced in volatile form. This is in contrast to the original design, which is based on inoculating a carbon source directly into each well. The 96-well (MT) microtiter plates contain nutrients and a tetrazolium dye. When a bacterial species is capable of oxidizing a volatile carbon substrate, the dye turns purple, and a spectrophotometric plate reader quantifies the response. As a test of this method 150 isolates, including isolates known to degrade some of the test compounds and negative controls were evaluated for their potential to oxidize carbon tetrachloride, toluene, ando-xylene. Thirty-seven isolates (25%) were qualitatively identified as contaminant oxidizers, and thirteen of these (35%) showed significant degradation capabilities for both toluene ando-xylene.Environmental Sciences Division Publication Number 4277. 相似文献
136.
Neil R. Brandt Anthony H. Caswell Stephanie A. Lewis Carl Donald G. Ferguson Tara Brandt Jean-Pierre Brunschwig Arthur L. Bassett 《The Journal of membrane biology》1993,131(3):219-228
Summary Dyads (transverse tubule—junctional sarcoplasmic reticulum complexes) were enriched from rat ventricle microsomes by continuous sucrose gradients. The major vesicle peak at 36% sucrose contained up to 90% of those membranes which possessed dihydropyridine (DHP) binding sites (markers for transverse tubules) and all membranes which possessed ryanodine receptors and the putative junctional foot protein (markers for junctional sarcoplasmic reticulum). In addition, the 36% sucrose peak contained half of the vesicles with muscarine receptors. Vesicles derived from the nonjunctional plasma membrane as defined by a low content of dihydropyridine binding sites per muscarine receptor and from the free sarcoplasmic reticulum as defined by the Mr 102K Ca2+ ATPase were associated with a diffuse protein band (22–30% sucrose) in the lighter region of the gradient. These organelles were recovered in low yield. Putative dyads were not broken by French press treatment at 8,000 psi and only partially disrupted at 14,000 psi. The monoclonal antibody GE4.90 against skeletal muscle triadin, a protein which links the DHP receptor to the junctional foot protein in skeletal muscle triad junctions, cross-reacted with a protein in rat dyads of the same Mr as triadin. Western blots of muscle microsomes from preparations which had been treated with 100mm iodoacetamide throughout the isolation procedure showed that cardiac triadin consisted predominantly of a band of Mr 95 kD. Higher molecular weight polymers were detectable but low in content, in contrast with the ladder of oligomeric forms in rat psoas muscle microsomes. Cardiac triadin was not dissolved from the microsomes by hypertonic salt or Triton X-100, indicating that it, as well as skeletal muscle triadin, was an integral protein of the junctional SR. The cardiac epitope was localized to the junctional SR by comparison of its distribution with that of organelle markers in both total microsome and in French press disrupted dyad preparations. Immunofluorescence localization of triadin using mAb GE4.90 revealed that intact rat ventricular muscle tissue was stained following a well-defined pattern of bands every sarcomere. This spacing of bands was consistent with the interpretation that triadin was present in the dyadic junctional regions. 相似文献
137.
Esterina Pascale Christine Liu Eulalia Valle Karen Usdin Anthony V. Furano 《Journal of molecular evolution》1993,36(1):9-20
Summary All modern mammals contain a distinctive, highly repeated (⩾50,000 members) family of long interspersed repeated DNA called
the L1 (LINE 1) family. While the modern L1 families were derived from a common ancestor that predated the mammalian radiation
∼80 million years ago, most of the members of these families were generated within the last 5 million years. However, recently
we demonstrated that modern murine (Old World rats and mice) genomes share an older long interspersed repeated DNA family
that we called Lx. Here we report our analysis of the DNA sequence of Lx family members and the relationship of this family
to the modern L1 families in mouse and rat. The extent of DNA sequence divergence between Lx members indicates that the Lx
amplification occurred about 12 million years ago, around the time of the murine radiation. Parsimony analysis revealed that
Lx elements were ancestral to both the modern rat and mouse L1 families. However, we found that few if any of the evolutionary
intermediates between the Lx and the modern L1 families were extensively amplified. Because the modern L1 families have evolved
under selective pressure, the evolutionary intermediates must have been capable of replication. Therefore, replicationcompetent
L1 elements can reside in genomes without undergoing extensive amplification. We discuss the bearing of our findings on the
evolution of L1 DNA elements and the mammalian genome. 相似文献
138.
Sanford D. Eigenbrode Anthony M. Shelton Wendy C. Kain Harry Leichtweis Terry D. Spittler 《Entomologia Experimentalis et Applicata》1993,69(1):41-50
S-ethyldipropylthiocarbamate (EPTC) applied as a soil treatment or over-the-top spray on cabbage plants (Brassica oleracea L.) caused the leaves to turn ‘glossy’ for as long as 30 days. EPTC-induced glossy plants were damaged significantly less
than untreated plants by diamondback moth,Plutella xylostella (L.), imported cabbage worm,Pieris rapae (L.), and cabbage looper,Trichoplusia ni (Hbn.). Reductions in damage were equivalent to those obtained from treatment with permethrin. When used in combination with
permethrin, EPTC provided additive control of damage by these pests. Our calculations show EPTC-induced resistance to be cost-effective.
This use of EPTC has several limitations, however. Younger plants (<9 leaves) were killed or injured by the herbicide. The
growth of older plants was not affected, but plants did not become glossy for ca. 10 days after they were treated with EPTC.
The crop must be protected with insecticides until the plants are mature enough to treat with EPTC, and until treated plants
become glossy. In addition, since the glossy trait is only effective against first instar larvae, populations of later instars
on glossy plants must be reduced with an application of insecticide. Finally, EPTC formulations are water-soluble and can
be washed away from the plants by heavy rains and irrigation, which may make this use of EPTC impractical in some situations.
Where its use is practical, and the indicated precautions are taken, EPTC-induced resistance could reduce dependence on chemical
insecticides and reduce selection for insecticide resistance in diamondback moth. 相似文献
139.
140.
Dennis A. Bazylinski Anthony J. Garratt-Reed Afshin Abedi Richard B. Frankel 《Archives of microbiology》1993,160(1):35-42
Greigite (Fe3S4) and pyrite (FeS2) particles in the magnetosomes of a many-celled, magnetotactic prokaryote (MMP), common in brackish-to-marine, sulfidic, aquatic habitats, contained relatively high concentrations of copper which ranged from about 0.1 to 10 atomic per cent relative to iron. In contrast, the greigite particles in the magnetosomes of a curved magnetotactic bacterium collected from the same sampling site did not contain significant levels of copper. The ability of the MMP to biomineralize copper within its magnetosomes appeared to be limited to that organism and dependent upon the site from which it was collected. Although the chemical mechanism and physiological function of copper accumulation in the magnetosomes of the MMP is unclear, the presence of copper is the first evidence that another transition metal ion could be incorporated in the mineral phase of the magnetosomes of a magnetotactic bacterium.Abbreviation MMP
many-celled magnetotactic prokaryote 相似文献