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Splanchnic metabolism in exercising man 总被引:4,自引:0,他引:4
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A simplified procedure for cDNA and genomic library construction using nonpalindromic oligonucleotide adaptors 总被引:2,自引:0,他引:2
The properties and characteristics of oligonucleotide adaptors for use in a simplified procedure for the construction of cDNA and genomic DNA libraries are described. The adaptors are suitable for joining to blunt ended cDNA or sheared genomic DNA, and then to the cohesive ends of restriction sites in vectors. Each adaptor consists of two oligonucleotides with complementary but nonpalindromic sequences that include an internal restriction site, a 5' phosphorylated blunt end, and an overlapping or staggered 5' hydroxylated end corresponding to a restriction endonuclease site in a vector of choice. Ligation of the blunt end to high molecular weight target DNA proceeds efficiently and there is no tandem concatenation of the adaptor. Insertion into the appropriate vector only requires ligation of the cohesive ends. There is no requirement for methylation, restriction enzyme cleavage, G-C tailing, or denaturation after ligation of the adaptor to the target DNA, all characteristics of other procedures. 相似文献
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Aetosaur specimens from Howard County, Texas, USA, namedTypothorax meadei by Sawin (1947) represent a new genus here namedLongosuchus (type and only species -L. meadei). Longosu-chus is characterised by the possession of seven dentary teeth, a dentary excluded from the ventral margin of the lateral mandibular fenestra and by the angular, spinose lateral scutes throughout the dorsal region with lateral horns which have faceted sides.Longosuchus is found in mid-late Carnian strata in Texas, New Mexico and North Carolina, USA. Aetosaurs can be used to distinguish three successive biochrons in Late Triassic strata of the American Southwest, which are, in ascending order of age, theLongosuchus biochron, theStagonolepis biochron and theTypothorax biochron. 相似文献
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Bialaphos selection of stable transformants from maize cell culture 总被引:15,自引:0,他引:15
T. M. Spencer W. J. Gordon-Kamm R. J. Daines W. G. Start P. G. Lemaux 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》1990,79(5):625-631
Summary Stable transformed Black Mexican Sweet (BMS) maize callus was recovered from suspension culture cells bombarded with plasmid DNA that conferred resistance to the herbicide bialaphos. Suspension culture cells were bombarded with a mixture of two plasmids. One plasmid contained a selectable marker gene, bar, which encoded phosphinothricin acetyl transferase (PAT), and the other plasmid encoded a screenable marker for -glucuronidase (GUS). Bombarded cells were selected on medium containing the herbicide bialaphos, which is cleaved in plant cells to yield phosphinothricin (PPT), an inhibitor of glutamine synthetase. The bialaphos-resistant callus contained the bar gene and expressed PAT as assayed by PPT inactivation. Transformants that expressed high levels of PAT grew more rapidly on increasing concentrations of bialaphos than transformants expressing low levels of PAT. Fifty percent of the bialaphos-resistant transformants tested (8 of 16) expressed the nonselected gene encoding GUS. 相似文献
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The uv-visible spectra of 7,8-didemethyl-8-hydroxy-5-deazaflavin-5'-phosphoryllactyl glutamate (coenzyme F420), a naturally occurring 5-deazaflavin derivative, in three different buffers changed with a rise in temperature; the effect on the extinction coefficient at 420 nm (epsilon 420) was as follows: In phosphate-buffered solutions at pH less than 7.5, the epsilon 420 increased (at pH 5.0 for a temperature shift from 15 to 60 degrees C, delta epsilon 420 was +87%), but between pH 7.5 and 8, epsilon 420 changed very little. At pH greater than 8.0 in phosphate- or borate-buffered solutions, epsilon 420 decreased slightly. In morpholineethanesulfonic acid (Mes)-buffered F420 solutions at pH 5 and 5.5, epsilon 420 changed very little, whereas at pH 6-8, the epsilon 420 decreased. Absorbance of F420 at 401 nm in phosphate buffer at pH 5 to 9 was not significantly affected by temperature. Changes in epsilon 420 due to temperature change corresponded to changes in the pKa of 8-OH of the deazaflavin molecule; studies with adenylated F420 showed that the 8-OH of F420 was responsible for these changes.(ABSTRACT TRUNCATED AT 250 WORDS) 相似文献