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排序方式: 共有262条查询结果,搜索用时 15 毫秒
1.
2.
Quantitation of free sphingosine in liver by high-performance liquid chromatography 总被引:10,自引:0,他引:10
A H Merrill E Wang R E Mullins W C Jamison S Nimkar D C Liotta 《Analytical biochemistry》1988,171(2):373-381
Conditions were established for the extraction of free sphingosine from liver and the separation and quantitation of this and other long-chain (sphingoid) bases (e.g., sphingosine, sphinganine, phytosphingosine, and homologs) by reverse-phase high-performance liquid chromatography (HPLC). The long-chain bases were extracted with chloroform and methanol and then treated with base to remove interfering lipids. After preparation of the o-phthalaldehyde derivatives, the long-chain bases could be separated using C18 columns eluted isocratically with methanol:5 mM potassium phosphate, pH 7.0 (90:10). The HPLC analyses took 15 to 20 min per sample and had lower limits of detection in the picomole range. Quantitation was facilitated by using a 20-carbon long-chain base homolog as an internal standard. The utility of the method was demonstrated with rat liver, providing the first quantitation of free sphingosine in this tissue of approximately 7 nmol/g wet wt. 相似文献
3.
Population genetics and phylogenetics of DNA sequence variation at multiple loci within the Drosophila melanogaster species complex 总被引:14,自引:1,他引:13
Two regions of the genome, a 1-kbp portion of the zeste locus and a 1.1-
kbp portion of the yolk protein 2 locus, were sequenced in six individuals
from each of four species: Drosophila melanogaster, D. simulans, D.
mauritiana, and D. sechellia. The species and strains were the same as
those of a previous study of a 1.9-kbp region of the period locus. No
evidence was found for recent balancing or directional selection or for the
accumulation of selected differences between species. Yolk protein 2 has a
high level of amino acid replacement variation and a low level of
synonymous variation, while zeste has the opposite pattern. This contrast
is consistent with information on gene function and patterns of codon bias.
Polymorphism levels are consistent with a ranking of effective population
sizes, from low to high, in the following order: D. sechellia, D.
melanogaster, D.mauritiana, and D. simulans. The apparent species
relationships are very similar to those suggested by the period locus
study. In particular, D. simulans appears to be a large population that is
still segregating variation that arose before the separation of D.
mauritiana and D. sechellia. It is estimated that the separation of
ancestral D. melanogaster from the other species occurred 2.5-3.4 Mya. The
separations of D. sechellia and D. mauritiana from ancestral D. simulans
appear to have occurred 0.58- 0.86 Mya, with D. mauritiana having diverged
from ancestral D. simulans 0.1 Myr more recently than D. sechellia.
相似文献
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Arthur Jamison 《BMJ (Clinical research ed.)》1888,1(1435):1380-1381
7.
Characterization of the cDNA coding for mouse prothrombin and localization of the gene on mouse chromosome 2 总被引:6,自引:0,他引:6
S J Degen L A Schaefer C S Jamison S G Grant J J Fitzgibbon J A Pai V M Chapman R W Elliott 《DNA and cell biology》1990,9(7):487-498
A series of overlapping cDNAs coding for mouse prothrombin (coagulation factor II) have been isolated and the composite DNA sequence has been determined. The complete prothrombin cDNA is 1,987 bp in length [excluding the poly(A) tail] and codes for 18 bp of 5' untranslated sequence, an open reading frame coding for 618 amino acids, a stop codon, and a 3' untranslated region of 112 bp followed by a poly(A) tail. The translated amino acid sequence predicts a molecular weight of 66,087, which includes 10 residues of gamma-carboxyglutamic acid. There are five potential N-linked glycosylation sites. Mouse prothrombin is 81.4% and 77.3% identical to the human and bovine proteins, respectively. Comparison of the cDNA coding for mouse prothrombin to the human and bovine cDNAs indicates 79.9% and 76.5% identity, respectively. Amino acid residues important for the structure and function of human prothrombin are conserved in the mouse and bovine proteins. In the adult mouse and rat, prothrombin is primarily synthesized in the liver, where is constitutes 0.07% of total mRNA as determined by solution hybridization analysis. The genetic locus for mouse prothrombin, Cf-2, has been mapped using an interspecies backcross and DNA fragment differences between the two species. The prothrombin locus lies on mouse chromosome 2, 1.8 +/- 1.3 map units proximal to the catalase locus. The gene order in this region is Cen-Acra-Cf-2-Cas-1-A-Tel. This localization extends the proximal boundary of the known region of homology between mouse chromosome 2 and human chromosome 11p from Cas-1 about 2 map units toward the centromere. 相似文献
8.
J. Jamison J. Gilloteaux M. R. Nassiri C. C. Tsai J. Summers 《Nucleosides, nucleotides & nucleic acids》2013,32(6-7):1221-1222
Abstract Magnesium (Mg2+) potentiated the anti-vesicular stomatitis virus (VSV) activity of poly r(A-U) or poly r(G-C) and the anti-HIV-1 activity of poly r(A-U). Mg2+ did not affect the anti-VSV activity of poly (rI) ? poly (rC), poly (dA-dT) ? poly (dA-dT) or poly (dG-dC) ? poly (dG-dC). Modulation of one or more nuclear (nucleolar) processes of the host cell may be responsible for the synergistic antiviral activity. 相似文献
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