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排序方式: 共有113条查询结果,搜索用时 31 毫秒
41.
Veronika I. Zabarovska Rinat Z. Gizatullin Ali N. Al-Amin Raf Podowski Alexei I. Protopopov Sven Lfdahl Claes Wahlestedt Gsta Winberg Vladimir I. Kashuba Ingemar Ernberg Eugene R. Zabarovsky 《Nucleic acids research》2002,30(2):e6
We describe here an efficient strategy for simultaneous genome mapping and sequencing. The approach is based on physically oriented, overlapping restriction fragment libraries called slalom libraries. Slalom libraries combine features of general genomic, jumping and linking libraries. Slalom libraries can be adapted to different applications and two main types of slalom libraries are described in detail. This approach was used to map and sequence (with ~46% coverage) two human P1-derived artificial chromosome (PAC) clones, each of ~100 kb. This model experiment demonstrates the feasibility of the approach and shows that the efficiency (cost-effectiveness and speed) of existing mapping/sequencing methods could be improved at least 5–10-fold. Furthermore, since the efficiency of contig assembly in the slalom approach is virtually independent of length of sequence reads, even short sequences produced by rapid, high throughput sequencing techniques would suffice to complete a physical map and a sequence scan of a small genome. 相似文献
42.
A V Ryndich V I Kashuba V M Kavsan S V Zubak I Hlozanek 《Molekuliarnaia biologiia》1989,23(5):1355-1363
For the elucidation of the molecular basis of RSV adaptation to conditionally permissive host from the genome library of duck embryo fibroblasts, transformed by Rous sarcoma virus in 30 passages on these cells, recombinant bacteriophages that include provirus sequences, were obtained. Complete and transformation-defective proviruses were characterized, nucleotide sequences of their env-genes were compared with their counterparts the original RSV (Pr-RSV-C) and with viruses of other subgroups (A, B, D and E). The possible relation of the revealed changes in domains coding gp85 and gp37, with the changes of chicken RSV characteristics during adaptation to duck cells is discussed. 相似文献
43.
The host range of retroviruses is rather complex and specific. It is controlled by the products of viral structural genes that interact with the determinants both on the surface and within the cell. The possibility to infect and transform duck embryo fibroblasts is shown for the Prague strain of chicken Rous sarcoma virus (subgroup C), though virus production in these cells is restricted. However, after the 6th passage the "adapted" virus gave the titre practically the same as it was for chicken embryo fibroblasts. Provirus of RSV adapted to the duck embryo fibroblasts and integrated into host DNA was isolated from the library of nucleotide sequences of duck embryo fibroblasts transformed by this virus. The nucleotide sequence of such provirus was determined. The alterations in gp85 coding region of the env gene which proved to be the result of recombination with endogeneous RAV-0 sequences were shown. The formation of viral particles with rather high titre was induced by the proviral transfection on both chicken and duck embryo fibroblasts. The contribution of the revealed alterations in the genome of transformation active virus and possible participation of its td mutant in the adaptation to the new host are discussed. 相似文献
44.
Tracey?N?Wilkinson Terence?P?Speed Geoffrey?W?Tregear Ross?AD?BathgateEmail author 《BMC evolutionary biology》2005,5(1):14
Background
The relaxin-like peptide family belongs in the insulin superfamily and consists of 7 peptides of high structural but low sequence similarity; relaxin-1, 2 and 3, and the insulin-like (INSL) peptides, INSL3, INSL4, INSL5 and INSL6. The functions of relaxin-3, INSL4, INSL5, INSL6 remain uncharacterised. The evolution of this family has been contentious; high sequence variability is seen between closely related species, while distantly related species show high similarity; an invertebrate relaxin sequence has been reported, while a relaxin gene has not been found in the avian and ruminant lineages. 相似文献45.
Rezk NL Crutchley RD Kashuba AD 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2005,822(1-2):201-208
An accurate, sensitive and simple reverse-phase (RP) high-performance liquid chromatography (HPLC) assay for the simultaneous quantitative determination of emtricitabine and tenofovir in human blood plasma is described. Using 200 microL of plasma and BOND ELUT-C18 Varian columns, the solid phase extraction (SPE) method results in a clean baseline and high extraction efficiencies (100% for emtricitabine and 98.6% for tenofovir). An Atlantistrade mark dC-18 analytical column is used along with an 18 min linear gradient elution of phosphate buffer (pH 5.7) and methanol to provide sharp peaks for emtricitabine at 280 nm, tenofovir at 259 nm, and the internal standard 2',3'didoxyuridine (DDU) at 262 nm. The method was validated over the range of 10-10,000 ng/mL for both analytes, and is accurate (average accuracies of three different concentrations ranged from 98 to 105% for emtricitabine and 97 to 103% for tenofovir) and precise (within- and between-day precision ranged from 1.7 to 3.7% and 3.7 to 5.2%, respectively). This method is suitable for use in clinical pharmacokinetic studies and is nimble enough for therapeutic drug monitoring. 相似文献
46.
47.
Paul Dijkstra AD. H. M. C. Schapendonk KO. Groenwold Marinus Jansen Siebe C. Van De Geijn 《Global Change Biology》1999,5(5):563-576
Winter wheat was grown at ambient and elevated (ambient plus 350 μL L–1) CO2 concentrations in open top chambers and in field-tracking sun-lit climatized enclosures (elevated is 718 μL L–1). There was no significant effect of CO2 concentration on sheath, leaf and root biomass and leaf area in the early spring (January to April). 24-h canopy CO2 exchange rate (CCER) was not significantly affected either. However, elevated CO2 concentration increased CCER at midday, decreased evapotranspiration rate and increased instantaneous water-use-efficiency during early spring. Leaf, sheath and root nitrogen concentration per unit dry weight decreased and nonstructural carbohydrate concentration increased under elevated CO2, and N-uptake per unit ground area decreased significantly (– 22%) towards the end of this period. These results contrast with results from the final harvest, when grain yield and biomass were increased by 19% under elevated CO2. N concentration per dry weight was reduced by 5%, but N-uptake per unit ground area was significantly higher (+ 11%) for the elevated CO2 treatment. 24-h and midday-CCER increased significantly more in late spring (period of 21 April to 30 May) (respectively by + 40% and 53%) than in the early spring (respectively 5% and 19%) in response to elevated CO2. Midday evapotranspiration rate was reduced less by elevated CO2 in the late spring (– 13%) than in early spring (– 21%). The CO2 response of midday and 24-h CCER decreased again (+ 27% and + 23% resp.) towards the end of the growing season. We conclude that the low response to CO2 concentration during the early spring was associated with a growth-restriction, caused by low temperature and irradiance levels. The reduction of nitrogen concentration, the increase of nonstructural carbohydrate, and the lower evapotranspiration indicated that CO2 did have an effect towards the end of early spring, but not on biomass accumulation. Regression analysis showed that both irradiance and temperature affected the response to CO2. 相似文献
48.
Ca2+, annexins, and GTP modulate exocytosis from maize root cap protoplasts 总被引:3,自引:0,他引:3
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Protoplasts isolated from root cap cells of maize were shown to secrete fucose-rich polysaccharides and were used in a patch-clamp study to monitor changes in whole-cell capacitance. Ca2+ was required for exocytosis, which was measured as an increase in cell capacitance during intracellular dialysis with Ca2+ buffers via the patch pipette. Exocytosis was stimulated significantly by small increases above normal resting [Ca2+]. In the absence of Ca2+, protoplasts decreased in size. In situ hybridization showed significant expression of the maize annexin p35 in root cap cells, differ-entiating vascular tissue, and elongating cells. Dialysis of protoplasts with maize annexins stimulated exocytosis at physiological [Ca2+], and this could be blocked by dialysis with antibodies specific to maize annexins. Dialysis with milli-molar concentrations of GTP strongly inhibited exocytosis, causing protoplasts to decrease in size. GTPgammaS and GDPbetaS both caused only a slight inhibition of exocytosis at physiological Ca2+. Protoplasts were shown to internalize plasma membrane actively. The results are discussed in relation to the regulation of exocytosis in what is usually considered to be a constitutively secreting system; they provide direct evidence for a role of annexins in exocytosis in plant cells. 相似文献
49.
CEES GRASHOFF † PAUL DIJKSTRA † SANDERINE NONHEBEL ‡ AD H.C.M. SCHAPENDONK† SIEBE C. VAN DE GEIJN† 《Global Change Biology》1995,1(6):417-428
The effect of elevated [CO2] on the productivity of spring wheat, winter wheat and faba bean was studied in experiments in climatized crop enclosures in the Wageningen Rhizolab in 1991–93. Simulation models for crop growth were used to explore possible causes for the observed differences in the CO2 response. Measurements of the canopy gas exchange (CO2 and water vapour) were made continuously from emergence until harvest. At an external [CO2] of 700 μmol mol?1 Maximum Canopy CO2 Exchange Rate (CCERmax) at canopy closure was stimulated by 51% for spring wheat and by 71% for faba bean. At the end of the growing season, above ground biomass increase at 700 μmol mol?1 was 58% (faba bean), 35% (spring wheat) and 19% (winter wheat) and the harvest index did not change. For model exploration, weather data sets for the period 1975-88 and 1991–93 were used, assuming adequate water supply and [CO2] at 350 and 700 μmol mol?1. For spring wheat the simulated responses (35–50%) were at the upper end of the experimental results. In agreement with experiments, simulations showed smaller responses for winter wheat and larger responses for faba bean. Further model explorations showed that this differential effect in the CO2 response may not be primarily due to fundamental physiological differences between the crops, but may be at least partly due to differences in the daily air temperatures during comparable stages of growth of these crops. Simulations also showed that variations between years in CO2 response can be largely explained by differences in weather conditions (especially temperature) between growing seasons. 相似文献
50.
Economic effectiveness of vaccination against measles in an agricultural region of the Ukrainian SSR has been studied. At the period preceding vaccination expenses for each measles patient in the country were three times as low as those in towns. At the period of vaccination a considerable decrease in expenses covering the payment of sick-leave certificates given to mothers taking care of their sick children, in losses connected with absenteeism, in expenses for gamma globulin prophylaxis and the hospital treatment and outpatient servicing of measles patients was observed due to the sharp drop of the total morbidity rate and the increased number of school children among measles patients. In urban and rural areas the equalization of expenses for each patient occurred. In spite of increased expenses for each measles patient, the considerable economy of sums spent for controlling measles was achieved: about 70,000 rubles per annum. 相似文献