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991.
Epperly MW Epperly LD Niu Y Wang H Zhang X Franicola D Greenberger JS 《Radiation research》2007,168(5):560-566
We determined whether manganese superoxide dismutase (MnSOD)-plasmid liposome (PL) transfection of C57BL/ 6NHsd mouse bone marrow protected cells irradiated at room temperature (24 degrees C) or in the cryopreserved state. MnSOD-overexpressing hematopoietic progenitor 2C6 cells were radioresistant compared to the parent 32D cl 3 cells when irradiated frozen or at 24 degrees C. Fresh whole marrow from mice injected intravenously with MnSOD-PL prior to explant as well as explanted marrow single cell suspensions transfected in vitro were irradiated at 24 degrees C or -80 degrees C. In vivo or in vitro transfection of marrow with MnSOD-PL produced significant radiation protection of irradiated marrow progenitor cells compared to controls at 24 degrees C or -80 degrees C. (in vivo transfection D(0) 2.19 +/- 0.21 at 24 degrees C, D(0) 2.10 +/- 0.07 at -80 degrees C compared to control D(0) 1.56 +/- 0.06 or 1.66 +/- 0.04, P = 0.047 and 0.017 respectively; in vitro transfection D(0) 2.35 +/- 0.11 at 24 degrees C, D(0) 3.42 +/- 0.13 at -80 degrees C compared to D(0) 1.81 +/- 0.01 or 2.53 +/- 0.05, P = 0.0087 and 0.0026, respectively). Thus the MnSOD transgene product protects frozen marrow cells as well as marrow cells irradiated at 24 degrees C. 相似文献
992.
Li YL Niu SZ Dong YB Cui DQ Wang YZ Liu YY Wei MG 《TAG. Theoretical and applied genetics. Theoretische und angewandte Genetik》2007,115(1):129-140
Normal maize germplasm could be used to improve the grain yield of popcorn inbreds. Our first objective was to locate genetic
factors associated with trait variation and make first assessment on the efficiency of advanced backcross quantitative trait
locus (AB-QTL) analysis for the identification and transfer of favorable QTL alleles for grain yield components from the dent
corn inbred. A second objective was to compare the detection of QTL in the BC2F2 population with results using F2:3 lines of the same parents. Two hundred and twenty selected BC2F2 families developed from a cross between Dan232 and an elite popcorn inbred N04 were evaluated for six grain yield components
under two environments, and genotyped by means of 170 SSR markers. Using composite interval mapping (CIM), a total of 19 significant
QTL were detected. Eighteen QTL had favorable alleles contributed by the dent corn parent Dan232. Sixteen of these favorable
QTL alleles were not in the same or near marker intervals with QTL for popping characteristics. Six QTL were also detected
in the F2:3 population. Improved N04 could be developed from 210 and 208 families with higher grain weight per plant and/or 100-grain
weight, respectively, and 35 families with the same or higher popping expansion volume than N04. In addition, near isogenic
lines containing detected QTL (QTL-NILs) for grain weight per plant and/or 100-grain weight could be obtained from 12 families.
Our study demonstrated that the AB-QTL method can be applied to identify and manipulate favorable QTL alleles from normal
corn inbreds and combine QTL detection and popcorn breeding efficiently. 相似文献
993.
994.
Extraction of mechanical properties of articular cartilage from osmotic swelling behavior monitored using high frequency ultrasound 总被引:2,自引:0,他引:2
Articular cartilage is a biological weight-bearing tissue covering the bony ends of articulating joints. Negatively charged proteoglycan (PG) in articular cartilage is one of the main factors that govern its compressive mechanical behavior and swelling phenomenon. PG is nonuniformly distributed throughout the depth direction, and its amount or distribution may change in the degenerated articular cartilage such as osteoarthritis. In this paper, we used a 50 MHz ultrasound system to study the depth-dependent strain of articular cartilage under the osmotic loading induced by the decrease of the bathing saline concentration. The swelling-induced strains under the osmotic loading were used to determine the layered material properties of articular cartilage based on a triphasic model of the free-swelling. Fourteen cylindrical cartilage-bone samples prepared from fresh normal bovine patellae were tested in situ in this study. A layered triphasic model was proposed to describe the depth distribution of the swelling strain for the cartilage and to determine its aggregate modulus H(a) at two different layers, within which H(a) was assumed to be linearly dependent on the depth. The results showed that H(a) was 3.0+/-3.2, 7.0+/-7.4, 24.5+/-11.1 MPa at the cartilage surface, layer interface, and deep region, respectively. They are significantly different (p<0.01). The layer interface located at 70%+/-20% of the overall thickness from the uncalcified-calcified cartilage interface. Parametric analysis demonstrated that the depth-dependent distribution of the water fraction had a significant effect on the modeling results but not the fixed charge density. This study showed that high-frequency ultrasound measurement together with triphasic modeling is practical for quantifying the layered mechanical properties of articular cartilage nondestructively and has the potential for providing useful information for the detection of the early signs of osteoarthritis. 相似文献
995.
Nikkomycins are highly potent inhibitors of chitin synthase. The nikkomycin biosynthetic gene cluster has been cloned from
Streptomyces asochromogenes. Two cytochrome P450 monooxygenase genes (sanQ, sanH) and one ferredoxin gene (sanI) were found in the cluster. It was reported that SanQ is involved in the hydroxylation of l-His, a key step in 4-formyl-4-imidazolin-2-one base biosynthesis. Here, we have studied the function of sanH and sanI. Disruption of sanH abolished the production of nikkomycin X and Z, but it accumulated one dominant component nikkomycin Lx, which is the nikkomycin
X analog lacking the hydroxy group at the pyridyl residue. The sanI disruption mutant accumulated predominantly nikkomycin Lx in addition to nikkomycin X and Z. The nikkomycin production profile
of the sanH and sanI double disruption mutant was the same as that of the sanH disruption mutant. These results confirmed that SanH is essential for the hydroxylation of pyridyl residue in nikkomycin
biosynthesis of S. ansochromogenes and first demonstrated that SanI is an effective electron donor for SanH, but not for SanQ in vivo. 相似文献
996.
Niu Q Huang X Zhang L Lian L Li Y Li J Yang J Zhang K 《Applied microbiology and biotechnology》2007,75(1):141-148
Bacillus nematocida is a Gram-positive bacterium capable of killing nematodes. Our recent studies identified an extracellular serine protease
Bace16 in B. nematocida as a candidate of pathogenic factor in the infection against nematodes, which displayed a high similarity with the serine
protease family subtilisin BPN’, and the MEROPS ID is S08.034. To further confirm the roles that bace16 played in the mechanism of nematocidal pathogenesis, recombinant mature Bace16 (rm-Bace16) was expressed in Escherichia coli strain BL21 using pET-30 vector system. Bioassay experiments demonstrated that the purified recombinant protease had the
ability to degrade nematode cuticles and kill nematodes. In addition, a bace16 knockout mutant of B. nematocida constructed by homologous recombination showed considerably lower proteolytic activity and less than 50% nematocidal activity
than the wild-type strain. These results confirmed that Bace16 could serve as an important virulence factor during the infectious
process.
Qiuhong Niu and Xiaowei Huang contributed equally to this work. 相似文献
997.
Shaofeng H Shuben L Jiayin X Jianzhong N Chungu X Haidong T Wei T 《Bioscience, biotechnology, and biochemistry》2007,71(1):122-129
Methane monooxygenase hydroxylase was purified by chromatography and characterized by electrophoresis and spectroscopy. The molecular mass of hydroxylase was 201.3 KDa as determined by gel filtration, whereas the total molecular mass was 234 KDa as judged by SDS-PAGE. Structure study indicated that the enzyme is a homodimer structure, consisting of three subunits, designated alpha, beta, and gamma, with molecular masses of 58 KDa, 36 KDa, and 23 KDa respectively. IEF analysis indicated that the enzyme has a pI of 5.2. The UV-Vis spectrum of hydroxylase revealed an absorption peak near 281 nm and a weak shoulder peak around 395 nm-420 nm, and a fluorescence spectrum revealed an emission peak at 341.3 nm. Circular dichroism measurement indicated that hydroxylase mainly consists of alpha-helical regions. Finally, phylogenetic analysis indicated that this strain is very close to Methylosinus trichosporium OB3b. 相似文献
998.
Serum response factor micromanaging cardiogenesis 总被引:3,自引:0,他引:3
999.
1000.
Insulin sensitivity and inhibition by forskolin,dipyridamole and pentobarbital of glucose transport in three L6 muscle cell lines
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L6 skeletal muscle myoblasts stably overexpressing glucose transporter GLUT1 or GLUT4 with exofacial myc-epitope tags were characterized for their response to insulin. In clonally selected cultures, 2-deoxyglucose uptake into
L6-GLUT1myc myoblasts and myotubes was linear within the time of study. In L6-GLUT1myc and L6-GLUT4myc myoblasts, 100 nmol/L insulin treatment increased the GLUT1 content of the plasma membrane by 1.58±0.01 fold and the GLUT4
content 1.96±0.11 fold, as well as the 2-deoxyglucose uptake 1.53±0.09 and 1.86±0.17 fold respectively, all by a wortmannin-inhibitable
manner. The phosphorylation of Akt in these two cell lines was increased by insulin. L6-GLUT1myc myoblasts showed a dose-dependent stimulation of glucose uptake by insulin, with unaltered sensitivity and maximal responsiveness
compared with wild type cells. By contrast, the improved insulin responsiveness and sensitivity of glucose uptake were observed
in L6-GLUT4myc myoblasts. Earlier studies indicated that forskolin might affect insulin-stimulated GLUT4 translocation. A 65% decrease of
insulin-stimulated 2-deoxyglucose uptake in GLUT4myc cells was not due to an effect on GLUT4 mobilization to the plasma membrane, but instead on direct inhibition of GLUT4. Forskolin
and dipyridamole are more potent inhibitors of GLUT4 than GLUT1. Alternatively, pentobarbital inhibits GLUT1 more than GLUT4.
The use of these inhibitors confirmed that the overexpressed GLUT1 or GLUT4 are the major functional glucose transporters
in unstimulated and insulin-stimulated L6 myoblasts. Therefore, L6-GLUT1myc and L6-GLUT4myc cells provide a platform to screen compounds that may have differential effects on GLUT isoform activity or may influence
GLUT isoform mobilization to the cell surface of muscle cells. 相似文献