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381.
Isabelle Ourliac-Garnier Anaïs Poulet Razan Charif Simon Amiard Frédérique Magdinier Keyvan Rezaï Eric Gilson Marie-Josèphe Giraud-Panis Sophie Bombard 《Journal of biological inorganic chemistry》2010,15(5):641-654
Telomeres, the nucleoprotein complexes located at the ends of chromosomes, are involved in chromosome protection and genome
stability. Telomeric repeat binding factor 1 (TRF1) and telomeric repeat binding factor 2 (TRF2) are the two telomeric proteins
that bind to duplex telomeric DNA through interactions between their C-terminal domain and several guanines of the telomeric
tract. Since the antitumour drug cisplatin binds preferentially to two adjacent guanines, we have investigated whether cisplatin
adducts could affect the binding of TRF1 and TRF2 to telomeric DNA and the property of TRF2 to stimulate telomeric invasion,
a process that is thought to participate in the formation of the t-loop. We show that the binding of TRF1 and TRF2 to telomeric
sequences selectively modified by one GG chelate of cisplatin is markedly affected by cisplatin but that the effect is more
drastic for TRF2 than for TRF1 (3–5-fold more sensitivity for TRF2 than for TRF1). We also report that platinum adducts cause
a decrease in TRF2-dependent stimulation of telomeric invasion in vitro. Finally, in accordance with in vitro data, analysis
of telomeric composition after cisplatin treatment reveals that 60% of TRF2 dissociate from telomeres. 相似文献
382.
Karimi M Carl JL Loftin S Perlmutter JS 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2006,836(1-2):120-123
Plasma measurements of levodopa and its major metabolites including dopamine and 3-O-methyldopa have been limited by cumbersome methods and poor sensitivity within relatively narrow ranges of plasma levels. We now report a modification of an HPLC method that permits concomitant measurements of a wide range of concentrations of levodopa, dopamine (DA), carbidopa, 3-O-methyldopa (3-OMD) and 3,4-dihydroxyphenyl acetic acid (DOPAC) from one HPLC injection. The recoveries ranged from 77 to 107% with an intra-day precision around 5% (CV) and inter-day CV's about 10-20%. This validated method will simplify pharmacokinetic studies of levodopa and its metabolites for mechanistic studies or therapeutic clinical monitoring which play a crucial role in development of strategies to prolong motor benefits from individual doses and reduce involuntary movements called dykinesias. 相似文献
383.
Efficient mouse transgenesis using Gateway-compatible ROSA26 locus targeting vectors and F1 hybrid ES cells
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Omar Nyabi Michael Naessens Katharina Haigh Agnieszka Gembarska Steven Goossens Marion Maetens Sarah De Clercq Benjamin Drogat Lieven Haenebalcke Sonia Bartunkova Ilse De Vos Bram De Craene Mansour Karimi Geert Berx Andras Nagy Pierre Hilson Jean-Christophe Marine Jody J. Haigh 《Nucleic acids research》2009,37(7):e55
The ability to rapidly and efficiently generate reliable Cre/loxP conditional transgenic mice would greatly complement global high-throughput gene targeting initiatives aimed at identifying gene function in the mouse. We report here the generation of Cre/loxP conditional ROSA26-targeted ES cells within 3–4 weeks by using Gateway® cloning to build the target vectors. The cDNA of the gene of interest can be expressed either directly by the ROSA26 promoter providing a moderate level of expression or by a CAGG promoter placed in the ROSA26 locus providing higher transgene expression. Utilization of F1 hybrid ES cells with exceptional developmental potential allows the production of germ line transmitting, fully or highly ES cell-derived mice by aggregation of cells with diploid embryos. The presented streamlined procedures accelerate the examination of phenotypical consequences of transgene expression. It also provides a unique tool for comparing the biological activity of polymorphic or splice variants of a gene, or products of different genes functioning in the same or parallel pathways in an overlapping manner. 相似文献
384.
The aims of the present study were to evaluate if seasonality in semen characteristics and plasma testosterone concentrations exist in Markhoz male goats. Ten Markhoz (Angora) bucks were housed and fed according to standard recognized practices. During the observation period, semen was collected monthly with the aid of an electro-ejaculator and examined microscopically immediately after collection. Physical parameters of semen and the semen index were recorded. Blood samples were also taken monthly throughout the observation period and the plasma testosterone concentration monitored. Bucks demonstrated a higher semen quality (P < 0.05) in autumn and summer (semen index of 965 × 106 and 752 × 106 ml−1, respectively), compared to spring and winter (semen index of 606 × 106 and 512 × 106, respectively). This coincided with a higher (P < 0.05) plasma testosterone concentration in autumn and summer (8.1 and 10.1 ng ml−1, respectively), compared to that obtained in spring (3.0 ng ml−1) and winter (2.5 ng ml−1). During autumn and summer, the ejaculate volume (average of 1.2 and 1.0 ml), sperm output (1159 × 106 and 1005 × 106 sperm ml−1), sperm mass motility (4.2 and 4.3), sperm progressive motility (83.9 and 82.0%) and percentage live sperm (90.7 and 88.2%, respectively) of the bucks were higher (P < 0.05) than in the spring (0.6 ml, 880 × 106 sperm ml−1, 3.3, 71.5% and 80.2%) and winter (0.7 ml, 863 × 106 sperm ml−1, 4.0, 71.5% and 84.9%, respectively). During autumn and summer, the percentage of sperm abnormalities (5.0 and 9.2%) was significantly lower than that in spring (12.9%) and winter (11.2%). The semen pH was slightly alkaline being significantly (P < 0.05) lower in the autumn (7.1) than in spring (7.3). Data showed season of the year to influence all semen parameters evaluated—indicating that optimal buck performance may be obtained in late summer and autumn. It can thus be said that Markhoz bucks have distinct seasonal spermatogenic activity, with poorer semen characteristics being recorded during winter and spring. This may be a critical obstacle when implementing an intensive breeding system of three kidding seasons in 2 years, with natural mating being implemented. 相似文献
385.
Patrik R. Lennartsson Keikhosro Karimi Lars Edebo Mohammad J. Taherzadeh 《Journal of biotechnology》2009,143(4):255-261
The dimorphic fungus Mucor indicus was grown in different forms classified as purely filamentous, mostly filamentous, mostly yeast-like and purely yeast-like, and the relationship between morphology and metabolite production, inhibitor tolerance and the cell wall composition was investigated. Low concentrations of spores in the inoculum with subsequent aeration promoted filamentous growth, whereas higher spore concentrations and anaerobic conditions promoted yeast-like growth. Ethanol was the main metabolite with glycerol next under all conditions tested. The yields of ethanol from glucose were between 0.39 and 0.42 g g−1 with productivities of 3.2–5.0 g l−1 h−1. The ethanol productivity of mostly filamentous cells was increased from 3.9 to 5.0 g l−1 h−1 by the presence of oxygen, whereas aeration of purely yeast-like cells showed no such effect. All growth forms were able to tolerate 4.6 g l−1 furfural and 10 g l−1 acetic acid and assimilate the sugars, although with different consumption rates. The cell wall content of the fungus measured as alkali insoluble materials (AIM) of the purely yeast-like cells was 26% of the biomass, compared to 8% of the pure filaments. However, the chitosan concentration of the filaments was 29% of the AIM, compared to 6% of the yeast-like cells. 相似文献
386.
Sylvester Elikana Anami Allan Jalemba Mgutu Catherine Taracha Griet Coussens Mansour Karimi Pierre Hilson Mieke Van Lijsebettens Jesse Machuka 《Plant Cell, Tissue and Organ Culture》2010,102(3):285-295
In Latin America and sub-Saharan Africa, tropical maize (Zea mays L.) is a major crop for human consumption. To cope with the increasing population and changing environment, there is a need
for improving tropical maize germplasm. As part of a biotechnological approach, efficient in vitro regeneration of two tropical
maize inbred lines (CML216 and CML244) was established. A number of parameters were optimized, such as age of the immature
embryos, plant media and growth regulator concentration. After 6 weeks of culture, somatic embryos that had already reached
the coleoptilar stage produced shoots after light induction and developed into fertile plants after acclimation in the soil.
The callus induction frequencies and somatic embryo-derived plantlet formation were higher when cultured with the Linsmaier
and Skoog medium than those with the Chu’s N6 basal medium. Regeneration of tropical maize shoots depended on the 2,4-dichlorophenoxyacetic
acid (2,4-D) concentration at the callus initiation stage from immature embryos. The recalcitrance of the tropical maize inbred
line TL26 to in vitro regeneration was overcome in a single-cross hybrid with the CML216 and CML244 genotypes. Remarkably,
tropical maize somatic embryos were formed at the abaxial side of the scutellum facing the medium, probably from the axis
of the immature embryos, as shown by histological sections. Upon co-cultivation, agrobacteria transiently expressed their
intronless β-glucuronidase-encoding gene at the embryogenic tissue, but not with an intron-containing gene, suggesting that
virulence genes are induced in Agrobacterium, but that subsequent steps in the T-DNA transfer are inhibited. 相似文献
387.
388.
Laleh Shariati Majid Validi Mohammad Amin Tabatabaiefar Ali Karimi Mohammad Reza Nafisi 《Current microbiology》2010,61(6):520-524
Methicillin-resistant Staphylococcus aureus (MRSA) is a nosocomial pathogen. Our main objective was to compare oxacillin disk test, oxacillin E-test, and oxacillin agar screen for detection of methicillin resistance in S. aureus, using real-time PCR for mecA as the “gold standard” comparison assay. 196 S. aureus isolates were identified out of 284 Staphylococcus isolates. These isolates were screened for MRSA with several methods: disk diffusion, agar screen (6.0 μg/ml), oxacillin E-test, and real-time PCR for detection of mecA gene. Of the 196 S. aureus isolates tested, 96 isolates (49%) were mecA-positive and 100 isolates (51%) mecA-negative. All methods tested had a statistically significant agreement with real-time PCR. E-test was 100% sensitive and specific for mecA presence. The sensitivity and specificity of oxacillin agar screen method were 98 and 99%, respectively and sensitivity and specificity of oxacillin disk diffusion method were 95 and 93%, respectively. In the present study, oxacillin E-test is proposed as the best phenotypic method. For economic reasons, the oxacillin agar screen method (6.0 μg/ml), which is suitable for the detection of MRSA, is recommended due to its accuracy and low cost. 相似文献
389.
The pathway of bacterial ribosome recycling following translation termination has remained obscure. Here, we elucidate two essential steps and describe the roles played by the three translation factors EF-G, RRF, and IF3. Release factor RF3 is known to catalyze the dissociation of RF1 or RF2 from ribosomes after polypeptide release. We show that the next step is dissociation of 50S subunits from the 70S posttermination complex and that it is catalyzed by RRF and EF-G and requires GTP hydrolysis. Removal of deacylated tRNA from the resulting 30S:mRNA:tRNA posttermination complex is then necessary to permit rapid 30S subunit recycling. We show that this step requires initiation factor IF3, whose role was previously thought to be restricted to promoting specific 30S initiation complex formation from free 30S subunits. 相似文献
390.
To understand the response of potato to salt stress, antioxidant enzyme activities and ion content were analyzed for a sensitive and a tolerant cultivar. Nodal cuttings of the tolerant cultivar, Kennebec, and the sensitive cultivar, Concord, were exposed to media without or with 30, 60, 90 or 120 mmol/L NaCI for 4 weeks. On exposure to NaCI, the length and fresh and dry weight of both shoots and roots of Concord showed greater decrease than those of Kennebec. The decrease in shoot growth was more severe than that of the root for both cultivars. The K^+ content of shoots and roots of both cultivars was reduced in a dose-dependent manner by exposure to NaCl; the Na^+ content increased. Activities of ascorbate peroxidase, catalase and glutathione reductase were increased in NaCl-exposed shoots of Kennebec; the corresponding activities in NaCI-exposed shoots of Concord were decreased. Roots of both cultivars showed similar changes in the activities of these enzymes on exposure to NaCI. These studies established that enzyme activities in Concord shoots are inversely related to the NaCI concentration, whereas those in Kennebec do not show a dose dependency, which is also the case for the roots of both cultivars. Our findings suggest that an increase in activity of antioxidant enzymes, such as ascorbate peroxidase, catalase and glutathione reductase, can contribute to salt tolerance in Kennebec, a salt resistant cultivar of potato. 相似文献