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261.
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263.
M. Iqbal Choudhary Saira Erum Muhammad Atif Rizwana Malik Naik Tameen Khan Atta-ur-Rahman 《Steroids》2011,76(12):1288-1296
Microbial transformation of (20S)-20-hydroxymethylpregna-1,4-dien-3-one (1) by four filamentous fungi, Cunninghamella elegans, Macrophomina phaseolina, Rhizopus stolonifer, and Gibberella fujikuroi, afforded nine new, and two known metabolites 2–12. The structures of these metabolites were characterized through detailed spectroscopic analysis. These metabolites were obtained as a result of biohydroxylation of 1 at C-6β, -7β, -11α, -14α, -15β, -16β, and -17α positions, except metabolite 2 which contain an O-acetyl group at C-22. These fungal strains demonstrated to be efficient biocatalysts for 11α-hydroxylation. Compound 1, and its metabolites were evaluated for the first time for their cytotoxicity against the HeLa cancer cell lines, and some interesting results were obtained. 相似文献
264.
An efficient and facile synthesis of 17-chalconyl derivatives of pregnenolone and their evaluation as antimicrobial agents against various microbial strains is reported. The scheme involves the transformation of the starting pregnenolone acetate into pregnenolone, conversion of pregnenolone to the corresponding chalcone derivatives. The compounds 3a–3j showed significant antimicrobial activity against all microbial strains used for testing. 相似文献
265.
Raham Sher Khan Syed Sartaj Alam Iqbal Munir Pejman Azadi Ikuo Nakamura Masahiro Mii 《Plant Cell, Tissue and Organ Culture》2011,106(1):11-20
The presence of marker genes conferring antibiotic or herbicide resistance in transgenic plants has been a controversial issue
and a serious problem for their public acceptance and commercialization. The MAT (multi-auto-transformation) vector system
has been one of the strategies developed to excise the selection marker gene and produce marker-free transgenic plants. In
an attempt to produce transgenic marker-free Petunia hybrida plants resistant to Botrytis cinerea (gray mold), we used the ipt gene as a selectable marker gene and the wasabi defensin (WD) gene, isolated from Wasabia japonica (a Japanese horseradish which has been a potential source of antimicrobial proteins), as a gene of interest. The WD gene was cloned from the binary vector, pEKH-WD, to an ipt-type MAT vector, pMAT21, by gateway cloning technology and transferred to Agrobacterium
tumefaciens strain EHA105. Infected leaf explants of P.
hybrida were cultured on hormone- and antibiotic-free MS medium. Extreme shooty phenotype (ESP)/ipt shoots were produced by the explants infected with the pMAT21-WD. The same antibiotic- and hormone-free MS medium was used in subcultures of the ipt shoots. Ipt shoots subsequently produced morphologically normal shoots. Molecular analyses of genomic DNA from the transgenic plants
confirmed the integration of the gene of interest and excision of the selection marker. Expression of the WD gene was confirmed by northern blot and western blot analyses. A disease resistance assay of the marker-free transgenic plants
exhibited enhanced resistance against B. cinerea strain 40 isolated from P. hybrida. 相似文献
266.
Rizwan Rasheed A. Wahid M. Farooq Iqbal Hussain Shahzad M. A. Basra 《Plant Growth Regulation》2011,65(1):35-45
High temperature strongly hampers the plant growth particularly at early growth stages. In this study, changes in some physiological
and anatomical characteristics and possibility of mitigating the adversities of heat stress by soaking sugarcane nodal buds
in 20 mM proline and glycinebetaine (GB) solutions have been explored. Heat stress reduced the rate of bud sprouting nonetheless
soaking the setts in proline followed by GB was beneficial. In addition, heat stress reduced the bud fresh and dry weights,
generated H2O2, reduced the tissue levels of K+ and Ca2+, while increased the osmolytes synthesis in a time course manner. Heat stress also delayed the emergence and expansion of
new bud leaves, by restricting the number and area of mesophyll cells. It also caused poor and aberrant development and diffused
appearance of mesophyll cells and vascular bundles in the bud leaves. However, soaking of buds in proline and GB solutions
substantially reduced the H2O2 production, improved the accumulation of soluble sugars and protected the developing tissues from heat stress effects; although
proline was more effective than GB. Correlations of various attributes indicated that soaking in GB and proline restricted
the H2O2 generation, improved K+ and Ca2+ contents, and increased the concentrations of free proline, GB and soluble sugars eventually improving the heat tolerance
of buds. Cost-benefit analysis showed that, considering increase in sprouting of buds, soaking in 20 mM solution of both osmoprotectants
is economical. 相似文献
267.
Amber Afroz Zubeda Chaudhry Umer Rashid Ghulam Muhammad Ali Farhat Nazir Javaid Iqbal Muhammad Rashid Khan 《Plant Cell, Tissue and Organ Culture》2011,104(2):227-237
To enhance bacterial wilt resistance in tomato plants and simplify the protocol of Agrobacterium tumefaciens mediated gene transfer, parameters affecting transformation efficiency in tomato have been optimized. A. tumefaciens strain EHA101, harboring a recombinant binary expression vector pTCL5 containing the Xa21 gene under the control of the CaMV 35S promoter was used for transformation. Five cultivars of tomato (Rio Grande, Roma,
Pusa Ruby Pant Bahr and Avinash) were tested for transformation. Transformation efficiency was highly dependent on preculture
of the explants with acetosyringone, acetosyringone in co-cultivation media, shoot regeneration medium and pre-selection after
co-cultivation without selective agent. One week of pre-selection following selection along with 400 μM acetosyringone resulted
in 92.3% transient GUS expression efficiency in Rio Grande followed by 90.3% in Avinash. The presence and integration of the
Xa21 gene in putative transgenic plants was confirmed by polymerase chain reaction (PCR) and Southern blot analyses with 4.5–42.12%
PCR-positive shoots were obtained for Xa21 and hygromycin genes, respectively. Transgenic plants of the all lines showed resistance to bacterial wilt. T1 plants (resulting from self-pollination of transgenic plants) tested against Pseudomonas solanacearum inoculation in glasshouse, showed Mendelian segregation. 相似文献
268.
The present study was conducted to examine the changes in some key metabolites in drought-stressed sunflower plants supplied
with glycine betaine externally. Imposition of drought stress at the vegetative or reproductive growth stages decreased the
plant dry matter production and increased the accumulation of organic solutes (glycine betaine, proline, soluble proteins,
free amino acids and soluble sugars) in two sunflower lines, i.e., Glushan-98 and Suncross. In general, decrease in dry matter
production and increase in the endogenous levels of organic solutes, were more pronounced when drought stress applied at the
vegetative stage than at the reproductive stage. Glycine betaine applied as a pre-sowing seed treatment was not found to be
effective in reducing the negative effects of drought stress in sunflower plants. Foliar application of GB further enhanced
the leaf endogenous levels of GB, soluble proteins and total soluble sugars in drought stressed plants without exerting any
negative effects on other osmotica. However, this GB-induced increase in endogenous levels of organic solutes was found to
be not associated with plant dry matter production under stress conditions. 相似文献
269.
Uzma Majid Mahmooduzzafar Tariq Omar Siddiqi Muhammad Iqbal 《Acta Physiologiae Plantarum》2014,36(2):307-314
Seeds of Cassia angustifolia Vahl., treated with various concentrations (0, 0.1, 0.15, 0.2 and 0.25 %) of Mancozeb, a broad-spectrum contact fungicide, were sown in field conditions to study the effect of the treatments on lipid peroxidation, proline accumulation and modulation of antioxidant system of seedlings obtained. Significant increase over the control was observed in treated plants for thiobarbituric acid-reactive substances content (up to 207 %), proline content (96 %) and total glutathione content (144 %), whereas the total ascorbate content decreased by 44 %. Increased enzymatic activity was recorded for ascorbate peroxidase (63 %), glutathione reductase (154 %) and superoxide dismutase (109 %), whereas catalase activity decreased by 58 % with 0.25 % Mancozeb treatment. The changes observed were dose-dependent, showing a strong correlation with the level of treatment. 相似文献
270.
Nida Iram Muhammad Salahuddin Shah Fouzia Ismat Mudasser Habib Mazhar Iqbal S. Samar Hasnain Moazur Rahman 《Applied microbiology and biotechnology》2014,98(4):1691-1701
Newcastle disease virus (NDV) is an infectious agent of a large variety of birds, including chicken, which poses a real threat to the agriculture industry. Matrix (M) proteins of NDV and many other viruses perform critical functions during viral assembly and budding from the host cell. M-proteins are well conserved and therefore are potential targets for antiviral therapies. To validate this, we expressed the NDV M-protein in its native form in Saccharomyces cerevisiae and in inclusion bodies in Escherichia coli. Proper refolding of the recombinant protein produced in E. coli was verified using circular dichroism and infrared spectroscopies and electron microscopy. Immunization of chickens with the NDV M-protein elicited significant serum antibody titers. However, the antibodies conferred little protection against the ND following lethal viral challenges. We conclude that the M-protein is not exposed on the surface of the host cell or the virus at any stage during its life cycle. We discuss how the conserved M-protein can further be exploited as an antiviral drug target. 相似文献