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191.
Mohammad Babar Ali Serida Khatun Eun-Joo Hahn Kee-Yoeup Paek 《Plant Growth Regulation》2006,49(2-3):137-146
Effects of three levels of photosynthetic photon flux (PPF: 60, 160 and 300 μmol m−2s−1) were investigated in one-month-old Phalaenopsis plantlets acclimatised ex vitro. Optimal growth, chlorophyll and carotenoid concentations, and a high carotenoid:chlorophyll a ratio were obtained at 160 μmol m−2s−1, while net CO2 assimilation (A), stomatal conductance (g), transpiration rate (E) and leaf temperature peaked at 300 μmol m−2s−1, indicating the ability of the plants to grow ex vitro. Adverse effects of the highest PPF were reflected in loss of chlorophyll, biomass, non-protein thiol and cysteine, but increased proline. After acclimatisation, glucose-6-phosphate dehydrogenase, shikimate dehydrogenase, phenylalanine ammonia-lyase (PAL) and cinnamyl alcohol dehydrogenase (CAD) increased, as did lignin. Peroxidases (POD), which play an important role in lignin synthesis, were induced in acclimatised plants. Polyphenol oxidase (PPO) and β-glucosidase (β-GS) activities increased to a maximum in acclimatised plants at 300 μmol m−2s−1. A positive correlation between PAL, CAD activity and lignin concentration was observed, especially at 160 and 300 μmol m−2s−1. The study concludes that enhancement of lignin biosynthesis probably not only adds rigidity to plant cell walls but also induces defence against radiation stress. A PPF of 160 μmol m−2s−1was suitable for acclimatisation when plants were transferred from in vitro conditions. 相似文献
192.
Lee BJ Kwon SJ Kim SK Kim KJ Park CJ Kim YJ Park OK Paek KH 《Biochemical and biophysical research communications》2006,351(2):405-411
Two-dimensional gel electrophoresis (2-DE) was applied for the screening of Tobacco mosaic virus (TMV)-induced hot pepper (Capsicum annuum cv. Bugang) nuclear proteins. From differentially expressed protein spots, we acquired the matched peptide mass fingerprint (PMF) data, analyzed by MALDI-TOF MS, from the non-redundant hot pepper EST protein FASTA database using the VEMS 2.0 software. Among six identified nuclear proteins, the hot pepper 26S proteasome subunit RPN7 (CaRPN7) was subjected to further study. The level of CaRPN7 mRNA was specifically increased during incompatible TMV-P(0) interaction, but not during compatible TMV-P(1.2) interaction. When CaRPN7::GFP fusion protein was targeted in onion cells, the nuclei had been broken into pieces. In the hot pepper leaves, cell death was exacerbated and genomic DNA laddering was induced by Agrobacterium-mediated transient overexpression of CaPRN7. Thus, this report presents that the TMV-induced CaRPN7 may be involved in programmed cell death (PCD) in the hot pepper plant. 相似文献
193.
Evolution of variants of yeast site-specific recombinase Flp that utilize native genomic sequences as recombination target sites 总被引:2,自引:0,他引:2
Bolusani S Ma CH Paek A Konieczka JH Jayaram M Voziyanov Y 《Nucleic acids research》2006,34(18):5259-5269
As a tool in directed genome manipulations, site-specific recombination is a double-edged sword. Exquisite specificity, while highly desirable, makes it imperative that the target site be first inserted at the desired genomic locale before it can be manipulated. We describe a combination of computational and experimental strategies, based on the tyrosine recombinase Flp and its target site FRT, to overcome this impediment. We document the systematic evolution of Flp variants that can utilize, in a bacterial assay, two sites from the human interleukin 10 gene, IL10, as recombination substrates. Recombination competence on an end target site is acquired via chimeric sites containing mixed sequences from FRT and the genomic locus. This is the first time that a tyrosine site-specific recombinase has been coaxed successfully to perform DNA exchange within naturally occurring sequences derived from a foreign genomic context. We demonstrate the ability of an Flp variant to mediate integration of a reporter cassette in Escherichia coli via recombination at one of the IL10-derived sites. 相似文献
194.
Sheran HW Law Rudolf SS Wu Patrick KS Ng Richard MK Yu Richard YC Kong 《BMC molecular biology》2006,7(1):15-13
Background
Hypoxia-inducible factors (HIFs) are involved in adaptive and survival responses to hypoxic stress in mammals. In fish, very little is known about the functions of HIFs. 相似文献195.
Human seven-in-absentia (SIAH)-interacting protein (SIP) is a component of the E3 ligase complex targeting beta-catenin for destruction. Arabidopsis has one SIP protein (AtSIP) with 32% amino acid sequence identity to SIP. To investigate the functions of AtSIP, we isolated an atsip knockout mutant, and generated transgenic plants overexpressing AtSIP. The growth rates and morphologies of the atsip and transgenic plants were indistinguishable from those of wild type. However, atsip plants were more susceptible to Pseudomonas syringae infection, and the transgenic plants overexpressing AtSIP were more resistant. Consistent with this, RNA blot analysis showed that the AtSIP gene is strongly induced by wounding and hydrogen peroxide treatment. In addition, when plants were infected with P. syringae, AtSIP was transiently induced prior to PR-1 induction. These observations show that Arabidopsis AtSIP plays a role in resistance to pathogenic infection. 相似文献
196.
Chun-Hua Wu Yaser Hassan Dewir Eun-Joo Hahn Kee-Yoeup Paek 《Journal of Plant Biology》2006,49(3):193-199
We investigated different concentrations of auxins (1AA, IBA, NAA), the strength of the MS medium, sucrose and ammonium/nitrate
contents, initial medium pH, and inoculum size to determine their effects on biomass increase and the accumulation of total
phenols and flavonoids in adventitious roots ofEchinacea angustifolia. These roots were cultured under darkness in shake flasks for 4 weeks. IBA proved the best auxin for inducing root proliferation.
Root growth was inhibited when the initial pH was maintained below 5.0 or above 6.0. Nitrate, rather than ammonium, was more
necessary for root growth and phenolics accumulations. Overall, biomass increased and total phenol and flavonoid contents
were maximized under the following conditions: half-strength MS medium supplemented with 2 mg L-1 IBA, 5% (w/v) sucrose, 5:25 (mM) ammonium/nitrate ratio, pH adjusted to 6.0 before autoclaving, and an inoculum size of 10
g L-1 FW. These results indicate that the type ofin vitro environment strongly affects growth and the accumulation of phenolics from adventitious root cultures ofE. angustifolia. Such optimization is beneficial to large-scale production of biomass and secondary metabolites in that species. 相似文献
197.
The effects of endogenous levels of ethylene and phenolic compounds on somatic embryogenesis, medium-browning, and peroxidase
activity were evaluated in thin section cultures ofDoritaenopsis. Cultures were maintained for 8 weeks with four different treatments: i) thick leaf segment culture, ii) thin leaf section
culture, iii) thin leaf section culture with ventilation, or iv) thin leaf section culture after expiants were first washed.
Expiants cultured in closed vessels produced a larger number of somatic embryos than those reared in the ventilated vessels.
This enhanced formation confirmed the greater involvement of accumulated ethylene under non-ventilated conditions, because
wound-induced tissues from thin leaf sections normally release high level of ethylene. When expiants were washed in the liquid
medium and inoculated on the same solid medium, somatic embryo production was 1.7 and 18.5 times higher than in the thin section
cultures and thick segment cultures, respectively. Reducing the level of phenolics in expiants at the initial stage of culturing
apparently stimulated this embryo regeneration. 相似文献
198.
Jeong Wook Heo Kee Yoeup Paek Chang Ho Kang Chang Hoo Chun 《Journal of Plant Biology》2006,49(2):167-173
Air current patterns were visualized inside a scaled-up culture vessel under natural or forced ventilation. Metaldehyde particles
were used as tracers, and their patterns were recorded as video images by a high-resolution-and-contrast camera. Under natural
conditions, the air currents were mainly influenced by natural convection that developed due to the lighting scheme, which
caused differences in temperature among various articles in the chamber, including a sweet potato plantlet, supporting material,
a multi-cell tray, and the culture vessel. Under forced ventilation, the air current pattern and air speed were affected by
ventilation rates and by air-supply methods that were either parallel downward or circular upward. Uniformity of air movement
could be achieved with air distribution pipes inside a modified vessel. Under forced ventilation, growth, photosynthetic rate,
and transpiration of the micropropagated plantlets were enhanced around the air outlet as well as the inlet in the large-scale
vessel. Those plant responses were probably induced by uniform spatial distribution of air current and gas concentrations. 相似文献
199.
Kim YH Jeong DW Paek IB Ji HY Kim YC Sohn DH Lee HS 《Journal of chromatography. B, Analytical technologies in the biomedical and life sciences》2006,844(2):261-267
A rapid, sensitive and selective liquid chromatography-tandem mass spectrometric (LC-MS/MS) method for the determination of baicalein, baicalin, oroxylin A and wogonin, Scutellaria baicalensis active components in rat plasma was developed. After liquid-liquid extraction with 2-(3,4-dimethoxy-phenyl)-5,7-dihydroxy-chromen-4-one as internal standard, baicalein, baicalin, oroxylin A and wogonin were eluted from an Atlantis C(18) column within 7 min with isocratic mobile phase consisting of methanol and 0.1% formic acid (60:40, v/v). The analytes were detected using an electrospray ionization tandem mass spectrometry in the multiple reaction monitoring (MRM) mode. The standard curves were linear (r=1.000) over the concentration ranges of 5-500 ng/ml for baicalein, wogonin and oroxylin A and 5-5000 ng/ml for baicalin. The coefficients of variation and relative errors of baicalein, wogonin, oroxylin A and baicalin for intra- and inter-assay at three or four quality control (QC) levels were 0.8-6.1% and -4.0 to 5.8%, respectively. The lower limits of quantification for baicalein, wogonin, oroxylin A and baicalin were 5ng/ml using 50 microl of plasma sample. This method was successfully applied to the pharmacokinetic study of baicalein, baicalin, wogonin and oroxylin A after an intravenous administration of Scutellariae radix extract to male Sprague-Dawley rats. 相似文献
200.
G. Sivakumar K.W. Yu J.S. Lee J.K. Kang H.L. Lee W.J. Kim K.Y. Paek 《Engineering in Life Science》2006,6(4):372-383
Panax ginseng has strong anticancer, antidiabetic, antioxidant activity, various physiological functions, and is used as a nutritional and medicinal supplement. Tissue cultured mountain ginseng adventitious roots? (TCMGARs) powder, which is derived from commercial scale bioreactor cultures, was tested for its consumption safety. The reverse mutation, chromosomal aberration and the micronucleus tests were found to show no significant mutagenicity. Furthermore, thirteen weeks of repeated dose toxicity of TCMGARs oral doses from 300–900 mg/kg, with a four‐week recovery period, did not produce mortality or significant changes in the general behavior and gross appearance of the internal organs of rats. The absolute body weight, urine test, haematology, blood chemistry, absolute organ weight and histopathological examination of both main and recovery groups revealed that there were no differences between the control and the treated rats. These results confirm that TCMGARs are safe and nontoxic at an average dietary consumption level. 相似文献