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Lizhe An

Publications and source records attributed to Lizhe An.

18 recordsLinked to original sources
PubMed2007

NADPH oxidase-dependent hydrogen peroxide production, induced by salinity stress, may be involved in the regulation of total calcium in roots of wheat.

Hydrogen peroxide (H(2)O(2)) is often generated by cells and tissues under environmental stress. In this work, we provide evidence that plasma membrane (PM) NADPH oxidase-dependent H(2)O(2) production might act as an intermediate step in the NaCl-induced elevation of calcium (Ca) in roots of wheat. Remarkable increases in the content of total Ca were observed not only in roots exposed to NaCl but also in roots of seedlings exposed to exogenous H(2)O(2). In roots, H(2)O(2) production increased upon exposure to salt stress. PM vesicles were isolated from roots, and NADPH oxidase activity was determined by measuring superoxide anion (O(2)(-)) production. NADPH oxidase-dependent O(2)(-) production was 11.6nmolmg(-1)proteinmin(-1) in control vesicles, but 19.6nmol after NaCl treatment (24h), indicating that salt stress resulted in the activation of the PM NADPH oxidase. Furthermore, the NaCl-induced increase in total Ca was partially abolished by the addition of 150U/mL catalase (CAT), a H(2)O(2) scavenger, and also by 10microM diphenylane iodonium (DPI), a NADPH oxidase inhibitor. This data suggest that NADPH oxidase-dependent H(2)O(2) production might be involved in the modulation of the Ca content in wheat roots. In conclusion, our results show that salinity stress increases the total Ca content of wheat roots, which is partly due to PM NADPH oxidase-dependent H(2)O(2) generation.

Calcium↗
PubMed2007

Comparison of two gel filtration chromatographic methods for the purification of Lily symptomless virus.

Lily symptomless virus (LSV) occurs frequently in many Lilium species worldwide and often causes developmental abnormalities such as a smaller flower and lower bulb yield. In this study, two moderate and efficient gel filtration chromatography (GFC) methods was compared, these two techniques were, respectively, based on Superdex-200 HR and Sephacryl S-1000 SF. The products purified by the two methods were then characterized by measurements with UV-spectrophotometer, reverse transcriptase (RT)-PCR, transmission electron microscope (TEM), polyacrylamide gel electrophoresis (PAGE), Western blotting and matrix assisted laser desorption-ionisation/time-of-flight mass spectrometry (MALDI-TOF-MS). The final yield of purified LSV by the Superdex-200 HR GFC was 9.4 mg from 50 g of fresh infected tissues of Lanzhou lily. However, from the same amount tissues, only 5.6 mg of LSV were obtained by using Sephacryl S-1000 SF GFC. The Superdex-200 HR method was thus shown to be more suitable for the purification of LSV than the Sephacryl S-1000 SF GFC. The Superdex-200 HR method does not require costly equipment for density centrifugation and ultracentrifugation. Furthermore, it can provide an economical and efficient way to obtain purified products for the preparation of antibodies for serological diagnosis or LSV infection and related investigations.

Chromatography, Gel↗
PubMed2006

Properties of plasma membrane H+ -ATPase in salt-treated Populus euphratica callus.

The plasma membrane (PM) vesicles from Populus euphratica (P. euphratica) callus were isolated to investigate the properties of the PM H(+)-ATPase. An enrichment of sealed and oriented right-side-out PM vesicles was demonstrated by measurement of the purity and orientation of membrane vesicles in the upper phase fraction. Analysis of pH optimum, temperature effects and kinetic properties showed that the properties of the PM H(+)-ATPase from woody plant P. euphratica callus were consistent with those from herbaceous species. Application of various thiol reagents to the reaction revealed that reduced thiol groups were essential to maintain the PM H(+)-ATPase activity. In addition, there was increased H(+)-ATPase activity in the PM vesicles when callus was exposed to NaCl. Western blotting analysis demonstrated an enhancement of H(+)-ATPase content in NaCl-treated P. euphratica callus compared with the control.

Cell Membrane↗
PubMed2006

Phylogenetic diversity of culturable bacteria from alpine permafrost in the Tianshan Mountains, northwestern China.

Microbes have been discovered in permafrost sediments for nearly a century. However, microbiological analyses of alpine permafrost are very scarce. This study is a first attempt to describe the phylogenetic diversity of a culturable bacterial community isolated from alpine permafrost in the Tianshan Mountains in northwestern China. Aerobic 2.5-6.0x10(5) CFU/gdw (CFU per 1 gram of dry weight) on modified PYGV medium were recovered from alpine permafrost samples at 4 degrees C; among these, 91 bacterial isolates with different morphotypes were characterized by phenotypic properties, such as morphology, colony pigmentation, Gram staining, endospore formation and temperature range of growth. The isolates were further categorized based on amplified rDNA restriction analysis (ARDRA), and 51 representative isolates possessing distinct ARDRA patterns selected for subsequent 16S rDNA sequencing and phylogenetic analysis. The phylogenetic trees placed the 51 isolates in four major groups: the high-G+C Gram-positives, the low-G+C Gram-positives, Proteobacteria and the Cytophaga-Flavobacterium-Bacteroides (CFB) phylum. The most abundant and diverse isolates were members of Gram-positive bacteria, particularly the Arthrobacter as a dominant group in alpine permafrost culturable populations. Results of the Jukes-Cantor evolutionary distance matrix suggested that the vast majority of the isolates were different strains of known species, and three may represent new species within the genus Chryseobacterium of the CFB phylum. From this study, it is proposed that alpine permafrost sediments in the Tianshan Mountains provide a specific ecological niche for prolonging survival of diverse microbial lineages.

Arthrobacter↗
PubMed2006

Molecular cloning and characterization of a novel MAP kinase gene in Chorispora bungeana.

Chorispora bungeana Fisch. and C.A. Mey (Chorispora bungeana) is a rare alpine subnival plant species that is highly capable of resisting freezing environment. Since it is a stress-tolerant plant, we investigated the participation of mitogen-activated protein kinases (MAPKs) as possible mediators of abiotic stresses. We have isolated from Chorispora bungeana a new MAPK cDNA CbMAPK3 which encodes a 369 amino-acid protein with moderate to high nucleotide sequence similarity to previously reported plant MAPK genes. CbMAPK3 contains all 11 of the MAPK conserved subdomains and the phosphorylation motif TEY. The transcripts of CbMAPK3 were detected and no tissue-specific expression were observed in both roots and leaves, The transcripts of CbMAPK3 accumulated highly and rapidly when Chorispora bungeana treated with cold (4 and -4 degrees C), ABA and salinity stress. These results indicate that the CbMAPK3 may play an important role in response to environmental stresses.

Abscisic Acid↗
PubMed2006

Comparison of the virulence plasmid genomes of two strains of Shigella which lost the ability to bind Congo red.

We determined and analyzed the Shigella flexneri serotype 5 (pSF5) and S. dysenteriae serotype 1 (pSD1) virulence plasmid genomes. The total length of pSF5 is 136513 bp, including 165 open reading frames (ORFs). Of these ORFs, 133 were identified and 32 of those had no significant homology to proteins with known functions. The length of pSD1 is 182545 bp, including 224 ORFs, of which we identified 181. The remaining 43 ORFs were not significantly homologous to proteins with known functions. The insertion sequence (IS) elements are 53787 bp in pSF5, and 49616 bp in pSD1, which represents 39.4% and 27.1% of the genome, respectively. There are 22 IS element types in pSF5 and pSD1, among which we report ISEc8 and ISSbo6 for the first time in the Shigella virulence plasmid. Compared to pCP301, there are a large number of deleted genes and gene inversions in both pSF5 and pSD1. The ipa-mxi-spa locus in pSF5 is completely absent, and the genes related to the O-antigen biosynthesis are partially missing. In contrast, the above genes in pSD1 are integral, with the exception of virF. The whole genome analysis of the two plasmids shows that the loss of genes related to gene invasion or regulation also obliterates the ability of pPF5 and pSD1 to bind Congo red (Crb). Whether these genes determine the Crb function requires continued investigation.

Acyltransferases↗
PubMed2006

Role of poly-galacturonase inhibiting protein in plant defense.

Polygalacturonase-inhibiting proteins (PGIPs) are plant proteins believed to play an important role in the defense against plant pathogen fungals. PGIPs are glycoproteins located in plant cell wall which reduce the hydrolytic activity of polygalacturonases (PGs), limit the growth of plant pathogens, and also elicit defense responses in plant. Furthermore, PGIPs belong to the super family of leucine reach repeat (LRR) proteins which also include the products of several plant resistance genes. Many of the studies show the PGIP properties, molecular characteristics, and PGIP gene expression induced by some elicitors. Some of the studies review individual PGIP gene expression in different signal transduction pathways. This article summarizes the properties, different signal transduction mechanisms, detecting methods, transgenic plants, and function of PGIP. It also presents PGIP gene expression in different stages of maturity, tissues, and varieties. The review especially reports the particular PGIP gene expression induced by different biotic and abiotic stresses, offers some questions, and prospects the future study, which are needed in order to develop efficient strategies for disease-resistant plants. They may be useful for genetic engineering to obtain transgenic plants with increased tolerance to fungal infection, which decrease the use of insecticide.

Plant Physiological Phenomena↗
PubMed2006

Effect of lanthanum ions (La3+) on ferritin-regulated antioxidant process under PEG stress.

The physiological effects of lanthanum(III) ions on the ferritin-regulated antioxidant process were studied in wheat (Triticum aestivum L.) seedlings under polyethylene glycol (PEG) stress. Treatment with 0.1 mM La3+ resulted in increased levels of chlorophyll, carotenoid, proline, ascorbate, and reduced glutathione. The activities of superoxide dismutase, catalase, ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, glutathione reductase, and peroxidase were also increased after La3+ treatment. Treatment with La3+ seems to enhance the capacity of the reactive oxygen species scavenging system, affect the Fe2+ and Fe3+ electron-transfer process in ferritin, and restrain the formation of hydroxyl radical (OH.), alleviating the oxidative damage induced by PEG stress.

Antioxidants↗
PubMed2006

[Seasonal changes in foliar micro-and ultra structure of two Sabina species and their relationships with cold tolerance].

In this paper, the foliar micro-and ultra structure of Sabina przewalskii and S. chinensis during growth and dormancy seasons was observed under microscope and transmission electron microscope, and the foliar soluble sugar content was measured, aimed to probe into their relationships with cold tolerance. The results showed that the foliar surface cells of these two Sabina species were covered with thick cuticular membrane, and the well-developed arenchyma appeared in the mesophyll. In growth season, starch grains accumulated in chloroplasts, but in dormancy season, the accumulated starch grains disappeared or diminished, while soluble sugar content had a larger increase. In wintertime, the chloroplasts of S. chinensis were injured, with some abnormal chloroplasts, increased plastoglobuli and some lipid drops, while those of S. przewalskii were not obviously injured. It was suggested that the cold tolerance of the two Sabina species was related to their well-developed arenchyma, accumulation of starch grains in growth season, and increase of soluble sugar content in dormancy season. S. przewalskii had more marked increase of soluble sugar content, and its chloroplasts were more stable than S. chinensis.

Adaptation, Physiological↗
PubMed2005

Effects of nitric oxide on growth of maize seedling leaves in the presence or absence of ultraviolet-B radiation.

The leaves of maize seedlings were used to measure leaf biomass including leaf length, width and weight, and to examine the relationship between nitric oxide (NO) synthase activity in microsomes and cytosol to the exo- and endo-beta-glucanase activity during growth. It was found that ultraviolet-B radiation (UV-B radiation) strongly induced nitric oxide synthase (NOS) activity but caused both a decrease of leaf biomass and exo- or endo-beta-glucanase activity. In contrast, the NOS inhibitor and NO donor largely decreased the activity of NOS in non-irradiated seedlings. The inhibitor also reduced exo- and endo-beta-glucanase activity and leaf biomass while the donor increased the enzyme activity and leaf biomass under normal conditions. Alternatively, under ultraviolet-B, the additional inhibitor of NOS and NO donor appeared to compromise the effects of ultraviolet-B on glucanase activity and leaf biomass, making the relationship between NOS activity and glucanase activity negatively correlated. This suggests that the changes of NOS activity showed a positive correlation to glucanase activity and leaf biomass in the absence of ultraviolet-B, but a negative correlation to ultraviolet-B irradiation and NO donor treatment alone. It is assumed that exo- and endogenous NO is responsible for the up-regulation of regular growth and development without ultraviolet-B. Under UV-B radiation, however, it might function as a signaling molecule of ultraviolet-B inhibiting leaf growth of maize seedlings to carry out stress-signaling transduction.

Nitric Oxide↗
PubMed2005

Effects of enhanced ultraviolet-B radiation on algae and cyanobacteria.

This article provides an overview of existing literature on the ultraviolet-B (UV-B) radiation effects on algae and cyanobacteria. We report on the effects of UV-B radiation to the growth and development, biomass, sensitivity, photosynthetic pigments, UV-B absorbing compounds, photosynthesis, protein and DNA damage, enzyme activity, nitrogen fixation and assimilation of nitrogen, protective mechanisms of algae and cyanobacteria, the accommodation of algae and cyanobacteria to environmental stress, and the effects to ecology system. Many of the studies show the dramatic effects of UV-B radiation; but typically these studies were conducted under conditions with supplemental UV-B irradiance that was higher than would ever occur outside experimental conditions or natural condition. A few of the studies reviewed used experimental conditions and supplemental UV-B irradiance that approached realism. Enhanced UV-B generally decreased chlorophyll content, whereas it increased UV-B absorbing compounds in many algae. Decrease in photosynthesis, particularly at higher UV-B doses, was due to both direct (effect on photosystem) and indirect (decrease in pigments) effects. The decreases in chlorophyll pigments and photosynthesis resulted in lower biomass. However, algae and cyanobacteria have evolved various avoidance and repair mechanisms to protect themselves against the damaging effects of UV radiation to acclimate to enhanced UV-B radiation. The review points to areas where further studies on the relationships among nitrogenase, Rubisco, antioxidase activity, signal, antioxidants, and free radicals under enhanced UV-B are needed to quantify the effects of UV-B radiation on algae and cyanobacteria. These studies are needed in order to develop dose response functions that can facilitate development of dynamic simulation models for use in UV-B and other environmental impact assessments.

Cyanobacteria↗
PubMed2005

16S rRNA sequences and differences in bacteria isolated from the Muztag Ata glacier at increasing depths.

Small subunit 16S rRNA sequences, growth temperatures, and phylogenetic relationships have been established for 129 bacterial isolates recovered under aerobic growth conditions from different regions of a 22-m ice core from the Muztag Ata Mountain glacier on the Pamirs Plateau (China). Only 11% were psychrophiles (grew at 2 degrees C or -2 degrees C up to approximately 20 degrees C), although the majority (82%) were psychrotolerant (grew at 2 degrees C or -2 degrees C up to 37 degrees C). The majority of the isolates had 16S rRNA sequences similar to previously determined sequences, ranging from 85% to 100% identical to database sequences. Based on their 16S rRNA sequences, 42.6% of the isolates were high-G+C (HGC) gram-positive bacteria, 23.3% were gamma-Proteobacteria, 14.7% were alpha-Proteobacteria, 14.7% were Flavobacteria, and 4.7% were low-G+C (LGC) gram-positive bacteria. There were clear differences in the depth distribution, with Proteobacteria, HGC/Cytophaga-Flavobacterium-Bacteroides (CFB), Proteobacteria, LGC/CFB/HGC, Cryobacterium psychrophilum, HGC/CFB, Proteobacteria/HGC/CFB, and HGC/CFB being the predominant isolates from ice that originated from 2.7 to 3.8, 6.2, 7.5, 8.3, 9.0, 9.7, 12.5, and 15.3 m below the surface, respectively. This layered distribution of bacterial isolates presumably reflects both differences in bacteria inhabiting the glacier's surface, differences in bacteria deposited serendipitously on the glacier's surface by wind and snowfall, and nutrient availability within the ice.

Aerobiosis↗
PubMed2004

[Effect of the combination of cadmium and UV-B radiation on soybean growth].

This paper studied the characteristics of soybean growth under the stress of Cd, UV-B radiation and their combination. The results showed that UV-B radiation gave a more pronounced inhibition on soybean growth than cadmium. Under UV-B radiation, the internode differentiation and elongation were inhibited, the internode and plant height were reduced, and the activities of SOD and POD had an apparent increase. Cd2+ could antagonize the effect of UV-B radiation on POD activity, and inhibit indole-3-acetic acid (IAA) oxidase activity. A significant decrease of POD and IAA oxidase activities in soybean was detected when exposed to combined UV-B and Cd2+, compared with UV-B radiation only. The decrease of POD and IAA oxidase activities was related to the increase of IAA contents and photosynthetic activity, which might account for the increases of biomass and plant height. Moreover, the combined stress enhanced the inhibition of root growth, and significantly decreased root length. The IAA oxidase and POD activities and photosynthesis rate might be the crucial factors determining the pattern of soybean growth under the stress of Cd2+ in combination with UV-B radiation.

Cadmium↗
PubMed2004

[A new impulse noise filter based on pulse coupled neural network].

This paper presents a new impulse noise filter based on pulse coupled neural networks according to the apparent difference of gray value between noised pixels and the pixels around them. Comparing with the state-of-the-art denoised PCNN filter, the step by step modifying algorithm based on PCNN also, the new PCNN filter suggested in this paper costs less computation and less execution time. At the same time this new PCNN filter has been compared with other nonlinear filters, such as median filter, the stack filter based on omnidirectional structural elements constrains, the Omnidirectional morphology Open-Closing maximum filter (OOCmax) and the Omnidirectional morphology Close-Opening minimum (OCOmin) filter. The results of simulation shows that this algorithm is superior to standard median filter, the state-of-the-art PCNN filter, the maximal, minimal morphological filter with omnidirectional structuring elements, and the optimal stack filter based on omnidirectional structural elements constrains in the aspect of the impulse noise removal. What is more important is that this algorithm can keep the details of images more effectively.

Computer Simulation↗
PubMed2003

The cascade mechanisms of nitric oxide as a second messenger of ultraviolet B in inhibiting mesocotyl elongations.

In this report, a number of physiological aspects was examined during developmental growth of maize seedling's mesocotyl. It was found that ultraviolet B (UVB) radiation was able to significantly induce nitric oxide synthase (NOS) activities and speedup the release of apparent nitric oxide (NO) of mesocotyl and that exogenous NO donor's rhizospheric treatments may mimic the responses of the mesocotyl to UVB radiation, such as the inhibition of mesocotyl elongation, the decrease in exo- and endoglucanase activities and the increase in protein content of cell wall of mesocotyl. When the seedlings were treated with N-nitro-L-arginine, an inhibitor of NOS, the mesocotyl elongation was promoted, the exo- and endoglucanase activities were raised and the protein content was reduced. However, under UVB radiation, the effects of exogenous NO on several physiological aspects of mesocotyl were similar to those of exogenous reactive oxygen species (ROS) eliminator, N-acetyl-cysteine. All the physiological changes were associated with either the exogenous NO supply or the activities of NOS in plant. Accordingly, it is assumed that reduction in mesocotyl length caused by UVB radiation was possibly achieved through modification of the chemical properties of the cell wall polysaccharides, which was induced by NO and ROS synergically mediated changes in exo- and endo-beta-D-glucanases activities in cell walls, and NO was one of the main signaling molecule of UVB radiation in inhibiting mesocotyl elongations. So NO might function as both a second messenger and an antioxidant of UVB radiation during developmental growth of the mesocotyl.

Nitric Oxide↗
PubMed2002

[Present status and prospects in research on effect of enhanced UV-B radiation on plants].

Current research status on the effect of enhanced UV-B radiation on plants was reviewed in this paper. The main research fields involved plant growth and morphological structure, plant physiological and biochemical metabolism, plant genetic material, UV-B-absorbing compounds and some gene expression, population, and ecosystem. In addition, some issues worthy to be studied in this field in future were proposed.

Ecosystem↗
PubMed2002

[Cumulative effect of solar ultraviolet-B radiation on pollen germination and tube growth of 19 species in vitro].

In order to determine the response of pollen to UV-B irradiation and the cumulative effects of UV-B exposure time on pollen germination and tube growth of plants, 19 species were investigated in vitro by exposing their pollen grains to two levels of enhanced ultravioet-B(UV-BBE) (280-320 nm, 350 and 500 mW/m2 biologically effective UV-B radiation), simulating 8% and 21% stratospheric ozone depletion in Lanzhou, China (36.04 degrees N, 1550 m), and to no UV-B (control group). Compared with the control, enhanced UV-B radiation significantly inhibited pollen germination and tube growth in most species. Higher UV-B flux rate caused greater inhibitory effect than lower UV-B radiation level. Several test plants exhibited insensitivity, even stimulation of pollen germination and tube growth to UV-B. The reduction in pollen germination rate and tube growth increased with exposure time, which indicated a cumulative effect of UV-B radiation. It is concluded that changes in pollen susceptibility to UV-B would have a serious ecological consequence under natural conditions.

Flowers↗