Showing papers by "Hua Zhang published in 2007"

A Mutation in MRH2 Kinesin Enhances the Root Hair Tip Growth Defect Caused by Constitutively Activated ROP2 Small GTPase in Arabidopsis

Abstract: Root hair tip growth provides a unique model system for the study of plant cell polarity. Transgenic plants expressing constitutively active (CA) forms of ROP (Rho-of-plants) GTPases have been shown to cause the disruption of root hair polarity likely as a result of the alteration of actin filaments (AF) and microtubules (MT) organization. Towards understanding the mechanism by which ROP controls the cytoskeletal organization during root hair tip growth, we have screened for CA-rop2 suppressors or enhancers using CA1-1, a transgenic line that expresses CA-rop2 and shows only mild disruption of tip growth. Here, we report the characterization of a CA-rop2 enhancer (cae1-1 CA1-1) that exhibits bulbous root hairs. The cae1-1 mutation on its own caused a waving and branching root hair phenotype. CAE1 encodes the root hair growth-related, ARM domain-containing kinesin-like protein MRH2 (and thus cae1-1 was renamed to mrh2-3). Cortical MT displayed fragmentation and random orientation in mrh2 root hairs. Consistently, the MT-stabilizing drug taxol could partially rescue the wavy root hair phenotype of mrh2-3, and the MT-depolymerizing drug Oryzalin slightly enhanced the root hair tip growth defect in CA1-1. Interestingly, the addition of the actin-depolymerizing drug Latrunculin B further enhanced the Oryzalin effect. This indicates that the cross-talk of MT and AF organization is important for the mrh2-3 CA1-1 phenotype. Although we did not observe an apparent effect of the MRH2 mutation in AF organization, we found that mrh2-3 root hair growth was more sensitive to Latrunculin B. Moreover, an ARM domain-containing MRH2 fragment could bind to the polymerized actin in vitro. Therefore, our genetic analyses, together with cell biological and pharmacological evidence, suggest that the plant-specific kinesin-related protein MRH2 is an important component that controls MT organization and is likely involved in the ROP2 GTPase-controlled coordination of AF and MT during polarized growth of root hairs.

Indole alkaloids from three species of the Ervatamia genus: E. officinalis, E. divaricata, and E. divaricata Gouyahua.

Abstract: Six new indole alkaloids, 14,15-didehydro-10,11-dimethoxy-16-epivincamine (1), 14,15-didehydro-10-hydroxy-11-methoxy-16-epivincamine (2), 14,15-didehydro-10,11-dimethoxyvincamine (3), 14,15-didehydro-10-hydroxy-11-methoxyvincamine (4), 19,20-didehydro-6α-hydroxyervatamine (5), and dehydroxyervataminol (6), along with 36 known indole alkaloids, were isolated from three species, E. officinalis, E. divaricata, and E. divaricata Gouyahua, of the Ervatamia genus. The structures of these alkaloids were characterized on the basis of spectroscopic methods and chemical correlation. The in vitro cytotoxic activities of all the alkaloids except 7, 18, 27, 38, 40, and 44 against the tumor cell lines P-388 murine leukemia and A-549 human lung carcinoma were evaluated. Only the dimeric indole alkaloids showed cytotoxic activities.

Development and evaluation of Mandarin disyllabic materials for speech audiometry in China

Abstract: The purpose of this study is to develop and evaluate disyllabic Mandarin speech test materials (MSTMs) in order to facilitate wider use of speech audiometry in Chinese audiology clinics. Phonologically balanced Mandarin disyllabic materials with high familiarity were designed based on the basic rules for developing speech materials and the particular characteristics of Mandarin, and recorded digitally. In order to establish the validity and reliability of these Mandarin disyllabic materials, equivalence of difficulty between the word lists was evaluated for a group of 60 subjects (age-range 18–25 years) with normal hearing. Subsequently, performance-intensity (PI) functions were measured in a group of 30 subjects with normal hearing (age-range 18–25 years), and a group of 35 subjects with sensineural hearing loss. The nine lists of Mandarin disyllabic materials were found to have sufficient reliability and validity to be used in clinical situations

A Comparative Study of Acrylamide Formation Induced by Microwave and Conventional Heating Methods

Abstract: In this study, the formation of acrylamide upon treatment with microwave and conventional heating, boiling, or frying was investigated in both Asn/Fru and Asn/Glc model systems and in potato chips. Acrylamide levels were analyzed by HPLC method, which was confirmed by HPLC-MS/MS. Present results in model systems showed that pH value had a complex influence on the formation of acrylamide in the 2 systems during both microwaving (600 W) and boiling (120 +/- 1 degrees C). At pH < 8.0, acrylamide content increased with increasing the pH value, reaching the maximum at pH 8.0 whereas acrylamide content decreased with the increase of pH. Regardless of pH and heating methods, acrylamide content generally increased with increasing treatment time. Surprisingly, all present results showed that microwave heating not only induced acrylamide formation in the 2 model systems but also facilitated more acrylamide to be formed as compared to the boiling method at identical pH and treatment time. At pH 4.0, 8.0, and 10.0, the larger the microwave power, the more the acrylamide content. Consistent with the above observation, treatment of potato chips with microwave heating for 2.5 to 3.5 min in the range 550 to 750 W similarly resulted in acrylamide formation. The highest acrylamide content was formed by 750 W microwave treatment as 0.897 +/- 0.099 mg/kg, which was significantly higher than that produced by traditional frying (180 +/- 1 degrees C), 0.645 +/- 0.035 mg/kg (P < 0.05).

Recyclable Hydrophilic−Hydrophobic Micropatterns on Glass for Microarray Applications

Abstract: A novel method for fabricating recyclable hydrophilic−hydrophobic micropatterns on glass chips is presented. TiOx patterns (100−2000 μm) were sputtered on glass chips via a through-hole mask. The patterned chips were then vapor-coated with fluoroalkylsilane, for example, (heptadecafluoro-1,1,2,2-tetrahydrodecyl)triethoxysilane (FTES) to form a hydrophobic coating layer. The fluoroalkyl chain of FTES film on TiOx patterns was photocleaved under UV irradiation, exposing the fresh hydrophilic TiOx patterns. The resulting chip could be used multiple times by repeating the coating and photocleaving processes with negligible deterioration of the hydrophobic FTES film coated on glass. If desired, bare glass patterns could also be generated by removing the TiOx patterns with KOH. The patterned glass chips have been successfully used for microarray fabrication.

Microstructure and mechanical properties of multilayer-lined composite pipes prepared by SHS centrifugal-thermite process

Abstract: Using a self-propagating high-temperature synthesis centrifugal-thermite process, pipes were lined with a multiphase ceramic layer. The ceramic layer was metallurgically joined with an intermediate intermetallic layer, situated between the base metal and the ceramic layer. The microstructures of the intermetallic layer, the multiphase ceramic layer, and the interfaces between them were investigated. The results showed that ceramic layer was composed of Al 2 O 3 , TiO 2 , and TiC while the intermediate layer contained AlFe, AlCrFe, and NiFe. Under the action of the centrifugal force, the phase TiC settled in the interface between the intermetallic and ceramic layers. The good wettability of TiC by ferrous metals and by Al 2 O 3 , the intermetallic layer and ceramic layer resulted in a good bond with improved bonding strength. Mechanical characterization of the pipes showed a significant improvement over conventional thermite self-propagating high-temperature synthesis (SHS) methods.

Pulsed-force-mode AFM studies of polyphenylene dendrimers on self-assembled monolayers

Abstract: Pulsed-force-mode atomic force microscopy (PFM-AFM) with a chemically modified tip was employed to measure the topography and adhesion force images of homoaggregates of fourth generation polyphenylene and carboxylic-acid-functionalized second generation polyphenylene dendrimers on hydrophilic self-assembled monolayers (SAMs). Although from the AFM topographic image the dendrimers could not be discriminated, from the adhesion image, the respective homoaggregates were easily discriminated. The determination is based on the different adhesive interactions between the dendrimers and the chemically modified tip, which are related to the chemical nature of the outer-surface functional groups, and the adsorbed water layer on hydrophilic surfaces under ambient conditions. It shows that PFM-AFM with chemically modified tips has nanoscale chemical spatial resolution.

Semiconductor nanocomposites of emissive flexible random copolymers and CdTe nanocrystals : preparation, characterization, and optoelectronic properties

Abstract: Synthesis and characterization of a series of new emissive flexible copolymers composed of two kinds of special side-chain functional groups is demonstrated. One of the side-chain groups provides emissive properties, while the other serves as the ligand unit. The copolymers are used to prepare a new kind of CdTe nanocrystal-based semiconductor nanocomposite. Their structures and morphologies are characterized and their optoelectronic properties are studied. The results reveal that an energy-transfer process from the emissive random copolymers to the CdTe nanocrystals occurs, while a photoinduced charge transfer is estimated to be thermodynamically forbidden.

Differential gene expression of aldolase C (ALDOC) and hypoxic adaptation in chickens

Abstract: Summary Two sequence variants of the aldolase C (ALDOC) gene were discovered based on comparison of the sequences from an altiplano chicken breed (Tibetan chicken) and two lowland breeds (White Leghorn and ShouGuang). Gel-shift results indicated that one of these variants, L25375:c.310-258G>A, was able to bind hypoxia-induced factor-l (HIF1A), therefore, functioning as a hypoxia response element (HRE). The combined activity of the HRE and HIF1A could increase under the influence of a hypoxic stimulus. Hypoxia leads to increased death rates of chicken embryos, while the L25375:c.310-258G>A described herein is prevalent in healthy embryos grown under hypoxic conditions. Fluorescence quantitative real-time PCR results revealed that HIF1A upregulated the transcript level of the glycolytic enzyme ALDOC in the brain and skeletal muscle of animals subjected to hypoxia. Thus, a large amount of ATP is produced by increased glycolysis, allowing the organism to meet energy metabolism demands. As such, we believe this sequence variant is an adaptation to external anoxic environment.

Ablation Resistance and Mechanical/ Conductive Properties of ZrB2 Reinforced Carbon Based Composites:

Abstract: Zirconium diboride reinforced carbon (ZrB2/C) particulate composites are prepared from petroleum coke, coal tar pitch, and ZrB2 powder by hot-pressing. The ablation, mechanical, thermal, and electrical properties of the composites are studied. Results show that the composites have excellent flexural strength and thermal conductivity, with highest values reaching 131 MPa and 161 W/mK for a 10% ZrB2 addition in raw materials. The electrical resistivity reduces rapidly with increasing amount of ZrB2. The values of mass and linear ablation rates are lower in the composites than those measured for pure carbon, decreasing with increasing ZrB2 content, confirming that these materials are promising for ultrahigh temperature materials. Correlations between properties and microstructure of the composites are also discussed.

Primary investigation of central auditory function in patients with temporal lobe epilepsy

Abstract: Objective To investigate the function of central auditory, Speech - perception - in - noise test （SPIN test） was used to assess that whether temporal lobe epilepsy patients have central auditory processing disorders. Methods Four audiological test were performed in 9 patients with temporal lobe epilepsy and 19 age- matched normal heating persons as controls, which include pure tone audiometry, acoustic immittanee measurement, ABR（ auditory brainstem response） and SPIN test. All the temporal lobe epilepsy patients were performed by CT or MRI and diagnosed by the neurologists prior to the test. The testing metiarals of speech and noise in SPIN test was recorded in independent tracks and the S/N was identified by - 25 dB by pre - experiment. In the test, every words were read twice and both the results were recorded. Results In the ABR test, only wave V latency showed longer values in the left ear, other waves likeⅠ , Ⅲ and inter - peak intervals hadnt shown significant statistical differences in both ears of temporal lobe epilepsy patients. However, In the SPIN test,there's no significant statistical differences in both left and right ears of the controls by the first- time heating（ P =0. 107 ） ,and the differences showed by the second- time hearing （P = 0. 048 ） ; but in the comparition of both ears in temporal lobe epilepsy patients, both time of heating showed no significant statistical differences with P = 0. 174 and P = 0. 163. In additional, the SPIN recognition score of the temporal lobe epilepsy patients ,whether in the fist or second time heating ,whether in the monaural or binaural modals, presented significant statistical differences compared to the controls （ P =0. 000）. Conclusions There was no statistically significant difference in pure tone audiometry and ABR test for all the groups. But the speech recognition score obtained from SPIN test of temprol lobe epilepsy patients is lower than the normal persons,which has statistically significant difference. （P <0. 001 ） Then we can come to the conclusion that Temporal lobe epilepsy patients had central auditory dysfunctions and SPIN test is a sensitive way to assess this abnormal. Key words: Epilepsy, temporal lobe; Auditory perception; Central nervous, system; Noise

The profile of alkali-soluble phenolic acids in maize stover, and rice and wheat straws

Abstract: Nine alkali-soluble phenolic acids (gallic acid, protocatechuic acid, p-hydroxybenzoic acid, vanillic acid, caffeic acid, syringic acid, trans-p-coumaric acid, trans-ferulic acid, sinapic acid) in maize stover, and rice and wheat straws were determined by HPLC after alkaline hydrolysis. The most abundant amount of total alkali-soluble phenolic acids was detected in maize stover, followed by rice straw and wheat straw, accounting for, %: 1.23, 1.21 and 0.87 on DM basis, respectively. Trans-p-coumaric acid and trans-ferulic acid were the preponderant phenolic acids in all three kinds of crop residues studied. Nine phenolic acids were found to be present in CAU 108 maize stover, but protocatechuic acid, p-hydroxybenzoic acid and caffeic acid were not detected in rice and wheat straws.

Normative data of disyllabic Mandarin speech test materials for normally hearing people

Abstract: OBJECTIVE To analyze the reliability of disyllabic Mandarin speech test materials (MSTM) which had previously been evaluated the equivalence of difficulty, and to establish the performance-intensity function (P-I function) for people with normal hearing. METHOD Thirty-five subjects (the age-range 18-25 years) with normal hearing who speak Mandarin well in their daily lives were enrolled in this study. Five of them participated the pilot study, which aimed to identify a presentation level for the formal test. The other thirty subjects participated in the formal speech perception test. The results were analyzed statistically using SPSS 11.0 software. Nine lists of the Mandarin disyllabic materials with equal difficulty were utilized. RESULT P-I function was y = -200.9 + 13.4x - 0.14x2. The sound pressure level of speech corresponding to a 50% recognition score was 26.4 dB SPL, or 6.4 dB HL. CONCLUSION This study has established the P-I function of the Mandarin disyllabic materials with equal difficulty, which provides the normative data for identifying the normal hearing in a clinical setting.