Biomedical subjects

Xiaoqiang Liu

Publications and source records attributed to Xiaoqiang Liu.

3 recordsLinked to original sources

PubMed2006

OsWRKY71, a rice transcription factor, is involved in rice defense response.

WRKY proteins are a large family of transcription factors that mainly participate in plant biotic stress responses. So far, one hundred and five OsWRKY genes have been predicted in the rice genome. To identify OsWRKY genes that might function in inducible defense responses, a phylogenetic tree including 184 WRKY proteins from Arabidopsis thaliana, rice, and other species was constructed. Based on the phylogenetic analysis, ten candidate OsWRKY genes that may be involved in defense responses were isolated from salicylic acid (SA)-treated rice seedlings. One of them, OsWRKY71, was up-regulated by several defense signaling molecules, such as SA, methyl jasmonate (MeJA), 1-aminocyclo-propane-1-carboxylic acid (ACC), as well as wounding and pathogen infection, suggesting that OsWRKY71 might function in rice biotic stress response. Transient expression of OsWRKY71:GFP fusion protein in onion epidermis cells revealed that OsWRKY71 was localized in the nucleus. Overexpression of OsWRKY71 gene in rice resulted in enhanced resistance to virulent bacterial pathogens Xanthomonas oryzae pv. oryzae (Xoo) 13751. Furthermore, two marker genes in defense signaling pathway, OsNPR1 and OsPR1b, were constitutively expressed in OsWRKY71-overexpressing transgenic plants. These results suggest that OsWRKY71 might function as a transcriptional regulator upstream of OsNPR1 and OsPR1b in rice defense signaling pathways.

Arabidopsis↗

PubMed2005

EUI1, encoding a putative cytochrome P450 monooxygenase, regulates internode elongation by modulating gibberellin responses in rice.

Elongation of rice internodes is one of the most important agronomic traits, which determines the plant height and underlies the grain yield. It has been shown that the elongation of internodes is under genetic control, and various factors are implicated in the process. Here, we report a detailed characterization of an elongated uppermost internode1 (eui1) mutant, which has been used in hybrid rice breeding. In the eui1-2 mutant, the cell lengths in the uppermost internodes are significantly longer than that of wild type and thus give rise to the elongated uppermost internode. It was found that the level of active gibberellin was elevated in the mutant, whereas its growth in response to gibberellin is similar to that of the wild type, suggesting that the higher level accumulation of gibberellin in the eui1 mutant causes the abnormal elongation of the uppermost internode. Consistently, the expression levels of several genes which encode gibberellin biosynthesis enzymes were altered. We cloned the EUI1 gene, which encodes a putative cytochrome P450 monooxygenase, by map-based cloning and found that EUI1 was weakly expressed in most tissues, but preferentially in young panicles. To confirm its function, transgenic experiments with different constructs of EUI1 were conducted. Overexpression of EUI1 gave rise to the gibberellin-deficient-like phenotypes, which could be partially reversed by supplementation with gibberellin. Furthermore, apart from the alteration of expression levels of the gibberellin biosynthesis genes, accumulation of SLR1 protein was found in the overexpressing transgenic plants, indicating that the expression level of EUI1 is implicated in both gibberellin-mediated SLR1 destruction and a feedback regulation in gibberellin biosynthesis. Therefore, we proposed that EUI1 plays a negative role in gibberellin-mediated regulation of cell elongation in the uppermost internode of rice.

Amino Acid Sequence↗

PubMed2004

In situ circular dichroic electrochemical study of bilirubin and bovine serum albumin complex.

The electrooxidation of bilirubin (BR) and bovine serum albumin (BSA) complexes was studied by in situ circular dichroism (CD) spectroelectrochemistry. The result showed that the mechanism of the whole electrooxidation process of this complex corresponded to electrochemical processes (EE mechanism) in aqueous solution. Some parameters of the process were obtained by double logarithm method, differential method and nonlinear regression method. In visible region, CD spectra of the two enantiomeric components of the complex and their fraction distribution against applied potentials were obtained by singular value decomposition least-square (SVDLS) method. Meanwhile, the distribution of the five components of secondary structure was also obtained by the same method in far-UV region. The peak potential gotten from EE mechanism corresponds to a turning point for the component transition, beyond which the whole reaction reaches a new equilibrium. Under applied positive potentials, the enantiomeric equilibrium between M and P form is broken and M form transfers to its enantiomer of P, while the fraction of alpha-helix increases and that improves the transition to P form.

Animals↗