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Previous study on refolding of sulfur oxygenase reductase (SOR) inclusion bodies from recombinant Escherichia coil showed that iron was critical to the activity of the SOR from Acidianus ambivaiens. In this study, enzymatic assays showed that 2,2'-Dipyridyl, Tiron and 8-hydroxyquinoline, which are specific for chelating ferrous or ferric ions, strongly inhibited the activity of SOR from A. tengchongensis, suggesting that iron atom is essential for SOR activity. Alignment of several functionally identified SORs and SOR-like sequences from genome database revealed a conserved, putative iron binding motif, H86-X3-H90-Xn-E114-Xn-E129 (numbering according to the Acidianus tengchongensis SOR sequence). Three mutants of SOR were generated by site-directed mutagenesis of H86, H90 and E129 into phenylalanine or alanine residue in this study. Circular dichroism spectrum determination indicated that there was no change of the secondary structures of mutant SORs, H86F, H90F and E129A, but all mutants were completely inactive. Through determination of iron contents we found that SOR mutants of H86F, H90F and E129A completely or partially lost iron, while mutants of C31S, C101S, and C104S (generated in a previous study) did not. This result indicated that H86, H90 and E129 but not C31, C101, and C104 were involved in binding to iron atom. Based on this and previous studies, it is proposed that the concerved motifs, C31-Xn-C101-X2-C104 and H86-X3-H90-X23-E114-X14-(E/D)129, are respectively for sulfur and molecular oxygen binding and activation. These two conserved motifs are essential elements for the SOR activity. [ABSTRACT FROM AUTHOR]

The phenomenon of panicle enclosure in rice is mainly caused by the shortening of uppermost internode. Elucidating the molecular mechanism of panicle enclosure will be helpful for solving the problem of panicle enclosure in male sterile lines and creating new germplasms in rice. We acquired a monogenic recessive enclosed panicle mutant, named as esp2 ( enclosed shorter panicle 2), from the tissue culture progeny of indica rice cultivar Minghui-86. In the mutant, panicles were entirely enclosed by flag leaf sheaths and the uppermost internode was almost completely degenerated, but the other internodes did not have obvious changes in length. Genetic analysis indicated that the mutant phenotype was controlled by a recessive gene, which could be steadily inherited and was not affected by genetic background. Apparently, ESP2 is a key gene for the development of uppermost internode in rice. Using an F population of a cross between esp2 and a japonica rice cultivar Xiushui-13 as well as SSR and InDel markers, we fine mapped ESP2 to a 14-kb region on the end of the short arm of chromosome 1. According to the rice genome sequence annotation, only one intact gene exists in this region, namely, a putative phosphatidylserine synthase gene. Sequencing analysis on the mutant and the wild type indicated that this gene was inserted by a 5287-bp retrotransposon sequence. Hence, we took this gene as a candidate of ESP2. The results of this study will facilitate the cloning and functional analysis of ESP2 gene. [ABSTRACT FROM AUTHOR]

Presents the genetic analysis and gene mapping of leafy head, a mutant blocking the differentiation of rachis branches in rice. Characteristics of the mutant; Influence of the genetic background on the mutant phenotype; Positional cloning and functional study of the mutant gene.

Describes the high spinning speed [sup 1]H magic angle spinning nuclear magnetic resonance technique for formamide intercalation compound. Effects of the formation of hydrogen bond; Understanding the interaction between natural organic matters and clay minerals; Estimation of the intercalation degree through X-ray diffraction patterns.

Deals with a study which explored the changes of hydroxyl species on diatomite surface under different thermal treatment conditions using high spinning speed H magic-angle spinning nuclear magnetic resonance. Materials and methods; Results; Discussion.

Features a study which constructed both FRT-FRT and LoxP-LoxP sites that are the target sequences of site-specific recombinases in a vector, C4LFY, using the recombinant DNA technique. Background of the study; Materials and method; Results and discussion.