[Show abstract][Hide abstract] ABSTRACT: We report improved whole-genome shotgun sequences for the genomes of indica and japonica rice, both with multimegabase contiguity, or almost 1,000-fold improvement over the drafts of 2002. Tested against a nonredundant collection of 19,079 full-length cDNAs, 97.7% of the genes are aligned, without fragmentation, to the mapped super-scaffolds of one or the other genome. We introduce a gene identification procedure for plants that does not rely on similarity to known genes to remove erroneous predictions resulting from transposable elements. Using the available EST data to adjust for residual errors in the predictions, the estimated gene count is at least 38,000-40,000. Only 2%-3% of the genes are unique to any one subspecies, comparable to the amount of sequence that might still be missing. Despite this lack of variation in gene content, there is enormous variation in the intergenic regions. At least a quarter of the two sequences could not be aligned, and where they could be aligned, single nucleotide polymorphism (SNP) rates varied from as little as 3.0 SNP/kb in the coding regions to 27.6 SNP/kb in the transposable elements. A more inclusive new approach for analyzing duplication history is introduced here. It reveals an ancient whole-genome duplication, a recent segmental duplication on Chromosomes 11 and 12, and massive ongoing individual gene duplications. We find 18 distinct pairs of duplicated segments that cover 65.7% of the genome; 17 of these pairs date back to a common time before the divergence of the grasses. More important, ongoing individual gene duplications provide a never-ending source of raw material for gene genesis and are major contributors to the differences between members of the grass family.
[Show abstract][Hide abstract] ABSTRACT: An HPLC method was established for the determination of hesperidin and naringin in the Fructus Aurantii Immaturus and Fructus Aurantii from different places. Hesperidin and narigin were separated on a Hypersil ODS1 column with acetonitrile-0.5% acetic acid (volume ratio of 22:78) as the mobile phase and detected at 283 nm. The flow rate was 1.0 mL/min. The column temperature was set at 35 degrees C. The calibration curves were linear in the ranges of 0.060 g/L-0.604 g/L and 0.0125 g/L-0.125 g/L for naringin and hesperidin respectively. The average recoveries were 97.1% for naringin and 95.3% for hesperidin. The method is simple, rapid, accurate and reliable.
No preview · Article · Dec 2002 · Se pu = Chinese journal of chromatography / Zhongguo hua xue hui
[Show abstract][Hide abstract] ABSTRACT: We have produced a draft sequence of the rice genome for the most widely cultivated subspecies in China, Oryza sativa L. ssp.indica, by whole-genome shotgun sequencing. The genome was 466 megabases in size, with an estimated 46,022 to 55,615 genes. Functional
coverage in the assembled sequences was 92.0%. About 42.2% of the genome was in exact 20-nucleotide oligomer repeats, and
most of the transposons were in the intergenic regions between genes. Although 80.6% of predicted Arabidopsis thaliana genes had a homolog in rice, only 49.4% of predicted rice genes had a homolog in A. thaliana. The large proportion of rice genes with no recognizable homologs is due to a gradient in the GC content of rice coding sequences.
[Show abstract][Hide abstract] ABSTRACT: The sequence of the rice genome holds fundamental information for its biology, including physiology, genetics, development, and evolution, as well as information on many beneficial phenotypes of economic significance. Using a “whole genome shotgun” approach, we have produced a draft rice genome sequence ofOryza sativa ssp.indica, the major crop rice subspecies in China and many other regions of Asia. The draft genome sequence is constructed from over 4.3 million successful sequencing traces with an accumulative total length of 2214.9 Mb. The initial assembly of the non-redundant sequences reached 409.76 Mb in length, based on 3.30 million successful sequencing traces with a total length of 1797.4 Mb from anindica variant cultivar93-11, giving an estimated coverage of 95.29% of the rice genome with an average base accuracy of higher than 99%. The coverage of the draft sequence, the randomness of the sequence distribution, and the consistency of BIG-ASSEMBLER, a custom-designed software package used for the initial assembly, were verified rigorously by comparisons against finished BAC clone sequences from bothindica andjapanica strains, available from the public databases. Over all, 96.3% of full-length cDNAs, 96.4% of STS, STR, RFLP markers, 94.0% of ESTs and 94.9% unigene clusters were identified from the draft sequence. Our preliminary analysis on the data set shows that our rice draft sequence is consistent with the comman standard accepted by the genome sequencing community. The unconditional release of the draft to the public also undoubtedly provides a fundamental resource to the international scientific communities to facilitate genomic and genetic studies on rice biology.
Full-text · Article · Dec 2001 · Chinese Science Bulletin