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Tao Li

Publications and source records attributed to Tao Li.

At least 217 records · Page 12Linked to original sources
PubMed2002

Sequence and analysis of rice chromosome 4.

Rice is the principal food for over half of the population of the world. With its genome size of 430 megabase pairs (Mb), the cultivated rice species Oryza sativa is a model plant for genome research. Here we report the sequence analysis of chromosome 4 of O. sativa, one of the first two rice chromosomes to be sequenced completely. The finished sequence spans 34.6 Mb and represents 97.3% of the chromosome. In addition, we report the longest known sequence for a plant centromere, a completely sequenced contig of 1.16 Mb corresponding to the centromeric region of chromosome 4. We predict 4,658 protein coding genes and 70 transfer RNA genes. A total of 1,681 predicted genes match available unique rice expressed sequence tags. Transposable elements have a pronounced bias towards the euchromatic regions, indicating a close correlation of their distributions to genes along the chromosome. Comparative genome analysis between cultivated rice subspecies shows that there is an overall syntenic relationship between the chromosomes and divergence at the level of single-nucleotide polymorphisms and insertions and deletions. By contrast, there is little conservation in gene order between rice and Arabidopsis.

Arabidopsis↗
PubMed2002

[Site-directed mutagenesis of atrial natriuretic peptide gene and effect of the mutations on its diuretic activity in nephrotic rats].

OBJECTIVE: To prolong the half-life and enhance the biological activity of the human atrial natriuretic peptide (hANP), a peptide hormone, which is synthesized and released mainly by cardiac atrial myocytes and possesses potent natriuretic, diretic, and vasorelaxant properties. METHODS: The site-directed mutation technique based on polymerase chain reaction was performed to get the mutant of the human ANP gene (mhANP), and the retroviral expression vector, pLHY24, in which mhANP gene is under the transcriptional control of the human cytomegalovirus promoter, was constructed. The naked plasmid DNA of pLHY24 and positive control vector, pLHY19, in which the wild-type hNAP gene is in the same conditions as mhANP gene in pLHY24, and negative control vector, pLNCX without purpose gene, at a dose of 5 mg/kg body weight was injected intramuscularly into the rats with experimental renal disorder induced with adriamycin (ADR), respectively. RESULTS: DNA sequencing result proved that the respected mhANP gene with the point mutations of TTC(131)/Phe-->TCC/Ser and ATG(135)/Met-->ATA/Ile has been obtained. In comparison with negative control group (87 +/- 7.1 pg/ml), a single intramuscular injection of expression vector harboring mhANP or hANP gene resulted in an obvious increase in plasma level of mhANP (107 +/- 7.8 pg/ml, t = 4.65, P < 0.01) or hANP (113 +/- 8.6 pg/ml, t = 5.71, P < 0.01) 5 days after injection. A significant elevation in the ratio of urine volume to body weight was occurred after both of mhANP gene and hANP gene delivery as compared with negative control and the effect lasted for more than 15 days. The diuretic activity of mhANP gene delivery was 1.6-, 2.0-, and 1.9-fold higher than that of hANP gene 5, 10, and 15 days after gene transfer, respectively. However, there were no statistical differences in the concentrations of K(+) and Na(+) in urine. CONCLUSIONS: Both of mhANP and hANP gene delivery into the rats with experimental nephropathy could improve their directic function obviously and the diuretic activity of the former is stronger than that of the latter significantly.

Animals↗
PubMed2002

[Hypotensive effect of encapsulated genetically engineered fibroblasts expressing mutant atrial natriuretic peptide in hypertensive rats].

OBJECTIVE: To study the inhibitive effect of subcutaneous implantation of capsule filled with fibroblasts engineered to secrete the mutant human atrial natriuretic peptide (mhANP) on blood pressure in young spontaneously hypertensive rats (SHR) and to explore the feasibility of gene therapy for the treatment of hypertension. METHODS: A recombinant retroviral vector pLHY24 bearing mhANP cDNA was constructed. Primary fibroblasts derived from the skin of new born SHR were cultured and transfected with the vector pLHY24 to establish a genetically modified fibroblast line or transfected with the blank vector pLNCX. Then the two kinds of cell culture were put into specially made capsules with microholes. The capsules filled with the genetically modified allogenic fibroblasts and those with blank vector were implanted into the dorsal subcutaneous tissues of two groups of 10 young SHR respectively. The plasma ANP, blood pressure, urine volume, potassium and sodium concentrations in urine, and body weight were determined every week for 7 weeks. RESULTS: After delivery of retroviral vector bearing mhANP gene into the packaging cell PA317 and the primary fibroblasts, immunoreactive mhANP were detected in the cell culture medium at the concentration of (5.84 +/- 0.07) and (13.37 +/- 2.36) ng.10(-6) cells.24 h(-1) respectively. One week after implantation of the genetically modified allogenic fibroblasts the plasma level of mhANP was 131 pg/ml +/- 8 pg/ml, significantly higher than that in control group (104 pg/ml +/- 7 pg/ml, t = 8.62, P < 0.001). Although the blood pressure increased along with aging after the gene transfer, an obvious delay of blood pressure increase was seen significantly lower in test group [from (129 +/- 9) to (169 +/- 9) mm Hg] than that in the control group [from (145 +/- 10) to (181 +/- 9) mm Hg, P < 0.05 or 0.01]. A maximal blood pressure reduction of 28 mm Hg in young SHR was observed 7 days after transplantation as compared with controls. In addition, there was an obvious increase in urine volume of test group 2 weeks after transplantation and the effect lasted for more than 2 weeks. However, there were no statistical differences in body weight and the concentrations of K(+) and Na(+) in urine. CONCLUSION: Subcutaneous implantation of the encapsulated genetically modified fibroblasts engineered to secrete mutant ANP causes a lowering effect of blood pressure in young SHR.

Animals↗
PubMed2002

Allelic association analysis of the dopamine D2, D3, 5-HT2A, and GABA(A)gamma2 receptors and serotonin transporter genes with heroin abuse in Chinese subjects.

Five candidate genes, the receptors DRD2, DRD3, HTR2A and GABA(A)gamma2, and the serotonin transporter (5-HTT) were analyzed for association with heroin abuse. We examined three polymorphisms (promoter - 141DeltaC, Ser311Cys, and TaqI) in the DRD2 gene, one polymorphism (Ser9Gly) in the DRD3 gene, two polymorphisms (promoter - 1438G/A and T102C) in the HTR2A gene, two polymorphisms (VNTR and Del/Ins) in 5-HTT gene, and one polymorphism (G3145A) in GABA(A)gamma2 gene in 121 Chinese heroin addicts and 194 controls. None of the polymorphisms differed significantly for allele, genotype, or haplotype frequencies, except for the DRD2 promoter polymorphism - 141DeltaC (genotype-wise and allele-wise, P = 0.05, uncorrected). An additional 344 subjects with heroin abuse and 104 controls were investigated for the - 141DeltaC polymorphism. In the second sample, there were no significant difference of genotype or allele frequencies between subjects with heroin abuse and normal controls. When we divided the sample by route of administration into nasal inhalers and IM or IV injectors, however, it produced a significant difference between inhalers of heroin and controls (genotype-wise, P = 0.006, allele-wise, P = 0.016) but not for injectors of heroin (genotype-wise, P = 0.81, allele-wise, P = 0.69). We also found that LD between all polymorphisms we examined in the gene was weak, possibly explaining why we see association of this polymorphism with heroin abuse but not with other markers in the gene. Overall our results indicates that the HTR2A, 5-HTT, DRD3 and GABA(A)gamma2 genes are not likely to be a major genetic risk factor for heroin abuse in this population, with the exception of possible association between nasal inhalation and DRD2 promoter - 141DeltaC polymorphism.

Adolescent↗
PubMed2002

A draft sequence of the rice genome (Oryza sativa L. ssp. indica).

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.

Arabidopsis↗
PubMed2002

An imprinted PEG1/MEST antisense expressed predominantly in human testis and in mature spermatozoa.

PEG1 (or MEST) is an imprinted gene located on human chromosome 7q32 that is expressed predominantly from the paternal allele. In the mouse, Peg1/Mest is associated with embryonic growth and maternal behavior. Human PEG1 is transcribed from two promoters; the transcript from promoter P1 is derived from both parental alleles, and the transcript from P2 is exclusively from the paternal allele. We characterized the P1 and P2 transcripts in various normal and neoplastic tissues. In the normal tissues, PEG1 was transcribed from both promoters P1 and P2, whereas in six of eight neoplastic tissues, PEG1 was transcribed exclusively from promoter P1. Bisulfite sequencing demonstrated high levels of CpG methylation in the P2 region of DNA from a lung tumor. In the region between P1 and P2, we identified a novel transcript, PEG1-AS, in an antisense orientation to PEG1. PEG1-AS is a spliced transcript and was detected as a strong 2.4-kilobase band on a Northern blot. PEG1-AS and PEG1 P2-sense transcript were expressed exclusively from the paternal allele. Fragments of DNA from within the 1.5-kilobase region between PEG1-AS and the P2 exon were ligated to a pGL3 luciferase reporter vector and transfected into NCI H23 cells. This DNA exhibited strong promoter activity in both the sense and antisense directions, indicating that PEG1-AS and P2 exon share a common promoter region. Treatment of the transfected DNA fragments with CpG methylase abolished the promoter activity. Of interest, PEG1-AS was expressed predominantly in testis and in mature motile spermatozoa, indicating a possible role for this transcript in human sperm physiology and fertilization.

Alleles↗
PubMed2002

Comparative study of fast MR imaging: quantitative analysis on image quality and efficiency among various time frames and contrast behaviors.

The purpose of this study is to quantitatively compare the image quality and efficiency provided by widely available fast MR imaging pulse sequences. A composite phantom with various T1 and T2 values and subjected to periodic motion was imaged at 1.5 T. The fast MRI sequences evaluated included fast spin-echo (FSE), single shot fast spin-echo (SSFSE), echo-planar imaging (EPI), multi-slice gradient recalled (MPGR), fast MPGR (FMPGR), and fast multi-slice spoiled gradient echo (FMPSPGR). T1-weighted (T1WI), T2-weighted (T2WI), proton-density-weighted (PDWI), and T2*-weighted (T2*WI) images were evaluated in breath-hold and non-breath-hold time frames. Analysis included measurement of image signal-to-noise ratio (SNR), contrast-to-noise ratio (CNR), nonuniformity, ghosting ratio, SNR per unit time and CNR per unit time. Among fast T2WI sequences, FSE with breath-hold time frame resulted in the highest image quality and in superior SNR and CNR efficiency by a factor of 5 or 6 as compared with conventional spin echo sequence. Among fast T1WI sequences, FMPGR and FMPSPGR both with non-breath-hold time frame produced the highest image quality and SNR and CNR efficiency by a factor of greater than 5 as compared with conventional spin echo. Among fast PDWI and T2*WI sequences, FSE produced the highest SNR and CNR, and was maximally efficient with a factors of greater than 6 as compared with conventional spin echo.

Echo-Planar Imaging↗
PubMed2002

PGAAS: a prokaryotic genome assembly assistant system.

MOTIVATION: In order to accelerate the finishing phase of genome assembly, especially for the whole genome shotgun approach of prokaryotic species, we have developed a software package designated prokaryotic genome assembly assistant system (PGAAS). The approach upon which PGAAS is based is to confirm the order of contigs and fill gaps between contigs through peptide links obtained by searching each contig end with BLASTX against protein databases. RESULTS: We used the contig dataset of the cyanobacterium Synechococcus sp. strain PCC7002 (PCC7002), which was sequenced with six-fold coverage and assembled using the Phrap package. The subject database is the protein database of the cyanobacterium, Synechocystis sp. strain PCC6803 (PCC6803). We found more than 100 non-redundant peptide segments which can link at least 2 contigs. We tested one pair of linked contigs by sequencing and obtained satisfactory result. PGAAS provides a graphic user interface to show the bridge peptides and pier contigs. We integrated Primer3 into our package to design PCR primers at the adjacent ends of the pier contigs. AVAILABILITY: We tested PGAAS on a Linux (Redhat 6.2) PC machine. It is developed with free software (MySQL, PHP and Apache). The whole package is distributed freely and can be downloaded as UNIX compress file: ftp://ftp.cbi.pku.edu.cn/pub/software/unix/pgaas1.0.tar.gz. The package is being continually updated.

Algorithms↗
PubMed2002

A fine physical map of the rice chromosome 4.

As part of an international effort to completely sequence the rice genome, we have produced a fine bacterial artificial chromosome (BAC)-based physical map of the Oryza sativa japonica Nipponbare chromosome 4 through an integration of 114 sequenced BAC clones from a taxonomically related subspecies O. sativa indica Guangluai 4 and 182 RFLP and 407 expressed sequence tag (EST) markers with the fingerprinted data of the Nipponbare genome. The map consists of 11 contigs with a total length of 34.5 Mb covering 94% of the estimated chromosome size (36.8 Mb). BAC clones corresponding to telomeres, as well as to the centromere position, were determined by BAC-pachytene chromosome fluorescence in situ hybridization (FISH). This gave rise to an estimated length ratio of 5.13 for the long arm and 2.9 for the short arm (on the basis of the physical map), which indicates that the short arm is a highly condensed one. The FISH analysis and physical mapping also showed that the short arm and the pericentromeric region of the long arm are rich in heterochromatin, which occupied 45% of the chromosome, indicating that this chromosome is likely very difficult to sequence. To our knowledge, this map provides the first example of a rapid and reliable physical mapping on the basis of the integration of the data from two taxonomically related subspecies.

Chromosomes↗
PubMed2002

Differential expression and localization of Mn and Fe superoxide dismutases in the heterocystous cyanobacterium Anabaena sp. strain PCC 7120.

Superoxide dismutases (Sods) play very important roles in preventing oxidative damages in aerobic organisms. The nitrogen-fixing heterocystous cyanobacterium Anabaena sp. strain PCC 7120 has two Sod-encoding genes: a sodB, encoding a soluble iron-containing Sod (FeSod), and a sodA, encoding a manganese-containing Sod (MnSod). The FeSod was purified and characterized. A recombinant FeSod was also obtained by overproduction in Escherichia coli. Immunoblot study of the FeSod during induction of heterocyst differentiation showed that the cells produced six- to eightfold more FeSod 8 h after a shift from a nitrogen-replete condition to a nitrogen-depleted condition. However, the amount of FeSod protein in filaments with mature heterocysts was the same as that in filaments grown with combined nitrogen. Superoxide anion-generating chemicals such as methyl viologen did not induce upregulation of the sodB gene expression. The predicted preprotein of the sodA gene has a leader peptide and a motif for membrane attachment at the N terminus of the mature protein. Activity staining after gel electrophoresis of the purified thylakoid membranes showed that most of the MnSod in Anabaena sp. strain PCC 7120 was located on thylakoids toward the lumenal side. Expression of the sodA gene in E. coli shows that the leader peptide was required for its activity and the membrane localization of the MnSod. Northern hybridization detected one 0.82-kb transcript of sodA. The sodA gene was upregulated by methyl viologen, whereas its amount was unchanged during heterocyst differentiation. Immunoblotting and activity staining showed that isolated heterocysts contained a lower but still significant amount of FeSod, suggesting that its function is required in heterocysts. No MnSod was observed in isolated heterocysts. These results show that the two different Sod proteins have differentiated roles in Anabaena sp. strain PCC 7120.

Amino Acid Sequence↗
PubMed2002

Study of efferent tube suspension as a continent diversion mechanism. an experimental study in dogs.

PURPOSE: To construct a reliable continent tube, which is easy to catheterize and surgically simple. MATERIALS AND METHODS: 8 adult female mongrel dogs underwent a procedure in which an ileal segment was tapered as an efferent tube. The tapered ileum was fixed to the back surface of the rectus muscle with a polyester taper 1.5 cm in width and a suspension tension of 400 g. The internal orifice of the tapered ileum was anastomosed to the bladder and the external orifice of the tapered ileum was brought out to the abdominal skin. Urodynamic and radiological studies were carried out postoperatively in all dogs. RESULTS: All stomas in dogs could be easily catheterized with a 14-french catheter. Urodynamic study of the efferent tubes showed that the maximum closure pressure ranged from 117 to 157 (mean 136.75) cm water. Retrograde radiogram of the efferent tubes showed perfect canalization without stenosis. CONCLUSION: This study suggests that the continent mechanism of the tapered ileum can be greatly enhanced by a suspension technique.

Animals↗
PubMed2002

[Transmission disequilibrium test of DRD4 exon III 48bp variant number tandem repeat polymorphism and tic disorder].

OBJECTIVE: To investigate whether DRD4 exon III48 bp variant number tandem repeat(VNTR) polymorphism is associated with tic disorder. METHODS: One hundred and twenty-two nucleus families were collected using Structured clinical interview for genetic study of Tourette syndrome and related disorders for family-based association analysis of tic disorder and DRD4 exon III 48bp VNTR polymorphism. One hundred and twenty-two trios were divided into two groups: tic disorder group (82 trios of Tourette syndrome or chronic tic disorder, TS&CT) and tic disorder accompanied with attention deficit and hyperactivity disorder (ADHD) group (40 trios of Tourette syndrome or chronic tic disorder accompanied with ADHD, TS&ADHD). Transmission disequilibrium test (TDT), in addition to polymerase chain reaction and VNTR technique were conducted in 122 trios. RESULTS: There exist 5 alleles at this polymorphic locus in this sample including DRD4 exon III 48bp 2-6 repeats. No transmission disequilibrium was found between DRD4 exon III 48 bp VNTR and tic disorder (chi square=7.44, P 0.12); however, when the sample was divided into two groups, transmission disequilibrium was noticed between the cases of TS&ADHD and this locus by overall allele-wise analysis (chi square=11.74, P 0.02), and there exists transmission disequilibrium exclusively between 5 or 6 repeats of 48bp VNTR(longer alleles) by allele-wise analysis (chi square=10.57, P 0.032, chi square=6.13, P 0.01). No transmission disequilibrium was seen between TS&CT and DRD4 exon III 48bp VNTR(chi square=3.38, P 0.50). CONCLUSION: The results of this study have revealed an association between the longer alleles of DRD4 exon III 48bp VNTR polymorphism and tic disorder accompanied with ADHD, thus suggesting a possible genetic risk factor of tic disorder accompanied with ADHD in Chinese.

Adolescent↗
PubMed2002

Acetazolamide suppresses tumor metastasis and related protein expression in mice bearing Lewis lung carcinoma.

AIM: To study the suppressing effect of acetazolamide on tumor metastasis in vivo and observe the protein alteration of lung in mice bearing Lewis lung carcinoma. METHODS: The functional role of aquaporin-1 (AQP1) was investigated in tumor tissues by SDS-PAGE and Western blot. The effect of acetazolamide on tumor metastasis was analyzed by Lewis-lung-carcinoma model. Differential protein was identified by SDS-PAGE, isoelectrofocusing (IEF) methods, and peptide mass fingerprinting (PMF). RESULTS: Acetazolamide (40 mg/kg/d po for 21 d) dramatically reduced the numbers of lung metastasis after sc inoculating Lewis lung carcinoma. The inhibition rate of lung metastases was 83.9 %. Simultaneously, the AQP1 protein level and actin-cytoplasmic in lungs containing metastatic tumor deposits were found to be higher than that in the normal tissue. After treated with acetazolamide for 21 d, the expression of AQP1 was obviously inhibited. CONCLUSION: Acetazolamide can suppress tumor metastasis, at least in part, by inhibiting the expression of AQP1. AQP1 and actin-cytoplasmic may be new prognostic molecules as well as new therapeutic targets for the prevention and treatment of metastatic tumor.

Acetazolamide↗
PubMed2002

[A linkage analysis of quantitative trait loci for familial schizophrenia on chromosome 1].

OBJECTIVE: To explore the molecular genetic relationship between chromosome 1 and quantitative trait loci for familial schizophrenia. METHODS: A series of assessment scales included positive and negative syndrome scale (PANSS), global assessment of functional scale (GAFS), premorbid schizoid and schizotypal traits scale (PSST), premorbid social adjustment scale (PSA) were applied to quantify the phenotypes of schizophrenia. Non-parametric linkage analysis of quantitative traits was conducted in 32 multiplex pedigrees with schizophrenia by using 29 microsatellite makers on chromosome 1. RESULTS: Haseman-Elston quantitative trait analysis detected a maximum Traditional H-E Lods of 1.73 and a maximum EH H-E Lods of 1.65 of negative symptoms (PANSS-N ) at 147.64 cM, which was overlapped to the positive region of 1q21-23 in qualitative linkage analysis. CONCLUSION: The results suggest there might be an independent quantitative trait locus of negative symptoms on 1q21-23 for familial schizophrenia.

Chromosomes, Human, Pair 1↗
PubMed2002

[Linkage analysis of susceptibility genes for familial schizophrenia on chromosome 1 in Chinese population].

OBJECTIVE: To explore the molecular genetic relationship between chromosome 1 and susceptibility genes for familial schizophrenia in Chinese population. METHODS: A genome scanning was conducted in 32 multiplex pedigrees from Chinese population by using 29 microsatellite markers on chromosome 1. RESULTS: Multipoint parametric analysis detected a maximum heterogenicity Lod of 1.70 at 262.52 cM under a recessive model; multipoint non-parametric analysis detected a maximum non-parameter linkage (NPL) of 1.71 (P=0.046) at 262.52 cM, then 1.37 (P=0.086) at 149.70 cM, corresponding to marker D1S206 and D1S425 respectively. CONCLUSION: These results give further supports to the presence of susceptibility genes on chromosome 1q for familial schizophrenia.

Adult↗
PubMed2002

[Association study of heroin-dependence and -287 A/G polymorphism of catechol-O-methyltransferase gene].

OBJECTIVE: To detect the relationship between heroin-dependence and -287 A/G polymorphism of catechol-O-methyltransferase(COMT) gene. METHODS: Genotype and allele frequencies of -287 A/G polymorphism of COMT gene were examined in 268 heroin-dependent subjects and 177 normal controls. RESULTS: Weak but significant difference in genotype of -287 A/G polymorphism of COMT gene was observed between heroin-dependent subjects and controls (chi(2)=7.41, P=0.025), and genotype AA was higher in the former. The frequency of allele A of -287 A/G polymorphism of COMT gene was also significantly higher in heroin-dependent subjects than in the controls (chi(2)=5.69, P=0.017). CONCLUSION: The results suggested that liability to heroin-dependence was associated with -287 A/G polymorphism of COMT gene.

Adolescent↗
PubMed2002

[Effects of silkworm pupa oil on serum lipids level and platelet function in rats].

To observe the effects of silkworm pupa oil on serum lipids level and platelet function in rats, according to serum TG, TC level, 40 male Wistar rats are divided into four groups (normal control group, high fat control group, silkworm pupa oil group and silkworm pupa oil + VE group). The rats are fed different diets and six weeks later, serum lipids level and platelet function are measured. The results show that (1) Compared with high fat control group, serum TC, TG, LDL-C level, AI value, Platelet aggregability, plasma TXB2 level and T/P ratio decrease significantly while HDL-C level and 6-k-PGF1 level increase in silkworm pupa oil group; (2) Serum TC, LDL-C level, T/P ratio and platelet aggregability are significantly lower in silkworm pupa oil + VE group than in silkworm pupa oil group. It is suggested that silkworm pupa oil rich in alpha-linolenic acid can reduce serum lipids level and inhibit platelet aggregation, which is more effective with the supplementation with VE.

Animals↗