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Biomedical subjects

Zhenyu Chen

Publications and source records attributed to Zhenyu Chen.

6 recordsLinked to original sources

[Population fluctuation of main pathogens and their antagonistic bacteria in cucumber rhizosphere].

The investigation on the population fluctuation of main pathogens Pythium spp. and Fusarium oxysporum f. cucumerinum in the rhizosphere of four cucumber varieties showed that there was a significant difference in population number of pathogens for different cucumber varieties and for different growth stages of the same variety, which was in accordance with the regular disease incidence pattern. The population number of Pythium spp. was significantly higher at cucumber creeping stage than at its other growth stages, while that of Fusarium oxysporum f. sp. cucumerinum was the highest at cucumber principal-fruiting stage. There was a closer positive relationship between two test pathogens and their antagonistic bacteria, with the correlation coefficient being 0.95 and 0.81, respectively.

Antibiosis↗

[Labeling of biocontrol agents ZJY-1 and ZJY-116 gfp gene and its ecological adaptability in cucumber rhizosphere].

The recombined plasmid pRP22-GFP contained with gfp gene and chloramphenicol resistant was successfully introduced into two biocontrol agents Brevibacillus brevis ZJY-1 and Bacillus subtilis ZJY-116. After seed inoculation, the survival and colonization of the two strains were studied by periodically retrieving the GFP-tagged strains in the cucumber rhizosphere based on the selective markers. The results showed that both the strains could successfully colonize in the rhizosphere during the whole life of cucumber, and a higher colonization level was observed during anthesis and fruition stages. In pot trials, they could migrate to the nearby non-inoculated spontaneous weed plants, and reestablish in the rhizosphere of plants subsequently grown in the same pot.

Adaptation, Physiological↗

[Frequency-domain analysis methods for single ion channel currents].

The frequency domain of single channel currents is analyzed by the power distribution function (PDF) constructed by the discrete wavelet transform (DWT) and power spectral density (PSD). The result shows that the power distribution function based on DWT is an effective frequency-domain analysis method for single channel currents.

Fourier Analysis↗

[Studies on antioxidant constituents from black tea].

Qimen black tea has strong inhibitory activity of canola oil oxidation. Four antioxidant compounds, theaflavin (TF1), theaflavin-3-gallate (TF2A), theaflavin-3'-gallate (TF2B) and theaflavin digallate (TF3), were isolated from acetic acetate extract of black tea by silica gel and sephadex LH-20 column chromatography. TF1, TF2A, TF2B and TF3, have stronger antioxidant activity than that of BHT (Butylated hydorxytoluene).

Antioxidants↗

Genetic, physical, and comparative map of the subtelomeric region of mouse Chromosome 4.

The subtelomeric region of mouse chromosome (Chr) 4 harbors loci with effects on behavior, development, and disease susceptibility. Regions near the telomeres are more difficult to map and characterize than other areas because of the unique features of subtelomeric DNA. As a result of these problems, the available mapping information for this part of mouse Chr 4 was insufficient to pursue candidate gene evaluation. Therefore, we sought to characterize the area in greater detail by creating a comprehensive genetic, physical, and comparative map. We constructed a genetic map that contained 30 markers and covered 13.3 cM; then we created a 1.2-Mb sequence-ready BAC contig, representing a 5.1-cM area, and sequenced a 246-kb mouse BAC from this contig. The resulting sequence, as well as approximately 40 kb of previously deposited genomic sequence, yielded a total of 284 kb of sequence, which contained over 20 putative genes. These putative genes were confirmed by matching ESTs or cDNA in the public databases to the genomic sequence and/or by direct sequencing of cDNA. Comparative genome sequence analysis demonstrated conserved synteny between the mouse and the human genomes (1p36.3). DNA from two strains of mice (C57BL/6ByJ and 129P3/J) was sequenced to detect single nucleotide polymorphisms (SNPs). The frequency of SNPs in this region was more than threefold higher than the genome-wide average for comparable mouse strains (129/Sv and C57BL/6J). The resulting SNP map, in conjunction with the sequence annotation and with physical and genetic maps, provides a detailed description of this gene-rich region. These data will facilitate genetic and comparative mapping studies and identification of a large number of novel candidate genes for the trait loci mapped to this region.

Animals↗

Hepatitis C virus genotyping: interrogation of the 5' untranslated region cannot accurately distinguish genotypes 1a and 1b.

Although the 5' untranslated region (5' UTR) is the most conserved region of the hepatitis C virus (HCV) genome, it has been suggested that interrogation of this region is sufficient for determination of the HCV genotype. We compared two methods of determination of the HCV genotype: (i) direct sequencing of the DNA of the NS-5b region and (ii) reverse line probe assay (LiPA; INNO-LiPA HCV II; Innogenetics N.V.) of the 5' UTR. There was 100% concordance between the two methods for genotype but only 80% concordance for subtype. A significant percentage of genotype 1a isolates were misclassified by LiPA as genotype 1b. Sequence analysis revealed that the only consistent difference in the 5' UTR for these genotype 1a isolates misclassified as genotype 1b was a single nucleotide (A/G) at position -99 of the HCV genome. All isolates with discordant results analyzed had a G at this position, consistent with LiPA determination of these samples as subtype 1b. However, sequence analysis of 222 nucleotides in the NS-5b region clearly identified all of these isolates as subtype 1a. Population distribution data from the University of Pittsburgh Medical Center of over 200 samples analyzed by sequencing of the NS-5b region and over 1,000 samples analyzed by LiPA also indicated that INNO-LiPA HCV II cannot accurately differentiate HCV genotype 1a isolates from HCV genotype 1b isolates. We provide evidence that the A/G at position -99 represents a sequence polymorphism in the HCV genome that cannot differentiate subtype 1a from subtype 1b isolates. In conclusion, the 5' UTR is not heterogeneous enough for use in determination of the HCV subtype and cannot be used for differentiation of HCV genotypes 1a and 1b.

5' Untranslated Regions↗