Biomedical subjects

Dong Zhong

Publications and source records attributed to Dong Zhong.

3 recordsLinked to original sources

PubMed2004

Catalog of 162 single nucleotide polymorphisms (SNPs) in a 4.7-kb region of the HLA-DP loci in southern Chinese ethnic groups.

HLA class-II proteins are cell-surface molecules that present antigens to T cells, and their expressional regulation is crucial to the immune reaction. Sequence variation at the regulatory region can directly affect the gene expression level. We cloned and sequenced a 4.7-kb region containing the regulatory region, exon1, and partial intron1 of both HLA-DPA1 and DPB1 genes in 25 variable sequences from southern Chinese ethnic groups and got a high-density map of 162 single nucleotide polymorphisms (SNPs): seven in 5'-flanking regions, four in 5'-untranslated regions, and four in the coding regions. By comparing these data with SNPs in dbSNP database in the NCBI, 145 SNPs (89.5%) were novel. In addition, eight genetic variations of insertion-deletion polymorphisms (INDELs) were discovered within the 4.7-kb region. These high-resolution maps can be used as resources of markers for association studies of complex diseases, assessment of individuals' predisposition to diseases, and tailoring of therapies, as well as research markers for population genetics and evolution.

Base Sequence↗

PubMed2003

Comparing the base usage frequency between bacteria DNA double strand.

During the Evolution, effected by select pressure or nature mutation, the compositions of bacteria genomes is various. And many experiences prove that the genes between leading strand and lagging strand is distinctly in copy, transcription and repair. Some scholars presume that the bases distribution is difference between the two strand, to verify the guess, we using the technology of bioinformatics, compare the base usage between the DNA double strand in 17 species bacteria. The result show: 1. there is same bases usage frequency in coding sequence between leading strand and lagging strand 2. There also same bases usage frequency in first codon, second codon and third codon. It suggest that there is a equilibrium between the two strand by the effect of select pressure and nature mutation.

Bacteria↗

PubMed2003

[Construction and identification of the cDNA phage expression library for human colorectal cancer antigens].

OBJECTIVE: To construct a cDNA phage expression library for human colorectal carcinoma antigens. METHODS: After the total RNA was extracted from human colorectal cancer tissues, the single-strand and double-strand cDNA were synthesized through reverse transcriptase PCR and long-distance PCR, with the cDNA fragments smaller than 500 bp removed and the remaining cDNA combined with the right and left arms of dephosphorylated lambdaTriplEx2 phage vector. The recombinant phage were then packaged in vitro by MaxPlax Packaging extract, and a small portion of the packaged phage was used to infect E.coli XL1-Blue. Titer measurement was performed so as to determine the capacity of the library. SfiI restriction endonucleases was used to cut the recombined phage DNA in order to identify the size of inserted cDNA. RESULTS: The constructed cDNA phage expression library for human colorectal cancer antigens consisted of 2.39 x 10(6) pfu/ml bacteriophages with a recombination rate of 97.5% and the length of the inserted cDNA fragment ranged from 600 to 4,000 bp with an average of 1,400 bp. CONCLUSION: The cDNA phage expression library of human colorectal cancer antigens is successfully constructed to meet the currently recognized standards, and can be well applicable in screening cDNA-cloned genes of human colorectal cancer-associated antigens by immunoscreening.

Antigens, Neoplasm↗