Sequence Analysis of the Internal Transcribed Spacer of Ribosomal DNA in the Genus Rhizopus

The internal transcribed spacer (ITS) regions including the 3'-end of 18S rRNA gene, 5.8S rRNA gene and the 5'-end of the 28S rRNA gene of Rhizopus spp. were amplified by PCR and analyzed by DNASIS program. Length polymorphism of these region ranged from 564 bp in R. oryzae to 789bp in R. stolonifer. The length and sequence of 5.8S was very conserved with 154~155 bp. The sequence of ITS2 was more variable than that of ITS1. The base substitution rates were ranged from 0 to 0.6069 per site, and higher rate was found in R. stolonifer. In general, transition was usually more frequent than transversion. On the basis of sequencing results, four groups were clustered with value of 61.9% similarity; R. oryzae, R. microspores, R. homothallicus, and R. stolonifer groups.

Nucleotide Divergence Analysis of IGS Region in Fusarium oxysporum and its formae speciales Based on the Sequence

The intergenic spacer(IGS) sequence of Fusarium oxysporum have been reported to provide reliable information concerning intraspecific variation and phylogeny of fungal species. The eleven strains of Fusarium oxysporum and its formae speciales belonging to section Elegans were compared with sequencing analysis. The direct sequencing of partial IGS was carried out using PCR with primer NIGS1(5'-CTTCGCCTCGATTTCCCCAA-3')/NIGS2(5'-TCGTCGCCGACAGTTTTCTG-3') and internal primer NIGS3(5'-TCGAGGATCGATTCGAGG-3')/NIGS4(5'-CCTCGAATCGATCCTCGA-3'). A single PCR product was found for each strain. The PCR fragments were sequenced and revealed a few within species polymorphisms at the sequence level. The size of partial IGS sequencing of F. oxysporum was divided into three groups; 526~527 bp including F. o. f. sp. chrysanthemi, cucumerinum, cyclaminis, lycopersici, and fragariae; 514~516 bp including F. o. f. sp. lilii, conglutinans, and raphani; 435 bp for F. o. f. sp. cucumerinum from Korea. Sequence analysis of PCR products showed that transitions were more frequent than transversions as well as the average numbers of substitution per site were range 0.41% to 3.54%.

Molecular Characterization of Fusarium solani and its Formae Speciales Based on Sequences Analysis of the Internal Transcribed Spacer (ITS) Region of Ribosomal DNA

The sequences of the internal transcribed spacer (ITS) and 5.8s ribosomal RNA gene (rDNA) from Fusarium solani and its four formae speciales belonging to section Martiella was determined to investigate intraspecific divergence of the ITS regions. The length of the 5.8S, a coding region, was equally 158 bp at all isolates, whereas the variable range of ITS region was shown at 147~152 bp (ITS1) and 148~174 bp (ITS2). According to the maximum-matching method, the matching percentage was 94~100 at 5.8s rDNA, 77~97 at ITS1, and 67~97 at ITS2, respectively. In dendrogram based on the alignment of the ITS sequence data, F.solani f. sp. piperis was distinguished from other isolates belonging to the same species and nucleotide identity was considerably low (41.5%).

Apoptosis Induction of Stomach Cancer Cell by TNF alpha and TGFbeta / 대한암학회지

PURPOSE: Apoptosis is a physiological mechanism for deleting cells from the body for development and homeostasis. Exogenous cytokines such as tumor necrosis factor alpha (TNFalpha) and transforming growth factor beta (TGF beta) are known to modulate apoptosis, thus can provide a new therapeutic modality for various malignancies. We studied whether TNFalpha or TGFbeta can induce apoptosis or exert antiproliferative effect on human gastric cancer cell line (AGS) and which genes are involved in the cytokine-induced apoptotic pathway. MATERIALS AND METHODS: To examine the effect of TNFalpha or TGF beta on AGS cell line (human gastric adenocarcimoma), we performed following tests; MTT test, trypan blue dye exclusion assay and colony forming efficiency. Total DNA was extracted from the TNFalpha-treated AGS cells and DNA ladder was detected as the hallmark of apoptosis, and flow cytometry analysis was performed for another apoptotic index. The effects of TNFalpha on c-myc expression was observed using RT-PCR. RESULTS: TNFalpha suppressed AGS cell growth, in a time- and dose-dependent manner, but TGFbeta had no effect on AGS cell growth. Electrophoretic analysis of total cellular DNA revealed the pattern of internucleosomal DNA cleavage, which is specific for apoptosis and the effect was observed from 24 to 72 hrs after 50 ng/ml TNFalpha treatment. Time-dependent increse of apoptotic cells by TNFalpha was detected by flow cytometry analysis. Morphological changes such as cell to cell contacts and extension of cell processes were observed in TNFalpha-treated AGS cells. RT-PCR using c-myc primers showed thatthe mRNA levels were increased 6 hrs after TNFalpha treatment and persisted for 72 hrs. CONCLUSION: It is suggested that TNFalpha, but not TGF beta, functions as an important inducer of apoptosis in AGS cell line, and c-myc may function as a critical endogenous activator of the pathway leading to cell death of AGS cells.