• Mycobiology
• /
• v.29 no.1
• /
• pp.1-6
• /
• 2001

Nine species of genus Ganoderma collected in Korea and abroad including Ganoderma lucidum complex and G. lucidum were compared by investigating growth characteristics. In the bottle culture, the mycelial growth periods of G. lucidum from Taiwan and North America was 26 to 30 days compared to that of Korean G. lucidum, which was 30 to 32 days. Cultivation period of Taiwan and North American isolates was 30 to 32 days which were 11 to 17 days shorter than those of Korean isolates. Biological efficiency of Taiwan and North American isolates were ranged from 3.3 to 5.5%, which were apparently lower than that of Korean isolates which ranged from 6.2 to 9.4%. Korean isolates had longer stipes($15{\sim}40$ mm) and more number of pileus($4{\sim}6$/bottle) than those of Taiwan and North American isolates. The G. lucidum isolates collected from Korea will be regarded as the independent species from the G. lucidum collected from Taiwan and North America since, the G. lucidum from Korea showed much different growth characteristics in various aspects compared to the G. lucidum from Taiwan and North America.

• Mycobiology
• /
• v.35 no.4
• /
• pp.230-234
• /
• 2007

In order to breed a Cordyceps bassiana isolate that stably forms fruiting body in artificial cultivation, isolates derived from subculturing and single spores were tested through mating. From C. bassiana EFCC 783, three subcultured isolates EFCC 2830, EFCC 2831 and EFCC 2832 were obtained and fourteen single conidial isolates were obtained from these three subcultured isolates. Two different morphological types were found in the fourteen single conidial isolates. One type was able to form synnemata and another type was not able to form synnemata. Since switch of morphological type was not observed despite their continuous subculturing, cross was performed between the two types and the formation of fruiting body was examined. Ascospores were obtained from a selected fruiting body formed by hybrid of the cross. Self-cross and combinational cross of the ascospore-derived isolates generated hybrids that stably produce high quality fruiting body in artificial media.

• The Plant Pathology Journal
• /
• v.28 no.4
• /
• pp.390-400
• /
• 2012

Eight potato-producing provinces of Iran were surveyed during the growing seasons of 2004-2006 to detect the presence of Tomato yellow fruit ring virus (TYFRV), a tentative species in the genus Tospovirus. A total of 1,957 potato leaf samples were collected from plants with tospovirus-like symptoms of chlorotic or necrotic spots, chlorosis and necrosis. The samples were tested by enzyme-linked immunosorbent assay using TYFRV-specific antibodies. Among those tested, 498 samples (25.4%) were found to be infected with the virus. The virus was detected in 72.4% of the potato fields in all provinces surveyed. Thirteen potato isolates of TYFRV were selected for further biological and molecular studies. Based on their reactions on Nicotiana tabacum plants, the isolates were separated into two groups, namely L (local infection) and N (systemic infection). The nucleotide sequences of the nucleoprotein (N) genes of the isolates were determined and compared with the homologous sequences in Genbank. No recombination evidence was found in the isolates using different recombination-detecting programs. In the phylogenetic tree, the potato isolates fell into two major groups: IRN-1 and IRN-2 corresponding to the two biologically separated groups. This study shows for the first time the biological and phylogenetic relationships of geographically distant TYFRV isolates from potatoes in the mid-Eurasian country of Iran.

• Clinical and Experimental Pediatrics
• /
• v.48 no.11
• /
• pp.1206-1211
• /
• 2005

Purpose : Pneumococcal protein vaccine based on pneumococcal surface protein A (PspA) is in development with the potential to offer a broad range of protection against different strains. PspA elicits protection in mice against fatal sepsis as well as carriage and lung infection. This study was performed to investigate the frequency of PspA families among Streptococcus pneumoniae recovered from Korean children and adults. Methods : A total of 89 pneumococcal isolates was included in the study. They were capsule serotyped by the slide agglutination assay with commercial antisera. PspA families were determined with polymerase chain reaction using the pair of primers for family 1 and family 2. Results : Seventeen pneumococcal serotypes were found in a total of 89 isolates. PspA typing was able to ascertain 79 of the 89 isolates (88.8 percent). Among these, 20 (22.5 percent) isolates were family 1 PspA, 59 (66.3 percent) were family 2. Moreover, because 9 (10.1 percent) isolates were of positive reactions for both, families 1 and 2 primers, the potential coverage of PspA vaccine was 98.9 percent. PspA families were not associated with age group, source of isolates, or penicillin susceptibility. However, the relative distribution of family 1 isolates to family 2 isolates was significantly different over capsular serotypes. Conclusion : The finding that 98.9 percent of Korean isolates belonging to PspA families 1 and 2 support the hypothesis that a human PspA vaccine covering a few PspA families could be broadly effective. The monitoring of the PspA families derived from large population-based isolates will be necessary in the context of vaccine development.

• Restorative Dentistry and Endodontics
• /
• v.25 no.4
• /
• pp.587-598
• /
• 2000

Urea in the oral cavity is hydrolyzed mainly by bacterial ureases to ammonia, which in turn, raises pH of the oral environment, maintaining oral pH homeostasis, thereby inhibiting dental caries. Streptococcus salivarius has been shown to be a major contribution to oral ureolysis. Synthesis of urease by S. salivarius appears to be constitutive, but can be greatly enhanced in the acidic environment. It has been presumed that ureolytic activity of S. salivarius strains isolated from caries-active site is greater than that of strains from caries-free site. However, no in vivo study has supported the presumption. The present study was performed to observe the ureolytic activity of S. salivarius strains isolated from different environments in the same individual, finding out whether the ureolytic activity is related to dental caries. For the purpose, S. salivarius strains were isolated from caries-active site (>C2), a caries-free site of the tooth, and the dorsum of the tongue of each of 50 patients having decayed teeth. The strains isolated from the patients who harbored S. salivarius in more than two sites were selected and then their ureolytic activities were measured. In order to examine clonal diversity of the strains, their ureC genes were amplified by polymerase chain reaction (PCR) and then restricted with EcoRV, and the protein profiles of the strains were compared by SDS-PAGE. The results were as follows: 1. Of 50 patients, 13 patients harbored S. salivarius in more than two sites; a total of 61 S. salivarius strain were isolated from the patients and selected for the study. 2. Of 17 isolates from the caries-active site of 9 patients harboring S. salivarius in more than two sites including carious lesion, 10 (58.8%) showed a high ureolytic activity (> 200 ${\mu}mol/min/mg$). While, 19 out of 44 isolates (43.2%) from the caries-free site of the teeth and the dorsum of the tongues of 13 patients were the strains with a high ureolytic activity. 3. Of 9 patients harboring S. salivarius in more than two sites including caries-active site. 6 patients were found to have the strains in the caries-active site showing a lower ureolytic activity than the strains in the other sites. 4. Of 34 isolates with ureolytic activity higher than 40 ${\mu}mol/min/mg$, 32 isolates produced 0.54-Kbp PCR products regardless of the sites of bacterial collection. In contrast, of 27 isolates with ureolytic activity lower than 40${\mu}mol/min/mg$, 26 isolates yielded 1.3-Kbp PCR products or none regardless of the sites. 5. Different clonal types of S. salivarius with relatively higher and lower ureolytic activities were found in the same individuals and even in the same sites. 6. None of strains showing different ureolytic activity appeared to be the same clonal type. The overall results suggest that ureolytic activity of the isolates does not appear to be related to differences of the environments but related to their own genetic traits.

• Parasites, Hosts and Diseases
• /
• v.53 no.3
• /
• pp.253-258
• /
• 2015

Toxoplasma gondii, an obligate intracellular protozoan parasite of the phylum Apicomplexa, can infect all warm-blooded vertebrates, including humans, livestock, and marine mammals. The aim of this study was to investigate whether superoxide dismutase (SOD) of T. gondii can be used as a new marker for genetic study or a potential vaccine candidate. The partial genome region of the SOD gene was amplified and sequenced from 10 different T. gondii isolates from different parts of the world, and all the sequences were examined by PCR-RFLP, sequence analysis, and phylogenetic reconstruction. The results showed that partial SOD gene sequences ranged from 1,702 bp to 1,712 bp and A + T contents varied from 50.1% to 51.1% among all examined isolates. Sequence alignment analysis identified total 43 variable nucleotide positions, and these results showed that 97.5% sequence similarity of SOD gene among all examined isolates. Phylogenetic analysis revealed that these SOD sequences were not an effective molecular marker for differential identification of T. gondii strains. The research demonstrated existence of low sequence variation in the SOD gene among T. gondii strains of different genotypes from different hosts and geographical regions.

• Parasites, Hosts and Diseases
• /
• v.47 no.2
• /
• pp.139-144
• /
• 2009

The aim of the present study was to investigate antimalarial drug pressure resulting from the clinical use of different antimalarials in Thailand. The phenotypic diversity of the susceptibility profiles of antimalarials, i.e., chloroquine (CQ), quinine (QN), mefloquine (MQ), and artesunate (ARS) in Plasmodium falciparum isolates collected during the period from 1988 to 2003 were studied. P. falciparum isolates from infected patients were collected from the Thai-Cambodian border area at different time periods (1988-1989, 1991-1992, and 2003), during which 3 different patterns of drug use had been implemented: MQ+sulphadoxine (S)+pyrimethamine (P), MQ alone and MQ+ARS, respectively. The in vitro drug susceptibilities were investigated using a method based on the incorporation of $[^3H]$ hypoxanthine. A total of 50 isolates were tested for susceptibilities to CQ, QN, MQ, and ARS. Of these isolates, 19, 16, and 15 were adapted during the periods 1988-1989, 1991-1993, and 2003, respectively. P. falciparum isolates collected during the 3 periods were resistant to CQ. Sensitivities to MQ declined from 1988 to 2003. In contrast, the parasite was sensitive to QN, and similar sensitivity profile patterns were observed during the 3 time periods. There was a significantly positive but weak correlation between the $IC_{50}$ values of CQ and QN, as well as between the $IC_{50}$, values of QN and MQ. Drug pressure has impact on sensitivity of P. falciparum to MQ. A combination therapy of MQ and ARS is being applied to reduce the parasite resistance, and also increasing the efficacy of the drug.

• Journal of Microbiology
• /
• v.42 no.2
• /
• pp.80-86
• /
• 2004

Pulsed-field gel electrophoresis (PFGE) typing was applied to the epidemiological investigation of 21 Candida tropicalis isolates collected from urine specimens of 11 patients and one healthcare worker, in an intensive care unit (ICU) over a 4-month period. Seventeen epidemiologically unrelated strains from 14 patients were also tested to determine the discriminatory power of PFGE. PFGE typing consisted of electrophoretic karyotyping (EK) and restriction endonuclease analysis of genomic DNA (REAG), using two restriction enzymes (BssHII and SfiI). The EK pattern was the same in all 38 isolates, while REAG using SfiI separated the isolates into nine types. However, 16 different PFGE types were iden-tified by REAG with BssHII, and the same results were obtained when the results of both REAG tests were combined. In serial urinary isolates from 10 patients, all strains from each patient had the same PFGE pattern. While the epidemiologically unrelated strains from 14 patients consisted of 13 different PFGE types, the 20 isolates from the 11 ICU patients fell into only two PFGE types (types Cl and C2), and these apparently originated from the two different outbreaks. All strains of type Cl (n = 12) were isolated from six patients, between November 1999 and January 2000, and all of the type C2 strains (n=8) were isolated from five patients, during January and February 2000. This study shows two con-secutive clusters of C. tropicalis candiduria in an ICU, defined by PFGE typing, and also demonstrates that a PFGE typing method using BssHII is perhaps the most useful method for investigating C. tropi-calis candiduria.

• The Korean Journal of Mycology
• /
• v.21 no.4
• /
• pp.293-300
• /
• 1993

For the enzymes AAT, GmDH, ME, GPI, LDH and IDH, nine, seven, four, nine, seven, and four different phenotypes, respectively, were observed. All six isolates of an unidentified sterile Pythium sp. isolated from field soil showed the same band positions for all six enzymes compared. These phenotypes were not similar to any of the known Pythium species. Two isolates of unknown Pythium species (145 and 299) showed the same band positions for all six enzymes. The phenotypes for all three unknown Pythium spp. were different from the other species in the experiment. Five isolates of P. heterothallicum showed the same band positions for all enzymes compared except one enzyme, lDH. Two isolates of P. torulosum showed the same band petitions for enzymes AAT, GmDH and ME, and three isolates of P. totulosum showed the same positions for enzymes GPI, LDH, and IDH. Single isolates of P. spinosum and P. irregulare showed the same band positions for enzymes AAT, GmDH and GPI. In conclusion, sterile types of Pythium species showed 100% similarities among themselves but did not show any similarity with all isolates of P. heterothallicum and P. spinosum isolate, and showed very low similarities with other isolates in general except with unknown Pythium isolate 306. Similarity levels between different species were low in general with few exceptions.

• Korean Journal of Breeding Science
• /
• v.40 no.4
• /
• pp.394-400
• /
• 2008

Blast resistance of one hundred and thirty-one rice cultivars bred in Korea was tested with thirty Korean isolates and twenty-two Philippines isolates using three screening methods. In the blast nursery conducted in Korea and in the Philippines, average disease index of rice cultivars were 4.6 and 2.2, respectively. Seventy-nine cultivars showed different resistance reaction in Korea and in the Philippines, and 19 cultivars showed the same resistant reaction in two locations. In the seedling test, Korean blast isolates displayed different levels of virulence. 93-093, a Korean isolate, was compatible with 90 cultivars whereas 97-057 showed a compatible reaction with 13 cultivars. Twenty-three cultivars showed high level of resistance against Korean and Philippines isolates but Chucheongbyeo, Heugnambyeo, and Manmibyeo showed susceptible reaction to all blast isolates. Through the sequential planting test in Korea and in the Philippines, Palgongbyeo and Seomjinbyeo displayed durable resistance, and Nagdongbyeo and Gihobyeo showed high level of disease infection over the planting time. These results indicate that blast isolates collected in two countries have different genetic background and number of compatible isolates should be considered in definition the durability of rice cultivar to rice blast.