• The Korean Journal of Zoology
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• v.33 no.1
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• pp.6-11
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• 1990

Analysis of genetic structure in Kimpo natural population of Drosophila was carried out by utilizing the deleterious gene on the second chromosome of Drosophila melanogaster. Male flies tested were continuously collected for eight years; in late September 1974 and 1981-1987. The frequency of deleterious gene (lethal plus semilethal) ranged from 27.02% in 1983 to 41.48% in 1987, and the values estimated from the eight years samples are highly signihcent from each other with a homogenety test (X$^2$=52.0157, d.f.=28, P<0.005). Allelic rates ranged from 1.30% in 1981 to 5.03% in 1974. And the effective population size by using the rate of allelism was estimated average at 3, 300 pairs. Elimination rate by homozygous of lethal gene ranged from 0.0004 in 1984 to 0.0019 in 1974, and that is for smaller than mutation rate(0.005) at second chromosome. We suppose that stable frequency (about 20%) lethal genes of D. melanogaster in Kimpo natual population are maintained by invade of P-type mutator factor (P element) versus eliminated in heterozygous and homozygous condition of lethal gene.

• The Korean Journal of Zoology
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• v.19 no.1
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• pp.15-24
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• 1976

The frequency of the second chromosomes bearing deleterious genes in the Anyang natural population of Korea in Drosophila melanogaster was repeatedly estimated during the period from 1971 through 1973. 1) The frequency of lethal and semilethal chromosomes was calculated to be 28.2%, and the frequencies were maintained without fluctuation for three years. 2) Allelism rate between lethal genes isolanted from each year was 0.77% on the average. The rate of elimination of lethal genes $(IQ^2)$ was estimated to be 0.0008. 3) The frequency of sterile gene on the second chromosomes was estimated to be 9.1% for females, 6.8% for males and 2.0% for both sexes, respectively. 4) Recessive visible mutant genes, namely rbl and bw genes, were frequently extracted when the chromosomes were revealed in homozygous. The frequencies of these mutants were found to be 1.3% for bw genes and 2.7% for rbl genes, respectively.

• Journal of the Korea Institute of Military Science and Technology
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• v.24 no.3
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• pp.348-355
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• 2021

Hantaan virus(HTNV) causes hemorrhagic fever with renal syndrome(HFRS) with a case fatality rate ranging from <1 to 15 % in human. Hantavax^Ⓡ is a vaccine against the Hantavirus, which has been conditionally approved by the Ministry of Food and Drug Safety(MFDS). However, only 50 % of volunteers had neutralizing antibodies 1 year following the boost. Effective antiviral treatments against HTNV infection are limited. Hantaviruses generally cause asymptomatic infection in adult mice. On the other hand, infection of suckling and newborn mice with hantaviruses causes lethal neurological diesease or persistant infection, which is different from the disease in humans. The development of vaccines and antiviral strategies for HTNV has been partly hampered by the lack of an efficient lethal mouse model to evaluate the efficacy of the candidate vaccines or antivirals. In this report, we established a lethal mouse model for HTNV, which may facilitate in vivo studies on the evaluation of candidate drugs against HTNV. The median lethal dose value of HTNV was calculated by probit analysis of deaths occurring within two weeks. Five groups of ten ICR mice were injected intracranially with serial 2-fold dilutions (from 50 to 3.125 PFU/head) of HTNV. Mice injected with HTNV began to die at 8 days post-infection. The lethal dose required to kill 50 % of the mice (LD₅₀) was calculated to be 2.365 PFU/head.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.38 no.2
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• pp.100-105
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• 2005

Two species of fish and five species of marine invertebrate showed different tolerances to the toxicity of composite slag and bituminaus coal. Especially, Hemicentrotus pulcherrimus and young Haliotis discus hannai displayed marked differences in tolerance from. H. pulcherrimus and young H. discus hannai showed lethal effects at higher concentrations than those concentrations of the composite slag in the 1.0 and $0.4\%$ range, respectively. H. pulcherrimus showed no lethal effects at a lower concentration of $1.0\%$ composite slag and some differences in the rate of oxygen consumption with this concentration of composite slag. The lethal effects of bituminous coal on marine and fisheries organisms, even with higher concentrations, were not observed. At a higher concentration than that of 500 mg/L (ppm) of bituminous coal, decrease effects appeared in the rate of oxygen consumption of the experimental organisms. Taking into consideration that the experimental concentration of composite slag and bituminous coal were impracticable in the ocean, the results of this experiment suggest that composite slag and bituminous coal pose no real threat to marine or fisheries organisms.

• Fisheries and Aquatic Sciences
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• v.8 no.3
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• pp.161-166
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• 2005

We examined the variation in survival and the respiration and filtration rates of Tresus keenae in response to changes in water temperature and salinity. The survivorship of animals exposed to temperatures below $25^{\circ}C$ for 7 days was $80\%$; however, all test animals died on the fourth day at $28^{\circ}C$. The upper lethal temperature over 7 days was $25.9^{\circ}C$. After exposure to lower temperatures, $93\%$ ofthe animals survived at temperatures over $5^{\circ}C$ for 10 days. Survivorship rapidly decreased below $4^{\circ}C$ with all test animals dying at $2^{\circ}C$ on the eighth day. The $LT_{50}$ over 10 days was $4.8^{\circ}C$. The respiration and filtration rates of T. keenae increased as temperature increased. It is believed that energy consumption increases as a result of the increased respiration rate at temperatures above the upper lethal temperature. At temperatures below the lower lethal temperature, the metabolic rate of T. keenae was substantially lowered. In response to changes in salinity, the survivorship of T. keenae was $90\%$ at 30.2 psu after exposure for 5 days; at below 26.8 psu, all test animals died by the fifth day. The $LS_{50}$ was 29.1 psu. As salinity decreased, both the respiration rate and the filtration rate decreased. At 23.5 psu, the respiration and filtration rates decreased by 48 and $34\%$, respectively. These data have implications for increasing efficiency in the production and management of shellfish aquaculture farms.

• Journal of the Korean Society for Marine Environment & Energy
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• v.9 no.4
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• pp.187-192
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• 2006

In order to know the biological effect of effluent from shipyard and the adjacent stream water on four organisms (flatfish, rockfish, sea squirt and arkshell) cultured around the shipyard, lethal rate and DNA damage were measured after 48 hr exposure and carried out by a single cell gel electrophoresis, namely comet assay. $LC_{50}$ (48 hr) could not be calculated in any organism 48 hours after exposure to effluent from shipyard and stream water, because all organism showed a lethal rate lower than 20%. Regardless of no acute toxicity, DNA damage of flatfish and rockfish was detected higher in Jang-Pyoung stream than in control, whereas sea squirt revealed higher DNA damage in laundry waste water. From these results, Jang-Pyoung stream seemed to have a relatively higher genotoxicity rather than effluent from shipyard.

• 한국해양학회지
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• v.13 no.1
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• pp.35-43
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• 1978

Short-term acute toxicity of mercury, cadmium and copper to arkshell, Anadara broughtonii, and to oyster, Crassostrea gigas, was determinedby static bioassays from 20 May to 27 June in 1977. During the observations of the opening rate of the shell mercury was the most sensitive toxicant of the three toxic substances to the test animals and caused them to close their shellvalves together after being exposed to a mercury solution for an hour during the test. Opening rate to cadmium and copper increased gradually at the higher concentration. the 96hr-LC50 values for the test animals are 4.84mg/l for mercury and 1.86mg/l for cadmium, while the 72hr-LC50 value for copper is 0.31mg/l. the death rate of oysters for cadmium showed lower than that of the mercury and copper test solutions. The 96hr-LC50 values of mercury, copper and cadmium were 1.1mg/l, 2.54mg/l and 19.5mg/l, respectively. For oysters mercury was the most toxic substance, and cadmium was the least toxic one. the medium lethal time (LT 50) value decreased gradually at higher concentration of heavy metals. The LT 50 of 2mg/l was found within 96 hours ofr copper, 104 hours for mercury and 121 hours for cadmium. The lethal threshold concentrations for 7 days were found to be about 1mg/l for mercury and copper, and 2mg/l for cadmium.

• Horticultural Science & Technology
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• v.34 no.1
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• pp.122-133
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• 2016

While ion beams are widely used in plant breeding, little is known about the sensitivity of Lavandula angustifolia (lavender) to ionizing radiation. To compare the biological effects of different types of ionizing radiation on the germination and survival rates of lavender, we exposed lavender seeds to gamma rays, 3 MeV electron beams, and 1.89 MeV proton ion beams. We observed that the seed germination rate decreased with increasing dosages of all three types of ionizing radiation. The malformation rate of lavender seedlings exposed to electron beams and gamma rays increased with increasing radiation dosage. By contrast, the effect of the accelerated proton beams on the malformation rate was negatively correlated with the dosage used. The survival rate of lavender seedlings exposed to the three types of ionizing radiation decreased in a dose-dependent manner. In addition, the survival rate of seedlings irradiated with proton and electron beams decreased more slowly than did that of seedlings irradiated with gamma rays. The half-lethal dose of gamma rays, electron beams, and proton beams was determined to be 48.1 Gy, 134.3 Gy, and 277.8 Gy, respectively, and the most suitable proton-ion energy for lavender seeds in terms of penetration depth was determined to be 5 MeV. These findings provide valuable information for the breeding of lavender by radiation mutation.

• Horticultural Science & Technology
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• v.32 no.2
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• pp.241-251
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• 2014

This study was carried out to develop a simple, rapid and reliable assessment model to predict cold tolerance in Pittosporum tobira, a broad-leaved evergreen commonly used in the southern region of South Korea, which can minimize the possible experimental errors appeared in a electrolyte leakage test for cold tolerance assessment. The modeling procedure comprised of regrowth test and a electrolyte leakage test on the plants exposed to low temperature treatments. The lethal temperatures estimated from the methodological combinations of a electrolyte leakage test including tissue sampling, temperature treatment for potential electrical conductivity, and statistical analysis were compared to the results of the regrowth test. The highest temperature showing the survival rate lower than 50% obtained from the regrowth test was $-10^{\circ}C$ and the lethal was $-10^{\circ}C{\sim}-5^{\circ}C$. Based on the results of the regrowth test, several methodological combinations of electrolyte leakage tests were evaluated and the electrolyte leakage lethal temperatures estimated using leaf sample tissue and freeze-killing method were closest to the regrowth lethal temperature. Evaluating statistical analysis models, linear interpolation had a higher tendency to overestimate the cold tolerance than non-linear regression. Consequently, the optimal model for cold tolerance assessment of P. tobira is composed of evaluating electrolyte leakage from leaf sample tissue applying freeze-killing method for potential electrical conductivity and predicting lethal temperature through non-linear regression analysis.

• Korean Journal of Environmental Biology
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• v.23 no.4
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• pp.390-397
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• 2005

The inhibition of cell recovery might be proceeded via either the damage of the mechanism of the recovery itself or via the formation of irreversible damage which could not be repaired at all. Both these processes may take place at the same time. Any of these possibilities would result in a decrease in both the rate and extent of cell recovery. To distinguish them, a quantitative approach describing the process of recovery as a decrease in the effective radiation dose was applied to experimental data on the recovery from potentially lethal damage in Chinese hamster cells exposed to X-rays alone or combined with various chemicals (pyruvate, novobiocin, lactate, nalidixic acid, 3-aminobenzamide). For these particular cases, it is concluded that the recovery process itself is not damaged and the inhibition of the recovery is entirely due to the enhanced yield of the irreversibly damaged cells.