• Journal of Marine Life Science
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• v.7 no.2
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• pp.113-120
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• 2022

Despite concerns about the significant toxicity of copper pyrithione (CuPT) at environmental concentrations, effects of CuPT on benthic organisms have received little attention. Here, we analyzed the detrimental effects of CuPT at sublethal concentrations (1/50, 1/20, and 1/10 of the 96 h-LC50 value) for 14 days in the marine polychaete Perinereis aibuhitensis. Reduced burrowing activity and significantly decreased the acetylcholinesterase activity in response to relatively high concentrations of CuPT were identified as CuPT-triggered cholinergic inhibition. The lipid peroxidation marker, malondialdehyde levels were dose-dependently increased, whereas intracellular glutathione was depleted by relatively high concentrations. In the CuPT-treated polychaete, significant fluctuations in the enzymatic activities of the antioxidant defense system (catalase, superoxide dismutase, glutathione reductase, and glutathione peroxidase) were observed with significantly modulated glutathione 𝘚-transferase activity. These results indicate that even sublethal levels of CuPT would have detrimental effects on the health status of the marine polychaete.

• Korean Journal of Microbiology
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• v.29 no.1
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• pp.49-55
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• 1991

The heat shock responses of Campylobacter jejuni were studied by examination of their survival rates and synthesis of heat shocd proteins. When C. jejuni cells were treated at the sublethal temperatures of 48.deg.C for 30 minutes, most of the cells maintained their viabilities and synthesized the heat shock proteins of 90, 73, and 66 kD in molecular weight. By the method of two-dimensional electrophoresis, the heat shock proteins of C. jejuni were identified to be Hsp90, Hsp73, and Hsp66. During the heat shock at 48.deg.C, the heat shock proteins were induced from about 5 minutes after the heat shock treatment. Their synthesis was continued upto 30 minutes, but remarkably retarded after 50 minutes. When C. jejune cells were heat shocked at 51.deg.C for 30 minutes, the survival rates of the cells were decreased by about $10^{3}$ fold and synthesis of heat shock proteins and normal proteins was also generally retarded. The cells exposed to 55.deg.C for 30 minutes died off by more than $10^{5}$ cells and the new protein synthesis was not observed. But when C. jejuni cells were heat-shocked at the sublethal temperature of 48.deg.C for 15 to 20 minutes and then were exposed at the lethal temperature of 55.deg.C for 30 minutes, their viabilities were higher than those exposed at 55.deg.C for 30 minutes without pre-heat shock at 48.deg.C. Therefore, the heat shock proteins synthesized at the sublethal temperature of 48.deg.C in C. jejuni were thought to be responsible for thermotolerance. However, when C. jejuni cells heat-shocked at various ranges of sublethal and lethal temperatures were placed back to the optimum temperature of 42.deg.C, the multiplication patterns of the cells pretreated at different temperatures were not much different each other.

• Journal of the Korean Society of Radiology
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• v.9 no.6
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• pp.417-420
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• 2015

We obtained Surviving Fraction (SF) after irradiation carbon beam to compare the applicability of the Linear-Quadratic model, Incomplete Repair model, Marchese model. Mathematica software(ver 9.0) used to calcurate parameters and compared result. LQ model could not explain the entire response of fractionated carbon beam irradiation. It becomes necessary to construct models that extend the LQ model of conventional radiotherapy for the carbon beam therapy. By combining both Potentially Lethal Damage Repair (PLDR) and Sublethal Damage Repair (SLDR) a new LQ model can develop that aptly modeled the cellular response to fractionated irradiation.

• Journal of Microbiology and Biotechnology
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• v.21 no.4
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• pp.438-447
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• 2011

Deinococcus radiodurans is extremely resistant to various genotoxic conditions and chemicals. In this study, we characterized the effect of a sublethal concentration (100 ${\mu}M$) of cadmium (Cd) on D. radiodurans using a whole-genome DNA microarray. Time-course global gene expression profiling showed that 1,505 genes out of 3,116 total ORFs were differentially expressed more than 2-fold in response to Cd treatment for at least one timepoint. The majority of the upregulated genes are related to iron uptake, cysteine biosynthesis, protein disulfide stress, and various types of DNA repair systems. The enhanced upregulation of genes involved in cysteine biosynthesis and disulfide stress indicate that Cd has a high affinity for sulfur compounds. Provocation of iron deficiency and growth resumption of Cd-treated cells by iron supplementation also indicates that CdS forms in iron-sulfur-containing proteins such as the [Fe-S] cluster. Induction of base excision, mismatch, and recombinational repair systems indicates that various types of DNA damage, especially base excision, were enhanced by Cd. Exposure to sublethal Cd stress reduces the growth rate, and many of the downregulated genes are related to cell growth, including biosynthesis of cell membrane, translation, and transcription. The differential expression of 52 regulatory genes suggests a dynamic operation of complex regulatory networks by Cd-induced stress. These results demonstrate the effect of Cd exposure on D. radiodurans and how the related genes are expressed by this stress.

• Ocean and Polar Research
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• v.28 no.1
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• pp.45-56
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• 2006

This study investigated primarily the toxic effects of bis(tributyltin)oxide (TBT) and DDT (Dichlorodiphenyltrichloroethane) on the mortality of adult Acartia omorii and barnacle nauplii as well as the hatching rate of A. omorii. Subsequently, compound effects of TBT and DDT on the mortality of immature copepods were tested in order to assess whether or not synergistic influence existed in the mixture of sublethal concentration of two pollutants. Mortality of adult A. omorii increased as exposure concentration of DDT increased in the range of from 0.0001 to 1ppm. Egg hatching rate of the copepod showed no distinctive difference in the range between 0.1 and 10ppm, while barnacle nauplii showed abnormal motility of their appendages in the range of 0.0001 to 1 ppm. Mortality of adult A. omorii increased as TBT concentration increased within the range of 1 and 10 ppb, whereas egg hatching rate of the copepod showed no linear response to the same exposure range. Moreover, copepod nauplii were almost motionless even though copepod eggs hatched under the exposure condition of TBT $(0{\sim}10 ppb)$ and DDT $(0{\sim}10 ppm)$, respectively, suggesting that the nauplii are hard to develop into adult stage. On the basis of the sublethal concentration less than the 24-h $LC_{50}$, 0.001 ppm (DDT) and 2 ppb (TBT) were selected to confirm the compound effects of two pollutants on the mortality of immature copepods. Mortality of immature copepods under the condition of mixture of the two pollutants was higher than that in the single exposure condition. This result seems to indicate that synergistic effects of sublethal toxicants can make a more hazardous effect on the survival of immature copepods even though the concentration of single toxicant is not lethal to copepods in the marine environment.

• Korean journal of applied entomology
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• v.36 no.3
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• pp.249-255
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• 1997

The sublethal temperature (5$^{\circ}$C for 2hr) led the fifth instar larvae of beet armyworm, Spodoprern exigucr (Hiibner), to increase cold tolerance to subzero lethal temperatures ( 'rapid cold hardening' ). The strength of rapid cold hardening was, however, varied among different populations which showed different cold tolerance in response to cold temperatures. To analyse the physiological factors affecting the rapid cold hardening, hernolymph osmolalities. supercooling points, glycerol contents, and cold stress proteins were measured by treating the fifth instar larvae with the sublethal low temperatures. The treated larvae showed increase of hemolymph osmolalities and glycerol contents. Changes of the osmolalities were greater in cold-hardy strains than in cold-susceptible strains. The sublethal temperature also induced them to express the cold-stress proteins (I0 - 20kD) in the hemolymph. but did not to change supercooling points.

• Proceedings of the Zoological Society Korea Conference
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• 2000.10a
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• pp.159.2-160
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• 2000

No Abstract, See Full Text

• Proceedings of the PSK Conference
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• 2002.10a
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• pp.309.1-309.1
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• 2002

Ginsan, a polysaccharide extracted from Panax ginseng. was earlier scrutinized for a biological-response modifier. We further studied the protective and restorative activity of Ginsan against sublethal dose irradiation owing to increase production of endogenous hematopoietic growth factors such as IL-1. TNF-${\alpha}$. IL-6, GM-CSF. Which induce strong redox-emzyme elevation. Exposing to radiation induces reactive oxygen species (ROS). which play an important causative role in radiation damage. (omitted)

• Fisheries and Aquatic Sciences
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• v.13 no.2
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• pp.112-117
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• 2010

Altered mRNA expression of two metallothionein isoforms (MT-IA and MT-IB) in response to acute heavy metal exposure was examined in mud loach, Misgurnus mizolepis, fry using a real-time RTPCR assay. Sublethal exposure (1 or 5 ${\mu}M$) to Cd, Cr, Fe, Mn, Ni, and Zn resulted in highly variable transcriptional responses of the two MT isoforms to the heavy metal ions, including upregulation, a steady state, and downregulation. Overall, the most potent inducer of both MT isoforms was Cd (up to 6-fold). Another exposure experiment using a series of doses of Cu revealed that the stimulation patterns of the two MT isoforms differed: MT-IA transcription was soon saturated at higher concentrations (about 2-fold at 1-4 ${\mu}M$ of Cu), whereas the activation of MT-IB was more dependent on the treatment dose (increased up to 5-fold at 3 ${\mu}M$). The isoform-specific allotment of constitutive and inducible functions was not as clear in fry as in adult tissues. Coordinated interaction between the MT-IA and MT-IB isoforms was hypothesized based on the finding that MT-IA represented a primary action under 'less stressful' or 'sublethal' conditions, whereas the activation of MT-IB became important under 'more stressful' or 'lethal' circumstances in this species.

• Radiation Oncology Journal
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• v.3 no.1
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• pp.1-8
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• 1985

To determine the dose·survival and repair characteristics of the jejunal crypt cells, experimental study was carried out using total 70 mice. Single or split irradiations of 1,100 to 2,200 rad were delivered to whole bodies of $C_{57}$ BL mice, using a cesium 137 animal irradiator and those mice were sacrificed after 90 hours. The number of regenerating crypts per jejunal circumference was counted by a jejunal crypt cell assay technique and dose·response curve was measured. The results were as follows : 1. The average number of jejunal crypts per circumference in control group was 140. In a single irradiation group, the number of regenerated jejunal crypts was, 125, 56, 2 in each subgroup of 1,100 rad, 1,400 rad and 1,800 rad respectively. In split irraiation group, it was 105,44,2 in each subgroup of 1,400rad 1,800rad and 2,200rad respectively. 2. Mean lethal dose of mouse jejunal crypt cell was 167 and 169 rad respectively in a single and split irradiation. 3. Repair dose of sublethal damage was 280 rad. 4. Sublethal damage was completely repaired within 4 hours between the split dose of irradiation.