• Korean Journal of Ichthyology
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• v.23 no.1
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• pp.61-69
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• 2011

Gene and promoter structures of metallothionein(MT) from Miho spine loach (Cobitis choii; Cypriniformes) were characterized, and the transcriptional responses to experimental exposures to heavy metals and heat stress were examined. The C. choii metallothionein displayed well-conserved features of teleostean metallothioneins at gDNA, mRNA and amino acid levels. Bioinformatic analysis predicted that the C. choii MT regulatory region potentially possessed various motifs or elements targeted by various transcription factors associated with metal-coordinating regulation (e.g., metal transcription factor-1), immune responses (e.g., nuclear factor kappa B), and thermal modulations (e.g., heat shock factor). Acute heavy-metal exposures to 0.5 or $1.0\;{\mu}M$ of cadmium (Cd), copper (Cu), manganese (Mn), nickel (Ni) or zinc (Zn) showed that MT transcription was significantly stimulated by Cd (9.6-fold relative to non-exposed control) and Cu (10.4-fold), only moderately by Mn (2.4-fold), but hardly by Ni and Zn. Elevation of water temperature from $25^{\circ}C$ to $31^{\circ}C$ caused a rapid modulation of MT mRNAs toward upregulation to 9.5-fold; however, afterward the elevated mRNA level slightly decreased during further incubation at $31^{\circ}C$ for 6 h. Results from this study suggest that MT-based expression assay could be a useful basis for better understanding the metal- and/or heat-caused stresses in this endangered fish species.

• Tuberculosis and Respiratory Diseases
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• v.50 no.5
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• pp.579-590
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• 2001

Background : The aging process may be induced, at least in part, by reactive oxygen species(ROS). It has been thought that the lung could be a good source of ROS because it has a high oxygen tension. In the present study, we invetigated the inducibility of the first and last lines against oxidative stress, superoxide dismutases(CujZn-SOD and Mn-SOD) as a scavenger of ${O_2}^-\;{\cdot}$ and metallothionein(MT) as a scavenger of $OH{\cdot}$, respectively, in mouse lungs with age. Methods : Oxidative stress was induced by paraquat, an intracellular superoxide generator, at 1, 4, 8, and 12 months of age and then SODs and MT mRNAs were determined by RT-PCR method. Results : The steady-state level of Mn-SOD mRNA increased from 1 to 8 months but decreased thereafter. However, Mn-SOD mRNA was not induced by paraquat after 1 month. On the other hand, there was no change in the steady-state level of Cu/Zn-SOD mRNA, which decreased abruptly at 12 months of age. Additionally, Cu/Zn-SOD mRNA was not induced by paraquat at any age. There was no change in the steady-state level of MT mRNA with age whereas its inducibility by paraquat was intact at all ages. Conclusion : These results indicate that lack of induction of SODs with age may be one of the causative factors in the aging process while induction of MT may play an important role in the defense against oxidative stress. It is therefore implicated that the tissue antioxidant/prooxidant balance could be one of determinants of mean life span.

• Journal of Environmental Health Sciences
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• v.24 no.2
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• pp.47-56
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• 1998

When rats are exposed to cadmium in their diet, the cadmium accumulates in the liver. This study was carried out to investigate the effect of chitin, chitosan and dithiocarbamate chitosan on the cadmium accumulation in liver of rats. For this experiment, 10 male Sprague-Dawley were used. The experimental groups were divided into four independent groups which were one control group and three experimental groups by cadmium alone treatment or chitin, chitosan and dithiocarbamate chitosan with cadmium. In order to investigate the eliminative effect of chitin, chitosan and dithiocarbamate chitosan on the cadmium accumulation in liver of rats, the cadmium concentration, the metallothionein level and the enzyme activitys were measured. The results obtained revealed the eliminative effect of cadmium in liver of rats by chitin, chitosan and dithiocarbamate chitosan. The effect of chitin on the cadmium elimination was less than that of chitosan and dithiocarbamate chitosan. Also it shows that the eliminative effect of cadmium by dithiocarbamate chitosan was the highest.

• Bulletin of Food Technology
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• v.23 no.2
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• pp.205-211
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• 2010

• Korean Journal of Ichthyology
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• v.23 no.1
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• pp.10-20
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• 2011

Genetic determinant for metallothionein (MT), a cysteine-rich protein playing essential roles in metal detoxification and homeostasis, was characterized in the Korean bitterling (Acheilognathus signifer, Cyprinidae), an endemic fish species. The full-length A. signifer MT (AsMT) cDNA (551 bp) is composed of a single open-reading frame (ORF) to encode a polypeptide of 60 amino acids containing 20 cysteine residues whose positions are conserved in most cypriniform MTs. At the genomic level, the AsMT (2,593 bp spanning the 5'-flanking region to the 3'-untranslated region) represented a conserved tripartite (three exons interrupted by two introns) structure with AT-rich introns. The upstream regulatory region (-1,914 bp from the ATG initiation codon) of AsMT displayed various sites and motifs for transcription factors involved in the metal-mediated regulation and stress/immune responses. The AsMT transcript was ubiquitously detected in various organs with variable expression levels, where the ovary and intestine showed the highest expression, while the heart and skeletal muscle represented the lowest level. During an exposure to copper (immersion in $0.5\;{\mu}M$ Cu for 48 h), the levels of AsMT transcripts were significantly elevated in the liver (more than 3.5-fold), moderately in the gill, kidney, and spleen (ranging from 1.5- to 2.5-fold), and barely in the brain and intestine. Results of this study could form a useful basis to explore the metal-related stress physiology of this endangered fish species.

• Journal of environmental and Sanitary engineering
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• v.21 no.1 s.59
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• pp.52-57
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• 2006

Metallothioneins(MTs) belong to the class of low molecular weight proteins. Recently, it has been suggested that MTs may playa direct role in cellular defense against oxidative stress by functioning as antioxidants. Oxidative damage to different cellular components makes a major contribution to many pathogenenesses. Several studies have demonstrated that MT is able to quench a wide range of reactive oxygen species at a higher efficiency than other well known antioxidants such as superoxide dismutate(SOD). The present study was designed to evaluate the effect of MT on the activities of the reactive oxygen species removal system. MT showed the scavenging of superoxide in the SOD assay system in the presence or absence of SOD. When MT was added to nicotinamide adenine dinucleotide phosphate(NADPH) oxidation system in presence of fixed amount of SOD increase the breakdown rate of superoxide. When MT was added to the system that form nitrite from hydroxylammonium chloride, the formation of nitrite was inhibit. We concluded that the function of MT as antioxidant might have an effect on the level of superoxide scavenging.

• Journal of Environmental Health Sciences
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• v.24 no.3
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• pp.107-113
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• 1998

This study was performed to investigate the effects of chitin, chitosan and dithiocarbamate chitosan on the cadmium accumulation in liver and kidney of catfish. The experimental groups were divided into four independent groups which were one control group and three experimental groups by cadmium alone treatment or chitin, chitosan and dithiocarbamate chitosan which cadmium. in order to investigate the effects of chitin, chitosan and dithiocarbamate chitosan on the cadmium accumulation in liver and kidney of catfish, the cadmium concentration, the metallothionein level were measured. The results obtained were as follows: 1. The cadmium concentrations in liver and kidney of catfish in cadmium alone treatment group were similar to that of the chitin treatment group, but chitosan and dithiocarbamate chitosan treatment groups were significantly decreased. 2. The metallothionein levels in liver and kidney of catfish alone treatment group were similar to that of the chitin treatment group, but chitosan and dithiocarbamate chitosan treatment groups were significantly increased. In conclusion, this study revealed the effect of chitin, chitosan and dithiocarbamate chitosan against cadmium accumulation in liver and kidney of catfish. It exhibited the highest effect at dithiocarbamate chitosan treatment group.

• Korean Journal of Ecology and Environment
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• v.40 no.4
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• pp.489-494
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• 2007

Transcriptional modulation of metallothionein (MT) during acute metal exposures (cadmium, copper or zinc) was examined in fry of Hemibarbus mylodon, a threatened fish species in Korean peninsula. Viability of H. mylodon fry was most affected by copper exposure (up to 79% of mortality at 1 ppm for 48 hours) and considerably by cadmium exposure (21 to 54% of mortality). On the other hand, Zn showed the least adverse effect on the viability (0 to 13% of mortality) of this species. Based on the semi-quantitative RT-PCR analysis, the stimulation of MT mRNA in response to metal exposures followed generally in a dose-dependent fashion where cadmium was the most potent inducer for the induction of MT transcripts in fry (up to more than 5-fold) while the lowest response was observed in zinc-exposed group (2-fold at maximum). From the exposure using environmentally realistic doses of cadmium (0 to 0.05 ppm for 24 hours), MT expression at mRNA level was also sensitively modulated toward upregulation up to more than 3-fold as relative to non-exposed control. Results from the present study would be a good basis for understanding the adaptive capacity and stress physiology of this endangered fish species during metal pollution.

• Environmental Analysis Health and Toxicology
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• v.19 no.2
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• pp.191-200
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• 2004

Zinc (Zn) is an essential element in biological process, however inadequate Zn status in general population have been recognized. To update the knowledge for Zn-cadmium (Cd) interaction, we studied the intestinal uptake and transport, and the expression of metal transporter proteins (divalent metal transporter 1, DMT1 ; metal transporter protein 1, MTP1 ; zinc transporter 1, ZnTl ; metallothionein 1 , MT1) in duodenum after Cd exposure using Zn deficient animal model. Rats were led Zn deficient (ZnD, 0.5-1.0 mgZn/kg) or Zn supplemented (ZnS, 50mg Zn/kg) diet for 4 weeks, and followed single administration of $^{109}$ CdCl$_2$orally. The body Zn flatus and tissue Cd concentration were determined at 24 hrs after Cd administration. Total body burden of Cd and Cd absorption index (AI, %) were estimated based on the tissue Cd analyzed. DMT1, MTP1, ZnTl and MT1 mRNA were analyzed by using RT-PCR method. Feeding of Zn deficient diet for 4 weeks produced a reduced body weight gain and a depletion of body Zn. Tissue Cd concentration, body burden of Cd and Cd absorption index were higher in the ZnD diet fed rats than the ZnS diet red rats. Especially, Cd concentration in the small intestine (duodenum, jejunum and ileum) and the colon of FeD diet fed rats were higher markedly than in the FeS diet group. The expression levels of DMT1, MTP1 and ZnT1 mRNA in FeD diet fed rats were similar to the FeS diet. The level of MT1 mRNA expression was significantly lower in the FeD than the FeS diet fed rats. Taken together, theses results indicate that Zn deficiency in diet induce an increased intestinal absorption and tissue retention of Cd, and down -regulate the MT1 expression in the intestine which might be play a part of role in Cd absorption and transport in mammalian. These findings suggest that deficiency of essential metal could be enhanced the toxicity of toxic, non-esstial metals through the metal-metal interaction.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.44 no.2
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• pp.126-140
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• 2011

Genetic determinants of two metallothionein isoforms (MT-A and MT-B) were isolated and characterized from the perciform species, rockbream (Oplegnathus fasciatus). Rockbream MT-A and MT-B shared a high degree of homology at amino acid levels with representative orthologs from other perciform species, especially with respect to the conserved cysteine residues. At the genomic level, both MT-A and MT-B genes represent a tripartite structure typical of vertebrate MT genes. However, rockbream MT-B showed unusually large introns (1.2 kb and 0.8 kb for intron I and II, respectively), a phenomenon that has rarely been seen in other vertebrate MT genes. MT-A and MT-B transcripts were ubiquitously detected in a wide array of tissues, wherein brain and eye showed the highest basal expression levels, and the fin exhibited the lowest expression of both isoforms. The basal expression of MT-A in most tissues was significantly higher (ranging from 4- to 10-fold) than that of MT-B. Upon heavy metal exposures to Cd, Cu or Zn at 25 ppb for 48 h, MT-A and MT-B transcripts in the liver were significantly activated by Cd and moderately by Zn. On the other hand, exposure to Cu did not result in alterations of MT-A, nor in the significant suppression of MT-B. Following bacterial challenges with Escherichia coli, Edwardsiella tarda or Streptococcus iniae, MT isoforms in the liver, kidney and spleen were highly modulated and exhibited a pattern that was dependent on the bacterial species, tissues and isoforms. These results suggest that the two MT isoforms could be taken into account as potential indicators of metal toxicity and immune perturbations of this aquaculture-relevant species.