메뉴 건너뛰기




Volumn 228, Issue 1, 2006, Pages 77-84

Effects of perinatal exposure to low doses of cadmium or methylmercury on thyroid hormone metabolism in metallothionein-deficient mouse neonates

Author keywords

Brain development; Cadmium; Iodothyronine deiodinase; Metallothionein; Methylmercury; Thyroid hormone

Indexed keywords

BRAIN ENZYME; CADMIUM; LIVER ENZYME; METALLOTHIONEIN I; METALLOTHIONEIN II; METHYLMERCURY; THYROID HORMONE; THYROXINE; THYROXINE DEIODINASE;

EID: 33749594731     PISSN: 0300483X     EISSN: None     Source Type: Journal    
DOI: 10.1016/j.tox.2006.08.017     Document Type: Article
Times cited : (33)

References (54)
  • 2
    • 0036191639 scopus 로고    scopus 로고
    • Biochemistry, cellular and molecular biology, and physiological roles of the iodothyronine selenodeiodinase
    • Bianco A.C., Salvatore D., Gereben B., Berry M.J., and Larsen P.R. Biochemistry, cellular and molecular biology, and physiological roles of the iodothyronine selenodeiodinase. Endocr. Rev. 23 (2002) 38-89
    • (2002) Endocr. Rev. , vol.23 , pp. 38-89
    • Bianco, A.C.1    Salvatore, D.2    Gereben, B.3    Berry, M.J.4    Larsen, P.R.5
  • 3
    • 0017184389 scopus 로고
    • A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding
    • Bradford M.M. A rapid and sensitive method for the quantitation of microgram quantities of protein utilizing the principle of protein-dye binding. Anal. Biochem. 162 (1976) 248-254
    • (1976) Anal. Biochem. , vol.162 , pp. 248-254
    • Bradford, M.M.1
  • 4
    • 0024540448 scopus 로고
    • The effects of methylmercury on the developing brain
    • Choi B.H. The effects of methylmercury on the developing brain. Prog. Neurobiol. 32 (1989) 447-470
    • (1989) Prog. Neurobiol. , vol.32 , pp. 447-470
    • Choi, B.H.1
  • 5
    • 0017682086 scopus 로고
    • A study of extrathyroidal conversion of thyroxine (T4) to 3,3′,5-triiodothyronine (T3) in vitro
    • Chopra I.J. A study of extrathyroidal conversion of thyroxine (T4) to 3,3′,5-triiodothyronine (T3) in vitro. Endocrinology 101 (1977) 453-463
    • (1977) Endocrinology , vol.101 , pp. 453-463
    • Chopra, I.J.1
  • 6
    • 0029942808 scopus 로고    scopus 로고
    • Cadmium accumulation and metallothionein expression in brain of mice at different stages of development
    • Choudhuri S., Liu W.L., Berman N.E.J., and Klaassen C.D. Cadmium accumulation and metallothionein expression in brain of mice at different stages of development. Toxicol. Lett. 84 (1996) 127-133
    • (1996) Toxicol. Lett. , vol.84 , pp. 127-133
    • Choudhuri, S.1    Liu, W.L.2    Berman, N.E.J.3    Klaassen, C.D.4
  • 7
    • 0020051327 scopus 로고
    • An analysis of the sources and quantity of 3,5,3′-triiodothyronine specifically bound to nuclear receptors in rat cerebral cortex and cerebellum
    • Crantz F.R., Silva J.E., and Larsen P.R. An analysis of the sources and quantity of 3,5,3′-triiodothyronine specifically bound to nuclear receptors in rat cerebral cortex and cerebellum. Endocrinology 110 (1982) 367-375
    • (1982) Endocrinology , vol.110 , pp. 367-375
    • Crantz, F.R.1    Silva, J.E.2    Larsen, P.R.3
  • 8
    • 85047690484 scopus 로고    scopus 로고
    • Deubiquitination of type 2 iodothyronine deiodinase by von Hippel-Lindau protein-interacting deubiquitinating enzymes regulates thyroid hormone activation
    • Curcio-Morelli C., Zavacki A.M., Christofollete M., Gereben B., de Freitas B.C.G., Harney J.W., Li Z., Wu G., and Bianco A.C. Deubiquitination of type 2 iodothyronine deiodinase by von Hippel-Lindau protein-interacting deubiquitinating enzymes regulates thyroid hormone activation. J. Clin. Invest. 112 (2003) 189-196
    • (2003) J. Clin. Invest. , vol.112 , pp. 189-196
    • Curcio-Morelli, C.1    Zavacki, A.M.2    Christofollete, M.3    Gereben, B.4    de Freitas, B.C.G.5    Harney, J.W.6    Li, Z.7    Wu, G.8    Bianco, A.C.9
  • 9
    • 0022887521 scopus 로고
    • Distribution of cadmium, lead and zinc in lung, liver and kidney in long-term exposed smelter workers
    • Gerhardsson L., Brune D., Nordberg G.F., and Wester P.O. Distribution of cadmium, lead and zinc in lung, liver and kidney in long-term exposed smelter workers. Sci. Total Environ. 50 (1986) 65-85
    • (1986) Sci. Total Environ. , vol.50 , pp. 65-85
    • Gerhardsson, L.1    Brune, D.2    Nordberg, G.F.3    Wester, P.O.4
  • 10
    • 0018211506 scopus 로고
    • Postnatal endocrine dysfunction induced by prenatal methylmercury or cadmium exposure in mice
    • Grady R.R., and Kitay J.I. Postnatal endocrine dysfunction induced by prenatal methylmercury or cadmium exposure in mice. J. Environ. Pathol. Toxicol. 1 (1978) 187-197
    • (1978) J. Environ. Pathol. Toxicol. , vol.1 , pp. 187-197
    • Grady, R.R.1    Kitay, J.I.2
  • 11
    • 0027209056 scopus 로고
    • Neurochemical changes in developing rat brain after pre- and postnatal cadmium exposure
    • Gupta A., Gupta A., Murthy R.C., and Chandra S.V. Neurochemical changes in developing rat brain after pre- and postnatal cadmium exposure. Bull. Environ. Contam. Toxicol. 51 (1993) 12-17
    • (1993) Bull. Environ. Contam. Toxicol. , vol.51 , pp. 12-17
    • Gupta, A.1    Gupta, A.2    Murthy, R.C.3    Chandra, S.V.4
  • 12
    • 0031710731 scopus 로고    scopus 로고
    • Role of ascorbic acid in cadmium-induced thyroid dysfunction and lipid peroxidation
    • Gupta P., and Kar A. Role of ascorbic acid in cadmium-induced thyroid dysfunction and lipid peroxidation. J. Appl. Toxicol. 18 (1998) 317-320
    • (1998) J. Appl. Toxicol. , vol.18 , pp. 317-320
    • Gupta, P.1    Kar, A.2
  • 13
    • 0036018266 scopus 로고    scopus 로고
    • Mechanism of thyroid hormone action
    • Harvey C.B., and Williams G.R. Mechanism of thyroid hormone action. Thyroid 12 (2002) 441-446
    • (2002) Thyroid , vol.12 , pp. 441-446
    • Harvey, C.B.1    Williams, G.R.2
  • 14
    • 0002722866 scopus 로고    scopus 로고
    • Developmental neurotoxicity of cadmium
    • Slikker W., and Chang L.W. (Eds), London, Academic Press
    • Hastings L., and Miller M.L. Developmental neurotoxicity of cadmium. In: Slikker W., and Chang L.W. (Eds). Handbook of Developmental Neurotoxicology (1998), London, Academic Press 517-538
    • (1998) Handbook of Developmental Neurotoxicology , pp. 517-538
    • Hastings, L.1    Miller, M.L.2
  • 15
    • 25144444814 scopus 로고    scopus 로고
    • Structure and function of the type 3 deiodinase gene
    • Hernandez A. Structure and function of the type 3 deiodinase gene. Thyroid 15 (2005) 865-874
    • (2005) Thyroid , vol.15 , pp. 865-874
    • Hernandez, A.1
  • 16
    • 0022994702 scopus 로고
    • Acute endocrine effects of a single administration of methylmercury chloride (MMC) in rats
    • Kabuto M. Acute endocrine effects of a single administration of methylmercury chloride (MMC) in rats. Endocrinol. Jpn. 33 (1986) 683-690
    • (1986) Endocrinol. Jpn. , vol.33 , pp. 683-690
    • Kabuto, M.1
  • 17
    • 0018826826 scopus 로고
    • Phenolic and tyrosyl ring deiodination of iodothyronine in rat brain homogenates
    • Kaplan M.M., and Yaskoski K.A. Phenolic and tyrosyl ring deiodination of iodothyronine in rat brain homogenates. J. Clin. Invest. 66 (1980) 551-562
    • (1980) J. Clin. Invest. , vol.66 , pp. 551-562
    • Kaplan, M.M.1    Yaskoski, K.A.2
  • 18
    • 0030061160 scopus 로고    scopus 로고
    • Induction of metallothinein mRNA and protein in murine astrocyte cultures
    • Kramer K.K., Liu J., Choudhuri S., and Klaassen C.D. Induction of metallothinein mRNA and protein in murine astrocyte cultures. Toxicol. Appl. Pharmacol. 136 (1996) 94-100
    • (1996) Toxicol. Appl. Pharmacol. , vol.136 , pp. 94-100
    • Kramer, K.K.1    Liu, J.2    Choudhuri, S.3    Klaassen, C.D.4
  • 19
    • 0019754949 scopus 로고
    • Relationships between circulating and intracellular thyroid hormones: physiological and clinical implications
    • Larsen P.R., Silva J.E., and Kaplan M.M. Relationships between circulating and intracellular thyroid hormones: physiological and clinical implications. Endocr. Rev. 2 (1981) 87-102
    • (1981) Endocr. Rev. , vol.2 , pp. 87-102
    • Larsen, P.R.1    Silva, J.E.2    Kaplan, M.M.3
  • 21
    • 0029595386 scopus 로고
    • Transgenic mice that overexpress metallothionein-I are protected from cadmium lethality and hepatotoxicity
    • Liu Y., Liu J., Iszard M.B., Andrews G.K., Palmiter R.D., and Klaassen C.D. Transgenic mice that overexpress metallothionein-I are protected from cadmium lethality and hepatotoxicity. Toxicol. Appl. Pharmacol. 135 (1995) 222-228
    • (1995) Toxicol. Appl. Pharmacol. , vol.135 , pp. 222-228
    • Liu, Y.1    Liu, J.2    Iszard, M.B.3    Andrews, G.K.4    Palmiter, R.D.5    Klaassen, C.D.6
  • 23
    • 0027204069 scopus 로고
    • Targeting and germ-line transmission of a null mutation at the metallothionein I and II loci in mouse
    • Michalska A.E., and Choo K.H.A. Targeting and germ-line transmission of a null mutation at the metallothionein I and II loci in mouse. Proc. Natl. Acad. Sci. USA 90 (1993) 8088-8092
    • (1993) Proc. Natl. Acad. Sci. USA , vol.90 , pp. 8088-8092
    • Michalska, A.E.1    Choo, K.H.A.2
  • 24
    • 13444252428 scopus 로고    scopus 로고
    • The effects of gestational arsenic exposure and dietary selenium deficiency on selenium and selenoenzymes in maternal and fetal tissue in mice
    • Miyazaki K., Watanabe C., Mori K., Yoshida K., and Ohtsuka R. The effects of gestational arsenic exposure and dietary selenium deficiency on selenium and selenoenzymes in maternal and fetal tissue in mice. Toxicology 208 (2005) 357-365
    • (2005) Toxicology , vol.208 , pp. 357-365
    • Miyazaki, K.1    Watanabe, C.2    Mori, K.3    Yoshida, K.4    Ohtsuka, R.5
  • 25
    • 0022516717 scopus 로고
    • Accumulation of mercury in the anterior pituitary of rats following oral or intraperitoneal administration of methylmercury
    • Moller-Madson B., and Thorlacius-Ussing O. Accumulation of mercury in the anterior pituitary of rats following oral or intraperitoneal administration of methylmercury. Virchows Arch. B 51 (1986) 303-311
    • (1986) Virchows Arch. B , vol.51 , pp. 303-311
    • Moller-Madson, B.1    Thorlacius-Ussing, O.2
  • 26
    • 0027521812 scopus 로고
    • Inhibition of placental thyroxine 5-deiodinase activity decreases amniotic fluid concentration of 3,3′,5′-triiodothyronine in rat
    • Mori K., Yoshida K., Kaise K., Kaise N., Fukazawa H., Kikuchi K., Abe K., and Yoshinaga K. Inhibition of placental thyroxine 5-deiodinase activity decreases amniotic fluid concentration of 3,3′,5′-triiodothyronine in rat. Endocr. J. 40 (1993) 405-412
    • (1993) Endocr. J. , vol.40 , pp. 405-412
    • Mori, K.1    Yoshida, K.2    Kaise, K.3    Kaise, N.4    Fukazawa, H.5    Kikuchi, K.6    Abe, K.7    Yoshinaga, K.8
  • 27
    • 0029619841 scopus 로고
    • Thyroid hormone regulates rat placental type III iodothyronine deiodinase activity by inducing kinetic changes different from those in the same isozyme in rat brain
    • Mori K., Yoshida K., Fukazawa H., Kiso Y., Sayama N., Kikuchi K., Aizawa Y., and Abe K. Thyroid hormone regulates rat placental type III iodothyronine deiodinase activity by inducing kinetic changes different from those in the same isozyme in rat brain. Endocr. J. 42 (1995) 753-760
    • (1995) Endocr. J. , vol.42 , pp. 753-760
    • Mori, K.1    Yoshida, K.2    Fukazawa, H.3    Kiso, Y.4    Sayama, N.5    Kikuchi, K.6    Aizawa, Y.7    Abe, K.8
  • 28
    • 0029915796 scopus 로고    scopus 로고
    • Involvement of tyrosine phosphorylation in the regulation of 5′-deiodinases in FRTL-5 rat thyroid cells and rat astrocytes
    • Mori K., Stone S., Braverman L.E., and DeVito W.J. Involvement of tyrosine phosphorylation in the regulation of 5′-deiodinases in FRTL-5 rat thyroid cells and rat astrocytes. Endocrinology 137 (1996) 1313-1318
    • (1996) Endocrinology , vol.137 , pp. 1313-1318
    • Mori, K.1    Stone, S.2    Braverman, L.E.3    DeVito, W.J.4
  • 29
    • 29044438438 scopus 로고    scopus 로고
    • Methylmercury inhibits type II 5′-deiodinase activity in NB41A3 neuroblastoma cells
    • Mori K., Yoshida K., Tani J.-I., Hoshikawa S., Ito S., and Watanabe C. Methylmercury inhibits type II 5′-deiodinase activity in NB41A3 neuroblastoma cells. Toxicol. Lett. 161 (2006) 96-101
    • (2006) Toxicol. Lett. , vol.161 , pp. 96-101
    • Mori, K.1    Yoshida, K.2    Tani, J.-I.3    Hoshikawa, S.4    Ito, S.5    Watanabe, C.6
  • 31
    • 0022500285 scopus 로고
    • Subacute toxicity of methylmercuric chloride and mercuric chloride on mouse thyroid
    • Nishida M., Yamamoto T., Yoshimura Y., and Kawada J. Subacute toxicity of methylmercuric chloride and mercuric chloride on mouse thyroid. J. Pharmacobiodyn. 9 (1986) 331-338
    • (1986) J. Pharmacobiodyn. , vol.9 , pp. 331-338
    • Nishida, M.1    Yamamoto, T.2    Yoshimura, Y.3    Kawada, J.4
  • 33
    • 0015932509 scopus 로고
    • Methylmercury accumulation in brains of pregnant, non-pregnant and fetal rats
    • Null D.H., Gartside P.S., and Wei E. Methylmercury accumulation in brains of pregnant, non-pregnant and fetal rats. Life Sci. 12 (1973) 65-72
    • (1973) Life Sci. , vol.12 , pp. 65-72
    • Null, D.H.1    Gartside, P.S.2    Wei, E.3
  • 34
    • 0032717202 scopus 로고    scopus 로고
    • Exposure to polychlorinated biphenyls and levels of thyroid hormones in children
    • Osius N., Karmaus W., Kruse H., and Witten J. Exposure to polychlorinated biphenyls and levels of thyroid hormones in children. Environ. Health Perspect. 107 (1999) 843-849
    • (1999) Environ. Health Perspect. , vol.107 , pp. 843-849
    • Osius, N.1    Karmaus, W.2    Kruse, H.3    Witten, J.4
  • 35
    • 0027446957 scopus 로고
    • The role of thyroid hormones in prenatal and neonatal neurological development-current perspectives
    • Porterfield S.P., and Hendrich C.E. The role of thyroid hormones in prenatal and neonatal neurological development-current perspectives. Endocr. Rev. 14 (1993) 94-106
    • (1993) Endocr. Rev. , vol.14 , pp. 94-106
    • Porterfield, S.P.1    Hendrich, C.E.2
  • 36
    • 0017581783 scopus 로고
    • Cadmium alters behaviour and the biosynthetic capacity for catecholamines and serotonin in neonatal rat brain
    • Rastogi R.B., Merali Z., and Singhal R.L. Cadmium alters behaviour and the biosynthetic capacity for catecholamines and serotonin in neonatal rat brain. J. Neurochem. 28 (1977) 789-794
    • (1977) J. Neurochem. , vol.28 , pp. 789-794
    • Rastogi, R.B.1    Merali, Z.2    Singhal, R.L.3
  • 37
    • 0029156314 scopus 로고
    • Metallothionein induction in neonatal rat primary astrocyte cultures protects against methylmercury cytotoxicity
    • Rising L., Vitarella D., Kimelberg H.K., and Aschner M. Metallothionein induction in neonatal rat primary astrocyte cultures protects against methylmercury cytotoxicity. J. Neurochem. 65 (1995) 1562-1568
    • (1995) J. Neurochem. , vol.65 , pp. 1562-1568
    • Rising, L.1    Vitarella, D.2    Kimelberg, H.K.3    Aschner, M.4
  • 39
    • 0018177742 scopus 로고
    • The contribution of local tissue thyroxine monodeiodination to the nuclear 3,5,3′-triiodothyronine in pituitary, liver and kidney of euthyroid rats
    • Silva J.E., Dick T.E., and Larsen P.R. The contribution of local tissue thyroxine monodeiodination to the nuclear 3,5,3′-triiodothyronine in pituitary, liver and kidney of euthyroid rats. Endocrinology 103 (1978) 1196-1207
    • (1978) Endocrinology , vol.103 , pp. 1196-1207
    • Silva, J.E.1    Dick, T.E.2    Larsen, P.R.3
  • 40
    • 0021888704 scopus 로고
    • Regulation of rat cerebrocortical and adenohypophyseal type II 5′-deiodinase by thyroxine, triiodothyronine, and reverse triiodothyronine
    • Silva J.E., and Leonard J.L. Regulation of rat cerebrocortical and adenohypophyseal type II 5′-deiodinase by thyroxine, triiodothyronine, and reverse triiodothyronine. Endocrinology 116 (1985) 1627-1635
    • (1985) Endocrinology , vol.116 , pp. 1627-1635
    • Silva, J.E.1    Leonard, J.L.2
  • 41
    • 0032423089 scopus 로고    scopus 로고
    • Type 2 iodothyronine deiodinase in rat pituitary tumor cells is inactivated in proteasomes
    • Steinsapir J., Harney J., and Larsen P.R. Type 2 iodothyronine deiodinase in rat pituitary tumor cells is inactivated in proteasomes. J. Clin. Invest. 102 (1998) 1895-1899
    • (1998) J. Clin. Invest. , vol.102 , pp. 1895-1899
    • Steinsapir, J.1    Harney, J.2    Larsen, P.R.3
  • 43
  • 44
    • 0017112685 scopus 로고
    • Subcellular localization of a rat enzyme converting thyroxine into tri-iodothyronine and possible involvement of essential thiol groups
    • Visser T.J., van der Does-Tobe I., Doctor R., and Hennemann G. Subcellular localization of a rat enzyme converting thyroxine into tri-iodothyronine and possible involvement of essential thiol groups. Biochem. J. 157 (1976) 479-482
    • (1976) Biochem. J. , vol.157 , pp. 479-482
    • Visser, T.J.1    van der Does-Tobe, I.2    Doctor, R.3    Hennemann, G.4
  • 45
    • 0032918607 scopus 로고    scopus 로고
    • In utero methylmercury exposure differentially affects the activities of selenoenzymes in the fetal mouse brain
    • Watanabe C., Yoshida K., Kasanuma Y., Kun Y., and Satoh H. In utero methylmercury exposure differentially affects the activities of selenoenzymes in the fetal mouse brain. Environ. Res. 80 (1999) 208-214
    • (1999) Environ. Res. , vol.80 , pp. 208-214
    • Watanabe, C.1    Yoshida, K.2    Kasanuma, Y.3    Kun, Y.4    Satoh, H.5
  • 46
    • 23844524787 scopus 로고    scopus 로고
    • Perinatal and lifetime exposure to methylmercury in the mouse: behavioral effects
    • Weiss B., Stern S., Cox C., and Balys M. Perinatal and lifetime exposure to methylmercury in the mouse: behavioral effects. Neurotoxicology 26 (2005) 675-690
    • (2005) Neurotoxicology , vol.26 , pp. 675-690
    • Weiss, B.1    Stern, S.2    Cox, C.3    Balys, M.4
  • 47
    • 0842308023 scopus 로고    scopus 로고
    • 2,3,7,8-Tetrachlorodibenzo-p-dioxin augments the modulation of gene expression mediated by the thyroid hormone receptor
    • Yamada-Okabe T., Aono T., Sakai H., Kashima Y., and Yamada-Okabe H. 2,3,7,8-Tetrachlorodibenzo-p-dioxin augments the modulation of gene expression mediated by the thyroid hormone receptor. Toxicol. Appl. Pharmacol. 194 (2004) 201-210
    • (2004) Toxicol. Appl. Pharmacol. , vol.194 , pp. 201-210
    • Yamada-Okabe, T.1    Aono, T.2    Sakai, H.3    Kashima, Y.4    Yamada-Okabe, H.5
  • 48
    • 0008266881 scopus 로고    scopus 로고
    • Foreign metallothionein-I expression by transient transfection in MT-I and MT-II null astrocytes confers increased protection against acute methylmercury cytotoxicity
    • Yao C.P., Allen J.W., Mutkus L.A., Xu S.B., Tan K.H., and Aschner M. Foreign metallothionein-I expression by transient transfection in MT-I and MT-II null astrocytes confers increased protection against acute methylmercury cytotoxicity. Brain Res. 855 (2000) 32-38
    • (2000) Brain Res. , vol.855 , pp. 32-38
    • Yao, C.P.1    Allen, J.W.2    Mutkus, L.A.3    Xu, S.B.4    Tan, K.H.5    Aschner, M.6
  • 51
    • 3242759070 scopus 로고    scopus 로고
    • Susceptibility of metallothionein-null mice to the behavioral alterations caused by exposure to mercury vapor at human-relevant concentration
    • Yoshida M., Watanabe C., Satoh M., Yasutake A., Sawada M., Ohtsuka Y., Akama Y., and Tohyama C. Susceptibility of metallothionein-null mice to the behavioral alterations caused by exposure to mercury vapor at human-relevant concentration. Toxicol. Sci. 80 (2004) 69-73
    • (2004) Toxicol. Sci. , vol.80 , pp. 69-73
    • Yoshida, M.1    Watanabe, C.2    Satoh, M.3    Yasutake, A.4    Sawada, M.5    Ohtsuka, Y.6    Akama, Y.7    Tohyama, C.8
  • 53
    • 0037330297 scopus 로고    scopus 로고
    • Challenges confronting risk analysis of potential thyroid toxicants
    • Zoeller R.T. Challenges confronting risk analysis of potential thyroid toxicants. Risk Anal. 23 (2003) 143-162
    • (2003) Risk Anal. , vol.23 , pp. 143-162
    • Zoeller, R.T.1
  • 54
    • 0034465692 scopus 로고    scopus 로고
    • Developmental exposure to polychlorinated biphenyls exerts thyroid hormone-like effects on the expression of RC3/neurogranin and myelin basic protein messenger ribonucleic acids in the developing rat brain
    • Zoeller R.T., Dowling A.L.S., and Vas A.A. Developmental exposure to polychlorinated biphenyls exerts thyroid hormone-like effects on the expression of RC3/neurogranin and myelin basic protein messenger ribonucleic acids in the developing rat brain. Endocrinology 141 (2000) 181-189
    • (2000) Endocrinology , vol.141 , pp. 181-189
    • Zoeller, R.T.1    Dowling, A.L.S.2    Vas, A.A.3


* 이 정보는 Elsevier사의 SCOPUS DB에서 KISTI가 분석하여 추출한 것입니다.