Effects of inorganic mercury and methylmercury on osteoclasts and osteoblasts in the scales of the marine teleost as a model system of bone.
To evaluate the effects of inorganic mercury (InHg) and methylmercury (MeHg) on bone metabolism in a marine teleost, the activity of tartrate-resistant acid phosphatase (TRAP) and alkaline phosphatase (ALP) as indicators of such activity in osteoclasts and osteoblasts, respectively, were examined in scales of nibbler fish (Girella punctata). We found several lines of scales with nearly the same TRAP and ALP activity levels. Using these scales, we evaluated the influence of InHg and MeHg. TRAP activity in the scales treated with InHg (10(-5) and 10(-4) M) and MeHg (10(-6) to 10(-4) M) during 6 hrs of incubation decreased significantly. In contrast, ALP activity decreased after exposure to InHg (10(-5) and 10(-4) M) and MeHg (10(-6) to 10(-4) M) for 18 and 36 hrs, although its activity did not change after 6 hrs of incubation. As in enzyme activity 6 hrs after incubation, mRNA expression of TRAP (osteoclastic marker) decreased significantly with InHg and MeHg treatment, while that of collagen (osteoblastic marker) did not change significantly. At 6 hrs after incubation, the mRNA expression of metallothionein, which is a metal-binding protein in osteoblasts, was significantly increased following treatment with InHg or MeHg, suggesting that it may be involved in the protection of osteoblasts against mercury exposure up to 6 hrs after incubation. To our knowledge, this is the first report of the effects of mercury on osteoclasts and osteoblasts using marine teleost scale as a model system of bone.
1 Noto Marine Laboratory, Institute of Nature and Environmental Technology, Kanazawa University, Housu-gun, Ishikawa 927-0553, Japan.
Koji
K
Yachiguchi
Toshio
T
Sekiguchi
Masaki
M
Nakano
Atsuhiko
A
Hattori
Megumi
M
Yamamoto
Kei-ichiro
K
Kitamura
Masahiro
M
Maeda
Yoshiaki
Y
Tabuchi
Takashi
T
Kondo
Hiromitsu
H
Kamauchi
Hajime
H
Nakabayashi
Ajai K
AK
Srivastav
Kazuichi
K
Hayakawa
Tatsuya
T
Sakamoto
Nobuo
N
Suzuki
D000135:Acid Phosphatase / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D000818:Animals; D001842:Bone and Bones / Q000187:drug effects*; D024042:Collagen Type I / Q000235:genetics / Q000378:metabolism; D005399:Fishes / Q000033:anatomy & histology*; D005786:Gene Expression Regulation / Q000187:drug effects; D034582:Integumentary System / Q000502:physiology; D007527:Isoenzymes / Q000235:genetics / Q000378:metabolism; D008628:Mercury / Q000633:toxicity*; D008767:Methylmercury Compounds / Q000633:toxicity*; D008928:Mitochondria / Q000378:metabolism; D010006:Osteoblasts / Q000187:drug effects; D010010:Osteoclasts / Q000187:drug effects; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D000071681:Tartrate-Resistant Acid Phosphatase; D014874:Water Pollutants, Chemical / Q000633:toxicity
D024042:Collagen Type I; D007527:Isoenzymes; D008767:Methylmercury Compounds; D012333:RNA, Messenger; D014874:Water Pollutants, Chemical; D000135:Acid Phosphatase; D000071681:Tartrate-Resistant Acid Phosphatase; D008628:Mercury; C004925:methylmercuric chloride
inorganic mercury; methylmercury; nibbler fish; osteoblasts; osteoclasts; scales