博士 / 國立海洋大學 / 漁業科學學系 / 87 / In order to investigate the toxic effects of tributyltin (TBT) on marine teleosts, the gill and sensory tissue (vision, olfactory and gustatory) of thornfish (Terapon jarbua Forsskal) were obtained to study the physiological and behavioural changes.
1. Toxic effects of TBT on gill and cornea
The gill epithelial cells showed swelling and necrosis after exposure of TBT (10, 50 and 100 mg/l) for 7 d, the oxygen consumption also significantly increased from 0.019±0.002 (control) to 0.027±0.003 mg/l.g.min (10mg/l), then decreased to 0.020±0.003 and 0.013±0.002 mg/l.g.min (50, 100mg/l). However, the osmolity was not changed in TBT (1, 5 and 10 mg/l) exposure. In analysis of retinomotor response, the width of pigmented layer decreased from 75.33±2.88% (control) to 71.33±4.50、69.50±2.12及 63.33±4.04%. The visual ability was significantly affected.
2. Toxic effects of TBT on olfactory and gustatory
In SEM observation and electrophysiological recording, deformity and sloughing of the microvilli and cilia were observed after exposure of TBT (1 and 5 mg/l) for 7 d, the olfactory response were also decrease form -3.0 ± 0.6 mV to -1.3 ± 0.5 mV (1 mg/l) and -0.4 ± 0.1 (5 mg/l), respectively. The cilia of taste buds also showed degeneration, the gustatory response decreased from 100% to 58.3 % and 30.5%. The morphological examination of present results indicated that the membrane alteration might result from contact with TBT.
3. The toxic effects of TBT on mandibularis nerve and taste buds
In order to understand the toxic mechanism, the mandibularis n. and taste buds was exposed to TBT (10, 100, 1000mg/l) for 5 min and measured the gustatory response, respectively.
i. The treated mandibularis n. showed decline in transferring gustatory response after TBT exposure. After removement of TBT, the response of 10 and 100 mg/l groups recovered after 10 - 15 min.
ii. In the addition of dithiothretiol (DTT) after TBT (1000 mg/l) treatment, the treated mandibularis n. showed completely recovery.
iii. The TBT treated taste buds (1000 mg/l) showed decline in response and were not recoverable.
iiii. In the addition of DTT, the taste buds showed recovery.
4. The toxic effects of TBT on behaviour and muscle morphology
Decrease in C-startle responses (to flash light stimuli) and the swimming activity were observed in TBT (1 and 5 mg/l) exposure for 60 d. In morphological examination, 1 and 5 mg/l TBT groups showed vacuolation among myofibrils, the decrease and broke of muscle fibril was also found. After morphometric analysis, the relative area of vacuolation was significantly increased. In TEM observation of muscle cell, the swelling of mitochondria and degeneration in cristae were also observed.
The results suggested that retinomotor response, olfactory and gustatory response and C-startle response were highly sensitive to environmental changes, thus these physical responses could be used as a reliable index of environmental safety. The olfactory and gustatory observation also revealed significant alternation in membrane. Further, by recording on mandibularis nerve, the TBT toxicity were found to be reversible, therefore the binding reaction to membrane protein might not directly relevant with nerve function, the main mechanism might probably relate with its lipophilic character.
| Identifer | oai:union.ndltd.org:TW/087NTOU0451014 |
| Date | January 1999 |
| Creators | Dar Yi Wang, 王達益 |
| Contributors | Bao Quey Huang, 黃寶貴 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 128 |
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