碩士 / 國立嘉義大學 / 水產生物學系研究所 / 94 / Thyroid-mediated development and metamorphosis of teleosts are well documented however knowledge on thyroid-mediated otolith growth is still unclear. Experiments were conducted to understand the effect of thyroxin (T3) and thiourea (TU) on the teleostean otolith growth and to evaluate the relationship between otolith growth and T3 profiles .Methods: (1)Tilapia (Oreochromis mossambicus) larvae at 3dph (days post hatching) were treated with 25ppb T3 and 300ppm TU or without treatment for 13 day. Otolith length, daily growth increment, and the thyroxin content were measured on 14 day. The otolith radius were 156.0 ± 18.8 �慆, 171.7 ± 18.8 �慆 and 147.9 ± 10.6�慆 in control,T3 group and TU group, respectively. The otolith radius of T3 group was significantly larger than control and TU group (p < 0.05) while the radius of control and TU groups were not significantly different (p > 0.05). The daily growth increments among treatments were not significantly different. The thyroxin content of T3 group (4.79 ± 0.42 ng/g) was also significantly larger than control fish (1.36 ± 0.35 ng/g) and TU group (0.61 ± 0.48 ng/g). (2) Tilapia juveniles at 16 dph were treated with different TU concentration (300ppm、600ppm、900ppm)and 25ppb T3 or without treatment for 13 days. After the experimental period, the newly grown otolith length and daily growth increment in 300ppm TU、600ppm TU and 900ppm TU group were 45.4 ± 6.07�慆; 11.0 ± 0.9 rings、34.8 ± 6.9 �慆; 9.0 ± 0.9 rings and 33.2 ± 4.8 �慆; 9.2 ± 1.1 rings, which were all significantly smaller than control fish (80.45 ± 27.24�慆; 13.0 ± 1.3 rings) (p < 0.05). The thyroxin content of T3 group (9.74 ± 2.13 ng/g) was also significantly larger than control fish (1.40 ± 0.15 ng/g) and TU group (0.32 ± 0.07 ng/g).These results indicate that: 1)Ontogenetic growth of otolith is consistent with T3 profile. 2) T3 and TU show stage-specific promotion and inhibition of otolith and somatic growth, respectively. 3) Otolith growth is influenced by thyroid hormone in Tilapia and very likely in other teleosts as well.
| Identifer | oai:union.ndltd.org:TW/094NCYU5613012 |
| Date | January 2004 |
| Creators | Yi-Ping Hwang, 黃奕萍 |
| Contributors | Su-Mei Wu, 吳淑美 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 79 |
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