碩士 / 東海大學 / 生物學系 / 87 / Abstract
Calcium ion is essential to larvae development and growth. Most of previous studies on calcium balance examined only the calcium influx and it was assumed that calcium efflux remained minimal. No comparison was done in terms of the rates of modulation between influx and efflux. This was, in part, because the technical difficulty in measuring calcium efflux in fish larvae. The present study, using different calcium concentration as environmental factors, investigated the calcium balance mechanism in developing tilipia larvae. In addition, the methodology for calcium efflux in tilapia larvae was established.
Upon 48 hours after fertilization, eggs were incubated respectively in sufficient- and low-calcium (1 mM and 0.02 mM) artificial water. Calcium influx was measured on days 0, 3, and 6 after hatching. Larvae in low-calcium water had lower calcium influx from day 0 to day 3 after hatching. After 6 days of exposure, the low-calcium larvae had a similar influx as the sufficient-calcium larvae. Efflux was decreased from day 0 to day 6 after hatching. In the challenge experiment, fertilized eggs were incubated in normal calcium concentration ([Ca2+]=0.2 mM) medium and transferred to sufficient- and low-calcium artificial water 0 or 3 days after hatching. In 0-day-old larvae from low-calcium medium, efflux decreased after 44 hours of exposure, while influx increased to the level of the sufficient-calcium level after 68 hours of exposure. 3-day-old larvae from low-calcium condition decreased efflux after 22 hours of exposure, and influx increased after 39 hours. The calcium content in low-calcium larvae was lower than that in sufficient-calcium larvae throughout the experiment.
My study indicated that the abilities to modulate calcium influx and efflux in larvae varied with different acclimation periods and developmental stages. Calcium influx in tilapia larvae increased rapidly in development period. Calcium efflux remained stable, and much lower than calcium influx. The calcium content in larvae accumulated rapidly during the development period. Compared to calcium efflux, calcium influx plays a major role in calcium content accumulation during the early development period. It took less time to decrease efflux than to increase influx. 3-day-old larvae have the better ability to calcium modulation. Increasing influx and decreasing efflux is a compensation for less calcium content in the larvae adapted to low-calcium environment.
| Identifer | oai:union.ndltd.org:TW/087THU00112007 |
| Date | January 1999 |
| Creators | Chou Ming-yi, 周銘翊 |
| Contributors | Lin Hui-Chen, 林惠真 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 50 |
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