碩士 / 國立臺灣海洋大學 / 生物科技研究所 / 96 / Abstract
Brain is a highly energy consuming organ and sensitive to energy perturbations. Previous studies have found that environmental factors would induce changes in brain intracellular homeostasis and energy parameters. In recent studies, fish appeared to use lactate as an energy substrate during acclimation and exposure to severe environment changes. Nevertheless, the mechanism of the lactate transportation in brain during acclimation in low temperature is still unknown.
The lactate transporters, monocarboxylate transporters (MCTs), comprised 14 members and only the first four (MCT1-MCT4) have been demonstrated to be responsible for monocarboxylates (lactate, pyruvate, and ketone bodies) transportation. In the present study, homologues of MCT1-4 in zebrafish have been cloned and sequenced. RT-PCR results denoted that zMCT1-4 all expressed in brain. Real-time PCR was utilized to examine the cold-shock (18°C) effect on the zMCT1-4 transcripts in brains of zebrafish. Only the expression of zMCT2 was significantly decreased during periods of cold acclimation. Nevertheless, zMCT3 transcript maintained stable in face of ambient low temperature. Besides, expression of zMCT1 and -4 were up-regulated at 1-d 18°C transfer; thereafter, in 1-wk acclimation, zMCT4 levels still higher than control (28°C) and expression of zMCT1 returned to control level. Furthermore, in 18°C cold exposure, lactate contents in the plasma of zebrafish brain were decreased significantly in 1-h and 1-d acclimation, and then recovered to the control ones. In addition, apoptosis cells were detected in brain after 1-h 18°C exposure. Afterwards, death cells were decreased in 1-d acclimation. The phenomenon implied that lactate utilization was advantageous to brain cells survival in cold temperature. Subsequently, functional analysis provided the lactate transport evidences of zMCTs in 25°C compared with the 18°C with Xenopus oocytes. Only the kinetic of zMCT2 lactate transport was affected by cold stress. However, analysis of zMCT1 and zMCT3 were appeared stable during cold shock period.
In conclusion, each zMCT isoform with specific characteristics can fulfill their respective physiological demands and relevant energy supply in zebrafish brain during cold acclimation.
| Identifer | oai:union.ndltd.org:TW/096NTOU5111005 |
| Date | January 2008 |
| Creators | Sian-Tai Liu, 劉咸台 |
| Contributors | Pung-Pung Hwang, 黃鵬鵬 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 59 |
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