| Summary: | 碩士 === 國立臺灣師範大學 === 生命科學研究所 === 97 === Acid-base regulation is crucial for fish to cope with environmental pH changes particularly during embryonic and larval development. H+-ATPase-rich cells (HRCs) in the skin of zebrafish larvae are the major sites for H+ secretion. In this study, I examined the short-term (in hours) regulation of H+ secretion in zebrafish subjected to ambient pH changes. Scanning electron microscopy (SEM) and confocal microscopy were used to observe and quantify the apical surface (membrane) of HRCs. Whole body pH and H+ secreting by the skin of larvae were measured with scanning ion-selective electrode technique (SIET). Results showed that whole body H+ concentration significantly increased in the larvae transferred from pH 7 to pH 4 for 30 min. The apical surface area and density of HRCs were higher in pH 4 than in pH 7 acclimated larvae. As early as 10 min after being transferred from pH 4 to pH 7, the apical surface area dramatically decreased, meanwhile morphological change and internalization of the apical surface were observed. Down-regulation of H+ secretion was also found after the transfer. In contrast, when the larvae were transferred from pH 7 to pH 4, the apical surface gradually increased after 4 h.
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