Spatiotemporal expression pattern of the zebrafish aquaporin 8 family during early developmental stages.

Aquaporin 8 (Aqp8) is a transmembrane protein that is selectively permeated by water and some small solutes, and physiologically contributes to acid-base equilibrium in the gastrointestinal tract. Here, we described the characterization and spatiotemporal expression pattern of zebrafish aqp8 (zaqp8) gene family, including zaqp8a.1, zaqp8a.2, and zaqp8b, during the early developmental stages. The expression of zaqp8a.1 started first in the lateral plate mesoderm at the 12-somite stage (ss) and then expanded sequentially to the dorsal aorta, intersegmental blood vessels and then to the dorsal longitudinal anastomotic vessel at 24 h post fertilization (hpf). At 28 hpf, expression of zaqp8a.1 was also detected in the embryonic heart tube. Four days post fertilization (dpf), strong zaqp8a.1 expression was detected in the gastrointestinal tract and liver. By 72 hpf, the expression of zaqp8a.2 was first detected in the primitive gut region but not detected in the liver. The expression of zaqp8b was first detected in the intermediate mesoderm at 10 ss. From 24 hpf to 6 dpf, the proximal convoluted segment of the embryonic kidney was marked by zaqp8b expression Overall, these differential expression patterns of aqp8a.1, aqp8a.2, and aqp8b suggest that they possibly play distinct roles throughout the embryonic development by controlling or maintaining organ-specific cellular water homeostasis. Our study provides new evidence that organogenesis requires differential roles of Aqp8 proteins in zebrafish.