The responses of zebrafish (Danio rerio) to high external ammonia and urea transporter inhibition: nitrogen excretion and expression of rhesus glycoproteins and urea transporter proteins
The responses of zebrafish (Danio rerio) to high external ammonia and urea transporter inhibition: nitrogen excretion and expression of rhesus glycoproteins and urea transporter proteins
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DOI：
10.1242/jeb.034157
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发表时间：
2009-12-01
影响因子：
2.8
通讯作者：
Perry, Steve F.
中科院分区：
文献类型：
--
作者：
Braun, Marvin H.;Steele, Shelby L.;Perry, Steve F.
虽然成年斑马鱼（Danio rerio）在许多组织中都含有氨和尿素转运蛋白（分别为Rh和UT蛋白），但它们主要集中在鳃中。UT在Na(+)-K(+)- atp酶（NKA）型富含线粒体的细胞中具有弥漫性表达模式，Rh蛋白形成与河豚鳃相似的网络（Nakada et al., 2007b）。Rhag的表达似乎仅限于沿片层血腔排列的柱细胞，而Rhbg则定位于片层和丝层的外层，即铺装细胞上。暴露于高外部氨（HEA）或根皮素分别增加了成年和幼年斑马鱼组织中氨和尿素的水平；然而，对这些压力源的反应是年龄相关的。HEA增加了胚胎和幼虫中许多Rh蛋白的mRNA水平，但在成年鳃中没有引起类似的影响，这似乎通过增加v型H(+)- atp酶的表达来补偿不利的氨排泄梯度。暴露于根皮素可增加胚胎和幼虫的UT mRNA水平，但对成虫鳃组织无影响。令人惊讶的是，在成虫和幼虫中，HEA增加了UT的mRNA表达，而根皮素增加了Rh蛋白的mRNA表达。这些结果表明，在斑马鱼中，氨和尿素排泄之间的联系可能比大多数硬骨鱼中认为的更紧密。
While adult zebrafish, Danio rerio, possess ammonia and urea transporters (Rh and UT proteins, respectively) in a number of tissues, they are most heavily concentrated within the gills. UT has a diffuse expression pattern within Na(+)-K(+)-ATPase (NKA)-type mitochondrion-rich cells and Rh proteins form a network similar to the arrangement seen in pufferfish gills (Nakada et al., 2007b). Rhag expression appeared to be limited to the pillar cells lining the blood spaces of the lamellae while Rhbg was localized to the outer layer of both the lamellae and the filament, upon the pavement cells. Exposure to high external ammonia (HEA) or phloretin increased tissue levels of ammonia and urea, respectively, in adult and juvenile zebrafish; however, the responses to these stressors were age dependent. HEA increased mRNA levels for a number of Rh proteins in embryos and larvae but did not elicit similar effects in adult gills, which appear to compensate for the unfavourable ammonia excretory gradient by increasing expression of V-type H(+)-ATPase. Phloretin exposure increased UT mRNA levels in embryos and larvae but was without effect in adult gill tissue. Surprisingly, in both adults and juveniles, HEA increased the mRNA expression of UT and phloretin increased the mRNA expression of Rh proteins. These results imply that, in zebrafish, there may be a tighter link between ammonia and urea excretion than is thought to occur in most teleosts.