Magnesium transport in the aglomerular kidney of the Gulf toadfish (Opsanus beta)
Magnesium transport in the aglomerular kidney of the Gulf toadfish (Opsanus beta)
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DOI：
10.1007/s00360-021-01392-8
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发表时间：
2021-07-23
影响因子：
2
通讯作者：
Grosell, Martin
中科院分区：
文献类型：
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作者：
Hansen, Nina G. Walker;Madsen, Steffen S.;Grosell, Martin
尽管有一个无肾小球肾，海湾蟾鱼可以生存在水从近新鲜高达70千分之一的盐度。在高渗环境中，主要的肾功能是平衡来自环境的被动Mg 2+负荷，并具有相等的排泄。然而，参与Mg 2+分泌的分子转运蛋白知之甚少。我们研究了环境MgCl 2单独或与高盐度组合是否影响经典参与肾Mg 2+分泌的基因（slc 41 a1，slc 41 a3，cnnm 3）以及三个新基因（trpm 6，trpm 7，claudin-19）和Na+/K+-ATP酶α亚基的两种亚型（nka-α 1a，nka-α 1b）的转录调控。首先，蟾鱼适应5，9，35，或60 ppt的水（相当于类似的7，13，50和108 mmol L-1的环境[Mg 2 +]，分别），并在24小时或9天取样。接下来，通过将蟾鱼暴露于对照（50 mmol L-1 Mg 2+）或在恒定盐度下升高的[Mg 2 +]（100 mmol L-1）7天来探索升高的环境[Mg 2 +]的影响。本实验中的Mg 2+水平与第一次实验中的对照和高盐条件下的水平相对应。盐度从5到60 ppt的增加刺激了肾脏中所有研究的转录物的水平。在Mg 2+暴露的鱼，我们观察到的肠液和血浆渗透压升高和[Mg 2 +]的体积增加了14倍，这表明了巨大的监管挑战。然而，与对照组相比，没有一个肾脏基因靶点改变表达。我们的结论是，肾Mg 2+转运蛋白的转录调控诱导升高[Mg 2 +]结合盐度，而不是升高的环境[Mg 2 +]单独。
Despite having an aglomerular kidney, Gulf toadfish can survive in water ranging from nearly fresh up to 70 parts per thousand salinity. In hyperosmotic environments, the major renal function is to balance the passive Mg2+ load from the environment with an equal excretion. However, the molecular transporters involved in Mg2+ secretion are poorly understood. We investigated whether environmental MgCl2 alone or in combination with elevated salinity affected transcriptional regulation of genes classically involved in renal Mg2+ secretion (slc41a1, slc41a3, cnnm3) together with three novel genes (trpm6, trpm7, claudin-19) and two isoforms of the Na+/K+-ATPase alpha-subunit (nka-alpha 1a, nka-alpha 1b). First, toadfish were acclimated to 5, 9, 35, or 60 ppt water (corresponding to similar to 7, 13, 50 and 108 mmol L-1 ambient [Mg2+], respectively) and sampled at 24 h or 9 days. Next, the impact of elevated ambient [Mg2+] was explored by exposing toadfish to control (50 mmol L-1 Mg2+), or elevated [Mg2+] (100 mmol L-1) at a constant salinity for 7 days. Mg2+ levels in this experiment corresponded with levels in control and hypersaline conditions in the first experiment. A salinity increase from 5 to 60 ppt stimulated the level of all investigated transcripts in the kidney. In Mg2+-exposed fish, we observed a 14-fold increase in the volume of intestinal fluids and elevated plasma osmolality and [Mg2+], suggesting osmoregulatory challenges. However, none of the renal gene targets changed expression compared with the control group. We conclude that transcriptional regulation of renal Mg2+ transporters is induced by elevated [Mg2+] in combination with salinity rather than elevated ambient [Mg2+] alone.