Gullian Klanian Mariel, Zapata Pérez Omar, Vela-Magaña Miguel Angel
Universidad Marista de Mérida, Periférico Norte Tablaje Catastral 13941 Carretera Mérida- Progreso, Post Office Box 97300, Mérida, Yucatán, Mexico.
CINVESTAV-IPN, Unidad Mérida Km 6 Antigua Carretera a Progreso, Cordemex, 97310, Mérida, Yucatán, Mexico.
Fish Physiol Biochem. 2018 Feb;44(1):73-85. doi: 10.1007/s10695-017-0414-8. Epub 2017 Sep 12.
Red drum (Sciaenops ocellatus) is a euryhaline fish commonly found in the Gulf of Mexico and along the Atlantic coast of North America. Because of high commercial demand and its euryhaline characteristics, aquaculture of this species has diversified from marine to low-salinity aquaculture systems. In recent years, interest in the feasibility of producing red drum in inland freshwater systems has grown and this prompted us to investigate its osmoregulatory capacity after rearing for 8 months in a freshwater aquaculture system. We compared the activities of several genes and enzymes involved in the osmoregulatory process in freshwater-acclimatized (FW) and seawater (SW) red drum. The gene expression profiles were variable: the expression of genes encoding Na/K-ATPase (NKA) and the cystic fibrosis transmembrane regulator (CFTR) was slightly higher in SW than FW fish, while phosphoenolpyruvate carboxykinase (PEPCK) and the glucocorticoid receptor messenger RNA (mRNA) levels were higher in FW red drum. The total plasma K concentration was 60.3% lower, and gill NKA activity was 63.5% lower in FW than in SW fish. PEPCK activity was twofold higher in FW than in SW red drum. Similarly, liver glycogen was 60% higher in FW fish. In summary, both gene expression and the enzyme activity data support the phenotypic plasticity of red drum and suggest that the limited capacity for ion homeostasis observed, in particular the low plasma K concentration, was due to the composition of freshwater and does not necessarily reflect a physiological inability to osmoregulate.
红鼓鱼（眼斑拟石首鱼）是一种广盐性鱼类，常见于墨西哥湾和北美洲大西洋沿岸。由于商业需求高及其广盐性特征，该物种的水产养殖已从海洋养殖系统多样化到低盐度养殖系统。近年来，人们对在内陆淡水系统中养殖红鼓鱼的可行性兴趣增加，这促使我们研究其在淡水养殖系统中饲养8个月后的渗透调节能力。我们比较了淡水驯化（FW）和海水（SW）红鼓鱼中参与渗透调节过程的几种基因和酶的活性。基因表达谱各不相同：编码钠/钾-ATP酶（NKA）和囊性纤维化跨膜传导调节因子（CFTR）的基因在SW鱼中的表达略高于FW鱼，而磷酸烯醇式丙酮酸羧激酶（PEPCK）和糖皮质激素受体信使核糖核酸（mRNA）水平在FW红鼓鱼中更高。FW鱼的血浆总钾浓度比SW鱼低60.3%，鳃NKA活性比SW鱼低63.5%。FW红鼓鱼的PEPCK活性比SW鱼高两倍。同样，FW鱼的肝糖原含量高60%。总之，基因表达和酶活性数据都支持红鼓鱼的表型可塑性，并表明观察到的离子稳态能力有限，特别是低血浆钾浓度，是由于淡水的成分，不一定反映生理上无法进行渗透调节。
