Great Lakes WATER Institute, University of Wisconsin-Milwaukee, Milwaukee, WI, USA.
Comp Biochem Physiol A Mol Integr Physiol. 2009 Dec;154(4):465-73. doi: 10.1016/j.cbpa.2009.07.023. Epub 2009 Aug 3.
Zebrafish (Danio rerio) have become an important model organism for developmental biology and human health studies. We recently demonstrated differential growth patterns between the zebrafish and a close relative the giant danio (Danio aequipinnatus), where the giant danio appears to exhibit indeterminate growth similar to most fish species important for commercial production, while zebrafish exhibit determinate growth more similar to mammalian growth. This study focused on evaluating muscle growth regulation differences in adult zebrafish and giant danio utilizing growth hormone treatment as a mode of growth manipulation. Growth hormone treatment resulted in increased overall growth in giant danio, but failed to increase growth in the zebrafish. Growth hormone treatment increased muscle IGF-I and GHrI gene expression in both species, but to a larger degree in the giant danio. In contrast, zebrafish exhibited a larger increase in IrA and IGF-IrB gene expression in muscle in response to GH treatment. In addition muscle myostatin levels were differentially regulated between the two species, with a down-regulation observed in rapidly growing, GH-treated giant danio and an up-regulation in zebrafish not actively growing in response to GH. This is the first report of differential expression of growth-regulating genes in closely related fish species exhibiting opposing growth paradigms. These results further support the role that the zebrafish and giant danio can play important model organisms for determinate and indeterminate growth.
斑马鱼（Danio rerio）已成为发育生物学和人类健康研究的重要模式生物。我们最近证明了斑马鱼和近亲巨丹鱼（Danio aequipinnatus）之间存在不同的生长模式，其中巨丹鱼似乎表现出不定型生长，类似于大多数对商业生产重要的鱼类物种，而斑马鱼则表现出更类似于哺乳动物生长的定型生长。本研究侧重于利用生长激素处理评估成年斑马鱼和巨丹鱼的肌肉生长调控差异，以此作为生长调控的模式。生长激素处理导致巨丹鱼的整体生长增加，但未能增加斑马鱼的生长。生长激素处理增加了两种鱼类肌肉中 IGF-I 和 GHrI 基因的表达，但在巨丹鱼中表达增加的程度更大。相比之下，斑马鱼对 GH 处理的肌肉中 IrA 和 IGF-IrB 基因的表达有更大的增加。此外，两种鱼类的肌肉中肌肉生长抑制素水平存在差异调节，在快速生长的 GH 处理的巨丹鱼中观察到下调，而在不积极生长的斑马鱼中上调。这是首次报道在表现出相反生长模式的密切相关鱼类物种中，生长调节基因的差异表达。这些结果进一步支持了斑马鱼和巨丹鱼作为定型和不定型生长的重要模式生物的作用。
