Zhang C, Pietras K M, Sferrazza G F, Jia P, Athauda G, Rueda-de-Leon E, Maier J A, Dube D K, Lemanski S L, Lemanski L F
Department of Biomedical Science, Florida Atlantic University, Boca Raton, Florida 33431, USA.
J Cell Biochem. 2007 Jan 1;100(1):1-15. doi: 10.1002/jcb.20918.
The Mexican axolotl, Ambystoma mexicanum, is an excellent animal model for studying heart development because it carries a naturally occurring recessive genetic mutation, designated gene c, for cardiac nonfunction. The double recessive mutants (c/c) fail to form organized myofibrils in the cardiac myoblasts resulting in hearts that fail to beat. Tropomyosin expression patterns have been studied in detail and show dramatically decreased expression in the hearts of homozygous mutant embryos. Because of the direct interaction between tropomyosin and troponin T (TnT), and the crucial functions of TnT in the regulation of striated muscle contraction, we have expanded our studies on this animal model to characterize the expression of the TnT gene in cardiac muscle throughout normal axolotl development as well as in mutant axolotls. In addition, we have succeeded in cloning the full-length cardiac troponin T (cTnT) cDNA from axolotl hearts. Confocal microscopy has shown a substantial, but reduced, expression of TnT protein in the mutant hearts when compared to normal during embryonic development.
墨西哥钝口螈（Ambystoma mexicanum）是研究心脏发育的优良动物模型，因为它携带一种自然发生的隐性基因突变，即导致心脏无功能的基因c。双隐性突变体（c/c）在心肌成肌细胞中无法形成有组织的肌原纤维，导致心脏无法跳动。原肌球蛋白的表达模式已得到详细研究，结果显示在纯合突变胚胎的心脏中其表达显著降低。由于原肌球蛋白与肌钙蛋白T（TnT）之间存在直接相互作用，且TnT在横纹肌收缩调节中具有关键功能，我们将对该动物模型的研究扩展到了对正常墨西哥钝口螈发育过程以及突变体中TnT基因在心肌中的表达特征进行研究。此外，我们成功地从墨西哥钝口螈心脏中克隆出了全长心脏肌钙蛋白T（cTnT）cDNA。共聚焦显微镜检查显示，与正常胚胎发育期间相比，突变体心脏中TnT蛋白的表达量虽有显著降低，但仍有表达。
