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XB-ART-40353
Dev Biol. December 1, 2009; 336 (1): 20-9.

Absence of heartbeat in the Xenopus tropicalis mutation muzak is caused by a nonsense mutation in cardiac myosin myh6.



Abstract
Mechanisms coupling heart function and cardiac morphogenesis can be accessed in lower vertebrate embryos that can survive to swimming tadpole stages on diffused oxygen. Forward genetic screens in Xenopus tropicalis have identified more than 80 mutations affecting diverse developmental processes, including cardiac morphogenesis and function. In the first positional cloning of a mutation in X. tropicalis, we show that non-contractile hearts in muzak (muz) embryos are caused by a premature stop codon in the cardiac myosin heavy chain gene myh6. The mutation deletes the coiled-coil domain responsible for polymerization into thick filaments, severely disrupting the cardiomyocyte cytoskeleton. Despite the lack of contractile activity and absence of a major structural protein, early stages of cardiac morphogenesis including looping and chamber formation are grossly normal. Muz hearts subsequently develop dilated chambers with compressed endocardium and fail to form identifiable cardiac valves and trabeculae.

PubMed ID: 19769958
PMC ID: PMC2786259
Article link: Dev Biol.
Grant support: 1 RO1 HD4 2276-01 NICHD NIH HHSMedical Research Council , R01 HD042276-01 NICHD NIH HHS , MC_U117560482 Medical Research Council , MC_U117562103 Medical Research Council , R01 HD042276 NICHD NIH HHS , 1 RO1 HD4 2276-01 NICHD NIH HHSMedical Research Council , MC_U117560482 Medical Research Council , MC_U117562103 Medical Research Council , R01 HD042276-01 NICHD NIH HHS , R01 HD042276 NICHD NIH HHS , 1 RO1 HD4 2276-01 NICHD NIH HHSMedical Research Council , MC_U117560482 Medical Research Council , MC_U117562103 Medical Research Council , R01 HD042276-01 NICHD NIH HHS , R01 HD042276 NICHD NIH HHS

Genes referenced: myh15 myh4 myh6 myh7

Antibodies referenced: Myh6 Ab1
Morpholinos referenced: ebf2 MO1 ebf3 MO1 myh6 MO2 myh6 MO3

References:
Armstrong, 2004, Pubmed[+]


Article Images: [+] show captions

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