Independent evolution of striated muscles in cnidarians and bilaterians

摘要: Striated muscles are present in bilaterian animals (for example, vertebrates, insects and annelids) some non-bilaterian eumetazoans (that is, cnidarians ctenophores). The considerable ultrastructural similarity of striated between these animal groups is thought to reflect a common evolutionary origin. Here we show that muscle protein core set, including type II myosin heavy chain (MyHC) motor characteristic was already unicellular organisms before the origin multicellular animals. Furthermore, 'striated muscle' 'non-muscle' myhc orthologues expressed differentially two sponges, compatible with functional diversification true subsequent use MyHC fast-contracting smooth muscle. Cnidarians ctenophores possess but lack crucial components muscles, such as genes code for titin troponin complex, suggesting convergent evolution muscles. Consistently, jellyfish shared set Z-disc proteins not associated instead elsewhere or ubiquitously. independent eumetazoan through addition new pre-existing, ancestral contractile apparatus may serve model complex cell types.