This material has been published in Developmental Biology 165(2):432-41, the only definitive repository of the content that has been certified and accepted after peer review. Copyright and all rights therein are retained by Academic Press. This material may not be copied or reposted without explicit permission. Copyright © 1994 by Academic Press)

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Developmental Biology 1994 Oct;165(2):432-41

Cardiac troponin I is a heart-specific marker in the Xenopus embryo: expression
during abnormal heart morphogenesis.

Drysdale TA, Tonissen KF, Patterson KD, Crawford MJ, Krieg PA

Department of Zoology, University of Texas at Austin 78712.

Cardiac troponin I (troponin Ic) expression is restricted to the heart at all
stages of Xenopus development. Whole-mount in situ hybridization and Northern
blot analysis indicates that troponin Ic is first expressed in tailbud embryos
(stage 28) about the time of the first cytological heart differentiation and
about 24 hr before beating tissue is observed. We have used this marker to
examine abnormal heart morphogenesis in embryos treated with retinoic acid and
lithium. When retinoic acid is administered to embryos prior to heart
specification, heart tissue is reduced and often completely ablated. When
embryos are treated after heart specification, but before the heart primordium
migrates to the ventral midline, the migration is unaffected but smaller,
abnormal hearts result. Lithium treatment of cleavage stage embryos causes an
increase in heart tissue. In severely dorsalized embryos, heart tissue can be
found around the entire embryo with the exception of a small gap at the most
dorsal point. This gap indicates that migration of the heart to the ventral
midline does not occur in these embryos. Later in development, a centrally
located, beating heart is observed in dorsalized embryos. The timing of its
appearance suggests that it is formed by movements normally associated with
heart morphogenesis rather than migration.

PMID: 7958411, UI: 95046865