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Chamber identity programs drive early functional partitioning of the heart.

Nature communications (2015-08-27)
Christian Mosimann, Daniela Panáková, Andreas A Werdich, Gabriel Musso, Alexa Burger, Katy L Lawson, Logan A Carr, Kathleen R Nevis, M Khaled Sabeh, Yi Zhou, Alan J Davidson, Anthony DiBiase, Caroline E Burns, C Geoffrey Burns, Calum A MacRae, Leonard I Zon
ABSTRACT

The vertebrate heart muscle (myocardium) develops from the first heart field (FHF) and expands by adding second heart field (SHF) cells. While both lineages exist already in teleosts, the primordial contributions of FHF and SHF to heart structure and function remain incompletely understood. Here we delineate the functional contribution of the FHF and SHF to the zebrafish heart using the cis-regulatory elements of the draculin (drl) gene. The drl reporters initially delineate the lateral plate mesoderm, including heart progenitors. Subsequent myocardial drl reporter expression restricts to FHF descendants. We harnessed this unique feature to uncover that loss of tbx5a and pitx2 affect relative FHF versus SHF contributions to the heart. High-resolution physiology reveals distinctive electrical properties of each heart field territory that define a functional boundary within the single zebrafish ventricle. Our data establish that the transcriptional program driving cardiac septation regulates physiologic ventricle partitioning, which successively provides mechanical advantages of sequential contraction.

MATERIALS
Product Number
Brand
Product Description

Sigma-Aldrich
Propidium iodide, ≥94.0% (HPLC)
Sigma-Aldrich
4-Hydroxytamoxifen, ≥70% Z isomer (remainder primarily E-isomer)
Sigma-Aldrich
Propidium iodide solution, solution (1.0 mg/ml in water)
Sigma-Aldrich
Anti-GFP, N-terminal antibody produced in rabbit, ~1.0 mg/mL, affinity isolated antibody, buffered aqueous solution
Sigma-Aldrich
Allyl methyl sulfone, 96%