Cardiovascular development: towards biomedical applicability

Abstract

Research in animal models established that tinman, a key gene in Drosophila dorsal vessel development, is an orthologue of Nkx2-5, a key gene in vertebrate cardiac development. Similarities between the arthropod dorsal vessel and vertebrate hearts are interpreted in light of concepts such as homology or convergence. We discuss this controversy in the context of the evolution of animal circulatory pumps and propose the distinction between peristaltic and chambered pumps as a fundamental parameter for evolutionary comparisons between bilaterian pumps. Neither homology nor convergence is satisfactory to explain the origins of hearts and pumping organs. Instead, we propose that animal pumps derive from parallel improvements of an ancestral, peristaltic design represented by a layer of myocytes at the external walls of primitive vessels. This paradigm unifies disparate views, impacts our understanding of bilaterian evolution and may be helpful to interpret similarities between pumping organs of phylogenetically relevant species and emerging models.

Developmental Bias and Evolution: A Regulatory Network Perspective

“…The potential macroevolutionary significance of developmental bias is further exemplified by hundreds of examples of repeated co-option and recruitment of the same developmental pathways into the building of analogous structures and organs in otherwise unrelated organisms [reviewed in Shubin et al (2009) and Held (2017)]. Some of the most spectacular cases include the independent evolution of eyes across phyla (Mercader et al 1999;Kozmik 2005;Kozmik et al 2008), the evolution or contractile hearts in vertebrates and invertebrates (Olson 2006;Xavier-Neto et al 2007), or the formation of outgrowths from insect legs to echinoderm tube feet or ascidian siphons (Panganiban et al 1997;Mercader et al 1999); in each set of cases the same set of preexisting genes, pathways, and morphogenetic processes was used to arrive at functionally highly similar outcomes. Rather than reflecting constraint, such cases are consistent with developmental systems shaping evolutionary trajectories by generating opportunities to evolve complex structures repeatedly, reliably and regardless of taxonomic context.…”

Mechanical regulation of cardiac development

“…These traveling mechanical waves were traditionally considered myocardial peristaltic waves (Xavier-Neto et al, 2007) and tubular embryonic heart was accepted to work like a technical roller peristaltic pump (Manner et al, 2010). Experiments on zebrafish embryos offer an alternative theory (Forouhar et al, 2006): (I) While peak flow velocity generated by a roller peristaltic pump corresponds to the speed of a compression wave, peak ventricular inflow velocity of an embryonic zebrafish heart recorded exceeds the speed of a traveling contraction wave.…”

Signaling through retinoic acid receptors in cardiac development: Doing the right things at the right times

“…This is because, in contrast to other chordates such as tunicates and cephalochordates, vertebrates evolved a peculiar model of circulatory system in which circulatory work is centralized in the chambered heart, which is a highly efficient pump [12]. This chambered configuration is so special that apparently only one other group of animals, the mollusks, adopted a similar design for its circulatory pumps [13, 14]. Moreover, it is only fair to say that research on vertebrate cardiovascular development has progressed to a point in which the major players have been identified and the major interactions between them have at least been sketched, a state of affairs, perhaps, second only to research on the developing spinal cord [15, 16].…”