Literature

Evidence showing the limitations of genetic reductionism continues to be published. The latest involves the development of the mammalian heart. Using the mouse as a model system, the researchers noted that the early stage heart reveals symmetrical development of the branchial arch arteries. In the space of just one day, these arch arteries are remodelled so that blood flows predominantly through the left arch arteries. Previous work had identified the likely role of a transcription factor Pitx2 and a signalling molecule Nodal, but "the overall mechanisms - or genetic pathways - that govern asymmetric development of the artery arches remained elusive."
Apparently, evidence has been accumulating "to suggest that the mechanical force created by blood flow affects gene expression in the developing embryo" and it is this hypothesis that has stimulated the reported research. In essence, (1) the transcription factor Pitx2 induces morphological change to the outflow tract of the heart, (2) the blood flow becomes asymmetric, (3) the uneven blood flow triggers a signalling response - (4) resulting in the asymmetric remodelling of the great arteries.
This cascade of cause and effect involves a remarkable collaboration between genetics and haemodynamics. According to the accompanying News & Views essay, the researchers' results "provide a useful model for converting physical forces into genetic information - that is, the maintenance by haemodynamics of the expression of vessel-stabilization factors that shape the asymmetrical cardiovascular system of mammals."
As is often the case when faced with complex specified systems like this, academic writers resort to anthropomorphic language. Nature is portrayed as the creator and even the artist:

"Compared with the masterpiece crafted by nature, even Leonardo da Vinci's anatomical drawings of the cardiovascular system seem primitive. In creating this system, nature seems to use blood flow as its paintbrush."

These writers are recognising that there is a richness before them that needs expression. It is a richness that they know cannot be captured by talking about evolutionary "tinkering" (which is what their naturalistic evolutionary worldview demands). What they need is a worldview that allows design to be the product of an intelligent agent. They need to allow the paintbrush to be held by a real artist. This is what Intelligent Design offers.

Haemodynamics determined by a genetic programme govern asymmetric development of the aortic arch
Kenta Yashiro, Hidetaka Shiratori & Hiroshi Hamada
Nature 450, 285-288 (8 November 2007) | doi:10.1038/nature06254

Abstract: [. . .] The cellular and molecular bases of asymmetric morphogenesis remain largely unknown, however. Here we show that ablation of unilateral Pitx2 expression in mice impairs asymmetric remodelling of the branchial arch artery (BAA) system, resulting in randomized laterality of the aortic arch. Pitx2-positive cells were found not to contribute to asymmetrically remodelled arteries. Instead, Pitx2 functions in the secondary heart field5 and induces a dynamic morphological change in the outflow tract of the heart, which results in the provision of an asymmetric blood supply to the sixth BAA. This uneven distribution of blood flow results in differential signalling by both the platelet-derived growth factor receptor and vascular endothelial growth factor receptor 2. The consequent stabilization of the left sixth BAA and regression of its right counterpart underlie left-sided formation of the aortic arch. Our results therefore indicate that haemodynamics, generated by a Pitx2-induced morphological change in the outflow tract, is responsible for the asymmetric remodelling of the great arteries.

See also:

Snider, P. & Conway, S.J. The power of blood, Nature 450, 180-181 (8 November 2007) | doi:10.1038/450180a