Emergence of structure in mouse embryos: Structural Entropy morphometry applied to digital models of embryonic anatomy

A mathematical model of development shows that cell division, short-range signaling and self-activating gene networks increase developmental noise while long-range signaling and epithelial stiffness reduce it

The position of cells during development is constantly subject to noise, i.e. cell-level noise. We do not yet fully understand how cell-level noise coming from processes such as cell division or movement leads to morphological noise, i.e. morphological differences between genetically identical individuals developing in the same environment. To address this question we constructed a large ensemble of random genetic networks regulating cell behaviors (contraction, adhesion, etc.) and cell signaling. We simulated them with a general computational model of development, EmbryoMaker. We identified and studied the dynamics, under cell-level noise, of those networks that lead to the development of animal-like morphologies from simple blastula-like initial conditions. We found that growth by cell division is a major contributor to morphological noise. Self-activating gene network loops also amplified cell-level noise into morphological noise while long-range signaling and epithelial stiffness tended to reduce morphological noise.

Exploring standards for multicellular mammalian synthetic biology

Synthetic biology is moving towards bioengineering multicellular mammalian systems that are poised to advance tissue engineering, biomedicine, and the food industry. Despite progress, the field lacks a framework of standards that could greatly accelerate further development. Here, we explore the landscape of standards for multicellular mammalian synthetic biology. We discuss the limits of current technical standards and categorise unaddressed parameters into an abstraction hierarchy. We then define the concept of a 'synthetic multicellular mammalian system' and apply our standard hierarchy framework to illustrate how it could aid bioengineering endeavours. We conclude with promising areas that could shape the future of the field, flagging the need for a critical and holistic consideration of standards that requires cross-disciplinary dialogue.

The Ground Zero of Organismal Life and Aging

Cells may naturally proceed or be forced to transition to a state with a radically lower biological age, that is, be rejuvenated. Examples are the conversion of somatic cells to induced pluripotent stem cells and rejuvenation of the germline with each generation. We posit that these processes converge to the same 'ground zero', the mid-embryonic state characterized by the lowest biological age where both organismal life and aging begin. It may also be related to the phylotypic state. The ground zero model clarifies the relationship between aging, development, rejuvenation, and de-differentiation, which are distinct throughout life. By extending the rejuvenation phase during early embryogenesis and editing the genome, it may be possible to achieve the biological age at the ground zero lower than that achieved naturally.