"Being able to group different kinds of organisms together into larger groups is nice, but how they're connected at the very early stages of cellular evolution is still very problematic," says Gray. "The idea of how organisms and their cells evolve is still a big burning question".
What makes the endosymbiosis in trypanosomatids a special model to study cellular evolution is the fact that each protozoan contains only one symbiotic bacterium, indicating that the host imposes tight control over the endosymbiont division.
It was not explained how nitrogen fixation and extensive cellular evolution was possible in the absence of photosynthesis, but implied that ecosystems may originally have been based on methanogenesis.
One issue that we have with Woese's view of early cellular evolution is that he does not clearly distinguish between two different phenomena that would occur if the HGT rate were very large: the loss of coherence of the species and the loss of coherence of the genome.
Cellular differentiation and evolution are stochastic processes that can involve multiple types (or states) of particles moving on a complex, high-dimensional state-space or "fitness" landscape.
Specifically, somatic cellular selection and evolution are the fundamental processes leading to malignancy, metastasis, and resistance to therapies, with the contribution of cancer stem cells as the progenitors of these more differentiated cell types (Shipitsin and Polyak 2008; Greaves this volume).
As presented by Dr. François Fuks (Free University of Brussels, Belgium), cellular transformation and malignant evolution are connected to gene expression and silencing mediated by epigenetics perturbations, such as histone modifications and DNA methylation mediated by DNA methyltransferases, thus leading to aberrant chromatin dynamic.
Claims that viruses are alive and predate cellular evolution can be understood only within the framework of a strict geneticist view of life based exclusively on the property of evolution and using the definition of the term "virus" as a relaxed metaphor for self-replicating entities something which viruses, strictly speaking, are not.
The Periodic charts could be considered as a reliable and refreshable platform through which the cellular evolution could be patterned and characterized.
Given that this is such a diverse protein family spanning essentially the whole history of cellular evolution, there is some uncertainty here, but one thing about their reconstructed phylogeny really leapt out at me.
