Metazoan evolution

Tubulins arose very early during the course of evolution of unicellular eukaryotes and provide the machinery for the equipartitioning of chromosomes in mitosis, cell locomotion, and the maintenance of cell shape. The primordial genes that coded for tubulins likely were few in number. As metazoan evolution progressed, natural selection processes conserved multiple and mutant tubulin genes in response to the requirements for differentiated cell types (Sullivan, 1988). 

Miklos, G. L. G (1993) Emergence of Organizational Complexities During Metazoan Evolution Perspectives from Molecular Biology, Paleontology and Neo-Darwinism, Memoirs of the Association of Australasian Paleontologists, 15, 28. 

The Cambrian explosion, on the other hand, had its roots precisely in the developing strategies of Cambrian embryos, and as long as the logic of development remains a mystery, we have no chance of understanding what happened. And we have also little chance of understanding the rest of metazoan evolution, because animals are, first of all, what their embryos make of them. 

Clark, R.B. (1964). Dynamics in Metazoan Evolution The Origin of the Coelom and Segments. Clarendon Press, Oxford. 

The mitochondrial control of cell fate in vertebrates involves interactions among proteins of the B cell lymphoma-2 (Bcl-2) proto-oncogene family, which has been functionally conserved throughout metazoan evolution. Its involvement in programmed cell death was first described in Caenorhabditis elegans, where it was shown that expression of ced-4 was required for cell death activation, whereas ced-9 overexpression maintained cell viability by suppressing interactions between the products of ced-4 and downstream cell death executioner proteins109. 

Hendriks L, Huysmans E, Vandenberghe A, De Wachter R (1986) Primary structures of the 5S ribosomd RNAs of 11 arthropods and applicability of 5S RNA to the study of metazoan evolution. J Mol Evol 24 103-109... 

Bipalium kewense 51) suggests that urea biosynthesis arose very early in metazoan evolution. 

Hahn ME, Karchner SI (2012) Structural and functional diversification of AhRs during metazoan evolution. In Pohjanvirta R (ed) The AH receptor in biology and toxicology. Willey New York, pp 389-403... 

Adoutte, A. and Philippe, H. (1993) The major lines of metazoan evolution summary of traditional evidence and lessons from ribosomal RNA sequence analysis. In Pichon (ed.) Comparative Molecular Neurobiology (Basel Birkhauser), pp. 1-30. 

Conway Morris, S. (1998) Early metazoan evolution reconciling paleontology and molecular biology , American Zoologist, 38, 867-77. 

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