Nature Reviews Neuroscience 10, 701-712
(October 2009) | doi:10.1038/nrn2717
The origin and evolution of synapses
Proteomic studies of the molecular components of the highly complex mammalian postsynaptic machinery point to an ancestral molecular machinery in unicellular organisms— the protosynapse — that existed before the evolution of metazoans and neurons, and h ence challenges existing views on the origins of the brain.
It is conceivable that the first protein–protein interaction that led to synaptogenesis would be homophilic,… We postulate that these molecules originated before the evolution of synapses… Cadherins may therefore be important for cytoskeletal rearrangement in choanoflagellates and may represent a precursor to synapse formation… heterophilic transynaptic protein interactions probably evolved later. [p. 703]… implying that they may form a protosynaptic complex involved in sensing environmental stimuli and that they could represent an evolutionary precursor to synaptic sites. [p. 704]
In general terms, the evolution of synaptic genes at the eukaryote–metazoan and metazoan–chordate boundaries preceded their expression in different populations of neurons and synapses and thereby allowed diversity of function in nervous systems that have emerged later, in evolutionary terms, and that are generally larger. [p. 709]
If we can deduce the composition of the last common ancestor of all synapses, the ursynapse, then we should be in a position to address the question of how and why the first synapse originated.
We approach the question of the composition of the ursynapse by taking synaptic proteins identified in vertebrate model organisms and searching for orthologues in the genomes of two categories of organism. [p. 702]
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Gente, com uma linguagem assim condicional dedutiva, fica realmente difícil aceitar o fato, Fato, FATO da evolução como verdade científica devidamente estabelecida assim com a lei da gravidade, assim como a Terra gira em redor do Sol.
Acho que já chegou a hora da Nomenklatura científica encarar o fato como ele realmente é: Darwin não fecha as contas no contexto de justificação teórica desde 1859. Darwin, KAPUT! e eu penso que nem a SÍNTESE EVOLUTIVA AMPLIADA irá salvar o guru de Down, o homem que teve a maior ideia que a humanidade já teve, só que nunca corroborada...
Eu? Eu já disse adeus a Darwin em 1998. Sem medo de ser feliz!!!
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Agradecimentos ao Prof. Dr. Marcos Nogueira Eberlin, da Unicamp, que enviou esta pérola de artigo científico.
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Agradecimentos ao Prof. Dr. Marcos Nogueira Eberlin, da Unicamp, que enviou esta pérola de artigo científico.