Connexin36, an essential element in the rod pathway, is highly expressed in the essentially rodless retina of Gallus gallus

Abstract

Electrical coupling provided by connexins (Cx) in gap junctions (GJ) plays important roles in both the developing and the mature retina. In mammalian nocturnal species, Cx36 is an essential component in the rod pathway, the retinal circuit specialized for night, scotopic vision. Here, we report the expression of Cx36 in a species (Gallus gallus) that phylogenetic development endows with an essentially rodless retina. Cx36 gene is very highly expressed in comparison with other Cxs previously described in the adult retina, such as Cx43, Cx45, and Cx50. Moreover, real-time PCR, Western blot, and immunofluorescence all revealed that Cx36 expression massively increased over time during development. We thoroughly examined Cx36 in the inner and outer plexiform layers, where this protein was particularly abundant. Cx36 was observed mainly in the off sublamina of the inner plexiform layer rather than in the on sublamina previously described in the mammalian retina. In addition, Cx36 colocalized with specific cell markers, revealing the expression of this protein in distinct amacrine cells. To investigate further the involvement of Cx36 in visual processing, we examined its functional regulation in retinas from dark-adapted animals. Light deprivation markedly up-regulates Cx36 gene expression in the retina, resulting in an increased accumulation of the protein within and between cone synaptic terminals. In summary, the developmental regulation of Cx36 expression results in particular circuitry-related roles in the chick retina. Moreover, this study demonstrated that Cx36 onto- and phylogenesis in the vertebrate retina simultaneously exhibit similarities and particularities.

Scaling behavior in probabilistic neuronal cellular automata

“…We also developed a mean-field model for the dynamics, and show that at the critical point the numerical results are in good agreement with the theoretical predictions, and further, with the exponents obtained for branching processes [45,46]. The KC model established a theoretical framework for the optimization of dynamical range at criticality, and this has been subsequently verified experimentally [47,48]. It would also be of interest to see if optimization of susceptibility can also be demonstrated experimentally in such models.…”

Statistical physics approach to dendritic computation: The excitable-wave mean-field approximation

“…This signal compression property, or enhancement of dynamic range, is a general property of excitable media and has proven very robust against variations in the topology of the medium and the level of modeling, from cellular automata to compartmental conductance-based models [21][22][23][24][25][26][27][28][29][30][31][32][33]. Furthermore, the idea that dynamic range can be enhanced in neuronal excitable media has received support from experiments in very different setups [34,35], which again suggests that the phenomenon is robust.…”

Ontogênese de conexinas no cerebelo.

“…Neurônios de muitas regiões do SNC de mamíferos e na retina de outras espécies de vertebrados apresentam Cx36 Kihara et al, 2009;O'Brien et al, 1996;O'Brien et al, 1998). A Cx36 encontra-se ainda nas células beta do pâncreas, células cromafins da adrenal e em outras células que, assim como o sistema nervoso, apresentam origem ectodérmica (Condorelli et al, 1998).…”

“…O aumento da expressão de Cx36 ao longo do desenvolvimento foi observado também na retina de galinha (Kihara et al, 2009), na retina de camundongos (Kihara et al, 2006) e em diferentes regiões do SNC de ratos Condorelli et al, 2000). No diencéfalo, hipocampo e córtex cerebral, a expressão de Cx36 aumenta durante as suas primeiras semanas pós-natais, diminuindo subsequentemente .…”

“…No sistema nervoso da galinha, a Cx36 foi descrita apenas na retina (Kihara et al, 2009). No córtex cerebelar de ratos, o RNAm da Cx36 foi observado principalmente no terço inferior da ML, provavelmente em células em cesto, e nas células de Golgi da GL Condorelli et al, 2000).…”