The retina is a highly ordered laminar structure, comprising three
compact layers of neurons separated by two synaptic layers, which has
proven a valuable model to study gap junctions and cell specific
expression patterns of connexins in neuronal tissues. Visual processing
in the retina information is partly accomplished by laterally orientated
horizontal cells. Two connexins, Cx52.6 and Cx55.5 has been shown to be
expressed in zebrafish horizontal cells. Sequence analysis of zfCx55.5
and zfCx52.6 has revealed only limited homology of these connexins to
other connexins from fish and higher vertebrates. ZfCx52.6 shows around
57% amino-acid homology with zfCx55.5, where as the zfCx55.5 has been
shown to share about 50% homology with the mouse Cx57. Both of these
connexins have been found to show highly restricted expression in the
horizontal cells of zebrafish retina. The molecular mechanism
responsible for their cell specific expression are unveiled in this
dissertation. Moreover, connexins perform various functions for which
gap-junction communication seems to be dispensable. With reference to
Cx55.5, we propose a mechanism which can endow the connexins with the
ability to perform