Complex sentence: The main target genes of PNR are rhodopsin and several opsins and the proteins encoded by these genes are essential for sight and consequently PNR is essential for the proper development of the retina.
Split into simpler sentences: The main target genes of PNR are rhodopsin and several opsins and the proteins encoded by these genes are essential for sight. Consequently PNR is essential for the proper development of the retina.