Disruption of the mouse gene encoding the gap junction subunit alpha3 connexin 46 (Cx46) results in the formation of lens cataracts. The timing of the onset of this lens opacity is affected by the genetic background, i.e. the mouse strain. To elucidate the mechanism by which cataracts form in the 129Sv/Jae strain earlier than in the C57BL/6J strain, global gene expression was quantitated in the lenses of these strains. Lens cDNAs were analyzed by hybridization to DNA microarrays and with real time-PCR. Theories are proposed based on the observed higher level of expression of the stress-response genes in the C57BL/6J strain and variations in the expression levels of genes involved in protein synthesis, metabolism, catabolism and cell proliferation. How these variations in gene expression might affect the response of lens fiber cells to the increased calcium, caused by lack of alpha3Cx46, is considered. The possibility that the proteins coded by the strain-variable genes might influence the cataract-associated proteolysis of gamma-crystallin is also addressed. Experiment Overall Design: To determine differences in transcript expression between the lenses of two mouse wild type strains (129 SvJae and C57BL/6J), as well as between alpha3Cx46 KO and wild-type mice. The former comparison may lead to identification of potential candidate(s) genes that prevent (or promote) cataract formation, whereas the latter comparison may provide insights into the mechanism by which cataract formation occurs in the alpha3Cx46 KO mice. Total 8 samples were used ( two separate samples for each of the following 4 types of mice: 129SvJae wild type, 129SvJae alpha3Cx46 KO, C57BL/6J wild type and C57BL/6J alpha3Cx46 KO)