Asexual development is increased in XXXX cat-3-null mutant strains.

@entity1980 @entity1104 @entity274 @entity20072
We use asexual development of @entity1980 as a model system with which to determine the causes of cell differentiation. Air exposure of a mycelial mat induces @entity1104 , and adherent hyphae grow aerial hyphae that, in turn, form conidia. Previous work indicated the development of a hyperoxidant state at the start of these morphogenetic transitions and a large increase in catalase activity during conidiation. Catalase 3 (CAT-3) increases at the end of exponential growth and is induced by different stress conditions. Here we analyzed the effects of cat-3-null strains on growth and asexual development. The lack of CAT-3 was not compensated by other catalases, even under oxidative stress conditions, and cat-3(RIP) colonies were sensitive to @entity274 , indicating that wild-type (Wt) resistance to external @entity274 was due to CAT-3. cat-3(RIP) colonies grown in the dark produced high levels of @entity20072 as a consequence of oxidative stress. Light exacerbated oxidative stress and further increased carotene synthesis. In the cat-3(RIP) mutant strain, increased aeration in liquid cultures led to increased @entity1104 and protein oxidation. Compared to the Wt, the cat-3(RIP) mutant strain produced six times more aerial hyphae and conidia in air-exposed mycelial mats, as a result of longer and more densely packed aerial hyphae. Protein oxidation in colonies was threefold higher and showed more aerial hyphae and conidia in mutant strains than did the Wt. Results indicate that oxidative stress due to lack of CAT-3 induces carotene synthesis, @entity1104 , and more aerial hyphae and conidia.
