Changes of telomere length cause reciprocal changes in the lifespan of mother cells in Saccharomyces cerevisiae

Budding yeast cells divide asymmetrically, giving rise to a mother and its daughter. Mother cells have a limited division potential, called their lifespan, which ends in proliferation-arrest and lysis. In this report we mutate telomerase in Saccharomyces cerevisiae to shorten telomeres and show that, rather than shortening lifespan, this leads to a significant extension in lifespan. This extension requires the product of the SIR3 gene, an essential component of the silencing machinery which binds to telomeres. In contrast, longer telomeres in a genotypically wild-type strain lead to a decrease in lifespan. These findings suggest that the length of telomeres dictates the lifespan by regulating the amount of the silencing machinery available to nontelomeric locations in the yeast genome

The Saccharomyces SUN gene, UTH1, is involved in cell wall biogenesis

Deletion of the Saccharomyces gene, UTH1, a founding member of the SUN family of fungal genes, has pleiotropic effects. Several phenotypes of Δuth1 cells including their decreased levels of mitochondrial proteins, their impaired autophagic degradation of mitochondria, and their increased viability in the presence of mammalian BAX, a proapoptotic regulator localized to the mitochondria, have prompted others to propose that the Uth1p functions primarily at the mitochondria. In this report, we show that cells lacking UTH1 have more robust cell walls with higher levels of β-d-glucan that allows them to grow in the presence of calcofluor white or sodium dodecyl sulfate, two reagents known to perturb the yeast cell wall. Moreover, these Δuth1 cells are also significantly more resistant to spheroplast formation induced by zymolyase treatment than their wild-type counterparts. Surprisingly, our data suggest that several of the enhanced growth phenotypes of Δuth1 cells, including their resistance to BAX-mediated toxicity, arise from a strengthened cell wall. Therefore, we propose that Uth1p\u27s role at the cell wall and not at the mitochondria may better explain many of its effects on yeast physiology and programmed cell death

Catholic Bioethics after Beatitude and Biomedicine: A Response to My Colleagues

The article presents the author\u27s views on Catholic bioethics, highlighting the comments that he received from his colleagues on his book Biomedicine and Beatittude: An Introduction to Catholic Bioethics. He examines three areas of engagement for Catholic bioethicists which are science, technology, and society as well as the moral engagement with modern medicine and related technologies. He also explores Pope Francis\u27 pastoral strategy which involves joy, mercy, and poverty