To grow or not to grow: nutritional control of development during Caenorhabditis elegans L1 arrest.

It is widely appreciated that larvae of the nematode Caenorhabditis elegans arrest development by forming dauer larvae in response to multiple unfavorable environmental conditions. C. elegans larvae can also reversibly arrest development earlier, during the first larval stage (L1), in response to starvation. "L1 arrest" (also known as "L1 diapause") occurs without morphological modification but is accompanied by increased stress resistance. Caloric restriction and periodic fasting can extend adult lifespan, and developmental models are critical to understanding how the animal is buffered from fluctuations in nutrient availability, impacting lifespan. L1 arrest provides an opportunity to study nutritional control of development. Given its relevance to aging, diabetes, obesity and cancer, interest in L1 arrest is increasing, and signaling pathways and gene regulatory mechanisms controlling arrest and recovery have been characterized. Insulin-like signaling is a critical regulator, and it is modified by and acts through microRNAs. DAF-18/PTEN, AMP-activated kinase and fatty acid biosynthesis are also involved. The nervous system, epidermis, and intestine contribute systemically to regulation of arrest, but cell-autonomous signaling likely contributes to regulation in the germline. A relatively small number of genes affecting starvation survival during L1 arrest are known, and many of them also affect adult lifespan, reflecting a common genetic basis ripe for exploration. mRNA expression is well characterized during arrest, recovery, and normal L1 development, providing a metazoan model for nutritional control of gene expression. In particular, post-recruitment regulation of RNA polymerase II is under nutritional control, potentially contributing to a rapid and coordinated response to feeding. The phenomenology of L1 arrest will be reviewed, as well as regulation of developmental arrest and starvation survival by various signaling pathways and gene regulatory mechanisms.

Rhetoric, Roman Values, and the Fall of the Republic in Cicero's Reception of Plato

This dissertation seeks to identify what makes Cicero’s approach to politics unique. The author's methodology is to turn to Cicero’s unique interpretation of Plato as the crux of what made his thinking neither Stoic nor Aristotelian nor even Platonic (at least, in the usual sense of the word) but Ciceronian. As the author demonstrates in his reading of Cicero’s correspondences and dialogues during the downward spiral of a decade that ended in the fall of the Republic (that is, from Cicero’s return from exile in 57 BC to Caesar’s crossing of the Rubicon in 49 BC), it is through Cicero's reading of Plato that the former develops his characteristically Ciceronian approach to politics—that is, his appreciation for the tension between the political ideal on the one hand and the reality of human nature on the other as well as the need for rhetoric to fuse a practicable compromise between the two. This triangulation of political ideal, human nature, and rhetoric is developed by Cicero through his dialogues "de Oratore," "de Re publica," and "de Legibus."