Mutual Regulation of CRP and N(epsilon)-Lysine Acetylation in Escherichia Coli

Post-translational modifications, such as N(epsilon)-lysine acetylation, are known to alter the behavior of transcriptional regulators in eukaryotes, but very little is known about the consequences of acetylation on transcriptional regulation in bacteria. Here, I provide evidence that a global transcriptional regulator of carbon metabolism, cAMP Receptor Protein (CRP), promotes both enzymatic and non-enzymatic lysine acetylation in E. coli. Non-enzymatic lysine acetylation occurs when cells ferment acetate, such as during growth on high concentrations of glucose. Intriguingly, CRP can be non-enzymatically acetylated on several lysines, including lysine 100 (K100). I provide evidence that neutralization of the K100 positive charge, as would occur upon K100 acetylation, has a dual effect on CRP activity. First, K100 neutralization decreases CRP activity at some Class II promoters. This decreased activity likely results from disruption of the interaction between Activating Region 2 (AR2) of CRP and the RNA polymerase alpha subunit N-terminal domain. Second, K100 neutralization increases the CRP half-life, leading to increased CRP steady state levels. Due to increased steady state levels, CRP activity is increased at some Class I promoters, in which CRP does not require AR2. Taken together, I propose that CRP promotes global acetylation, including CRP K100 acetylation, when cells are grown on glucose by positively regulating non-enzymatic acetylation. A consequence of K100 acetylation may be inverse regulation of Class II and Class I promoters under these conditions. This mechanism may help regulate carbon flux though central metabolism

Tilapia Culture.

2 p

Tilapia Culture.

2 p

Farming Freshwater Shrimp.

4 p

THE ECONOMIC THRESHOLD FOR GRASSHOPPER CONTROL ON PUBLIC RANGELANDS

The U.S. Department of Agriculture's Animal and Plant Health Inspection Service (APHIS) is responsible for controlling grasshopper populations on public rangelands. Under current guidelines, control of grasshoppers on rangeland should occur if grasshopper densities are at least eight per square yard. This article evaluates the concept of an economic threshold relative to the value of forage saved from destruction during a grasshopper outbreak. It is shown that financial justification for treating grasshopper outbreaks depends upon grasshopper density, rangeland productivity, climate factors, livestock cost and return relationships, and the efficacy of treatment options.Resource /Energy Economics and Policy, Land Economics/Use,

Sex, Violence, and Hand Puppets: History and Structure of Punch and Judy Performance Tradition

Punch and Judy are characters who exist only within the boundaries of the puppet theatre, in performances where characters are portrayed by inanimate figures. Nonetheless, the history of the puppet theatre, and particularly that of Punch and Judy, is closely related to the history of more widely accepted, actor-based theatre, where characters are portrayed by human beings. While the two traditions-share many common elements--such as the importance of characterization, direction, and design--the essential difference between actor-theatre and puppetry is the manner in which the performance is presented. The approach of this study is threefold: first, a linear history of the development of Punch and Judy will be presented; secondly, both the internal and external elements that affect the structure of Punch and Judy will be explored; and finally, the power of the puppet theatre that allows the transformation of profane material into that which is considered acceptable will be examined. The exploration of these areas makes possible a more complete vision of the Punch and Judy performance tradition. Furthermore, through a synthesis of the information from these three distinct elements, the ultimate objective of this study can be achieved: an explanation of how these components promoted the development of the Punch and Judy performance tradition

Host-Switching Does not Circumvent the Ni-based Defence of the Ni hyperaccumulator \u3ci\u3eStreptanthus polygaloides\u3c/i\u3e (Brassicaceae)

Elevated tissue concentrations of metals have been shown to defend metal-hyperaccumulating plants against both herbivores and pathogens. Tolerance of metal-based defences presents a challenge to herbivores, because heavy metals cannot be degraded or metabolized. One strategy that herbivores can employ to counter high-metal defences is dietary dilution, or host switching. Highly mobile herbivores are most likely to use this strategy, but less mobile lepidopteran larvae can also Improve their performance on toxic hosts if early instar development occurs on more favourable hosts. We examined the effects of host switching on growth and survival of a generalist folivore. Specifically, we tested the hypothesis that early larval development on non-toxic hosts could improve larval performance of the beet armyworm, Spodoptera exigua, an high-Ni Streptanthus polygaloides, a Ni hyperaccumulator. Initial larval performance (weight gain) was lowest for insects switched to high-N! hosts. Decreased initial larval performance was also noted for insects switched from lettuce to low-Ni S. polygaloides, but these larvae recovered quickly. Original host identity (lettuce or low-Ni S. polygaloides) did not affect subsequent larval performance. By day 8 of the feeding trials, all larvae switched to high-Ni hosts had died. We conclude that polyphagous Spodoptera larvae are unable to counter NI-based defences via host switching