Stronger Partnerships for Safer Food: An Agenda for Strengthening State and Local Roles in the Nation's Food Safety System

Examines federal, state, and local agencies' responsibilities, strengths, and weaknesses in ensuring food safety. Recommends systemwide reforms to enhance state and local roles and improve surveillance, outbreak response, and regulation and inspection

Effects of CO2-induced pH reduction on the exoskeleton structure and biophotonic properties of the shrimp Lysmata californica.

The anticipated effects of CO2-induced ocean acidification on marine calcifiers are generally negative, and include dissolution of calcified elements and reduced calcification rates. Such negative effects are not typical of crustaceans for which comparatively little ocean acidification research has been conducted. Crustaceans, however, depend on their calcified exoskeleton for many critical functions. Here, we conducted a short-term study on a common caridean shrimp, Lysmata californica, to determine the effect of CO2-driven reduction in seawater pH on exoskeleton growth, structure, and mineralization and animal cryptic coloration. Shrimp exposed to ambient (7.99 ± 0.04) and reduced pH (7.53 ± 0.06) for 21 days showed no differences in exoskeleton growth (percent increase in carapace length), but the calcium weight percent of their cuticle increased significantly in reduced pH conditions, resulting in a greater Ca:Mg ratio. Cuticle thickness did not change, indicating an increase in the mineral to matrix ratio, which may have mechanical consequences for exoskeleton function. Furthermore, there was a 5-fold decrease in animal transparency, but no change in overall shrimp coloration (red). These results suggest that even short-term exposure to CO2-induced pH reduction can significantly affect exoskeleton mineralization and shrimp biophotonics, with potential impacts on crypsis, physical defense, and predator avoidance

The action mechanism of daptomycin

The final publication is available at Elsevier via http://dx.doi.org/10.1016/j.bmc.2016.05.052 © 2016.Daptomycin is a lipopeptide antibiotic produced by the soil bacterium Streptomyces roseosporus that is clinically used to treat severe infections with Gram-positive bacteria. In this review, we discuss the mode of action of this important antibiotic. Although daptomycin is structurally related to amphomycin and similar lipopeptides that inhibit peptidoglycan biosynthesis, experimental studies have not produced clear evidence that daptomycin shares their action mechanism. Instead, the best characterized effect of daptomycin is the permeabilization and depolarization of the bacterial cell membrane. This activity, which can account for daptomycin's bactericidal effect, correlates with the level of phosphatidylglycerol (PG) in the membrane. Accordingly, reduced synthesis of PG or its increased conversion to lysyl-PG promotes bacterial resistance to daptomycin. While other resistance mechanisms suggest that daptomycin may indeed directly interfere with cell wall synthesis or cell division, such effects still await direct experimental confirmation. Daptomycin's complex structure and biosynthesis have hampered the analysis of its structure activity relationships. Novel methods of total synthesis, including a recent one that is carried out entirely on a solid phase, will enable a more thorough and systematic exploration of the sequence space

Fundamental constraints on particle tracking with optical tweezers

A general quantum limit to the sensitivity of particle position measurements is derived following the simple principle of the Heisenberg microscope. The value of this limit is calculated for particles in the Rayleigh and Mie scattering regimes, and with parameters which are relevant to optical tweezers experiments. The minimum power required to observe the zero-point motion of a levitating bead is also calculated, with the optimal particle diameter always smaller than the wavelength. We show that recent optical tweezers experiments are within two orders of magnitude of quantum limited sensitivity, suggesting that quantum optical resources may soon play an important role in high sensitivity tracking applications

China’s Assertive Behavior – Part Two: The Maritime Periphery

In CLM 32, we examined how both Chinese and outside observers look at China’s growing assertiveness on the international stage, that is, the purely perceptual dimensions of the issue. In CLM 34, we assessed whether, to what extent, and in what manner the Chinese government is becoming more assertive in defining and promoting the concept of “core interests.

State-level corruption scandals do little to change voters’ minds about political parties.

Political corruption scandals seem to have become commonplace in American politics and the state-level is no exception. But do such scandals hurt the affected party at the ballot box? In new research which examines the effects of corruption scandals in North Carolina, Michael D. Cobb and Andrew J. Taylor find that voters are generally unable to identify the scandalous politician or their party. They argue that corruption scandals do little to affect a party’s vote, and that citizens tend to base their voting choices on other matters