The King of Rockingham County and the Original Bridge to Nowhere

This chapter, reveals the story -- the clash of personalities, the economic tensions, and the political significance -- behind Rockingham County v. Luten Bridge Co. Since its publication in 1929, the opinion has proceeded to leave an impression on generations of law students. Luten Bridge, a staple in most contracts casebooks, is known today as the paradigmatic case that demonstrates the duty to mitigate damages in contract law, whereby a nonbreaching party is not compensated for performance that occurs after the other party announces an intention to breach. This chapter takes on three objectives: it identifies the case\u27s original importance, uncovers the opinion\u27s political and jurisprudential significance, and tells a remarkable story, one that arose within a heated tax revolt pitting the county\u27s farmers against its most celebrated industrialist. Much more than a crisp illustration of the duty to mitigate, Rockingham County v. The Luten Bridge Co. offers a window into a southern community\u27s struggles with a divided social order, the introduction of wealth into local politics, and a changing economy

Disentangling Viral Entry Kinetics Using Lipid Bilayers Coating Silica Nanoparticles

Enveloped viruses infect cells via fusion between the viral envelope and a cellular membrane. This membrane fusion process is driven by viral proteins, but slow stochastic protein activation dominates fusion kinetics, making it challenging to probe the role of membrane mechanics in viral entry directly. We have used bilayer-coated silica nanoparticles to restrict the deformability of lipid membranes in a controllable manner. These bilayer-coated nanoparticles are then used in a single-particle fusion assay with infectious influenza virus. We observe that as we vary the free energy of membrane deformation by changing nanoparticle size, we obtain a corresponding response in fusion kinetics and apparent fusion protein stoichiometry. We thus directly measure the effect of membrane deformability on the free-energy barrier to membrane fusion by influenza, overcoming the masking effect of slow protein activation kinetics. </div

Measuring single-virus fusion kinetics using an assay for nucleic acid exposure

The kinetics by which individual enveloped viruses fuse with membranes provide an important window into viral-entry mechanisms. We have developed a real-time assay using fluorescent probes for single-virus genome exposure than can report on stages of viral entry including or subsequent to fusion pore formation and prior to viral genome trafficking. We accom-plish this using oxazole yellow nucleic-acid-binding dyes, which can be encapsulated in the lumen of target membranes to permit specific detection of fusion events. Since increased fluorescence of the dye occurs only when it encounters viral genome via a fusion pore and binds, this assay excludes content leakage without fusion. Using this assay, we show that influenza virus fuses with liposomes of different sizes with indistinguishable kinetics by both testing liposomes extruded through pores of different radii and showing that the fusion kinetics of individual liposomes are uncorrelated with the size of the liposome. These results suggest that the starting curvature of such liposomes does not control the rate-limiting steps in influenza entry

Lysosomotropic agents: impact on lysosomal membrane permeabilization and cell death

Lysosomes are acidic organelles essential for degradation, signalling and cell homoeostasis. In addition, they play a key role in cell death. Permeabilization of the lysosomal membrane and release of hydrolytic enzymes to the cytosol accompanies apoptosis signalling in several systems. The regulatory mechanism of lysosomal stability is, however, poorly understood. Lipophilic or amphiphilic compounds with a basic moiety will become protonated and trapped within lysosomes, and such lysosomotropic behaviour is also found in many pharmacological drugs. The natural sphingolipid sphingosine exhibits lysosomotropic detergent ability and is an endogenous candidate for controlling lysosomal membrane permeabilization. The lysosomotropic properties of certain detergents might be of use in lysosome-targeting anticancer drugs and drug delivery system in the future. The present review summarizes the current knowledge on the targeting and permeabilizing properties of lysosomotropic detergents from a cellular and physicochemical perspective.Funding Agencies|Swedish Research Council [3214]; Konung Gustaf V:s och Drottning Victorias Frimurarestiftelse</p

Influenza Virus Membrane Fusion Is Promoted by the Endosome-Resident Phospholipid Bis(monoacylglycero)phosphate

The phospholipid bis(monoacylglycero)phosphate (BMP) is enriched in late endosomal and endolysosomal membranes and is believed to be involved in membrane deformation and generation of intralumenal vesicles within late endosomes. Previous studies have demonstrated that BMP promotes membrane fusion of several enveloped viruses, but a limited effect has been found on influenza virus. Here, we report the use of single-virus fusion assays to dissect BMP’s effect on influenza virus fusion in greater depth. In agreement with prior reports, we found that hemifusion kinetics and efficiency were unaffected by the addition of 10–20 mol % BMP to the target membrane. However, using an assay for fusion pore formation and genome exposure, we found full fusion efficiency to be substantially enhanced by the addition of 10–20 mol % BMP to the target membrane, while the kinetics remained unaffected. By comparing BMP to other negatively charged phospholipids, we found the effect on fusion efficiency mainly attributable to headgroup charge, although we also hypothesize a role for BMP’s unusual chemical structure. Our results suggest that BMP function as a permissive factor for a wider range of viruses than previously reported. We hypothesize that BMP may be a general cofactor for endosomal entry of enveloped viruses