Distribution and source assignments of polycyclic aromatic and aliphatic hydrocarbons in sediments and biota of the Lafayette River, VA.

The Lafayette River comprises a tidal sub-estuary constrained by an urban watershed that is bounded by residential areas at its upper reaches and port activity at its mouth. We determined the concentrations and distributions of polycyclic aromatic hydrocarbons (PAHs) and aliphatic n-alkanes across 19 sites from headwaters to river mouth in surface sediments (0-2 cm). Potential atmospheric sources were investigated through the analysis of wet and dry deposition samples and intact coals from a major export terminal nearby.

Nonlytic viral spread enhanced by autophagy components.

The cell-to-cell spread of cytoplasmic constituents such as nonenveloped viruses and aggregated proteins is usually thought to require cell lysis. However, mechanisms of unconventional secretion have been described that bypass the secretory pathway for the extracellular delivery of cytoplasmic molecules. Components of the autophagy pathway, an intracellular recycling process, have been shown to play a role in the unconventional secretion of cytoplasmic signaling proteins.

Competing pathways control host resistance to virus via tRNA modification and programmed ribosomal frameshifting.

Viral infection depends on a complex interplay between host and viral factors. Here, we link host susceptibility to viral infection to a network encompassing sulfur metabolism, tRNA modification, competitive binding, and programmed ribosomal frameshifting (PRF). We first demonstrate that the iron-sulfur cluster biosynthesis pathway in Escherichia coli exerts a protective effect during lambda phage infection, while a tRNA thiolation pathway enhances viral infection.

Genome-scale metabolic networks.

During the last decade, models have been developed to characterize cellular metabolism at the level of an entire metabolic network. The main concept that underlies whole-network metabolic modeling is the identification and mathematical definition of constraints. Here, we review large-scale metabolic network modeling, in particular, stoichiometric- and constraint-based approaches.

The virus as metabolic engineer.

Recent genome-wide screens of host genetic requirements for viral infection have reemphasized the critical role of host metabolism in enabling the production of viral particles. In this review, we highlight the metabolic aspects of viral infection found in these studies, and focus on the opportunities these requirements present for metabolic engineers. In particular, the objectives and approaches that metabolic engineers use are readily comparable to the behaviors exhibited by viruses during infection.

A forward-genetic screen and dynamic analysis of lambda phage host-dependencies reveals an extensive interaction network and a new anti-viral strategy.

Latently infecting viruses are an important class of virus that plays a key role in viral evolution and human health. Here we report a genome-scale forward-genetics screen for host-dependencies of the latently-infecting bacteriophage lambda. This screen identified 57 Escherichia coli (E.

A noisy paracrine signal determines the cellular NF-kappaB response to lipopolysaccharide.

Nearly identical cells can exhibit substantially different responses to the same stimulus. We monitored the nuclear localization dynamics of nuclear factor kappaB (NF-kappaB) in single cells stimulated with tumor necrosis factor-alpha (TNF-alpha) and lipopolysaccharide (LPS). Cells stimulated with TNF-alpha have quantitative differences in NF-kappaB nuclear localization, whereas LPS-stimulated cells can be clustered into transient or persistent responders, representing two qualitatively different groups based on the NF-kappaB response.

Genome-wide mapping of allele-specific protein-DNA interactions in human cells.

We describe a high-throughput method, named ChIP-SNP, for the identification of allele-specific protein-DNA interactions throughout the human genome. ChIP-SNP combines chromatin immunoprecipitation (ChIP) with whole-genome single nucleotide polymorphism (SNP) genotyping microarray analysis. We demonstrated that it can be used to accurately identify allele-specific binding of RNA polymerase II (RNAP) in the human fibroblast genome, uncovering imprinted genes and other allele-specific binding events.