Rapid HPLC screening of jasmonate-induced increases in tobacco alkaloids, phenolics, and diterpene glycosides in Nicotiana attenuata

A rapid, HPLC-based screening procedure for the main classes of secondary metabolites in Nicotiana attenuata leaves (alkaloids, phenolics, and diterpene glycosides) is reported. In a single step, leaves are extracted in aqueous acidified (0.5% acetic acid) methanol, and the extracted compounds are separated by reversed-phase HPLC with an acidic water/acetonitrile gradient in <30 min. The utility of the method in quantifying changes in the secondary metabolites after methyl jasmonate treatment of the plants, a treatment known to elicit resistance to herbivores in nature, is illustrated. Methyl jasmonate treatment elicited dramatic increases in some secondary metabolites (caffeoylputrescine, nicotine, and diterpene glycosides increased 12.5-, 1.4-, and 1.9-fold, respectively) but left others, such as rutin, unchanged. Such broad-based analytical screens will help characterize environmental and genetic changes in secondary metabolite profiles.     

Heterogeneous atmospheric reactions: sulfuric Acid aerosols as tropospheric sinks

The collisional reaction probabilities of several atmospheric species on bulk sulfuric acid surfaces indicate that heterogeneous processes may be important in tropospheric chemistry.     

Conserved folding in retroviral proteases: crystal structure of a synthetic HIV-1 protease

The rational design of drugs that can inhibit the action of viral proteases depends on obtaining accurate structures of these enzymes. The crystal structure of chemically synthesized HIV-1 protease has been determined at 2.8 angstrom resolution (R factor of 0.184) with the use of a model based on the Rous sarcoma virus protease structure. In this enzymatically active protein, the cysteines were replaced by alpha-amino-n-butyric acid, a nongenetically coded amino acid. This structure, in which all 99 amino acids were located, differs in several important details from that reported previously by others. The interface between the identical subunits forming the active protease dimer is composed of four well-ordered beta strands from both the amino and carboxyl termini and residues 86 to 94 have a helical conformation. The observed arrangement of the dimer interface suggests possible designs for dimerization inhibitors.     

Oak leaf quality declines in response to defoliation by gypsy moth larvae

Leaves of red oak trees that had been defoliated by gypsy moth larvae during the previous year and again during the period of the study had higher values of tanning coefficients, total phenolics, hydrolyzable and condensed tannins, dry matter contents, and toughness than did leaves of undamaged trees. These changes may influence larval growth and alter the course of further outbreaks.     

Engagement for transformation: Value webs for local food system development

Engagement happens when academics and non-academics form partnerships to create mutual understanding, and then take action together. An example is the “value web” work associated with W. K. Kellogg Foundation’s Food Systems Higher Education–Community Partnership. Partners nationally work on local food systems development by building value webs. “Value chains,” a concept with considerable currency in the private sector, involves creating non-hierarchical relationships among otherwise disparate actors and entities to achieve collective common goals. The value web concept is extended herein by separating the values of the web itself, such as the value of collaboration, from values “in” the web, such as credence values associated with a product or service. By sharing and discussing case examples of work underway around the United States, the authors make a case for employing the value webs concept to represent a strategy for local food systems development, specifically, and for higher education–community partnerships, generally.

Making a network of hydrophobic clusters

The early events in protein folding are often difficult to track. A hydrophobic collapse, during which nonpolar residues are buried away from the polar solvent, has been proposed, but little is known about the role of this collapse in protein folding. In his Perspective, Baldwin discusses the report by Klein-Seetharaman et al., who shed some light on this issue. A network of hydrophobic clusters stabilizes at least one nonnative interaction in unfolded hen lysozyme. In conjunction with earlier studies, the results suggest that this network has a beneficial effect on the folding of the protein.