Interaction between herbivore defense and microbial signaling: bacterial quorum-sensing compounds weaken JA-mediated herbivore resistance in Nicotiana attenuata

Bacteria play important roles in plant–herbivore interactions and communicate with each other with chemical signals, often N-acylhomoserine lactones (AHL). Plant responses to these signals may influence resistance to microbial attack, but the effects of these signals on herbivore defense are unstudied. To determine whether AHL influence jasmonate (JA)-mediated herbivore resistance in Nicotiana attenuata, we treated wild-type (WT) and JA-deficient genotypes (antisense expression of NaLOX3) with N-hexanoyl-dl-homoserine lactone (C6-HSL) and measured the performance of Manduca sexta larvae. Larval mass gain on C6-HSL-treated WT plants was equivalent to that on non-treated NaLOX3-silenced plants, but significantly 4.1-fold larger than on untreated WT plants. Mass gain was unaffected by C6-HSL treatment of NaLOX3-silenced plants. Microarray analysis of the plants elicited with C6-HSL and JA inducing fatty acid–amino acid conjugates revealed a down-regulation of a proteinase inhibitor in the C6-HSL-treated WT plants. The results therefore suggest that the increased performance of M. sexta was due to direct or indirect effect of C6-HSL on JA-mediated defenses.     

Combined sclerochronologic and oxygen isotope analysis of gastropod shells (Gibbula cineraria, North Sea): life-history traits and utility as a high-resolution environmental archive for kelp forests

The grey top-shell, Gibbula cineraria is a common member of temperate to cold water kelp forest communities, but its longevity and the age structure of its populations remains unresolved. Combined measurements of shell growth rates (sclerochronology) and oxygen isotope composition allow analysis of rate and timing of shell growth. Eight specimens were analyzed from the southern North Sea (near Helgoland, German Bight). Three age groups were identified but external measurements (width, height, ornamentation patterns and number of whorls) and shell weight are not adequate for ontogenetic age discrimination. Stable oxygen isotope data is consistent with shell growth during the interval from April to December in isotopic equilibrium with seawater, and growth increments exhibit strong tidal controls with fortnightly bundles well preserved. Reliable environmental proxy data (water temperature) can be extracted from the shell aragonite using conventional stable oxygen isotope analyses, with a temporal resolution of days attainable during intervals of maximum growth, but annual extremes are not always recorded in the shell. While demonstrating the utility of G. cineraria as a environmental and potential paleoenvironmental proxy for kelp forest habitats, its longevity has been significantly overestimated.     

National Prevention through Design (PtD) Initiative

INTRODUCTION: The most effective means of preventing and controlling occupational injuries, illness, and fatalities is to "design out" hazards and hazardous exposures from the workplace. There is a long history of designing for safety for the general public and to a lesser degree for workers. METHOD: We now have the experience and insight from thoughtful, previous efforts to call for a comprehensive national strategy to implement a Prevention through Design (PtD) Initiative. RESULTS: This paper describes that initiative in terms of four overarching areas where action can be directed: practice, policy, research, and education. To obtain stakeholder input for issues in these four areas and to focus implementation efforts, eight sector divisions of the economy will be addressed. A seven year strategy is envisioned.     

Vascular plant extinction in the continental United States and Canada

Extinction rates are expected to increase during the Anthropocene. Current extinction rates of plants and many animals remain unknown. We quantified extinctions among the vascular flora of the continental United States and Canada since European settlement. We compiled data on apparently extinct species by querying plant conservation databases, searching the literature, and vetting the resulting list with botanical experts. Because taxonomic opinion varies widely, we developed an index of taxonomic uncertainty (ITU). The ITU ranges from A to F, with A indicating unanimous taxonomic recognition and F indicating taxonomic recognition by only a single author. The ITU allowed us to rigorously evaluate extinction rates. Our data suggest that 51 species and 14 infraspecific taxa, representing 33 families and 49 genera of vascular plants, have become extinct in our study area since European settlement. Seven of these taxa exist in cultivation but are extinct in the wild. Most extinctions occurred in the west, but this outcome may reflect the timing of botanical exploration relative to settlement. Sixty-four percent of extinct plants were single-site endemics, and many occurred outside recognized biodiversity hotspots. Given the paucity of plant surveys in many areas, particularly prior to European settlement, the actual extinction rate of vascular plants is undoubtedly much higher than indicated here.