Taste aversion learning in young and adult rats.

Compared a total of 159 male Long-Evans rat pups and adults on their ability to learn taste aversions with 1- and 2-bottle tests, 2 different illness-inducing agents and flavors, and varying taste–illness delays. Rat pups learned taste aversions with either 1- or 2-bottle tests, but only with short taste–illness delays. Delays of 60 min were sufficient to block taste aversion learning in pups. Pups also failed to demonstrate neophobia to a novel taste. These findings suggest that pups forget taste information more rapidly than adults, perhaps because taste information is not so salient for pups as for adults. (29 ref) (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Accumulation of atmospheric and sedimentary PCBs and toxaphene in a Lake Michigan food web

Seston, sediment, settling organic matter, and food web members were collected from Grand Traverse Bay, Lake Michigan, between April 1997 and September 1998 to examine PCB and toxaphene biomagnification. Stable isotopes of nitrogen and carbon were analyzed in samples and used to establish trophic structure of the food web and to determine the importance of atmospheric versus sedimentary sources in delivering PCBs to the food web. Nitrogen isotopes were confounded by multiple variables in this system, particularly seasonal variation, and did not display a simple pattern of enrichment among trophic levels. However, delta13C displayed little seasonal variation and was positively correlated with PCB concentrations among food web members (r2 = 0.69). Plots of delta13C vs PCBs separate food web members into three distinct groupings comprised of invertebrates, primary forage fish, and predatory fish. Stable isotope values of the primary organic sources indicate that the atmosphere, and not the sediment, is the most likely source of PCBs to the food web of Lake Michigan. Additionally, we suggest that seston may be important in delivering PCBs to pelagic food web members and species that receive a majority of their nutrition through pelagic sources. In contrast, settling particles are implicated in delivering PCBs to benthic organisms and Mysis relicta.     

The impact of a simulation-based learning design project on studentlearning

This study examined the effects of a sophisticated simulation-based task on students' learning of course-related content, ability to deal with complex, open-ended problems, and attitudes toward the Interactive Site Investigation Software (ISIS) and the course. Students were required to conduct a hazardous waste site investigation using the simulation software designed specifically for the course. ISIS simulated physical processes as well as real-world engineering processes. Assessment of student outcomes was based on the use of constructed-response knowledge maps to measure content understanding, and surveys to measure student attitudes and use of cognitive processes. Students reported very positive attitudes toward the ISIS experience, appeared to have gained substantial knowledge over the course of ISIS use, and perceived the ISIS activity as being generally effective in improving their skills in dealing with complex projects, linking theory to real world applications, and improving their problem-solving performance. Our assessment of student outcomes was a successful first attempt, but more work is needed to validate our measures with advanced students, particularly when the task is complex and requires interdisciplinary knowledge     

Electroantennographic and coupled gas chromatographic-electroantennographic responses of the mediterranean fruit fly,Ceratitis capitata,to male-produced volatiles and mango odor

We have identified five compounds from the headspace of calling male Mediterranean fruit flies (medfly),Ceratitis capitata (Wiedemann), and three compounds from the headspace of ripe mango (Mangifera indica L). using coupled gas chromatographic-electroantennographic (GC-EAG) recordings, coupled gas chromatographic-mass spectrometric (GC-MS) analysis, and electroantennographic (EAG) assays of standards. The male-produced volatiles eliciting responses from female antennae were ethyl-(E)-3-octenoate, geranyl acetate, (E,E)--farnesene, linalool, and indole. An EAG dose-response test of linalool enantiomers and indole with female medfly antennae showed relatively strong EAG activities, but no significant difference between (R)-(-)-linalool and (S)-(+)-linalool. The three mango volatiles were identified as (1S)-(-)--pinene, ethyl octanoate, and-caryophyllene. In addition, a strong antennal response was recorded from a contaminant,-copaene, present in a commercial sample of-caryophyllene. The EAG response amplitudes from both male and female antennae to the above three mango volatiles were significantly greater than to a hexanol control. For both male and female medfly antennae, the greatest EAG responses were elicited by-caryophyllene followed by ethyl octanoate. The mean EAG responses of female antennae to-caryophyllene and (1S)-(-)--pinene were significantly greater than those of male antennae.     

Inhibition Studies of Mycobacterium tuberculosis Salicylate Synthase (MbtI)

Mycobacterium tuberculosis salicylate synthase (MbtI), a member of the chorismate‐utilizing enzyme family, catalyses the first committed step in the biosynthesis of the siderophore mycobactin T. This complex secondary metabolite is essential for both virulence and survival of M. tuberculosis, the etiological agent of tuberculosis (TB). It is therefore anticipated that inhibitors of this enzyme may serve as TB therapies with a novel mode of action. Herein we describe the first inhibition study of M. tuberculosis MbtI using a library of functionalized benzoate‐based inhibitors designed to mimic the substrate (chorismate) and intermediate (isochorismate) of the MbtI‐catalyzed reaction. The most potent inhibitors prepared were those designed to mimic the enzyme intermediate, isochorismate. These compounds, based on a 2,3‐dihydroxybenzoate scaffold, proved to be low‐micromolar inhibitors of MbtI. The most potent inhibitors in this series possessed hydrophobic enol ether side chains at C3 in place of the enol‐pyruvyl side chain found in chorismate and isochorismate.