553 research outputs found
Use of the wound healing trajectory as an outcome determinant for acute wound healing
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/72454/1/j.1524-475x.2000.00511.x.pd
The sensory features of a food cue influence its ability to act as an incentive stimulus and evoke dopamine release in the nucleus accumbens core
The sensory properties of a reward-paired cue (a Conditioned Stimulus; CS) may impact the motivational value attributed to the cue, and in turn influence the form of the conditioned response (CR) that develops. A cue with multiple sensory qualities, such as a moving lever-CS, may activate numerous neural pathways that process auditory and visual information, resulting in CRs that vary both within and between individuals. For example, CRs include approach to the lever-CS itself (rats that āsign-track;ā ST), approach to the location of reward delivery (rats that āgoal-track;ā GT), or an āintermediateā combination of these behaviors. We found that the multimodal sensory features of the lever-CS were important to the development and expression of sign-tracking. When the lever-CS was covered, and thus could only be heard moving, STs continued to approach the lever location, but also started to approach the food cup during the CS period. While still predictive of reward, the auditory component of the lever-CS was a much weaker conditioned reinforcer than the visible lever-CS. This plasticity in behavioral responding observed in STs closely resembled behaviors normally seen in rats classified as āintermediates.ā Furthermore, the ability of both the lever-CS and reward-delivery to evoke dopamine release in the nucleus accumbens was also altered by covering the lever ā dopamine signaling in STs resembled neurotransmission observed in rats that normally only GT. These data suggest that while the visible lever-CS was attractive, wanted, and had incentive value for STs, when presented in isolation the auditory component of the cue was simply predictive of reward, lacking incentive salience. Therefore, the specific sensory features of cues may differentially contribute to responding and ensure behavioral flexibility
Herbicide-resistant weeds : from research and knowledge to future needs
Synthetic herbicides have been used globally to control weeds in major field crops. This has imposed a strong selection for any trait that enables plant populations to survive and reproduce in the presence of the herbicide. Herbicide resistance in weeds must be minimized because it is a major limiting factor to food security in global agriculture. This represents a huge challenge that will require great research efforts to develop control strategies as alternatives to the dominant and almost exclusive practice of weed control by herbicides. Weed scientists, plant ecologists and evolutionary biologists should join forces and work towards an improved and more integrated understanding of resistance across all scales. This approach will likely facilitate the design of innovative solutions to the global herbicide resistance challenge
Amyloid-Ī² nanotubes are associated with prion protein-dependent synaptotoxicity
Growing evidence suggests water-soluble, non-fibrillar forms of amyloid-Ī² protein (AĪ²) have important roles in Alzheimer's disease with toxicities mimicked by synthetic AĪ²1-42. However, no defined toxic structures acting via specific receptors have been identified and roles of proposed receptors, such as prion protein (PrP), remain controversial. Here we quantify binding to PrP of AĪ²1-42 after different durations of aggregation. We show PrP-binding and PrP-dependent inhibition of long-term potentiation (LTP) correlate with the presence of protofibrils. Globular oligomers bind less avidly to PrP and do not inhibit LTP, whereas fibrils inhibit LTP in a PrP-independent manner. That only certain transient AĪ² assemblies cause PrP-dependent toxicity explains conflicting reports regarding the involvement of PrP in AĪ²-induced impairments. We show that these protofibrils contain a defined nanotubular structure with a previously unidentified triple helical conformation. Blocking the formation of AĪ² nanotubes or their interaction with PrP might have a role in treatment of Alzheimer's disease
Weed resistance to synthetic auxin herbicides
Herbicides classified as synthetic auxins have been most commonly used to control broadleaf weeds in a variety of crops and in non-cropland areas since the first synthetic auxin herbicide (SAH), 2,4-D, was introduced to the market in the mid-1940s. The incidence of weed species resistant to SAHs is relatively low considering their long-term global application with 29 broadleaf weed species confirmed resistant to date. An understanding of the context and mechanisms of SAH resistance evolution can inform management practices to sustain the longevity and utility of this important class of herbicides. A symposium was convened during the 2nd Global Herbicide Resistance Challenge (May 2017 in Denver, CO, USA) to provide an overview of the current state of knowledge of SAH resistance mechanisms including case studies of weed species resistant to SAHs and perspectives on mitigating resistance development in SAH-tolerant crops
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Amyloid-Ī² nanotubes are associated with prion protein-dependent synaptotoxicity
Growing evidence suggests water-soluble, non-fibrillar forms of amyloid-Ī² protein (AĪ²) have important roles in Alzheimerās disease with toxicities mimicked by synthetic AĪ²1ā42. However, no defined toxic structures acting via specific receptors have been identified and roles of proposed receptors, such as prion protein (PrP), remain controversial. Here we quantify binding to PrP of AĪ²1ā42 after different durations of aggregation. We show PrP-binding and PrP-dependent inhibition of long-term potentiation (LTP) correlate with the presence of protofibrils. Globular oligomers bind less avidly to PrP and do not inhibit LTP, whereas fibrils inhibit LTP in a PrP-independent manner. That only certain transient AĪ² assemblies cause PrP-dependent toxicity explains conflicting reports regarding the involvement of PrP in AĪ²-induced impairments. We show that these protofibrils contain a defined nanotubular structure with a previously unidentified triple helical conformation. Blocking the formation of AĪ² nanotubes or their interaction with PrP might have a role in treatment of Alzheimerās disease
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A highly-resolved food web for insect seed predators in a species-rich tropical forest
The top-down and indirect effects of insects on plant communities depend on patterns of host use, which are often poorly documented, particularly in species-rich tropical forests. At Barro Colorado Island, Panama, we compiled the first food web quantifying trophic interactions between the majority of co-occurring woody plant species and their internally-feeding insect seed predators. Our study is based on more than 200,000 fruits representing 478 plant species, associated with 369 insect species. Insect host-specificity was remarkably high: only 20% of seed predator species were associated with more than one plant species, while each tree species experienced seed predation from a median of two insect species. Phylogeny, but not plant traits, explained patterns of seed predator attack. These data suggest that seed predators are unlikely to mediate indirect interactions such as apparent competition between plant species, but are consistent with their proposed contribution to maintaining plant diversity via the Janzen-Connell mechanism
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