The Experts below are selected from a list of 49014 Experts worldwide ranked by ideXlab platform
Kathryn E. Arnold - One of the best experts on this subject based on the ideXlab platform.
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Colour cues or spatial cues? Context-dependent preferences in the European greenfinch (Carduelis chloris)
Animal Cognition, 2010Co-Authors: Katherine A. Herborn, Lucille Alexander, Kathryn E. ArnoldAbstract:Using featural cues such as colour to identify ephemeral food can increase foraging efficiency. Featural cues may change over time however; therefore, animals should use spatial cues to relocate food that occurs in a temporally stable position. We tested this hypothesis by measuring the cue preferences of captive greenfinches Carduelis chloris when relocating food hidden in a foraging tray. In these standardised associative learning Trials, greenfinches favoured colour cues when returning to a foraging context that they had encountered before only once (“one-Trial test”) but switched to spatial cues when they had encountered that scenario on ten previous occasions (“Repeated-Trial test”). We suggest that Repeated encounters generated a context in which individuals had a prior expectation of temporal stability, and hence context-dependent cue selection. Next, we trained birds to find food in the absence of colour cues but tested them in the presence of visual distracters. Birds were able to learn spatial cues after one encounter, but only when visual distracters were identical in colouration. When a colourful distracter was present in the test phase, cue selection was random. Unlike the first one-Trial test, birds were not biased towards this colourful visual distracter. Together, these results suggest that greenfinches are able to learn both cue types, colour cue biases represent learning, not simply distraction, and spatial cues are favoured over colour cues only in temporally stable contexts.
Richard M Murray - One of the best experts on this subject based on the ideXlab platform.
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system level studies of a cell free transcription translation platform for metabolic engineering
bioRxiv, 2017Co-Authors: Hirokazu Sato, Hongjun Huang, Stephanie J Culler, Julia Khandurina, Harish Nagarajan, Tae Hoon Yang, Stephen J Van Dien, Richard M MurrayAbstract:Current methods for assembling biosynthetic pathways in microorganisms require a process of Repeated Trial and error and have long design-build-test cycles. We describe the use of a cell-free transcription-translation (TX-TL) system as a biomolecular breadboard for the rapid engineering of the 1,4-butanediol (BDO) pathway. We demonstrate the reliability of TX-TL as a platform for engineering biological systems by undertaking a careful characterization of its transcription and translation capabilities and provide a detailed analysis of its metabolic output. Using TX-TL to survey the design space of the BDO pathway enables rapid tuning of pathway enzyme expression levels for improved product yield. Leveraging TX-TL to screen enzyme variants for improved catalytic activity accelerates design iterations that can be directly applied to in vivo strain development.
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prototyping 1 4 butanediol bdo biosynthesis pathway in a cell free transcription translation tx tl system
bioRxiv, 2015Co-Authors: Stephanie J Culler, Julia Khandurina, Stephen J Van Dien, Richard M MurrayAbstract:Current methods for assembling metabolic pathways require a process of Repeated Trial and error and have a long design-build-test cycle. Further, it remains a challenge to precisely tune enzyme expression levels for maximizing target metabolite production. Recently it was shown that a cell-free transcriptional-translation system (TX-TL) can be used to rapidly prototype novel complex biocircuits as well as metabolic pathways. TX-TL systems allow protein expression from multiple DNA pieces, opening up the possibility of modulating concentrations of DNA encoding individual pathway enzymes and testing the related effect on metabolite production. In this work, we demonstrate TX-TL as a platform for exploring the design space of metabolic pathways using a 1,4-BDO biosynthesis pathway as an example. Using TX-TL, we verified enzyme expression and enzyme activity and identified the conversion of 4-hydroxybutyrate to downstream metabolites as a limiting step of the 1,4-BDO pathway. We further tested combinations of various enzyme expression levels and found increasing downstream enzyme expression levels improved 1,4-BDO production.
Katherine A. Herborn - One of the best experts on this subject based on the ideXlab platform.
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Colour cues or spatial cues? Context-dependent preferences in the European greenfinch (Carduelis chloris)
Animal Cognition, 2010Co-Authors: Katherine A. Herborn, Lucille Alexander, Kathryn E. ArnoldAbstract:Using featural cues such as colour to identify ephemeral food can increase foraging efficiency. Featural cues may change over time however; therefore, animals should use spatial cues to relocate food that occurs in a temporally stable position. We tested this hypothesis by measuring the cue preferences of captive greenfinches Carduelis chloris when relocating food hidden in a foraging tray. In these standardised associative learning Trials, greenfinches favoured colour cues when returning to a foraging context that they had encountered before only once (“one-Trial test”) but switched to spatial cues when they had encountered that scenario on ten previous occasions (“Repeated-Trial test”). We suggest that Repeated encounters generated a context in which individuals had a prior expectation of temporal stability, and hence context-dependent cue selection. Next, we trained birds to find food in the absence of colour cues but tested them in the presence of visual distracters. Birds were able to learn spatial cues after one encounter, but only when visual distracters were identical in colouration. When a colourful distracter was present in the test phase, cue selection was random. Unlike the first one-Trial test, birds were not biased towards this colourful visual distracter. Together, these results suggest that greenfinches are able to learn both cue types, colour cue biases represent learning, not simply distraction, and spatial cues are favoured over colour cues only in temporally stable contexts.
Mark W. Greenlee - One of the best experts on this subject based on the ideXlab platform.
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Stimulus repetition probability effects on repetition suppression are position invariant for faces.
NeuroImage, 2012Co-Authors: Gyula Kovács, Lara Iffland, Zoltán Vidnyánszky, Mark W. GreenleeAbstract:It has been shown that the probability of face repetitions influences the magnitude of repetition-related response reductions (Summerfield et al., 2008), implying that perceptual expectations affect adaptation and repetition suppression processes in the human central nervous system. An unresolved question is whether probability effects are specific for the retinal position of the stimuli or affect stimulus processing globally, throughout the visual field. To address this question we tested whether face repetition probability affects fMRI adaptation (fMRIa) when the Repeated stimuli are presented on the same retinal position, overlapping each other or when they are presented in opposite hemifields. Subjects were exposed to either two identical (Repeated Trial, RT) or two different (alternating Trial, AT) face stimuli. Both types of Trials were presented either in blocks consisting of 75% (Repeated block, RB) or 25% (alternating block, AB) of RTs. We found that repetition probability influences fMRIa equally for overlapping and nonoverlapping arrangements: the signal reduction after RT was more pronounced in RB than in AB for both spatial arrangements of stimulus-pairs. This effect was present in bilateral fusiform and occipital face areas, as well as in the lateral occipital cortex. Our results support the role of stimulus repetition probability in determining fMRIa and shows that the effect is invariant to the retinal position of stimuli.
Lucille Alexander - One of the best experts on this subject based on the ideXlab platform.
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Colour cues or spatial cues? Context-dependent preferences in the European greenfinch (Carduelis chloris)
Animal Cognition, 2010Co-Authors: Katherine A. Herborn, Lucille Alexander, Kathryn E. ArnoldAbstract:Using featural cues such as colour to identify ephemeral food can increase foraging efficiency. Featural cues may change over time however; therefore, animals should use spatial cues to relocate food that occurs in a temporally stable position. We tested this hypothesis by measuring the cue preferences of captive greenfinches Carduelis chloris when relocating food hidden in a foraging tray. In these standardised associative learning Trials, greenfinches favoured colour cues when returning to a foraging context that they had encountered before only once (“one-Trial test”) but switched to spatial cues when they had encountered that scenario on ten previous occasions (“Repeated-Trial test”). We suggest that Repeated encounters generated a context in which individuals had a prior expectation of temporal stability, and hence context-dependent cue selection. Next, we trained birds to find food in the absence of colour cues but tested them in the presence of visual distracters. Birds were able to learn spatial cues after one encounter, but only when visual distracters were identical in colouration. When a colourful distracter was present in the test phase, cue selection was random. Unlike the first one-Trial test, birds were not biased towards this colourful visual distracter. Together, these results suggest that greenfinches are able to learn both cue types, colour cue biases represent learning, not simply distraction, and spatial cues are favoured over colour cues only in temporally stable contexts.