Controlling Interneuron Activity in Caenorhabditis Elegans to Evoke Chemotactic Behaviour

Animals locate and track chemoattractive gradients in the environment to find food. With its small nervous system, Caenorhabditis elegans is a good model system in which to understand how the dynamics of neural activity control this search behaviour. Extensive work on the nematode has identified the neurons that are necessary for the different locomotory behaviours underlying chemotaxis through the use of laser ablation, activity recording in immobilized animals and the study of mutants. However, we do not know the neural activity patterns in C. elegans that are sufficient to control its complex chemotactic behaviour. To understand how the activity in its interneurons coordinate different motor programs to lead the animal to food, here we used optogenetics and new optical tools to manipulate neural activity directly in freely moving animals to evoke chemotactic behaviour. By deducing the classes of activity patterns triggered during chemotaxis and exciting individual neurons with these patterns, we identified interneurons that control the essential locomotory programs for this behaviour. Notably, we discovered that controlling the dynamics of activity in just one interneuron pair (AIY) was sufficient to force the animal to locate, turn towards and track virtual light gradients. Two distinct activity patterns triggered in AIY as the animal moved through the gradient controlled reversals and gradual turns to drive chemotactic behaviour. Because AIY neurons are post-synaptic to most chemosensory and thermosensory neurons, it is probable that these activity patterns in AIY have an important role in controlling and coordinating different taxis behaviours of the animal.Engineering and Applied SciencesMolecular and Cellular Biolog

Intestinal mucosal injury induced by obstructive jaundice is associated with activation of TLR4/TRAF6/NF-κB pathways.

OBJECTIVES:To investigate the role of TLR4/TRAF6/NF-κB pathways in intestinal mucosal injury induced by obstructive jaundice (OJ). METHODS:A total of 100 male C57BL/6J mice were randomly assigned to two groups: (I) sham operation (SH); (II) OJ. The mice were sacrificed before operation and on the 1st, 3rd, 5th and 7th day after operation. The blood and terminal ileum were simultaneously collected under the aseptic condition for further detection. RESULTS:In the SH group, TLR4 protein and mRNA rarely expressed in the intestinal mucosa of the mice and there were no significant differences at different time points (p>0.05). By contrast, in the OJ group TLR4 protein (0.12±0.06, 0.16±0.08, 0.27±0.10, 0.35±0.12 and 0.41±0.13, respectively) and mRNA (0.49±0.19, 0.62±0.23, 0.98±0.32, 1.42±0.41 and 1.72±0.49, respectively) increased gradually with the extension of time (p<0.05). Also in the OJ group, the levels of DAO and endotoxin in plasma as well as the expressions of NF-κB and caspase-3 increased gradually with the extension of time, showing positive correlation with the expression of TLR4 (p<0.05). CONCLUSIONS:The expression of TLR4 was significantly up-regulated in the distal ileum of mice with OJ. Activation of the TLR4/TRAF6/NF-κB pathways was involved in the occurrence and development of intestinal mucosal injury and endotoxemia in mice with OJ

Correction: Intestinal mucosal injury induced by obstructive jaundice is associated with activation of TLR4/TRAF6/NF-κB pathways.

[This corrects the article DOI: 10.1371/journal.pone.0223651.]

MoSe₂/g-C₃N₄ heterojunction coupled with Pt nanoparticles for enhanced photocatalytic hydrogen evolution

The inefficiency of charge separation is the major practically limited factor towards high hydrogen evolution reaction (HER) of photocatalysts. Therefore, design and construction of efficient photocatalysts system with efficient charge transfer path is urgently necessary for HER. Herein, we report an effective strategy to construct Pt–MoSe2/g-C3N4 heterostructure through integrating facile solvothermal technique and solution-phase hybridization method. The synthesized ternary Pt–MoSe2/g-C3N4 heterostructures exhibit greatly enhanced photocatalytic hydrogen production than bare g-C3N4 and Pt/g-C3N4 catalyst. The enhancement factor is directly correlated with strong photosynergistic effect of charge-carrier generation and separation path coupling heterojunction sensitization on MoSe2/g-C3N4 with Pt nanoparticle. Moreover, the mechanism of enhanced catalytic activity is fully studied by electrochemical characterizations and photocurrent analysis.Ministry of Education (MOE)Accepted versionThe authors acknowledge the financial support from the Scientific research projects funded by Hebei talent project training funds (A201803003), the Program for the Young Top Talents of Hebei Province, the Natural Science Foundation of Hebei Province (grant no. B2019402082) and the Science and Technology Research and Development Projects of Handan City (19422111008-16), W.L. Zhen and C. Xue thank the support from the Ministry of Education, Singapore, under AcRF-Tier 2 (MOE2018-T2-1-017) and AcRF-Tier 1 (MOE2019-T1-002- 012, RG102/19)

Flow of Cortical Activity Underlying a Tactile Decision in Mice

Perceptual decisions involve distributed cortical activity. Does information flow sequentially from one cortical area to another, or do networks of interconnected areas contribute at the same time? Here we delineate when and how activity in specific areas drives a whisker-based decision in mice. A short-term memory component temporally separated tactile “sensation” and “action” (licking). Using optogenetic inhibition (spatial resolution, 2 mm; temporal resolution, 100 ms), we surveyed the neocortex for regions driving behavior during specific behavioral epochs. Barrel cortex was critical for sensation. During the short-term memory, unilateral inhibition of anterior lateral motor cortex biased responses to the ipsilateral side. Consistently, barrel cortex showed stimulus-specific activity during sensation, whereas motor cortex showed choice-specific preparatory activity and movement-related activity, consistent with roles in motor planning and movement. These results suggest serial information flow from sensory to motor areas during perceptual decision making.Howard Hughes Medical Institut

Spatiotemporal constraints on optogenetic inactivation in cortical circuits

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