Bioinspired Self-Assembly of Metalloporphyrins and Polyelectrolytes into Hierarchical Supramolecular Nanostructures for Enhanced Photocatalytic H2 Production in Water.

Polypeptides, as natural polyelectrolytes, are assembled into tailored proteins to integrate chromophores and catalytic sites for photosynthesis. Mimicking nature to create the water-soluble nanoassemblies from synthetic polyelectrolytes and photocatalytic molecular species for artificial photosynthesis is still rare. Here, we report the enhancement of the full-spectrum solar-light-driven H2 production within a supramolecular system built by the co-assembly of anionic metalloporphyrins with cationic polyelectrolytes in water. This supramolecular photocatalytic system achieves a H2 production rate of 793 and 685 µmol h-1 g-1 over 24 h with a combination of Mg or Zn porphyrin as photosensitizers and Cu porphyrin as a catalyst, which is more than 23 times higher than that of free molecular controls. With a photosensitizer to catalyst ratio of 10000 : 1, the highest H2 production rate of >51,700 µmol h-1 g-1 with a turnover number (TON) of >1,290 per molecular catalyst was achieved over 24 h irradiation. The hierarchical self-assembly not only enhances photostability through forming ordered stackings of the metalloporphyrins but also facilitates both energy and electron transfer from antenna molecules to catalysts, and therefore promotes the photocatalysis. This study provides structural and mechanistic insights into the self-assembly enhanced photostability and catalytic performance of supramolecular photocatalytic systems.

Progressive Excitability Changes in the Medial Entorhinal Cortex in the 3xTg Mouse Model of Alzheimer's Disease Pathology.

Alzheimer's disease (AD) is a chronic neurodegenerative disorder characterized by memory loss and progressive cognitive impairments. In mouse models of AD pathology, studies have found neuronal and synaptic deficits in hippocampus, but less is known about changes in medial entorhinal cortex (MEC), which is the primary spatial input to the hippocampus and an early site of AD pathology. Here, we measured neuronal intrinsic excitability and synaptic activity in MEC layer II (MECII) stellate cells, MECII pyramidal cells, and MEC layer III (MECIII) excitatory neurons at 3 and 10 months of age in the 3xTg mouse model of AD pathology, using male and female mice. At 3 months of age, before the onset of memory impairments, we found early hyperexcitability in intrinsic properties of MECII stellate and pyramidal cells, but this was balanced by a relative reduction in synaptic excitation (E) compared with inhibition (I; E/I ratio), suggesting intact homeostatic mechanisms regulating MECII activity. Conversely, MECIII neurons had reduced intrinsic excitability at this early time point with no change in synaptic E/I ratio. By 10 months of age, after the onset of memory deficits, neuronal excitability of MECII pyramidal cells and MECIII excitatory neurons was largely normalized in 3xTg mice. However, MECII stellate cells remained hyperexcitable, and this was further exacerbated by an increased synaptic E/I ratio. This observed combination of increased intrinsic and synaptic hyperexcitability suggests a breakdown in homeostatic mechanisms specifically in MECII stellate cells at this postsymptomatic time point, which may contribute to the emergence of memory deficits in AD.SIGNIFICANCE STATEMENT AD causes cognitive deficits, but the specific neural circuits that are damaged to drive changes in memory remain unknown. Using a mouse model of AD pathology that expresses both amyloid and tau transgenes, we found that neurons in the MEC have altered excitability. Before the onset of memory impairments, neurons in layer 2 of MEC had increased intrinsic excitability, but this was balanced by reduced inputs onto the cell. However, after the onset of memory impairments, stellate cells in MEC became further hyperexcitable, with increased excitability exacerbated by increased synaptic inputs. Thus, it appears that MEC stellate cells are uniquely disrupted during the progression of memory deficits and may contribute to cognitive deficits in AD.

Chronotate: An open-source tool for manual timestamping and quantification of animal behavior.

A core necessity to behavioral neuroscience research is the ability to accurately measure performance on behavioral assays, such as the novel object location and novel object recognition tasks. These tasks are widely used in neuroscience research and measure a rodent's instinct for investigating novel features as a proxy to test their memory of a previous experience. Automated tools for scoring behavioral videos can be cost prohibitive and often have difficulty distinguishing between active investigation of an object and simply being in close proximity to an object. As such, many experimenters continue to rely on hand scoring interactions using stopwatches, which makes it difficult to review scoring after-the-fact and results in the loss of temporal information. Here, we introduce Chronotate, a free, open-source tool to aid in manually scoring novel object behavior videos. The software consists of an interactive video player with keyboard integration for marking timestamps of behavioral events during video playback, making it simple to quickly score and review bouts of rodent-object interaction. In addition, Chronotate outputs detailed interaction bout data, allowing for nuanced behavioral performance analyses. Using this detailed temporal information, we demonstrate that novel object location performance peaks within the first 3 s of interaction time and preference for the novel location becomes reduced across the test session. Thus, Chronotate can be used to determine the temporal structure of interactions on this task and can provide new insight into the memory processes that drive this behavior. Chronotate is available for download at: https://github.com/ShumanLab/Chronotate.

Progressive excitability changes in the medial entorhinal cortex in the 3xTg mouse model of Alzheimer's disease pathology.

Alzheimer's disease (AD) is a chronic neurodegenerative disorder that is characterized by memory loss and progressive cognitive impairments. In mouse models of AD pathology, studies have found neuronal and synaptic deficits in the hippocampus, but less is known about what happens in the medial entorhinal cortex (MEC), which is the primary spatial input to the hippocampus and an early site of AD pathology. Here, we measured the neuronal intrinsic excitability and synaptic activity in MEC layer II (MECII) stellate cells, MECII pyramidal cells, and MEC layer III (MECIII) excitatory neurons at early (3 months) and late (10 months) time points in the 3xTg mouse model of AD pathology. At 3 months of age, prior to the onset of memory impairments, we found early hyperexcitability in MECII stellate and pyramidal cells' intrinsic properties, but this was balanced by a relative reduction in synaptic excitation (E) compared to inhibition (I), suggesting intact homeostatic mechanisms regulating activity in MECII. Conversely, MECIII neurons had reduced intrinsic excitability at this early time point with no change in the synaptic E/I ratio. By 10 months of age, after the onset of memory deficits, neuronal excitability of MECII pyramidal cells and MECIII excitatory neurons was largely normalized in 3xTg mice. However, MECII stellate cells remained hyperexcitable and this was further exacerbated by an increased synaptic E/I ratio. This observed combination of increased intrinsically and synaptically generated excitability suggests a breakdown in homeostatic mechanisms specifically in MECII stellate cells at this post-symptomatic time point. Together, these data suggest that the breakdown in homeostatic excitability mechanisms in MECII stellate cells may contribute to the emergence of memory deficits in AD.

Dissociable contributions of the amygdala and ventral hippocampus to stress-induced changes in defensive behavior.

Severe stress can produce multiple persistent changes in defensive behavior. While much is known about the circuits supporting stress-induced associative fear responses, how circuit plasticity supports the broader changes in defensive behavior observed after severe stress remains unclear. Here, we find that stress-induced plasticity in the ventral hippocampus (vHC) and basolateral amygdala (BLA) support doubly dissociable defensive behavioral changes. Stress-induced protein synthesis in the BLA was found to support lasting enhancements in stress sensitivity but not enhancements in exploratory anxiety-related behaviors, whereas protein synthesis in the vHC was found to support enhancements in anxiety-related behavior but not enhancements in stress sensitivity. Like protein synthesis, neuronal activity of the BLA and vHC were found to differentially support the expression of these same defensive behaviors. Lastly, blockade of associative fear had no impact on stress-induced changes in anxiety-related behavior. These findings highlight that multiple memory-systems support stress-induced defensive behavior changes.

Ensemble-specific deficit in neuronal intrinsic excitability in aged mice.

With the prevalence of age-related cognitive deficits on the rise, it is essential to identify cellular and circuit alterations that contribute to age-related memory impairment. Increased intrinsic neuronal excitability after learning is important for memory consolidation, and changes to this process could underlie memory impairment in old age. Some studies find age-related deficits in hippocampal neuronal excitability that correlate with memory impairment but others do not, possibly due to selective changes only in activated neural ensembles. Thus, we tagged CA1 neurons activated during learning and recorded their intrinsic excitability 5 hours or 7 days post-training. Adult mice exhibited increased neuronal excitability 5 hours after learning, specifically in ensemble (learning-activated) CA1 neurons. As expected, ensemble excitability returned to baseline 7 days post-training. In aged mice, there was no ensemble-specific excitability increase after learning, which was associated with impaired hippocampal memory performance. These results suggest that CA1 may be susceptible to age-related impairments in post-learning ensemble excitability and underscore the need to selectively measure ensemble-specific changes in the brain.

A host-guest interaction activated Bobbitt oxidant for highly efficient oxidation of alcohols.

Host-guest complexation using hydrogen-bonded macrocycles was found to enable activation of the Bobbitt oxidant reagent, which greatly facilitates the highly efficient oxidation of unactivated primary alcohols. This work provides a complementary approach to the activation of Bobbitt's salt with shape-persistent macrocycles in supramolecular catalysis.

Minian, an open-source miniscope analysis pipeline.

Miniature microscopes have gained considerable traction for in vivo calcium imaging in freely behaving animals. However, extracting calcium signals from raw videos is a computationally complex problem and remains a bottleneck for many researchers utilizing single-photon in vivo calcium imaging. Despite the existence of many powerful analysis packages designed to detect and extract calcium dynamics, most have either key parameters that are hard-coded or insufficient step-by-step guidance and validations to help the users choose the best parameters. This makes it difficult to know whether the output is reliable and meets the assumptions necessary for proper analysis. Moreover, large memory demand is often a constraint for setting up these pipelines since it limits the choice of hardware to specialized computers. Given these difficulties, there is a need for a low memory demand, user-friendly tool offering interactive visualizations of how altering parameters at each step of the analysis affects data output. Our open-source analysis pipeline, Minian (miniscope analysis), facilitates the transparency and accessibility of single-photon calcium imaging analysis, permitting users with little computational experience to extract the location of cells and their corresponding calcium traces and deconvolved neural activities. Minian contains interactive visualization tools for every step of the analysis, as well as detailed documentation and tips on parameter exploration. Furthermore, Minian has relatively small memory demands and can be run on a laptop, making it available to labs that do not have access to specialized computational hardware. Minian has been validated to reliably and robustly extract calcium events across different brain regions and from different cell types. In practice, Minian provides an open-source calcium imaging analysis pipeline with user-friendly interactive visualizations to explore parameters and validate results.

The role of intrinsic excitability in the evolution of memory: Significance in memory allocation, consolidation, and updating.

Memory is a dynamic process that is continuously regulated by both synaptic and intrinsic neural mechanisms. While numerous studies have shown that synaptic plasticity is important in various types and phases of learning and memory, neuronal intrinsic excitability has received relatively less attention, especially regarding the dynamic nature of memory. In this review, we present evidence demonstrating the importance of intrinsic excitability in memory allocation, consolidation, and updating. We also consider the intricate interaction between intrinsic excitability and synaptic plasticity in shaping memory, supporting both memory stability and flexibility.

Breakdown of spatial coding and interneuron synchronization in epileptic mice.

Temporal lobe epilepsy causes severe cognitive deficits, but the circuit mechanisms remain unknown. Interneuron death and reorganization during epileptogenesis may disrupt the synchrony of hippocampal inhibition. To test this, we simultaneously recorded from the CA1 and dentate gyrus in pilocarpine-treated epileptic mice with silicon probes during head-fixed virtual navigation. We found desynchronized interneuron firing between the CA1 and dentate gyrus in epileptic mice. Since hippocampal interneurons control information processing, we tested whether CA1 spatial coding was altered in this desynchronized circuit, using a novel wire-free miniscope. We found that CA1 place cells in epileptic mice were unstable and completely remapped across a week. This spatial instability emerged around 6 weeks after status epilepticus, well after the onset of chronic seizures and interneuron death. Finally, CA1 network modeling showed that desynchronized inputs can impair the precision and stability of CA1 place cells. Together, these results demonstrate that temporally precise intrahippocampal communication is critical for spatial processing.

Restricting Growth of Ni3Fe Nanoparticles on Heteroatom-Doped Carbon Nanotube/Graphene Nanosheets as Air-Electrode Electrocatalyst for Zn-Air Battery.

Exploring bifunctional oxygen electrode catalysts with efficient and stable oxygen reduction reaction (ORR)/oxygen evolution reaction (OER) performance is one of the limitations for high-performance zinc-air battery. In this work, Ni3Fe alloy nanoparticles incorporated in three-dimensional (3D) carbon nanotube (CNT)/graphene nanosheet composites with N and S codoping (Ni3Fe/N-S-CNTs) as bifunctional oxygen electrode electrocatalysts for zinc-air battery. The main particle size of Ni3Fe nanoparticles could be well restricted because of the unique 3D structure of carbon nanotube/graphene nanosheet composites (N-S-CNTs). The large specific area of N-S-CNTs is conducive to the uniform dispersion of Ni3Fe nanoparticles. On the basis of the synergistic effect of Ni3Fe nanoparticles with N-S-CNTs, and the sufficient exposure of reactive sites, the synthesized Ni3Fe/N-S-CNTs catalyst exhibits excellent OER performance with a low overpotential of 215 mV at 10 mA cm-2, and efficient ORR activity with a half-wave potential of 0.877 V. When used as an electrocatalyst in zinc-air battery, the device exhibits a power density of 180.0 mW cm-2 and long term durability for 500 h.

Novel Quantitative Analyses of Spontaneous Synaptic Events in Cortical Pyramidal Cells Reveal Subtle Parvalbumin-Expressing Interneuron Dysfunction in a Knock-In Mouse Model of Alzheimer's Disease.

Alzheimer's disease (AD) is a neurodegenerative disorder that has become a compelling global public health concern. Besides pathological hallmarks such as extracellular amyloid plaques, intracellular neurofibrillary tangles (NFTs), and loss of neurons and synapses, clinical reports have shown that epileptiform activity, even seizures, can occur early in the disease. Aberrant synaptic and network activities as well as epileptiform discharges have also been observed in various mouse models of AD. The new AppNL-F mouse model is generated by a gene knock-in approach and there are limited studies on basic synaptic properties in AppNL-F mice. Therefore, we applied quantitative methods to analyze spontaneous excitatory and inhibitory synaptic events in parietal cortex layer 2/3 pyramidal cells. First, by an objective amplitude distribution analysis, we found decreased amplitudes of spontaneous IPSCs (sIPSCs) in aged AppNL-F mice caused by a reduction in the amplitudes of the large sIPSCs with fast rates of rise, consistent with deficits in the function of parvalbumin-expressing interneurons (PV INs). Second, we calculated the burstiness and memory in a series of successive synaptic events. Lastly, by using a novel approach to determine the excitation-to-inhibition (E/I) ratio, we found no changes in the AppNL-F mice, indicating that homeostatic mechanisms may have maintained the overall balance of excitation and inhibition in spite of a mildly impaired PV IN function.

[Case-matched study of pcbs toxiciy effects to women and children case in the areas which disused transformers were dismantled].

OBJECTIVE: To Study the health-related effects of PCBs pollution to women and children living near the dismantling factories of disused transformers. METHODS: 49 couples which include a pair of preschool child(8 - 10 years old) and his/her mother were matched as the objects from the central junior school of F neighborhood where the study was progressing. Fasting Venous blood was collected from the objects, in which the content of PCBs (including 13 isomers) was determined by ultrasonic trace analyses methods as well as blood and urine were subjected to biochemical test while investigation by questionnaire and physical examination were also required. RESULTS: The mean content(G) of PCBs is 176ng/g lipid in the venous blood of the women and 192 ng/g lipid in that of the children. There are 6% of the females found blood pressure abnormality in the physical examination, while 28% of those were found urinary routine abnormality and 4% lymph node tumefaction. Among the children, 82% of them were suffered from caries, 6% were found lymph node tumefaction and 16% urinary abnormality. CONCLUSIONS: Both the results of the blood and urine biochemical analyses as well as the physical examination indicated the prevalent abnormal status of the women and children in the area. The accumulating concentration of the PCBs in blood suggested that the dismantling of the disused transformers had resulted in a noticeable negative effect to the local environment.