Pressure tuned incommensurability and guest structure transition in compressed scandium from machine learning atomic simulation.

Scandium (Sc) is the lightest non-main-group element and transforms to a host-guest (H-G) incommensurate structure under gigapascal (GPa) pressures. While the host structure is stable over a wide pressure range, the guest structure may exist in multiple forms, featuring different incommensurate ratios, and mixing up to generate long-range "disordered" guest structures. Here, we employed the recently developed global neural network (g-NN) potential and the stochastic surface walking (SSW) global optimization algorithm to explore the global potential energy surface of Sc under various pressures. We probe the global minima structure in a system made of hundreds of atoms and revealed that the solid-phase transition between Sc-I and H-G Sc-II phases is fully reconstructive in nature. Above 62.5 GPa, the pressure will further destabilize the face-centered tetragonal (fct, Sc-IIa) guest structure to a body-centered tetragonal phase (bct, Sc-IIb), while sustaining the host structure. The structural transition mechanism of this work will shed light on the nature of the complex H-G structural modifications in compressed metals.

Different effects of scopolamine on the retrieval of spatial memory and fear memory.

Retrieval of memory is fundamental for our life as individuals. The participation of cholinergic system in memory consolidation process has been extensively studied, but there are few data concerning the function of this system in memory retrieval process. In the current study, we inject non-selective muscarinic antagonist scopolamine peripherally 20 min before training or testing to see whether cholinergic modulation has effects on the acquisition or retrieval of spatial memory by water maze task and fear memory by inhibitory avoidance task. We find that the cholinergic system is essential for the acquisition of both spatial memory and fear memory. As for the memory retrieval, the cholinergic system has a positive role in the retrieval of spatial memory, because mice injected with scopolamine 20 min before the testing in the water maze show impaired spatial memory retrieval. Whereas injection of scopolamine 20 min before the testing in the inhibitory avoidance task does not cause memory retrieval deficits. That indicates the cholinergic system is not essential for the retrieval of fear memory.

Brainstem Hap1-Ahi1 is involved in insulin-mediated feeding control.

The function of the brainstem Hap1-Ahi1 complex in the regulation of feeding behavior was investigated. When mice were fasted or treated with 2-deoxy-D-glucose (2-DG), Hap1-Ahi1 was significantly upregulated. By using streptozotocin (STZ) to decrease the circulating insulin in mice, Hap1-Ahi1 was significantly increased. Furthermore, intra-brain injection of insulin decreased the expression of Hap1-Ahi1 in the brainstem. Moreover, when we knocked down the expression of brainstem Hap1 by RNAi, the mice showed decreased food intake and lower body weights. Collectively, our results indicate that the Hap1-Ahi1 complex in the brainstem works as a sensor for insulin signals in feeding control.

Interleukin-1ß with learning and memory.

Interleukin-1ß (IL-1ß) is one of the first cytokines ever described. It has long been recognized to play an important role in mediating inflammation and orchestrating the physiological and behavioral adjustments that occur during sickness. Recently, accumulating evidence has indicated that IL-1ß also adversely affects cognitive function. Nevertheless, there are also some reports showing no effects or even beneficial effects of IL-1ß on learning and memory. The relationship between IL-1ß and cognitive impairment has not been clearly elucidated. Here we reviewed the evidence of both negative and positive effects of IL-1ß on learning and memory, and the key factors that may affect the effects of IL-1ß on learning and memory were discussed.

Effects of immune activation on the retrieval of spatial memory.

OBJECTIVE: It has been shown that there are extensive interactions between the central nervous system and the immune system. The present study focused on the effects of lipopolysaccharide (LPS) on memory retrieval, to explore the interaction between immune activation and memory. METHODS: C57BL/6J mice (8 weeks old) were first trained in the Morris water maze to reach asymptotic performance. Then mice were tested 24 h after the last training session and LPS was administered (1.25 mg/kg, i.p.) 4 h prior to the testing. The retrieval of spatial memory was tested by probe trial, and the time spent in the target quadrant and the number of platform location crosses were recorded. ELISA was performed to detect interleukin-1ß (IL-1ß) protein level in the hippocampus of mice tested in the water maze. RESULTS: Although LPS induced overt sickness behavior and a significant increase in the level of IL-1ß in the hippocampus of mice, there was no significant difference in the time spent in the target quadrant or in the number of platform location crosses between LPS-treated and control groups in the probe trial testing. CONCLUSION: Immune activation induced by LPS does not impair the retrieval of spatial memory.