Calcium Activity Research Articles

Chimeric protein EWS::FLI1 drives cell proliferation in Ewing Sarcoma via aberrant expression of KCNN1/SK1 and dysregulation of calcium signaling.

Ewing sarcoma (ES) is characterized by EWS::FLI1 or EWS::ERG fusion proteins. Knowing that ion channels are involved in tumorigenesis, this work aimed to study the involvement of the KCNN1 gene, which encodes the SK1 potassium channel, in ES development. Bioinformatics analyses from databases were used to study KCNN1 expression in patients and cell lines. Molecular approaches and in vitro assays were used to study the transcriptional regulation of KCNN1 and its involvement in the regulation of ES cell proliferation. KCNN1 is overexpressed in ES patient biopsies, and its expression is inversely correlated with patient survival. EWS::FLI1, like EWS::ERG, promotes KCNN1 and SK1 expression, binding to GGAA microsatellites near the promoter of KCNN1 isoforms. KCNN1 is involved in the regulation of ES cell proliferation, with its silencing being associated with a slowing of the cell cycle, and its expression modulates membrane potential and therefore calcium flux. These results highlight that KCNN1 is a direct target of EWS::FLI1 and EWS::ERG and demonstrate that KCNN1 is involved in the regulation of intracellular calcium activity and ES cell proliferation, making it a promising therapeutic target in ES.

Relationships Between Organic Acid Metabolism and the Accumulation of Sugars and Calcium in Fruits of Cerasus humilis During Different Development Stages

Cerasus humilis fruit is known for its high acidity, surpassing that of most other fruits. The metabolism of organic acids in these fruits significantly influences sugar and calcium accumulation. However, research on this metabolic process is limited. This study investigates the organic acid metabolism and the accumulation patterns of sugars and calcium during the development of Cerasus humilis fruits. Using low−acid and high−acid varieties from Inner Mongolia, we compared organic acid components and the activity of relevant metabolic enzymes during fruit maturation. We also measured the content and proportions of various sugars and calcium forms, performing correlation analyses. Throughout the development and ripening of Cerasus humilis fruits, organic acids, sugars, and calcium exhibited consistent patterns of change across the two acidity types. Malic acid emerged as the most significant organic acid, while fructose was the primary sugar, and active calcium was the dominant calcium component. Correlation analyses indicated that malic acid and total acid positively correlated with sugar and water−soluble calcium content, negatively regulating other calcium forms. Conversely, NADP−ME, citric acid, and oxalic acid negatively correlated with sugars and water−soluble calcium, while positively affecting other calcium forms. In conclusion, the metabolism of organic acids during the development and maturation of Cerasus humilis fruits is closely linked to the accumulation of sugars and calcium. Malic acid, primarily regulated by NAD−MDH and NADP−ME, promotes the accumulation of sugars and water−soluble calcium but inhibits other calcium forms, while citric and oxalic acids inhibit sugar accumulation and promote non−water−soluble calcium forms.

Exploring fungal potential for microbial-induced calcite precipitation (MICP) in bio-cement production

IntroductionMicrobial-induced calcite precipitation (MICP) involves various microorganisms, such as bacteria, fungi, and algae. This study focuses on producing bio-cement using fungal species and selecting potential candidates isolated from alkaline soil of different regions of Punjab, namely, Majha, Malwa, and Doaba.MethodsThe selection of fungi isolates capable of bio-cement production involves several tests, including a urease assay and calcium precipitation. Isolates having high urease enzyme production and the ability to perform calcite precipitation are selected for instrumental analyses such as X-ray diffraction (XRD) and scanning electron microscopy (SEM). The isolates selected for further analysis are S1 (3) with 8.879 ± 2.94 µg/ml, S1 (18) with 8.421 ± 0.13 µg/ml, and S4 (1) with 10.057 ± 0.45 µg/ml urease activity and least free calcium ions that are 2.337 ± 0.5 µg/ml, 3.339 ± 0.5 µg/ml, and 4.074 ± 0.1 µg/ml respectively.Results and discussionCalcite precipitation is confirmed through XRD and field emission scanning electron microscopy (FESEM). XRD images showing calcite precipitation with sharp crystalline peaks for S1 (3), S1 (18), and S4 (1) are shown. The calcite precipitation is evident in the micrographs of FESEM. These combined results confirm the potential of urease-positive fungi to facilitate calcite production, which could lead to bio-cement development in future research.

Risk factors for a decrease in bone mineral density in patients with Hodgkin's lymphoma.

BACKGROUND: Osteoporosis is characterized by a discharge of bone mass, which contributes to the development of pathological fractures. Hodgkin's lymphoma can cause a violation of bone microarchitectonics. The development of Hodgkin's lymphoma is characteristic of young people, on average from 16 to 35 years old. Early diagnosis of osteoporosis in young patients with Hodgkin's lymphoma is an urgent issue due to a prolonged asymptomatic decrease in bone mineral density, with the development of pathological fractures. AIMS: to study the risk factors for a decrease in bone mineral density in patients with Hodgkin's lymphoma who received pathogenetic therapy. MATERIALS AND METHODS: the study included 63 patients with Hodgkin's lymphoma and 30 volunteers from the control group. All patients answered the questionnaire questions in order to identify risk factors for osteoporosis. Common risk factors included: gender, age, body mass index; fractures in the history of the patient and his immediate family; taking hormone replacement therapy, proton pump inhibitors, glucocorticosteroids; the presence of concomitant diseases; the presence of amenorrhea in women; physical activity level and calcium intake. Specific factors include the use of chemotherapy drugs for the treatment of Hodgkin's lymphoma. The data obtained were subjected to statistical analysis in order to identify the most significant risk factors. RESULTS: osteopenia and osteoporosis are a serious complication of antitumor therapy of Hodgkin's lymphoma in young people. Unfortunately, today a small number of researchers are engaged in the problem of identifying predictors of osteoporosis in young patients with Hodgkin's lymphoma. Because of this study, the most significant risk factors for the development of osteoporosis were identified, namely low physical activity, taking proton pump inhibitors and glucocorticosteroids, as well as the development of secondary postcytostatic amenorrhea in women. CONCLUSIONS: timely diagnosis and prevention of osteoporosis in young patients will prevent a decrease in bone mineral density and reduce the risks of early disability in this category of patients.

Distinct functional classes of CA1 hippocampal interneurons are modulated by cerebellar stimulation in a coordinated manner.

There is mounting evidence that the cerebellum impacts hippocampal functioning, but the impact of the cerebellum on hippocampal interneurons remains obscure. Using miniscopes in freely behaving male and female mice, we find optogenetic stimulation of Purkinje cells alters the calcium activity of a large percentage of CA1 interneurons. This includes both increases and decreases in activity. Remarkably, this bidirectional impact occurs in a coordinated fashion, in line with interneurons' functional properties. Specifically, CA1 interneurons activated by cerebellar stimulation are commonly locomotion-active, while those inhibited by cerebellar stimulation are commonly rest-active interneurons. We additionally find that subsets of CA1 interneurons show altered activity during object investigations. Importantly, these interneurons also show coordinated modulation by cerebellar stimulation: CA1 interneurons that are activated by cerebellar stimulation are more likely to be activated, rather than inhibited, during object investigations, while interneurons that show decreased activity during cerebellar stimulation show the opposite profile. We examined two different stimulation locations (IV/V Vermis or Simplex) and two different stimulation approaches (7Hz or a single 1s light pulse) - in all cases, the cerebellum induces similar coordinated CA1 interneuron changes congruent with an explorative state. Overall, our data show that CA1 interneurons are impacted by cerebellar manipulation in a bidirectional and coordinated fashion, and are therefore likely to play an important role in cerebello-hippocampal communication.Significance Statement Acute manipulation of the cerebellum can affect the activity of cells in CA1, and perturbing normal cerebellar functioning can affect hippocampal-dependent spatial processing, including the processing of objects in space. Despite the importance of interneurons on the local hippocampal circuit, it was unknown how cerebellar activation impacts CA1 inhibitory neurons. We find that stimulating the cerebellum robustly affects multiple populations of CA1 interneurons in a bidirectional, coordinated manner, according to their functional profiles during behavior, including locomotion and object investigations.

Integration of single-photon miniature fluorescence microscopy and electrophysiological recording methods for <i>in vivo</i> studying hippocampal neuronal activity

The miniature single-photon fluorescent microscope (miniscope) enables the visualization of calcium activity in vivo in freely moving laboratory animals, providing the capability to track cellular activity during the investigation of memory formation, learning, sleep, and social interactions. However, the use of calcium sensors for in vivo imaging is limited by their relatively slow (millisecond-scale) kinetics, which complicates the recording of high-frequency spike activity. The integration of methods from single-photon miniature fluorescent microscopy with electrophysiological recording, which possesses microsecond resolution, represents a potential solution to this issue. Such a combination of techniques allows for the simultaneous recording of optical and electrophysiological activity in a single animal in vivo. In this study, a flexible polyimide microelectrode was developed and integrated with the gradient lens of the miniscope. The in vivo tests conducted in this research confirmed that the microelectrode combined with the gradient lens facilitates simultaneous single-photon calcium imaging and local field potential recording in the hippocampus of an adult mouse.

A Tympanic Piezo-Bioreactor Modulates Ion Channel-Associated Mechanosignaling to Stabilize Phenotype and Promote Tenogenesis in Human Tendon-Derived Cells.

Preserving the function of human tendon-derived cells (hTDCs) during cell expansion is a significant challenge in regenerative medicine. In this study, a non-genetic approach is introduced to control the differentiation of hTDCs using a newly developed tympanic bioreactor. The system mimics the functionality of the human tympanic membrane, employing a piezoelectrically tuned acoustic diaphragm made of polyvinylidene fluoride-co-trifluoroethylene and boron nitride nanotubes. The diaphragm is vibrationally actuated to deliver targeted electromechanical stimulation to hTDCs. The results demonstrate that the system effectively maintains the tendon-specific phenotype of hTDCs, even under conditions that typically induce nonspecific differentiation, such as osteogenesis. This stabilization is achieved by modulating integrin-mediated mechanosignaling via ion channel-regulated calcium activity, potentially by TREK-1 and PIEZO1, yet targeted studies are required for confirmation. Finally, the system sustains the activation of key differentiation pathways (bone morphogenetic protein, BMP) while downregulating osteogenesis-associated (mitogen-ctivated protein kinase, MAPK and wingless integrated, WNT) pathways and upregulating Focal Adhesion Kinase (FAK) signaling. This approach offers a finely tunable, dose-dependent control over hTDC differentiation, presenting significant potential for non-genetic approaches in cell therapy, tendon tissue engineering, and the regeneration of other mechanosensitive tissues.

On the rate-limiting dynamics of force development in muscle.

Skeletal muscles produce forces relatively slowly compared with the action potentials that excite them. The dynamics of force production are governed by multiple processes, such as calcium activation, cycling of cross-bridges between myofilaments, and contraction against elastic tissues and the body. These processes have been included piecemeal in some muscle models, but not integrated to reveal which are the most rate limiting. We therefore examined their integrative contributions to force development in two conventional types of muscle models: Hill-type and cross-bridge. We found that no combination of these processes can self-consistently reproduce classic data such as twitch and tetanus. Rather, additional dynamics are needed following calcium activation and facilitating cross-bridge cycling, such as for cooperative myofilament interaction and reconfiguration. We provisionally lump such processes into a simple first-order model of 'force facilitation dynamics' that integrate into a cross-bridge-type muscle model. The proposed model self-consistently reproduces force development for a range of excitations including twitch and tetanus and electromyography-to-force curves. The model's step response reveals relatively small timing contributions of calcium activation (3%), cross-bridge cycling (3%) and contraction (27%) to overall force development of human quadriceps, with the remainder (67%) explained by force facilitation. The same set of model parameters predicts the change in force magnitude (gain) and timing (phase delay) as a function of excitatory firing rate, or as a function of cyclic contraction frequency. Although experiments are necessary to reveal the dynamics of muscle, integrative models are useful for identifying the main rate-limiting processes.

Time-Dependent Electrical Active and Ultrasound-Responsive Calcium Titanate Implant Coating with Immunomodulation, Osteogenesis, and Customized Antibacterial Activity.

Surgical site infection and insufficient osseointegration are notable risks factors associated with oral implant surgery. In this study, the development of a polarized calcium titanate (CT-P) coating for titanium surfaces is proposed as a solution to these problems. The coating generated electrical stimulation (ES) can inhibit pro-inflammatory M1-type macrophage polarization and promote anti-inflammatory M2-type macrophage polarization, resulting in favorable bone immunomodulation. The ES generated by the coating can match the physiological electrical potential that will change during bone repair, thereby promoting osseointegration in vivo. In addition, the system can also achieve on-demand antibacterial activity, mainly depending on the CT-P coating responding to ultrasound (US) irradiation to produce reactive oxygen species (ROS) and remove Staphylococcus aureus (S. aureus) on the surface of the implant. In conclusion, this work provides valuable insights for the development and clinical application of highly efficient electroactive coatings, as well as novel solutions for the selective treatment of bacterial infections in the surgical area.

Sex differences in prelimbic cortex calcium dynamics during stress and fear learning

In recent years, research has progressively increased the importance of considering sex differences in stress and fear memory studies. Many studies have traditionally focused on male subjects, potentially overlooking critical differences with females. Emerging evidence suggests that males and females can exhibit distinct behavioral and neurophysiological responses to stress and fear conditioning. These differences may be attributable to variations in hormone levels, brain structure, and neural circuitry, particularly in regions such as the prefrontal cortex (PFC). In the present study, we explored sex differences in prelimbic cortex (PL) calcium activity in animals submitted to immobilization stress (IMO), fear conditioning (FC), and fear extinction (FE). While no significant sex differences were found in behavioral responses, we did observe differences in several PL calcium activity parameters. To determine whether these results were related to behaviors beyond stress and fear memory, we conducted correlation studies between the movement of the animals and PL activity during IMO and freezing behavior during FC and FE. Our findings revealed a clear correlation between PL calcium activity with movement during stress exposure and freezing behavior, with no sex differences observed in these correlations. These results suggest a significant role for the PL in movement and locomotion, in addition to its involvement in fear-related processes. The inclusion of both female and male subjects is crucial for studies like this to fully understand the role of the PFC and other brain areas in stress and fear responses. Recognizing sex differences enhances our comprehension of brain function and can lead to more personalized and effective approaches in the study and treatment of stress and fear-related conditions.

Astrocytes in the rostral ventromedial medulla mediate the analgesic effect of electroacupuncture in a rodent model of chemotherapy-induced peripheral neuropathic pain.

Chemotherapy-induced peripheral neuropathic pain aggravates cancer survivors' life burden. Electroacupuncture (EA) has exhibited promising analgesic effects on neuropathic pain in previous studies. We investigated whether EA was effective in a paclitaxel-induced neuropathic pain mouse model. We further explored the functional role of astrocytes in the rostral ventromedial medulla (RVM), a well-established pain modulation center, in the process of neuropathic pain as well as the analgesic effect of EA. We found that paclitaxel induced mechanical allodynia, astrocytic calcium signaling, and neuronal activation in the RVM and spinal cord, which could be suppressed by EA treatment. Electroacupuncture effectively alleviated paclitaxel-induced mechanical allodynia, and the effect was attenuated by the chemogenetic activation of astrocytes in the RVM. In addition, inhibiting astrocytic calcium activity by using either IP3R2 knockout (IP3R2 KO) mice or microinjection of AAV-mediated hPMCA2 w/b into the RVM to reduce non-IP3R2-dependent Ca2+ signaling in astrocytes exhibited an analgesic effect on neuropathic pain, which mimicked the EA effect. The current study revealed the pivotal role of the RVM astrocytes in mediating the analgesic effects of EA on chemotherapy-induced peripheral neuropathic pain.

Effects of ketamine on GABAergic and glutamatergic activity in the mPFC: biphasic recruitment of GABA function in antidepressant-like responses.

Major depressive disorder (MDD) is associated with disruptions in glutamatergic and GABAergic activity in the medial prefrontal cortex (mPFC), leading to altered synaptic formation and function. Low doses of ketamine rapidly rescue these deficits, inducing fast and sustained antidepressant effects. While it is suggested that ketamine produces a rapid glutamatergic enhancement in the mPFC, the temporal dynamics and the involvement of GABA interneurons in its sustained effects remain unclear. Using simultaneous photometry recordings of calcium activity in mPFC pyramidal and GABA neurons, as well as chemogenetic approaches in Gad1-Cre mice, we explored the hypothesis that initial effects of ketamine on glutamate signaling trigger subsequent enhancement of GABAergic responses, contributing to its sustained antidepressant responses. Calcium recordings revealed a biphasic effect of ketamine on activity of mPFC GABA neurons, characterized by an initial transient decrease (phase 1, <30 min) followed by an increase (phase 2, >60 min), in parallel with a transient increase in excitation/inhibition levels (10 min) and lasting enhancement of glutamatergic activity (30-120 min). Previous administration of ketamine enhanced GABA neuron activity during the sucrose splash test (SUST) and novelty suppressed feeding test (NSFT), 24 h and 72 h post-treatment, respectively. Chemogenetic inhibition of GABA interneurons during the surge of GABAergic activity (phase 2), or immediately before the SUST or NSFT, occluded ketamine's behavioral actions. These results indicate that time-dependent modulation of GABAergic activity is required for the sustained antidepressant-like responses induced by ketamine, suggesting that approaches to enhance GABAergic plasticity and function are promising therapeutic targets for antidepressant development.

Cochlear implant/MXene-based electroacoustic stimulation modulates the growth and maturation of spiral ganglion neurons

Cochlear implantation (CI) offers a dependable treatment for sensorineural hearing loss, with precision electroacoustic stimulation parameters showing great potential in improving auditory outcomes in CI patients. Here, we report the attachment of MXene into CI systems which effectively mimic the neural electrode interface due to MXene's excellent electrical conductivity and biocompatibility. Low-frequency short-term biphasic electrical pulses emitted by the MXenes-based CI promoted the outgrowth of spiral ganglion neuron (SGN) neurites and growth cones, substantially boosting the calcium activity in SGNs. This study lays a theoretical foundation for the precision medicine approaches in CI patient care, and informs the selection of materials for cochlear implant electrode materials in the future.

Selective Modulation of Fear Memory in Non-Rapid Eye Movement Sleep.

Sleep stabilizes memories for their consolidation, but how to modify specific fear memory during sleep remains unclear. Here, it is reported that using targeted memory reactivation (TMR) to reactivate prior fear learning experience in non-slow wave sleep (NS) inhibits fear memory consolidation, while TMR during slow wave sleep (SWS) enhances fear memory in mice. Replaying conditioned stimulus (CS) during sleep affects sleep spindle occurrence, leading to the reduction or enhancement of slow oscillation-spindle (SO-spindle) coupling in NS and SWS, respectively. Optogenetic inhibition of pyramidal neurons in the frontal association cortex (FrA) during TMR abolishes the behavioral effects of NS-TMR and SWS-TMR by modulating SO-spindle coupling. Notably, calcium imaging of the L2/3 pyramidal neurons in the FrA shows that CS during SWS selectively enhances the activity of neurons previously activated during fear conditioning (FC+ neurons), which significantly correlates with CS-elicited spindle power spectrum density. Intriguingly, these TMR-induced calcium activity changes of FC+ neurons further correlate with mice freezing behavior, suggesting their contributions to the consolidation of fear memories. The findings indicate that TMR can selectively weaken or strengthen fear memory, in correlation with modulating SO-spindle coupling and the reactivation of FC+ neurons during substages of non-rapid eye movement (NREM) sleep.

Reward and punishment contingency shifting reveals distinct roles for VTA dopamine and GABA neurons in behavioral flexibility.

In dynamic environments where stimuli predicting rewarding or aversive outcomes unexpectedly change, it is critical to flexibly update behavior while preserving recollection of previous associations. Dopamine and GABA neurons in the ventral tegmental area (VTA) are implicated in reward and punishment learning, yet little is known about how each population adapts when the predicted outcome valence changes. We measured VTA dopamine and GABA population activity while male and female rats learned to associate three discrete auditory cues to three distinct outcomes: reward, punishment, or no outcome within the same session. After learning, the reward and punishment cue-outcome contingencies were reversed, and subsequently rereversed. As expected, the dopamine population rapidly adapted to learning and contingency reversals by increasing the response to appetitive stimuli and decreasing the response to aversive stimuli. In contrast, the GABA population increased activity to all sensory events regardless of valence, including the neutral cue. Reversing learned contingencies selectively influenced GABA responses to the reward-predictive cue, prolonging increased activity within and across sessions. The observed valence-specific dissociations in the directionality and temporal progression of VTA dopamine and GABA calcium activity indicates that these populations are independently recruited and serve distinct roles during appetitive and aversive associative learning and contingency reversal.

Electrophysical cardiac remodeling at the molecular level: Insights into ryanodine receptor activation and calcium-induced calcium release from a stochastic explicit-particle model

We present the first-ever, fully discrete, stochastic model of triggered cardiac calcium dynamics. Using anatomically accurate subcellular cardiac myocyte geometries, we simulate the molecular players involved in calcium handling using high-resolution stochastic and explicit-particle methods at the level of an individual cardiac dyadic junction. Integrating data from multiple experimental sources, the model not only replicates the findings of traditional in silico studies and complements in vitro experimental data but also reveals new insights into the molecular mechanisms driving cardiac dysfunction under stress and disease conditions. We improve upon older, nondiscrete models using the same realistic geometry by incorporating molecular mechanisms for spontaneous, as well as triggered calcium-induced calcium release (CICR). Action potentials are used to activate L-type calcium channels, triggering CICR through ryanodine receptors (RyRs) on the surface of the sarcoplasmic reticulum. These improvements allow for the specific focus on the couplon: the structure-function relationship between L-type calcium channel and RyR. We investigate the electrophysical effects of normal and diseased action potentials on CICR and interrogate the effects of dyadic junction deformation through detubulation and orphaning of RyR. Our work demonstrates the importance of the electrophysical integrity of the calcium release unit on CICR fidelity, giving insights into the molecular basis of heart disease. Finally, we provide a unique, detailed, molecular view of the CICR process using advanced rendering techniques. This easy-to-use model comes complete with tutorials and all necessary software for use and analysis so as to maximize usability and reproducibility. Our work focuses on quantifying, qualifying, and visualizing the behavior of the molecular species that underlie the function and dysfunction of subcellular cardiomyocyte systems.

Evaluation of calcium looping CO2 capture and thermochemical energy storage performances of different stabilizers promoted CaO-based composites derived from solid wastes

Calcium looping is considered as an important high-temperature cyclic CO2 capture and concentrated solar energy storage technology. However, the dramatic inactivation of CaO over multiple carbonation-calcination cycles has seriously restricted their practical applications. In this study, a series of metal oxide (i.e. TiO2, MgO, Al2O3 and ZrO2)-stabilized CaO-based materials with high cyclic stability derived from carbide slag were synthesized via a facile and cost-effective approach for simultaneously enhanced CO2 capture and thermochemical energy storage (TCES). The results suggest that CCS-H-TiO2 exhibits high initial CO2 uptake of 0.41 gCO2/gsorbent, superior cyclic stability with an average attenuation of 1.71 %/cycle and remarkably stable energy storage density. CCS-H-Al2O3 shows the best stability with lowest attenuation rate of 9.6 %. Except for CCS-H-MgO, the stabilizers reacted with active calcium to form new phases and used as physical “barrier” and high-TT skeleton to offset the sintering stress, retain the microporous structures, hinder the excessive agglomeration and alleviate sintering.

Dynamic changes of media prefrontal cortex astrocytic activity in response to negative stimuli in male mice

Astrocytes play significant roles in regulating the central stress response. Chronic stress impairs the structure and function of astrocytes in many brain regions such as media prefrontal cortex (mPFC) in multiple neuropsychiatric conditions, but the astrocytic dynamics on the timescale of behavior remains unclear. Here, we recorded mPFC astrocytic activity in freely behaving mice and found that astrocytes are activated immediately by different aversive stimuli. Astrocyte specific GCaMP6s calcium indicator were virally expressed in mPFC astrocytes and fiber photometry experiments revealed that astrocytes are activated by tail-restraint (TRT), foot shock (FS), open arm exploration, stressor of height, predator odor and social defeat (SD) stress. ΔF/F analyses demonstrated that an unpredictable stimulus such as elevated platform stress (EPS) at the initial encounter induced the most intense and rapid changes in astrocytic calcium activity, while a predictable 2,5-dihydro-2,4,5-trimethylthiazoline (TMT) stimulus resulted in the weakest response with a longer peak latency. In TRT, FS or SD test, a somatic stimulus led to higher average calcium activity level and faster average peak latency in repeated trails. Similar to TMT stimulus, astrocytic calcium activity in elevated plus maze (EPM) test exhibited a smaller average change in amplitude and the longest peak latency during open arm exploration. Moreover, astrocytic calcium activity exhibited different changes across behavioral states in SD tests. Our findings show that mPFC astrocytes exhibit distinct patterns of calcium activity in response to various negative stimuli, indicating that the dynamic activity of astrocytes may reflect the stress-related behavioral state under different stimulus conditions.

Terminal differentiation precedes functional circuit integration in the peduncle neurons in regenerating Hydra vulgaris

Understanding how neural circuits are regenerated following injury is a fundamental question in neuroscience. Hydra is a powerful model for studying this process because it has a simple neural circuit structure, significant and reproducible regenerative abilities, and established methods for creating transgenics with cell-type-specific expression. While Hydra is a long-standing model for regeneration and development, little is known about how neural activity and behavior is restored following significant injury. In this study, we ask if regenerating neurons terminally differentiate prior to reforming functional neural circuits, or if neural circuits regenerate first and then guide the constituent naive cells toward their terminal fate. To address this question, we developed a dual-expression transgenic Hydra line that expresses a cell-type-specific red fluorescent protein (tdTomato) in ec5 peduncle neurons, and a calcium indicator (GCaMP7s) in all neurons. With this transgenic line, we can simultaneously record neural activity and track the reappearance of the terminally-differentiated ec5 neurons. Using SCAPE (Swept Confocally Aligned Planar Excitation) microscopy, we monitored both calcium activity and expression of tdTomato-positive neurons in 3D with single-cell resolution during regeneration of Hydra’s aboral end. The synchronized neural activity associated with a regenerated neural circuit was observed approximately 4 to 8 hours after expression of tdTomato in ec5 neurons. These data suggest that regenerating ec5 neurons undergo terminal differentiation prior to re-establishing their functional role in the nervous system. The combination of dynamic imaging of neural activity and gene expression during regeneration make Hydra a powerful model system for understanding the key molecular and functional processes involved in neural regeneration following injury.

Mechanical property and microstructure of fly ash-based geopolymer by calcium activators

Geopolymer is a green and environmentally friendly new type of gel material generated from the reaction of activators with silica-alumina raw materials, possessing extensive research and application value. Fly ash can be used as reaction material, enabling the industrial solid waste to be recycled and reused. In this paper, unconfined compressive strength test, X-ray diffraction analysis, Fourier transform infrared light, 29Si nuclear magnetic resonance, scanning electron microscope and energy disperse spectroscopy, and physisorption experiment were carried out to study the effects of the type and dosage on the mechanical property and microstructure of fly ash-based geopolymer activated by calcium hydroxide, calcium sulfate and their compound. The results indicated that calcium hydroxide and calcium sulfate can promote the dissolution of fly ash crystals, providing adequate Ca2+ for the formation of gel products. The products of calcium hydroxide and calcium sulfate activation are hydrated calcium aluminate, hydrated calcium sulfate, and ettringite, respectively. The effect of the compound activator is superior to that of single activators. With the increase of the proportion of calcium hydroxide, the reorganization and polymerization of gel products were accelerated so that the integrity and continuity of the microstructure of geopolymer were improved, and then the strength increased. When the ratio of calcium hydroxide to calcium sulfate was 3:1 and the total dosage was 20 %, the unconfined compressive strength reached the maximum value. According to this study, it was investigated that type and dosage of calcium activators had evident influence on the geopolymerization of fly ash. And the reutilization and resource utilization of fly ash waste can be achieved, which can provide an engineering theoretical basis for using fly ash-based geopolymer to alter the physical and chemical properties of special soils and achieve solidification effect.