Soil seed banks along elevational gradients in tropical, subtropical and subalpine forests in Yunnan Province, southwest China

Soil seed banks are a vital part of ecosystems and influence community dynamics and regeneration. Although soil seed banks in different habitats have been reported, how soil seed banks vary with elevational gradients in different climatic zones is still unknown. This paper investigates seed density, species composition and nonconstituent species of forest soil seed banks in Yunnan Province, southwest China. Similarity between the soil seed bank and standing vegetation was also examined. We collected soil samples from sites spanning 12 elevations in tropical rain forests, subtropical evergreen broad-leaved forests and subalpine coniferous forests, and transported them to a glasshouse for germination trials for species identification. The soil seed banks of tropical and subtropical forests had much higher seed densities and species richness than those of subalpine forests. Seeds of woody species dominated the soil seed banks of tropical and subtropical forests, while herbs dominated those of subalpine forests. The nonconstituent species in the soil seed banks were all herbs and were most abundant in tropical forests, followed by subtropical forests but were completely absent from subalpine forests

Impact of closed management on gastrointestinal function and mental health of Chinese university students during COVID-19

Abstract Background The innovative closed management of universities may have influenced the physical and mental health of students during the fourth stage of the COVID-19 pandemic in China. The study aimed to assess the gastrointestinal and mental health status of students in this stage and to explore the possible risk factors and mechanisms to provide a reference for future school responses to similar stressful events. Method A multicenter, cross-sectional survey was administered to 598 college students from 10 Chinese universities. The study used the 7-item Generalized Anxiety Disorder Scale (GAD-7), 9-item Patient Health Questionnaire (PHQ-9), Fear of COVID-19 Scale (FCV-19 S), and the Diagnostic Tendency of Functional Bowel Disease Scale (DT-FBD) to evaluate anxiety, depression, fear of COVID-19 and likelihood of being diagnose diagnosed with functional bowel disease (FBD), respectively. Results A total of 516 college students completed the questionnaire. The proportions of students with more severe anxiety, more severe depression, greater fear of COVID-19, and a greater likelihood of being diagnosed with FBD were 49.8%, 57.0%, 49%, and 49%, respectively. These symptoms were significantly and positively correlated with the frequency of irregular sleep and eating (p < 0.05). Students in high-risk areas were more likely to experience anxiety and depression than students in areas with low/medium risk (odds ratio [OR] = 1.90, 95% confidence interval [CI]: 1.12–3.24, p = 0.017; OR = 2.14, 95% CI: 1.11–4.11, p = 0.022). A high likelihood of being diagnosed with FBD was positively associated with the severity of anxiety and depression symptoms and fear of COVID-19 (all p < 0.001). Moreover, mediation analysis revealed the following pathway in college students: fear of COVID-19 → depression and anxiety → poor diet → likelihood of being diagnosed with FBD. Conclusion College students generally exhibited higher more severe anxiety and depression symptoms and psychological symptoms with a greater higher propensity likelihood of being to be diagnosed with FBD. Good lifestyle habits, especially adequate sleep and a regular diet, can alleviate these problems. In addition, appropriate psychological intervention is very important

GABA Attenuates Amyloid Toxicity by Downregulating its Endocytosis and Improves Cognitive Impairment

GABA (gamma-aminobutyric acid) receptor modulators have been investigated as a potential treatment strategy in Alzheimer's disease (AD). In the present study, we found that GABA levels were different in wild type (WT) and A beta PP/PS1 mouse brains. GABA downregulated amyloid-beta (A beta) uptake in neurons through the receptor for advanced glycation end-products. Therefore, relative high levels of GABA decreased cytotoxicity induced by A beta in WT mice. GABA treatment decreased basal levels of cell death and the cell death induced by hydrogen peroxide in WT and A beta PP/PS1 neurons. Application of GABA during early life before 2 months of age can improve cognitive function significantly in A beta PP/PS1 mice. However, GABA treatment at 6 and 8 months of age cannot improve water maze performance. Activating or suppressing GABA(A) receptors by optogenetic methods also confirmed that GABA activation before 2 months of age increased water maze performance in A beta PP/PS1 mice. Our data suggest that GABA administration during early life can be a potential treatment for AD

HIV Replication and Latency in a Humanized NSG Mouse Model during Suppressive Oral Combinational Antiretroviral Therapy.

Although current combinatorial antiretroviral therapy (cART) is therapeutically effective in the majority of HIV patients, interruption of therapy can cause a rapid rebound in viremia, demonstrating the existence of a stable reservoir of latently infected cells. HIV latency is therefore considered a primary barrier to HIV eradication. Identifying, quantifying, and purging the HIV reservoir is crucial to effectively curing patients and relieving them from the lifelong requirement for therapy. Latently infected transformed cell models have been used to investigate HIV latency; however, these models cannot accurately represent the quiescent cellular environment of primary latently infected cells in vivo For this reason, in vivo humanized murine models have been developed for screening antiviral agents, identifying latently infected T cells, and establishing treatment approaches for HIV research. Such models include humanized bone marrow/liver/thymus mice and SCID-hu-thy/liv mice, which are repopulated with human immune cells and implanted human tissues through laborious surgical manipulation. However, no one has utilized the human hematopoietic stem cell-engrafted NOD/SCID/IL2rγnull (NSG) model (hu-NSG) for this purpose. Therefore, in the present study, we used the HIV-infected hu-NSG mouse to recapitulate the key aspects of HIV infection and pathogenesis in vivo Moreover, we evaluated the ability of HIV-infected human cells isolated from HIV-infected hu-NSG mice on suppressive cART to act as a latent HIV reservoir. Our results demonstrate that the hu-NSG model is an effective surgery-free in vivo system in which to efficiently evaluate HIV replication, antiretroviral therapy, latency and persistence, and eradication interventions.IMPORTANCE HIV can establish a stably integrated, nonproductive state of infection at the level of individual cells, known as HIV latency, which is considered a primary barrier to curing HIV. A complete understanding of the establishment and role of HIV latency in vivo would greatly enhance attempts to develop novel HIV purging strategies. An ideal animal model for this purpose should be easy to work with, should have a shortened disease course so that efficacy testing can be completed in a reasonable time, and should have immune correlates that are easily translatable to humans. We therefore describe a novel application of the hematopoietic stem cell-transplanted humanized NSG model for dynamically testing antiretroviral treatment, supporting HIV infection, establishing HIV latency in vivo The hu-NSG model could be a facile alternative to humanized bone marrow/liver/thymus or SCID-hu-thy/liv mice in which laborious surgical manipulation and time-consuming human cell reconstitution is required

HIV Replication and Latency in a Humanized NSG Mouse Model during Suppressive Oral Combinational Antiretroviral Therapy

Although current combinatorial antiretroviral therapy (cART) is therapeutically effective in the majority of HIV patients, interruption of therapy can cause a rapid rebound in viremia, demonstrating the existence of a stable reservoir of latently infected cells. HIV latency is therefore considered a primary barrier to HIV eradication. Identifying, quantifying, and purging the HIV reservoir is crucial to effectively curing patients and relieving them from the lifelong requirement for therapy. Latently infected transformed cell models have been used to investigate HIV latency; however, these models cannot accurately represent the quiescent cellular environment of primary latently infected cells in vivo For this reason, in vivo humanized murine models have been developed for screening antiviral agents, identifying latently infected T cells, and establishing treatment approaches for HIV research. Such models include humanized bone marrow/liver/thymus mice and SCID-hu-thy/liv mice, which are repopulated with human immune cells and implanted human tissues through laborious surgical manipulation. However, no one has utilized the human hematopoietic stem cell-engrafted NOD/SCID/IL2rγnull (NSG) model (hu-NSG) for this purpose. Therefore, in the present study, we used the HIV-infected hu-NSG mouse to recapitulate the key aspects of HIV infection and pathogenesis in vivo Moreover, we evaluated the ability of HIV-infected human cells isolated from HIV-infected hu-NSG mice on suppressive cART to act as a latent HIV reservoir. Our results demonstrate that the hu-NSG model is an effective surgery-free in vivo system in which to efficiently evaluate HIV replication, antiretroviral therapy, latency and persistence, and eradication interventions.IMPORTANCE HIV can establish a stably integrated, nonproductive state of infection at the level of individual cells, known as HIV latency, which is considered a primary barrier to curing HIV. A complete understanding of the establishment and role of HIV latency in vivo would greatly enhance attempts to develop novel HIV purging strategies. An ideal animal model for this purpose should be easy to work with, should have a shortened disease course so that efficacy testing can be completed in a reasonable time, and should have immune correlates that are easily translatable to humans. We therefore describe a novel application of the hematopoietic stem cell-transplanted humanized NSG model for dynamically testing antiretroviral treatment, supporting HIV infection, establishing HIV latency in vivo The hu-NSG model could be a facile alternative to humanized bone marrow/liver/thymus or SCID-hu-thy/liv mice in which laborious surgical manipulation and time-consuming human cell reconstitution is required

Preferential Regulation of Γ‐Secretase‐Mediated Cleavage of APP by Ganglioside GM1 Reveals a Potential Therapeutic Target for Alzheimer's Disease

Abstract A hallmark of Alzheimer's disease (AD) is the senile plaque, which contains β‐amyloid peptides (Aβ). Ganglioside GM1 is the most common brain ganglioside. However, the mechanism of GM1 in modulating Aβ processing is rarely known. Aβ levels are detected by using Immunohistochemistry (IHC) and enzyme‐linked immune‐sorbent assay (ELISA). Cryo‐electron microscopy (Cryo‐EM) is used to determine the structure of γ‐secretase supplemented with GM1. The levels of the cleavage of amyloid precursor protein (APP)/Cadherin/Notch1 are detected using Western blot analysis. Y maze, object translocation, and Barnes maze are performed to evaluate cognitive functions. GM1 leads to conformational change of γ‐secretase structure and specifically accelerates γ‐secretase cleavage of APP without affecting other substrates including Notch1, potentially through its interaction with the N‐terminal fragment of presenilin 1 (PS1). Reduction of GM1 levels decreases amyloid plaque deposition and improves cognitive dysfunction. This study reveals the mechanism of GM1 in Aβ generation and provides the evidence that decreasing GM1 levels represents a potential strategy in AD treatment. These results provide insights into the detailed mechanism of the effect of GM1 on PS1, representing a step toward the characterization of its novel role in the modulation of γ‐secretase activity and the pathogenesis of AD