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41.
Immunocytochemical localization of the epidermal growth factor receptor in mouse testis 总被引:5,自引:0,他引:5
The distribution of the epidermal growth factor receptor (EGFR) in mouse testis was ascertained by immunocytochemical methodology using a polyclonal antibody (RK2) shown previously to recognize the cytoplasmic domain of the human (A431 cells), murine (Swiss 3T3 cells), and chicken (CK 109 cells) EGFR. Initial studies performed to determine the usefulness of this antibody as a probe of the murine EGFR in testis employed two murine cell lines, TM4 and MA10, of Sertoli cell and Leydig cell origin, respectively, in which a physiological response of EGF and specific binding of iodinated EGF has been demonstrated. Western blotting in membrane preparations of TM4 and MA10 revealed only one prominent band at 170 kDa. Immunocytochemical localization in TM4 and MA10 cells illustrated a plasma membrane distribution of the receptor. Western blotting of membrane fractions prepared from testis also revealed a specific band at 170 kDa. In the intact testis, the EGFR was immunolocalized specifically in Leydig cells and Sertoli cells only. These results suggest that the involvement of EGF action in spermatogenesis may occur at the level of the somatic components of the testes, principally in the Leydig and Sertoli cells. 相似文献
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Identifying the mechanisms that underlie the assembly of plant communities is critical to the conservation of terrestrial biodiversity. However, it is seldom measured or quantified how much deterministic versus stochastic processes contribute to community assembly in alpine meadows. Here, we measured the decay in community similarity with spatial and environmental distance in the Zoige Plateau. Furthermore, we used redundancy analysis (RDA) to divide the variations in the relative abundance of plant families into four components to assess the effects of environmental and spatial. Species assemblage similarity liner declined with geographical distance (p < .001, R 2 = .6388), and it decreased significantly with increasing distance of total phosphorus (TP), alkali‐hydrolyzable nitrogen (AN), available potassium (AK), nitrate nitrogen (NO3 +–N), and ammonia nitrogen (NH4 +–N). Environmental and spatial variables jointly explained a large proportion (55.2%) of the variation in the relative abundance of plant families. Environmental variables accounted for 13.1% of the total variation, whereas spatial variables accounted for 11.4%, perhaps due to the pronounced abiotic gradients in the alpine areas. Our study highlights the mechanism of plant community assembly in the alpine ecosystem, where environmental filtering plays a more important role than dispersal limitation. In addition, a reasonably controlled abundance of Compositae (the family with the highest niche breadth and large niche overlap value with Gramineae and Cyperaceae) was expected to maintain sustainable development in pastoral production. These results suggest that management measures should be developed with the goal of improving or maintaining suitable local environmental conditions. 相似文献
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Jianping Hu Yiting Zhang Shenglan Yi Chaokui Wang Xinyue Huang Su Pan Jinglu Yang Gangxiang Yuan Sisi Tan Hong Li 《International journal of biological sciences》2022,18(11):4545
Dendritic cells (DCs) are the major antigen-presenting cells and play an important role in autoimmune uveitis. Emerging evidence suggests that bile acids (BAs) regulate DCs maturation. However, the underlying mechanisms by which BAs regulate the function of DCs still need to be clarified. Here, we demonstrate that lithocholic acid (LCA) inhibits the production of pro-inflammatory cytokines and the expression of surface molecules in bone marrow-derived dendritic cells (BMDCs). LCA attenuates the severity of EAU by modulating the maturation of splenic CD11C+MHCIIhigh DCs. Notably, Takeda G-protein coupled receptor 5 (TGR5) deficiency partially reverses the inhibitory effect of LCA on DCs in vitro and in vivo. TGR5 activation also downregulates the NF-κB and MAPK pathways by inhibiting glutathione production and inducing oxidative stress in DCs, which leads to apoptosis and autophagy in DCs. In addition, LCA or INT-777 treatment increases the TGR5 expression in monocyte-derived dendritic cells (MD-DCs) of patients with active BD, whereas both LCA and TGR5 agonists inhibit the activation of MD-DCs. These results suggest that LCA and TGR5 agonists might be potential therapeutic drugs for the treatment of autoimmune uveitis. 相似文献
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Chen Chen John Wang Jeff Kwong JinHee Kim Aaron van Donkelaar Randall V. Martin Perry Hystad Yushan Su Eric Lavigne Megan Kirby-McGregor Jay S. Kaufman Tarik Benmarhnia Hong Chen 《CMAJ》2022,194(20):E693
Background:The tremendous global health burden related to COVID-19 means that identifying determinants of COVID-19 severity is important for prevention and intervention. We aimed to explore long-term exposure to ambient air pollution as a potential contributor to COVID-19 severity, given its known impact on the respiratory system.Methods:We used a cohort of all people with confirmed SARS-CoV-2 infection, aged 20 years and older and not residing in a long-term care facility in Ontario, Canada, during 2020. We evaluated the association between long-term exposure to fine particulate matter (PM2.5), nitrogen dioxide (NO2) and ground-level ozone (O3), and risk of COVID-19-related hospital admission, intensive care unit (ICU) admission and death. We ascertained individuals’ long-term exposures to each air pollutant based on their residence from 2015 to 2019. We used logistic regression and adjusted for confounders and selection bias using various individual and contextual covariates obtained through data linkage.Results:Among the 151 105 people with confirmed SARS-CoV-2 infection in Ontario in 2020, we observed 8630 hospital admissions, 1912 ICU admissions and 2137 deaths related to COVID-19. For each interquartile range increase in exposure to PM2.5 (1.70 μg/m3), we estimated odds ratios of 1.06 (95% confidence interval [CI] 1.01–1.12), 1.09 (95% CI 0.98–1.21) and 1.00 (95% CI 0.90–1.11) for hospital admission, ICU admission and death, respectively. Estimates were smaller for NO2. We also estimated odds ratios of 1.15 (95% CI 1.06–1.23), 1.30 (95% CI 1.12–1.50) and 1.18 (95% CI 1.02–1.36) per interquartile range increase of 5.14 ppb in O3 for hospital admission, ICU admission and death, respectively.Interpretation:Chronic exposure to air pollution may contribute to severe outcomes after SARS-CoV-2 infection, particularly exposure to O3.By November 2021, COVID-19 had caused more than 5 million deaths globally1 and more than 29 400 in Canada.2 The clinical manifestations of SARS-CoV-2 infection range from being asymptomatic to multiple organ failure and death. Identifying risk factors for COVID-19 severity is important to better understand etiological mechanisms and identify populations to prioritize for screening, vaccination and medical treatment. Risk factors for severity of COVID-19 include male sex, older age, pre-existing medical conditions and being from racialized communities.3–5 More recently, ambient air pollution has been implicated as a potential driver of COVID-19 severity.6–10Long-term exposure to ambient air pollution, a major contributor to global disease burden,11 could increase the risk of severe COVID-19 outcomes by several mechanisms. Air pollutants can reduce individuals’ pulmonary immune responses and antimicrobial activities, boosting viral loads.8 Air pollution can also induce chronic inflammation and overexpression of the alveolar angiotensin-converting enzyme 2 (ACE) receptor,7 the key receptor that facilitates SARS-CoV-2 entry into cells.12,13 Exposure to air pollution contributes to chronic conditions, such as cardiovascular disease, that are associated with unfavourable COVID-19 prognosis, possibly owing to persistent immune activation and excessive amplification of cytokine development.10 Thus, greater exposure to long-term air pollution may lead to severe COVID-19 outcomes.Reports exist of positive associations between long-term exposure to particulate matter with diameters equal to or smaller than 2.5 or 10 μm (PM2.5 and PM10), ground-level ozone (O3) and nitrogen dioxide (NO2), and metrics of COVID-19 severity (e.g., mortality and case fatality rate).8–10 However, most studies to date have used ecological and cross-sectional designs, owing to limited access to individual data, which leads to ambiguity in interpreting the results, thus hindering their influence on policy. 6,14 Ecological designs do not allow for disentangling the relative impacts of air pollution on individual susceptibility to infection and disease severity.14 Residual confounding by factors such as population mobility and social interactions is also problematic. Therefore, a cohort study with data on individuals with SARS-CoV-2 is a more appropriate design.6,14 Studies that have used individual data were conducted in specific subpopulations15,16 or populations with few severe cases,17 or had limited data on individual exposure to air pollutants.18 In Canada, 1 ecological study found a positive association between long-term exposure to PM2.5 and COVID-19 incidence,19 but no published study has explored the association between air pollution and COVID-19 severity.We aimed to examine the associations between long-term exposure to 3 common air pollutants (PM2.5, NO2 and O3) and key indicators of COVID-19 severity, including hospital admission, intensive care unit (ICU) admission and death, using a large prospective cohort of people with confirmed SARS-CoV-2 infection in Ontario, Canada, in 2020. The air contaminants PM2.5, NO2 and O3 are regularly monitored by the Canadian government, and are key pollutants that are considered when setting air-quality policies. They originate from varying sources (NO2 is primarily emitted during combustion of fuel, O3 is primarily formed in air by chemical reactions of nitrogen oxides and volatile organic compounds, and PM2.5 can be emitted during combustion or formed by reactions of chemicals like sulphur dioxide and nitrogen oxides in air) and they may affect human health differently.20,21,22 相似文献
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利用大肠杆菌研究番茄红素的合成,不仅可以获得副产物少的高产菌株,而且可以探讨基因或基因簇的功能。文中将番茄LeGGPS2和LePSY1的cDNA序列,及欧文氏菌crtI的编码序列分别添加上核糖体结合位点后,以单独或组合的方式受控于T7启动子和终止子,在大肠杆菌菌株BL21(DE3)中进行表达和诱导番茄红素合成。结果显示,仅T7::crtI-LeGGPS2-LePSY1三价基因共表达时才能合成番茄红素,且将种子液以1∶50接种于含3%蔗糖的LB培养基(pH 6.8)中,于37℃摇8 h左右的对数生长后期加IPTG至80μmol/L,30℃诱导表达5 h的发酵条件下,获得2.124 mg/g DCW的番茄红素。该结果既验证了原核化的番茄LeGGPS2和LePSY1基因及与crtI基因协同作用的功能,又为在番茄质体中建立独立的番茄红素合成途径奠定了基础。 相似文献
50.
能源植物甜高粱种质资源和分子生物学研究进展 总被引:13,自引:0,他引:13
世界能源危机和全球生态环境日益恶化迫使人们急需开发可再生能源。生物质能源作为一种清洁的可再生能源已受到世界各国的高度重视。发展生物质能源的瓶颈之一是生物质原料不足。甜高粱的生物学产量和含糖量极高, 同时兼有耐旱、耐涝、耐贫瘠和耐盐碱等诸多优良特性, 被认为是最具开发潜力的能源植物之一。该文从甜高粱的分类学、生物学特点、种质资源评价、功能基因以及基因组信息等方面综述了甜高粱的最新研究进展和存在的问题, 并展望了甜高粱作为能源植物的研发前景。 相似文献