防风体细胞胚发生和发育的组织学研究

采用石蜡切片和半薄切片法研究组织培养中防风体细胞胚发生和发育的形态和结构特征,以了解体细胞再生形成胚胎结构的细胞分化和形态发生特征。结果表明:(1)胚性细胞内含有丰富的淀粉体,随细胞分裂和分化逐渐减少;(2)体细胞胚的发生发育经历了类似合子胚的各阶段;(3)多细胞原胚形成的分裂方式以平周分裂为主,并由此表现出有序生长;(4)在体细胞胚迅速发育过程中,不同阶段的体细胞胚始终与周围细胞存在明显界限;(5)胚柄发育不明显;(6)畸形胚常见,其中连体胚是胚性细胞发生密度过高造成的,而次生胚则在原来胚的基础上又产生新的胚的发生中心。     

铜绿假单胞菌pfm基因对三型分泌系统效应蛋白的影响

[目的]检测铜绿假单胞菌基因pfm对三型分泌系统效应蛋白的影响.[方法]构建pfm基因互补菌株pfmC.提取野生株PAO1、敲除株Δpfm和互补株pfmC的RNA,利用Real-time PCR从转录水平检测效应蛋白ExoS、ExoT和ExoY转录水平的变化.以ExoS为代表,检测细胞内和分泌到细胞外效应蛋白的含量.收集铜绿假单胞菌PAO1、Δpfm和pfmC菌体内和分泌到细胞外的总蛋白,利用ExoS多克隆抗体进行Western杂交,特异检测ExoS的蛋白水平.[结果]与野生型相比,Δpfm中exoS、exoT和exoY转录水平明显降低,而pfmC中这3个蛋白的转录水平得到回补.Δpfm菌体内和分泌到细胞外的ExoS量均明显低于野生株PAO1,pfmC细胞内和细胞外分泌的ExoS蛋白量均得到恢复.[结论]铜绿假单胞菌基因pfm会影响三型分泌系统效应蛋白的水平.     

副溶血弧菌CHY5-M1M噬菌体的分离鉴定及生物学特性分析

副溶血弧菌引起的疾病给水产养殖行业带来巨大损失,而随着抗生素的禁用,人们开始探索治疗水产动物病菌的新型方法,如噬菌体治疗法。从青岛市城阳水产品批发市场采集了15份海产品养殖水及下水道污水样品,以副溶血弧菌作为宿主菌,采用点滴法分离纯化获得12株副溶血弧菌噬菌体,通过双层平板法研究副溶血弧菌噬菌体CHY5-M1M的最佳感染复数、一步生长曲线、温度和pH的稳定性以及对紫外线的敏感度等生物学特性。结果显示,CHY5-M1M噬菌体效价为8.65×10¹³CFU·mL^-1,且在100感染复数时效价最高;一步生长曲线的潜伏期为20 min,裂解时长100 min,140min后达到平稳期;噬菌体在温度为40℃时效价最高,高于60℃时活性开始下降;噬菌体pH适应范围为5～11;噬菌体浓度随紫外照射时间增加明显下降;噬菌体基因组共43 193 bp,包含44个基因,无毒力因子基因和抗生素耐药基因。研究结果表明,噬菌体CHY5-M1M在开发新型抗弧菌药物、预防治疗严重海水动物弧菌病等方面具有良好的应用前景,有望作为未来的抗生素替代产品。     

北京市生态用地规划与管理对策

不合理土地开发加速了对自然生态系统的干扰和侵占,导致生态系统服务功能下降,危机区域生态安全,开展生态用地规划是构建区域生态安全格局的基础。合理规划和管理不同土地利用类型的数量和空间分布对区域可持续发展具有重要意义。目前我国广泛应用的土地利用分类体系主要以土地的社会经济属性为基础,忽视其生态属性,导致以提供生态系统服务为主、保障生态安全的土地缺乏保护机制,具有重要生态功能的土地得不到有效保护。以北京市为例,建立了北京市生态用地分类与规划的思路与程序,在明确北京市生态安全与生态系统服务功能的关系基础上分析了北京市生态系统服务功能重要性及其空间格局,并进行了北京市生态用地规划。研究规划了保障北京市生态安全的7类生态用地:地表水涵养与保护用地、地下水保护用地、生物多样性保护用地、水土保持用地、河流防护用地、公路防护用地和城市绿地,总面积5137.37km2,占北京市域面积的31.31%。最后从生态用地识别和划分、将生态用地融入土地利用分类体系、生态用地管理措施和对策3个方面探讨了生态用地规划和管理的方法与措施。研究结果为北京市土地利用规划和有效管理提供依据,也为其它地区的生态用地规划提供参考。     

长白山西坡小叶章侵入苔原带过程及影响

长白山西坡岳桦林带的草本植物(以小叶章为代表)侵入了苔原带,形成了独特的植物入侵现象。在光谱及影像分析的基础上,结合GPS(Global Positional System)定位技术,并依据小叶章与牛皮杜鹃的光谱差异及其反演的NDVI(Normalized Difference Vegetation Index)植被指数,揭示小叶章侵入苔原带的过程;通过对不同侵入时间、强度的斑块进行群落调查及土壤测试,探究小叶章侵入苔原带的生态后果。结果显示小叶章侵入苔原带始于20世纪80年代后期,由低海拔向高海拔推进,进入21世纪后逐渐形成了稳定的以小叶章为优势物种的植物群落结构。目前,低海拔处的小叶章斑块经过多年扩张已连接成片,而高海拔处的斑块正处于扩张的初期阶段。从生物多样性变化可以看出,小叶章侵入苔原带导致植物群落多样性升高和物种数量的增加,苔原带原有的灌木数量明显减少,草本植物逐渐增多。植被的改变影响了土壤的理化性质,C/N比下降,土壤腐殖质含量和全氮含量下降,但速效氮和土壤持水能力上升,土壤养分的高效利用又进一步推动了小叶章的侵入。小叶章侵入苔原带已经造成了严重的生态后果。     

生态环境损害鉴定评估业务化技术研究

随着社会经济的不断发展和人类需求的不断提高,我国生态环境损害事件屡有发生,由于人类活动导致的典型生态系统结构和功能退化、生态系统服务降低等生态环境损害严重威胁到我国的生态安全。系统研究典型生态系统生态环境损害基线、因果关系及损害程度的判定技术方法对保障国家生态安全和实现可持续发展具有重要的理论和实践意义。根据国家"十三五"《典型脆弱生态修复与保护研究专项指南》的要求,中国科学院大学牵头组织6家课题牵头单位联合申报了"生态环境损害鉴定评估业务化技术研究"项目,通过了专业机构组织的评审,获准立项。本文对该项目的研究背景、总体目标、主要内容及预期产出进行了介绍。该项目的开展将对典型生态环境损害评估提供决策支持,为国家在政策层面解决环境损害追责、环境执法与管理提供科学技术和平台支撑。     

Association between long-term exposure to ambient air pollution and COVID-19 severity: a prospective cohort study

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 (PM_2.5), 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 PM_2.5 (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 (PM_2.5 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 subpopulations^15,16 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 PM_2.5 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 (PM_2.5, 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 PM_2.5, 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 PM_2.5 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     

拉恩氏菌W25对缓冲容量的响应及其产酸特性

【目的】进一步了解拉恩氏菌W25的溶磷机理和对土壤缓冲容量的响应。【方法】在液体摇瓶培养过程中,采用调节培养液pH的方法研究模拟土壤的缓冲容量对拉恩氏菌W25溶磷量的影响;通过单因子试验和HPLC相结合的方法,研究不同碳源、磷源条件下W25的溶磷能力及产酸特性。【结果】拉恩氏菌W25在磷酸三钙培养液中培养120 h后有效磷含量达到最大值,培养液有效磷含量与培养液pH变化之间呈极显著负相关性(P<0.01);W25在培养第48?96 h具有较强的缓冲能力,培养液有效磷含量加碱处理与未加碱处理差异不显著(P<0.05),从第120 h开始,缓冲能力开始减弱,在168 h后基本丧失了缓冲能力;W25在不同碳源条件下溶磷能力差异显著(P<0.05),依次为葡萄糖>乳糖>蔗糖>甘露醇>淀粉,不同磷源中培养液有效磷含量差异极显著(P<0.01),依次为磷酸三钙>磷酸铁>磷酸铝>磷矿粉;不同碳源、磷源条件下W25培养液中有机酸的种类和浓度差异较大,W25溶磷能力的大小不仅与产酸的种类有关,而且也与产酸的浓度有关。【结论】研究结果为更深入研究拉恩氏菌溶磷机理提供条件,为拉恩氏菌的应用提供理论基础。     

抗生素和高脂饮食对大鼠肠道乳杆菌多样性的影响

【目的】对正常、高脂、抗生素处理大鼠肠道内乳杆菌进行定性和定量分析,比较不同处理组大鼠肠道乳杆菌的多样性。【方法】应用纯培养和非培养技术(16S r RNA基因序列分析、变性梯度凝胶电泳、实时荧光定量PCR)对大鼠肠道乳杆菌进行分离鉴定和多样性分析。【结果】16S r RNA基因序列同源性分析结果显示,正常组大鼠肠道内分离出的乳杆菌包括约氏乳杆菌(Lactobacillus johnsonii)、鼠乳杆菌(Lactobacillus murinus)、嗜酸乳杆菌(Lactobacillus acidophilus)、罗伊氏乳杆菌(Lactobacillus reuteri)、植物乳杆菌(Lactobacillus plantarum)、肠道乳杆菌(Lactobacillus intestinals)、动物乳杆菌(Lactobacillus animalis)和阴道乳杆菌(Lactobacillus vaginalis);但L.animalis在高脂处理组大鼠肠道内未分离到,L.intestinals和L.vaginalis在抗生素处理组大鼠中未分离到。DGGE结果显示3个组别大鼠肠道中乳杆菌构成差异明显,同一组内样品间相似性较高;相较于正常组和高脂组,抗生素组的丰度较差;且正常组大鼠肠道内乳杆菌的多样性高于高脂组和抗生素组。q-PCR结果显示正常组大鼠肠道乳杆菌的数量明显高于高脂组和抗生素组,高脂组的数量也明显高于抗生素组,且3个组别之间存在显著差异(P0.01)。【结论】高脂饮食及抗生素的使用会减少肠道内乳杆菌多样性。     

哈尔滨城市和乡村青年居民肠道菌群多样性研究

【目的】分析居住于哈尔滨城市和乡村的青年居民肠道菌群多样性的异同。【方法】采用PCR和DGGE技术相结合的方法对生活于哈尔滨城市和乡村的青年志愿者肠道菌群多样性进行研究。基于DGGE指纹图谱,分别使用聚类和PCA分析对志愿者肠道微生物相似性进行分析,使用Shannon-Weine多样性指数(H′)、丰度(S)和均匀度(EH)对志愿者肠道微生物多样性进行分析,对图谱中具有代表性的共性和特异性条带进行胶回收和克隆测序以分析志愿者肠道微生物组成。基于PCR技术在种水平上对城乡志愿者肠道内乳杆菌属和双歧杆菌属多样性进行定性分析。【结果】相似性分析显示,城乡青年居民间肠道微生物群落结构存在分开趋势,相似性小于城市或乡村青年居民内部;多样性分析显示,城乡青年居民肠道微生物多样性差异不显著;测序结果表明,城乡居民肠道微生物组成在门水平上相同,但是在种属水平上存在差异。PCR定性分析显示Lactobacillus plantarum、L.casei和L.salivarius在哈尔滨城乡青年居民肠道内检出率接近100%,Bifidobacterium longum和B.breve的检测率约90%,在哈尔滨城乡青年居民肠道内普遍存在;乳杆菌属和双歧杆菌属各细菌种在城乡居民肠道中的检出频率差异不显著。【结论】哈尔滨城市和乡村青年居民肠道微生物多样性差异不显著。