北美水貂和欧亚水獭在东北地区的分布与生态位重叠

作为入侵物种,北美水貂(Neovison vison)在欧洲引起了一系列生态问题,侵占了欧亚水獭(Lutra lutra)的生态空间,其入侵性对当地生物多样性和生态系统构成了严重威胁。水貂引入我国东北地区已有70多年的历史,然而国内对其野外种群却鲜有研究。掌握水貂种群的入侵范围、入侵影响因素以及与本地具有相似生态位的欧亚水獭之间的竞争关系,对水貂的入侵管理和东北地区的生物多样性保护具有重要意义。本研究利用实地调查和文献资料获取的分布信息,通过集合模型识别水貂和水獭的潜在分布区,评估水貂对水獭在地理空间上的入侵风险,并通过主成分分析(principal component analysis,PCA)评估其生态位重叠和影响因素。结果表明:(1)我国东北地区水貂的潜在分布区面积为61,944.57 km²,水獭的潜在分布区面积为83,590.94 km²,两者重叠区域面积为50,544.21 km²,占水獭潜在分布区面积的60.47%;(2)从各省分布情况来看,黑龙江省水獭受水貂入侵的风险最高,潜在分布区重叠的比例达到78.9...     

Inhibition of TREM-1 and Dectin-1 Alleviates the Severity of Fungal Keratitis by Modulating Innate Immune Responses

Purpose

To explore the possibility that inhibiting triggering receptor expressed on myeloid cells-1 (TREM-1) and Dendritic cell-associated C-type lectin-1(Dectin-1) could modulate the innate immune response and alleviate the severity of corneal fungal keratitis.

Method

TREM-1 and Dectin-1 expression was detected in fungus-infected human corneal specimens by real-time PCR. C57BL/6 (B6) mice were injected with Aspergillus fumigatus and divided into 4 groups that received subconjunctival injections of PBS and IgG as a control (group I), mTREM-1/IgG fusion protein (group II), the soluble β-glucan antagonist laminarin (group III), or mTREM-1/Fc and laminarin (group IV). Corneal virulence was evaluated based on clinical scores. TREM-1 and Dectin-1 mRNA levels were assayed using real-time PCR. The distribution patterns of TREM-1, Dectin-1 and cellular infiltrates in fungus-infected corneas were examined by immunohistochemistry. Moreover, changes in T Helper Type1 (Th1)-/ T Helper Type1 (Th2)- type cytokines and proinflammatory cytokines were measured.

Results

The expression of TREM-1 and Dectin-1 increased significantly and correlated positively with the progression of fungal keratitis. Most infiltrated cells were neutrophils and secondarily macrophages in infected cornea. The clinical scores decreased after interfering with TREM-1 and Dectin-1 expression in infected mouse corneas. Levels of Th1-type cytokines including interleukin-12 (IL-12), IL-18 and interferon-γ (IFN-γ) were decreased in the cornea, while the levels of Th2-type cytokines, including IL-4, IL-5 and IL-10, showed obvious increases.

Conclusion

TREM-1 and Dectin-1 function concurrently in the corneal innate immune response by regulating inflammatory cytokine expression in fungal keratitis. Inhibition of TREM-1 and Dectin-1 can alleviate the severity of corneal damage by downregulating the excessive inflammatory response.     

JAK-STAT signaling mediates the senescence of cartilage-derived stem/progenitor cells

Journal of Molecular Histology - Aging is a major risk factor for degenerative joint diseases, such as osteoarthritis (OA). Previous studies have confirmed the link between senescent mesenchymal...     

Investigation on the Tribological Behavior and Wear Mechanism of Five Different Veneering Porcelains

Objectives

The primary aim of this research was to investigate the wear behavior and wear mechanism of five different veneering porcelains.

Methods

Five kinds of veneering porcelains were selected in this research. The surface microhardness of all the samples was measured with a microhardness tester. Wear tests were performed on a ball-on-flat PLINT fretting wear machine, with lubrication of artificial saliva at 37°C. The friction coefficients were recorded by the testing system. The microstructure features, wear volume, and damage morphologies were recorded and analyzed with a confocal laser scanning microscope and a scanning electron microscope. The wear mechanism was then elucidated.

Results

The friction coefficients of the five veneering porcelains differ significantly. No significant correlation between hardness and wear volume was found for these veneering porcelains. Under lubrication of artificial saliva, the porcelain with higher leucite crystal content exhibited greater wear resistance. Additionally, leucite crystal size and distribution in glass matrix influenced wear behavior. The wear mechanisms for these porcelains were similar: abrasive wear dominates the early stage, whereas delamination was the main damage mode at the later stage. Furthermore, delamination was more prominent for porcelains with larger crystal sizes.

Significance

Wear compatibility between porcelain and natural teeth is important for dental restorative materials. Investigation on crystal content, size, and distribution in glass matrix can provide insight for the selection of dental porcelains in clinical settings.     

Rac1 Is a Possible Link Between Obesity and Oxidative Stress in Chinese Overweight Adolescents

Enhanced nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity in the monocytes occurred in metabolic syndrome, hypertension, diabetes and obese patients in adults. However, whether NADPH oxidase is involved in the oxidative stress of overweight adolescents without comorbidities is still unclear. This study aimed to identify whether and how NADPH oxidase plays a crucial role in overweight adolescents. The study was performed in 93 overweight adolescents and 31 normal weight controls. Moreover, 87 overweight adolescents were enrolled in weight‐loss program. Demographics characteristics, anthropometrics, composition and clinical characteristics were analyzed. Oxidative stress indexes including the levels of superoxide dismutase (SOD) and malondialdehyde (MDA) in plasma and the expression of NADPH oxidase in the monocytes were examined. Overweight adolescents showed a higher oxidative stress state, as indicated by decreased SOD activity and elevated MDA level (P < 0.01). Furthermore, increased NADPH oxidase activity in the monocytes was accompanied by Rac1 upregulation. A significant positive bivariate correlation was found between Rac1 expression and MDA (r = 0.289). There also was a significant positive bivariate correlation between Rac1 expression and obesity‐related indexes including BMI (r = 0.227) and percentage of trunk fat (r = 0.233). Data from weight‐loss program reinforced the results. Partial correlation analysis indicated that obesity‐induced oxidative stress and Rac1 expression is a consequence of aberrant glucose‐lipid metabolism in overweight adolescents. In conclusion, we provided novel data showing that NADPH oxidase in the monocytes was highly activated by enhancing Rac1 expression in Chinese overweight adolescents and Rac1 may act as a link between obesity and oxidative stress in overweight adolescents.     

东北地区水獭分布格局与保护优先区识别

水獭是水生生态系统重要的指示种和旗舰种, 由于强烈的人为干扰, 中国的水獭种群数量大幅下降, 部分区域已局部灭绝。然而目前国内对水獭的调查和研究非常有限, 本底不清的状况已经严重影响到水獭的野外保育工作。本文以东北地区的欧亚水獭指名亚种(Lutra lutra lutra)为研究对象, 基于2016-2020年的调查数据, 使用组合建模的方法评估了水獭的潜在分布区; 利用地理信息系统和系统保护规划软件分析了水獭的保护优先区并计算了各省级行政区内水獭潜在分布区和保护优先区面临的人类压力; 结合国家级自然保护区的空间布局分析了水獭的保护现状, 并以内蒙古森工集团、大兴安岭林业集团、伊春森工集团三大国有林区为例分析了重点国有林区在水獭保护中的作用。结果表明: (1)水獭潜在分布区和保护优先区面积分别为104,515.04 km²和45,448.99 km², 其中大兴安岭的水獭保护优先区集中连片, 并与小兴安岭的保护优先区相连, 栖息地之间没有明显地理隔离, 是维持东北地区水獭种群稳定的重中之重; (2)水獭面临的人类压力大小依次为: 辽宁 > 吉林 > 黑龙江 > 内蒙古; (3)研究区内110个国家级自然保护区中有63个包含水獭潜在分布区, 覆盖面积为12,168.93 km², 仅占水獭潜在分布区面积的11.64%, 其中32个国家级自然保护区包含水獭保护优先区, 占水獭保护优先区面积的10.88%; (4)三大国有林区涵盖了71.18%的水獭潜在分布区和79.26%的保护优先区(面积分别为74,390.89 km²和36,022.22 km²)。由此可见, 尽管水獭潜在分布区中国家级自然保护区占比较低, 但是在天然林全面禁伐的背景下, 重点国有林区可能在未来东北地区的生物多样性保护中发挥更大作用, 因此我们建议将重点国有林区中具有重要保护价值的区域逐步纳入以国家公园为主体的自然保护地体系中, 以实现生物多样性的系统性和完整性保护。最后, 本文结合研究结果和实地调研提出以下保护建议: (1)加强对河流污染物的管理; (2)控制渔民捕鱼强度; (3)开展全面的水獭专项调查并建立长期的监测体系; (4)加大对水獭的科研投入; (5)加强宣传力度, 提升公众保护意识。