基于NDVI的三江源地区植被生长对气候变化和人类活动的响应研究

采用Spot VEGETATION 逐旬NDVI数据、1 ∶ 100万植被类型图和气象站资料,在掌握近10a三江源地区植被变化趋势基础上,分不同植被类型探讨植被生长对气候变化的响应机制,并通过分离气候要素与人类活动对NDVI的贡献,定量评估生态保护与建设工程的实施效果。结果表明,区域尺度上,三江源地区2001-2010年植被生长呈好转趋势,植被增长从东南向西北递减;在10a时间尺度上,气候变化是影响植被生长的决定性因素,但人类活动可在短期内加快植被变化速率,气候要素和人类活动对植被生长的贡献分别为79.32%和20.68%;降水和气温对植被生长的影响程度相当,其中受春季和秋季的降水和气温影响最大,尤其是植被生长季前后一个月(4月份和10月份)的气候条件;与林地和灌丛相比,高寒草地受气候条件的抑制作用更为明显,其中高寒草甸受气候变化的影响最大,NDVI与降水和气温均具有较高相关性,高寒草原受气温的影响比较大,而高山植被受降水的抑制作用更为明显;在气候条件利于植被生长的趋势下,2001-2010年三江源地区的人类活动对生态环境表现出正影响,实测NDVI_max与模拟NDVI_max之间的残差为0.0863,表明生态保护与建设行动取得初步成效,其中黄河源区东部和长江源区通天河两侧的生态恢复效益最为明显,而在唐古拉山、昆仑山、布青山、阿尼玛卿山等山脉的周边地区,人类活动对生态环境仍表现为负影响;时间尺度上人类活动对植被的正影响呈现出下降趋势,2001-2010年NDVI_max残差的回归斜率为-0.0039,表明生态项目实施的短期行为严重,生态建设的效果缺乏长效性。     

Structure-based design and structure-activity relationships of 1,2,3,4-tetrahydroisoquinoline derivatives as potential PDE4 inhibitors

This paper describes our medicinal chemistry efforts on 7-(cyclopentyloxy)-6-methoxy1,2,3,4-tetrahydroisoquinoline scaffold: design, synthesis and biological evaluation using conformational restriction approach and bioisosteric replacement strategy. Biological data revealed that the majority of the synthesized compounds of this series displayed moderate to potent inhibitory activity against PDE4B and strong inhibition of LPS-induced TNFα release. Among them, compound 19 exhibited the strongest inhibition against PDE4B with an IC₅₀ of 0.88?µM and 21 times more potent selectivity toward PDE4B over PDE4D when compared to rolipram. A primary structure-activity relationship study showed that the attachment of CH₃O group or CF₃O group to the phenyl ring at the para-position was helpful to enhance the inhibitory activity against PDE4B. Moreover, sulfonamide group played a key role in improving the inhibitory activity against PDE4B and subtype selectivity. In addition, the attachment of the additional rigid substituents at the C-3 position of 1,2,3,4-tetrahydroisoquinoline ring was favored to subtype selectivity, which was consistent well with the observed docking simulation.     

黄土高原水土流失治理现状、问题及对策

黄土高原位于黄河中游地区,是世界上水土流失最为严重的区域之一;黄土高原水土流失治理问题历来受到国家高度关注,涌现了种类多样的水土流失治理模式,目前还缺乏对黄土高原区域尺度水土流失治理模式的总结和整理。本文总结和整理了建国以来黄土高原主要的四类水土流失治理模式,生物措施模式主要由退耕还林、荒山造林和封山育林工程组成,工程措施模式包括修建梯田和淤地坝,以及近期涌现的治沟造地工程;小流域综合治理模式主要体现在坡面、沟道系统整治,生物和工程措施相结合的特点,区域综合整理模式则强调对生态系统进行整体保护、系统修复和综合治理,达到生态、社会、经济可持续发展。基于黄土高原水土流失治理模式存在的问题,提出了黄土高原水土流失治理模式调整和优化建议,以期对黄土高原生态恢复建设和水土流失科学治理提供科学依据。     

Effects of 5-aminolevulinic acid on the inflammatory responses and antioxidative capacity in broiler chickens challenged with lipopolysaccharide

5-Aminolevulinic acid (5-ALA) is an intermediate in haem biosynthesis and has anti-apoptotic, anti-inflammatory, antioxidant, and other pharmacological effects. This study aimed to investigate the effect of dietary supplementation with 5-ALA on growth performance, antioxidant capacity, and inflammatory response of the lipopolysaccharide (LPS)-challenged broiler chickens. The experiment was designed as a 2 × 2 factorial arrangement with dietary 5-ALA (0 or 60 mg/kg) and LPS (injection of saline or 0.5 mg/kg BW) levels as treatments. A total of 240 one-day-old Arbor Acres broilers were distributed into four treatments consisting of six replicates of 10 birds. All the experimental broilers were intraperitoneally injected with LPS or sterile saline at 16, 18, and 20 days of age. Our results showed that dietary 5-ALA supplementation reduced (P < 0.05) the feed to gain before broilers were stimulated with LPS (days 1–15). LPS challenge decreased (P < 0.05) the catalase (CAT), total superoxide dismutase activities and increased the content of malondialdehyde (MDA) in the serum of broiler chickens. However, 5-ALA supplementation had a tendency to increase (P = 0.08) the activity of CAT and decreased (P < 0.05) the content of MDA. LPS challenge showed higher (P < 0.05) interleukin (IL)-1β, IL-6, and IL-10 concentrations in the serum, whereas dietary 5-ALA supplementation decreased (P < 0.05) the levels of IL-1β and IL-6. Additionally, dietary 5-ALA supplementation significantly attenuated (P < 0.05) the upregulation of mRNA expression levels of hepatic toll-like receptor 4 (TLR4), IL-1β, and IL-2 induced by LPS challenge. Moreover, dietary 5-ALA supplementation also enhanced the mRNA expression of 5-aminolevulinate dehydratase, ferrochelatase, and haem oxygenase-1 (HO-1) as compared to the unsupplemented groups. In conclusion, our results suggested that supplementation of 60 mg/kg 5-ALA exhibited LPS-induced anti-inflammatory and antioxidant properties by enhancing the HO-1 expression and inhibiting the TLR4/NF-κB signalling pathway.     

The Effects of Mobile Phone Radiofrequency Radiation on Cochlear Stria Marginal Cells in Sprague–Dawley Rats

To investigate the possible mechanisms for biological effects of 1,800 MHz mobile radiofrequency radiation (RFR), the radiation-specific absorption rate was applied at 2 and 4 W/kg, and the exposure mode was 5 min on and 10 min off (conversation mode). Exposure time was 24 h short-term exposure. Following exposure, to detect cell DNA damage, cell apoptosis, and reactive oxygen species (ROS) generation, the Comet assay test, flow cytometry, DAPI (4′,6-diamidino-2-phenylindole dihydrochloride) staining, and a fluorescent probe were used, respectively. Our experiments revealed that mobile phone RFR did not cause DNA damage in marginal cells, and the rate of cell apoptosis did not increase (P > 0.05). However, the production of ROS in the 4 W/kg exposure group was greater than that in the control group (P < 0.05). In conclusion, these results suggest that mobile phone energy was insufficient to cause cell DNA damage and cell apoptosis following short-term exposure, but the cumulative effect of mobile phone radiation still requires further confirmation. Activation of the ROS system plays a significant role in the biological effects of RFR. Bioelectromagnetics. © 2020 The Authors. Bioelectromagnetics published by Wiley Periodicals, Inc.     

转基因烟草生产霍乱毒素B亚单位的纯化

提取转基因烟草叶片总蛋白,用经溴化氰活化的Ｓｅｐｈａｒｏｓｅ ４Ｂ偶联有抗ＣＴ ＩｇＧ色谱柱,得到了表达产物ＣＴＢ蛋白质。经ＰＡＧＥ、Ｗｅｓｔｅｒｎ ｂｌｏｔ、琼脂糖免疫扩散和免疫电泳等方法鉴定表明该蛋白与天然ＣＴＢ相同。     

MiR-674-5p Suppresses the Proliferation and Migration of Glioma Cells by Targeting Cul4b

Neurochemical Research - Glioma multiforme (GBM) is the most common malignant primary brain tumors. Despite the considerable advances in GBM treatment, it is still one of the most lethal forms of...