冻融条件下生物结皮覆盖对土壤饱和导水率的影响

生物结皮(BSC)是广泛分布的地被物,每逢冬春季节,受冻融交替作用影响,结皮土壤的理化性质和水文学特征明显改变且与裸土差异显著,从而影响该地区土壤可蚀性评估和土壤侵蚀防治。采用室内模拟实验,以蓝藻结皮土壤为对象,研究不同冻融交替次数和初始含水量下,土壤三相对温度变化的响应特征并定量分析结皮覆盖土壤在此条件下饱和导水率(Ks)的变化趋势和突变点。结果表明:初始含水量对Ks无显著影响(P>0.05),冻融交替次数对Ks有极显著影响(P<0.01),冻融条件下裸土的平均Ks为1.941 mm/min,结皮覆盖土壤平均Ks为0.325 mm/min,两者具有极显著差异(P<0.01),且随交替次数增加,Ks差异逐渐增大,并在10次时达到最大值为10.13倍。不同冻融含水量下的结皮土壤的Ks在冻融10—20次时趋近,平均值为0.219mm/min。冻融作用显著改变土壤结构,且在冻融7次时土壤结构变化较明显,冻融过程中<0.1 mm的土壤颗粒显著变化。试验条件下,Ks受因子影响程度大小为:冻融交替次数>土壤结构>结皮厚度>结皮容重>下层土壤容重>...     

Liquid–liquid phase separation of amyloid-β oligomers modulates amyloid fibrils formation

Soluble amyloid-β oligomers (AβOs) are proposed to instigate and mediate the pathology of Alzheimer’s disease, but the mechanisms involved are not clear. In this study, we reported that AβOs can undergo liquid–liquid phase separation (LLPS) to form liquid-like droplets in vitro. We determined that AβOs exhibited an α-helix conformation in a membrane-mimicking environment of SDS. Importantly, SDS is capable of reconfiguring the assembly of different AβOs to induce their LLPS. Moreover, we found that the droplet formation of AβOs was promoted by strong hydrated anions and weak hydrated cations, suggesting that hydrophobic interactions play a key role in mediating phase separation of AβOs. Finally, we observed that LLPS of AβOs can further promote Aβ to form amyloid fibrils, which can be modulated by (−)-epigallocatechin gallate. Our study highlights amyloid oligomers as an important entity involved in protein liquid-to-solid phase transition and reveals the regulatory role of LLPS underlying amyloid protein aggregation, which may be relevant to the pathological process of Alzheimer’s disease.     

暴露生态学视角下绿地暴露健康效益研究进展

城市绿地与居民健康福祉密切相关,绿地暴露所带来的多重健康效益已经成为耦合城市生态与健康科学的前沿热点议题。尽管绿地健康效应的综述研究并不鲜见,但是目前仍缺乏基于统一理论框架视角下对绿地暴露健康效益的系统综述。近期提出的暴露生态学作为一个耦合"自然生态系统-生态暴露-健康效应"框架体系,能够全面剖析、归纳已有绿地暴露健康效应研究,并指引未来相关领域研究发展。因此,研究在暴露生态学研究视域下,在主体-现实,客体-现实,主体-虚拟,客体-虚拟界面下进行了研究进展的综述分析,并指出了研究截面(尺度)单一、阈值研究与虚拟(及多感官)研究不足等问题。最后提出了未来研究展望:(1)构建跨时空、多尺度的绿地暴露测度模型,并量化绿地健康之间的因果效应;(2)构建阈值模型,分析健康促进的绿地暴露主体阈值与客体阈值;(3)探索绿地特征、暴露方式和剂量、多感体验对健康的影响。研究成果可以进一步加深对相关领域前沿与不足的认识,也可以进一步促进暴露生态学理论体系的丰富和完善。     

抑瘤基因NGX6对鼻咽癌细胞株HNE1细胞生长的影响(英文)

鼻咽癌是我国南方多发恶性肿瘤 ,它的发生发展与遗传因素密切相关 .采用定位候选克隆策略在 9p上克隆出一个候选抑瘤基因 ,命名为NGX6 .为了进一步研究它的功能 ,将NGX6基因的全长cDNA片段亚克隆至pcDNA3.1(+ )的表达载体中 ,通过脂质体转染入鼻咽癌细胞系HNE1中 ,Northern杂交方法筛选高效表达NGX6的细胞株 ,并借助细胞生长曲线、软琼脂糖集落形成实验、裸鼠体内接种实验和流式细胞仪对转染细胞的生物学行为进行了检测 .结果显示 ,转染了NGX6基因的HNE1细胞的生长速度明显减慢 ,在软琼脂中集落形成率较对照组显著下降 (P〈0 0 5 ) ,裸鼠体内成瘤的时间较对照组明显延长 ,瘤体的大小和重量较对照组明显减少 ,流式细胞仪检测发现细胞的凋亡率无明显变化 .为了明确NGX6蛋白在细胞中发挥作用的部位 ,进一步将NGX6的开放阅读框架完整正确地克隆到pEGFPC1的荧光载体中 ,转染到COS7细胞中 ,用荧光显微镜观察细胞中荧光的分布 ,发现荧光主要分布在细胞浆中 ,说明NGX6蛋白可能是一种胞浆蛋白 .该研究表明 ,NGX6在NPC的发生发展中起重要作用 ,为全面阐述NGX6的功能提供重要的信息 ,为进一步的功能研究打下基础     

Taxonomy on crane flies in family Tipulidae and Limoniidae (Diptera: Tipuloidea) from Yaoluoping National Nature Reserve,Anhui, China

The paper reports 13 species from Yaoluoping National Nature Reserve,Anhui,China,including a new species and a new subspecies,Tipula (Emodotipula) alexanderi Men,sp.nov.and Nephrotoma impigra anqingensis Men,subsp.nov.The female of Libnotes (Libnotes) pseudonohirai Men,2015 is described and illustrated for the first time.The males of Holorusia henana Yang,1999 and Tipula (Vestiplex)jiangi Yang & Yang,1991 are redescribed and illustrated with new morphological characters.A key to all species is provided.     

体内精原干细胞转染法建立转基因小鼠

将人Bcl-2 cDNA与小鼠乳清酸蛋白(WAP)5’上游调控序列融合后,与脂质体按一定比例混合,再加入适量的台盼蓝制成转染液,注入到小鼠睾丸中的曲细精管中,转染精原干细胞以探讨建立转基因小鼠的可行性。共注射了3只公鼠,4天后将公鼠与发情母鼠合笼交配,共生仔鼠20只。检测结果表明,有3只呈PCR阳性,Southern blot检测,阳性鼠2只,1只公鼠,1只母鼠,其中,公鼠意外死亡;Western blot证实,1只母鼠的乳腺组织表达了Bcl-2蛋白,其F1代的16只小鼠中,有7只呈PCR阳性。证实了体内精原干细胞转染建立转基因动物的可行性。     

Liver X receptor activation induces podocyte injury via inhibiting autophagic activity

Podocyte injury plays a key role in the occurrence and development of kidney diseases. Decreased autophagic activity in podocyte is closely related to its injury and the occurrence of proteinuria. Liver X receptors (LXRs), as metabolic nuclear receptors, participate in multiple pathophysiological processes and express in several tissues, including podocytes. Although the functional roles of LXRs in the liver, adipose tissue and intestine are well established; however, the effect of LXRs on podocytes function remains unclear. In this study, we used mouse podocytes cell line to investigate the effects of LXR activation on podocytes autophagy level and related signaling pathway by performing Western blotting, RT-PCR, GFP-mRFP-LC3 transfection, and immunofluorescence staining. Then, we tested this effect in STZ-induced diabetic mice. Transmission electron microscopy and immunohistochemistry were employed to explore the effects of LXR activation on podocytes function and autophagic activity. We found that LXR activation could inhibit autophagic flux through blocking the formation of autophagosome in podocytes in vitro which was possibly achieved by affecting AMPK, mTOR, and SIRT1 signaling pathways. Furthermore, LXR activation in vivo induced autophagy suppression in glomeruli, leading to aggravated podocyte injury. In summary, our findings indicated that activation of LXRs induced autophagy suppression, which in turn contributed to the podocyte injury.

     

利用定点突变分析白念珠菌依赖铁基因FRP1启动子元件

通过对白念珠菌高铁还原酶基因FRP1启动子进行突变分析, 确认启动子中特殊调控元件。我们通过分析FRP1起始密码子上游1000 bp序列发现在-160 和-650处有2个推测的Rim101p结合位点, 对其分别进行定点突变, 然后构建启动子与报告基因LacZ融合质粒, 转化整合到白念珠菌rim101-/-株和野生株中, 检测不同缺铁条件下b-半乳糖苷酶活性。结果发现碱性条件, Rim101p能够正向调控FRP1的表达; 启动子-160处突变对启动子功能影响较弱, 而-650突变使启动子活性大大降低, 此结果和双突变的结果相同, 表明Rim101p主要通过与启动子-650处结合位点相互作用来调控FRP1的表达。