铁代谢与铁调素hepcidin

铁是机体必需的营养元素。然而,铁过载则导致细胞的损伤。由于生物体缺少排泄铁的机制,因而,肠铁吸收的调控便成为维持机体铁稳态的关键。新近研究发现hepcidin对机体铁稳态的调节起着至关重要的作用,被人们称为铁调节激素。Hepcidin主要在肝细胞中合成,之后分泌至血液将体内铁需要的信号传至小肠,调控肠铁的吸收。这一过程主要通过调节小肠铁转运相关蛋白的表达而实现。任何影响hepcidin表达的因素都可能破坏体内的铁平衡,造成铁代谢相关疾病。     

我国单季稻种植区的气候适宜性

从国家层次和年尺度阐明影响我国单季稻种植区分布的主导气候因子, 揭示我国单季稻种植区的潜在分布及其气候适宜性,可为我国优化单季稻生产布局、改进种植制度和引种提供科学依据.本文从国家层次和年尺度选取影响我国单季稻分布的潜在气候因子, 利用其地理分布信息,结合最大熵模型和ArcGIS的空间分析功能, 阐明影响我国单季稻分布的主导气候因子并构建我国单季稻分布与气候的关系模型. 结果表明: 影响我国单季稻潜在种植区分布的主导气候因子是年降水量、湿润指数和稳定通过18 ℃日数, 它们对单季稻分布的累积贡献率达到了潜在气候因子的94.5%; 基于主导气候因子和单季稻种植点分布的地理信息, 结合最大熵模型构建的我国单季稻种植区分布与气候的关系模型能够很好地模拟我国单季稻种植区的潜在分布. 根据待预测区单季稻的存在概率, 明确了我国单季稻种植区潜在分布的气候低、中、高适宜区和气候不适宜区, 并分析了各气候适宜区的气候特征.     

传染性法氏囊病毒的抗原及分子特征

用鸡胚成纤维细胞对来自野外的 5 个传染性法氏囊病毒株 (IBDV-JD1 、 JD2 、 NB 、 HZ1 、 HZ2) 进行分离,测定理化特性、致病性,同时进行血清亚型测定及 A 片段基因组的克隆分析 . 试验所用 5 个法氏囊组织悬液在鸡胚成纤维细胞盲传 2~14 代后适应细胞并产生细胞病变 . 细胞适应的 IBDV 毒株的理化和形态特征与经典传染性法氏囊病毒株一致 . 除 IBDV-HZ1 、 HZ2 属经典 IBDV 血清型外, IBDV-JD1 、 JD2 和 NB 毒株分属不同的血清亚型 . 人工感染实验结果显示,分离的 IBDV 毒株产生与野外病例相似的临床症状和病变,出现法氏囊滤泡髓质的淋巴细胞变性、坏死和消失 . 基因组序列分析显示, IBDV-NB 毒株 A 片段由 3 264 个核苷酸组成,编码由 145 个氨基酸残基组成的 VP5 和由 1 012 个氨基酸残基组成的多聚蛋白 . 与来自 GenBank 的 IBDV Ⅰ型毒株比较, NB 毒株 A 片段编码的多聚蛋白与 JD1 毒株的同源性最高,达 99.5% , VP2 与 JD1 、 CEF94 、 D78 的同源性为 99.8% , VP3 与 JD1 的同源性为 99.2% , VP4 与 JD1 的同源性为 100% , VP5 与 JD1 , HZ2 , P2 , CEF94 , CT , Cu-1 和 D78 毒株的同源性为 99.3%. NB 毒株 VP2 蛋白的第 253 、 280 、 284 位氨基酸残基与 IBDV 变异毒株和经典毒株一致,但不同于 IBDV 超强毒株 . 这些结果暗示 IBDV 的抗原表位是构象依赖性表位, IBDV 血清亚型的形成与 IBDV 弱毒疫苗病毒株密切相关 .     

模拟氮沉降对温带典型森林土壤有效氮形态和含量的影响*

通过室内模拟氮沉降试验,研究了氮沉降对温带典型森林土壤有效氮的影响.结果表明:试验期间,与对照相比,经过氮沉降处理的土壤铵态氮、硝态氮和有效氮均呈增长的趋势,增加的程度取决于森林类型、土层、氮处理类型和氮处理的持续时间.氮沉降对不同林型土壤有效氮形态和含量的影响不同,氮沉降对混交林的影响弱于阔叶林,强于针叶人工纯林;土壤A层对氮沉降的敏感程度大于土壤B层;铵态氮形态沉降对土壤铵态氮含量的影响比对土壤硝态氮含量的影响大,而硝态氮形态沉降对土壤硝态氮含量的影响比对土壤铵态氮含量的影响大,混合形态的氮沉降对二者均有促进作用,且增加幅度更高;氮沉降对土壤有效氮的影响存在累加效应.     

Macrophage Depletion Impairs Corneal Wound Healing after Autologous Transplantation in Mice

Purpose

Macrophages have been shown to play a critical role in the wound healing process. In the present study, the role of macrophages in wound healing after autologous corneal transplantation was investigated by depleting local infiltrated macrophages.

Methods

Autologous corneal transplantation model was used to induce wound repair in Balb/c mice. Macrophages were depleted by sub-conjunctival injections of clodronate-containing liposomes (Cl₂MDP-LIP). The presence of CD11b⁺ F4/80⁺ macrophages, α-smooth muscle actin⁺ (α-SMA⁺) myofibroblasts, CD31⁺ vascular endothelial cells and NG₂ ⁺ pericytes was examined by immunohistochemical and corneal whole-mount staining 14 days after penetrating keratoplasty. Peritoneal macrophages were isolated from Balb/c mice and transfused into conjunctiva to examine the recovery role of macrophages depletion on wound healing after autologous corneal transplantation.

Results

Sub-conjunctival Cl₂MDP-LIP injection significantly depleted the corneal resident phagocytes and infiltrated macrophages into corneal stroma. Compared with the mice injected with PBS-liposome, the Cl₂MDP-LIP-injected mice showed few inflammatory cells, irregularly distributed extracellular matrix, ingrowth of corneal epithelium into stroma, and even the detachment of donor cornea from recipient. Moreover, the number of macrophages, myofibroblasts, endothelial cells and pericytes was also decreased in the junction area between the donor and recipient cornea in macrophage-depleted mice. Peritoneal macrophages transfusion recovered the defect of corneal wound healing caused by macrophages depletion.

Conclusions

Macrophage depletion significantly impairs wound healing after autologous corneal transplantation through at least partially impacting on angiogenesis and wound closure.     

Discovering Candidate Chromosomal Regions Linked to Kernel Size-Related Traits via QTL Mapping and Bulked Sample Analysis in Maize

Kernel size-related traits, including kernel length, kernel width, and kernel thickness, are critical components in determining yield and kernel quality in maize (Zea mays L.). Dissecting the phenotypic characteristics of these traits, and discovering the candidate chromosomal regions for these traits, are of potential importance for maize yield and quality improvement. In this study, a total of 139 F2:3 family lines derived from EHel and B73, a distinct line with extremely low ear height (EHel), was used for phenotyping and QTL mapping of three kernel size-related traits, including 10-kernel length (KL), 10-kernel width (KWid), and 10-kernel thickness (KT). The results showed that only one QTL for KWid, i.e., qKWid9 on Chr9, with a phenotypic variation explained (PVE) of 13.4% was detected between SNPs of AX-86298371 and AX-86298372, while no QTLs were detected for KL and KT across all 10 chromosomes. Four bulked groups of family lines, i.e., Groups I to IV, were constructed with F2:3 family lines according to the phenotypic comparisons of KWid between EHel and B73. Among these four groups, Group I possessed a significantly lower KWid than EHel (P = 0.0455), Group II was similar to EHel (P = 0.34), while both Group III and Group IV were statistically higher than EHel (P < 0.05). Besides, except Group IV exhibited a similar KWid to B73 (P = 0.11), KWid of Groups I to III were statistically lower than B73 (P < 0.00). By comparing the bulked genotypes of the four groups to EHel and B73, a stable chromosomal region on Chr9 between SNPs of AX-86298372 to AX-86263154, entirely covered by qKWid9, was identified to link KWid with the positive allele of increasing phenotypic effect to KWid from B73, similar to that of qKWid9. A large amount of enzyme activity and macromolecule binding-related genes were annotated within this chromosomal region, suggesting qKWid9 as a potential QTL for KWid in maize.     

Treatment of H2S using a horizontal biotrickling filter based on biological activated carbon: reactor setup and performance evaluation

Biological treatment is an emerging and prevalent technology for treating off-gases from wastewater treatment plants. The most commonly reported odorous compound in off-gases is hydrogen sulfide (H₂S), which has a very low odor threshold. A self-designed, bench-scale, cross-flow horizontal biotrickling filter (HBF) operated with bacteria immobilized activated carbon (termed biological activated carbon—BAC), was applied for the treatment of H₂S. A mixed culture of sulfide-oxidizing bacteria dominated by Acidithiobacillus thiooxidans acclimated from activated sludge was used as bacterial seed and the biofilm was developed by culturing the bacteria in the presence of carbon pellets in mineral medium. HBF performance was evaluated systematically over 120 days, depending on a series of changing factors including inlet H₂S concentration, gas retention time (GRT), pH of recirculation solution, upset and recovery, sulfate accumulation, pressure drop, gas-liquid ratio, and shock loading. The biotrickling filter system can operate at high efficiency from the first day of operation. At a volumetric loading of 900 m³ m^–3 h^–1 (at 92 ppmv H₂S inlet concentration), the BAC exhibited maximum elimination capacity (113 g H₂S/m^–3 h^–1) and a removal efficiency of 96% was observed. If the inlet concentration was kept at around 20 ppmv, high H₂S removal (over 98%) was achieved at a GRT of 4 s, a value comparable with those currently reported for biotrickling filters. The bacterial population in the acidic biofilter demonstrated capacity for removal of H₂S over a broad pH range (pH 1–7). A preliminary investigation into the different effects of bacterial biodegradation and carbon adsorption on system performance was also conducted. This study shows the HBF to be a feasible and economic alternative to physical and chemical treatments for the removal of H₂S.     

RNA干扰抑制TGF-βⅡ型受体的表达

目的:观察针对TGF-βRⅡ的干扰RNA对TGF-βRⅡ表达的抑制作用,探讨RNA干扰TGF-βRⅡ的方法对肾问质纤维化的抑制作用.方法:PCR方法扩增TGF-βRⅡ的cDNA序列,将全长的TGF-βRⅡ cDNA插入pcDNA3中,构建TGF-βRⅡ的真核表达栽体,酶切、测序及间接免疫荧光鉴定;根据TGF-βRⅡ的设计针对TGF-βRⅡ的干扰RNA,构建针对TGF-βRⅡ的RNA干扰质粒pSUPER-TGF-βR Ⅱ并进行酶切及测序鉴定;脂质体介导针对TGF-βR Ⅱ的RNA干扰质粒和TGF-β RⅡ的真核表达载体共转染293T细胞,western-blot检测293细胞内TGF-β R Ⅱ的表达.结果:pcDNA3-TGF-βRⅡ测序结果显示TGF-βRⅡ基因未发生突变.间接免疫荧光检测TGF-βRⅡ在293T细胞内的表达;测序显示RNA干扰质粒pSUPER-TGF-βRⅡ序列正确,RNA干扰质粒明显抑制293T细胞内TGF-βRⅡ的表达.结论:成功构建了TGF-βRⅡ的真核表达载体及针对TGF-βRⅡ的RNA干扰质粒,RNA干扰质粒能够抑制TGF-βRⅡ的表达,为进一步研究针对TGF-βRⅡ的RNA干扰对肾纤维化的预防及治疗作用提供有用工具.     

NL63冠状病毒木瓜样蛋白酶去泛素化酶活性和对宿主抗病毒天然免疫反应调节作用

引起人类呼吸道感染的冠状病毒已多达5种．冠状病毒与宿主相互作用决定了其致病性和免疫特性．冠状病毒感染后宿主会立即启动抗病毒天然免疫反应,而人类冠状病毒往往会编码特定蛋白逃逸或抑制宿主的天然免疫反应．NL63冠状病毒是一种新型人类冠状病毒,其非结构蛋白nsp3编码2个木瓜样蛋白酶(PLP)核心结构域PLP1和PLP2．前期研究发现,人类冠状病毒PLP2是一种病毒编码的去泛素化酶(DUB),但是对其DUB特性和功能还不清楚．研究发现,NL63冠状病毒PLP1和PLP2两个核心结构域中只有PLP2具有DUB活性,而且,PLP2的DUB活性对K48和K63连接的多聚泛素化修饰不表现明显特异性．同时,蛋白酶活性催化位点C1678和H1836突变后对其DUB活性有明显抑制作用,而蛋白酶活性催化位点D1849突变后对DUB活性无影响．其次,PLP2而非PLP1核心结构域能够明显抑制仙台病毒和重要信号蛋白(RIG-I、ERIS/STING/MITA)激活的干扰素表达,表明PLP2是一种冠状病毒编码的干扰素拮抗剂,而且PLP2的干扰素拮抗作用不完全依赖其蛋白酶活性．机制研究表明,PLP2能够与干扰素表达通路中的重要调节蛋白RIG-I和ERIS发生相互作用,通过对RIG-I和ERIS的去泛素化负调控宿主抗病毒天然免疫反应．此外,PLP2除利用DUB活性抑制干扰素表达外,很可能存在不依赖自身催化活性的其他组分共同抑制干扰素的产生．以上研究对阐明人类新发冠状病毒免疫和致病机理以及抗病毒药物研发具有重要参考价值．