体外模拟人体细胞癌变的进展

癌症的发生是一个多基因决定和多阶段演进的过程 ,首先是某些基因发生突变并不断积累 ,引起细胞分化生长失控。然而这些突变必须克服机体设置的细胞增殖障碍、应激产生的染色体基因修补机制以及多种抑癌基因的作用。在染色体受到损伤时 ,这些抑癌因子会激活表达 ,调控基因转录以抑制肿瘤生长 ,所以只有当排除了抑癌因子的多重作用后 ,一个正常细胞才能逐渐突破防线而转化成为一个肿瘤细胞[1] 。经过多年研究 ,科学家虽已搞清了主导肿瘤转化的相关基因及其在转化过程中所起的作用 ,但能否根据这些已经了解的细胞转化机制 ,在体外模拟肿瘤的发…     

蓼属-未知花粉类型外壁超微结构的研究

花粉壁的构造提供了若干在系统发育上有用的特征,其中外壁的层次、结构以及纹饰是基本的。为此,本文以花粉壁的外部纹饰和内部结构为重点,用扫描电镜（ＳＥＭ）和透射电镜（ＴＥＭ）的薄切片技术,对蓼属一新的花粉类型－－长花蓼型的花粉外壁构造的特点进行了观察和研究。结果表明：外壁结构分化成两个明显的层次,即外面的外壁外层以及内面的外壁内层,其外壁外层无覆盖层,仅由柱状层和底层组成的。     

花生根瘤菌的抗逆性初步研究*

对３９株花生根瘤菌（其中６株为引进菌株）和９株参比菌株进行干旱、ＮａＣｌ、ｐＨ及低温的耐受性实验。结果表明我国花生根瘤菌资源中存在着耐盐、酸较强的菌株,且耐受性水平差异较大;在８℃条件下供试菌株未见生长;花生根瘤菌有着比大豆根瘤菌更强的抗干旱能力,抗干旱能力同耐盐能力之间没有明显的关系。另外,菌株的抗逆性同共生特性、分离地之间也未见有明显的关系。     

盐藻基因组DNA文库的构建(英文)

以ＬａｍｂｄａＦＩＸ○ＲⅡ为载体,构建了盐藻（Ｄｕｎａｌｉｅｌｌａｓａｌｉｎａ）的基因组文库。该文库包含了１．１×１０６个重组子,插入片段平均大小为１８ｋｂ左右,含插入片段的频率为１００％。该文库的容量约为盐藻单倍体基因组的２００倍。     

Structure and Specificity of the Bacterial Cysteine Methyltransferase Effector NleE Suggests a Novel Substrate in Human DNA Repair Pathway

Enteropathogenic E. coli (EPEC) and related enterobacteria rely on a type III secretion system (T3SS) effector NleE to block host NF-κB signaling. NleE is a first in class, novel S-adenosyl-L-methionine (SAM)-dependent methyltransferase that methylates a zinc-coordinating cysteine in the Npl4-like Zinc Finger (NZF) domains in TAB2/3 adaptors in the NF-κB pathway, but its mechanism of action and other human substrates are unknown. Here we solve crystal structure of NleE-SAM complex, which reveals a methyltransferase fold different from those of known ones. The SAM, cradled snugly at the bottom of a deep and narrow cavity, adopts a unique conformation ready for nucleophilic attack by the methyl acceptor. The substrate NZF domain can be well docked into the cavity, and molecular dynamic simulation indicates that Cys673 in TAB2-NZF is spatially and energetically favorable for attacking the SAM. We further identify a new NleE substrate, ZRANB3, that functions in PCNA binding and remodeling of stalled replication forks at the DNA damage sites. Specific inactivation of the NZF domain in ZRANB3 by NleE offers a unique opportunity to suggest that ZRANB3-NZF domain functions in DNA repair processes other than ZRANB3 recruitment to DNA damage sites. Our analyses suggest a novel and unexpected link between EPEC infection, virulence proteins and genome integrity.     

Application of quantitative structure‐activity relationship analysis on an antibody and alternariol‐like compounds interaction study

The antigen‐antibody interaction determines the sensitivity and specificity of competitive immunoassay for hapten detection. In this paper, the specificity of a monoclonal antibody against alternariol‐like compounds was evaluated through indirect competitive ELISA. The results showed that the antibody had cross‐reactivity with 33 compounds with the binding affinity (expressed by IC₅₀) ranging from 9.4 ng/mL to 12.0 μg/mL. All the 33 compounds contained a common moiety and similar substituents. To understand how this common moiety and substituents affected the recognition ability of the antibody, a three‐dimensional quantitative structure‐activity relationship (3D‐QSAR) between the antibody and the 33 alternariol‐like compounds was constructed using comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA) methods. The q² values of the CoMFA and CoMSIA models were 0.785 and 0.782, respectively, and the r² values were 0.911 and 0.988, respectively, indicating that the models had good predictive ability. The results of 3D‐QSAR showed that the most important factor affecting antibody recognition was the hydrogen bond mainly formed by the hydroxyl group of alternariol, followed by the hydrophobic force mainly formed by the methyl group. This study provides a reference for the design of new hapten and the mechanisms for antibody recognition.     

鲸类二次水生生境适应Epac1和Epac2基因的分子进化

心率即心脏跳动的速度,不仅反映了心脏的功能,还与寿命的长短及能量代谢有关。与大多数陆生哺乳动物相比,鲸类心率显著降低。降低的心率有助于鲸类寿命的延长及能量的高效利用,便于其适应极端的海洋环境,而这一适应的分子机制尚不清楚。鉴于此,本研究采用基于最大似然法的枝模型、枝位点模型结合蛋白质功能差异分析等方法,对控制心率的环状腺苷酸结合蛋白（Epac1 和Epac2）基因进行适应性探究。分析结果表明,Epac1在长寿鲸类即须鲸类和抹香鲸（Physeter macrocephalus）组合进化支中检测到加速进化过程,且枝位点模型在须鲸类祖先支中检测到的强烈的正选择位点均位于功能重要的催化区;另外,该蛋白质在鲸类中还发生了显著的功能修饰（θ=0.5296 ± 0.1300;P<0.001）。对Epac2进行相同的分析发现,该基因在寿命长达200年之久的弓头鲸（Balaena mysticetus）中检测到的正选择位点同样位于功能重要的催化区。上述结果提示Epac1和Epac2在鲸类中均产生了适应性进化,这一方面可能有助于鲸类心率降低,另一方面也可能与其较长的寿命及高效的能量利用有关。     

间断下体负压暴露方式对下体负压耐力的影响

目的：探讨不同方式反复下体负压锻炼对下体负压耐力的影响,以期筛选最佳的负压锻炼方式。方法：27名男性健康受试者随机分成3组,分别进行－5.33kPa8min(A组）、6.67kPa4min（B组）、6.67kPa8min（C组）的下体负压锻炼后累积应激指数（CSI）、总耐受时间（DNP）较锻炼前显著提高,A、B组上述指标无显著变化,下体负压暴露时的心率较平静状态显著升高,收缩压显著降低,舒张压无显著变化。结论：经过－6.67kPa/d8min连续8d的间断下体负压可以显著提高下体负压耐力。