Estimating the age of the common ancestor of a sample of DNA sequences

We present a simple Monte Carlo method for estimating the age of the most recent common ancestor (MRCA) of a sample of DNA sequences. We show that Templeton's (1993) estimator of the age of the MRCA based on the maximum number of nucleotide differences between two sequences in a sample is inaccurate, and we demonstrate the new method by reanalyzing a sample of DNA sequences from human Y chromosomes and a sample of human Alu sequences.      

济南假单胞菌新种的抗生作用

从济南土壤中分离、筛选到Ps 161菌株。该菌株为革兰氏阴性需氧短杆菌,具有激活非蒋异性细胞免疫和特异性体液免疫的功能,能使机体获得免疫应答和免疫反应性。其菌苗对小鼠精原细胞、鼠类移植瘤有显著抑制作用,并增强吡喹酮治疗小鼠血吸虫童虫的作用。能提高人体白细胞和体液免疫功能,对人体癌性胸水和表浅转移癌实体瘤有明显的消除与抑制效果。该菌株的代谢产物对革兰氏阳性细菌有显著抑制作用。 经中国科学院徽生物研究所鉴定,该菌株为一新种,命名为济南假单胞菌(Pseudomonas tnanenses sp. Nov.)。     

寡核苷酸探针进行DNA指纹分析在法医学上应用的评价

本文用自制的寡核苷酸探针（ＣＡＣ）５／（ＧＴＧ）５,对与法医学应用有关的问题进行了研究。从室温下放置三年的血痕得到不完全的ＤＮＡ指纹图;从同一个体不同组织的ＤＮＡ得到完全一致的结果;从混合斑中分离出精子ＤＮＡ进行ＤＮＡ指纹检验,并与同一供体的血液ＤＮＡ指纹图进行比较;还仅有０．２５μｇ的ＤＮＡ获得了可分辨的ＤＮＡ指纹图。此外,用限制性内切酶ＨａｅⅢ代替Ｈｉｎｆｌ酶切入的基因组ＤＮＡ,也获得了高度多     

Synthesis of a coumarin based fluorescent amino acid

Summary l-2-amino-3-(6,7-dimethoxy-4-coumaryl)-propionic acid (l-Adp), as a non-proteinogenic fluorescent amino acid has been synthesized by a highly stereoselective routine (>99.5%). This fluorescent amino acid, as fluorophorequencher pair, may be used to study peptide assays. For enantiomeric excess determination, the racemicdl-Adp (dl-2-amino-3-(6,7-dimethoxy-4-coumaryl)-propionic acid) has also been synthesized.     

光催化纳米TiO2抗乙型肝炎病毒效果的实验研究

In this essay the destructive rates of HBsAg, the surface antigen of HBV, exposed to different light sources and photocatalysed time on both TiO2 ceramic plate and Ni net were investigated, the effect of anti-HBV of TiO2 was discussed under different light condition.The result demonstrated that ceramic TiO2 plate has 87.50% destructive rate under high Hg lamp irradiation(SμW/cm^2) after 4 hours,while the controlled normal ceramic almost had no influence to HBsAg. Also the result indicated that under indirect sunlight(20μW/cm^2) for 4 hours, plate with TiO2 destroyed 93.75% of the HBsAg but the ordinary plate destroyed 87.50%.The Ni net with TiO2, when placed under ultraviolet irradiation (480μW/cm^2)for 2,5,10 minutes destructive rates to HBsAg were 99.80%, 99.90%, and 100% respectively,but the controlled net without TiO2 thin film showed only 93.75% even after l0 minutes under the same ultraviolet.     

Identification and characterization of Lactic Acid Bacteria isolated from Tibetan Qula cheese

Fourteen strains of Lactic Acid Bacteria (LAB) isolated from Qula, a Tibetan traditional yak cheese, were divided into four groups (A-D) according to morphological and biochemical characteristics. On the basis of the 16S rRNA gene sequence analysis, group A and group B strains were placed in the cluster making up the genus Leuconostoc, which together with Leuconostoc mesenteroides and Leuconostoc pseudomesenteroides, formed a distinct cluster. The group C strain was clearly identified as Enterococcus faecium by forming a very well defined cluster with this species. The group D strains were placed in the lactobacilli cluster with Lactobacillus plantarum and Lactobacillus pentosus being the closely related species. On the basis of DNA-DNA hybridization, strains in the groups A, B, C and D were identified as Leuconostoc mesenteroides subsp. dextranicum, Leuconostoc pseudomesenteroides, Enterococcus faecium and Lactobacillus plantarum, respectively. Leuconostoc mesenteroides subsp. dextranicum was the dominate member of the population.     

Predicting the folding pathway of engrailed homeodomain with a probabilistic roadmap enhanced reaction-path algorithm

To predict a protein-folding pathway, we present an alternative to the time-consuming dynamic simulation of atomistic models. We replace the actual dynamic simulation with variational optimization of a reaction path connecting known initial and final protein conformations in such a way as to maximize an estimate of the reactive flux or minimize the mean first passage time at a given temperature, referred to as MaxFlux. We solve the MaxFlux global optimization problem with an efficient graph-theoretic approach, the probabilistic roadmap method (PRM). We employed CHARMM19 and the EEF1 implicit solvation model to describe the protein solution. The effectiveness of our MaxFlux-PRM is demonstrated in our promising simulation results on the folding pathway of the engrailed homeodomain. Our MaxFlux-PRM approach provides the direct evidence to support that the previously reported intermediate state is a genuine on-pathway intermediate, and the demand of CPU power is moderate.