Ⅱ型限制性核酸内切酶NcrⅠ的研究

 在肉色诺卡氏菌C-212株Nocardia carnea C-212中筛选到一种Ⅱ型限制性核酸内切酶NcrⅠ,经与BglⅡ的λDNA降解物的酶谱比较,以及酶识别特异性和切割位点的检测,证明了NcrⅠ是已知的限制酶BglⅡ的同切限制酶,而且其切割位点也与BglⅡ相同,其为:     

Stationary phase-associated protein expression in Mycobacterium tuberculosis: function of the mycobacterial alpha-crystallin homolog.

The majority of active tuberculosis cases arise as a result of reactivation of latent organisms which are quiescent within the host. The ability of mycobacteria to survive extended periods without active replication is a complex process whose details await elucidation. We used two-dimensional gel electrophoresis to examine both steady-state protein composition and time-dependent protein synthetic profiles in aging cultures of virulent Mycobacterium tuberculosis. At least seven proteins were maximally synthesized 1 to 2 weeks following the end of log-phase growth. One of these proteins accumulated to become a predominant stationary-phase protein. N-terminal amino acid sequencing and immunoreactivity identified this protein as the 16-kDa alpha-crystallin-like small heat shock protein. The gene for this protein was shown to be limited to the slowly growing M. tuberculosis complex of organisms as assessed by Southern blotting. Overexpression of this protein in wild-type M. tuberculosis resulted in a slower decline in viability following the end of log-phase growth. Accumulation of this protein was observed in log-phase cultures following a shift to oxygen-limiting conditions but not by other external stimuli. The protein was purified to homogeneity from overexpressing M. smegmatis in two steps and shown to have a significant ability to suppress the thermal denaturation of alcohol dehydrogenase. Collectively, these results suggest that the mycobacterial alpha-crystallin protein may play a role in enhancing long-term protein stability and therefore long-term survival of M. tuberculosis.     

Structure and dynamics of melittin in lysomyristoyl phosphatidylcholine micelles determined by nuclear magnetic resonance.

Mixed micelles of the 26-residue, lytic peptide melittin (MLT) and 1-myristoyl-2-hydroxyl-sn-glycero-3-phosphocholine (MMPC) in aqueous solution at 25 degrees C were investigated by (13)C- and (31)P-NMR spectroscopy. (13)C alpha chemical shifts of isotopically labeled synthetic MLT revealed that MLT in the micelle is predominantly alpha-helical and that the peptide secondary structure is stable from pH 4 to pH 11. Although the helical transformation of MLT as determined from NMR is evident at lipid:peptide molar ratios as low as 1:2, tryptophan fluorescence measurements demonstrate that well-defined micellar complexes do not predominate until lipid:peptide ratios exceed 30:1. (31)P linewidth measurements indicate that the interaction between phosphate ions in solution and cationic groups on MLT is pH dependent, and that the phosphoryl group of MMPC senses a constant charge, most likely +2, on MLT from pH 4 to pH 10. (13)C-NMR relaxation data, analyzed using the model-free formalism, show that the peptide backbone of MLT is partially, but not completely, immobilized in the mixed micelles. Specifically, order parameters (S(2)) of C alpha-H vectors averaged 0.7 and were somewhat larger for residues in the N-terminal half of the molecule. The amino terminal glycine had essentially the same range of motion as the backbone carbons. Likewise, order parameters for the trp side chain were similar to those found for the peptide C alpha moieties, as was verified by trp fluorescence anisotropy decay data. In contrast, the motion of the lysine side chains was less restricted, the average S(2) values for the C epsilon-H vectors being 0.19, 0.30, and 0.44 for lys-7, 21, and 23, respectively, for MLT in the mixed micelles. Values of the effective correlation time of the local motion tau e were in the motional narrowing limit and usually longer for side-chain atoms than for those in the backbone. The dynamics were independent of pH from pH 4 to pH 9, but at pH 11 the correlation time for the rotational motion of the mixed micelles as a whole increased from 10 ns to 16 ns, and S(2) for the lys side chains increased. Overall it appears that the MLT helix lies near the surface of the micelle at low to neutral pH, but at higher pH its orientation changes, accompanied by deeper penetration of the lysine side chains into the micelle interior. It is apparent, however, that the MLT-lipid interaction is not dependent on deprotonation of any of the titratable cationic groups in the peptide in the pH 4-10 range, and that there is substantial backbone and side-chain mobility in micelle-bound MLT.     

FIBONACCI级数与菊花结构规律的研究

本文论证了菲波纳斯（Fibonacci）级数与菊花花冠结构的关系,发现了花冠的通用数学模式：花冠（数目）＝（5×倍数）十F_n（F_(n－1)＋F_(n-2)）     

Thermophilic glucoamylase from Talaromyces flavus

The heat-resistant mold, Talaromyces flavus , was found to produce a thermophilic glucoamylase that exhibited the highest activity at 50°C and in the pH range of 4.0–4.8. The K _m and V _max values of the crude enzyme for amylopectin were 0.21% and 16.7 mg glucose 1^-1, min^-1, respectively. The molecular weight of the enzyme as estimated by the gel filtration method was 42 kDa.     

草鱼染色体的包装（间期—中期）

以草鱼ＺＣ７９０１细胞株为材料,观察鱼类细胞从间期染色质到中期染色体的包装过程。主要通过（１）分裂期与间期细胞融合,诱导染色体早熟凝集;（２）染色体“伸长”处理;（３）培养细胞的低渗处理;（４）染色质辅展等方法,制作染色体标本,进行扫描和透射电镜观察。观察表明,鱼类染色质的基本结构与哺乳类细胞相同,也是直径约１０ｎｍ的核丝。染色体的色装有两种形式：一种是多级螺旋化形成直径约３００ｎｍ的染色单体,     

骨缘当归的化学成分

骨缘当归Angellica cartilaginomarginata var.foliata Yuan et Shen,别名:山藁本、野芹菜（江苏）,仅分布于江苏和浙江。在江苏镇江等地用干燥全草作山藁本入药,其化学成分未见报道。 样品采自江苏省句容县。将干根磨粉,提取物经中性氧化铝层析,根据色谱及光谱鉴定为两种脂肪酸、四种已知香豆素和一种植物甾醇即:正葵酸（n-capric acid）、月桂酸（lauric acid）、骨缘当归素（cartilaginomarginadin）、蝉翼素（pteryxin）、白花前胡素F（praeruptorin F）、佛手柑内酯（bergapten）及β-谷甾醇（β-sitosterol）。     

LDL的氧化修饰和氧化修饰LDL的组成和结构变化

与低密度脂蛋白(LDL)相比,氧化修饰LDL(O-LDL)的组成、结构和生物学特性发生了深刻的变化,而组成和结构的改变是生物学特性改变的基础.本文根据最近文献资料.结合我们实验室的工作.对LDL的氧化修饰、O-LDL的组成、结构改变,以及它们的机理作一简要综述.     

杨树拟茎点菌溃疡病的研究

本病系我国杨树新发生的一种病害。病原菌的分生孢子有2种形状,无色透明、单胞,呈纺缍形孢子大小为1.64—2.74×9.59—13.7μm。线形孢子顶端弯钩状大小为1.37—1.78×15—27.4μm。病原菌适宜生长的培养基为PDA、麦芽粉、豆饼粉培养基;温度为25—32℃和pH6—10。本病于4月下旬发病,5月中下旬分生孢子成熟,6月中下旬为分生孢子飞散高峰期。经室内采用多菌灵、甲基托布津、福美砷的200倍液浸泡插穗30、60、90分钟处理均有药害,采用100—200倍液浸泡10分钟无药害,对病害有防效。造林地幼树可采用上述药剂的100倍液进行刮破病斑涂抹,防效可达87.5％。