云杉核型的研究兼论云杉属的进化地位

本文分析了我国特产树种云杉Picea asperata的核型,K(2n)=24=20m+4sm,属2A类型,染色体相对长度组成为2n=24=2L+12M_2+SM_1+2S。云杉属植物(22种、变种)的核型全由臂比小于2的中部和近中着丝粒染色体构成,是较为原始的核型。根据松科各属核型的比较,作者讨论了云杉属的亲缘关系和进化地位,并得到形态学、解剖学、孢粉学、植化学、生化学及古植物学等的支持。     

四种云杉的核型分析

首次报道了中国珍稀濒危保护植物长叶云杉 ( P. smithiana ( Wall.) Boiss.)和康定云杉 ( P. likian-gensis( Franch.) Pritz.var.montigena( Mast.) Cheng ex Chen)及我国特产的青海云杉 ( P.crassif oliaKom.)和林芝云杉 ( P.likiangensis( Franch.) Pritz.var.linzhiensis Cheng et L.K.Fu)的核型。它们的核型公式都是 K( 2 n) =2 4 =2 2 m+2 sm (林芝云杉有 1条 B染色体 ) ,染色体相对长度组成分别为 2 n=1 4 M2 +8M1 +2 S,2 L+1 2 M2 +6M1 +4S,2 L +1 0 M2 +1 0 M1 +2 S,和 2 L+1 2 M2 +6M1 +4S.均为 2 A (除青海云杉 1 A外 )核型类型。     

五种云杉的核型分析

作者分析了我国产的5种云杉的核型,结果如下:红皮云杉,2n=24=20m(4sc)+4sm;白扦2n=24=22m(6sc)+2sm+2B;青扦,2n=24=16m(6sc)+8sm+2B;雪岭杉2n=24=20m(6sc)+4sm;鱼鳞云杉,2n=24=22m(4sc)+2sm+1B。     

沙地云杉与其近缘种间的GISH分析

以沙地云杉(Picea mongolica(H.Q.Wu)W.D.Xu)、白杄(P.meyeri Rehd.et Wils.)、红皮云杉(P.koraiensis Nakai)3种云杉属植物为材料,利用基因组原位杂交技术(GISH),用白杄和红皮云杉基因组DNA分别作探针与沙地云杉中期染色体进行杂交,分析3种云杉的亲缘关系,旨在进一步探讨沙地云杉的起源。结果表明:(1)3种云杉的染色体数目均为2n=24,核型类型为1A,大部分染色体为亚中部着丝粒;白杄和红皮云杉核型不对称系数分别为57.78%、57.64%,小于沙地云杉(58.75%)。(2)以白杄基因组DNA为探针时,在沙地云杉14条染色体上有明显杂交信号,信号位点主要位于着丝粒区、次缢痕处和短臂部位;以红皮云杉DNA为探针时,12条染色体上有明显杂交信号,主要位于着丝粒区、次缢痕处和长臂上,杂交信号分布范围和强度明显弱于白杄。研究认为,沙地云杉与白杄的亲缘关系较近,而与红皮云杉较远,该研究首次阐明沙地云杉非起源于白杄和红皮云杉的种间杂交。     

野牡丹科6种植物染色体数目及核型分析

研究了野牡丹科国产野牡丹属(Melastoma L.)4种植物和从国外引种的蒂牡花属(Tibouchina Aubl.)2种植物的染色体数目,并对4种野牡丹属植物的核型进行分析。结果表明, 野牡丹属植物的染色体数目为2n=24,为二倍体植物,蒂牡花属的蒂牡花(T. urvillean)和银毛野牡丹(T. heteromall)的染色体数目为2n=36。核型公式为：野牡丹(M. malabathricum) 2n=10m(2SAT)+14sm;毛稔(M. sanguineurn) 2n=10m+12sm+2st;地稔(M. dodecandrum) 2n=12m+12sm;细叶野牡丹(M. intermedium) 2n=12m＋10sm+2st。核型分析表明国产野牡丹属植物染色体为小染色体,绝对长度为0.43~1.79 µm;核型不对称系数为59.47~62.91,均属2B型。野牡丹属植物的核型为首次报道。     

鸡骨常山属三个种的核形态

研究了鸡骨常山属（Alstonia）3个种的核形态,其中盆架树（A.rostrata）的核型属首次报道,3个种的体细胞染色体数目均为2n=42,且糖胶树（A.scholaris）和鸡骨常山（A.yunnanensis）的染色体数目同前人报道的2n=44不同。盆架树的间期核和有丝分裂前期染色体分别为棒状前染色体型和中间型,核型公式为2n=42=3M＋21m＋18sm,核型不对称性类型为2A型。糖胶树的间期核和有丝分裂前期染色体分别为球状前染色体型和中间型,核型公式为2n=42=14m＋24sm＋4st,核型不对称性类型为3A型。鸡骨常山的间期核和有丝分裂前期染色体分别为复杂染色体中央粒型和中间型,核型公式为2n=42=5m＋37sm,核型不对称性类型为3B型。根据核形态结果,结合形态学特征和已有的细胞学资料,初步讨论了该属几个种的系统位置及演化趋势。     

药用植物刺五加染色体核型分析

采用根尖压片技术对刺五加的细胞染色体计数,并对其进行了核型分析,结果表明：刺五加染色体数目为2n=48,染色体基数X=24。其中1对染色体上有随体,核型公式为：K（2n）=48=12m＋18sm（SAT）＋8st＋10t。染色体相对长度组成2n=4L＋22M2＋14M1＋8S,属于“3B”型。全组染色体总长30．82¨m,长臂总长22．88Dm,核型不对称系数为74．23％。     

基于荧光原位杂交技术的紫薇属植物核型分析

以紫薇(Lagerstroemia indica)、尾叶紫薇(L.caudata)、屋久岛紫薇(L.fauriei)和福建紫薇(L.limii)4种紫薇属植物为材料,利用染色体荧光原位杂交技术(FISH)获得了4种紫薇属植物的有丝分裂中期染色体FISH图及核型参数,分析了45SrDNA在紫薇属植物染色体上的数量和分布特点。结果表明,4种紫薇属植物染色体上均具有1对45SrDNA杂交位点,位于较长染色体短臂的近端部,紫薇、尾叶紫薇、屋久岛紫薇和福建紫薇的核型公式分别为2n=48=2M+24m+22sm、2n=48=30m+18sm、2n=48=2M+20m+26sm和2n=48=2M+32m+14sm,均为2A型。该研究首次获得了紫薇属植物45SrDNA荧光原位杂交核型,为紫薇属植物亲缘关系研究和细胞生物学研究提供了分子细胞学依据。     

六种云杉的核型分析

对６种（含１变种）云杉属植物的染色体数目及形态特征进行了分析研究。研究树种均为我国特有种,其中４种在本文中首次报道。分析材料全部取自各树种中心产区的原始林内。其核型公式：鳞皮云杉（Ｐ．ｒｅｔｒｏｆｌｅｘａ）Ｋ（２ｎ）＝２４＝２２ｍ＋２ｓｍ;云极（Ｐ．ａｓｐｅｒａｔａ）Ｋ（２ｎ）＝２４＝２０ｍ＋４ｓｍ;青插（Ｐ．ｗｉｌｓｏｎｉｉ）Ｋ（２ｎ）＝２４＝２０ｍ＋４ｓｍ＋１Ｂ;紫果云极（Ｐ．ｐｕｒｐｕｒｅａ     

横断山区石竹科细蝇子草的染色体数目及核型报道

报道了石竹科细蝇子草(Silene gracilicaulis)的染色体数目及核型。染色体数目2n=24,染色体核型公式为2n=2x=24=22m 2sm,属2A核型。     

Redox reactions obtained by gamma irradiation of quercetin methanol solution are similar to in vivo metabolism

The flavonol quercetin is one of the most well-known antioxidant flavonoids. Its antioxidant potential has been studied extensively during the last 10 years, but little is known about the metabolites formed in vivo that lead to the formation of depside and small molecules such as benzoic acids. In this study, gamma irradiation of a quercetin methanol solution was used as a model of certain oxidative reactions that occur in vivo. Qercetin at concentrations ranging from 5 x 10(-5) M to 5 x 10(-3) M, was irradiated with gamma rays at doses of 2-14 kGy. Quercetin degradation was evaluated by HPLC analysis. The major radiolytic metabolite was identified as a depside by NMR and LC-MS. Formation of 3,4-dihydroxybenzoic acid was also observed. The presence of CH3O. formed during methanol radiolysis is invoked to explain depside formation. Transformation of the 8-methoxy substituted depside (Q1) to the 8-hydroxyl substituted depside (Q2) is discussed. The antioxidant properties of quercetin metabolites are evaluated according to their capacity to decrease the EPR DPPH signal and to inhibit superoxide radical formed by the enzymatic reaction (xanthine + xanthine oxidase). For both assays, the IC50 of Q2 is twice as high as that of quercetin.     

NMR assignment of the absolute configuration of C-25 in furostanol steroidal saponins

The chemical shifts of the geminal proton resonances of H(2)-26 (δa and δb) are a widely used predictor of C-25 stereochemistry in furostanol steroidal saponins, being in general more resolved in 25S than 25R compounds. Unexpectedly, we found that application of this empirical rule in different solvents led to conflicting assignments of stereochemistry. An experimental survey revealed that, while the chemical shifts of H(2)-26 exhibit a dependence on C-25 configuration, it is less pronounced in methanol-d4 than pyridine-d5 solvent, and thus the general rule derived for pyridine-d5 fails when NMR spectra are acquired in methanol-d4. We propose a modified empirical method for the direct assignment of C-25 stereochemistry in furostanol saponins in methanol-d4 (Δ(ab)=0.45-0.48 ppm for 25S; Δ(ab)=0.33-0.35 ppm for 25R), and provide several detailed examples. In addition, the absolute configuration of compound 8, a steroidal saponin isolated in previous work from Ruscus colchicus, is corrected from 25R to 25S stereochemistry.     

Acute and joint toxicity of twelve substituted benzene compounds to Propsilocerus akamusi Tokunaga

This study investigated the toxic effects of 12 substituted benzenes exposed to Propsilocerus akamusi larvae singly and as mixtures. Their toxicities were quantified in terms of median effective concentration (EC₅₀) killing 50% of the larvae. For individual substituted benzenes to 4th-instar P. akamusi larvae, the toxicity was in decreasing order of p-chlorophenol > nitrobenzene > phenol > 1,2-dimethylbenzene > 1,3-dimethylbenzene > chlorobenzene > p-phenylenediamine > 1,4-dimethylbenzene > m-phenylenediamine > methylbenzene > benzene > aniline. The order of toxicity among three isomers of dimethylbenzene was 1,2-dimethylbenzene > 1,3-dimethylbenzene > 1,4-dimethylbenzene while p-phenylenediamine > m-phenylenediamine. The binary substituted benzene compounds’ toxicities were evaluated by toxic unit (TU), additive index (AI), mixture toxicity index (MTI) and similarity parameter index (λ). The evaluation results of TU and MTI for 9 substituted benzene compounds were completely consistent while the results of AI were the same as the results of λ based on 24 h EC₅₀ of binary substituted benzenes. The evaluation results of 10 substituted benzene compounds were consistent using TU, MTI, AI and λ evaluation methods. 52.63% and 47.37% of binary substituted benzene tests on P. akamusi larvae showed synergism and partial addition/antagonism, respectively, under mixtures of equal proportions. These results suggest that substituted benzenes indicate acute and binary joint toxicity to P. akamusi.     

NMR spectroscopy of the ring nitrogen protons of uracil and substituted uracils; relevance to Aψ base pairing in the solution structure of transfer RNA

The chemical shifts of the well-resolved ring nitrogen protons of uracil and a series of substituted uracils, including pseudouridine (5-ribosyl-uracil) and uridine (1-ribosyl-uracil) were determined using nuclear magnetic resonance (NMR). The observed chemical shifts suggest the existence of an atypical syn conformation for pseudouridine in the Aψ base pair in regulatory tRNAs in solution.     

Production of substituted catechols from substituted benzenes by a Pseudomonas sp.

In the presence of a halobenzene or benzonitrile, Pseudomonas T-12 can produce substituted catechols from the corresponding substituted benzenes. A variety of monosubstituted benzenes with substituents containing up to four carbons, and some meta- and para- disubstituted benzenes, can serve as catechol precursors.     

A strong 13C chemical shift signature provides the coordination mode of histidines in zinc-binding proteins

Zinc is the second most abundant metal ion incorporated in proteins, and is in many cases a crucial component of protein three-dimensional structures. Zinc ions are frequently coordinated by cysteine and histidine residues. Whereas cysteines bind to zinc via their unique S(γ) atom, histidines can coordinate zinc with two different coordination modes, either N(δ1) or N(ε2) is coordinating the zinc ion. The determination of this coordination mode is crucial for the accurate structure determination of a histidine-containing zinc-binding site by NMR. NMR chemical shifts contain a vast amount of information on local electronic and structural environments and surprisingly their utilization for the determination of the coordination mode of zinc-ligated histidines has been limited so far to (15)N nuclei. In the present report, we observed that the (13)C chemical shifts of aromatic carbons in zinc-ligated histidines represent a reliable signature of their coordination mode. Using a statistical analysis of (13)C chemical shifts, we show that (13)C(δ2) chemical shift is sensitive to the histidine coordination mode and that the chemical shift difference δ{(13)C(ε1)} - δ{(13)C(δ2)} provides a reference-independent marker of this coordination mode. The present approach allows the direct determination of the coordination mode of zinc-ligated histidines even with non-isotopically enriched protein samples and without any prior structural information.     

A NMR experiment for simultaneous correlations of valine and leucine/isoleucine methyls with carbonyl chemical shifts in proteins

A methyl-detected ‘out-and-back’ NMR experiment for obtaining simultaneous correlations of methyl resonances of valine and isoleucine/leucine residues with backbone carbonyl chemical shifts, SIM-HMCM(CGCBCA)CO, is described. The developed pulse-scheme serves the purpose of convenience in recording a single data set for all Ile^δ1, Leu^δ and Val^γ (ILV) methyl positions instead of acquiring two separate spectra selective for valine or leucine/isoleucine residues. The SIM-HMCM(CGCBCA)CO experiment can be used for ILV methyl assignments in moderately sized protein systems (up to ~100 kDa) where the backbone chemical shifts of ¹³C^α, ¹³C_β and ¹³CO are known from prior NMR studies and where some losses in sensitivity can be tolerated for the sake of an overall reduction in NMR acquisition time.     

用分子轨道法探讨油田废水中取代苯系物的毒性效应

采用半经验的分子轨道AM1方法中的MOPAC软件包计算了55种在油田废水中易于检出的取代苯系物的分子轨道能（EHOMO,ELUMO,ENHOMO,ENLUMO）、分子生成熟（△H^f0)和偶极矩（μ）等量化参数,结合一阶价分子连接性指数（^1X^V)和正辛醇／水分配系数(logP)与实验所得发光菌的半数活性浓度（EC50）成功建立了多参数定量－结构活性关系模式,在分类建模的基础上,又获得了仅包含1^X^V和EHOMO两个参数的55种取代苯系物的定量结构－活性相关模式,探讨了不同取代基的毒性作用机制,结果表明,量化参数与物化参数结合能够很好地预测油田废水中具有不同取代基团的取代苯系物的生物活性,预测模式中量子化学参数的出现有利于深入探讨油田废水中有机污染物的毒性效应。     

NMR characterization of the electrostatic interaction of the basic residues in HDGF and FGF2 during heparin binding

Electrostatic interaction is a major driving force in the binding of proteins to highly acidic glycosaminoglycan, such as heparin. Although NMR backbone chemical shifts have generally been used to identify the heparin-binding site on a protein, however, there is no correlation between the binding free energies and the perturbed backbone chemical shifts for individual residues. The binding event occurs at the end of a side chain of basic residue, and does not require causing significant alterations in the backbone environment at a distance of multiple bonds. We used the H₂CN NMR pulse sequence to detect heparin binding through the side-chain resonances Hε–Cε–Nζ of Lys and Hδ–Cδ–Nε of Arg in the two proteins of hepatoma-derived growth factor (HDGF) and basic fibroblast growth factor (FGF2). H₂CN titration experiments revealed chemical shift perturbations in the side chains, which were correlated with the free energy changes in various mutants. The residues K19 in HDGF and K125 in FGF2 demonstrated the most significant perturbations, consistent with our previous observation that the two residues are crucial for binding. The result suggests that H₂CN NMR provides a precise evaluation for the electrostatic interactions. The discrepancy observed between backbone and side chain chemical shifts is correlated to the solvent accessibility of residues that the K19 and K125 backbones are highly buried with the restricted backbone conformation and are not strongly affected by the events at the end of the side chains.     

Induced circular dichroism of cycloamylose complexes with meta- and para-disubstituted benzenes

Cycloamylose complexes with substituted benzenes in aqueous solutions were investigated by circular dichroism (CD) spectroscopy. The differences in CD spectra between cyclohexaamylose complexes and cycloheptaamylose complexes suggests that the orientation and disposition of the guest molecule differ in these two cycloamylose complexes. It was shown theoretically that the sign and intensity of CD are quite sensitive to the orientation of the guest chromophor in the cycloamylose cavity, but that the difference between the cyclohexaamylose complex and the cycloheptaamylose complex is only 13% if the guest molecule is included in the same geometry. Molecular ellipticity and thermodynamic parameters, which were determined by the least-squares curve-fitting procedure, indicate that the guest molecule is more closely packed in the cyclohexaamylose cavity, and that there is no stereospecificity in the complex formation between the meta-disubstituted benzenes and the para-disubstituted benzenes.