A comparison of hemoglobins in five species of Microtus

The composition of tryptic peptides was determined for Hb (major or fast electrophoretic component) from four additional species of Microtus; M. p. pennsylvanicus, M. abbreviatus, M. miurus, and M. oeconomus, The amino acids from the four Hb were compared with Hb from M. p. tananaensis, and, on the basis of the combination of analyses for the several Hb. Ca 95% of the overall amino acid composition was considered. The compositions of most of the homologous peptides were identical, and two deletions in the sequence of 21 amino acids β 41–61 are believed to characterize the Hb of all four species. From differences in peptide composition the following substitutions were inferred. In the β chain, M. pennsylvanicus (2 ssp) differed from other species at two positions, 8: Ser vs Thr and 12: Thr vs Ash. In the β chain M. pennsylvanicus (2 ssp) differed from other species at two positions, β45: Phe vs Leu, and β50: Ser-Glx vs Thr. M. p. pennsylvanicus differed from M. p. tananaensis at position β88: Val-Leu vs Leu. All species showed ambiguity among the amino acids Ala-Ser-Phe-Leu centred presumably in positions β129 and β130. On the basis of an incomplete examination, the slow electrophoretic component of M. abbreviatus Hb could not be seen to differ from the fast component in its peptide map or in the general composition of its and β peptides.     

Functional expression of cDNAs for bovine 11 beta-hydroxylase-aldosterone synthases, P450(11 beta)-2 and -3 and their chimeras.

Two molecular species of bovine P450(11β), P450(11β)-2 and P450(11β)-3 have been identified, in which the amino acid differences were found at the 6th, 36th and 82nd positions from the NH₂-termini of the mature proteins. They catalyzed the 11β-, 18- and 19-hydroxylation and aldosterone formation from 11-deoxycorticosterone, and the rate of production of 18-hydroxycorticosterone and aldosterone by P450(11β)-3 was greater than that by P450(11β)-2 [Morohashi et al., J. Biochem. 107 (1990) 635–640].

In this study, chimeric clones were constructed whose 6th, 36th and 82nd amino acid residues were exchanged with each other. Two original clones and six chimeric clones were expressed in COS-7 cells, and their steroidogenic activities studied. The ratio of aldosterone or 18-hydroxycorticosterone production to corticosterone production by one clone was compared with that of the other. The ratios for the four clones having Gly36 [P450(11β)-3 type] were 0.08–0.22, whereas those for the clones having Ser36 [P450(11β)-2 type] were 0.03–0.05, suggesting that the Gly36 structure is important for aldosterone production.     

杜鹃花属植物的可育性研究进展

结合作者近年来的工作, 总结了国内外有关杜鹃花属(Rhododendron)植物可育性研究的成果和进展, 旨在为相关研究者和技术人员提供参考。(1)杜鹃花属的杜鹃亚属(subgen. Rhododendron)和羊踯躅亚属(subgen. Pentanthera)中存在多倍化现象, 甚至存在同一物种有多种倍性。(2)在自然授粉条件下, 除了常见种内杂交及自交情形外, 常绿杜鹃亚属(subgen. Hymenanthes)、杜鹃亚属和映山红亚属(subgen. Tsutsusi)内种间杂交十分普遍, 也有跨亚组之间的自然杂交案例。(3)杜鹃花属植物中自交亲和(self compatibility, SC)与自交不亲和(self incompatibility, SI)现象并存, 云锦杜鹃亚组(subsect. Fortunea)兼具自交败育到高可育性的所有类型, 而在映山红亚属与马银花亚属(subgen. Azaleastrum)中自交不亲和现象则更为常见。通常自交被认为是杜鹃花物种的被动适应, 但对于一些在极端气候条件下分布的局域种而言, 则可能是一种主动响应。(4)不同分类等级(亚属、组和亚组)间的人工杂交研究表明, 杂交亲和性或可育性与双亲的系统发育关系及染色体倍性具有明显的关联, 并反映在发育阶段和各项亲和力指标的变化之中。常绿杜鹃亚属与杜鹃亚属间的远缘杂交相对比较容易, 常绿杜鹃亚属与映山红亚属间、映山红亚属与杜鹃亚属的正反交、映山红亚属与羊踯躅亚属的正交以及常绿杜鹃亚属与羊踯躅亚属的正交、马银花亚属与杜鹃亚属正交等也有亲和的案例。(5)自交不亲和亲本的介入可大幅度增加种间杂交的不育比率, 并导致其由双向可育到单向不育再到双向不育方向发展。     

Main sterols from the ophiuroids Ophiocoma echinata, Ophiocoma wendtii, Ophioplocus januarii and Ophionotus victoriae

Sterol compositions of the cold water ophiuroids Ophioplocus januarii and Ophionotus victoriae and of the tropical ophiuroids Ophiocoma echinata and Ophiocoma wendtii are reported. The four sterol mixtures contain Δ⁵ mono- and di-unsaturated common 3β-hydroxy-sterols. Ophioplocus januarii and O. victoriae contain 24-methylcholesta-5,24(28)-dien-3β-ol and 24ζ-ethylcholesta-5,24(28)-dien-3β-ol in higher abundance than in O. echinata. These sterols were not found in O. wendtii. An interesting finding is the presence of Δ^5,24(28)-24-n-propylidenecholesterol in 7.6% in Ophionotus victoriae.     

Effects of electronic structure on chiral induction in outer-sphere electron transfer reactions of complexes with the C3 symmetric ligand, 1,4,7-triazacyclononane-1,4,7-tris[2′(R)-2′-propionate](-3)

The ligand 1,4,7-triazacyclononane-1,4,7-tris[2′(R)-2′-propionate](-3)((R)-tacntp³⁻), binds stereospecifically to transition metal ions. The structures of the complexes [Cr((R)-tacntp)]·NaBr and [Fe((R)-tacntp)]·H₂O have been determined by X-ray crystallography. Both complexes have the Λ-configuration but the conformation of the chelate rings in Λ-[Cr((R)-tacntp)] is (λ,λ,λ) with a geometry close to octahedral while in Λ-[Fe((R)-tacntp)] it is (δ,δ,δ) and the geometry is closer to that of a trigonal prism. Chiral induction in the electron transfer reactions of Λ-[Co((R)-tacntp)], Λ-[Fe((R)-tacntp)] and Λ-[Mn((R)-tacntp)] with [Co((RR,SS)-chxn)₃]²⁺ has been investigated. All three reactions are outer-sphere and four isomeric [Co((RR,SS)-chxn)₃]³⁺ products are identified in each case. The oxidants Λ-[Fe((R)-tacntp)] and Λ-[Mn((R)-tacntp)] show very similar selectivities, quite different from those of Λ-[Co((R)-tacntp)]. Reasons for this behavior are discussed.     

Oxidation of 1,4-alkanediols into γ-lactones via γ-lactols using Rhodococcus erythropolis as biocatalyst

Whole cells of Rhodococcus erythropolis DSM 44534 grown on ethanol, (R)- and (S)-1,2-propanediol were used for biotransformation of racemic 1,4-alkanediols into γ-lactones. The cells oxidized 1,4-decanediol (1a) and 1,4-nonanediol (2a) into the corresponding γ-lactones 5-hexyl-dihydro-2(3H)-furanone (γ-decalactone, 1c) and 5-pentyl-dihydro-2(3H)-furanone (γ-nonalactone, 2c), respectively, with an EE(R) of 40–75%. The transient formation of the γ-lactols 5-hexyl-tetrahydro-2-furanol (γ-decalactol, 1b) and 5-pentyl-tetrahydro-2-furanol (γ-nonalactol, 2b) as intermediates was observed by GC–MS. 1,4-Pentanediol (3a) was transformed into 5-methyl-dihydro-2(3H)-furanone (γ-valerolactone, 3c) whereas (R)- and (S)-2-methyl-1,4-butanediol (4a) was converted to the methyl-substituted γ-butyrolactones 4-methyl-dihydro-2(3H)-furanone (4c₁) and 3-methyl-dihydro-2(3H)-furanone (4c₂) in a ratio of 80:20 with a yield of 55%. Also cis-2-buten-1,4-diol (5a) was transformed resulting in the formation of 2(5H)-furanone (γ-crotonolactone, 5c). At the higher pH values of 8.8 the yield of lactone formed was improved; however, the enatiomeric excesses were slightly higher at the lower pH of 5.2.     

Triterpenoidal saponins from Dumasia Truncata

Extraction of the aerial parts of Dumasia truncata Sieb et Zucc. afforded two new triterpenoidal saponins, together with four known ones. The structures of the new compounds were elucidated by spectral analysis as 3-O--l-rhamnopyranosyl-(1 → 3)-β-d-glucuronopyranosy-28-O-β-d-glucopyransoyl hederagenin and 3-O-β-d-xylopyranosyl-(1 → 2)-[-l-rhamnopyranosyl(1 → 3)]-β-d-glucuronopyranosyl oleanic acid.     

Beta-ketothiolase genes in Azotobacter vinelandii

Azotobacter vinelandii is proposed to contain a single β-ketothiolase activity participating in the formation of acetoacetyl-CoA, a precursor for poly-β-hydroxybutyrate (PHB) synthesis, and in β-oxidation (Manchak, J., Page, W.J., 1994. Control of polyhydroxyalkanoate synthesis in Azotobacter vinelandii strain UWD. Microbiology 140, 953–963). We designed a degenerate oligonucleotide from a highly conserved region among bacterial β-ketothiolases and used it to identify bktA, a gene with a deduced protein product with a high similarity to β-ketothiolases. Immediately downstream of bktA, we identified a gene called hbdH, which encodes a protein exhibiting similarity to β-hydroxyacyl-CoA and β-hydroxybutyryl-CoA dehydrogenases. Two regions with homology to bktA were also observed. One of these was cloned and allowed the identification of the phbA gene, encoding a second β-ketothiolase. Strains EV132, EV133, and GM1 carrying bktA, hbdH and phbA mutations, respectively, as well as strain EG1 carrying both bktA and phbA mutations, were constructed. The hbdH mutation had no effect on β-hydroxybutyryl-CoA dehydrogenase activity or on fatty acid assimilation. The bktA mutation had no effect on β-ketothiolase activity, PHB synthesis or fatty acid assimilation, whereas the phbA mutation significantly reduced β-ketothiolase activity and PHB accumulation, showing that this is the β-ketothiolase involved in PHB biosynthesis. Strain EG1 was found to grow under β-oxidation conditions and to possess β-ketothiolase activity. Taken together, these results demonstrate the presence of three genes coding for β-ketothiolases in A. vinelandii.     

Selection and preliminary characterization of β-glycosidases producer Patagonian wild yeasts

Four pre-selected indigenous yeast strains belonging to Candida guilliermondii (V₂ and V₅), Candida pulcherrima (V₆) and Kloeckera apiculata (V₉), were used as β-glucosidase (βGL) and β-xylosidase (βXL) sources. The optimization of yeast culture conditions was carried out and the effects of oenological parameters on β-glycosidase activities were evaluated. C. guilliermondii V₂ and C. pulcherrima V₆ strains were selected. These strains showed intracellular (C. pulcherrima V₆) and parietal (C. guilliermondii V₂) constitutive βGL and βXL. The enzymatic activities were active at pH, glucose, ethanol and SO₂ concentrations usually found in winemaking and they were able to release monoterpenols and alcohols from grape juice glycoside extracts. Additionally, these yeast strains were not able to produce volatile acidity and off flavour. Regional ecological relevance of these species was also discussed. Our results evidence that the selected C. guilliermondii V₂ and C. pulcherrima V₆ strains have interesting oenological characteristics and allow us to think in their potential application in winemaking.     

Estimation of soluble β-glucan content of yeast cell wall by the sensitivity to Glucanex 200G treatment

The soluble β-glucan contents in the cell wall of yeasts were estimated by treating cells with Glucanex^® 200G that contained mainly β1,3-glucanase and some β1,6-glucanase. The sensitivity of cell walls of 11 yeasts to various concentrations of β-glucanase was compared. The yeasts that are resistant to β-glucanase treatment are expected to contain higher β-glucan content and those that are sensitive to the β-glucanase treatment are expected to contain lower β-glucan content. Two yeast strains were selected for further study by comparing the sensitivity of cell wall to β-glucanase; Candida bombicola and Candida albicans. Candida bombicola was more resistant and C. albicans was more sensitive to the Glucanex^® 200G treatment. The results of enzyme sensitivity tests were verified by quantification of soluble β-glucan content purified from the yeasts. Much larger amount of soluble β-glucan was obtained from the cell walls of C. bombicola (0.08 g g⁻¹ dried cell) than C. albicans (0.025 g g⁻¹ dried cell).     

Lipase-catalyzed kinetic resolutions of racemic β- and γ-thiolactones

Several racemic β- and γ-thiolactones were synthesized and kinetic resolutions of them were executed using lipases. While a lipase from Pseudomonas cepacia (PCL) showed the highest enantioselectivity for (S)-form (>99% ee_S at 53% conversion, E > 100) in the kinetic resolution of racemic -methyl-β-propiothiolactone (rac-MPTL), it showed no hydrolysis activity in the kinetic resolution of -benzyl--methyl-β-propiothiolactone (rac-BMPTL), suggesting that the changes in the size of alkyl group from rac-MPTL to rac-BMPTL leads to lower hydrolysis activity and enantioselectivity. In contrast, racemic γ-butyrothiolactones were hydrolyzed by several lipases with low enantioselectivity, whereas a lipase from Candida antarctica (CAL) showed moderate enantioselectivity for (S)-form (>99% ee_S at 76% conversion, E = 11) in the kinetic resolution of racemic -methyl-γ-butyrothiolactone (rac-MBTL). Computer-aided molecular modeling was also performed to investigate the enantioselectivites and activities of PCL toward β-propiothiolactones. The computer modeling results suggest that the alkyl side chains of β-propiothiolactones and γ-butyrothiolactones interact with amino acid residues around hydrophobic crevice, which affects the activity of PCL.     

梾木属四照花亚属的系统和总览

不同作者对四照花亚属的性状估价不同,因而对其下分类群的分类很不一致。本文据其不同的过冬习性和芽结构与地理分布相关联,建立了两个组、两个系的新系统。并根据"形态地理"学的方法,认为"种"是一组居群,与另一种在形态上需有间断区别,"亚种"是种的组成成分,有一定分布区(若是同域则占居不同生境),形态上有区别,但在分布区交接处有中间类型存在,"变种"是种内限于较狭分布区域成分散分布的变异类形;将该亚属由原来19个种处理成4个种,12个亚种及3个变种。     

Allelic variation in the cg2 gene does not correlate with chloroquine resistance among Indian Plasmodium falciparum isolates.

The cg2 gene of Plasmodium falciparum has been proposed to be associated with chloroquine resistance. Here we describe PCR amplification and sequencing of all the four repeat regions (kappa (κ), gamma (γ), psi (φ) and omega (ω)) of this gene, from Indian isolates. There were variant forms for each of these repeat regions (two for κ and γ, and three for φ and ω) among the 123 Indian isolates of P. falciparum. Among these isolates certain forms of φ and ω repeats were uniquely present while some of the reported forms of the κ and ω repeats were absent. The pattern of combination of all four repeat regions of cg2 gene (genotype) was analysed from 52 isolates. A total of 11 different genotypes were observed among these cases, of which 10 were unique to Indian isolates. Certain genotypes were more common than others. The nucleotide sequencing of all the four repeat regions revealed that Indian isolates have some unique repeating units within the γ and ω domains. Altogether, the PCR and sequencing results showed that there was an unrelatedness between cg2 repeats and chloroquine resistance.     

Ceriopsins A-D,diterpenoids from Ceriops decandra

Chemical examination of the ethyl acetate solubles of the CH₃OH:CH₂Cl₂ (1:1) extract of the roots of Ceriops decandra collected from Kauvery estuary resulted in the isolation of four new diterpenoids, ceriopsins A–D (1–4). The structures of the new diterpenoids were elucidated by a study of their physical and spectral data as methyl 17-hydroxy-16-oxobeyeran-18-oate (1), methyl 16(R)-16,17-dihydroxybeyeran-18-oate (2), 1β,15(S)-isopimar-7-ene-1,15,16-triol (3), and 8,15(R)-epoxypimarane-1β,16-diol (4).     

不同经营模式山核桃林地土壤pH值、养分与细菌多样性的差异

为探究土壤细菌多样性及其功能对山核桃(Carya cathayensis)经营模式的指导作用, 本文采用16S rRNA基因高通量测序技术检测并比较了生态经营和过度经营的山核桃林土壤中的细菌群落, 分析了山核桃干腐病发病期干腐病感病指数、土壤pH值、养分与细菌多样性的相关性。结果表明: (1)生态经营山核桃林的感病指数(3.3 ± 3.35)显著低于过度经营山核桃林(81.9 ± 1.27)。(2)生态经营山核桃林土壤pH (6.64 ± 0.06)显著高于过度经营山核桃林(5.80 ± 0.04)。(3)过度经营山核桃林土壤的速效磷、速效钾和速效氮含量分别为18.10 ± 0.58 mg/kg、698.63 ± 11.24 mg/kg和227.13 ± 3.81 mg/kg, 均分别显著高于三者在生态经营山核桃林土壤中的含量(14.94 ± 0.27 mg/kg、497.13 ± 6.19 mg/kg和195.28 ± 6.01 mg/kg)。(4)生态经营和过度经营山核桃林土壤分别有14和21个主要细菌属, 其中鞘氨醇单胞菌属(Sphingomonas)、Gaiella和溶杆菌属(Lysobacter)为生态经营山核桃林土壤的优势属, 其相对多度显著高于过度经营山核桃林; 而Bryobacter、Candidatus Solibacter和慢生根瘤菌属(Bradyrhizobium)为过度经营山核桃林土壤中的优势属, 其相对多度显著高于生态经营山核桃林。两种经营模式下山核桃林土壤的OTUs、Ace指数、Chao指数、Shannon指数和Simpson指数无显著差异。RDA分析与蒙特卡罗检验表明, pH值、速效磷和速效氮均对土壤细菌优势菌群群落结构有显著影响(P < 0.05)。     

Iridoid glucosides from Thunbergia laurifolia

Two iridoid glucosides, 8-epi-grandifloric acid and 3′-O-β-glucopyranosyl-stilbericoside, were isolated from the aerial part of Thunbergia laurifolia along with seven known compounds, benzyl β-glucopyranoside, benzyl β-(2′-O-β-glucopyranosyl) glucopyranoside, grandifloric acid, (E)-2-hexenyl β-glucopyranoside, hexanol β-glucopyranoside, 6-C-glucopyranosylapigenin and 6,8-di-C-glucopyranosylapigenin. Strucural elucidation was based on the analyses of spectroscopic data.     

紫陀螺菌化学成分及其抑制肿瘤细胞增殖活性的研究

以紫陀螺菌为对象,研究其子实体的化学成分及其抑制肿瘤细胞增殖活性。采用溶剂提取、柱层析和高效液相色谱等方法分离纯化化学成分,通过核磁共振和质谱技术鉴定单体化合物结构,运用结晶紫法评价单体化合物抑制肿瘤细胞增殖活性。从乙酸乙酯提取物中共分离鉴定6个单体化合物,分别为(22E,24R)-麦角甾-5,7,22-三烯-3β-醇(1)、3β,5α-二羟基-(22E,24R)-麦角甾-7,22-二烯-6-酮(2)、(22E,24R)-麦角甾-7,22-二烯-3β,5α,6β-三醇(3)、吲哚-3-甲酸甲酯(4)、4,4-二甲基-1,7-庚二酸(5)和(8E,10E)-12羰基十八碳-8,10-二烯酸(6),其中化合物1为主要成分,相对含量为23.8%。活性测试结果表明3对人乳腺癌细胞株MCF-7 细胞、人胰腺癌细胞株PANC-1细胞和人乳腺癌细胞株MDA-MB-231细胞具有微弱的细胞增殖抑制活性。本研究首次报道了紫陀螺菌化学成分,对深入挖掘其在健康领域中的开发价值具有重要意义。     

Evolution in Carex L. sect. Spirostachyae (Cyperaceae): A molecular and cytogenetic approach

Carex sect. Spirostachyae comprises 25 species displaying the centre of diversity in Eurasia. Phylogenetic analysis of the ITS nrDNA region of 20 species of sect. Spirostachyae, six species of sect. Ceratocystis, five species of sect. Elatae, and eight outgroup species reveals that neither sect. Spirostachyae nor sect. Elatae is monophyletic. With the exclusion of Carex cretica, the 19 species of sect. Spirostachyae studied form a clade with the five species of tropical-subtropical sect. Elatae. Taxonomy of the core Spirostachyae is not only mostly in agreement with our phylogenetic hypothesis, but also with ecological and new cytogenetic results. Two main groups with different chromosome numbers and edaphic preferences are identified in the core Spirostachyae. One includes primarily acidophilous species with high chromosome numbers (2n=(64)68–84), whereas the other one includes mainly basophilous species with lower chromosome numbers (2n=60–74(75)). Chromosome-number variation is extremely different in the core Spirostachyae, showing great stability in some widespread species (e.g. Carex extensa) but an active chromosome evolution – faster chromosomal rearrangements, fusion and fission events than ITS nucleotide substitutions – in more restricted species (e.g. Carex troodi). Biogeography of the two amphiatlantic pairs of species reveals two independent colonizations of South America from the European continent. The geographical barrier of the Strait of Gibraltar has played different roles in the course of evolution of this section, acting as an effective barrier to gene flow in one case (Carex helodes) but as a limited barrier or recent separation in two others (Carex distans, Carex punctata).