产氢红杆菌类胡萝卜素含量和组分分析

类胡萝卜素在调节光合细菌产氢中具有重要作用。采用丙酮-甲醇有机溶剂法和KOH甲醇皂化法对产氢红杆菌(Rhodobacter sp.)R7菌株类胡萝卜素进行了提取纯化,并进一步采用硅胶G薄板层析法对提取的类胡萝卜素进行了分离,并结合光谱法对分离的类胡萝卜素进行了定性和定量分析。结果表明,丙酮-甲醇(7∶2,V/V)提取3次可将色素提取完全;最佳提取时间为2h;超声波处理与否对提取率影响不明显;该工艺提取类胡萝卜素产率为2.81mg/g湿菌体。硅胶G薄板层析表明该菌株类胡萝卜素有4个主要组分:黄色、红色、浅红色和浅黄色,黄色和红色为主要成分,光谱学数据显示黄色组分为球形烯,红色组分为螺菌黄质系类胡萝卜素,表明产氢红杆菌类胡萝卜素代谢途径独特。     

一株节杆菌发酵产物中类胡萝卜素的分离及组分分析的初探

【目的】对实验室保存的一株红色球菌进行菌株鉴定,并对色素提取液的组分进行定性分析。【方法】采取形态学观察、16S rDNA序列同源性分析和生理生化分析相结合的方法确定菌株的分类地位。使用乙醇-丙酮混合液提取胞内色素,采用硅胶G薄板层析法对色素提取液进行初步分离纯化,并结合其光谱吸收特性、质谱结果进行定性分析。【结果】实验结果表明此菌株属于节杆菌属(Arthrobacter sp.)。薄板层析结果显示该菌株内主要有4种色素组分,且靠近溶剂前沿组分为黄色,其它组分皆为橘红色。吸收光谱特性、质谱结果显示黄色组分可能为β-胡萝卜素,橘红色组分可能为螺菌黄质系类胡萝卜素。【结论】此株节杆菌以较为廉价的糖蜜和玉米浆作为营养物质用于满足自身生长需要,并且积累胞内类胡萝卜素,因此该菌的进一步研究有一定的价值。     

产氢红杆菌类胡萝卜素突变株的诱变和筛选

用紫外线照射和氯化锂夹层平板培养法对产氢红杆菌(Rhodobacter sp. R7)进行复合诱变, 分离获得了一株产氢效率提高的类胡萝卜素突变株R726。该突变株在表观特征、光谱学特征、色谱特征、生长和产氢性能等方面与出发菌株有明显不同, 但16S rDNA序列一致。R726菌株有 550 nm类胡萝卜素特征性吸收峰, 类胡萝卜素组成上比出发菌株少一黄色类胡萝卜素组分, 生长和产氢性能均高于出发菌株, 产氢效率比出发菌株提高了33.3%, 类胡萝卜素含量比出发株提高了53.8%。     

产氢红杆菌类胡萝卜素突变株的诱变和筛选

用紫外线照射和氯化锂夹层平板培养法对产氢红杆菌(Rhodobacter sp.R7)进行复合诱变,分离获得了一株产氢效率提高的类胡萝卜素突变株R726.该突变株在表观特征、光谱学特征、色谱特征、生长和产氢性能等方面与出发菌株有明显不同,但16S rDNA序列一致.R726菌株有550 nm类胡萝卜素特征性吸收峰,类胡萝卜素组成上比出发菌株少一黄色类胡萝卜素组分,生长和产氢性能均高于出发菌株,产氢效率比出发菌株提高了33.3%,类胡萝卜素含量比出发株提高了53.8%.     

类胡萝卜素在耐辐射奇球菌辐射抗性中的作用

为研究耐辐射奇球菌(Deinococcus radiodurans)中类胡萝卜素的生化合成基因及其在该细菌抗辐射机制中的生物学作用,通过有机溶剂提取及LC-MS技术分析了D. radiodurans所产类胡萝卜素物质的主要组分,运用PCR及基因同源重组技术,对该菌中类胡萝卜素生化合成途径的八氢番茄红素合成酶(phytoene synthase,crtB)及八氢番茄红素脱氢酶(phytoene desaturase,crtI)基因进行了缺失突变,通过表型观察及HPLC定量分析突变株所产类胡萝卜素的组分变化确证突变株构建成功．野生株及crtB 与crtI基因缺失突变株对电离辐射和H₂O₂的敏感性差异比较分析显示,和野生株相比,两种突变株对不同剂量电离辐射和不同浓度H₂O₂的敏感性更强．crtB及crtI基因功能研究表明,这两个关键性合成基因的缺失,导致突变株不能催化合成类胡萝卜素生化合成途径中的重要中间体——番茄红素及一系列下游产物．通过λ原噬菌体紫外线诱导系统、电子自旋共振 (ESR)及DMPO自旋捕集技术,分别在体内和体外评价了其类胡萝卜素的抗氧化能力．结果表明,两种类胡萝卜素对超氧阴离子(O₂^·)及羟自由基(·OH)均表现出较强的清除作用．上述研究结果为探究D. radiodurans的类胡萝卜素合成基因和生物学功能,及类胡萝卜素在D. radiodurans抗辐射机制中的作用提供了新的直接实验证据．     

过表达乙酰辅酶A乙酰基转移酶2基因(RKAcat2)对红冬孢酵母产类胡萝卜素的影响

[背景] 乙酰辅酶A乙酰基转移酶（Acetyl Coenzyme A Acyltransferase,Acat）是硫解酶家族的一员,分为I型和II型,而II型作为甲羟戊酸（Mevalonate,MVA）途径的第一个限速酶,其表达水平和催化活性会影响萜类及其衍生物的合成量。[目的] 分析Acat II型基因的过表达对红冬孢酵母产类胡萝卜素的影响。[方法] 从红冬孢酵母YM25235菌株中克隆编码Acat II型的基因RKAcat2,将其回转到红冬孢酵母YM25235菌株中,构建一株RKAcat2基因过表达菌株进行分析。[结果] 与对照菌株相比,RKAcat2基因过表达使YM25235菌株中类胡萝卜素含量提高了50.53%,而菌株中油脂含量降低了22.80%,脂肪酸组成中油酸含量显著下降了17.78%,而且菌株中乙酰辅酶A （Coenzyme A,CoA）的含量也下降了13.64%。[结论] 过表达RKAcat2基因促进更多乙酰CoA进入MVA途径中,从而提高了类胡萝卜素的合成水平,这与部分MVA途径和类胡萝卜素合成途径中基因的转录分析结果一致。研究结果可为进一步通过代谢工程手段提高产油红酵母中类胡萝卜素及其特定组分含量的研究提供参考。     

产氢菌Enterobacter sp.和Clostridium sp.的分离鉴定及产氢特性

在高温水体中分离得到2株具有较高产氢活性的微生物菌株Z-16和C-32。根据两菌株的16S rDNA序列分析,初步鉴定菌株Z-16为Enterobacter sp.,菌株C-32为Clostridium sp.。研究了起始pH值、反应温度、碳源等对菌株放氢活性的影响。菌株Z-16的最适产氢条件为：反应系统起始pH7.0,反应温度35℃,以蔗糖为产氢底物。在最适条件下,菌株Z-16的氢转化率为2.68mol H₂/mol蔗糖。菌株C-32的最适产氢条件为：反应系统起始pH 8.0,反应温度35℃,以麦芽糖为产氢底物。在最适条件下,菌株C-32的氢转化率为2.71mol H₂/mol 麦芽糖。以葡萄糖为碳源时,菌株Z-16和菌株C-32的氢转化率分别为2.35和2.48mol H₂/mol葡萄糖。     

产氢菌Enterobacter sp.和Clostridium sp.的分离鉴定及产氢特性

在高温水体中分离得到2株具有较高产氢活性的微生物菌株Z-16和C-32。根据两菌株的16S rDNA序列分析,初步鉴定菌株Z-16为Enterobacter sp.,菌株C-32为Clostridium sp.。研究了起始pH值、反应温度、碳源等对菌株放氢活性的影响。菌株Z-16的最适产氢条件为：反应系统起始pH7.0,反应温度35℃,以蔗糖为产氢底物。在最适条件下,菌株Z-16的氢转化率为2.68mol H₂/mol蔗糖。菌株C-32的最适产氢条件为：反应系统起始pH 8.0,反应温度35℃,以麦芽糖为产氢底物。在最适条件下,菌株C-32的氢转化率为2.71mol H₂/mol 麦芽糖。以葡萄糖为碳源时,菌株Z-16和菌株C-32的氢转化率分别为2.35和2.48mol H₂/mol葡萄糖。     

枫香秋季变色期叶色变化及其生理基础

为探究秋季枫叶呈色的关键生理因素,该文以转色期叶色为绿色、黄色和红色的枫香单株为试材,研究了L^*、a^*、b^*值变化与叶片色素、可溶性糖及可溶性蛋白质含量变化的相关性。结果表明:(1)在变色期,3种色彩枫香叶片叶绿素a、叶绿素b、总叶绿素和类胡萝卜素均大量降解,花色素苷不同程度积累。(2)绿色叶单株叶绿素和类胡萝卜素始终保持较高含量,花色素苷含量上升4.2倍,叶片内色素含量比值始终保持稳定; 黄色叶单株叶绿素和类胡萝卜素含量最低,花色素苷含量上升4.4倍,b^*值与叶绿素含量极显著负相关,与类胡萝卜素含量显著负相关,与花色素苷/类胡萝卜素含量比值极显著正相关; 红色叶单株叶绿素和类胡萝卜素含量略高于黄色叶单株,花色素苷含量上升27.2倍,a^*值与叶绿素含量、类胡萝卜素含量极显著负相关,与花色素苷含量显著正相关,与色素含量比值无显著相关性。(3)红色叶单株具有较高的可溶性糖含量和可溶性蛋白质含量。因此,在枫香叶片变色期,保持较高的叶绿素和类胡萝卜素含量,维持色素含量比值稳定使叶片呈现绿色; 叶绿素和类胡萝卜素的大量降解,以及花色素苷/类胡萝卜素含量比值的升高使叶片呈现黄色; 叶绿素的降解和花色素苷的大量合成使叶片呈现红色。     

红酵母属RY菌株形成类胡萝卜素的研究

分离的红酵母属（Rhodotorula）RY菌株形成的色素组成简单,石油醚可萃取到较纯的一种主要组分──红色的多烯类类胡萝卜素。该菌的培养条件为：葡萄糖2％,硫酸铵1％,酵母膏0．3％,添加2×10^－6mol／L核黄素,初始pH6．0,28℃,160r／min振荡培养72h。添加核黄素可以明显促进该菌类胡萝卜素的形成。     

Systematic significance of mature embryo of bamboos

The mature embryo of seven species belonging to five genera of Indian bamboos is described. In all these the basic pattern of embryo organisation is same: the scutellar and coleoptilar bundles are not separated by an internode, the epiblast is absent, the lower portion of the scutellum and the coleorhiza are separated by a cleft and the margins of embryonic leaves overlap. The features unique to fleshy fruited bamboos are: presence of a massive scutellum, the juxtaposition of plumule and radicle and the occurrence of a bud in the axil of the coleoptile. The fleshy fruit bearing bamboos should be classified into one group, the tribeMelocanneae. Evidence is provided to recognise additional groups in the subfamilyBambusoideae.     

Taxonomic status of the species of the green algal genusNeochloris

Komárek has recently reviewed the various species assigned to the green algal genusNeochloris Starr (Chlorococcales, Chlorococcaceae) and removed those with uninucleate vegetative cells to a new genus,Ettlia. Watanabe & Floyd, unaware ofKomárek's work, also reviewed the species ofNeochloris and distributed them among three genera—Neochloris, Chlorococcopsis gen. nov., andParietochloris gen. nov.—on the basis of details of the covering of the zoospore and the arrangement of the basal bodies of the flagellar apparatus. This paper reconciles these two treatments and makes additional recommendations at the ranks of genus, family, order, and class.     

Phylogeny of cardinalfishes (Teleostei: Gobiiformes: Apogonidae) and the evolution of visceral bioluminescence

The cardinalfishes (Apogonidae) are a diverse clade of small, mostly reef-dwelling fishes, for which a variety of morphological data have not yielded a consistent phylogeny. We use DNA sequence to hypothesize phylogenetic relationships within Apogonidae and among apogonids and other acanthomorph families, to examine patterns of evolution including the distribution of a visceral bioluminescence system. In conformance with previous studies, Apogonidae is placed in a clade with Pempheridae, Kurtidae, Leiognathidae, and Gobioidei. The apogonid genus Pseudamia is recovered outside the remainder of the family, not as sister to the superficially similar genus Gymnapogon. Species sampled from the Caribbean and Western Atlantic (Phaeoptyx, Astrapogon, and some Apogon species) form a clade, as do the larger-bodied Glossamia and Cheilodipterus. Incidence of visceral bioluminescence is found scattered throughout the phylogeny, independently for each group in which it is present. Examination of the fine structure of the visceral bioluminescence system through histology shows that light organs exhibit a range of morphologies, with some composed of complex masses of tubules (Siphamia, Pempheris, Parapriacanthus) and others lacking tubules but containing chambers formed by folds of the visceral epithelium (Acropoma, Archamia, Jaydia, and Rhabdamia). Light organs in Siphamia, Acropoma, Pempheris and Parapriacanthus are distinct from but connected to the gut; those in Archamia, Jaydia, and Rhabdamia are simply portions of the intestinal tract, and are little differentiated from the surrounding tissues. The presence or absence of symbiotic luminescent bacteria does not correlate with light organ structure; the tubular light organs of Siphamia and chambered tubes of Acropoma house bacteria, those in Pempheridae and the other Apogonidae do not.     

Host plants of someRhinanthoideae (Scrophulariaceae) of eastern North America

Twenty three species in 11 genera were examined in the field to determine hosts. OnlyStriga asiatica andSeymeria cassioides have a narrow host range being restricted to grasses and pines, respectively. These are the only species which cause pronounced and sometimes serious host damage. The other species attach to a great diversity of hosts.     

Apoptotic Regulation of Caspase Activity

Intracellular cysteine aspartate-specific proteases (caspases) play both signaling and effector roles in realizing the program of cell death. Caspases function as proteolytic cascades unique for each cell type and signal triggering apoptosis. All parts of the proteolytic cascades are duplicated and controlled by feedback signals. Amplification cycles between pairs of caspases (the third and the sixth, the ninth and the third, the twelfth and the sixth, and others) help multiply the initial apoptotic signal. The presence of physiological inhibitors of apoptosis that directly interact with caspases creates a multilevel regulatory network of apoptosis in cell. The caspase proteolytic cascades are also regulated by sphingolipid secondary messengers, among them ceramide, sphingosine, and their phosphates. Moreover, an association of the caspase signaling with ubiquitin-dependent proteolysis is shown in cells. In particular, the use of extracellular activators and inhibitors of caspases allows irreversible activation of apoptosis in tumor cells or the prevention of apoptosis in cortical neurons under neurodegenerative diseases.     

A molecular phylogeny of Hebeloma species from Europe

In order to widen the scope of existing phylogenies of the ectomycorrhizal agaric genus Hebeloma a total of 53 new rDNA ITS sequences from that genus was generated, augmented by sequences retrieved from GenBank, and analysed using Bayesian, strict consensus and neighbour joining methods. The lignicolous Hebelomina neerlandica, Gymnopilus penetrans, and two species of Galerina served as outgroup taxa. Anamika indica, as well as representatives of the genera Hymenogaster and Naucoria, were included to test the monophyly of Hebeloma, which is confirmed by the results. Hebeloma, Naucoria, Hymenogaster and Anamika indica cluster in a strongly supported monophyletic hebelomatoid clade. All trees largely reflect the current infrageneric classification within Hebeloma, and divide the genus into mostly well-supported monophyletic groups surrounding H. crustuliniforme, H. velutipes, H. sacchariolens, H. sinapizans, and H. radicosum, with H. sarcophyllum being shown at an independent position; however this is not well supported. The section Indusiata divides with strong support into three groups, the position of the pleurocystidiate Hebeloma cistophilum suggests the possible existence of a third subsection within sect. Indusiata. Subsection Sacchariolentia is raised to the rank of section.     

Analysis of twin of eyeless regulation during early embryogenesis in Drosophila melanogaster

The Drosophila Pax6 homolog twin of eyeless (toy) is so far the first zygotically expressed gene involved in eye morphogenesis in Drosophila. The study of its expression during embryogenesis is therefore informative of the initial events of eye development in Drosophila. We have analyzed how the initial expression domain of toy at cellular blastoderm is regulated. We show that the three maternal patterning systems active in the cephalic region (the anterior, terminal and dorsal-ventral systems) cooperate with zygotically activated gap genes to shape the initial expression domain of toy. Whereas Bicoid, Dorsal and Torso signaling synergistically act as activators, Hunchback, Knirps and Decapentaplegic act as repressors.     

New species of Peruvian Orchidaceae III

Sixteen new species are proposed in the generaAckermania, Dressleria, Epidendrum, Maxillaria, Oncidium, Rodriguezia, Sigmatostalix, andTrigonidium. All new species are illustrated.Maxillaria vittariifolia L. O. Williams is newly recorded for Peru. A key is provided forTrigonidium of Peru.Trigonidium loretoense Schltr. andT. peruvianum Schltr. are lectotypified.     

Interaction of Synthetic Analogues of Natural Chalcones and Flavones with Guanidine

The reaction of chalcones and flavones with guanidine in ethanol results in 2-(2-aminopyrimidinyl-4)-phenols.