Interaction of Two Populations of the Blue-Green Algae in Co-Culture

Interaction of the populations of two species of blue-green algae Tolypothrix tenuis and Anabaena variabilis "1058", in mixed culture, was observed in three different ways: (1) The growth competition was studied in mixed-culture, where the two species grew in one batch of culture. (2) The effect of the filtrate, the extracellular products, from the culture of one species on the growth of the other species was studied. (3) In fitrated culture, two algal species were cultivated separately in either side a U-form container partitioned by a micro-pore membrane in the middle. The extracellular products were permeable through the membrane from one side to the other side. The influonce of the biologically active substances prosduced by the algae at different growth stages can be observed and estimated. The growth was measured by dry weight of biomass andchlorophyll-a content. The proportion of components of phycobiliprotein (e. g. ratio of phycocyanin to phycoerythrin) was estimated as the specific growth rate of two blue-greens in the mixed cultures. 1. The results obtained are summarized as follows. There were three types of the bioactivity of the extracellular products: (1) The lethal effects on each other caused the by the lethal agents of these two blue-greens were different. (2) The suppressive effects on growth by each other in one community were also found. (3) Effect on growth promotion exhibited only in the extracellular products of A. variabilis "1058". 2. The results indicate that there occur a direct competitive interaction of two populations. This Competition was controlled by the bio-active substances of the extracellular products which might regulate the structural composition and inturn, the succession of the comunity.     

Separation and partial characterization of two deoxyribonucleic acid polymerases from Spiroplasma citri.

The separation and partial characterization of two deoxyribonucleic acid polymerases from Spiroplasma citri have been achieved. The two enzymes had different elution properties on diethylaminoethyl (DEAE) cellulose and differed in their sensitivity to N-ethylmaleimide (NEM), preference for different template-primers, and sedimentation velocity in linear glycerol gradients. The first enzyme activity, ScA, was retained on DEAE-cellulose and was not inhibited by NEM. Activated deoxyribonucleic acid and poly(dA)-oligo(dT12) were the preferred template-primers. Arabinosyl-cytidine triphosphate had no effect. The sedimentation coefficient of ScA was 6.3s. The second activity, ScB, was not retained on DEAE-cellulose and was inhibited by NEM. Poly(dA)-oligo(dT12) was the preferred template-primer, whereas activated DNA was only poorly utilized. ScB was not affected by arabinosyl-cytidine triphosphate, and its sedimentation coefficient was 4.4s. The polymerization activities of the two enzymes were maximum at 37 to 40 degrees C.     

The organization of two rRNA (rrn) operons of the slow-growing pathogen Mycobacterium celatum provides key insights into mycobacterial evolution

The slow-growing Mycobacterium celatum is known to have two different 16S rRNA gene sequences. This study confirms the presence of two rrn operons and describes their organization. One operon (rrnA) was found to be located downstream from murA and the other (rrnB) was found downstream from tyrS. The promoter regions were sequenced, and also the intergenic transcribed spacer (ITS1 and ITS2) regions separating the 16S rRNA, 23S rRNA and 5S rRNA gene coding regions. Analysis of the RNA fraction revealed that rrnA is regulated by two (P1 and PCL1) promoters and rrnB is regulated by one (P1). These data show that the two rrn operons of M. celatum are organized in the same way as the two rrn operons of classical fast-growing mycobacteria. This information was incorporated into a phylogenetic analysis of the genus based on both 16S rRNA gene sequences and (where possible) the number of rrn operons per genome. The results suggest that the ancestral Mycobacterium possessed two (rrnA and rrnB) operons per genome and that subsequently, on two separate occasions, an operon (rrnB) was lost, leading to two clusters of species having a single operon (rrnA); one cluster includes the classical pathogens and the other includes Mycobacterium abscessus and Mycobacterium chelonae.     

Structure of a highly phosphorylated O-polysaccharide of Proteus mirabilis O41

A highly phosphorylated O-polysaccharide was obtained by mild acid degradation of the lipopolysaccharide of Proteus mirabilis O41 followed by GPC. The initial and dephosphorylated polysaccharides and phosphorylated products from two sequential Smith degradations were studied by (1)H, (13)C and (31)P NMR spectroscopy and ESI-MS. The O-polysaccharide was found to have a tetrasaccharide repeating unit containing one ribitol phosphate (presumably d-Rib-ol-5-P) and two ethanolamine phosphate (Etn-P) groups, one of which is present in the stoichiometric amount and the other in a nonstoichiometric amount. The following structure of the O-polysaccharide was established:     

Purification of recombinant human growth hormone by isoelectric focusing in a multicompartment electrolyzer with Immobiline membranes.

Recombinant human growth hormone (r-hGH) expressed in Escherichia coli, was 70-80% purified by a combination of ion-exchange chromatography and metal ion affinity chromatography. For the last purification step, a multicompartment electrolyzer was used, containing three compartments delimited by isoelectric membranes and two additional anodic and cathodic chambers. The central compartment was situated between two membranes having isoelectric points (pI) of 5.08 (anodic) and of 5.16 (cathodic), i.e. equidistant from the pI value of hGH (pI 5.12). r-hGH was isoelectric between these two membranes and could not leave the central chamber, while more acidic and more cathodic impurities collected in the two lateral chambers under the influence of the electric field. The r-hGH, thus purified, exhibited a single band by isoelectric focusing (IEF) in immobilized pH gradients (IPG) and gave recoveries greater than 90%. The problem of isoelectric precipitation in a practically ion-free environment was alleviated by focusing in 30% glycerol added with 1% neutral detergent (Nonidet-P40). The latter was eliminated by passage through a Q-Sepharose column after collecting the pI 5.12 band from the electrolyzer. Also the pre-hormone (pre-hGH) can be purified in a similar manner (30% glycerol, 1% Nonidet P-40) between two membranes having pIs 4.77 (anodic) and 4.87 (cathodic) (pre-hGH pI 4.82). This paper demonstrates the possibility of purifying by a focusing process also poorly soluble proteins at the pI.     

Structural studies on the active site of Escherichia coli RNA polymerase. 1. Interaction of metals on the i and i + 1 sites

The two substrates between which an internucleotide bond is formed in RNA synthesis occupy two subsites, i and i + 1, on the active site of Escherichia coli RNA polymerase, and each subsite is associated with a metal ion. These ions are therefore useful as probes of substrate interaction during RNA synthesis. We have studied interactions between the metals by EPR spectroscopy. The Zn(II) in the i site and the Mg(II) in the i + 1 site were substituted separately or jointly by Mn(II). The proximity of the metals was established by EPR monitoring of the titration at 5.5 K of the enzyme containing Mn(II) in i with Mn(II) going into the i + 1 site, and the 1:1 ratio of the metals in the two sites was confirmed in this way. The distance between the two metals was determined by EPR titration at room temperature of both the enzyme containing Zn(II) in i and Mn(II) in i with Mn(II) going into the i + 1 site, making use of the fact that EPR spectra are affected by dipolar interactions between the metals. The distances calculated in the presence of enzyme alone, in the presence of enzyme and two ATP substrates, and when poly(dAdT).poly(dAdT) was added to the latter system ranged from 5.2 to 6.7 A.     

Rotenone calibration of fish density and biomass in a tropical stream sampled by two removal methods

A catch-depletion method was applied using two sampling gears in three sites of a small tributary of the Corumba River (Goiás State, Brazil) in two seasons. The gears were: a double stick net (DSN) in one site and electric fishing (EF) in two sites. The calibration of both gears was performed using rotenone. EF was almost sufficient to establish a complete local species list, but DSN was not. Underestimation of calculated density (N) and biomass (B) values for DSN and EF amounted to 62 and 29%, respectively. The results of N and B obtained by EF were too imprecise to calculate secondary fish production to be applied in a field bioenergetics model. We could not conclusively prove that mean body weight of sampled populations was significantly lower for fish caught by EF, although all of these means were higher for fish collected by rotenone, at each site and on two sampling occasions.     

Amino acid sequence of a cyanogen bromide fragment containing the two tryptophanyl residues of lobster arginine kinase (Homarus vulgaris).

Lobster arginine kinase [EC 2.7.3.3] contains 2 tryptophanyl residues and 9 methionyl residues. The whole carboxymethylated protein was first subjected to CNBr cleavage and the resulting fragments were isolated by gel filtration and other experimental approaches. One fragment, CB5, which contains 60 residues including the two tryptophanyl residues and two of the five cysteinyl residues of the protein, was characterized and the results are reported inthis paper. The overall strategy for the establishment of the complete sequence of this fragment was based on the use of three types of peptides: (a) whole cyanogen bromide peptide CB5 which was partially characterized by automatic Edman degradation using a sequencer: 42 steps were performed out of 60 residues, (b) tryptic peptides of CB5, (c) peptides formed by cleavage of S-carboxymethylated arginine kinase (whole protein) at the two tryptophanyl residues with BNPS-skatole. The complete amino acid sequence of the CNBr polypeptide (CB5) which contains the two tryptophanyl residues of the whole protein was established.     

核酸疫苗双表达载体的构建及表达

将微小病毒内部核糖体进入位点(IRES)基因克隆到质粒pVAXI载体多克隆位点,构建出核酸疫苗双表达载体pVI。将绿色荧光蛋白(EGFP)基因和新霉素磷酸转移酶(neor)基因作为报告基因,连接到pVI载体IRES基因的前后两处多克隆位点,构建出表达载体pEIN。通过脂质体介导的方法将该载体转染COS-7细胞,筛选到同时表达绿色荧光蛋白和新霉素磷酸转移酶的表达株,表明成功地构建了核酸疫苗双表达载体,为构建多价核酸疫苗及带有分子佐剂的核酸疫苗打下了基础。     

A preliminary investigation on genetic diversity of Sousa chinensis in the Pearl River Estuary and Xiamen of Chinese waters

In this study, the mitochondrial DNA (mtDNA) control region and the mitochondrial cytochrome b gene of stranded Indo-Pacific humpback dolphin (Sousa chinensis) samples from the Pearl River Estuary and Xiamen waters were sequenced and analyzed. The result of mtDNA control region revealed 34 variable sites and four unique haplotypes (named as A, B, C and D) identified among the total samples from these two water areas, and the most common haplotype (A) was shared by 75% of the dolphins sampled from the two water areas. The haplotypic diversity (h) was 0.455 and the nucleotide diversity (π) was 0.0088. The phylogenetic analysis showed that the haplotype A, C, and D were closely related, but the haplotype B (unique for XM01 from Xiamen) was far from the other three. By scanning cytochrome b fragments, two haplotypes (A and B) were identified in these two water areas, and the most common haplotype (A) was shared by 91.67% individuals, while XM01 from Xiamen as the only exception. The date suggest that there is a possibility of gene exchange between the two populations in the Pearl River Estuary and Xiamen waters, and there possibly exists a unique maternal lineage in Xiamen waters.     

Subunit constitution of carbonic anhydrase from Chlamydomonas reinhardtii

Carbonic anhydrase purified from the cell surface of Chlamydomonas reinhardtii was inactivated by treatment with dithiothreitol. This treatment caused dissociation of the holoenzyme into 35-kDa (A) and 4-kDa (B) subunits as revealed by SDS/PAGE. The 35-kDa subunit was further separated into two components A1 (35 kDa) and A2 (36.5 kDa) by SDS/PAGE using a gradient gel. These two components have the same amino acid sequence up to at least the 10th amino acid from the N-terminus. The molecular masses were estimated at 76 kDa and 35 kDa for the holoenzyme and the large subunit, respectively, and the molar ratio of the former to the latter at 1:2, by using the techniques of low-angle laser light-scattering photometry and precision differential refractometry combined with gel-filtration HPLC. The molar ratio of the 35-kDa/4-kDa subunits was estimated at 1:1 the gel-filtration HPLC monitored with precision differential refractometry. Atomic-absorption spectrophotometry revealed that the holoenzyme contains two atoms of zinc. These results suggest that the holoenzyme is a heterotetramer composed of two large subunits (A1 and A2) and two small subunits (B).     

Analysis of the progesterone displacement of its human serum albumin binding site by beta-estradiol using biochromatographic approaches: effect of two salt modifiers

The mechanisms of (i) the binding of two sex-hormones (i.e. progesterone and beta-estradiol) to human serum albumin (HSA) and (ii) the progesterone displacement of its HSA binding cavity by beta-estradiol were studied by biochromatography using three different methods. In the first time, zonal elution method was used to prove the direct competition effect between the two sex-hormone. In the second time, the competition effect between beta-estradiol and progesterone to bound on the same HSA site was analysed by the competitive bi-Langmuir approach. Finally, the thermodynamic data of these two binding processes were studied. The Gibbs free energy value (Delta(approximately)G degrees) of the displacement equilibrium was negative demonstrating that beta-estradiol displaced progesterone of its HSA binding cavity. Moreover, the effect of two chloride modifiers (i.e. Na(+), Mg(2+)) on these two binding processes were analysed. Results showed that in the salt biological concentration ranges, the Mg(2+) cation enhanced strongly the bioavailable progesterone, whereas the Na(+) cation interacted slowly on the progesterone displacement of its HSA binding site by beta-estradiol. This study showed that it must be useful to carry out more in vivo test on the magnesium supplementation effect for women who suffer from estrogen dominance syndrome.     

水稻蜡质基因引导区的两个SSR序列与直链淀粉含量的相关性(英文)

分析了蜡质基因引导区的两个简单重复序列 (SSR) (CT) n 和 (AATT) n 在 74份水稻材料中的多态性及其与直链淀粉含量 (AC)的关系。这些材料包括了籼稻 (OryzasativaL .ssp .indica)、粳稻 (O .sativassp .japonica)和普通野生稻 (O .rufipogon) ,其AC值覆盖了栽培稻AC分布的整个范围。以 (CT) n 作标记检测到 8个等位基因 ,粳稻品种趋于含有重复数目较多 (n≥ 16 )的等位基因 ,重复次数较少 (n≤ 14)的等位基因只出现在籼稻中。 (AATT)n检测到 2个等位基因 ,野生稻中少数植株表现出杂合性。分析表明AC与这两个SSR序列基因型高度相关 ,高AC (>2 2 .0 % )品种具有 (CT)重复次数较少 (n≤ 14)的等位基因 ;相反 ,除了糯米外 ,所有低或者中等AC的品种都有 (CT)重复数较多 (n≥ 16 )的等位基因。具有重复次数较多的 (AATT) 6等位基因的品种多为高AC ,具有重复次数较少的(AATT) 5等位基因的品种多为低或中等AC。不同SSR基因型品种间AC差异极显著。虽然目前还不能确定这两个SSR序列在直链淀粉合成中的直接功能 ,SSR变异与AC间近乎完全的相关性可作为分子标记直接用于水稻的品质改良。     

Chemical Characterization of Lodoicea maldivica Fruit

In the present study, we report the attempt to characterize the chemical composition of fruit kernel of Lodoicea maldivica coco nucifera palm (commonly named as ‘Coco de mer’) by gas chromatographic method. The analysis was performed by HS‐SPME and GC/MS techniques to determine volatile aroma, sterol, and fatty acid composition profiles in the internal and external pulp of two distinct coconuts. Although no qualitative differences in flavour composition were observed between the two analysed coconuts and the relative two pulp parts, variations in the abundance levels of the prominent compounds have been recorded. The averaged quantity of total phytosterols, resulting from the two analysed ‘Coco de mer’ samples, was almost constant in both kernels coconut, being 24.5 μg/g (of dry net matter) for the external, and 26.9 μg/g (of dry net matter) for the internal portion. In both coconuts, the fatty acid pattern composition was characterized by seven saturated acids ranged from C14:0 (myristic) to C20:0 (arachidic) and two monounsaturated acids, the palmitoleic (C16:1, ω7) and the oleic (C18:1, ω9). Palmitic acid (C16:0) was the predominant one with an average contribution of about 49.0%, followed by pentadecanoic 16.5%, stearic (C18:0) 11.6%, and myristic (C14:0) 9.9% acids in all two examined kernel portions.     

Cooperative catalysis in the homodimer subunits of xanthine oxidase

Xanthine oxidase (XOD) consists of two identical subunits. For the past 50 years or so, it was assumed that the two subunits carry out catalysis independently. Herein, we report that the presence of 6-formylpterin (6FP) or other substrates (such as xanthine or xanthopterin) at one of the two active sites affects the binding affinity and catalysis rate of 6FP at the other. When the two XOD active sites were occupied by two 6FPs simultaneously, the conversion rate (2.8 x 10(-3) s(-1)) of 6FP to 6CP is 2.95-fold faster than the conversion rate (0.95 x 10(-3) s(-1)) in the case of single 6FP bound condition. The presence of xanthine can accelerate the catalysis rate of 6FP by XOD as well as the activity-recovering rate of alloxanthine-inhibited XOD. Our experimental observations demonstrate unambiguously that the two XOD subunits are strongly cooperative in both binding and catalysis. The inhibition constant (Ki) of 6FP toward XOD was measured by a stopped-flow method to be 0.94 nM.     

beta-Glucosidase of Penicillium funiculosum. II. Properties and mycelial binding

The properties of two isozymes of beta-glucosidase of Penicillium funiculosum (part I of this series) are described. The molecular weights of isozyme 1 was 2.3 x 10(5) by gel filtration and 1.2 x 10(5) by SDS gel electrophoresis, indicating two subunits. The molecular weight of isozyme 2 was unusually low for a fungal beta-glucosidase: 1.6 x 10(4) by gel filtration and 3.7 x 10(4) in the presence of isopropanol. The two enzymes differed from other fungal beta-glucosidases in their substrate specificities. They showed high activity with pNPG, cellobiose, cellotriose, cellotetraose, cellopentaose, gentiobiose, and laminarin, but were inactive with filter paper, CM cellulose, or derivatives or stabilized by bovine serum albumin and several alcohols such as butanol and propanol. It was inhibited by glucono-delta-lactone (K(i) = 0.67muM) and glucose (K(i) = 0.92mM).The enzyme was quantitatively adsorbed by P. funiculosum mycelium at pH 4 and the immobilized enzyme was as enzymically active as the free enzyme, but more heat stable. The binding efficiency was very high (5000 IU enzyme/g mycelium). It could be quantitatively eluted with buffers at pH 7 or by 0.02M Ca, Mg, or Al chlorides. The binding was selective, since mycelium grown on lactose could produce and also bind only beta-glucosidase isozyme 1, whereas mycelium grown on cellulose could produce as well as bind both beta-glucosidase isozymes as well as cellulases. Mycelial binding was unaffected by washing with EDTA or trypsinization, but was totally lost by washing with dilute KOH, HCl, or ethylenediamine.     

Identification of two variants of troponin T in the developing chicken heart using a monoclonal antibody

Troponin T (TNT) expressed in the developing chicken cardiac muscle was examined by immunoblotting combined with two-dimensional electrophoresis (2-D PAGE) and peptide mapping. When the whole lysate of the neonatal heart was examined by 2-D PAGE, two TNT variants were detected on the gel by monoclonal antibody to TNT. Expression of the two variants was developmentally regulated: one isoform (type I) was expressed from embryonic through neonatal stages, and the other (type II) from the late embryonic stage through adulthood during cardiac muscle development. The type-I isoform, but not type-II isoform, was also expressed transiently in chicken skeletal muscle at embryonic stages. As judged from the peptide maps, the two isoforms differed in the N-terminal region but not in the C-terminal region.     

Functional response of two aphidophagous ladybirds searching in tandem

The functional response of two ladybird species, Propylea dissecta (Mulsant) and Coccinella transversalis Fabricius in combination was studied in an effort to determine the impact of two predators on the increasing density of aphid, Aphis gossypii Glover infesting leaves of bottle gourd, Lagenaria vulgaris Seringe. The ladybirds were exposed to prey density in three combinations using adult females: (i) one P. dissecta and one C. transversalis together, (ii) two P. dissecta, and (iii) two C. transversalis, for 24 h. Prey consumption increased curvilinearly with prey density in all three combinations. It was maximum when heterospecifics searched together. The prey were handled and consumed significantly faster (9.51 min) by heterospecifics in combination, followed by two C. transversalis (11.32 min) and two P. dissecta (12.52 min). The attack rate was maximum (0.00274) by heterospecifics followed by the two C. transversalis (0.00166) and two P. dissecta (0.00092). The synergistic effect on the prey consumption may possibly be due to spatial distribution of P. dissecta and C. transversalis in terms of feeding sites, with the former being negatively, and the latter being positively geotactic. Field release of two predator species in tandem is recommended for biocontrol of A. gossypii because of the potential for synergistic action by these natural enemies.     

Characterization of soluble and membrane-bound family 3 lytic transglycosylases from Pseudomonas aeruginosa.

Lytic transglycosylases cleave the beta,1-->4 glycosidic linkages between the N-acetylmuramoyl (MurNAc) and N-acetylglucosaminyl (GlcNAc) residues of peptidoglycan with the concomitant formation of 1,6-anhydro-N-acetylmuramyl reaction products. The genes encoding two hypothetical lytic transglycosylases were identified in the genome of Pseudomonas aeruginosa PAO1 by a BLAST search using membrane-bound lytic transglycosylase B (MltB) from Escherichia coli as the query. The two genes were amplified by PCR and cloned as fusion proteins with C-terminal hexa-His sequences. Expression studies of the two genes in E. coli in the presence of [(3)H]palmitate resulted in the labeling of only one of the two enzymes. This enzyme, named MltB, was overexpressed to form insoluble inclusion bodies. Its gene was engineered to produce a truncated form of the enzyme lacking its N-terminal 17 residues which includes Cys17, the putative site of lipidation. This MltB derivative (named sMltB) was shown to not label with [(3)H]palmitate, and it was overexpressed in soluble form. The second, nonlabeled enzyme was overexpressed in soluble form and hence was named soluble lytic transglycosylase B (SltB). Both sMltB and SltB were purified to apparent homogeneity by a combination of affinity (Ni(2+)-NTA), cation-exchange (Mono S), and gel permeation (Superdex 75) chromatographies. The reaction products released by the two enzymes from purified, insoluble peptidoglycan were characterized by a novel high-performance anion-exchange chromatography (HPAEC) assay. Both enzymes produced the same three major soluble products which were identified as anhydromuropeptides based on ESI-MS analysis (cross-linked anhydrodisaccharide-tetrasaccharide, m/z obs 1824.9; anhydrodisaccharide-pentapeptide, m/z obs 922.2; and anhydrodisaccharide-tripeptide, m/z obs 851.3. The Michaelis-Menten kinetic parameters were also determined for the two enzymes using the same insoluble peptidoglycan substrate by aminosugar compositional analysis of soluble reaction products. At pH 5.8 and in the presence of 0.1% Triton, SltB was found to be more catalytically efficient, as reflected by its k(cat)/K(M) value, than sMltB.