Differentiation of isomeric Lewis blood groups by positive ion electrospray tandem mass spectrometry

Lewis histo-blood group antigens are one of the major classes of biologically active oligosaccharides. In this work, underivatized Lewis blood groups were studied by electrospray tandem mass spectrometry (ESI-MSⁿ) in the positive mode with three different mass analyzers: Q-TOF (quadrupole time-of-flight), QqQ (triple quadrupole), and LIT (linear ion trap). It was observed that, under collision-induced fragmentations, type 1 Lewis antigens (Le^a and Le^b) could be distinguished from type 2 (Le^x and Le^y) on the basis of specific fragmentations of the GlcNAc unit. Whereas O-4-linked sugars of the GlcNAc are lost as residues, the O-3-linked sugars undergo fragmentation both as sugar units and as sugar residues (unit −18 Da). Type 2 Lewis antigens also showed a characteristic cross-ring cleavage ^0,2A₂ of the GlcNAc. As a result, the product ions at m/z 388 and 305, characteristic of Le^x, and m/z 372, characteristic of Le^a, are proposed to distinguish the trisaccharide isomers Le^x/Le^a. Also, the product ions at m/z 534 and 305, characteristic of Le^y, and m/z 372, characteristic of Le^b, are proposed to distinguish the tetrasaccharide isomers Le^b/Le^y. These diagnostic fragment ions were further applied in the identification of Lewis type 2 antigens (Le^x and Le^y) in the lipopolysaccharide of the human gastric pathogen, Helicobacter pylori.     

10. Na Bahně (Czech Republic): Vegetation development over the last 2.5 millennia in the Eastern Bohemian lowland

To determine the best date for patients in the southern part of the Netherlands to begin treatment for pollinosis, an attempt was made to predict the start of the grass pollen season at Helmond as accurately as possible, as was previously done at Leiden. The start of the grass pollen season was defined as the date when at a given location the accumulated total (from 1 Jan.) of 24 h average grass pollen concentrations (No./m³) reaches 100 (the so-called Σ100-method). Using the phenological method over the years 1981 through 1985, with the birch (Σ125=x) as the indicator plant, the start of the grass pollen period (Σ100=z) could be predicted much more accurately than would have been possible solely on the basis of the mean starting dates in the preceding years. The predicted starting date (z) can be calculated with the equation z=0.44x+95.46 (x and z as day-of-year numbers), SD=3.6 days, r=0.83, n=5). The SD of the Σ100-method of grasses being 5.6 days, the effectivity of the prediction is 35.7%. The difference in results between Helmond and Leiden is discussed.     

A Note on the Estimation of the Population Mean in Stratified Random Sampling Using Two Auxiliary Variables

In this paper, a two‐phase sampling estimator for a stratified population mean using two auxiliary variables x and z is considered when the stratum mean of x is unknown but that of z is known. The suggested estimator under its optimal condition is found to be more efficient than the one using only x.     

The qualitative analysis of a difference equation of population growth

The difference equation f _b :[0,1]–[0,1] defined by f _b (x)=b x(1–x) is studied. In particular complete qualitative information is obtained for the parameter value b=3.83. For example the number of fixed points of (f _b )ⁱ is given by

Efficient estimation of temperature distribution, heat storage, thermocline migration and vertical eddy conductivities in stratified lakes

1. Factorial designs were used to investigate the spatial and temporal components of temperature sampling error in two medium-sized (maximum fetch = 9 and 11 km; maximum depth = 24 and 70m) Wisconsin lakes (Mendota and Green). Sampling designs were then optimized for estimating temperature distributions, thermocline migration, lake heat content, and vertical eddy conductivities in these and similar stratified lakes. 2. Errors were at a minimum for: (i) isotherms positioned ¹/₃ - ¹/₂ of the way down through the seasonal thermocline; (ii) at lake stations located near the node of the principal internal seiche; (iii) after an extended interval of low windpower. If seven spatially distributed lake stations were sampled n₁, n₂ times during the two low-power intervals bracketing a weather front, and the rime delay between revisits was randomized with respect to the period of the uninodal temperature seiches, the resulting standard error (cm) in ΔZ?₁₇ (depth of 17° isotherm; an unbiased, minimum-variance estimator for main thermocline migration) was (144/n₁+ 144/n₂)^1/2. If n₁=n₂= 2 ‘revisits’, the resulting CV (coefficient of variation) was 5–10% for ΔZ?₁₇ accompanying major individual cold fronts in early summer. 3. When estimating K_z, the vertical eddy conductivity, the most important component of error relates to ΔH_z, the change in heat content below depth z. The error in ΔH_z is minimized in the same manner as for lake-mean isotherm depth. Using the Mendota sampling design described above, the RMS error in ΔH_z decreases from ～90 cal cm^?2 in the upper metalimnion to ～35calcm^?2 near the base of the metalimnion. For seven take stations, and n₁= n₂= 2, K_z can be estimated with a CV ～10% bracketing a single major cold front. The CV decreases approximately as ΔH_z^?1, hence is roughly proportional to Δt^?1 or to (cumuiative windpower)^?1.     

Calibration of FST-hemispheres against bottom shear stress in a laboratory flume*

SUMMARY.

• 1 Fliesswasserstammtisch (FST)-hemispheres of identical size but different densities were exposed on a horizontal plane on the pebble-covered bottom of a laboratory flume at streaming to shooting, turbulent and fully developed flow. The heaviest hemisphere moved was used as an indicator of shear stress, a flow force acting on the flume bottom.
• 2 The relationship between shear stress and hemisphere density was practically the same for three different sets of hemispheres, namely one prototype set newly prepared for the calibrations, one prototype set intensively used in the field prior to calibrations, and one randomly selected new set bought commercially.
• 3 Shear stress (y, dyn cm^?2) was related to hemisphere density (x, g cm^?3) by y= x^2.85 (n= 69; r²= 0.993). For lighter hemispheres this relationship was better explained by the linear model y= 7.32x– 6.60 (n= 35; r²=0.983).

     

How geometration reduces the velocity of DNA in gel electrophoresis

Summary New correction is derived to the velocity of geometrating molecules in gel. The formalism takes into account the random character of the gel medium. The correction comes from the possibility of two simultaneous hookings of a molecule at gel fibres. The calculated velocity is shown to be inversely proportional to 1+3x/4+x ²/3, where x=s/b, s is the molecule length and b is a mean free path. This result shows that the velocity of DNA decreases with the molecule length sharper, than it was previously estimated.     

Optimal control strategy for the enhanced production of cellulase enzyme using the new mutant Trichoderma reesei E-12

Cellulase enzyme production was enhanced using the mutant strain Trichoderma reesei, E-12, which was shown to be partially resistant to catabolite repression. An optimal profile for pH, which was found to be the critical environmental parameter, was determined using a rigorous mathematical optimization procedure. Semi-empirical models were used to minimize complications in the computation. A 30% increase in enzyme activity and productivity was obtained using the optimal pH strategy as compared to the pH cycling strategy.List of Symbols a ₁ , a ₂ , a ₃ d^–1, d^–2, d^–3 coefficients of the polynomial in the generalized logistic growth model - a ₄, a ₅, a ₆ d^–1, d^–2, d^–3 coefficients of the polynomial in the generalized logistic product model - b ₁ d^–1 enzyme synthesis rate constant - b ₂ d ^–1 enzyme decay rate constant - b ₃ power coefficient in the polynomial model for enzyme synthesis - H Hamiltonian function - J Objective function of the maximization procedure - K ₁ kg/m³ limiting cell mass concentration in biomass logistic model - K _s kg/m³ saturation constant - K ^s kg/m³ saturation death rate constant - q power coefficient in polynomial model - s kg/m³ substrate concentration - t d fermentation time - T d total fermentation time (=7 d) - x ₁₀ kg/m³ initial biomass concentration - x ₁ kg/m³ biomass concentration at time t - x ₂ F.P.A enzyme activity at time t - x ₃ d state variable replacing time term on the right hand side of biomass equation - x _f kg/m³ final biomass concentration - z ₁, z ₂, z ₃ adjoint variable corresponding to state variable x ₁, x ₂, x ₃ - d^–1 specific death rate - d^–1 specific growth rate     

Carbohydrate phenotyping of human and animal milk glycoproteins

Breast-milk has a well-known anti-microbial effect, which is in part due to the many different carbohydrate structures expressed. This renders it a position as a potential therapeutic for treatment of infection by different pathogens, thus avoiding the drawbacks of many antibiotics. The plethora of carbohydrate epitopes in breast-milk is known to differ between species, with human milk expressing the most complex one. We have investigated the expression of protein-bound carbohydrate epitopes in milk from man, cow, goat, sheep, pig, horse, dromedary and rabbit. Proteins were separated by SDS-PAGE and the presence of carbohydrate epitopes on milk proteins were analysed by Western blotting using different lectins and carbohydrate-specific antibodies. We show that ABH, Lewis (Le)^x, sialyl-Le^x, Le^a, sialyl-Le^a and Le^b carbohydrate epitopes are expressed mainly on man, pig and horse milk proteins. The blood group precursor structure H type 1 is expressed in all species investigated, while only pig, dromedary and rabbit milk proteins carry H type 2 epitopes. These epitopes are receptors for Helicobacter pylori (Le^b and sialyl-Le^x), enteropathogenic (H type 1, Le^a and Le^x) and enterotoxic Escherichia coli (heat-stable toxin; H type 1 and 2), and Campylobacter jejuni (H type 2). Thus, milk from these animals or their genetically modified descendants could have a therapeutic effect by inhibiting pathogen colonization and infection. Published in 2005.     

Cytogenetic characterization and nuclear DNA content of three North African endemic Centaurea species

Three endemic Centaurea species from North Africa are investigated for the first time by chromomycin fluorochrome banding for GC-rich DNA distribution, fluorescence in situ hybridization for physical mapping of rRNA genes, and flow cytometry for genome-size assessment. Investigated species belong to three different sections and possess three basic chromosome numbers: C. tougourensis subsp. tougourensis 2n = 4x = 36 (x = 9), C. musimonum 2n = 2x = 20 (x = 10), and C. maroccana 2n = 2x = 24 (x = 12). The number and distribution of chromomycin positive bands (CMA⁺) and 18S-5.8S-26S (35S) rDNA loci were different among investigated species and ranged from 6 to 80 chromomycin bands and from 2 to 6 35S rDNA loci. The three species have just one 5S rDNA locus at intercalary position on a separate chromosome pairs, except in the case of C. musimonum in which both rDNA loci were localized on the same chromosome. All rDNA loci were co-localized with CMA⁺ bands, except three 35S in C. musimonum. Genome size ranged from 2C = 1.66 to 2C = 2.86 pg in diploid species (C. musimonum and C. maroccana, respectively) and to 2C = 4.51 pg in tetraploid C. tougourensis subsp. tougourensis.     

Sampling strategies for estimating brook trout effective population size

The influence of sampling strategy on estimates of effective population size (N _e ) from single-sample genetic methods has not been rigorously examined, though these methods are increasingly used. For headwater salmonids, spatially close kin association among age-0 individuals suggests that sampling strategy (number of individuals and location from which they are collected) will influence estimates of N _e through family representation effects. We collected age-0 brook trout by completely sampling three headwater habitat patches, and used microsatellite data and empirically parameterized simulations to test the effects of different combinations of sample size (S = 25, 50, 75, 100, 150, or 200) and number of equally-spaced sample starting locations (SL = 1, 2, 3, 4, or random) on estimates of mean family size and effective number of breeders (N _b ). Both S and SL had a strong influence on estimates of mean family size and [^(N)]_b , \hat{N}_{b} , however the strength of the effects varied among habitat patches that varied in family spatial distributions. The sampling strategy that resulted in an optimal balance between precise estimates of N _b and sampling effort regardless of family structure occurred with S = 75 and SL = 3. This strategy limited bias by ensuring samples contained individuals from a high proportion of available families while providing a large enough sample size for precise estimates. Because this sampling effort performed well for populations that vary in family structure, it should provide a generally applicable approach for genetic monitoring of iteroparous headwater stream fishes that have overlapping generations.     

Helicobacter pylori infection can change the intensity of gastric Lewis antigen expressions differently between adults and children

This study tested whether there were different expressions of gastric Lewis antigens between children and adults with Helicobacter pylori infection, and whether the difference was related to the infection outcome. About 68 dyspeptic children and 110 dyspeptic adults were enrolled to check H. pylori infection, its colonization density, and the related histology. Gastric Lewis antigens b (Le^b), x (Le^x), and sialyl-Lewis x (sialyl-Le^x) were immunohistochemically stained and scored for the intensity. The H. pylori-infected adults, but not the children, had a lower Le^b intensity over the antrum (p = 0.019) but higher Le^b intensity over the corpus (p = 0.001) than the non-infected ones. Over the antrum, both the H. pylori-infected children and adults had a lower Le^x and higher sialyl-Le^x intensity than those non-infected ones (p < 0.05). The H. pylori-infected adults had a higher bacterial density (p = 0.004) and Le^b intensity (p = 0.016) over the corpus than the H. pylori-infected children. For the H. pylori-infected adults, but not children, the corpus had a higher Le^b (p = 0.038) and lower Le^x (p = 0.005) intensity than the antrum. Furthermore, the H. pylori-infected adults expressed a higher Le^b and had a higher bacterial density than those with weak Le^b (antrum, p < 0.001; corpus, p = 0.001). In conclusion, H. pylori infection is associated with the intensity change of Lewis antigen expressions in the stomach. The changes of gastric Lewis antigen expressions are different between adults and children with H. pylori infection, which may exert different H. pylori colonization over the corpus between adults and children.     

Length-weight relationship of 74 fish species caught in the continental coast of Ecuador

This work analysis the length-weight relationships for fish species captured by artisanal fishery along the continental coast of Ecuador. Fishermen used the following fishing gear: beach seine nets (5.1–31.8 mm), shrimp trawl nets (21.8–31.8 mm) and bottom gill nets (54.1–203.2 mm). Sampling took place during the years 2012 and 2014. Frequency of sampling was monthly, and it was completed systematically from Southern toward Northern Provinces. Length-weight relationship (LWR) was realized by the power model (y = a × x^b), for species with a bivariate dataset >70. A total of 59 commercial and 15 non-commercial species were registered. For 74 species, our analysis including a higher total length not reported in LWR estimates previously. The determination coefficient (r²) value was always above 0.95.     

Comparison of two methods of reciprocal recurrent selection in maize (Zea mays L.)

Reciprocal recurrent selection (RRS) was proposed for simultaneously improving two populations and their cross. A modification of the classical full-sib RRS (FS-RRS) was proposed in which the performance of full-sibs and S₂ families is combined in a selection index (FS-S₂-RRS). The Mediterranean corn borer (MCB) is the main corn borer species in the Mediterranean and adjacent areas and produces important yield losses. We started two RRS programs (FS-RRS and FS-S₂-RRS) from the same maize population in which the selection criterion was grain yield under artificial infestation with MCB eggs. Original populations, two cycles of selection derived from them by both RRS methods, and population crosses were evaluated under MCB attack and under insecticide treatment in three different environments. The objective was to compare the efficiency of the FS-RRS and the FS-S₂-RRS methods for improving grain yield. We found that the FS-S₂-RRS method was successful for improving the yield of the population cross under optimum conditions (the regression coefficient over cycles was b = 0.87** Mg ha⁻¹ cycle⁻¹) without losing yield under high pressure of MCB attack (b = 0.07). On the contrary, FS-RRS failed to improve the yield of the population cross under optimum conditions (b = 0.65) and tended to decrease the yield under high levels of MCB attack (b = −0.26). We conclude that for developing high yielding and stable varieties, FS-S₂-RRS is more efficient than the classical FS-RRS method.     

Isolation and measurement of urinary 8-iso-prostaglandin F2α by high-performance liquid chromatography and gas chromatography–mass spectrometry

8-iso-Prostaglandin F_2α (8-iso-PGF_2α) is a product of free radical-catalyzed peroxidation of arachidonic acid. Measurement of its urinary excretion has been proposed as an index of oxidative status in vivo. A stable isotope dilution method for its quantification by gas chromatography–electron capture chemical ionization mass spectrometry is described. Sample cleanup required the combined use of high-performance liquid chromatography and thin-layer chromatography. The inter-assay R.S.D. in two separate determinations was 1.6 (n=4) and 2.3% (n=4). The accuracy of the assay was evaluated through recovery experiments. The equation of the regression plot correlating the amounts added and recovered was y=0.91x−0.31, r=0.9916 (n=12). The pair of fragment ions ([M−181]⁻) at m/z 569 and m/z 573 was monitored for quantification. The mean 8-iso-PGF_2α excretion rate was 528±127 (S.D.) ng per day in five male volunteers and 730±305 ng per day in six females. Intake of 80 mg of lycopene per day by eleven volunteers for four weeks resulted in a non-significant reduction of 8-iso-PGF_2α excretion.     

北京山区河岸带植物群落种-面积关系

种-面积关系是群落生态学的基本问题之一,是了解植物群落结构的重要途径。为摸清北京山区河流河岸带植物群落调查最小样方面积,在北京市怀柔区怀九河河岸带沿线,采用基于河岸带立地条件逐步扩大样地面积的方法布设50个80m长样地,调查计算并拟合不同类型河岸带所需的最小样地面积。研究结果表明:北京市怀柔区怀九河河岸带植物种数255种,隶属于70科185属。通过聚类分析将怀九河河岸带分为自然河岸带、近自然河岸带、人工岸坡乔灌草河岸带、人工岸坡观赏性乔灌草河岸带、人工岸坡疏乔灌草干砌石河岸带和人工岸坡浆砌石河岸带6种类型。根据赤池信息量准则AIC可知自然河岸带、近自然河岸带、人工岸坡乔灌草河岸带和人工岸坡疏乔灌草干砌石河岸带优先选取S=c-ae~(-bA),人工岸坡观赏性乔灌草河岸带优先选取S=aA/(1+bA),人工岸坡浆砌石河岸带优先选取S=c/(1+ae~(-bA))。满足相同比例植物种调查,不同类型河岸带所需最小样地面积存在明显差异,当满足河岸带植物调查80%植物种时,人工岸坡浆砌石河岸带(84m~2)和自然河岸带(217m~2)所需样地面积较小,其次是人工岸坡疏乔灌草干砌石河岸带(362m~2),近自然河岸带(450m~2)和人工岸坡乔灌草河岸带(460m~2)所需样地面积相似,而人工岸坡观赏性乔灌草河岸带所需样地面积最大为571m~2。所得出的河岸带植物调查最小样地面积对于河岸带生物多样性保护和指导河岸带生态修复具有重要意义。     

煤矿复垦区土壤水动力学特性对下渗过程的影响

煤矿复垦区土壤水对植物生长、溶质运移以及土壤环境的变化起着至关重要的作用。定量揭示煤矿复垦区土壤水下渗过程是亟待诠释的关键科学问题。本研究通过测定典型矿区不同深度土壤非饱和导水率、容重、总孔隙度和粒径等水动力学参数,结合染色示踪试验,刻画矿区非饱和带土壤水运移过程。染色示踪结果显示30、60 L和90 L这3种实验下渗水量条件下,水流沿X方向侧向扩散的最大距离分别为10、30 cm和35 cm,沿Y方向侧向扩散的最大距离分别为10、25 cm和30 cm。互相关函数显示随着下渗水量增大,水流扩散作用也在加强,但过多水量并没有明显增加下渗深度和扩散距离。吸力大于300 hpa时,0.01—0.05 mm土壤粒径含量和非饱和导水率呈负相关关系;吸力和非饱和导水率采用指数函数拟合效果较好(r~20.9),对拟合参数a、b和土壤容重(x)进行回归分析:a=0.0015x~2-0.00499x+0.0004,b=0.0583x~2+0.1234x-0.072。同一吸力下土壤容重大的土样非饱和导水率较小;吸力值为300 hpa是非饱和导水率的转折点;非饱和导水率和土壤容重呈现负相关关系,和总孔隙度呈现正相关关系,且二者的相关性随吸力的增加而降低。     

Characterisation of high- and low-molecular weight glutenin subunits associated to the D genome of Aegilops tauschii in a collection of synthetic hexaploid wheats

Synthetic hexaploid wheats (2n=6x=42, AABBDD) involving genomes from Triticum turgidum (2n= 4x=28, AABB) and Aegilops tauschii (2n=2x=14, DD) have been produced as a means for introducing desirable characteristics into bread wheat. In the present work we describe the genetic variability present at the Glu-D ^t 1 and Glu-D ^t 3 loci, encoding high- (HMW) and low-molecular-weight (LMW) glutenin subunits respectively, derived from Ae. tauschii, using electrophoretic and chromatographic methods, in a collection of synthetic hexaploid wheats. A wide variation both in mobility and surface hydrophobicity of HMW glutenin subunits was observed between different accessions of Ae. tauschii used in the production of the synthetic hexaploids. A combination of electrophoretic and chromatographic methods improves the identification of HMW glutenin subunits; in fact subunits with identical apparent mobility were revealed to have a different surface hydrophobicity by reversed-phase high performance liquid chromatography. None of the Dx5^t subunits present in Ae. tauschii showed the presence of the extra cysteine residue found in the HMW glutenin subunit Dx5 of Triticum aestivum, as revealed by selective amplification with polymerase chain reaction (PCR). The wide variability and the high number of subunits encoded by the Glu-D ^t 3 locus suggests that Ae. tauschii may be a rich source for enhancing the genetic variability of glutenin subunits in bread wheat and improving bread-making properties. Received: 3 March 2001 / Accepted: 23 March 2001     

Site‐Selective In Situ Electrochemical Doping for Mn‐Rich Layered Oxide Cathode Materials in Lithium‐Ion Batteries

Various doped materials have been investigated to improve the structural stability of layered transition metal oxides for lithium‐ion batteries. Most doped materials are obtained through solid state methods, in which the doping of cations is not strictly site selective. This paper demonstrates, for the first time, an in situ electrochemical site‐selective doping process that selectively substitutes Li⁺ at Li sites in Mn‐rich layered oxides with Mg²⁺. Mg²⁺ cations are electrochemically intercalated into Li sites in delithiated Mn‐rich layered oxides, resulting in the formation of [Li_1?xMg_y][Mn_1?zM_z]O₂ (M = Co and Ni). This Mg²⁺ intercalation is irreversible, leading to the favorable doping of Mg²⁺ at the Li sites. More interestingly, the amount of intercalated Mg²⁺ dopants increases with the increasing amount of Mn in Li_1?x[Mn_1?zM_z]O₂, which is attributed to the fact that the Mn‐to‐O electron transfer enhances the attractive interaction between Mg²⁺ dopants and electronegative O^δ? atoms. Moreover, Mg²⁺ at the Li sites in layered oxides suppresses cation mixing during cycling, resulting in markedly improved capacity retention over 200 cycles. The first‐principle calculations further clarify the role of Mg²⁺ in reduced cation mixing during cycling. The new concept of in situ electrochemical doping provides a new avenue for the development of various selectively doped materials.     

Effects of Botrytis fabae infection and mechanical defoliation on seed yield of field beans (Vicia faba)

Effects on seed yield of mechanical defoliation and inoculation with Botrytis fabae were compared using pot-grown plants of Vicia faba (cv. Maris Beagle). Treatments, which were made at the end of flowering, were applied singly and in all combinations to leaves (a) below, (b) at, and (c) above the flowering nodes (i.e. 2³ factorial). Yield was unaffected by treatments applied to leaves below the flowering nodes. Removal of leaves at flowering nodes did not reduce the number of pods but yield was reduced because there were fewer and smaller seeds. Inoculation of this zone also reduced yield; pods were lost at some nodes but it could also be shown that, irrespective of pod loss, yield at individual nodes was reduced in proportion to the severity of infection on leaves at the same nodes. Removal of leaves above flowering nodes reduced yield almost to the same extent as removal of leaves at flowering nodes but inoculation resulted in only a small amount of infection and yield was not reduced significantly. These results, taken in conjunction with recent studies on the physiology of the host plant, show that beans are exceptionally vulnerable to attack by B. fabae at the stage of flowering and early pod development. At later stages of development infection is unlikely to have a substantial effect on yield.