Phytosterol of <Emphasis Type="Italic">Potamogeton maackianus</Emphasis> and its change under the stress of <Emphasis Type="Italic">Microcystis aeruginosa</Emphasis>

The phytosterol in Potamogeton maackianus was identified and quantified. From the hexane extracts analysis of unsaponifiable fraction of P. maackianus by gas chromatography-mass spectrometry(GC-MS), campesterol, stigmasterol and β-sitosterol were the main phytosterols in P. maackianus with the contents of 0.368, 1.17 and 0.824 mg·g⁻¹, respectively. After 7 days’ exposure under M. aeruginosa, the contents of campesterol, stigmasterol and β-sitosterol in P.maackianus increased by 23.1%, 40.4% and 40.8%, respectively. Both the contents of 24-ethyl sterols (sitosterol and stigmasterol) and 24-methyl sterol (campesterol) in macrophytes increased, but the percentage of total sterol composition did not change significantly. This result indicated that the content of 4-demethyl sterols and the second alkylation of the phytosterol side-chain at C-24 in P. maackianus were affected by M. aeruginosa. Biography: ZHANG Shenghua(1979–), female, Ph.D. candidate, research direction: environmental biology.     

Characterizations of <Emphasis Type="Italic">L</Emphasis><Subscript><Emphasis Type="Italic">p</Emphasis></Subscript>(<Emphasis Type="Italic">R</Emphasis>) using tight wavelet frames

In this paper,a Littlewood-Paley function characterization of the spaces L p(R),1相似文献   

Analysis of type II toxin-antitoxin genes <Emphasis Type="Italic">all</Emphasis> 3211-<Emphasis Type="Italic">asl</Emphasis> 3212 in <Emphasis Type="Italic">Anabaena</Emphasis> PCC 7120

The type II toxin-antitoxin genes are responsible for the phenotypic switch to a quasi-dormant state that enables cell survival under stresses, a similar function to heterocyst of cyanobacteria. In this paper, we particularly study the role of gene pair all3211-asl3212 under Spectinomycin stress to reveal how the type II toxin-antitoxin involved in environmental stress responses. Bioinformatics prediction shows that toxin protein gene All3211 is homologous to MazF, a member of mazEF family that encoding nucleases. We clone gene all3211-asl3212 into expression vectors to identify its molecular characteristics. Deletion mutant strains of all3211-asl3212 are selected in a tri-parental mating screen. Phenotype comparisons of mutant and wild type reveals no difference of single-deletion-mutants in pigment integrity, the sensitivity to antibiotics, and heterocyst formation. The results show that deletion mutation of single TAS gene pair all3211-asl3212 results in limited effects on the cellular growth of PCC 7120. Thus, we suggest that dosage compensating might be provided from redundant genes or bypass pathways to offset obvious phenotypic differences.     

Evaluation of the occurrence possibility of SNP in <Emphasis Type=Italic>Brassica napus</Emphasis> with sliding window features by using RBF networks

We extract some physical and chemical features re-lated to the occurrence of single nucleotide polymorphism (SNP) from three groups of sliding windows around SNP site,and then make the predictions about accuracy by using radial basis function (RBF) networks. The result of the forward sliding windows sug-gests that the accuracies and Matthews correlation coefficient (MCC values) ascend with the increasing of length of sliding windows. The accuracies range from 73.27 % to 80.69 %,and MCC values range from 0.465 to 0.614. The backward sliding windows and the sliding windows with fixed length three are de-signed to find the crucial sites related to SNP. The results imply that the occurrence possibility of SNP relies heavily on the above physical and chemical features of sites which are at a distance around 20 bases from the SNP site. Compared with the support vector machine (SVM),our RBF network approach has achieved more satisfactory results.     

On reverses of the <Emphasis Type="Italic">L</Emphasis><Subscript><Emphasis Type="Italic">p</Emphasis></Subscript>-Busemann-Petty centroid inequality and its applications

In this paper,the reverse forms of the L p-Busemann-Petty centroid inequality are shown. As the applications of the reverse forms,we obtain the reverse forms of the L p-centroid-affine inequality and an upper bound of the isotropic constant for convex bodies.     

Effect of acetazolamide on stable carbon isotope fractionation in <Emphasis Type="Italic">Chlamydomonas reinhardtii</Emphasis> and <Emphasis Type="Italic">Chlorella vulgaris</Emphasis>

The effect of extracellular carbonic anhydrase (CAex) on stable carbon isotope fractionation in algae is still unclear. The stable carbon isotope composition and algal growth in the presence and absence of the membrane-impermeable CA inhibitor acetazolamide were compared in Chlamydomonas reinhardtii and Chlorella vulgaris. The CAex of both algal species contributed about 9‰ of the stable carbon isotope fractionation and exhibited a dosage effect. Therefore, evidence in vivo that CAex leads to a larger carbon isotope fractionation of algae is presented.     

<Emphasis Type="Italic">Malvastrum yellow vein virus</Emphasis>, a new<Emphasis Type="Italic">Begomovirus</Emphasis> species associated with satellite DNA molecule

Virus isolate Y47 was obtained fromMalvastrum coromandelianum showing yellow vein symptom in Honghe, Yunnan Province. The complete nucleotide sequence of DNA-A was determined, it contains 2731 nucleotides, having typical genomic organization of a begomovirus, encoding 6 ORFs with 2 ORFs [AV1(CP) and AV2] in virionsense DNA and 4 ORFs (AC1–AC4) in complementarysense DNA. Comparisons show that the total DNA-A of Y47 has the highest sequence identity (77%) with that ofOkra yellow vein mosaic virus- [201] (AJ002451), while less than 76% identities are found when compared with other begomoviruses. The molecular data show that virus isolate Y47 is a distinct begomovirus species, for which the nameMalvastrum yellow vein virus is proposed. Satellite DNA molecule (Y47β) was found to be associated with Y47 using the primers (beta01 and beta02) specific for DNAβ. Y47β consists of 1348 nucleotides, with a functional ORF (C1) in complementary-sense DNA. Y47β has 62%–67% sequence identity with DNAβ molecule associated withCotton leaf curl Multan virus orCotton leaf curl Rajasthan virus, while lower than 46% sequence identities are found when compared with other reported DNAβ molecules. Relationship dendrograms show that DNAβ molecules are co-evolved with their help begomoviruses.     

Anatomy and plant affinity of <Emphasis Type="Italic">Chuaria</Emphasis>

Chuaria is one of the few globally distributed macrofossil pioneers documented in the Precambrian. It is perhaps the most controversial fossil in term of its affinity despite more than one hundred years of study. Many mutually exclusive affinities have been suggested for this frequently encountered fossil. Although often treated as a multicellular alga, this interpretation remains inconclusive because the lacking unambiguous demonstration of cellular structures. In this paper the cellular details of Chuaria are clearly revealed for the first time. The cell walls in Chuaria suggest that it is a multicellular eukaryotic alga, in agreement with the latest biogeochemical analyses. Different thicknesses of cell walls suggest primary cellular differentiation in this organism. Membrane-like structures within the cells (the first to be reported in Precambrian fossils) imply a eukaryotic nature. This study partially resolves the century-long controversy over the affinity of Chuaria, and makes Chuaria one of the few recognized multicellular eukaryotes before the Neoproterozoic glaciation.     

<Emphasis Type="Italic">Lp</Emphasis>-dual mixed geominimal surface area

In this paper, a new Lp-dual mixed geominimal surface area is defined by Lp-dual mixed quermassintegrals, which extends the definition of Lp-dual geominimal surface area and generalizes some related inequalities established by Wan and Wang.     

Generalized inverse eigenvalue problem for (<Emphasis Type="Italic">P</Emphasis>,<Emphasis Type="Italic">Q</Emphasis>)-conjugate matrices and the associated approximation problem

In this paper, the generalized inverse eigenvalue problem for the (P,Q)-conjugate matrices and the associated approximation problem are discussed by using generalized singular value decomposition (GSVD). Moreover, the least residual problem of the above generalized inverse eigenvalue problem is studied by using the canonical correlation decomposition (CCD). The solutions to these problems are derived. Some numerical examples are given to illustrate the main results.     

Enhanced anti-sunward flow near local noon during a period of horizontal IMF and high solar wind velocity <Emphasis Type="Italic">V</Emphasis><Subscript><Emphasis Type="Italic">Y</Emphasis></Subscript>

It is believed that a southward interplanetary magnetic field (IMF) is mainly responsible for the energy input from solar wind into the magnetosphere. This paper presents an unusual case of strong anti-sunward plasma flow (up to 2 km/s) in the polar cap ionosphere and large cross-polar cap potential (CPCP) during a period of horizontal IMF (|B _Z | < 2 nT) observed by both ACE (at the L1 point) and Geotail (on the dusk flank of the magnetosheath). The CPCP is even higher than that under preceding B _Z ≈ −23 nT. Furthermore, GOES8 observed that the magnetosheath field turns northward as the anti-sunward plasma flow and CPCP start to increase, which implies that the magnetosheath field interacting with the Earth’s magnetopause has significantly rotated and differs from the IMF observed by ACE and Geotail. In accordance with previous theoretical work, we suggest that the magnetic field line draping produces a southward magnetosheath field and enhances anti-sunward plasma flow and the CPCP.     

Chronology and pattern of integration of tandem genomic islands associated with the tmRNA gene in <Emphasis Type="Italic">Escherichia coli</Emphasis> and <Emphasis Type="Italic">Salmonella enterica</Emphasis>

tmRNA,a combination of a tRNA-related fragment and a small mRNA fragment,was confirmed as the integration site of genomic islands(GIs).Using sequence alignment and comparative genomics,68 GIs associated with tmRNA genes were identified among 13 genera of Enterobacteriaceae.Among them,53 GIs were found in Escherichia coli and Salmonella enterica.Among these 53 GIs,tandem GIs were verified in eight S.enterica and two E.coli chromosomes.The downstream regions of the tmRNA genes in most of the E.coli and S.enterica chromosomes include one GI or tandem GIs region and a remnant variable region distal to the tmRNA.The chronology of integration of tandem GIs into the genome indicated that GIs farther from the tmRNA were incorporated into the genome earlier than those nearer from the tmRNA.The integrases of the tmRNA gene-associated GIs can be further categorized into three subtypes:HP1 integrases,PhiCTX integrases,and P4 integrases,which are the most predominant.The GIs were first integrated into the chromosome by the P4 integrase,subsequently by the PhiCTX integrase,and finally by the HP1 integrase.Thus,the tmRNA gene is an important site for investigating the genetics and evolution of tandem GIs.     

Effects of soil stoichiometry of the CaCO<Subscript>3</Subscript>/available phosphorus ratio on plant density in <Emphasis Type="Italic">Artemisia ordosica</Emphasis> communities

In soil, CaCO3 can reduce the availability of phosphorus in arid and semi-arid regions, thereby influencing plant growth. However, the effects of soil stoichiometry of the CaCO3/available phosphorus ratio (CaCO3/AP ratio) on plant density are unknown. In this study, we examined 4 Artemisia ordosica communities located in arid and semi-arid regions, and performed a pot experiment with an orthogonal design to examine the relationships between the soil CaCO3/AP ratio and plant density. The results showed that the soil stoichiometry of the CaCO3/AP ratio had a greater effect on growth of A. ordosica than either CaCO3 or AP as single factor. The influence of the soil CaCO3/AP ratio on density of A. ordosica was related to the climatic zone and the types and/or amplitudes of increases in the soil CaCO3/AP ratio. When the soil CaCO3/AP ratio was within the same amplitude and was less than 2.5, the A. ordosica density increased in the semi-arid region, whereas the density decreased with increasing soil CaCO3/AP ratios in the arid region. In the semi-arid region, when the soil CaCO3/AP ratio was within the same amplitude and the increase in the soil CaCO3 content was greater than the increase in soil AP, the A. ordosica density increased with increasing soil CaCO3/AP ratios. This means that the relationship between the soil CaCO3/AP ratio and the A. ordosica density remained the same. In the arid region, an increase in the soil CaCO3/AP ratio as a result of increased soil CaCO3 content and decreased soil AP resulted in increased density of A. ordosica. Therefore, the relationship between soil CaCO3/AP ratios and density of A. ordosica was altered by these changes in soil chemistry. Thus, the soil stoichiometry of the CaCO3/AP ratio is an important factor affecting the density of A. ordosica in arid and semi-arid regions.     

<Emphasis Type="Italic">L</Emphasis><Subscript>2</Subscript> decay estimate of BCL equation

This paper considers linearized BCL system with viscosity which is firstly derived by J. L. Bona, T. Colin and D. Lannes for the study of motion of water waves. L ₂ decay estimate is got by means of Fourier analysis and frequency decomposition. This result plays key role in studying the global well-posedness of corresponding nonlinear system.     

Improved zero-sum distinguisher for full round <Emphasis Type="Italic">Keccak-f</Emphasis> permutation

Keccak is one of the five hash functions selected for the final round of the SHA-3 competition,and its inner primitive is a permutation called Keccak-f.In this paper,we observe that for the inverse of the only nonlinear transformation in Keccak-f,the algebraic degree of any output coordinate and the one of the product of any two output coordinates are both 3,which is 2 less than its size of 5.Combining this observation with a proposition on the upper bound of the degree of iterated permutations,we improve the zero-sum distinguisher for the Keccak-f permutation with full 24 rounds by lowering the size of the zero-sum partition from 21590 to 21575.     

Direct observation of monomer film structure of bacteriochlorophyll <Emphasis Type="Italic">c</Emphasis>

The adsorption and assembling of bacteriochlorophyll c (BChl c) on a highly oriented pyrolytic graphite (HOPG) surface have been investigated by the scanning tunneling microscopy (STM). BChl c molecules are found to self-organize a well-defined adlayer on HOPG surface with a monomeric structure different from the dimer association seen on adlayers of Chls a, c and BChlide c, d. A structural model is proposed for the adlayer.     

Enhanced antioxidant capacities <Emphasis Type="Italic">in vivo</Emphasis> caused by the change in key constituent of <Emphasis Type="Italic">Terminalia chebula</Emphasis> Retz. treated with Tibet traditional process

In order to investigate the chemical-biological relationship caused by the special processing technology, the constituent’s content and antioxidant capacity in vivo of Euphorbia fischeriana Steud processing Terminalia chebula Retz. have been tested. Taking T. chebula Retz. as control, the content of gallic acid is analyzed with high performance liquid chromatography (HPLC) method. The results show that the increase of gallic acid concentration from 4.54% to 7.46% leads to enhancement of the antioxidant capacities in vivo of the E. fischeriana Steud processing T. chebula Retz. The significant antioxidant capacity in vivo (p<0.05) of the processed product possesses is better than the unprocessed herb. Its superoxide dismutase (SOD) and malondia-ldehyde (MDA) contents in serum, the MDA content in liver can match the effects of vitamine E when administered at high dosage.     

Microstructure and element composition of shell plates of <Emphasis Type="Italic">Liolophura japonica</Emphasis>

The microstructure characteristics of shell plates of chiton Liolophura japonica Lischke were analyzed using environmental scanning electron microscopy (ESEM). The results show that the internal structure of the shell plate of chiton Liolophura japonica is composed of seven calcium layers which were crossed lamellar crystallites, homogeneous structure, granular crystallites, and trabecular type crystallites. The element compositions of shell plates were analyzed using X-ray photoelectron spectroscopy (XPS)....