Biologically active <Emphasis Type="Italic">cis</Emphasis>-cinnamic acid occurs naturally in <Emphasis Type="Italic">Brassica parachinensis</Emphasis>

The biologically active cis-cinnamic acid (cis-CA) has been perceived as a synthetic plant growth regulator for decades,However,in the present study,we found that cis-CA actually exists as a naturally occurring compound in a Brassica plant,This natural growth-regulating substance presents in both the sunlight-irradiated leaf tissue and the non-irradiated root tissue ,The concentrations of cis-CA in both tissues are comparable to the bilogi-cally effective lvels of those major plant hormones,the presence of cis-CA in root tissue suggests that it may be produced through both light-dependent and -independent path-ways or it can be transproted from a plant organ to another.     

Ubi1 intron-mediated enhancement of the expression of Bt cry1Ah gene in transgenic maize （Zea mays L.）

The cry1Ah gene was one of novel insecticidal genes cloned from Bacillus thuringiensis isolate BT8. Two plant expression vectors containing cry1Ah gene were constructed. The first intron of maize ubiqutinl gene was inserted between the maize Ubiquitin promoter and cry1Ah gene in one of the plant expressing vectors （pUUOAH）. The two vectors were introduced into maize immature embryonic calli by microprojectile bombardment, and the reproductively plants were acquired. PCR and Southern blot analysis showed that foreign genes had been integrated into maize genome and inherited to the next generation stably. The ELISA assay to T1 and T2 generation plants showed that the expression of CrylAh protein in the construct containing the ubil intron （pUUOAH） was 20% higher than that of the intronless construct （pUOAH）. Bioassay results showed that the transgenic maize harboring cry1Ah gene had high resistance to the Asian corn borers and the insecticidal activity of the transgenic maize containing the ubil intron was higher than that of the intronless construct. These results indicated that the maize ubil intron can enhance the expression of the Bt cry1Ah gene in transgenic maize efficiently     

Comparative study of Cambrian lobopods <Emphasis Type="Italic">Miraluolishania</Emphasis> and <Emphasis Type="Italic">Luolishania</Emphasis>

The rare fossil Miraluolishania described by Liu et ah from the Lower Cambrian Chengjiang Lagerstatte in 2004 is regarded as an arthropod sphinx because it bears mosaic features of both Iobopods and arthropods. The discovery of this rare transitional form offers direct fossil evidence for exploring the relationship between Iobopods and arthropods. However, some scientists consider Miraluolishania to be a junior synonym of Luolishania because the former superficially resembles the latter in general appearance. Considering the significant differences between the two taxa, a thorough comparative study of Miraluolishania and Luolishania leads to the conclusion that there are definitely two different genera. Nevertheless, the ＂Luolishania＂ of the Haikou area is indeed ＂Miraluolishania＂, whereas Luolishania is most likely the typical genus of the Maotianshan area of Chengjiang County.     

Agrobacterium tumefaciens-mediated Transformation of CryⅠA(b) gene to Trichoderma harzianum

In this study, Cry ⅠA(b) gene was successfully transferred into the biocontrol fungus Trichoderma harzianum with an efficiency of 60-180 transformants per 10^6 spores by using Agrobacterium tumefaciens-mediated transformation. Putative transformants were analyzed to test the presence of Cry ⅠA(b) gene by Southern blot. Most transformants contained a single T-DNA copy. RT-PCR analysis showed that the Cry ⅠA(b) gene was transcribed. Antifungal activities and insecticidal activities of the transformants were examined. There was no obvious difference in antifungal activities between the transformants and their wild strains. The modified mortalities of the transformants T1 and T2 were 69.57% and 91.30%, respectively. The tranformation system mediated by A. tumefaciens proved to be a powerful tool for the filamentous fungi transformation and functional genomic study with its high transformation frequency, simplicity of T-DNA integration, and genetic stability of transformants.     

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.     

Fermentation of xylose to produce ethanol by recombinant <Emphasis Type="Italic">Saccharomyces cerevisiae</Emphasis> strain containing <Emphasis Type="Italic">XYLA</Emphasis> and <Emphasis Type="Italic">XKS1</Emphasis>

Fermentation of the pentose sugar xylose to produce ethanol using lignocellulosic biomass would make bioethanol production economically more competitive. Saccharomyce cerevisise, an efficient ethanol producer, cannot utilize xylose because it lacks the ability to convert xylose to its isomer xylulose. In this study, XYLA gene encoding xylose isomerase (XI) from Thermoanaerobacter tengcongensis MB4T and XKS1 gene encoding xylulokinase (XK) from Pichia stipitis were cloned and functionally coexpressed in Saccharomyces cerevisiae EF-326 to construct a recombinant xylose-utilizing strain. The resulting strain S. cerevisiae EF 1014 not only grew on xylose as sole carbon source, but also produced ethanol under anaerobic conditions. Fermentations performed with different xylose concentrations at different temperatures demonstrated that the highest ethanol productivity was 0.11 g/g xylose when xylose concentration was provided at 50 g/L. Under this condition, 28.4% of xylose was consumed and 1.54 g/L xylitol was formed. An increasing fermentation temperature from 30℃ to 37℃ did not improve ethanol yield.     

Mapping of genetic modifiers of <Emphasis Type="Italic">Plcd1</Emphasis> in scant hair mice (<Emphasis Type="Italic">snthr</Emphasis><Superscript><Emphasis Type="Italic">1Bao</Emphasis></Superscript>)

The scant hair mutant mouse (locus symbol: snthr ^1Bao ) is a recessive mutation that originated in an ethylnitrosourea chemical carcinogenesis study using the DBA/2J inbred strain. The gene responsible for the mutation was previously determined to be phospholipase C, delta 1 (Plcd1; mutant allele symbol Plcd1 ^snthr1Bao ). To map the modifiers of Plcd1, an intercross (DBA/2J-snthr ^1Bao /snthr ^1Bao × C57BL/6J+/+) was conducted. The F2 mutant progeny exhibited a variety of alopecia phenotypes; all F2 mutants (n=507) were classified into 3 groups (mild, moderate, and severe alopecia) and genotyped based on 96 microsatellites. A major QTL was identified on mouse chromosome (mChr) 15 at 12 cM with an LOD score greater than 7 (P < 0.0001). Three minor QTLs were detected on mChr 2, 5, and 7 at 40, 84 and 48 cM, respectively. The QTLs on mChr 7 and 15 were associated with minor alopecia while the QTLs on mChr 2 and 5 were associated with moderate to severe alopecia. No antagonistic or synergistic effects among or between the 4 QTLs were found. Integrating the functions of the 4 potential regulatory QTLs and mutant Plcd1 ^snthr1Bao , we found that these QTLs might contribute to variations of scant hair severity by altering the Ca²⁺ signal pathways in mouse skin.     

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   

Attractiveness of tobacco volatiles induced by <Emphasis Type="Italic">Helicoverpa armigera</Emphasis> and <Emphasis Type="Italic">Helicoverpa assulta</Emphasis> to <Emphasis Type="Italic">Campoletis chlorideae</Emphasis>

The attraction of Helicoverpa armigera-and Helicoverpa assulta-induced and mechanical damage-induced tobacco volatiles to Campoletis chlorideae was investigated, and the induced volatiles were analyzed. In windtunnel, C. chlorideae was strongly attracted by herbivoreinduced tobacco volatiles. Mechanically damaged tobacco leaves, whether treated with caterpillar regurgitant or water,were more attractive to the parasitoid than undamaged tobacco leaves. GC-MS analysis revealed that only 4 compounds were released from undamaged tobacco leaves,whereas 13 compounds were commonly emitted from herbivore-infested and mechanically damaged tobacco leaves.Compound β-pinene was specifically induced by the infestation of H. armigera, and (Z)-3-hexenal was only induced by the infestation of H. armigera and H. assulta, whereas hexyl acetate was only induced by mechanical damage. Tobacco leaves infested by H. armigera and H. assulta released larger amounts of volatiles than undamaged tobacco leaves did.Tobacco leaves treated with artificial damage plus caterpillars regurgitant or water emitted the same levels of volatiles,which were higher than that emitted by undamaged tobacco leaves. The emission amounts of single compounds were also different between differently treated plants. The differences were large between herbivore-induced and mechanical damage-induced compounds, and small between H. armigeraand H.assulta-induced compounds, and among compounds emitted from mechanically damaged plants treated with water or caterpillar regurgitant.     

Synergistic defensive mechanism of phytochelatins and antioxidative enzymes in <Emphasis Type="Italic">Brassica chinensis</Emphasis> L. against Cd stress

Brassica chinensis L. was chosen and exposed to different concentrations of Cd exposure to evaluate its Cd-accumulating capacity and its potential cellular defensive mechanisms. Cd accumulation in the shoots and roots of B. chinensis was up to 1348.3±461.8 and 3761.0±795.0 mg per killogram of dry weight, respectively, under 200 μmol/L of Cd exposure. Increasing Cd accumulation in the plant was accompanied by rapid accumulation of phytochelatins （PCs）, and the sequestration of Cd by PCs provided a primary cellular mechanism for Cd detoxification and tolerance of B. chinensis. Furthermore, malondialdehyde formation, hydrogen peroxide content and antioxidative enzyme activities such as superoxide dismutase, catalase, guaiacol peroxidase and ascorbate peroxidase were observed in the shoots of Cd-stressed B. chinensis. Increasing enzyme activities in response to concentrations of 5 to 50 μmol/L Cd showed an efficient defense against oxidative stress, suggesting that the antioxidative system was a secondary defensive mechanism. These resulted in reduced free Cd damage and enhanced Cd accumulation and tolerance. Glutathione plays a pivotal role in these two detoxification pathways. In general, these results suggested that PCs and the antioxidative system are synergistic in combatting Cd-induced oxidative stress and that they play important roles in Cd detoxification of B. chinensis, and also give a deep understanding of the natural defensive mechanisms in plants under heavy metal stress.     

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.     

Deletion analysis of oligomycin PKS genes （olmA） in Streptomyces arermitilis

Gene deletion vector pXL05(pKC1139::△olmA1 △olmA4) was used to disrupt oligomycin PKS encoding genes (olmA ) in Streptomyces avermitilis CZ8-73, the producer of anthelmintic avermectins B and the cell growth inhibitor oligomycin, olmA gene cluster in the chromosome was displaced by deletion allele on the plasmid via double crossover. Four of disruptants were confirmed by Southern blotting. Shaking flask experiments and HPLC analyses showed that the four mutants no longer produced the toxic oligomycin, but only made four components of avermectins B, which were avermectin Bla, Blb, B2a, B2b. The yields of avermectins B in these mutants were separately equal to those in CZ8-73. This revealed that olmA genes deletion did not affect the biosynthesis of avermectins. The deletion mutants were proved to be genetically stable, and thus might be promising strains in industrial production of avermectins B.     

Genetic diversity in the male-specific <Emphasis Type="Italic">SRY</Emphasis> gene of <Emphasis Type="Italic">Lepus yarkandensis</Emphasis>

Lepus yarkandensis, an endemic hare species in the Tarim Basin of China, has been suffering from habitat fragmentation due to desert expansion. To evaluate the effect of habitat fragmentation on its genetic diversity, the genetic diversity based on male-specific SRY gene marker is examined. A relatively low level of SRY genetic diversity is found compared to previous studies with mtDNA data, possibly due to the low SRY mutation rate and positive selection. Furthermore, one haplotype exists in eight populations along the Tarim River but not in many other relatively isolated populations, suggesting that habitat fragmentation may affect population divergence. Despite this, our pairwise Fst analysis shows no significant differentiation among populations, and this may be mainly caused by positive selection on the SRY gene in that 88 percent of individuals share the same haplotype. Finally, the phylogenetic analysis shows deep differentiation between L. yarkandensis and other two hare species (L. capensis and L. europaeus).     

Properties of a class of groups on <Emphasis Type="Italic">Z</Emphasis><Subscript><Emphasis Type="Italic">m</Emphasis></Subscript>

In this paper, we obtain the factorization of direct production and order of group GL(n, Z _m ) in a simple method. Then we generalize some properties of GL(2, Z _p ) proposed by Huppert, and prove that the group \(GL\left( {2,{Z_{{z^\lambda }}}} \right)\) is solvable. We also prove that group GL(n, Z _p ) is solvable if and only if GL(n, Z _p ) is solvable, and list the generators of groups GL(n, Z _p ) and SL(n, Z _p ). At last, we prove that PSL(2, Z _p )(p > 3) and PSL(n, Z _p )(n > 3) are simple.     

Rate constants for the reaction of ozone with <Emphasis Type="Italic">n</Emphasis>-butyl, <Emphasis Type="Italic">s</Emphasis>-butyl and <Emphasis Type="Italic">t</Emphasis>-butyl methyl sulfides

The rate constants for the ozone reactions with n-butyl methyl sulfide （n-BMS, CHaCH2CH2CH2SCH3）, sec-butyl methyl sulfide （s-BMS, CH3CH2（CH3）CHSCHa） and tert-butyl methyl sulfide （t-BMS, （CH3）3CSCH3） were measured using our smog chamber under supposedly pseudo-first-order conditions at 30002 K and 760 Torr. The experimental determined rate constants for n-butyl, s-butyl and t-butyl methyl sulfide are （1.23 ± 0.06）×10-19, （5.08 ± 0.19）×10-20 and （2.26 ± 0.14）×10-20 cm3 molecule-1· s-1, respectively. The reactivity-structure relationship of the reactions was discussed and used to illustrate the mechanism of the ozone reaction with thioethers. The results enrich the kinetics data of atmospheric chemistry.     

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.     

The enoyl-ACP reductase gene, <Emphasis Type="Italic">fabI1</Emphasis>, of <Emphasis Type="Italic">Sinorhizobium meliloti</Emphasis> is involved in salt tolerance,swarming mobility and nodulation efficiency

Our previous work showed that an enoyl-ACP reductase gene fabI1 of Sinorhizobium meliloti was down-regulated in the nifA mutant nodule bacteria. To gain a better understanding of fabI1 gene, a single site insertion mutant was constructed in this study. The fabI1 mutant was retarded in cell growth, and its ability to grow on media with high concentration of NaCl was reduced. In addition, the mutant was completely defective in swarming phenotype. During symbiosis, the fabI1 mutant had delayed nodule formation...     

Asian origin for Polystichum （Dryopteridaceae） based on rbcL sequences

Chloroplast rbcL sequences of 60 species of Polystichum sensu lato (s.l.), including 23 new sequences from southwest China, were used to assess the phylogenetic relationships within the genus. On the basis of estimated evolution rate of rbcL gene and the genetic distance data that passed relative-rate tests, we further estimated the divergence times between some clades of the genus. The phylogenetic relationships were inferred using the neighbor-joining and maximum-parsimony methods, both methods producing trees with completely congruent topology. These trees reveal that all species of Polystichum s.l. in this study (including Cyrtomium and Cyrtomidictyum) form a monophyletic group. The basal split in Polystichum s.l. separates a clade with all Asian members from a clade containing other species from all over the world. The phylogenetic and divergence time estimation results lead us to suggest that Polystichum s.l. originated in Asia in the late Late Cretacous (≈76 Ma) and migrated into other places in the world in early Eocene(≈46 Ma).