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1.
The effect of icariin on the bone resorption activity of rabbit osteoclasts is assessed in vitro. Osteoclasts were isolated from Japanese white rabbits and cultured on plates with a sterilized bone slice in each well. After treatment with icariin at various concentrations, the bone resorption activity of osteoclasts was evaluated by examining pit areas, superoxide anion (·O2-) generation, size and number of actin rings and intracellular calcium concentration [Ca2 ]i. As revealed by these data, icariin elicited continuous decline of [Ca2 ]i, making actin ring constricted and ·O2- generation decreased. These events resulted in smaller and fewer pits which indicate suppressed bone resorption activity of rabbit osteoclasts by icariin.  相似文献   

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Insertional mutagenesis based on maize Activator/Dissociator (Ac/Ds) transposons is becoming a ma- jor approach used to produce a saturated mutant collection in rice. In this research, Ds-T-DNA trans- formed homozygotes were crossed with Ac-T-DNA transformed homozygotes in order to establish an Ac/Ds transposon system in rice. The successive investigation of Ds transposition from F1 to F5 gen- erations indicated that the frequencies of germinal transposition increased over successive genera- tions and reached 54.2% in F3 generation. The Ds transposition pattern revealed that a Ds transposition induced an approximately 170-bp deletion of T-DNA sequence and another Ds transposition carried a 272-bp T-DNA sequence. Using thermal asymmetric interlaced PCR (TAIL-PCR), some flanking se- quences of the Ds element were amplified. Analyses of 17 Ds-flanking sequences showed that five Ds were inserted into gene regions. The Ds could transpose not only to the linked sites but also to the unlinked sites. The frequency of inter-chromosomal transposition of Ds was 33.3%.  相似文献   

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Asymmetric epoxidation of α,β-unsaturated ketones has been extensively studied and several important procedures have been developed in the last decade. This review addresses the most significant advances in asymmetric epoxidation of α,β-unsaturated ketones using proline-derived α,α-diarylprolinols as catalysts. Special attention has been paid to the enantioselective epoxidation of chalcones, α,β-unsaturated trifluoromethyl, trichloromethyl ketones and β,γ-unsaturated α-keto esters based on the reseach of our group.  相似文献   

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The R- and AR-indices: Complementing the h-index   总被引:47,自引:0,他引:47  
Based on the foundation laid by the h-index we introduce and study the R- and AR-indices. These new indices eliminate some of the disadvantages of the h-index, especially when they are used in combina-tion with the h-index. The R-index measures the h-core’s citation intensity, while AR goes one step further and takes the age of publications into account. This allows for an index that can actually in-crease and decrease over time. We propose the pair (h, AR) as a meaningful indicator for research evaluation. We further prove a relation characterizing the h-index in the power law model.  相似文献   

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Endocasts are important materials used for the study of human brain evolution, and allow examination of the external features of brain anatomy from the inside the cranium. Studies examining brain asymmetries in fossil hominids are usually limited to scoring of differences in hemisphere protrusion rostrally and caudally, or to comparing the width of the hemispheres. In the present study, using 3D laser scanning, we examined asymmetries of the hemisphere volumes and surface areas in the Zhoukoudain (ZKD) Homo erectus, dated to 0.4–0.8 Ma. Compared with modern endocasts, we found that the absolute hemisphere volumes and surface areas exhibited no significant asymmetries in the ZKD or in modern specimens. However, the relative hemisphere volumes against surface areas differed between the two groups. When comparing the relative sizes between the left and right hemispheres, the ZKD specimens exhibited a greater variation than in the modern humans; there were no differences in the two hemispheres in the ZKD specimens, while in the modern endocasts the left hemisphere was significantly greater than the right hemisphere. These data suggest that brain asymmetries originated from relative brain sizes rather than absolute brain volumes during human evolution. These anatomical changes are likely related to the origin of human brain lateralization.  相似文献   

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Mobile genomic islands (GIs) can be excised from the chromosome, then form a circular intermediate and be reintegrated into the chromosome by the GI internal integrase. Some mobile GIs can also be transferred into a new receptor cell by transformation, conjugation, or transduction. The action sites of the integrase are usually flanked direct repeats (DRs) of the GIs. Accurate localization of the flanking sequences is a precondition for determining the mobility of the GI. Mobile GIs are generally associated with transfer RNAs (tRNAs). Based on the correlation between flanking sequences and tRNA sequences, the flanking sequences of 11 putative mobile GIs in Pseudomonas aeruginosa PAO1, P. aeruginosa PA14, P. fluorescens Pf-5 and P. fluorescens Pf0-1 were identified. Among the 11 GIs, Pf0-1GI-1 is responsible for benzoate degradation. PAO1GI-1, Pf5GI-2, Pf5GI-3, and Pf5GI-4 were confirmed experimentally to be excised from a chromosome to form a circular intermediate. The action sites of the integrases are these GIs direct repeats. Due to distinct DRs, cutting sites for the internal integrase of PAO1GI-1, Pf5GI-2, Pf5GI-3 and Pf5GI-4 were determined outside the T-loop of the tRNAGly gene, outside the anticodon loop of the tRNASer gene and tRNALys gene, and at the asymmetric 3′-end of the tRNALeu gene, respectively. PAO1GI-1 and other mobile GIs may be transferred into many different strains that belong to different phyla because of the clear flanking sequences. This study describes basic information about the action sites of the integrases, assesses the mobility of GIs, and can help design and transfer mobile GIs to candidate strains.  相似文献   

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To assess the interaction effect between cadmium (Cd) and 17-estradiol (E2),male Chinese loaches (Misgurnus anguillicaudatus) were exposed to E2 (1 g/L) and Cd (50 or 500 g/L) alone and in combination using a semi-static waterborne exposure system.The effects of E2 on the accumulation and distribution of Cd,as well as the effects of Cd on vitellogenin (Vtg) synthesis induced by E2,were investigated.Cd mainly accumulated in the kidneys,liver,intestines,and gills,with little amounts in muscles,bones,and gonads.Co-exposure with E2 did not change the main targets for Cd.E2 could induce Vtg synthesis in male Chinese loaches,and co-exposure with 50 or 500 g/L Cd could inhibit the Vtg induced by 1 g/L E2.Compared with the results reported in the literature,it can be concluded that factors such as fish species,Cd dosage,and manner of exposure might make contributions to the interaction between Cd and E2.Our results also suggested that male Chinese loaches are susceptible to Cd,and can be recommended as a potential sentinel species to study the ecotoxicology of heavy metals.  相似文献   

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Microcystins are a kind of cyclic hepatoxins produced by many species of cyanobacteria. Most previous work have been done on the toxic effects of microcystins on animals and plants. However, the reports about the effect of microcystins on microbial cells are very limited. In this work, the permeability of MC-RR on the cell outer membrane of Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis) was discussed. The permeability effect of MC-RR on the cell outer membrane of E. coli and B. subtilis under different concentrations was demonstrated by a rapid and sustained reduction in the A675 values of lysozyme-treated cells. The decrease of the absorbance values showed a time- and dose-effect. The extravasations of protein and carbonhydrate increased with the increment of the treated-concentration of MC-RR. The results showed that MC-RR could increase the permeability of cell outer membranes of E. coli and B. subtilis. The synergistic effects of MC-RR and lysozyme on bacteria indicated that MC-RR might play an ecological role in bacteria in combination with other substances in some aquatic environments.  相似文献   

11.
Gene expression of glutathione peroxidase 3 (ATGPX3) in response to osmotic stress was analyzed in Arabidopsis using ATGPX3 promoter-glucuronidase (GUS) transgenic plants. High levels of GUS ex- pression were detected under osmotic stress in ATGPX3 promoter-GUS transgenic plants. Compared with the wild type, the growth and development of ATGPX3 mutants (atgpx3-1) were more sensitive to mannitol. In addition, the expression of RD29A, ABI1, ABI2 and RbohD in atgpx3-1 was induced by ABA stress. These results suggest that ATGPX3 might be involved in the signal transduction of osmotic stress.  相似文献   

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The principles of the new maximal operator H* we defined are discussed. We prove that it is bounded from martingale Hardy-Lorentz L^Xp.q[0,1) to the Lorentz L^Xp.q[0,1) for 1/2〈 p〈∞, 0〈~ q ≤ ∞, where X is any Banach space. When the Banach space X has the RN property, the sequence dnHnf converges to f a.e. Meanwhile the convergence in L^Xp norm for 1≤p〈∞ is a consequence of that the family functions K (n∈N) is an approximate identity.  相似文献   

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A water-soluble substance was extracted from the Chinese herb, Alternantheraphiloxcroides with hot water and alcohol. Aliquots of this initial extract were further fractionated by treatment with ether, ethyl acetate and alcohol respectively. The four extracts were assayed for anti-viral activity against three serum, Hantaan virus 114 (HV114), HV435 and A9 strains. Results show that the four extracts are capable of inhibiting Hantaan virus propagation, of which extract No. 1 has the best efficiency. The three dosage of extract No. 1, which are used upon three Hantaan virus serum IC50, are 153, 157, 154 μg/mL. New-born mice were made to be infected with HV114 and then fed in vivo with extract No.l on the 3rd, 10th and 14th days after being infected by the virus. The treatment continued for 8 days with a dosage of 2.5 g/kg. Result shows that survival rates of mice were 75%, 50% and 0, respectively. The median time to death (MTDs) of the three groups were 37, 30, 23 days.  相似文献   

16.
In order to develop an efficient identification method for Fallopia plants and drugs, molecular analysis of the partial matK gene sequences was performed on 6 Fallopia species. Based on the matK sequences, a phylogenetic tree was constructed, which showed that different populations of inter- and intra-species could be specified and distinguished. The matK gene sequences of the 6 Fallopia species were all found to be of 1 271 bp in length, with some nucleotide variations throughout the entire sequences. The nucleotide difference at position 1 041 could distinguish F. denticulata from others, while specific nucleotide at position 1 154 became identification markers for F. aubertii. Moreover, four specific marker sites for F. multiflora var. ciliinerve at positions 216, 224, 1 060 and 1 179, seven for F. convolvulus at 318, 765, 772, 874, 936, 952 and 1 036, and seven for F. dentate alata at 111, 192, 366, 450, 457, 1 032 and 1 074 were also observed. By detecting the marker nucleotides and analyzing the phylogenetic relationship, the botanical origins of five inspected drugs were determined, suggesting that matK sequences can be used for authenticating Fallopia plants and drugs.  相似文献   

17.
Cadmium-metallothionein (Cd-MT) of Pteria penguin was used to immunize domestic rabbit in order to obtain polyclonal antibody against Cd-MT. Using the anti-Cd-MT antibody, a method of indirect non-competitive enzyme-linked immunosorbent assay (non-competitive ELISA) was established to detect shellfish Cd-MT. In this case, the minimum detectable concentration of P. penguin Cd-MT was (4.563±0.051) ng/mL. The linear range of detection was 9.75-2.0×104 ng/mL. Intra-assay relative standard deviation (RSD) was less than 11.6%, and inter-assay RSD less than 6.7%. The recovery rates ranged from 83.7% to 119.0%. The polyclonal antibody against Cd-MT of P. penguin can also be used to detect MT of other four types of shellfish. In the crude extracts from different organs of P. penguin, the MT concentrations determined by this method matched well with the concentrations of cadmium detected by the atomic absorption spectroscopy.  相似文献   

18.
The functional analysis of dr1127,a novel gene in Deinococcus radiodurans was performed in this pa-per. The dr1127 gene was found occasionally in our microarray and 2-DE gel experiments. Mutation of the dr1127 gene decreased the γ-radiation and H2O2 resistance of D. radiodurans,and weakened the scavenging abilities of cell extracts for free radicals (superoxide anion,hydrogen peroxide,and hy-droxyl radical). Further oxidative damage assays demonstrated that the purified DR1127 protein of D. radiodurans could bind to double stranded DNA in vitro and protect DNA from oxidative damage in this way. These results suggest that the dr1127 gene is an important gene that can maintain γ-radiation and oxidative resistance in D. radiodurans and may take part in the oxidative stress process.  相似文献   

19.
Rice blast, caused by the fungal pathogen Magnaporthe oryzae, is one of the most devastating crop diseases worldwide. The avirulence gene corresponding to rice blast resistance gene Pi7 in field isolate CHL346 was inherited as a single gene, designated AvrPi7, in a segregating population consisting of 189 ascospore progenies derived from a cross between field isolates CHL346 and CHL42. In order to determine the chromosomal location of the AvrPi7 locus, a total of 121 simple sequence repeat (SSR) markers were developed based on the whole-genome sequence of reference isolate 70-15 of M. oryzae. Linkage analysis of the locus with these SSR markers showed that eight SSR markers on chromosome 1 were linked to the locus, among which the closest flanking markers MS1-9 and MS1-15 were 3.2 and 16.4 cM from the locus, respectively. For fine mapping, additional PCR-based makers including eight SSR markers and three candidate avirulence gene (CAG) markers were developed in the region flanking both markers. The AvrPi7 locus was genetically delimited within a 1.6-cM region flanked by markers MS1-21 and MS1-22, and co-segregated with the marker CAG2. To construct a physical map of the AvrPi7 locus, molecular markers linked to the Avr gene were mapped on the supercontigs of the ref-erence isolate 70-15 through bioinformation analysis (BIA). Consequently, the AvrPi7 locus was delim-ited to a 75-kb interval flanked by markers MS1-21 and MS1-22 based on the reference sequence. Merodiploids observed in this study are also discussed.  相似文献   

20.
Uropathogenic Escherichia coli (UPEC) is the most common causative organism of human urinary tract infection (UTI). Several UPEC virulence factors have been identified, but more are yet to be found. We previously identified a novel 789-bp-long DNA fragment (named R049) in UPEC strain 132 using a suppressive subtractive hybridization technique. In the present study, we used genome walking to elongate the sequence of this fragment to obtain the whole gene sequence and examined the role of this gene product in generating protective immunity. Through bioinformatic analysis, we predicted that this gene is a 1311-bp open reading frame (ORF), which we designated ORFR049 (GenBank accession No.: EF488001). We further constructed a prokaryotic expression system to express full recombinant R049 protein and isolated and purified the protein through IPTG induction and nickel affinity chromatography. Using mouse immunosera generated by the purified protein, we confirmed the natural expression and outer membrane localization of the protein in wild-type strain UPEC132 by Western blotting. To test the potential of this protein as a vaccine candidate, we immunized mice with the recombinant protein before challenging them with UPEC132 through the urinary tract. The results showed significantly reduced bacterial colonization in the urine and kidneys of the immunization group compared with the control group. However, the degree of renal pathological damage was not significantly improved in the immunized mice. Our study has identified a novel gene of UPEC which can generate protective immunity against UTI. This novel gene provides a promising new vaccine candidate.  相似文献   

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