排序方式: 共有60条查询结果,搜索用时 15 毫秒
1.
2.
The effect of chemical crosslinking of invertase with a homo-bifunctional bisimidoester on its pH stability was studied. Dimethyl suberimidate (DMS) was used as the crosslinker and pH inactivation was investigated in the pH range of 2.5–10. The inactivation mechanisms of both native and DMS crosslinked invertases were observed to follow first-order kinetics during prolonged incubation. Although DMS crosslinking of invertase increased the pH stability of the enzyme over the complete pH range, it was especially effective over the acidic range. The half-lives of invertase increased almost twofold, on average, by crosslinking at the neutral to the acidic range. The effect of crosslinking was especially pronounced at pH 5 since both the half-life of the native invertase and the stabilization factor were very high. Higher activation free energies of inactivation were obtained for DMS crosslinked invertases over the whole pH range which also indicates the stabilization of invertase by crosslinking. 相似文献
3.
Turkoglu Z Bilgener S Ercisli S Bakir M Koc A Akbulut M Gercekcioglu R Gunes M Esitken A 《Genetics and molecular research : GMR》2010,9(4):2156-2165
Ten SSR loci, previously developed for Prunus, were analyzed to examine genetic relationships among 23 rootstock candidates for sweet and sour cherries, of the species P. avium, P. cerasus, P. mahaleb, and P. angustifolia. Five genotypes of P. laurocerasus, not used as rootstock, were included in the molecular analysis. The number of alleles per locus ranged from 8 to 12, with a mean of 9, while the number of microsatellite genotypes varied from 8 to 17, indicating that the SSRs were highly informative. The degree of heterozygosity (0.61) was high. Clustering analysis resulted in two main clusters. The first cluster was divided into two subclusters; the first subcluster consisted of P. avium and P. cerasus, and the second subcluster consisted of P. laurocerasus. The second cluster was divided into two subclusters. The first subcluster consisted of P. mahaleb genotypes and the second consisted of P. angustifolia genotypes. The reference rootstocks also clustered with their associated botanical species. Unweighted pair-group method with arithmetic mean analysis demonstrated that P. laurocerasus genotypes had less genetic variation and that P. avium genotypes were more closely related to P. cerasus. The SSR-based phylogeny was generally consistent with Prunus taxonomy information, suggesting the applicability of SSR analysis for genotyping and phylogenetic studies in the genus Prunus. 相似文献
4.
SUMO conjugation is a key regulator of the cellular response to DNA replication stress, acting in part to control recombination at stalled DNA replication forks. Here we examine recombination-related phenotypes in yeast mutants defective for the SUMO de-conjugating/chain-editing enzyme Ulp2p. We find that spontaneous recombination is elevated in ulp2 strains and that recombination DNA repair is essential for ulp2 survival. In contrast to other SUMO pathway mutants, however, the frequency of spontaneous chromosome rearrangements is markedly reduced in ulp2 strains, and some types of rearrangements arising through recombination can apparently not be tolerated. In investigating the basis for this, we find DNA repair foci do not disassemble in ulp2 cells during recovery from the replication fork-blocking drug methyl methanesulfonate (MMS), corresponding with an accumulation of X-shaped recombination intermediates. ulp2 cells satisfy the DNA damage checkpoint during MMS recovery and commit to chromosome segregation with similar kinetics to wild-type cells. However, sister chromatids fail to disjoin, resulting in abortive chromosome segregation and cell lethality. This chromosome segregation defect can be rescued by overproducing the anti-recombinase Srs2p, indicating that recombination plays an underlying causal role in blocking chromatid separation. Overall, our results are consistent with a role for Ulp2p in preventing the formation of DNA lesions that must be repaired through recombination. At the same time, Ulp2p is also required to either suppress or resolve recombination-induced attachments between sister chromatids. These opposing defects may synergize to greatly increase the toxicity of DNA replication stress. 相似文献
5.
SO Bafeel IA Arif MA Bakir AA Al Homaidan AH Al Farhan HA Khan 《Genetics and molecular research : GMR》2012,11(3):1934-1941
DNA barcoding is currently gaining popularity due to its simplicity and high accuracy as compared to the complexity and subjective biases associated with morphology-based identification of taxa. The standard chloroplast DNA barcode for land plants recommended by the Consortium for the Barcode of Life (CBOL) plant working group needs to be evaluated for a wide range of plant species. We therefore tested the potential of the rbcL marker for the identification of wild plants belonging to diverse families of arid regions. Maximum likelihood tree analysis was performed to evaluate the discriminatory power of the rbcL gene. Our findings showed that using rbcL gene sequences enabled identification of the majority of the samples (92%) to genus level and only 17% to species level. 相似文献
6.
In this study, a new system composed of two modules (electromyostimulation + electromyography recording) is presented. It can analyze in real time EMG signals during electromyostimulation. In addition, we propose a new method based on wavelet decomposition to analyze changes in M-wave characteristics. It leads to introduce a new index related to muscular fatigue. 相似文献
7.
Ariyasinghe A Morshed SR Mannoor MK Bakir HY Kawamura H Miyaji C Nagura T Kawamura T Watanabe H Sekikawa H Abo T 《The Journal of parasitology》2006,92(3):531-538
Mice were fed ad libitum with a normal diet (25% protein) or low-protein diets (0-12.5% protein) for a wk and then infected with a nonlethal or lethal strain of Plasmodium yoelii, that is, blood stage infection. The same diet was continued until recovery. Mice fed with a normal diet showed severe parasitemia during nonlethal infection, but survived the infection. They died within 2 wk in the case of lethal infection. However, all mice fed with low-protein diets survived without apparent parasitemia (there were small peaks of parasitemia) in cases of both nonlethal and lethal strains. These surviving mice were found to have acquired potent innate immunity, showing the expansion of NK1.1 -TCRint cells and the production of autoantibodies during malarial infection. Severe combined immunodeficiency (scid) mice, which lack TCRint cells as well as TCRhigh cells, did not survive after malarial infection of lethal strain of P. yoelii, even when low-protein diets were given. These results suggest that low-protein diets enhanced innate immunity and inversely decreased conventional immunity, and that these immunological deviations rendered mice resistant against malaria. The present outcome also reminds us of our experience in the field study of malaria, in which some inhabitants eventually avoided contracting malaria even after apparent malarial infection. 相似文献
8.
Enzyme immunoassay (EIA) in the rapid diagnosis of gonorrhoea 总被引:1,自引:0,他引:1
A Hossain T M Bakir M Siddiqui S De Silva 《Journal of hygiene, epidemiology, microbiology, and immunology》1988,32(4):425-431
The diagnostic value of a new, modified enzyme immunoassay (EIA) (Gonozyme; Abbott Laboratories, North Chicago III) was evaluated for the rapid antigenic detection of Neisseria gonorrhoeae in endocervical and urethral specimens. EIA results were compared with those of Gram stain (GS) and conventional culture tests. EIA sensitivity and specificity for male patients attending dermatovenerological clinic were 100% and 96.8% respectively in comparison to 86.7% and 96.8% obtained by Gram staining. For female Obstetrics-Gynaecology patients EIA sensitivity of 100% was highly significant compared to 50% sensitivity by the Gram stain. In culture, 30 strains of N. gonorrhoeae were isolated from 125 male specimens and 2 from 105 specimens from females; this suggests a prevalence of N. gonorrhoeae of 24% in males and 1.9% in females. In vitro antibiotic sensitivity testing indicated 55% resistance to penicillin and 43% to ampicillin in these isolated strains; all were sensitive to erythromycin/tetracycline. 12% of the strains were beta-lactamase producers. 相似文献
9.
A Hossain T F Bakir M N Chowdhury E Kurstake 《Journal of hygiene, epidemiology, microbiology, and immunology》1991,35(3):325-335
The seroepidemiology of infection due to S. typhi and Brucella spp. in a sub-tropical, developing country of the Middle East was investigated in 130 children of age less than 1 to 15 years, 117 young adults (16-30 years) and in a further 40 adults (greater than 30 years) using an agglutination test to detect antibodies to of S. typhi, B. abortus and B. melitensis. Only 4.5% of the children's and adult's sera respectively showed the presence of antibodies to both O and H antigens of S. typhi with reciprocal titers greater than or equal to 80. Prevalence rates of 11.6%, 11.3% respectively in children and adults of antibodies to B. abortus with reciprocal titers greater than or equal to 80 and similarly 13.1%, 12.4% to B. melitensis were found. The usefulness of a single Widal test to diagnose enteric fever in a non-endemic area and the agglutination test in the diagnosis of brucellosis in an endemic area was investigated. Of 244 patients with suspected enteric fever, the sera of 100 showed reciprocal antibody titers 80 to both O and H antigens and included in these were 8 patients with concurrent culture positivity. Among 138 children and adults with suspected brucellosis, 29 culture proven cases where serologically confirmed and a further 90 were detected serologically. The sera of all the culture proven cases exhibited antibody reciprocal titer greater than or equal to 640. A similar antibody response was noted in seventy-two of the culture negative cases diagnosed serologically for brucellosis. In culture proven, cases B. melitensis was the isolate. Comparative evaluation indicated the potential usefulness of the Rose Bengal Antigen Slide Agglutination Test (Brucelloside Test) as a screening test in the serodiagnosis of human brucellosis. 相似文献
10.