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排序方式: 共有538条查询结果,搜索用时 140 毫秒
81.
82.
Mayumi Fujiwara Nonio Nagao Kazuaki Monden Masashi Misumi Katsuhiro Kageyama Kiyotaka Yamamoto Nobuhiko Miwa 《Free radical research》1997,27(1):97-104
Bovine aortic endothelial BAE-2 cells exposed to the peroxidizing agent, tert-butylhydroperoxide (t-BuOOH) or 2,4-nonadienal (NDE), suffered from disruption of cell membrane integrity and from reduction of mitochondrial dehydrogenase activity as assessed by fluorometry using ethidium homodimer and photometry using WST-1, respectively. The cells were protected from t-BuOOH-induced injury more markedly by L-ascorbic acid-2-O-phosphate (Asc2P) stably masked at the 2,3-enediol moiety, which is responsible for the antioxidant ability of L-ascorbic acid (Asc), than by Asc itself. In contrast, NDE-induced membrane disruption but not mitochondrial dysfunction was prevented by Asc2P, whereas Asc exhibited no prevention against both types of injury. The amount of intracellular Asc was 7.2- to 9.0-fold larger in Asc2P-administered BAE-2 cells, where the intact form Asc2P was not detected, than in Asc-administered cells as assessed by HPLC of cell extract with detection by coulometric ECD and W. During transmembrane influx into the cell, Asc2P was concentrated as highly as 70- to 90-fold relative to the extracellular Asc2P concentration, whereas Asc was 8-to 13-fold concentrated as estimated based on an intracellular water content of 0.59 pL/cell determined by [14C]PEG/gas chromatography. Thus, Asc2P but not Asc is highly concentrated in the aqueous phase of the cell after prompt dephosphorylation, and may thereby render the cell more resistant to t-BuOOH-peroxidation assumedly via scavenging of intracellular reactive oxygen species than to peroxidation with the less hydroplulic agent NDE. 相似文献
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84.
Nadja Lepsch-Cunha Paulo Y. Kageyama Roland Vencovsky 《Biodiversity and Conservation》1999,8(9):1205-1218
We quantified the within-population genetic variation of Couratari multiflora and C. guianensis, two tree species found in terra firme forests of central Amazonia. Both species have some ecological features in common, but they differ in population abundance across their geographic ranges. While C. multiflora has been found only in low-density populations in all sites studied to date, C. guianensis is relatively common in some sites and very scarce in others. In a 400-ha plot, we found 41 and 29 adults of C. multiflora and C. guianensis, respectively. Twenty-two saplings of C. guianensis and 103 seedlings of C. multiflora were also examined. The mean expected heterozygosities (Hem) of seedlings and adults of C. multiflora were 0.431 and 0.436, and the mean fixation indices (Fm), 0.114 and 0.176, respectively. For C. guianensis, saplings and adults presented Hem equal to 0.425 and 0.429, and the Fm were 0.393 and 0.527, respectively. These low-density populations of two congeneric species did not differ in terms of genetic diversity, but rather they differed in terms of mean observed heterozygosity (Hom), and therefore Fm. The species with variable population density had lower Hom and greater Fm relative to the species that is always found in low-density. 相似文献
85.
86.
Tarazi R Moreno MA Gandara FB Ferraz EM Moraes ML Vinson CC Ciampi AY Vencovsky R Kageyama PY 《Genetics and molecular biology》2010,33(1):78-85
Dipteryx alata is a native fruit tree species of the cerrado (Brazilian savanna) that has great economic potential because of its multiple uses. Knowledge of how the genetic variability of this species is organized within and among populations would be useful for genetic conservation and breeding programs. We used nine simple sequence repeat (SSR) primers developed for Dipteryx odorata to evaluate the genetic structure of three populations of D. alata located in central Brazil based on a leaf sample analysis from 101 adults. The outcrossing rate was evaluated using 300 open-pollinated offspring from 25 seed-trees. Pollen dispersal was measured by parentage analysis. We used spatial genetic structure (SGS) to test the minimal distance for harvesting seeds in conservation and breeding programs. Our data indicate that the populations studied had a high degree of genetic diversity and population structure, as suggested by the high level of divergence among populations . The estimated outcrossing rate suggested a mixed mating system, and the intrapopulation fixation index was influenced by SGS. We conclude that seed harvesting for genetic conservation and breeding programs requires a minimum distance between trees of 196 m to avoid collecting seeds from related seed-trees. 相似文献
87.
Masaya Watanabe Fumiko Yukuhiro Taro Maeda Kazuki Miura Daisuke Kageyama 《Microbial ecology》2014,67(1):219-228
Spiroplasma, a group of small, wall-less, helical, and motile bacteria belonging to the Mollicutes, contains species with diverse life histories. To date, all the Spiroplasma strains that are known to be transmitted vertically in arthropod lineages belong to either the Spiroplasma ixodetis group or the Spiroplasma poulsonii group. Here, we found that a unique strain of Spiroplasma vertically transmitted in predatory flower bugs of the genus Orius belongs to the Spiroplasma insolitum group, which is a group of bacteria phylogenetically closely related to S. insolitum derived from the tickseed sunflower, Bidens sp. (Asterales: Asteraceae). The infection frequencies in natural populations were16.0 % in Orius sauteri (n?=?75), 40.5 % in Orius nagaii (n?=?37), and 8.0 % in Orius minutus (n?=?87). Orius strigicollis was not infected with Spiroplasma (n?=?147). In the early stage of oogenesis (i.e., within the germarium), a large number of bacteria with the typical morphology of Spiroplasma existed, keeping a distance from Wolbachia bacteria. The Spiroplasma population seemed to increase during host development but Wolbachia population did not. 相似文献
88.
89.
Calreticulin (Crt) is a molecular chaperone ubiquitously present in the endoplasmic reticulum. In non-human primates, age-related occurrence of anti-Crt antibody has not been reported. We developed an ELISA assay for an anti-Crt antibody and determined the age-related increase in the levels of anti-Crt antibody in three groups of cynomolgus monkeys: juvenile (1.5 yr), young adults (5-10 yr) and aged adults (20-34 yr). Mean ± SD auto-antibody levels at 450 nm in juvenile, young adults and aged groups were 0.23 ± 0.18, 0.30 ± 0.28, and 0.55 ± 0.33, respectively. Statistically significant differences were noted in the autoantibody levels to Crt among the aged group and juvenile or young adults. This is the first report to demonstrate the expression of anti-Crt autoantibody in aged monkeys and indicates that cynomologous monkeys may serve as an appropriate nonhuman primate model for studies of age-related alteration of immune function in elderly humans. Though preliminary, this finding merits further investigation to determine the relationship between immunosenescence and expression of antibodies to Crt. 相似文献
90.