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91.
Protozoa in the phylum Apicomplexa are a large group of obligate intracellular parasites. Toxoplasma gondii and other apicomplexan parasites, such as Plasmodium falciparum, cause diseases by reiterating their lytic cycle, comprising host cell invasion, parasite replication, and parasite egress. The successful completion of the lytic cycle requires that the parasite senses changes in its environment and switches between the non-motile (for intracellular replication) and motile (for invasion and egress) states appropriately. Although the signaling pathway that regulates the motile state switch is critical to the pathogenesis of the diseases caused by these parasites, it is not well understood. Here we report a previously unknown mechanism of regulating the motility activation in Toxoplasma, mediated by a protein lysine methyltransferase, AKMT (for Apical complex lysine (K) methyltransferase). AKMT depletion greatly inhibits activation of motility, compromises parasite invasion and egress, and thus severely impairs the lytic cycle. Interestingly, AKMT redistributes from the apical complex to the parasite body rapidly in the presence of egress-stimulating signals that increase [Ca2+] in the parasite cytoplasm, suggesting that AKMT regulation of parasite motility might be accomplished by the precise temporal control of its localization in response to environmental changes. 相似文献
92.
Inoue M Sawada N Shimazu T Yamaji T Iwasaki M Sasazuki S Tsugane S;Japan Public Health Center-based Prospective Study Group 《Cancer epidemiology》2011,35(3):250-253
The recent tendency of Japanese towards greater acceptance of being informed that they have cancer, along with the growing understanding and use of informed consent, appears to have improved the accuracy of self-reported cancer. To clarify the recent validity of self-reports, we measured the sensitivity and positive predictive value of self-reported cancer among a Japanese population. Using a 10-year follow-up questionnaire conducted in 2000-2004 and the cancer registry of the JPHC Study cohort (n=93,680), we calculated the sensitivity and positive predictive value of self-reported cancer diagnoses over 10 years. Sensitivity and positive predictive value of total self-reported cancer diagnoses were 53% and 60%, respectively, but varied by site, at 62% and 52% for stomach, 38% and 47% for colorectum, 57% and 46% for lung, 34% and 31% for liver, 82% and 58% for breast, and 59% and 22% for uterus, respectively. Sensitivity was considerably improved from that in the previous report (36%), which tested for 1990-1995, but was still not considered satisfactory. Self-reported diagnoses of cancer do not provide sufficient accuracy for the detection and classification of incident cancers. Our findings may be extrapolated to other Japanese populations. 相似文献
93.
A number of social insect species have recently been shown to have genetically influenced caste determination (GCD), challenging the conventional view that caste determination should be strictly environmental. To date, GCD has been found in phylogenetically isolated species; examples of GCD being present in multiple species of a genus are lacking. Through crossing experiments of neotenic (juvenile) reproductives, we have recently provided the first evidence for a royal versus worker GCD in the termite Reticulitermes speratus. To elucidate whether this system is more widespread, we performed crossing experiments using three additional Reticulitermes species. Offspring caste and sex ratios were found to be highly similar to those found previously in R. speratus, raising the possibility that GCD was present in an ancestral lineage of Reticulitermes, and subsequently maintained throughout several episodes of speciation. 相似文献
94.
Background
Our previous study has shown that prenatal exposure to X-ray irradiation causes cerebral hypo-perfusion during the postnatal development of central nervous system (CNS). However, the source of the hypo-perfusion and its impact on the CNS development remains unclear. The present study developed an automatic analysis method to determine the mean red blood cell (RBC) speed through single microvessels imaged with two-photon microscopy in the cerebral cortex of rats prenatally exposed to X-ray irradiation (1.5 Gy).Methodology/Principal Findings
We obtained a mean RBC speed (0.9±0.6 mm/sec) that ranged from 0.2 to 4.4 mm/sec from 121 vessels in the radiation-exposed rats, which was about 40% lower than that of normal rats that were not exposed. These results were then compared with the conventional method for monitoring microvascular perfusion using the arteriovenous transit time (AVTT) determined by tracking fluorescent markers. A significant increase in the AVTT was observed in the exposed rats (1.9±0.6 sec) as compared to the age-matched non-exposed rats (1.2±0.3 sec). The results indicate that parenchyma capillary blood velocity in the exposed rats was approximately 37% lower than in non-exposed rats.Conclusions/Significance
The algorithm presented is simple and robust relative to monitoring individual RBC speeds, which is superior in terms of noise tolerance and computation time. The demonstrative results show that the method developed in this study for determining the mean RBC speed in the spatial frequency domain was consistent with the conventional transit time method. 相似文献95.
96.
Mikamo E Tanaka C Kanno T Akiyama H Jung G Tanaka H Kawai T 《Journal of structural biology》2005,151(1):106-110
The native polysomes of Saccharomyces cerevisiae were visualized in liquid solution by atomic force microscopy without external contrasting, such as shadowing and negative staining. This study showed native polysomes as lined particle with a height of ca. 27 nm, which is agreement with the height of 80S ribosomes in previous study. We found a small subparticle, located in a ring-shape or at the end of a linear structure, and visualized mRNA chains between adjacent ribosomes. Although the structures of polysomes have been studied for decades, it has remained difficult to visualize the native three-dimensional form. By the observation in liquid solution, we temporarily stopped the translation using an antibiotic to presenting the native three-dimensional structure and function of the polysomes. Our results provide not only new findings on native eukaryotic polysomes, but also great potential to visualize the influence of various environmental conditions on polysomes. 相似文献
97.
Zaochang?LiuEmail author Byong-Jin?Park Akira?Kanno Toshiaki?Kameya 《Molecular breeding : new strategies in plant improvement》2005,16(3):189-197
An efficient gene transfer system without tissue culture steps was developed for kidney bean by using sonication and vacuum
infiltration assisted, Agrobacterium-mediated transformation. Transgenic kidney bean with a group 3 lea (late embryogenesis abundant) protein gene from Brassica napus was produced through this approach. Among 18 combinations of transformation methods, Agrobacterium-mediated transformation combined with 5 min sonication and 5 min vacuum infiltration turned to be optimal, resulting in the
highest transformation efficiency. Transgenic kidney bean plants demonstrated enhanced growth ability under salt and water
deficit stress conditions. The increased tolerance was also reflected by delayed development of damage symptoms caused by
drought stress. Transgenic lines with high level of lea gene expression showed higher stress tolerance than lines with lower expression level. Stress tolerance of transgenic kidney
bean correlated much better with lea gene expression levels than with gene integration results. There is no prior report on the production of transgenic kidney
bean using both ultrasonic and vacuum infiltration assisted, Agrobacterium-mediated transformation. 相似文献
98.
Efficient cleavage of RNA, enhanced cellular uptake, and controlled intracellular localization of conjugate DNAzymes 总被引:3,自引:0,他引:3
Kubo T Takamori K Kanno K Bakalova R Rumiana B Ohba H Matsukisono M Akebiyama Y Fujii M 《Bioorganic & medicinal chemistry letters》2005,15(1):167-170
Conjugate DNAzymes with polyamines and peptides were successfully prepared by solid phase fragment condensation (SPFC) and showed up to 4.2 times higher catalytic efficiency (k(cat)/K(m)) and enhanced tolerance against DNase 1digestion. To be pointed out, intracellular localization of DNAzymes could be controlled by conjugated with naturally occurring signal peptides responsible for nuclear cytoplasmic transport of proteins. 相似文献
99.
Suzuki H Tamamura R Yajima S Kanno M Suguro M 《Bioscience, biotechnology, and biochemistry》2005,69(5):952-956
The sarcosine oxidase gene and nearby genes from Corynebacterium sp. U-96 were determined. The genes for serine hydroxymethyltransferase, the beta, delta, alpha, and gamma subunits of sarcosine oxidase, serine dehydratase, and 10-formyltetrahydrofolate hydrolase are arranged in this order. This suggests that the bacteria contain a cluster of genes for the catabolism of sarcosine to pyruvate. The possibility that the gene cluster is a merit for the cellular energy demands of the bacteria is discussed. Functional expression of sarcosine oxidase in Escherichia coli was accomplished, but the beta subunit and the betadelta complex were expressed at a low level as a soluble protein. 相似文献
100.
DRD1 is a SNF2-like protein previously identified in a screen for mutants defective in RNA-directed DNA methylation of a seed promoter in Arabidopsis. Although the initial study established a role for DRD1 in RNA-directed DNA methylation, it did not address whether DRD1 is needed for de novo or maintenance methylation, or whether it is required for methylation of other target sequences. We show here that DRD1 is essential for RNA-directed de novo methylation and acts on different target promoters. In addition, an unanticipated role for DRD1 in erasure of CG methylation was shown when investigating maintenance methylation after segregating away the silencing trigger. DRD1 is unique among known SNF2-like proteins in facilitating not only de novo methylation of target sequences in response to RNA signals, but also loss of methylation when the silencing inducer is withdrawn. The opposing roles of DRD1 could contribute to the dynamic regulation of DNA methylation. 相似文献