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101.
Although there have been a few reports that the HIV-1 genome can be selectively integrated into the genomic DNA of cultured host cell, the biochemistry of integration selectivity has not been fully understood. We modified the in vitro integration reaction protocol and developed a reaction system with higher efficiency. We used a substrate repeat, 5'-(GTCCCTTCCCAGT)(n)(ACTGGGAAGGGAC)(n)-3', and a modified sequence DNA ligated into a circular plasmid. CAGT and ACTG (shown in italics in the above sequence) in the repeat units originated from the HIV-1 proviral genome ends. Following the incubation of the HIV-1 genome end cDNA and recombinant integrase for the formation of the pre-integration (PI) complex, substrate DNA was reacted with this complex. It was confirmed that the integration selectively occurred in the middle segment of the repeat sequence. In addition, integration frequency and selectivity were positively correlated with repeat number n. On the other hand, both frequency and selectivity decreased markedly when using sequences with deletion of CAGT in the middle position of the original target sequence. Moreover, on incubation with the deleted DNAs and original sequence, the integration efficiency and selectivity for the original target sequence were significantly reduced, which indicated interference effects by the deleted sequence DNAs. Efficiency and selectivity were also found to vary discontinuously with changes in manganese dichloride concentration in the reaction buffer, probably due to its influence on the secondary structure of substrate DNA. Finally, integrase was found to form oligomers on the binding site and substrate DNA formed a loop-like structure. In conclusion, there is a considerable selectivity in HIV-integration into the specified sequence; however, similar DNA sequences can interfere with the integration process, and it is therefore difficult for in vivo integration to occur selectively in the actual host genome DNA. 相似文献
102.
Abe S Chamnan C Miyamoto K Minamino Y Nouda M 《Marine biotechnology (New York, N.Y.)》2004,6(6):527-540
103.
The freshwater goby Rhinogobius is the most abundant fish in the shore area of Lake Biwa, Japan. Recently, it has been reported that two morphs of Rhinogobius inhabit this lake. In this study, genetic variations in Rhinogobius sp. OR (Orange-type) and Rhinogobius sp. BW (Biwa-type) in the Lake Biwa water system have been investigated using polymerase chain reaction-based restriction fragment length polymorphism (PCR-RFLP) analysis of mitochondrial DNA, including the variable D-loop region. Samples of Rhinogobius sp. OR were collected from the middle sites of three rivers, two outlets, and two lakeshore sites, whereas samples of Rhinogobius sp. BW were taken from two lakeshore sites. Rhinogobius sp. OR and Rhinogobius sp. BW did not share any haplotypes, suggesting that PCR-RFLP analysis is effective for distinguishing between these species of goby. The haplotype diversity of Rhinogobius sp. OR (0.214–0.543) was lower than that of Rhinogobius sp. BW (0.543–0.682). There were no significant differences in haplotype frequencies between Rhinogobius sp. BW groups from the two localities. In addition, haplotype frequencies in Rhinogobius sp. OR did not differ significantly among samples from the middle sites of rivers, the outlets, and the shores. These results indicate that in Rhinogobius sp. OR there is frequent gene flow among fish inhabiting different sites, and that this species of goby consists of a single population throughout the Lake Biwa water system. 相似文献
104.
105.
Recent advances in the use of summed probability distribution (SPD) of calibrated 14C dates have opened new possibilities for studying prehistoric demography. The degree of correlation between climate change and population dynamics can now be accurately quantified, and divergences in the demographic history of distinct geographic areas can be statistically assessed. Here we contribute to this research agenda by reconstructing the prehistoric population change of Jomon hunter-gatherers between 7,000 and 3,000 cal BP. We collected 1,433 14C dates from three different regions in Eastern Japan (Kanto, Aomori and Hokkaido) and established that the observed fluctuations in the SPDs were statistically significant. We also introduced a new non-parametric permutation test for comparing multiple sets of SPDs that highlights point of divergences in the population history of different geographic regions. Our analyses indicate a general rise-and-fall pattern shared by the three regions but also some key regional differences during the 6th millennium cal BP. The results confirm some of the patterns suggested by previous archaeological studies based on house and site counts but offer statistical significance and an absolute chronological framework that will enable future studies aiming to establish potential correlation with climatic changes. 相似文献
106.
Maternal care in the red-headed spruce web-spinning sawfly,Cephalcia isshikii (Hymenoptera: Pamphiliidae) 总被引:1,自引:0,他引:1
We describe oviposition and maternal behavior in the sawfly Cephalcia isshikiiand examine the adaptive significance of this behavior. Females deposited eggs in a single but loose cluster on needles of terminal twigs of spruces, Piceaspp., and remained with the eggs usually on the underside of the twig facing toward the tip. The female attended her eggs until death without taking food but did not follow the first-instar larvae that moved from natal needles even if she survived until then. When the female was disturbed, she usually moved toward the source and attempted to bite it. Though at much lower frequencies, this aggressive behavior was also observed in gravid females and even in males. Field observations and female removal experiments indicated that the female enhanced the survival of the eggs through the reduction of arthropod prédation. 相似文献
107.
Y Hasegawa Y Hayabuchi I Namba T Watanabe K Kato R Ijiri Y Tanaka K Sekido H Kigasawa M Hara 《Acta cytologica》2001,45(6):1037-1042
108.
To understand the incompatibility between two related plasmids, both of which replicate in an autonomous state under a common control mechanism, we have developed a model that assumes a random choice mechanism for replication of plasmid copies and their random assortment into daughter cells upon cell division. Segregation kinetics by this model is analyzed mathematically and the number of generations required for segregation is calculated as a function of plasmid copy number per cell. The results obtained offer enough quantitative data to make our model reasonably realistic. 相似文献
109.
Tomoaki Murotsu Hiroshi Tanaka Masami Imaji Hideo Koga Kenichi Matsubara Tadao Horiuchi 《Molecular & general genetics : MGG》1977,157(2):139-147
Summary In order to study the mode of action of the tof gene product, which is an autorepressor of the bacteriophage and plasmid dv, we have purified a DNA-binding protein which is specifically produced in bacteria carrying dv. This protein possesses characteristics expected for the product of the tof gene, since it is produced under conditions where cI-repressor is not made, and since it binds to oL and oR operators on the phage genome. The molecular weight of the native protein is 16,000–17,000 daltons, and the monomeric molecular weight as measured by gel electrophoresis in the presence of sodium dodecyl sulfate is about 10,000 daltons. Denaturation and renaturation experiments demonstrated that the native protein is a dimer of 10,000-dalton monomers. The DNA-specific binding protein is not produced in cells carrying i
21dv or 80dv. 相似文献
110.
Yoshinori Harada Ping Dai Yoshihisa Yamaoka Mitsugu Ogawa Hideo Tanaka Kazuto Nosaka Kenichi Akaji Tetsuro Takamatsu 《Histochemistry and cell biology》2009,132(1):39-46
Most molecular imaging technologies require exogenous probes and may have some influence on the intracellular dynamics of
target molecules. In contrast, Raman scattering light measurement can identify biomolecules in their innate state without
application of staining methods. Our aim was to analyze intracellular dynamics of topoisomerase I inhibitor, CPT-11, by using
slit-scanning confocal Raman microscopy, which can take Raman images with high temporal and spatial resolution. We could acquire
images of the intracellular distribution of CPT-11 and its metabolite SN-38 within several minutes without use of any exogenous
tags. Change of subcellular drug localization after treatment could be assessed by Raman imaging. We also showed intracellular
conversion from CPT-11 to SN-38 using Raman spectra. The study shows the feasibility of using slit-scanning confocal Raman
microscopy for the non-labeling evaluation of the intracellular dynamics of CPT-11 with high temporal and spatial resolution.
We conclude that Raman spectromicroscopic imaging is useful for pharmacokinetic studies of anticancer drugs in living cells.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献