Search results for " Recombination"
showing 10 items of 86 documents
Artesunate derived from traditional Chinese medicine induces DNA damage and repair.
2008
Abstract Artesunate is a semisynthetic derivative from artemisinin, a natural product from the Chinese herb Artemisia annua L. It exerts antimalarial activity, and, additionally, artemisinin and its derivatives are active against cancer cells. The active moiety is an endoperoxide bridge. Its cleavage leads to the formation of reactive oxygen species and carbon-centered radicals. These highly reactive molecules target several proteins in Plasmodia, which is thought to result in killing of the microorganism. DNA damage induced by artemisinins has not yet been described. Here, we show that artesunate induces apoptosis and necrosis. It also induces DNA breakage in a dose-dependent manner as sho…
Artesunate induces oxidative DNA damage, sustained DNA double-strand breaks, and the ATM/ATR damage response in cancer cells.
2011
Abstract Artesunate, the active agent from Artemisia annua L. used in the traditional Chinese medicine, is being applied as a first-line drug for malaria treatment, and trials are ongoing that include this drug in cancer therapy. Despite increasing interest in its therapeutic application, the mode of cell killing provoked by artesunate in human cells is unknown. Here, we show that artesunate is a powerful inducer of oxidative DNA damage, giving rise to formamidopyrimidine DNA glycosylase–sensitive sites and the formation of 8-oxoguanine and 1,N6-ethenoadenine. Oxidative DNA damage was induced in LN-229 human glioblastoma cells dose dependently and was paralleled by cell death executed by ap…
Rad51 and BRCA2 - New Molecular Targets for Sensitizing Glioma Cells to Alkylating Anticancer Drugs
2011
First line chemotherapeutics for brain tumors (malignant gliomas) are alkylating agents such as temozolomide and nimustine. Despite growing knowledge of how these agents work, patients suffering from this malignancy still face a dismal prognosis. Alkylating agents target DNA, forming the killing lesion O(6)-alkylguanine, which is converted into DNA double-strand breaks (DSBs) that trigger apoptosis. Here we assessed whether inhibiting repair of DSBs by homologous recombination (HR) or non-homologous end joining (NHEJ) is a reasonable strategy for sensitizing glioma cells to alkylating agents. For down-regulation of HR in glioma cells, we used an interference RNA (iRNA) approach targeting Ra…
Exciton recombination dynamics in InAs∕InP self-assembled quantum wires
2005
In this work we investigate the exciton recombination dynamics in InAs∕InP semiconductor self-assembled quantum wires, by means of continuous wave and time resolved photoluminescence. The continuous wave photoluminescence results seem to indicate that the temperature quenching of the emission band seems to be more probably due to unipolar thermal escape of electrons towards the InP barrier. On the other hand, the analysis of time resolved photoluminescence reveals that the temperature dependence of the radiative and nonradiative recombination times is mainly determined by the dynamics of excitons localized by disorder (high energy tail of the PL band) and strongly localized (low energy tail…
Deinococcus radiodurans' SRA-HNH domain containing protein Shp (Dr1533) is involved in faithful genome inheritance maintenance following DNA damage
2018
WOS:000452343100012; International audience; Background: Deinococcus radiodurans R1 (DR) survives conditions of extreme desiccation, irradiation and exposure to genotoxic chemicals, due to efficient DNA breaks repair, also through Mn2+ protection of DNA repair enzymes. Methods: Possible annotated domains of the DR1533 locus protein (Shp) were searched by bioinformatic analysis. The gene was cloned and expressed as fusion protein. Band-shift assays of Shp or the SRA and HNH domains were performed on oligonucleotides, genomic DNA from E. coif and DR. slip knock-out mutant was generated by homologous recombination with a kanamycin resistance cassette. Results: DR1533 contains an N-terminal SRA…
Characterization of a cryogenic ion guide at IGISOL
2012
A small volume cryogenic ion guide has been characterized at the IGISOL facility, Jyvaskyla, as a prototype to verify whether there are any major obstacles to the use of high-density cryogenic helium gas for the stopping and extraction of high-energy ions from a large volume cryogenic ion catcher. The expected temperature scaling of the mass flow through the ion guide has been confirmed, showing that for the same helium density, the differential pumping requirements are less stringent for cryogenic operation. At 90 K a clear reduction in the mass-analyzed impurities is achieved, although lower temperatures are required to freeze out oxygen and nitrogen. This is supported by the reduction in…
Investigating the origin of parthenogenesis and ploidy level in Dahlica fennicella (Lepidoptera: Psychidae)
2013
The theories for the predominance of sexual reproduction predict that parthenogens should have no long-term evolutionary potential due to the lack of genetic recombination, despite short term advantages. Although parthenogenesis is rare among high order animals, true parthenogens can be found in various taxa. The intriguing question of the proliferation and persistence of parthenogenetic species needs investigation. An ideal species for such research is a parthenogenetic mont Dahlica fennicella that appears to be as equally successful as other coexisting sexual species. We investigated whether high ploidy level of D. fennnicella is due to hybridization between closely related sexual species…
Impedance of space-charge-limited currents in organic light-emitting diodes with double injection and strong recombination
2006
The impedance model for a one-carrier space-charge-limited (SCL) current has been applied to explain some experimental features of double carrier organic light-emitting diodes. We report the analytical model of impedance of bipolar drift transport in SCL regime in the limit of infinite recombination. In this limit the ac impedance function is identical to that of a single carrier device, with a transit time modified by the sum of mobilities for electrons and holes, μn+μp. The static capacitance C(ω→0) is a factor of ¾ lower than the geometric capacitance, as observed for single carrier devices, but it is shifted to higher frequencies. It follows that impedance measurements in the dual-carri…
Acoustic manipulation of electron-hole pairs in GaAs at room temperature
2004
We demonstrate the optically detected long-range (>100 μm) ambipolar transport of photogenerated electrons and holes at room temperature by surface acoustic waves (SAWs) in (In,Ga)As-based quantum well structures coupled to an optical microcavity. We also show the control of the propagation direction of the carriers by a switch composed of orthogonal SAW beams, which can be used as a basic control gate for information processing based on ambipolar transport.
Analysis of the ORF2 of human astroviruses reveals lineage diversification, recombination and rearrangement and provides the basis for a novel sub-cl…
2014
Canonical human astroviruses (HAstVs) are important enteric pathogens that can be classified genetically and antigenically into eight types. Sequence analysis of small diagnostic regions at either the 5' or 3' end of ORF2 (capsid precursor) is a good proxy for prediction of HAstV types and for distinction of intratypic genetic lineages (subtypes), although lineage diversification/classification has not been investigated systematically. Upon sequence and phylogenetic analysis of the full-length ORF2 of 86 HAstV strains selected from the databases, a detailed classification of HAstVs into lineages was established. Three main lineages could be defined in HAstV-1, four in HAstV-2, two in HAstV-…