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Search Results: 1 - 10 of 1089 matches for " Nikolai Windbichler "
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Targeting the X Chromosome during Spermatogenesis Induces Y Chromosome Transmission Ratio Distortion and Early Dominant Embryo Lethality in Anopheles gambiae
Nikolai Windbichler equal contributor,Philippos Aris Papathanos equal contributor,Andrea Crisanti
PLOS Genetics , 2008, DOI: 10.1371/journal.pgen.1000291
Abstract: We have exploited the high selectivity of the homing endonuclease I-PpoI for the X-linked Anopheles gambiae 28S ribosomal genes to selectively target X chromosome carrying spermatozoa. Our data demonstrated that in heterozygous males, the expression of I-PpoI in the testes induced a strong bias toward Y chromosome–carrying spermatozoa. Notably, these male mosquitoes also induced complete early dominant embryo lethality in crosses with wild-type females. Morphological and molecular data indicated that all spermatozoa, irrespectively of the inheritance of the transgene, carried a substantial amount of I-PpoI protein that could attack the maternally inherited chromosome X of the embryo. Besides the obvious implications for implementing vector control measures, our data demonstrated the feasibility of generating synthetic sex distorters and revealed the intriguing possibility of manipulating maternally inherited genes using wild-type sperm cells carrying engineered endonucleases.
The vasa regulatory region mediates germline expression and maternal transmission of proteins in the malaria mosquito Anopheles gambiae: a versatile tool for genetic control strategies
Philippos A Papathanos, Nikolai Windbichler, Miriam Menichelli, Austin Burt, Andrea Crisanti
BMC Molecular Biology , 2009, DOI: 10.1186/1471-2199-10-65
Abstract: We have identified the Anopheles gambiae vasa-like gene and found its expression to be specifically localized to both the male and female gonads in adult mosquitoes. We have functionally characterised using transgenic reporter lines the regulatory regions required for driving transgene expression in a pattern mirroring that of the endogenous vasa locus. Two reporter constructs indicate the existence of distinct vasa regulatory elements within the 5' untranslated regions responsible not only for the spatial and temporal but also for the sex specific germline expression. vasa driven eGFP expression in the ovary of heterozygous mosquitoes resulted in the progressive accumulation of maternal protein and transcript in developing oocytes that were then detectable in all embryos and neonatal larvae.We have characterized the vasa regulatory regions that are not only suited to drive transgenes in the early germline of both sexes but could also be utilized to manipulate the zygotic genome of developing embryos via maternal deposition of active molecules. We have used computational models to show that a homing endonuclease-based gene drive system can function in the presence of maternal deposition and describe a novel non-invasive control strategy based on early vasa driven homing endonuclease expression.Mosquito species of the Anopheles gambiae complex are the major vectors of the human malaria parasite Plasmodium falciparum and pose an enormous burden on human health and economies. Every year about 300 million people are infected by Plasmodium parasites and over a million children die as consequence of malaria infection[1]. While many insect pests species have long been successfully targeted by population control measures such as insecticides, for others, including A. gambiae, many countries lack the resources and the logistics to successfully implement these measures over prolonged periods of time. Alternative vector control strategies that are affordable, easy to implement
Demasculinization of the Anopheles gambiae X chromosome
Kalle Magnusson, Gareth J Lycett, Antonio M Mendes, Amy Lynd, Philippos-Aris Papathanos, Andrea Crisanti, Nikolai Windbichler
BMC Evolutionary Biology , 2012, DOI: 10.1186/1471-2148-12-69
Abstract: We performed a meta-analysis of sex-biased gene expression in Anopheles gambiae which provides evidence for a general underrepresentation of male-biased genes on the X-chromosome that increased in significance with the observed degree of sex-bias. A phylogenomic comparison between Drosophila melanogaster, Aedes aegypti and Culex quinquefasciatus also indicates that the Anopheles X chromosome strongly disfavours the evolutionary conservation of male-biased expression and that novel male-biased genes are more likely to arise on autosomes. Finally, we demonstrate experimentally that transgenes situated on the Anopheles gambiae X chromosome are transcriptionally silenced in the male germline.The data presented here support the hypothesis that the observed demasculinization of the Anopheles X chromosome is driven by X-chromosome inactivation in the male germline and by sexual antagonism. The demasculinization appears to be the consequence of a loss of male-biased expression, rather than a failure in the establishment or the extinction of male-biased genes.
Transcription Regulation of Sex-Biased Genes during Ontogeny in the Malaria Vector Anopheles gambiae
Kalle Magnusson,Antonio M. Mendes,Nikolai Windbichler,Philippos-Aris Papathanos,Tony Nolan,Tania Dottorini,Ermanno Rizzi,George K. Christophides,Andrea Crisanti
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0021572
Abstract: In Anopheles gambiae, sex-regulated genes are responsible for controlling gender dimorphism and are therefore crucial in determining the ability of female mosquitoes to transmit human malaria. The identification and functional characterization of these genes will shed light on the sexual development and maturation of mosquitoes and provide useful targets for genetic control measures aimed at reducing mosquito fertility and/or distorting the sex ratio.
Binding of Hoechst with nucleic acids using fluorescence spectroscopy  [PDF]
Nikolai Vekshin
Journal of Biophysical Chemistry (JBPC) , 2011, DOI: 10.4236/jbpc.2011.24052
Abstract: It has been shown that polarity of environment around Hoechst 33342 is almost unchanged while sorption of this fluorescent dye on a surface of the hairpin oligonucleotide HP1, t-RNA and DNA. At small concentrations, this dye, adsorbed on the surface of DNA, RNA or HP1, does not show any specificity to certain nucleotides. In the case of unwound sites of DNA or HP1, it can bind inside, but without the intercalation stacking with nucleotides. The energy transfer from nucleotide chromophores to Hoechst is absent due to their remoteness and also “bad” (non-stacking) orientation. The mutual fluorescence quenching of Hoechst by actinomycin D (AMD) and, vice versa, of 7-amino-actinomycin D (7AAMD) by Hoechst in DNA and HP1 is observed. It is due to dynamic deactivation and mutual replacing in binding sites.
Structures of Confinements as an Empirical Property of Consciousness and a Fundamental Property in Physics  [PDF]
Nikolai Lyng
Open Journal of Philosophy (OJPP) , 2016, DOI: 10.4236/ojpp.2016.61012
Abstract: Our consciousness is confined to experience our own thoughts. By subjectively investigating associations between conscious experiences from different senses, it can be shown how confinement must be an existing property relating to smaller parts of our conscious experiences as well. In this article, it is investigated how entities confining other entities may serve as fundamental building blocks of physics and consciousness. The model evolves by changing the structure of confinements. It turns out that classical mechanics, relativity, quantum mechanics, non-locality, and a solution to the measurement problem in quantum mechanics follow from the definition of this model. The model also clarifies how different conscious experiences can be determined by different physical states, which is related to the hard problem of consciousness.
Calculated and Experimental Regularities of Cloud Microstructure Formation and Evolution  [PDF]
Nikolai Romanov, Vasiliy Erankov
Atmospheric and Climate Sciences (ACS) , 2013, DOI: 10.4236/acs.2013.33032

Based on the model of regular condensation it was found that at low concentrations of CN (LC mode) at a height of about 10 m from the condensation level narrow spectra of cloud drop are formed. Their dispersion quickly decreases with increasing height. For high concentrations (HC mode) broad spectra are formed immediately due to the absence of separation into growing drops and CN covered with water. The process of spectra evolution is conducted at a constant height results, in all the cases, in the appearance of asymptotic spectra with a relative width rb 0.215. To approximate these calculated asymptotic spectra, the modified gamma-distribution with the fixed parameter α = 3 and a variable parameter γ are most suitable. For the intermediate spectra applicable are the simpler mirror-transformed known distributions. The comparison of the above distributions with the experimental spectra of a fog artificially formed in the Big Aerosol Chamber (BAC) of RPA “Typhoon” and the spectra of the morning fog and super cooled stratiform clouds demonstrated their good agreement. The phenomenon of multimodal spectra formation at a sharp rise of stratiform clouds with the velocity more than 0.1 - 0.3 m/s was theoretically shown and experimentally confirmed. The effect of CN high concentrations, evolution processes and sharp fluctuations of vertical velocities on the formation of cloud spectra observed in nature is discussed.

Anomalous Quark Chromomagnetic Moment and Single-Spin Asymmetries
Nikolai Kochelev,Nikolai Korchagin
Physics , 2013, DOI: 10.1016/j.physletb.2014.01.003
Abstract: We discuss a nonperturbative mechanism for the single-spin asymmetries (SSA) in the strong interaction. This mechanism is based on the existence of a large anomalous quark chromomagnetic moment (AQCM) induced by the nontrivial topological structure of QCD vacuum. Our estimations within the instanton liquid model for QCD vacuum show that AQCM generates very large SSA on the quark level. Therefore, this mechanism can be responsible for the anomalously large SSA observed in different high energy reactions with hadrons.
Changes of Reef Community near Ku Lao Cham Islands (South China Sea) after Sangshen Typhoon  [PDF]
Yuri Ya. Latypov, Nikolai Selin
American Journal of Climate Change (AJCC) , 2012, DOI: 10.4236/ajcc.2012.11004
Abstract: Coral reefs of Ku Lao Cham Islands in the Central Vietnam were studied over a quarter of a century. It was established that the reefs of these Islands were lost after the Sangshen typhoon and a heavy flood, which happened in 2006. As a result of these natural phenomena a significant part of coral populations was physically destroyed, and a powerful export of clay substances from the nearest Vietnamese coast and from the Bung River, flowing into the sea opposite the Islands, causing abundant sedimentation and death of almost all the remaining scleractinian corals. At present, where formerly there were coral reefs, now there is algal-alcyonarian stage of succession of reef communities. This is typical, as a rule, for restoration of reefs after a destructive typhoon effect.
Trypanosoma cruzi, cancer and the Cold War
Krementsov, Nikolai;
História, Ciências, Saúde-Manguinhos , 2009, DOI: 10.1590/S0104-59702009000500005
Abstract: in the summer of 1946, the international community of cancer researchers was inspired by the announcement that two soviet scientists, nina kliueva and grigorii roskin, had discovered anticancer properties in culture extracts made from the south american protozoan, trypanosoma cruzi, and had produced a preparation - named after its discoverers kr - which showed clear therapeutic effects on cancer patients. research teams from various countries enthusiastically pursued the promising new line of investigation. the story of the rise and fall of interest in the anticancer properties of t. cruzi in different countries suggests that during the second half of the twentieth century, the cold war competition between the superpowers played an important role in shaping the research agendas of cancer studies.
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