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Search Results: 1 - 10 of 1502 matches for " Marius Liesch "
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Parallel Evolution of a Type IV Secretion System in Radiating Lineages of the Host-Restricted Bacterial Pathogen Bartonella
Philipp Engel,Walter Salzburger,Marius Liesch,Chao-Chin Chang,Soichi Maruyama,Christa Lanz,Alexandra Calteau,Aurélie Lajus,Claudine Médigue,Stephan C. Schuster,Christoph Dehio
PLOS Genetics , 2011, DOI: 10.1371/journal.pgen.1001296
Abstract: Adaptive radiation is the rapid origination of multiple species from a single ancestor as the result of concurrent adaptation to disparate environments. This fundamental evolutionary process is considered to be responsible for the genesis of a great portion of the diversity of life. Bacteria have evolved enormous biological diversity by exploiting an exceptional range of environments, yet diversification of bacteria via adaptive radiation has been documented in a few cases only and the underlying molecular mechanisms are largely unknown. Here we show a compelling example of adaptive radiation in pathogenic bacteria and reveal their genetic basis. Our evolutionary genomic analyses of the α-proteobacterial genus Bartonella uncover two parallel adaptive radiations within these host-restricted mammalian pathogens. We identify a horizontally-acquired protein secretion system, which has evolved to target specific bacterial effector proteins into host cells as the evolutionary key innovation triggering these parallel adaptive radiations. We show that the functional versatility and adaptive potential of the VirB type IV secretion system (T4SS), and thereby translocated Bartonella effector proteins (Beps), evolved in parallel in the two lineages prior to their radiations. Independent chromosomal fixation of the virB operon and consecutive rounds of lineage-specific bep gene duplications followed by their functional diversification characterize these parallel evolutionary trajectories. Whereas most Beps maintained their ancestral domain constitution, strikingly, a novel type of effector protein emerged convergently in both lineages. This resulted in similar arrays of host cell-targeted effector proteins in the two lineages of Bartonella as the basis of their independent radiation. The parallel molecular evolution of the VirB/Bep system displays a striking example of a key innovation involved in independent adaptive processes and the emergence of bacterial pathogens. Furthermore, our study highlights the remarkable evolvability of T4SSs and their effector proteins, explaining their broad application in bacterial interactions with the environment.
Functional and Genetic Characterization of Neuropeptide Y-Like Receptors in Aedes aegypti
Jeff Liesch,Lindsay L. Bellani,Leslie B. Vosshall
PLOS Neglected Tropical Diseases , 2013, DOI: 10.1371/journal.pntd.0002486
Abstract: Background Female Aedes aegypti mosquitoes are the principal vector for dengue fever, causing 50–100 million infections per year, transmitted between human and mosquito by blood feeding. Ae. aegypti host-seeking behavior is known to be inhibited for three days following a blood meal by a hemolymph-borne humoral factor. Head Peptide-I is a candidate peptide mediating this suppression, but the mechanism by which this peptide alters mosquito behavior and the receptor through which it signals are unknown. Methodology/Principal Findings Head Peptide-I shows sequence similarity to short Neuropeptide-F peptides (sNPFs) that have been implicated in feeding behaviors and are known to signal through Neuropeptide Y (NPY)-Like Receptors (NPYLRs). We identified eight NPYLRs in the Ae. aegypti genome and screened each in a cell-based calcium imaging assay for sensitivity against a panel of peptides. Four of the Ae. aegypti NPYLRs responded to one or more peptide ligands, but only NYPLR1 responded to Head Peptide-I as well as sNPFs. Two NPYLR1 homologues identified in the genome of the Lyme disease vector, Ixodes scapularis, were also sensitive to Head Peptide-I. Injection of synthetic Head Peptide-I and sNPF-3 inhibited host-seeking behavior in non-blood-fed female mosquitoes, whereas control injections of buffer or inactive Head Peptide-I [Cys10] had no effect. To ask if NPYLR1 is necessary for blood-feeding-induced host-seeking inhibition, we used zinc-finger nucleases to generate five independent npylr1 null mutant strains and tested them for behavioral abnormalities. npylr1 mutants displayed normal behavior in locomotion, egg laying, sugar feeding, blood feeding, host seeking, and inhibition of host seeking after a blood meal. Conclusions In this work we deorphanized four Ae. aegypti NPYLRs and identified NPYLR1 as a candidate sNPF receptor that is also sensitive to Head Peptide-I. Yet npylr1 alone is not required for host-seeking inhibition and we conclude that other receptors, additional peptides, or both, regulate this important behavior.
Exploring the Nature of Information Systems Development Methodology: A Synthesized View Based on a Literature Review  [PDF]
Daniela Mihailescu, Marius Mihailescu
Journal of Service Science and Management (JSSM) , 2010, DOI: 10.4236/jssm.2010.32033
Abstract: New Information Systems Development Methodologies (ISDMs) are suggested in the belief that their deployment would be beneficial to consultants in their work. A large number of ISDMs already exist but their value has been questioned and at the same time new methodologies continue to be introduced in an attempt to support and improve the practice of information systems development work. What is not always clear from current studies is that ISDM is a multi-perspective and cross-discipline phenomenon. Although a large amount of knowledge of ISDM is available, different disciplinary interests have resulted in fragmented assessments of it. This paper intends to identify theoretical perspectives applied in the conceptualization of ISDM. A review of the literature on ISDM was conducted and four different theoretical perspectives were identified: 1) system, 2) structure, 3) innovation, and 4) knowledge. While each perspective provides various overarching depictions of ISDM, the synthesized view of ISDM provided in this study reveals the complexities and ambiguities of a multifaceted phenomenon such as ISDM. Suggestions for an alternative conceptualization of ISDM are provided in an attempt to facilitate the investigation of ISDM.
Quantum Tic-Tac-Toe: A Genuine Probabilistic Approach  [PDF]
Marius Nagy, Naya Nagy
Applied Mathematics (AM) , 2012, DOI: 10.4236/am.2012.331243
Abstract: We propose a quantum version of Tic-Tac-Toe which accurately reflects the inherent probabilistic nature of the measurement principle in quantum mechanics. We then formulate a quantum strategy which allows a quantum player to consistently win over a classical player, with a certain probability. This result can be seen as another proof of the superior computational power of a quantum system with respect to a classical one. Our investigation also reveals that the non-determinism and complexity introduced by the principles of quantum mechanics into even the most simple games make brute-force strategies considerably more difficult to implement. Consequently, games in which machines have gained the upper hand over humans may be made fair again by upgrading them to a quantum level.
On a Discrete Version of the Mohr-Mascheroni Theorem  [PDF]
Marius Munteanu, Laura Munteanu
Applied Mathematics (AM) , 2013, DOI: 10.4236/am.2013.411A4002

We introduce a new geometric tool called n-compass and show that the famous theorem of Mascheroni and Mohr remains valid if the traditional compass is replaced by the newly introduced tool.

Rational Equiangular Polygons  [PDF]
Marius Munteanu, Laura Munteanu
Applied Mathematics (AM) , 2013, DOI: 10.4236/am.2013.410197

The main purpose of this note is to investigate equiangular polygons with rational edges. When the number of edges is the power of a prime, we determine simple, necessary and sufficient conditions for the existence of such polygons. As special cases of our investigations, we settle two conjectures involving arithmetic polygons.

Local exact controllability of the diffusion equation in one dimension
Marius Beceanu
Abstract and Applied Analysis , 2003, DOI: 10.1155/s1085337503303033
Abstract: This paper establishes the local exact null controllability of the diffusion equation in one dimension using distributed controls in the case of the Dirichlet boundary value problem. Most of the techniques used in the course of the proof are borrowed from Barbu (2002).
Dani l 2 as satire
Marius Nel
HTS Theological Studies/Teologiese Studies , 2012,
Abstract: Daniel 2 as satire. Readers use intuitive and acquired knowledge about genres in interpreting what they read and hear, underlining the importance of establishing the genre of a specific piece of literature. The genre of the tales in the Book of Daniel (1–6) has been researched over a long period, without leading to a consensus. In this article it is suggested that the genre of the tales in Daniel may be described in terms of satire, used as a means of resistance to foreign political oppression. Especially humor and irony are utilised in the satire to describe Jewish perception of the oppression and oppressor, and to make suggestions for acting in the crisis situation of Antiochus’ suppression of the Jewish religion. This is demonstrated in terms of the tale in Daniel 2, and specifically in the depiction of the indirect characters in the tale – the God of the Jews in Daniel 2, in contrast to the powerlessness of the gods of the mighty heathen king. In this way the true nature of Jewish oppression is pictured in a humorous way when the Babylonian gods are at the mercy of the Jewish God. HTS Teologiese Studies/Theological Studies, 68(1), 2012
“Note on sex for the aged widower”: On André Brink's The Rights of Desire
Marius Crous
Tydskrif vir letterkunde , 2006,
Abstract: This article examines the representation of masculinity in André Brink's novel, The Rights of Desire. Following a remark in Roger Boylan's review of the novel in the Boston Review; this analysis concentrates on Brink's depiction of Afrikaner masculinity and the idea that the character Ruben Olivier represents Brink's conception of the contemporary Afrikaner male, in particular the older Afrikaner male. This is an attempt at determining the validity of Robert Morrell's thesis on masculinity, namely that it is about “men making and remaking masculinity, about challenging hegemonic masculinity and reconstituting it.” The question is whether Brink's portrayal of Afrikaner masculinity confronts the hegemonic and patriarchal power structures associated with Afrikaner men, and whether it provides the reader with a new perspective on Afrikaner masculinity. This article investigates Brink's representation of firstly, the ways Afrikaner men relate to other men, and secondly, the depiction of Afrikaner men in relation to their social class and to women.
Lex et Scientia , 2011,
Abstract: A problem of essence of the state is the one to delimit the discretionary power, respectively the power abuse in the activity of the state’s institutions. The legal behavior of the state’s institutions consists in their right to appreciate them and the power excess generates the violation of a subjective right or of the right that is of legitimate interest to the citizen. The application and nonobservance of the principle of lawfulness in the activities of the state is a complex problem because the exercise of the state’s functions assumes the discretionary powers with which the states authorities are invested, or otherwise said the ‘right of appreciation” of the authorities regarding the moment of adopting the contents of the measures proposed. The discretionary power cannot be opposed to the principle of lawfulness, as a dimension of the state de jure. In this study we propose to analyze the concept of discretionary power, respectively the power excess, having as a guidance the legislation, jurisprudence and doctrine in the matter. At the same time we would like to identify the most important criterions that will allow the user, regardless that he is or not an administrator, a public clerk or a judge, to delimit the legal behavior of the state’s institutions from the power excess. Within this context, we appreciate that the principle of proportionality represents such a criterion. The proportionality is a legal principle of the law, but at the same time it is a principle of the constitutional law and of other law branches. It expresses clearly the idea of balance, reasonability but also of adjusting the measures ordered by the state’s authorities to the situation in fact, respectively to the purpose for which they have been conceived. In our study we choose theoretical and jurisprudence arguments according to which the principle of proportionality can procedurally be determined and used to delimit the discretionary power and power abuse.
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