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Intriguing Question (intriguing + question)
Selected AbstractsMolecular markers of phase transition in locustsINSECT SCIENCE, Issue 1 2006ARNOLD DE LOOF Abstract The changes accompanying the transition from the gregarious to the solitary phase state in locusts are so drastic that for a long time these phases were considered as distinct species. It was Boris Uvarov who introduced the concept of polyphenism. Decades of research revealed that phase transition implies changes in morphometry, the color of the cuticle, behavior and several aspects of physiology. In particular, in the recent decade, quite a number of molecular studies have been undertaken to uncover phase-related differences. They resulted in novel insights into the role of corazonin, neuroparsins, some protease inhibitors, phenylacetonitrile and so on. The advent of EST-databases of locusts (e.g. Kang et al., 2004) is a most encouraging novel development in physiological and behavioral locust research. Yet, the answer to the most intriguing question, namely whether or not there is a primordial molecular inducer of phase transition, is probably not within reach in the very near future. [source] Structural mechanisms of multidrug recognition and regulation by bacterial multidrug transcription factorsMOLECULAR MICROBIOLOGY, Issue 4 2002Maria A. Schumacher Summary The increase in bacterial resistance to multiple drugs represents a serious and growing health risk. One component of multidrug resistance (MDR) is a group of multidrug transporters that are often regulated at the transcriptional level by repressors and/or activators. Some of these transcription factors are also multidrug-binding proteins, frequently recognizing the same array of drugs that are effluxed by the transporters that they regulate. How a single protein can recognize such chemically disparate compounds is an intriguing question from a structural standpoint and an important question in future drug development endeavours. Unlike the multidrug transporters, the cytosolic multidrug-binding regulatory proteins are more tractable systems for structural analyses. Here, we describe recent crystallographic studies on MarR, BmrR and QacR, three bacterial transcription regulators that are also multidrug-binding proteins. Although our understanding of multidrug binding and transcriptional regulation by MarR is in its initial stages, the structure of a BmrR,TPP+,DNA complex has revealed important insights into the novel transcription activation mechanism of the MerR family, and the structures of a QacR,DNA complex and QacR bound to six different drugs have revealed not only the mechanism of induction of this repressor but has afforded the first view of any MDR protein bound to multiple drugs. [source] Decidualization and implantation: Embryo-uterine bioinformatics at workMOLECULAR REPRODUCTION & DEVELOPMENT, Issue 2 2001Abraham L. Kierszenbaum The implantation of the blastocyst into a nurturing endometrium involves two overlapping steps: 1. The blastocyst-endometrial luminal epithelial attachment. 2. The decidualization of the endometrial stroma. An intriguing question is how does the blastocyst identify the uterine implantation site. Current research is focused on hypothetical soluble signaling molecules released by the blastocyst for conditioning a discrete uterine luminal epithelial domain for implantation. A still unresolved issue is the functional significance of receptor autophosphorylation following binding of uterine epithelial cell-derived heparin-binding epidermal growth factor-like growth factor to the epidermal growth factor receptor on trophoectodermic cell surfaces. With recent results hinting at the role of signaling proteins associated with the bone morphogenetic protein, fibroblast growth factor, WNT and hedgehog families to enable embryo implantation, the dynamics of uterine-embryo interaction becomes linked to fundamental cellular pathways of growth, differentiation and apoptosis. Mol. Reprod. Dev. 59:123,125, 2001. © 2001 Wiley-Liss, Inc. [source] Attachment and the processing of social information in adolescenceNEW DIRECTIONS FOR CHILD & ADOLESCENT DEVELOPMENT, Issue 117 2007Matthew J. Dykas Do internal working models of attachment influence the ways in which adolescents process social information? The chapter addresses this intriguing question by reviewing studies that have examined links between attachment and adolescents' memory, feedback seeking, perceptions of others, and secure base scripts. [source] Long-term landscape evolution: linking tectonics and surface processesEARTH SURFACE PROCESSES AND LANDFORMS, Issue 3 2007Paul Bishop Abstract Research in landscape evolution over millions to tens of millions of years slowed considerably in the mid-20th century, when Davisian and other approaches to geomorphology were replaced by functional, morphometric and ultimately process-based approaches. Hack's scheme of dynamic equilibrium in landscape evolution was perhaps the major theoretical contribution to long-term landscape evolution between the 1950s and about 1990, but it essentially ,looked back' to Davis for its springboard to a viewpoint contrary to that of Davis, as did less widely known schemes, such as Crickmay's hypothesis of unequal activity. Since about 1990, the field of long-term landscape evolution has blossomed again, stimulated by the plate tectonics revolution and its re-forging of the link between tectonics and topography, and by the development of numerical models that explore the links between tectonic processes and surface processes. This numerical modelling of landscape evolution has been built around formulation of bedrock river processes and slope processes, and has mostly focused on high-elevation passive continental margins and convergent zones; these models now routinely include flexural and denudational isostasy. Major breakthroughs in analytical and geochronological techniques have been of profound relevance to all of the above. Low-temperature thermochronology, and in particular apatite fission track analysis and (U,Th)/He analysis in apatite, have enabled rates of rock uplift and denudational exhumation from relatively shallow crustal depths (up to about 4 km) to be determined directly from, in effect, rock hand specimens. In a few situations, (U,Th)/He analysis has been used to determine the antiquity of major, long-wavelength topography. Cosmogenic isotope analysis has enabled the determination of the ,ages' of bedrock and sedimentary surfaces, and/or the rates of denudation of these surfaces. These latter advances represent in some ways a ,holy grail' in geomorphology in that they enable determination of ,dates and rates' of geomorphological processes directly from rock surfaces. The increasing availability of analytical techniques such as cosmogenic isotope analysis should mean that much larger data sets become possible and lead to more sophisticated analyses, such as probability density functions (PDFs) of cosmogenic ages and even of cosmogenic isotope concentrations (CICs). PDFs of isotope concentrations must be a function of catchment area geomorphology (including tectonics) and it is at least theoretically possible to infer aspects of source area geomorphology and geomorphological processes from PDFs of CICs in sediments (,detrital CICs'). Thus it may be possible to use PDFs of detrital CICs in basin sediments as a tool to infer aspects of the sediments' source area geomorphology and tectonics, complementing the standard sedimentological textural and compositional approaches to such issues. One of the most stimulating of recent conceptual advances has followed the considerations of the relationships between tectonics, climate and surface processes and especially the recognition of the importance of denudational isostasy in driving rock uplift (i.e. in driving tectonics and crustal processes). Attention has been focused very directly on surface processes and on the ways in which they may ,drive' rock uplift and thus even influence sub-surface crustal conditions, such as pressure and temperature. Consequently, the broader geoscience communities are looking to geomorphologists to provide more detailed information on rates and processes of bedrock channel incision, as well as on catchment responses to such bedrock channel processes. More sophisticated numerical models of processes in bedrock channels and on their flanking hillslopes are required. In current numerical models of long-term evolution of hillslopes and interfluves, for example, the simple dependency on slope of both the fluvial and hillslope components of these models means that a Davisian-type of landscape evolution characterized by slope lowering is inevitably ,confirmed' by the models. In numerical modelling, the next advances will require better parameterized algorithms for hillslope processes, and more sophisticated formulations of bedrock channel incision processes, incorporating, for example, the effects of sediment shielding of the bed. Such increasing sophistication must be matched by careful assessment and testing of model outputs using pre-established criteria and tests. Confirmation by these more sophisticated Davisian-type numerical models of slope lowering under conditions of tectonic stability (no active rock uplift), and of constant slope angle and steady-state landscape under conditions of ongoing rock uplift, will indicate that the Davis and Hack models are not mutually exclusive. A Hack-type model (or a variant of it, incorporating slope adjustment to rock strength rather than to regolith strength) will apply to active settings where there is sufficient stream power and/or sediment flux for channels to incise at the rate of rock uplift. Post-orogenic settings of decreased (or zero) active rock uplift would be characterized by a Davisian scheme of declining slope angles and non-steady-state (or transient) landscapes. Such post-orogenic landscapes deserve much more attention than they have received of late, not least because the intriguing questions they pose about the preservation of ancient landscapes were hinted at in passing in the 1960s and have recently re-surfaced. As we begin to ask again some of the grand questions that lay at the heart of geomorphology in its earliest days, large-scale geomorphology is on the threshold of another ,golden' era to match that of the first half of the 20th century, when cyclical approaches underpinned virtually all geomorphological work. Copyright © 2007 John Wiley & Sons, Ltd. [source] Twenty Years of the Journal of Product Innovation Management: History, Participants, and Knowledge Stock and FlowsTHE JOURNAL OF PRODUCT INNOVATION MANAGEMENT, Issue 3 2007Wim Biemans The Journal of Product Innovation Management (JPIM) serves as a marketplace for science-based, innovative ideas that are produced and consumed by scholars and businesspeople. Now that JPIM has existed for 20 years, two intriguing questions emerge: (1) How has the journal evolved over time in terms of knowledge stock, that is, what are the characteristics of the growing stock of knowledge published by JPIM over the years; and (2) how has the journal evolved in knowledge flow, that is, how is JPIM influenced by other scientific publications and what is its impact on other journals? In terms of knowledge stock, over 35% of the articles published over the 20 years investigate processes and metrics for performance management. The next most frequently published area was strategy, planning, and decision making (20%), followed by customer and market research (17%). The dominant research method used was a cross-sectional large-sample survey, and the focus most usually is at the project level of the firm. The large majority of JPIM authors (60%) have a marketing background, with the remaining 40% representing numerous functional domains. Academics at all levels publish in JPIM, and though most authors hail from North America, the Dutch are a significant second group. JPIM was analyzed from a knowledge-flow perspective by looking at the scientific sources used by JPIM authors to develop their ideas and articles. To this end a bibliometric analysis was performed by analyzing all references in articles published in JPIM. During 1984,2003 JPIM published 488 articles, containing 10,314 references to journals and 6,533 references to other sources. Some 20% of these references (2,020) were self-references to JPIM articles. The remaining 8,294 journal references were to articles in 287 journals in the fields of management (25%), marketing (24%), and management of technology (14%). However, it should be pointed out that many domains were dominated by a limited number of journals. The second component of knowledge flow concerns the extent to which the ideas developed in JPIM are consumed by other authors. Again, bibliometric analysis was used to analyze data from the Social Sciences Citation Index (SSCI) about citations to JPIM in other journals. For the period 1984,2005, the SSCI registered 7,773 citations to JPIM in 2,067 articles published in 278 journals (including the 2,020 self-citations in JPIM). The functional areas most frequently citing JPIM are management of technology (25%), marketing (15%), management (14%), and operations management and management science (9%). Again, several domains were found to be dominated by a limited number of journals. At the level of individual journals the analysis shows a growing impact of JPIM on management of technology journals. The knowledge-flow analysis demonstrates how JPIM functions as a bridge between the knowledge from various domains and the body of knowledge on management of technology. It suggests a growing specialization of the field of technology innovation management, with JPIM being firmly entrenched as the acknowledged leading journal. [source] Crystallization and preliminary X-ray crystallographic studies of the Z-DNA-binding domain of a PKR-like kinase (PKZ) in complex with Z-DNAACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 3 2009Doyoun Kim PKZ, a PKR-like eIF2, kinase, consists of a Z-DNA-specific binding domain (Z,) and an eIF2, kinase domain. The kinase activity of PKZ is modulated by the binding of Z, to Z-DNA. The mechanisms underlying Z-DNA binding and the subsequent stimulation of PKZ raise intriguing questions. Interestingly, the Z-DNA-binding domain of PKZ from goldfish (Carassius auratus; caZ,PKZ) shows limited sequence homology to other canonical Z, domains, suggesting that it may have a distinct Z-DNA-recognition mode. In this study, the Z-DNA-binding activity and stoichiometry of caZ,PKZ were confirmed using circular dichroism (CD). In addition, preliminary X-ray studies of the caZ,PKZ,Z-DNA complex are reported as the first step in the determination of its three-dimensional structure. Bacterially expressed recombinant caZ,PKZ was purified and crystallized with Z-DNA at 295,K using the microbatch method. X-ray diffraction data were collected to 1.7,Å resolution with an Rmerge of 7.4%. The crystals belonged to the monoclinic space group C2, with unit-cell parameters a = 55.54, b = 49.93, c = 29.44,Å, , = 96.5°. Structural analysis of caZ,PKZ,Z-DNA will reveal the binding mode of caZ,PKZ to Z-DNA and its relevance to other Z-DNA-binding proteins. [source] | ||||||||||