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Subtle Shifts (subtle + shift)
Selected AbstractsDistribution and functional characterization of human Nav1.3 splice variantsEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 1 2005R. Thimmapaya Abstract The focus of the present study is the molecular and functional characterization of four splice variants of the human Nav1.3 , subunit. These subtypes arise due to the use of alternative splice donor sites of exon 12, which encodes a region of the , subunit that resides in the intracellular loop between domains I and II. This region contains several important phosphorylation sites that modulate Na+ channel kinetics in related sodium channels, i.e. Nav1.2. While three of the four Nav1.3 isoforms, 12v1, 12v3 and 12v4 have been previously identified in human, 12v2 has only been reported in rat. Herein, we evaluate the distribution of these splice variants in human tissues and the functional characterization of each of these subtypes. We demonstrate by reverse transcriptase-polymerase chain reaction (RT-PCR) that each subtype is expressed in the spinal cord, thalamus, amygdala, cerebellum, adult and fetal whole brain and heart. To investigate the functional properties of these different splice variants, each , subunit isoform was cloned by RT-PCR from human fetal brain and expressed in Xenopus oocytes. Each isoform exhibited functional voltage-dependent Na+ channels with similar sensitivities to tetrodotoxin (TTX) and comparable current amplitudes. Subtle shifts in the V1/2 of activation and inactivation (2,3 mV) were observed among the four isoforms, although the functional significance of these differences remains unclear. This study has demonstrated that all four human splice variants of the Nav1.3 channel , subunit are widely expressed and generate functional TTX-sensitive Na+ channels that likely modulate cellular excitability. [source] Differences in litter mass change mite assemblage structure on a deciduous forest floorECOGRAPHY, Issue 6 2006Graham H. R. Osler Few mechanisms that determine the assemblage structure of mites have been identified. Whilst the relative abundance of soil fauna is known to change with humus form, the degree to which the quantity of litter inputs play a part in these changes has not been investigated. We tested the response of oribatid and mesostigmatid mites in litter and soil layers to increasing levels of birch Betula pubescens litter to test whether litter mass could affect the mite assemblage. Six litter treatments (1, 2, 4, 8 and 12×natural litter mass and complete litter removal) were established in November 2004 and the soil and litter communities sampled in October 2005. Species composition of oribatids was distinct for the soil and litter. There was no apparent effect of increasing litter mass on the soil mite assemblage. In the litter layer, the number of oribatids g,1 of litter showed a strong negative relationship with increasing litter mass whilst the number of mesostigmatids g,1 of litter was unresponsive to litter mass. Hence, the relative abundance of these two groups altered with increasing litter mass. The response of the oribatid groups Oppiidae and Poronota followed this negative relationship with litter mass but Phthiracaridae appeared less affected. Consequently, there was a subtle shift in the relative abundance of these groups with increasing litter mass. Our results demonstrate that oribatids as a whole and within groups respond in a predictable manner to increases in litter mass whilst mesostigmatids are unresponsive. Whilst there are undoubtedly biological and physical aspects that vary with litter mass, litter mass itself, is able to explain some patterns in the assemblage of oribatid mites. [source] From Treatise to Textbook: A History of Writing About Household ManagementFAMILY & CONSUMER SCIENCES RESEARCH JOURNAL, Issue 2 2008Sharon Y. Nickols The origins of contemporary writing about household management in the United States have been traced back to Catharine Beecher's A Treatise on Domestic Economy. The expansion of academic programs in home economics, the rise of research using the scientific method, and the changing economic and social conditions during the early 20th century contributed to the transition from treatises offering household advice based on Christian precepts and customary roles to more analytical approaches to household management and the publication of textbooks for college courses. Using qualitative research methods, this study traced the 75-year history of home management/family resource management textbooks published in the United States. The themes found throughout this period show both subtle shifts and dramatic changes in seven areas of analysis: the rationale for studying home management, the theoretical conceptualization of management, what is managed, individual and family concepts within home management, internal/external emphasis on resource management, pedagogical style, and audience. [source] Lessons from the past: the collapse of Jamaican coral reefsFISH AND FISHERIES, Issue 2 2009Marah J. Hardt Abstract Since Pre-Columbian times, humans have exploited Jamaican marine ecosystems with significant consequences for flora and fauna. This study focuses on the history of reef fish exploitation in Jamaica, from first human occupation to the present day, to determine how past fishing activities contributed to subsequent declines in the coral reef ecosystem. The pattern of declining reef fish populations was nonlinear. Reef fish first declined in prehistoric times but then potentially recovered, following genocide of the native human population. Reduced fishing pressure lasted until the mid-19th century. At that time, depletion of reef fish populations again occurred with a precipitous decline from the 1850s to the 1940s. The final shift from relatively abundant to overfished marine fauna corresponded to subtle changes in fish trap design as well as development of recreational fishing. Government subsidies throughout the second half of the 20th century exacerbated the declines. This analysis shows that local artisanal fisheries with relatively low levels of effort and seemingly subtle shifts in technology can significantly impact the coral reef ecosystem and that declines occurred decades to centuries before modern ecological studies began. This research shows how historical analysis can be a powerful tool to minimize shifted baselines and establish realistic targets for recovery and sustainable management of marine ecosystems. [source] All three Ca2+ -binding loops of photoproteins bind calcium ions: The crystal structures of calcium-loaded apo-aequorin and apo-obelinPROTEIN SCIENCE, Issue 3 2005Lu Deng HLH, helix,loop,helix; HSQC, heteronuclear single quantum coherence; RMSD, root mean square deviation; SAD, single wavelength anomalous dispersion Abstract The crystal structures of calcium-loaded apoaequorin and apo-obelin have been determined at resolutions 1.7 Å and 2.2 Å, respectively. A calcium ion is observed in each of the three EF-hand loops that have the canonical calcium-binding sequence, and each is coordinated in the characteristic pentagonal bipyramidal configuration. The calcium-loaded apo-proteins retain the same compact scaffold and overall fold as the unreacted photoproteins containing the bound substrate, 2-hydroperoxycoelenterazine, and also the same as the Ca2+ -discharged obelin bound with the product, coelenteramide. Nevertheless, there are easily discerned shifts in both helix and loop regions, and the shifts are not the same between the two proteins. It is suggested that these subtle shifts are the basis of the ability of these photoproteins to sense Ca2+ concentration transients and to produce their bioluminescence response on the millisecond timescale. A mechanism of intrastructural transmission of the calcium signal is proposed. [source] THE ENCYCLOPÉDIE AND THE IDEA OF THE DECORATIVE ARTSART HISTORY, Issue 2 2005Élisabeth Lavezzi The decorative arts do not appear as a category of useful knowledge in Diderot's and d'Alembert's Encyclopédie but those arts now called decorative arts, such as cabinet-making, were central to the eighteenth-century Parisian economy and a defining feature of a publication which set itself the task of raising the status of the useful arts. This essay explores the antecedents of the notion of the decorative arts in the history of ideas. By comparing Renaissance, baroque and enlightened art theory, it charts the faltering emergence of a definition of arts such as marquetry that no longer sees them as either materially or procedurally dependent on the finer arts of painting or architecture. In the subtle shifts of meaning the object gives way to the maker as principal element upon which the definition of an art turns. [source] New insights into the binding mode of coenzymes: structure of Thermus thermophilus,1 -pyrroline-5-carboxylate dehydrogenase complexed with NADP+ACTA CRYSTALLOGRAPHICA SECTION F (ELECTRONIC), Issue 6 2007Eiji Inagaki ,1 -Pyrroline-5-carboxylate dehydrogenase (P5CDh) is known to preferentially use NAD+ as a coenzyme. The kcat value of Thermus thermophilus P5CDh (TtP5CDh) is four times lower for NADP+ than for NAD+. The crystal structure of NADP+ -bound TtP5CDh was solved in order to study the structure,activity relationships for the coenzymes. The binding mode of NADP+ is essentially identical to that in the previously solved NAD+ -bound form, except for the regions around the additional 2,-phosphate group of NADP+. The coenzyme-binding site can only accommodate this group by the rotation of a glutamate residue and subtle shifts in the main chain. The 2,-phosphate of NADP+ increases the number of hydrogen bonds between TtP5CDh and NADP+ compared with that between TtP5CDh and NAD+. Furthermore, the phosphate of the bound NADP+ would restrict the `bending' of the coenzyme because of steric hindrance. Such bending is important for dissociation of the coenzymes. These results provide a plausible explanation of the lower turnover rate of NADP+ compared with NAD+. [source] | ||||||||||||||||