Sort Of Order Research Articles

Engineering of ribozyme-based riboswitches for mammalian cells

Artificial RNA riboswitches – apart from protein-based gene regulation systems, which have been known about for a long time – have become increasingly important in biotechnology and synthetic biology. Aptamer-controlled hammerhead ribozymes (so-called aptazymes) have been shown to be a versatile platform for the engineering of novel gene regulators. Since aptazymes are cis-acting elements that are located in the untranslated regions of a gene of interest, their application does not need any further protein co-factor. This presents the opportunity to simplify complex gene networks while simultaneously expanding the repertoire of available parts. Nevertheless, the generation of novel aptazymes requires a functional aptamer–ribozyme connection, which can be difficult to engineer. This article describes a novel approach for using fluorescence activated cell sorting (FACS) in order to identify functional aptazymes in bacteria and their subsequent transfer into mammalian cells.

"As Full of Grief as Age": "King Lear" as Tragic Ancestor to "No Country for Old Men"

O Sir, you are old.Nature in you stands on very vergeOf his confine (Regan, King Lear II.iv.139-141)I always thought when I got older that God would sort of come into my life in some way. He didnt. I dont blame him. (Uncle Ellis, No Country for Old Men 267)In final of his thirteen soliloquies that punctuate each episode of action in Cormac McCarthy's bleak novel No Country for Old Men, SheriffEd Tom Bell finds himself silently observing stone water trough. The contrast between this quiet moment and what to this point has been Bell's turbulent investigation of horribly botched drug transaction is striking, both to reader and to Bell himself. Remembering that trough in question is constantly kept full by galvanized metal pipe, Bell begins to make inferences maker behind such solidly constructed yet seemingly trivial piece of work:[T]his man had set down with hammer and chisel and carved out stone water trough to last ten thousand years. Why was that? What was it that he had faith in? It wasnt that nothin would change. Which is what you might think, I suppose. He had to know bettern that. (306)Change, Bell has come to realize, is only constant. His world is one in which cattle rustlers with whom sheriffs were formerly charged with putting to justice now seem almost quaint-having evolved into morally bankrupt drug runners and mercenaries. It is world in which men identified in novel's title are doomed to extinction if they fail to adapt to changing times. It is also world in which, as Bell further realizes, stone trough is worth careful consideration, if only because its concrete shape and clear, simple function make it one of an increasingly few dependable, tangible entities in his experience.The depth of Bell's despondency at end of novel-It was defeat, (306) third-person narrative succinctly tells us page earlier-can only be as profound as it is because Bell is an man. His world view, which has always hinged on faith in some sort of divine justice and order in universe, now seems hopelessly obsolete and he knows it. Because of his age, because of nature of his crisis of conscience so late in life, and because his general outlook has just been inextricably altered from glimpse directly into face of evil, Bell recalls one of literature's most familiar old men: King Lear. As distant as McCarthy and Shakespeare seem, both chronologically and stylistically, novelist's work has certain quality that has drawn critics to compare it to some of behemoths of Western Literary canon. Critics have routinely cited litany of American novelists as direct influences on McCarthy. In review of McCarthy's 1998 novel Cities of Plain, New York Times reviewer Michiko Kakatuni refers to author as a direct descendent of Hemingway (E1). Scott Esposito has called him the heir of that ultimate Southern stylist, William Faulkner (Esposito). In tracing his work's lineage, others have gone farther back: Critic Peter Josyph goes as far as to outline connection between McCarthy's 1985 novel Meridian and epic poem Beowulf in his essay Blood Music, relationship that Rick Wallach expands on in his essay From Beowulf to Meridian.Inevitably, some readers have made intriguing, if improbable, comparison between McCarthy and Shakespeare. In notes from her 2007 production of King Lear at New Jersey Shakespeare Theater, director Bonnie J. Monte uses an excerpt from McCarthy's 2006 novel The Road, dark portrait of father and son's journey through bleak, post-apocalyptic world. The play, she says, is about world completely out of balance, awash in chaos, and leaderless (Monte). The same can be said of No Country for Old Men, whose ending recalls those of Shakespeare's bloodiest tragedies. The similarities between two pieces-in terms of hero's central dilemma and its tragic implications, as opposed to surface details of plot-are more than skin deep. …

Emerging Powers in an Age of Disorder

Randall Schweller THE DRAMATIC RISE OF CHINA AND INDIA AMONG OTHERS HAS SET THE STAGE for a fundamental rethinking of world politics in an age of the waning dominance of US power as a force for remaking the world in its own image. While Pax Americana is not yet teetering on the edge of collapse, the consensus opinion is that the relative decline of the United States is probably irreversible and its unipolar moment will soon give way to something new. A to multi-polarity is one way of describing this shift. It tells us that several great powers will emerge to challenge US primacy. That is all. The more important question is: What sort of global order will emerge on the other side of the transition from unipolarity to multipolarity? Will it be one of peace and plenty or and scarcity? On this issue, experts are divided into two camps, pessimists and optimists. Pessimists believe that the coming multipolar world--like the one that held sway over international politics from 1648 to 1945--will be permeated by problems of insecurity, rivalry, arms races, nationalism, and fierce competition for scarce resources. (1) Embedding their arguments in examinations of historical power shifts, such as those provoked by the rise of Napoleonic France or the unification of Germany in 1871, they predict that the United States and China will soon engage in an intense security competition with considerable potential for war. This conflict forecast is grounded in the assumption that history unfolds in repeating cycles of global war that destroy the old international order and replace it with a new one. Consistent with the time's metaphor of history, time has no direction; apparent motions are merely stages of ever-present and never-changing cycles. The future, therefore, will resemble the past. In contrast, optimists see a smooth evolutionary transition from unipolarity to multipolarity, as the great powers, old and new, find ways to build and jointly manage a new global architecture that preserves the essential features of the existing liberal order. (2) For them, multipolarity implies multilateralism. Embracing principles and practices of restraint, accommodation, reciprocity, and cooperation, the great powers will work in concert to establish mutually acknowledged roles and responsibilities to comanage an evolving but stable international order that benefits all of them. The return of multipolarity will usher in a new age of liberal peace, prosperity, and progress built on the rule of law. Swords will be beaten into ploughshares, and a harmony of interests will reign among the states and peoples of the world. It is a vision of concert, grounded in the assumption that history moves forward in a progressive direction--one consistent with the time's arrow metaphor of historical direction. (3) I argue that the prediction of great-power is overly pessimistic, whereas the expectation of a great-power concert is too hopeful. Fears that China's rise will incite war with the United States are unwarranted. The destructiveness of nuclear weapons and the benefits of economic globalization have made war among the great powers unthinkable. The cycle of hegemonic war and change has been replaced by a perpetual peace, just as liberals claim. Ironically, this is precisely why optimists are too sanguine about the future. International order--particularly one that is legitimate, efficient, and dynamic--requires periodic global wars, roughly every 100 years or so. Otherwise, inertia and decay set in. Hegel pointed this out in 1821: War is not to be regarded as an absolute evil. Just as the blowing of the winds preserves the sea from foulness which would be the result of a long calm, so also corruption in nations would be the result of prolonged, let alone 'perpetual,' peace.4 Whether domestic or international, political systems undisturbed by war cannot cleanse and renew themselves; like still seas, they become foul. …

A Quick Algorithm for Attribute Reduction Based on Divide and Conquer Method

Knowledge reduction is one of the most important contributions of rough set theory. High efficient algorithm is necessary for attribute reduction. In this paper, combining given attribute order and quick sort method, a heuristic algorithm for attribute reduction is developed. In this method, the objects in universe are divided into many small parts on the attributes by divide and conquer method, and different granules in different granular levels are obtained. The small ones can be processed quickly, so a fast heuristic algorithm for attribute reduction is proposed. Simulation experiment results illustrate the high efficiency of the improved knowledge reduction algorithm.

Trailblazers in Adolescent and Young Adult Oncology.

The development of adolescent and young adult (AYA) oncology as a burgeoning discipline that is now into its own adolescence may be best illustrated by the surge in AYA oncology publications in peer-reviewed journals during the past three years. Prior to 2007, the number of articles identified by the search term ‘‘adolescents young adults cancer’’ in the PubMed database ranged from 129 to 381 per year. Since then, the number increased to 598 in 2007, 1971 in 2008, and 4045 in 2009. The dramatic increase is still well short of the 7000–7500 articles per year that the ‘‘children cancer’’ search term identifies, especially when one considers that the number of cancer patients in the AYA age group is four to six times greater, depending on what age range is used for the AYA group. Nonetheless, the change in publication rate of AYA cancer reports and reviews is striking testimony of need and partial success. To understand the history that led to this revolution, several of its pioneers in England, the United States, and Canada were convened for a roundtable discussion to offer their recall. As described below, the original seed appears to have been sowed in England, thanks to Ian Lewis and London’s Teenage Cancer Trust. A root took hold a decade later when national statistics in the United States showed a survival progress gap that was analogized to the famous London Tube gap between the platform and the Underground train. The stems that then broke ground were conferences, organizations, hospital and outpatient programs, scientific reviews, and international collaborations. The participants in this Roundtable undoubtedly neglected many other events along the way, but they are all appreciative of the emerging buds and blossoms of AYA oncology. Most of all, they sense that AYAs around the world will ultimately truly benefit in improved prevention, early detection, and treatment of cancer during the prime of their lives.

Kryzys społecznej gospodarki rynkowej w kontekście procesów globalizacji

In the context of globalization processes, the social market economy (SME) is in the crisis. Reflection on the features of that model is closely related with the scientific dispute over its designation. It could be perceived as a theory, political program, sort of economic order, structure, model or system of economic and social development. Sometimes it is seemed as an idealistic vision or even political utopia (Niklas Luhmann). Others (eg. Peter Koslowski) argue that this system has come to an end. In favor of this thesis they refer to various arguments: lack of consensus on redistribution, demographic crisis, depletion of solidarity resources, intergenerational imbalance that threatens the retirement systems and many others. Despite the range of these arguments, it appears that the SME still has a specific potential that could be freed. Combating difficulties associated with globalization processes such as: dominance of the economy over politics, ‘tax starvation’ of the welfare state, marginalization of trade unions, dispersion of ownership and its detachment from responsibility, ‘financialization’ of economy, dominance of ‘casino capitalism’, could help to heal SME. The crisis on financial markets might be paradoxically an opportunity to return to the ethical foundations of the SME.

Technology-Aware Algorithm Design for Neural Spike Detection, Feature Extraction, and Dimensionality Reduction

Applications such as brain-machine interfaces require hardware spike sorting in order to 1) obtain single-unit activity and 2) perform data reduction for wireless data transmission. Such systems must be low-power, low-area, high-accuracy, automatic, and able to operate in real time. Several detection, feature-extraction, and dimensionality-reduction algorithms for spike sorting are described and evaluated in terms of accuracy versus complexity. The nonlinear energy operator is chosen as the optimal spike-detection algorithm, being most robust over noise and relatively simple. Discrete derivatives is chosen as the optimal feature-extraction method, maintaining high accuracy across signal-to-noise ratios with a complexity orders of magnitude less than that of traditional methods such as principal-component analysis. We introduce the maximum-difference algorithm, which is shown to be the best dimensionality-reduction method for hardware spike sorting.

The Liberal International Order and its Discontents

The American-led world system is troubled. Some would argue that it is in crisis. But what sort of crisis is it? Is it a crisis of America’s position in the global system or is it a deeper world historical transition in which liberalism and liberal international order are at risk? Is the American-led ‘liberal era’ ending, or is it transforming into a new sort of liberal order? In this article, I argue that the American liberal hegemonic order is in crisis. But it is a crisis of authority within liberal international order and not a crisis of its underlying principles and organisational logic. That is, it is a crisis of the American governance of liberal order and not of liberal order itself. The crisis of liberalism today will ultimately bring forth ‘more liberalism’. The post-Cold War liberal international order is more durable than many think. Russia and China are not inevitable enemies of Western international order. A grand alternative to liberal order does not exist. To put it sharply: the pathway to the future still runs through institutions and relationships created over the last 60 years. American unipolarity will eventually give way to something new. Power and authority will shift in the global system as they have over the centuries. But rival orders will not emerge — even if new leaders will. In the decades ahead, the United States and Europe and rising states — many of which are in Asia — will have more reasons and not fewer reasons to cooperate in open and rule-based ways. The future still belongs to the liberal international order.

Pseudo Amino Acid Composition and its Applications in Bioinformatics, Proteomics and System Biology

With the avalanche of protein sequences generated in the post-genomic age, it is highly desired to develop automated methods for efficiently identifying various attributes of uncharacterized proteins. This is one of the most important tasks facing us today in bioinformatics, and the information thus obtained will have important impacts on the development of proteomics and system biology. To realize that, one of the keys is to find an effective model to represent the sample of a protein. The most straightforward model in this regard is its entire amino acid sequence; however, the entire sequence model would fail to work when the query protein did not have significant homology to proteins of known characteristics. Thus, various non-sequential models or discrete models were proposed. The simplest discrete model is the amino acid (AA) composition. Using it to represent a protein, however, all the sequence-order information would be completely lost. To cope with such a dilemma, the concept of pseudo amino acid (PseAA) composition was introduced. Its essence is to keep using a discrete model to represent a protein yet without completely losing its sequence-order information. Therefore, in a broad sense, the PseAA composition of a protein is actually a set of discrete numbers that is derived from its amino acid sequence and that is different from the classical AA composition and able to harbour some sort of sequence order or pattern information. Ever since the first PseAA composition was formulated to predict protein subcellular localization and membrane protein types, it has stimulated many different modes of PseAA composition for studying various kinds of problems in proteins and proteins-related systems. In this review, we shall give a brief and systematic introduction of various modes of PseAA composition and their applications. Meanwhile, the challenges for finding the optimal PseAA composition are also briefly discussed.

Avoiding trivia: the role of strategic planning in American foreign policy

After World War II, George Kennan became the State Department's first director of policy planning. Secretary of State George Marshall's initial advice to Kennan: above all, avoid trivia. Concentrate on the forest, not the trees, and don't lost sight of the big picture. Easier said than done. Avoiding Trivia critically assesses the past, future, and future role and impact of long-term strategic planning in foreign policy. Strategic planning needs to be a more integral part of America's foreign policymaking. Thousands of troops are engaged in combat while homeland security concerns remain. In such an environment, long-term coordination of goals and resources would seem to be of paramount importance. But history tells us that such cohesiveness and coherence are tremendously difficult to establish, much less maintain. Can policy planners --in the Pentagon, the State Department, Treasury, NSC, and National Intelligence Council --rise to the challenge? Indeed, is strategic planning a viable concept in 21st century foreign policy? These crucial questions guide this eye-opening book. The contributors include key figures from the past few decades of foreign policy and planning --individuals responsible for imposing some sort of order and strategic priority on foreign policy in a world that changes by the minute. They provide authoritative insight on the difficulties and importance of thinking and acting in a coherent way, for the long term. Contributors: Andrew P. N. Erdmann, Peter Feaver, Aaron L. Friedberg, David F. Gordon, Richard N. Haass, William Inboden, Bruce W. Jentleson, Steven D. Krasner, Jeffrey W. Legro, Daniel Twining, Thomas Wright, Amy B. Zegart.

Glucose uptake and its effect on gene expression in prochlorococcus.

The marine cyanobacteria Prochlorococcus have been considered photoautotrophic microorganisms, although the utilization of exogenous sugars has never been specifically addressed in them. We studied glucose uptake in different high irradiance- and low irradiance-adapted Prochlorococcus strains, as well as the effect of glucose addition on the expression of several glucose-related genes. Glucose uptake was measured by adding radiolabelled glucose to Prochlorococcus cultures, followed by flow cytometry coupled with cell sorting in order to separate Prochlorococcus cells from bacterial contaminants. Sorted cells were recovered by filtration and their radioactivity measured. The expression, after glucose addition, of several genes (involved in glucose metabolism, and in nitrogen assimilation and its regulation) was determined in the low irradiance-adapted Prochlorococcus SS120 strain by semi-quantitative real time RT-PCR, using the rnpB gene as internal control. Our results demonstrate for the first time that the Prochlorococcus strains studied in this work take up glucose at significant rates even at concentrations close to those found in the oceans, and also exclude the possibility of this uptake being carried out by eventual bacterial contaminants, since only Prochlorococcus cells were used for radioactivity measurements. Besides, we show that the expression of a number of genes involved in glucose utilization (namely zwf, gnd and dld, encoding glucose-6-phosphate dehydrogenase, 6-phosphogluconate dehydrogenase and lactate dehydrogenase, respectively) is strongly increased upon glucose addition to cultures of the SS120 strain. This fact, taken together with the magnitude of the glucose uptake, clearly indicates the physiological importance of the phenomenon. Given the significant contribution of Prochlorococcus to the global primary production, these findings have strong implications for the understanding of the phytoplankton role in the carbon cycle in nature. Besides, the ability of assimilating carbon molecules could provide additional hints to comprehend the ecological success of Prochlorococcus.

Order−Disorder Antiferroelectric Phase Transition in a Hybrid Inorganic−Organic Framework with the Perovskite Architecture

[(CH3)2NH2]Zn(HCOO)3, 1, adopts a structure that is analogous to that of a traditional perovskite, ABX3, with A = [(CH3)2NH2], B = Zn, and X = HCOO. The hydrogen atoms of the dimethyl ammonium cation, which hydrogen bond to oxygen atoms of the formate framework, are disordered at room temperature. X-ray powder diffraction, dielectric constant, and specific heat data show that 1 undergoes an order-disorder phase transition on cooling below 156 K. We present evidence that this is a classical paraelectric to antiferroelectric phase transition that is driven by ordering of the hydrogen atoms. This sort of electrical ordering associated with order-disorder phase transition is unprecedented in hybrid frameworks and opens up an exciting new direction in rational synthetic strategies to create extended hybrid networks for applications in ferroic-related fields.

Specific Heat of YbIr2

Specific heat of flux-grown single crystals of YbIr2 in zero and applied magnetic field indicates a more complicated magnetic behavior than was inferred from earlier magnetic susceptibility measurements. The possibility of defect-induced Kondo behavior mixed together with some sort of antiferromagnetic local order is discussed.

Effect of heterogeneous solute distribution on the anomalous thermomechanical response of Cu–Ni alloy single crystals below 50 K

The anomalous temperature dependence of the critical resolved shear stress (CRSS) of Cu–Ni alloys observed below a certain temperature, T o = 50 K, has been accounted for by introducing a stress-concentration factor f(T) = [(T ′ + T o)/(T ′ + T)] in the monotonic CRSS–T formulation of the kink-pair nucleation model of solid-solution hardening. The empirical constant T ′ is found to depend not only on the solute concentration, c, but also on the nature of the solute distribution in the host lattice. It is found that the solute distribution is random for c ≤ 14 at.% Ni in the Cu lattice and for c ≤ 20 at.% Cu in the Ni lattice, whereas some sort of local ordering occurs for all other values of solute concentration.

Determining blood cell size using microfluidic hydrodynamics

Microfluidic flow cytometers currently analyze far fewer parameters than conventional flow cytometry or fluorescence activated cell sorting (FACS) in order to minimize cost and complexity. There is a need for microfluidic devices that analyze more and or new cell parameters with compact and minimal means. Here we show a new and explicitly microfluidic parameter, “hydrodynamic” cell size, and compare it to forward scatter in conventional flow cytometry. The hydrodynamic size of cells is determined by the degree of lateral displacement experienced while traveling through a 1.2-mm-wide non-clogging array of micro-fabricated obstacles. We show comparable size resolution between the microfluidic device and forward scatter in conventional flow cytometry and without the need to lyse red blood cells. We use the device to differentiate healthy lymphocytes from malignant lymphocytes by size alone and we use the device to detect increased numbers of activated lymphocytes in blood as a result of exposure to staphylococcal enterotoxin B (SEB), a potential bioterror agent. Together the results demonstrate a microfluidic device that performs some of the measurement and separation tasks of a flow cytometer but at a potentially lower cost and complexity.

A new polynomial algorithm for a parallel identical scheduling problem

A precedence order is defined based on the release dates of jobs’ direct successors. Using the defined precedence order and Heap Sort, a new polynomial algorithm is provided which aims to solve the parallel scheduling problem P|p j = 1, r j , outtree| Σ C j . The new algorithm is shown to be more compact and easier to implement.

Cascaded interferometric imaging spectrometer

We present what we believe to be a novel method for order sorting a Fabry-Perot interferometer using a Fourier transform spectrometer (FTS) in tandem. We demonstrate how the order sorting is achieved using a model instrument response as an example of an instrument working in the 5-25 microm band, although the method is generally applicable at all wavelengths. We show that an instrument of this type can be realized with a large bandwidth, a large field of view, and good transmission efficiency. These attributes make this instrument concept a useful technique in applications where true imaging spectroscopy is required, such as mapping large astronomical sources. We compare the performance of the new instrument to grating and standard FTS instruments in circumstances where the measurement is background and detector noise limited. We use a figure of merit based on the field of view and speed of detection and find that the new system has a speed advantage over a FTS with the same field of view in all circumstances. The instrument will be faster than a grating instrument with the same spectral resolution once the field of view is >13 times larger under high background conditions and >50 times larger with detector performances that match the photon noise from Zodiacal light.

Reduction of Oxidative Stress in Bovine Spermatozoa During Flow Cytometric Sorting

The goal of the study was to investigate the effect of antioxidant supplementation on the quality of frozen-thawed flow cytometrically sorted bull spermatozoa. Twelve ejaculates from two Holstein Friesian bulls were sorted according to the Beltsville Sperm Sexing Technology. Each ejaculate was divided into three parts and processed as (i) unsorted controls, (ii) according to a standard sorting protocol and (iii) in the presence of different antioxidants (S-AO). Cooling and freezing of the samples were performed in the same way for all three groups, except that antioxidants were added to the TRIS-egg-yolk freezing extender for those semen samples that were already sorted in the presence of antioxidants. The semen quality in frozen-thawed samples was determined by morphology analysis immediately after thawing, motility estimation in a thermo-resistance test after 0, 6, 12 and 24 h incubation at 37 degrees C and Fluorescein isothiocyanate conjugated PNA/propidium iodide (FITC-PNA/PI) staining after 0, 12 and 24 h of incubation at 37 degrees C. There was a significantly higher (p < 0.05) percentage of motile spermatozoa in S-AO samples in comparison to unsorted frozen-thawed control at 0, 6 and 24 h after thawing and compared with normally sorted samples at all times after thawing. The percentage of damaged acrosomes was significantly lower (p < 0.05) in S-AO samples than in the unsorted controls (20.8 +/- 6.9% vs 30.3 +/- 12.0%). The percentage of morphologically abnormal spermatozoa in this group was significantly lower (p < 0.05) than in the unsorted controls and normally sorted samples (25.8 +/- 5.2%, 36.0 +/- 12.5% and 35.1 +/- 7.4%, respectively). Analysis of frozen-thawed spermatozoa with FITC/PI revealed no significant difference in membrane integrity at 0 and 12 h after sorting, but after 24 h of incubation the S-AO samples had a significantly higher (p < 0.001) percentage of spermatozoa with intact membranes in comparison to unsorted controls and normally sorted semen (40.7 +/- 6.3%, 7.8 +/- 4.7% and 7.4 +/- 4.6%, respectively). The percentage of acrosome-reacted spermatozoa was significantly lower (p < 0.05) in the S-AO samples than in the unsorted controls (14.1 +/- 7.5%, 23.4 +/- 5.4% and 28.8 +/- 6.3% vs 25.9 +/- 14.4%, 38.5 +/- 16.7% and 79.8 +/- 4.1%, for 0, 12 and 24 h after thawing, respectively) and in comparison to normally sorted semen 24 h after thawing (67.3 +/- 10.0%). This study demonstrates the highly protective effects of antioxidants on the quality of flow cytometrically sorted frozen-thawed bull spermatozoa.

Liquid Modernity, Complexity and Turbulence

The main ideas underlying Bauman’s liquid modernity are explained and then extended to incorporate current ideas about complexity and turbulence. This combination is used to argue that although Bauman himself refuses to offer any resolution to the paradoxes of liquid modernity, complexity theory may be useful: in particular the argument that the seemingly chaotic may actually result in some sort of order. The section also points to the ways in which liquid modernity provides a constant reminder of the underside of contemporary existence; vagabonds and waste as well as tourists and flexibility.

Developmental stage–specific shift in responsiveness to chemokines during human B-cell development

To better understand the role of chemokines during human B-cell development in bone marrow. Differentiation stage-specific B cells (pro-B, pre-B, immature, and mature) were analyzed for chemokine receptor expression and for migration to corresponding ligands. We also hypothesized that inflammatory conditions may cause the upregulation of certain chemokine receptors on early B cells, rendering them sensitive to extramedullary chemotactic cues. To test this hypothesis, we used human pre-B 697 cells to investigate whether various inflammatory agents could modify chemokine receptor expression and function. Chemotaxis to CXCL12 was observed for all B cell subsets. However, chemotactic responses to CCL19, CCL21, CXCL13, and CCL20 were limited to late-stage, IgM+ bone marrow B cells (immature B and mature B). Chemotactic responses to corresponding ligands correlated with the pattern of chemokine receptor expression. The expression of CCR7, however, was low on early (pro-B and pre-B) B cells and did not induce chemotaxis. Interestingly, both CCL19 and CCL21 could trigger ERK1/2 phosphorylation in early B cells. Exposure of pre-B 697 cells to TNF-alpha upregulated CCR7 and CXCR5 expression, whereas it had no effect on CCR6 surface expression. Correspondingly, TNF-alpha-stimulated pre-B cells chemotaxed towards CCL19 and CXCL13, in contrast to non-TNF-alpha-stimulated controls. We postulate that CXCR5, CCR7, and CCR6 participate in bone marrow trafficking and/or bone marrow egress of late-stage B cells under steady-state conditions, whereas inflammation-induced expression of CCR7 and CXCR5 may facilitate early B-cell emigration out of the bone marrow and their positioning in secondary lymphoid organs.