Partners in Crime: Genes within an Amplicon Collude to Globally Deregulate Chromatin in Lymphoma

In this issue of Cancer Cell, Rui et al. identify JAK2 and JMJDC2 as two contiguous, coamplified oncogenes in primary mediastinal B cell and Hodgkin lymphoma. Together, JAK2 and JMJD2C induce major changes in chromatin structure and gene expression. Targeting these proteins with small molecules represents a new avenue for therapy

Sprouty1 regulates reversible quiescence of a self-renewing adult muscle stem cell pool during regeneration.

Satellite cells are skeletal muscle stem cells capable of self-renewal and differentiation after transplantation, but whether they contribute to endogenous muscle fiber repair has been unclear. The transcription factor Pax7 marks satellite cells and is critical for establishing the adult satellite cell pool. By using a lineage tracing approach, we show that after injury, quiescent adult Pax7(+) cells enter the cell cycle; a subpopulation returns to quiescence to replenish the satellite cell compartment, while others contribute to muscle fiber formation. We demonstrate that Sprouty1 (Spry1), a receptor tyrosine kinase signaling inhibitor, is expressed in quiescent Pax7(+) satellite cells in uninjured muscle, downregulated in proliferating myogenic cells after injury, and reinduced as Pax7(+) cells re-enter quiescence. We show that Spry1 is required for the return to quiescence and homeostasis of the satellite cell pool during repair. Our results therefore define a role for Spry1 in adult muscle stem cell biology and tissue repair

Local states of free bose fields

These notes contain an extended version of lectures given at the ``Summer School on Large Coulomb Systems'' in Nordfjordeid, Norway, in august 2003. They furnish a short introduction to the theory of quantum harmonic systems, or free bose fields. The main issue addressed is the one of local states. I will adopt the definition of Knight of ``strictly local excitation of the vacuum'' and will then state and prove a generalization of Knight's Theorem which asserts that finite particle states cannot be perfectly localized. It will furthermore be explained how Knight's a priori counterintuitive result can be readily understood if one remembers the analogy between finite and infinite dimensional harmonic systems alluded to above. I will also discuss the link between the above result and the so-called Newton-Wigner position operator thereby illuminating, I believe, the difficulties associated with the latter. I will in particular argue that those difficulties do not find their origin in special relativity or in any form of causality violation, as is usually claimed

Search for plant biomagnetism with a sensitive atomic magnetometer

We report what we believe is the first experimental limit placed on plant biomagnetism. Measurements with a sensitive atomic magnetometer were performed on the Titan arum (Amorphophallus titanum) inflorescence, known for its fast bio-chemical processes while blooming. We find that the surface magnetic field from these processes, projected along the Earth's magnetic field, and measured at the surface of the plant, is less then ~0.6uG.Comment: 5 pages, 5 figures, to be published - modified one sentence in abstract + reformatted fi

Communication between receptors for different ligands on a single cell...

Receptors for the third component of complement (C3) on cultured human monocytes (MO) bind ligand-coated particles but do not initiate phagocytosis. The function of these receptors, however, is altered dramatically after MO attach to surfaces coated with fibronectin (FN) or after MO are exposed to phorbol esters. FN and phorbol esters "activate" C3 receptors such that they promote vigorous phagocytosis. Here we show that activation of C3 receptors requires the continuous presence of FN or phorbol esters and is rapidly reversible when these stimuli are removed. Activation does not change the number or distribution of C3 receptors on the surface of MO. We conclude that the function of C3 receptors is regulated by reversible reactions that are initiated by ligation of a different class of receptors on the surface of the same cell

Big sugar in southern Africa : rural development and the perverted potential of sugar/ethanol exports

This paper asks how investment in large-scale sugar cane production has contributed, and will contribute, to rural development in southern Africa. Taking a case study of the South African company Illovo in Zambia, the argument is made that the potential for greater tax revenue, domestic competition, access to resources and wealth distribution from sugar/ethanol production have all been perverted and with relatively little payoff in wage labour opportunities in return. If the benefits of agro-exports cannot be so easily assumed, then the prospective 'balance sheet' of biofuels needs to be re-examined. In this light, the paper advocates smaller-scale agrarian initiatives

Imperfect Imitation Can Enhance Cooperation

The promotion of cooperation on spatial lattices is an important issue in evolutionary game theory. This effect clearly depends on the update rule: it diminishes with stochastic imitative rules whereas it increases with unconditional imitation. To study the transition between both regimes, we propose a new evolutionary rule, which stochastically combines unconditional imitation with another imitative rule. We find that, surprinsingly, in many social dilemmas this rule yields higher cooperative levels than any of the two original ones. This nontrivial effect occurs because the basic rules induce a separation of timescales in the microscopic processes at cluster interfaces. The result is robust in the space of 2x2 symmetric games, on regular lattices and on scale-free networks.Comment: 4 pages, 4 figure

Seasonal cycles in testicular activity, gonadotropin, and thyroxine in the painted turtle, Chrysemys picta, under natural conditions

Plasma levels of testosterone (T), thyroxine (T4) and follicle-stimulating hormone (FSH) were measured in a field population of the painted turtle, Chrysemys picta, in Michigan. All three hormones showed pronounced seasonality; plasma luteinizing hormone (LH) remained nondetectable. Plasma T and FSH concentrationswere highly correlated and exhibited biphasic cycles with peaks in spring and fall, whereas T4 showed a single peak in summer, coincident with the nadir in T. Hormone levels were minimal on the day that animals emerged from hibernation at the end of March; T and FSH then increased rapidly (in ca. 1 week after emergence) to a transient peak that persisted for onlyca. 2 weeks. Plasma T and FSH rose again in September before the onset of hibernation and shortly after the late summer peak in spermatogenetic recrudescence. Plasma T4 increased more gradually after emergence in spring and did not peak for 1-2 months, coincident with the nadir in T. The profile in plasma FSH is consistent with the view that this gonadotropin may regulate androgen secretion but it did not show the expected relationship to the spermatogenetic cycle. Separate studies indicated that the turtles are sensitive to capture and handling; hormone levels (especially androgen) fall precipitously within a day of capture. These "stress" effects may account for discrepancies with previous studies of plasma T in this species.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/25629/1/0000179.pd