Recovery and status of shortnose sturgeon in the Hudson River

Shortnose sturgeon (Acipenser brevirostrum), an endangered species, has experienced a several-fold increase in abundance in the Hudson River in recent decades. This population growth followed a substantial improvement in water quality during the 1970s to a large portion (c. 40%) of the species' summertime nursery area. Age structure and growth were investigated to evaluate the hypothesis that improvements in water quality stimulated population recovery through increased survival of young of the year juveniles. Specimens were captured using gill nets bi-monthly from November 2003 to November 2004 (n = 596). Annuli in fin spine sections were used to generate estimates of sturgeon age. Based upon a marginal increment analysis, annuli were determined to form at an annual rate. Age determinations yielded a catch composed of age 5-30 years for sizes 49-105cm Total Length (n = 554). Individual growth rate (von Bertalanffy coefficients: TL, = 1045mm, K = 0.07) for the population was similar to previous growth estimates within the Hudson River as well as proximal estuaries. Hindcast year-class strengths, based upon a recent stock assessment (Bain et al. 2000) and corrected for gill net mesh selectivity and cumulative mortality indicated high recruitments (28,000-43,000 yearlings)during 1986-1992, which were preceded and succeeded by c.5-year periods of lower recruitment (5,000-1 5,000 yearlings). Recruitment patterns were corroborated by trends in shortnose sturgeon bycatch from a Hudson utilities-sponsored monitoring program. Results indicated that Hudson River shortnose sturgeon abundance increased due to the formation of several strong year-classes occurring about five years subsequent to improved water quality in important nursery and forage habitats in the upper Hudson River estuary. (PDF contains 108 pages.

Novel roles for IL-15 in T cell survival

Interleukin-15 (IL-15) is generally considered to be a regulator of T cell homeostasis because it works with other common gamma-chain cytokines like IL-2 and IL-7 to control the maintenance of naive and memory T cell populations. However, recent reports highlight new roles for IL-15 during the primary immune responses that involve promoting the survival of antigen-specific CD8+ T cells. These findings illuminate a previously unanticipated role for IL-15 in the generation and resolution of the effector CD8+ T cell response to pathogens

A Call to Arms: Interferons Prepare Bone Marrow Cells to Battle Peripheral Infections

Viral infection leads to the rapid production of type I interferons within infected tissues. In this issue of Cell Host & Microbe, Hermesh et al. (2010) demonstrate that interferons produced following respiratory viral infection program leukocytes in the bone marrow to resist infection before trafficking to the lung

The Role of Water in the Stability of Cratonic Keels

Cratons are typically underlain by large, deep, and old lithospheric keels (to greater than 200 km depth, greater than 2.5 Ga old) projecting into the asthenosphere (e.g., Jordan, 1978; Richardson et al., 1984). This has mystified Earth scientists as the dynamic and relatively hot asthenosphere should have eroded away these keels over time (e.g., Sleep, 2003; O'Neill et al., 2008; Karato, 2010). Three key factors have been invoked to explain cratonic root survival: 1) Low density makes the cratonic mantle buoyant (e.g., Poudjom Djomani et al., 2001). 2) Low temperatures (e.g., Pollack, 1986; Boyd, 1987), and 3) low water contents (e.g., Pollack, 1986), would make cratonic roots mechanically strong. Here we address the mechanism of the longevity of continental mantle lithosphere by focusing on the water parameter. Although nominally anhydrous , olivine, pyroxene and garnet can accommodate trace amounts of water in the form of H bonded to structural O in mineral defects (e.g., Bell and Rossman, 1992). Olivine softens by orders of magnitude if water (1-1000 ppm H2O) is added to its structure (e.g., Mackwell et al., 1985). Our recent work has placed constraints on the distribution of water measured in peridotite minerals in the cratonic root beneath the Kaapvaal in southern Africa (Peslier et al., 2010). At P greater than 5 GPa, the water contents of pyroxene remain relatively constant while those of olivine systematically decrease from 50 to less than 10 ppm H2O at 6.4 GPa. We hypothesized that at P greater than 6.4 GPa, i.e. at the bottom of the cratonic lithosphere, olivines are essentially dry (greater than 10 ppm H2O). As olivine likely controls the rheology of the mantle, we calculated that the dry olivines could be responsible for a contrast in viscosity between cratonic lithosphere and surrounding asthenosphere large enough to explain the resistance of cratonic root to asthenospheric delamination

γ-Herpesvirus Latency Is Preferentially Maintained in Splenic Germinal Center and Memory B Cells

The γ-herpesviruses are oncogenic B cell lymphotrophic viruses that establish life-long latency in the host. Murine γ-herpesvirus 68 (MHV-68) infection of mice represents a unique system for analyzing γ-herpesvirus latency in splenic B cells at different stages of infection. After intranasal infection with MHV-68 we analyzed the establishment of latency 14 days after infection, and the maintenance of latency 3 months after infection in different purified subpopulations of B cells in the spleen. The data show that MHV-68 latency is mainly established in germinal center B cells and that long-term latency is preferentially maintained in two different subsets of isotype-switched B cells, germinal center and memory B cells. Cell cycle analysis indicates that MHV-68 is located in both cycling and resting isotype-switched B cells. Analysis of viral gene expression showed that both lytic and latent viral transcripts were differentially expressed in germinal center and memory B cells during long-term latency. Together, these observations suggested that γ-herpesviruses exploit the B cell life cycle in the spleen

Type I Interferons Regulate Cytolytic Activity of Memory CD8+ T Cells in the Lung Airways during Respiratory Virus Challenge

SummaryMemory CD8+ T cells in the lung airways provide protection from secondary respiratory virus challenge by limiting early viral replication. Here, we demonstrate that although airway-resident memory CD8+ T cells were poorly cytolytic, memory CD8+ T cells recruited to the airways early during a recall response showed markedly enhanced cytolytic ability. This enhanced lytic activity did not require cognate antigen stimulation, but rather was dependent on STAT1 transcription factor signaling through the interferon-α receptor (Ifnar1), resulting in the antigen-independent expression of granzyme B protein in both murine and human virus-specific T cells. Signaling through Ifnar1 was required for the enhanced lytic activity and control of early viral replication by memory CD8+ T cells in the lung airways. These findings demonstrate that innate inflammatory signals act directly on memory T cells, enabling them to rapidly destroy infected host cells once they enter infected tissues

Water Content of Earth's Continental Mantle Is Controlled by the Circulation of Fluids or Melts

A key mission of the ARES Directorate at JSC is to constrain models of the formation and geological history of terrestrial planets. Water is a crucial parameter to be measured with the aim to determine its amount and distribution in the interior of Earth, Mars, and the Moon. Most of that "water" is not liquid water per se, but rather hydrogen dissolved as a trace element in the minerals of the rocks at depth. Even so, the middle layer of differentiated planets, the mantle, occupies such a large volume and mass of each planet that when it is added at the planetary scale, oceans worth of water could be stored in its interior. The mantle is where magmas originate. Moreover, on Earth, the mantle is where the boundary between tectonic plates and the underlying asthenosphere is located. Even if mantle rocks in Earth typically contain less than 200 ppm H2O, such small quantities have tremendous influence on how easily they melt (i.e., the more water there is, the more magma is produced) and deform (the more water there is, the less viscous they are). These two properties alone emphasize that to understand the distribution of volcanism and the mechanism of plate tectonics, the water content of the mantle must be determined - Earth being a template to which all other terrestrial planets can be compared

Tuning the confinement potential between spinons in the Ising chain CoNb2O6 using longitudinal fields and quantitative determination of the microscopic Hamiltonian

The Ising chain realizes the fundamental paradigm of spin fractionalization, where locally flipping a spin creates two domain walls (spinons) that can separate apart at no energy cost. In a quasi-one-dimensional system, the mean-field effects of the weak three-dimensional couplings confine the spinons into a Zeeman ladder of two-spinon bound states. Here, we experimentally tune the confinement potential between spinons in the quasi-one-dimensional Ising ferromagnet CoNb2O6 by means of an applied magnetic field with a large component along the Ising direction. Using high-resolution single crystal inelastic neutron scattering, we directly observe how the spectrum evolves from the limit of very weak confinement at low field (with many closely-spaced bound states with energies scaling as the field strength to the power 2/3) to very strong confinement at high field (where it consists of a magnon and a dispersive two-magnon bound state, with a linear field dependence). At intermediate fields, we explore how the higher-order bound states disappear from the spectrum as they move to higher energies and overlap with the two-particle continuum. By performing a global fit to the observed spectrum in zero field and high field applied along two orthogonal directions, combined with a quantitative parameterization of the interchain couplings, we propose a refined single chain and interchain Hamiltonian that quantitatively reproduces all observed dispersions and their field dependence.Comment: 20 pages, 13 figure