Chronic helminth infection burden differentially affects haematopoietic cell development while ageing selectively impairs adaptive responses to infection

Throughout the lifespan of an individual, the immune system undergoes complex changes while facing novel and chronic infections. Helminths, which infect over one billion people and impose heavy livestock productivity losses, typically cause chronic infections by avoiding and suppressing host immunity. Yet, how age affects immune responses to lifelong parasitic infection is poorly understood. To disentangle the processes involved, we employed supervised statistical learning techniques to identify which factors among haematopoietic stem and progenitor cells (HSPC), and both innate and adaptive responses regulate parasite burdens and how they are affected by host age. Older mice harboured greater numbers of the parasites’ offspring than younger mice. Protective immune responses that did not vary with age were dominated by HSPC, while ageing specifically eroded adaptive immunity, with reduced numbers of naïve T cells, poor T cell responsiveness to parasites, and impaired antibody production. We identified immune factors consistent with previously-reported immune responses to helminths, and also revealed novel interactions between helminths and HSPC maturation. Our approach thus allowed disentangling the concurrent effects of ageing and infection across the full maturation cycle of the immune response and highlights the potential of such approaches to improve understanding of the immune system within the whole organism

Meteorology of Jupiter's Equatorial Hot Spots and Plumes from Cassini

We present an updated analysis of Jupiter's equatorial meteorology from Cassini observations. For two months preceding the spacecraft's closest approach, the Imaging Science Subsystem (ISS) onboard regularly imaged the atmosphere. We created time-lapse movies from this period in order to analyze the dynamics of equatorial hot spots and their interactions with adjacent latitudes. Hot spots are quasi-stable, rectangular dark areas on visible-wavelength images, with defined eastern edges that sharply contrast with surrounding clouds, but diffuse western edges serving as nebulous boundaries with adjacent equatorial plumes. Hot spots exhibit significant variations in size and shape over timescales of days and weeks. Some of these changes correspond with passing vortex systems from adjacent latitudes interacting with hot spots. Strong anticyclonic gyres present to the south and southeast of the dark areas appear to circulate into hot spots. Impressive, bright white plumes occupy spaces in between hot spots. Compact cirrus-like 'scooter' clouds flow rapidly through the plumes before disappearing within the dark areas. These clouds travel at 150-200 m/s, much faster than the 100 m/s hot spot and plume drift speed. This raises the possibility that the scooter clouds may be more illustrative of the actual jet stream speed at these latitudes. Most previously published zonal wind profiles represent the drift speed of the hot spots at their latitude from pattern matching of the entire longitudinal image strip. If a downward branch of an equatorially-trapped Rossby waves controls the overall appearance of hot spots, however, the westward phase velocity of the wave leads to underestimates of the true jet stream speed.Comment: 33 pages, 11 figures; accepted for publication in Icarus; for supplementary movies, please contact autho

Crossing the Boundaries in Planetary Atmospheres - From Earth to Exoplanets

The past decade has been an especially exciting time to study atmospheres, with a renaissance in fundamental studies of Earths general circulation and hydrological cycle, stimulated by questions about past climates and the urgency of projecting the future impacts of humankinds activities. Long-term spacecraft and Earth-based observation of solar system planets have now reinvigorated the study of comparative planetary climatology. The explosion in discoveries of planets outside our solar system has made atmospheric science integral to understanding the diversity of our solar system and the potential habitability of planets outside it. Thus, the AGU Chapman Conference Crossing the Boundaries in Planetary Atmospheres From Earth to Exoplanets, held in Annapolis, MD from June 24-27, 2013 gathered Earth, solar system, and exoplanet scientists to share experiences, insights, and challenges from their individual disciplines, and discuss areas in which thinking broadly might enhance our fundamental understanding of how atmospheres work

Longitudinal Variations in Jupiter's Winds

Long-term studies of Jupiter's zonal wind field revealed temporal variations on the order of 20 to 40 m/s at many latitudes, greater than the typical data uncertainties of 1 to 10 m/s. No definitive periodicities were evident, however, though some latitudinally-confined signals did appear at periods relevant to the Quasi- Quadrennial Oscillation (Simon-Miller & Gierasch, Icarus, in press). As the QQO appears, from vertical temperature profiles, to propagate downward, it is unclear why a signal is not more obvious, unless other processes dominate over possibly weaker forcing from the QQO. An additional complication is that zonal wind profiles represent an average over some particular set of longitudes for an image pair and most data sets do not offer global wind coverage. Lien avoiding known features, such as the large anticyclonic vortices especially prevalent in the south, there can be distinct variations in longitude. We present results on the full wind field from Voyager and Cassini data, showing apparent longitudinal variations of up to 60 m/s or more. These are particularly obvious near disruptions such as the South Equatorial Disturbance, even when the feature itself is not clearly visible. These two dates represent very different states of the planet for comparison: Voyagers 1 & 2 flew by Jupiter shortly after a global upheaval, while many regions were in a disturbed state, while the Cassini view is typical of a more quiescent period present during much of the 1990s and early 2000s

Supplemented nutrition decreases helminth burden and increases drug efficacy in a natural host–helminth system

Gastrointestinal helminths are common parasites of humans, wildlife, and livestock, causing chronic infections. In humans and wildlife, poor nutrition or limited resources can compromise individuals’ immune response, predisposing them to higher helminth burdens. This relationship has been tested in laboratory models by investigating infection outcomes following reductions of specific nutrients. However, much less is known about how diet supplementation can impact susceptibility to infection, acquisition of immunity, and drug efficacy in natural host-helminth systems. We experimentally supplemented the diet of wood mice Apodemus sylvaticus) with high quality nutrition and measured resistance to the common gastrointestinal nematode Heligmosomoides polygyrus. To test whether diet can enhance immunity to reinfection, we also administered anthelmintic treatment at random in both natural and captive populations. Supplemented wood mice were more resistant to H. polygyrus infection, cleared worms more efficiently after treatment, avoided a post-treatment infection rebound, produced stronger general and parasite-specific antibody responses, and maintained better body condition. In addition, when applied in conjunction with anthelmintic treatment, supplemented nutrition significantly reduced H. polygyrus transmission potential. These results show the rapid and extensive benefits of a well-balanced diet and have important implications for both disease control and wildlife health under changing environmental conditions

Inertioelastic Poiseuille flow over a wavy surface

Streamwise boundary undulations induce spanwise vorticity in flows. In Newtonian flow, vorticity decays exponentially with distance from the undulation. However, recent theory for inertioelastic polymeric flow predicts vorticity amplification in a "critical layer" far from the site of disturbance. Here we present the first experimental evidence for the existence of such critical layers, demonstrating their measurable role in real polymeric flows with inertia. These vorticity amplification effects should be considered in all evaluations of vorticity dynamics in inertioelastic flows with streamline curvature

Poiseuille flow over a wavy surface

We present a detailed series of experiments using spatially resolved flow velocimetry to examine the flow of Newtonian fluids through rectangular channels with one wavy surface of wave number k. The glass channels are fabricated by the method of selective laser-induced etching, which allows them to be made with a high (quasi-2D) aspect ratio (width/depth, w/2d=5) and with an accurate wave profile of small relative amplitude (A/d=0.05,A<k). Following the prior theoretical work for plane Couette flow over a wavy surface [Charru and Hinch, J. Fluid Mech. 414, 195 (2000)], we examine the influence of two dimensionless parameters (the normalized channel half-depth α=kd and the viscous length scale θ) on the penetration depth P of the perturbations that the wavy surface induces to the Poiseuille base flow. The asymptotic analysis by Charru and Hinch predicted three regimes of behavior classified as “shallow viscous” (P≈α), “deep viscous” (P≈1), and “inviscid” (P∼θ). All three regimes are here verified experimentally. Minor differences in details of the “phase diagram” for the flow regimes in α−θ parameter space observed between Poiseuille and plane Couette flow are attributed to the contrasting boundary conditions in the different flow configurations. Our experimental results also compare favorably to results from linear theory for a Poiseuille base flow and thus establish a detailed experimental complement to the theory

“Phase diagram” for viscoelastic Poiseuille flow over a wavy surface

We experimentally examine the Poiseuille flow of viscoelastic fluids over wavy surfaces. Five precision microfabricated flow channels are utilized, each of depth 2d = 400 mu m, spanwise width omega = 10d and with a sinusoidal undulation of amplitude A = d/20 on one of the spanwise walls. The undulation wavelength lambda is varied between each of the channels, providing dimensionless channel depths alpha in the range 0.2 pi <= alpha= 2 pi d/lambda <= 3.2 pi. Nine viscoelastic polymer solutions are formulated, spanning more than four orders in elasticity number El and are tested in the wavy channels over a wide range of Reynolds and Weissenberg numbers. Flow velocimetry is used to observe and measure the resulting flow patterns. Perturbations to the Poiseuille base flow caused by the wavy surfaces are quantified by the depth of their penetration P into the flow domain. Consistent with theoretical predictions made for wavy plane-Couette flow [J. Page and T. A. Zaki, "Viscoelastic shear flow over a wavy surface," J. Fluid Mech. 801, 392-429 (2016)], we observe three distinct flow regimes ("shallow elastic," "deep elastic" and "transcritical") that can be assembled into a "phase diagram" spanned by two dimensionless parameters: alpha and the depth of the theoretically predicted critical layer Sigma similar to root El. Our results provide the first experimental verification of this phase diagram and thus constitute strong evidence for the existence of the predicted critical layer. In the inertio-elastic transcritical regime, a surprising amplification of the perturbation occurs at the critical layer, strongly influencing P. These effects are of likely importance in widespread inertio-elastic flows in pipes and channels, such as in polymer turbulent drag reduction