Rhesus macaques were studied to directly address the potential for plasmid-deficient Chlamydia trachomatis to serve as a live attenuated vaccine in the genital tract. Five repeated cervical ...inoculations of rhesus macaques with wild-type serovar D strain D/UW-3/Cx or a plasmid-deficient derivative of this strain, CTD153, resulted in infections with similar kinetics and induced comparable levels of protective immunity. After all animals received five challenges with D/UW-3/Cx, levels of inflammation observed grossly and histologically were similar between the groups. Animals in both groups developed evidence of oviduct dilatation; however, reduced oviduct dilatation was observed for "controllers," i.e., animals without detectable chlamydial DNA in the fimbriae at weeks 5 and 12. Grouping animals into "ascenders" and "controllers" revealed that elevated early T cell responses were associated with protection, whereas higher antibody responses were associated with ascension. Protected animals shared common major histocompatibility complex (MHC) alleles. Overall, genetic differences of individual animals, rather than the presence or absence of the chlamydial plasmid in the primary infecting strain, appeared to play a role in determining the outcome of infection.
Subglacial models represent moulins as cylinders or cones, but field observations suggest that the upper part of moulins in the Greenland Ice Sheet has more complex shapes. These more complex shapes ...should cause englacial water storage within moulins to vary as a function of depth, a relationship not currently accounted for in models. Here, we use a coupled englacial-subglacial channel model to explore how moulin shape affects depth-dependent moulin water storage and water pressure dynamics within a subglacial channel. We simulate seven different moulin shapes across a range of moulin sizes. We find that the englacial storage capacity at the water level is the main control over the daily water level oscillation range and that depth-varying changes in englacial water storage control the temporal shape of this oscillation. Further, the cross-sectional area of the moulin within the daily oscillation range, but not above or below this range, controls pressures within the connected subglacial channel. Specifically, large cross-sectional areas can dampen daily to weekly oscillations that occur in the surface meltwater supply. Our findings suggest that further knowledge of the shape of moulins around the equilibrium water level would improve englacial storage parameterization in subglacial hydrological models and aid predictions of hydrodynamic coupling.
Each summer, large volumes of surface meltwater drain off the Greenland ice sheet (GrIS) surface through moulins to the bed, impacting subglacial hydrology and ice flow dynamics. Supraglacial surface ...routing delays may propagate to englacial and subglacial hydrologic systems, requiring accurate assessment to correctly estimate subglacial effective pressures. We compare hourly supraglacial moulin discharge simulations from three surface meltwater routing models – the synthetic unit hydrograph (SUH), the bare-ice component of surface routing and lake filling (SRLF), and the rescaled width function (RWF) – for four internally drained catchments on the southwestern Greenland ice sheet surface. The routing models are forced identically using surface runoff from the Modèle Atmosphérique Régionale regional climate model (RCM). For each catchment, simulated moulin hydrographs are input to the SHAKTI subglacial hydrologic model to simulate diurnally varying subglacial effective-pressure variations in the vicinity of a single moulin. Overall, all three routing models produce more realistic moulin discharges than simply using RCM runoff outputs without surface routing but produce significant differences in peak moulin discharge and time to peak. In particular, the RWF yields later, smaller peak moulin discharges than the SUH or SRLF due to its representation of slow interfluve flow between supraglacial meltwater channels, and it can readily accommodate the seasonal evolution of supraglacial stream and river networks. Differences among the three routing models are reflected in a series of simple idealized subglacial hydrology simulations that yield different diurnal effective-pressure amplitudes; however, the supraglacial hydrologic system acts as short-term storage for surface meltwater, and the temporal mean effective pressure is relatively consistent across routing models.
Loss of the conserved "cryptic" plasmid from C. trachomatis and C. muridarum is pleiotropic, resulting in reduced innate inflammatory activation via TLR2, glycogen accumulation and infectivity. The ...more genetically distant C. caviae GPIC is a natural pathogen of guinea pigs and induces upper genital tract pathology when inoculated intravaginally, modeling human disease. To examine the contribution of pCpGP1 to C. caviae pathogenesis, a cured derivative of GPIC, strain CC13, was derived and evaluated in vitro and in vivo. Transcriptional profiling of CC13 revealed only partial conservation of previously identified plasmid-responsive chromosomal loci (PRCL) in C. caviae. However, 2-deoxyglucose (2DG) treatment of GPIC and CC13 resulted in reduced transcription of all identified PRCL, including glgA, indicating the presence of a plasmid-independent glucose response in this species. In contrast to plasmid-cured C. muridarum and C. trachomatis, plasmid-cured C. caviae strain CC13 signaled via TLR2 in vitro and elicited cytokine production in vivo similar to wild-type C. caviae. Furthermore, inflammatory pathology induced by infection of guinea pigs with CC13 was similar to that induced by GPIC, although we observed more rapid resolution of CC13 infection in estrogen-treated guinea pigs. These data indicate that either the plasmid is not involved in expression or regulation of virulence in C. caviae or that redundant effectors prevent these phenotypic changes from being observed in C. caviae plasmid-cured strains.
A series of NASA airborne lidars have been used in support of satellite laser altimetry missions. These airbornelaser altimeters have been deployed for satellite instrument development, for ...spaceborne data validation, and to bridge the data gap between satellite missions. We used data from ground-based Global Positioning System (GPS) surveys of an 11 km long track near Summit Station, Greenland, to assess the surface elevation bias and measurement precision of three airborne laser altimeters including the Airborne Topographic Mapper (ATM), the Land, Vegetation, and Ice Sensor (LVIS), and the Multiple Altimeter Beam Experimental Lidar (MABEL). Ground-based GPS data from the monthly ground-based traverses, which commenced in 2006, allowed for the assessment of nine airborne lidar surveys associated with ATM and LVIS between 2007 and 2016. Surface elevation biases for these altimeters over the flat, ice-sheet interior are less than 0.12 m, while assessments of measurement precision are 0.09 m or better. Ground-based GPS positions determined both with and without differential post-processing techniques provided internally consistent solutions. Results from the analyses of ground-based and airborne data provide validation strategy guidance for the Ice, Cloud, and land Elevation Satellite 2 (ICESat-2) elevation and elevation-change data products.
Objective
Chlamydia trachomatis infections are a significant cause of reproductive tract pathology. Protective and pathological immune mediators must be differentiated to design a safe and effective ...vaccine.
Methods
Wild‐type mice and mice deficient in IL‐22 and IL‐23 were infected intravaginally with Chlamydia muridarum, and their course of infection and oviduct pathology were compared. Local genital tract and draining lymph node immune responses were also examined in IL‐23‐deficient mice.
Results
IL‐22‐ and IL‐23‐deficient mice exhibited normal susceptibility to infection and oviduct pathology. IL‐23 was required for the development of a Chlamydia‐specific Th17 response in the lymph nodes and for production of IL‐22 and IL‐17 in the genital tract. However, influx of Th1 and innate immune cells was not compromised in the absence of IL‐23.
Conclusion
IL‐22 and IL‐23 play either redundant or minimal roles in the pathogenesis of Chlamydia infection in the mouse model. Induction of Th17‐associated cytokines by a Chlamydia vaccine should be avoided as these responses are not central to resolution of infection and have pathologic potential.
Nature Communications 7: Article number: 13903 (2016); Published 19 December 2016; Updated 7 February 2017 The original version of this Article contained a typographical error in the spelling of the ...author Stephen F. Price, which was incorrectly given as Stephen A. Price. This has now been correctedin both the PDF and HTML versions of the Article.
The impact of summer surface melt on Greenland Ice Sheet dynamics is modulated by the state of the subglacial hydrologic system. Studies of ice motion indicate that efficiency of the subglacial ...system increases over the melt season, decreasing the sensitivity of ice motion to surface melt inputs. However, the behavior of the subglacial hydrologic system is complex and some characteristics are still poorly constrained. Here we investigate the coevolution of subglacial hydrology and ice motion in the Pâkitsoq region of western Greenland during the 2011 melt season. We analyze measurements from 11 Global Positioning System stations, from which we derive ice velocity, longitudinal strain rates, and basal uplift, alongside observations of surface ablation and supraglacial lake drainages. We observe ice acceleration after the onset of local surface melting, followed by gradual ice deceleration, consistent with increasing subglacial efficiency. In the study area, supraglacial lake drainages cooccur with a change in regional strain rate patterns and ice deceleration, suggesting that lake drainages contribute to rapid subglacial reorganization. At lower ice surface elevations (below ~900 m above sea level), ice motion is correlated with both total basal uplift and its rate of change, while at higher elevations (~900–1,100 m above sea level), ice motion correlated only with the basal uplift rate. This pattern suggests that continued cavity growth or subglacial sediment dynamics may be important in the apparent increase in subglacial drainage efficiency at higher elevations in the ablation zone. Our results further suggest that transient subglacial behavior is important in the seasonal evolution of ice motion.
Plain Language Summary
Each summer, the margins of the Greenland Ice Sheet experience intense surface melting. This meltwater is routed over the surface in supraglacial streams and stored in supraglacial lakes, but eventually reaches the bed of the ice sheet via crevasses and moulins. The interaction between this meltwater and the overlying ice causes changes to the subglacial hydrologic system, which subsequently causes changes in ice motion. Here we use measurements from 11 Global Positioning System stations, alongside observations of surface melt rates and supraglacial lake drainages, to improve our understanding of the subglacial hydrologic system. In our study area, supraglacial lake drainages tend to cooccur with slowdowns in ice motion, suggesting that the rapid drainage of these large volumes of water can alter the subglacial hydrologic system, allowing it to more readily transmit meltwater. Our observations also indicate that at high elevations, the seasonal pattern of ice motion is controlled by small changes over large regions, either in sediments or in pockets of water on the downstream side of bedrock bumps, not necessarily by the formation of large subglacial channels. These findings suggest that current models of the subglacial system need modifications to include the physics associated with supraglacial lake drainages and small‐scale processes.
Key Points
Ice velocity in Pâkitsoq, western Greenland, exhibits clear signs of increased subglacial drainage efficiency over a melt season
Supraglacial lake drainage events can be associated with inferred transitions between inefficient and efficient subglacial drainage
Consistent with previous results, basal uplift rates are better correlated with horizontal ice velocity than total basal uplift
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