Social integration confers thermal benefits in a gregarious primate

1. Sociality has been shown to have adaptive value for gregarious species, with more socially integrated animals within groups experiencing higher reproductive success and longevity. The value of social integration is often suggested to derive from an improved ability to deal with social stress within a group; other potential stressors have received less attention. 2. We investigated the relationship between environmental temperature, an important non-social stressor, and social integration in wild female vervet monkeys (Chlorocebus pygerythrus), using implanted data loggers to obtain direct measures of core body temperature. 3. Heterothermy (as measured by 24-h amplitude of body temperature) increased, and 24-h minima of body temperature decreased, as the 24-h minimum ambient temperature decreased. As winter progressed, monkeys became increasingly heterothermic and displayed lower 24-h minima of body temperature. 4. Monkeys with a greater number of social partners displayed a smaller 24-h amplitude (that is, were more homoeothermic) and higher 24-h minima of body temperature (that is, became less hypothermic), than did animals with fewer social partners. 5. Our findings demonstrate that social integration has a direct influence on thermoregulatory ability: individual animals that form and maintain more social relationships within their group experience improved thermal competence compared to those with fewer social relationships. 6. Given the likely energetic consequences of thermal benefits, our findings offer a viable physiological explanation that can help account for variations in fitness in relation to individual differences in social integration

Keeping cool in the heat: behavioral thermoregulation and body temperature patterns in wild vervet monkeys

Objectives: Climate change is having a significant impact on biodiversity and increasing attention is therefore being devoted to identifying the behavioral strategies that a species uses to cope with climatic stress. We explore how wild vervet monkeys (Chlorocebus pygerythrus) respond to heat stress, and how behavioral adaptations are used to regulate body temperature. Materials and methods: We implanted wild vervet monkeys with temperature-sensitive data loggers and related the body temperature rhythms of these animals to their use of thermoregulatory behaviors. Results: Environmental temperature had a positive effect on the mean, minima and maxima of daily body temperatures. Environmental temperature had a positive effect on the amount of time that vervet monkeys spent in the shade, and animals that spent more time in the shade had lower body temperature maxima. Drinking water did not have a proximate effect on body temperature, most likely a consequence of their regular access to drinking water. Body temperatures were observed to decrease after swimming events, but tended to return to pre-swim temperatures within 1 hr, suggesting a limited thermal benefit of this behavior. Conclusions: Our data support the view that vervet monkeys cope well in the heat, and use behavior as a means to aid thermoregulation. The ability of primates to be flexible in their use of thermoregulatory behaviors can contribute positively to their capacity to cope with environmental variability. However, given its broad effect on plant productivity and habitat loss, climate change is a major threat to species' biogeographical distribution and survival

Thermal consequences of increased pelt loft infer an additional utilitarian function for grooming: Thermal Benefits of Grooming

A strong case has been made that the primary function of grooming is hygienic. Nevertheless, its persistence in the absence of hygienic demand, and its obvious tactical importance to members of primate groups, underpins the view that grooming has become uncoupled from its utilitarian objectives and is now principally of social benefit. We identify improved thermoregulatory function as a previously unexplored benefit of grooming and so broaden our understanding of the utilitarian function of this behavior. Deriving the maximum thermal benefits from the pelt requires that it be kept clean and that the loft of the pelt is maintained (i.e., greater pelt depth), both of which can be achieved by grooming. In a series of wind-tunnel experiments, we measured the heat transfer characteristics of vervet monkey (Chlorocebus pygerythrus) pelts in the presence and absence of backcombing, which we used as a proxy for grooming. Our data indicate that backcombed pelts have improved thermal performance, offering significantly better insulation than flattened pelts and, hence, better protection from the cold. Backcombed pelts also had significantly lower radiant heat loads compared to flattened pelts, providing improved protection from radiant heat. Such thermal benefits, therefore, furnish grooming with an additional practical value to which its social use is anchored. Given the link between thermoregulatory ability and energy expenditure, our findings suggest that grooming for thermal benefits may be an important explanatory variable in the relationship between levels of sociability and individual fitness

Propagation of an Earth-directed coronal mass ejection in three dimensions

Solar coronal mass ejections (CMEs) are the most significant drivers of adverse space weather at Earth, but the physics governing their propagation through the heliosphere is not well understood. While stereoscopic imaging of CMEs with the Solar Terrestrial Relations Observatory (STEREO) has provided some insight into their three-dimensional (3D) propagation, the mechanisms governing their evolution remain unclear due to difficulties in reconstructing their true 3D structure. Here we use a new elliptical tie-pointing technique to reconstruct a full CME front in 3D, enabling us to quantify its deflected trajectory from high latitudes along the ecliptic, and measure its increasing angular width and propagation from 2-46 solar radii (approximately 0.2 AU). Beyond 7 solar radii, we show that its motion is determined by an aerodynamic drag in the solar wind and, using our reconstruction as input for a 3D magnetohydrodynamic simulation, we determine an accurate arrival time at the Lagrangian L1 point near Earth.Comment: 5 figures, 2 supplementary movie

String Theory on Warped AdS_3 and Virasoro Resonances

We investigate aspects of holographic duals to time-like warped AdS_3 space-times--which include G\"odel's universe--in string theory. Using worldsheet techniques similar to those that have been applied to AdS_3 backgrounds, we are able to identify space-time symmetry algebras that act on the dual boundary theory. In particular, we always find at least one Virasoro algebra with computable central charge. Interestingly, there exists a dense set of points in the moduli space of these models in which there is actually a second commuting Virasoro algebra, typically with different central charge than the first. We analyze the supersymmetry of the backgrounds, finding related enhancements, and comment on possible interpretations of these results. We also perform an asymptotic symmetry analysis at the level of supergravity, providing additional support for the worldsheet analysis.Comment: 24 pages + appendice

Representation of Time-Varying Stimuli by a Network Exhibiting Oscillations on a Faster Time Scale

Sensory processing is associated with gamma frequency oscillations (30–80 Hz) in sensory cortices. This raises the question whether gamma oscillations can be directly involved in the representation of time-varying stimuli, including stimuli whose time scale is longer than a gamma cycle. We are interested in the ability of the system to reliably distinguish different stimuli while being robust to stimulus variations such as uniform time-warp. We address this issue with a dynamical model of spiking neurons and study the response to an asymmetric sawtooth input current over a range of shape parameters. These parameters describe how fast the input current rises and falls in time. Our network consists of inhibitory and excitatory populations that are sufficient for generating oscillations in the gamma range. The oscillations period is about one-third of the stimulus duration. Embedded in this network is a subpopulation of excitatory cells that respond to the sawtooth stimulus and a subpopulation of cells that respond to an onset cue. The intrinsic gamma oscillations generate a temporally sparse code for the external stimuli. In this code, an excitatory cell may fire a single spike during a gamma cycle, depending on its tuning properties and on the temporal structure of the specific input; the identity of the stimulus is coded by the list of excitatory cells that fire during each cycle. We quantify the properties of this representation in a series of simulations and show that the sparseness of the code makes it robust to uniform warping of the time scale. We find that resetting of the oscillation phase at stimulus onset is important for a reliable representation of the stimulus and that there is a tradeoff between the resolution of the neural representation of the stimulus and robustness to time-warp. Author Summary Sensory processing of time-varying stimuli, such as speech, is associated with high-frequency oscillatory cortical activity, the functional significance of which is still unknown. One possibility is that the oscillations are part of a stimulus-encoding mechanism. Here, we investigate a computational model of such a mechanism, a spiking neuronal network whose intrinsic oscillations interact with external input (waveforms simulating short speech segments in a single acoustic frequency band) to encode stimuli that extend over a time interval longer than the oscillation's period. The network implements a temporally sparse encoding, whose robustness to time warping and neuronal noise we quantify. To our knowledge, this study is the first to demonstrate that a biophysically plausible model of oscillations occurring in the processing of auditory input may generate a representation of signals that span multiple oscillation cycles.National Science Foundation (DMS-0211505); Burroughs Wellcome Fund; U.S. Air Force Office of Scientific Researc

Tumor-Specific Hsp70 Plasma Membrane Localization Is Enabled by the Glycosphingolipid Gb3

Human tumors differ from normal tissues in their capacity to present Hsp70, the major stress-inducible member of the HSP70 family, on their plasma membrane. Membrane Hsp70 has been found to serve as a prognostic indicator of overall patient survival in leukemia, lower rectal and non small cell lung carcinomas. Why tumors, but not normal cells, present Hsp70 on their cell surface and the impact of membrane Hsp70 on cancer progression remains to be elucidated.Although Hsp70 has been reported to be associated with cholesterol rich microdomains (CRMs), the partner in the plasma membrane with which Hsp70 interacts has yet to be identified. Herein, global lipid profiling demonstrates that Hsp70 membrane-positive tumors differ from their membrane-negative counterparts by containing significantly higher amounts of globotriaoslyceramide (Gb3), but not of other lipids such as lactosylceramide (LacCer), dodecasaccharideceramide (DoCer), galactosylceramide (GalCer), ceramide (Cer), or the ganglioside GM1. Apart from germinal center B cells, normal tissues are Gb3 membrane-negative. Co-localization of Hsp70 and Gb3 was selectively determined in Gb3 membrane-positive tumor cells, and these cells were also shown to bind soluble Hsp70-FITC protein from outside in a concentration-dependent manner. Given that the latter interaction can be blocked by a Gb3-specific antibody, and that the depletion of globotriaosides from tumors reduces the amount of membrane-bound Hsp70, we propose that Gb3 is a binding partner for Hsp70. The in vitro finding that Hsp70 predominantly binds to artificial liposomes containing Gb3 (PC/SM/Chol/Gb3, 17/45/33/5) confirms that Gb3 is an interaction partner for Hsp70.These data indicate that the presence of Gb3 enables anchorage of Hsp70 in the plasma membrane of tumors and thus they might explain tumor-specific membrane localization of Hsp70

MicroRNA-Related Cofilin Abnormality in Alzheimer's Disease

Rod-like structures composed of actin and the actin-binding protein cofilin are found in Alzheimer's disease (AD) patients. However, the mechanisms underlying formation of these structures and their pathological consequences are still largely unknown. We found that microRNAs 103 and 107 repress translation of cofilin, and that reduced levels of miR-103 or miR-107 are associated with elevated cofilin protein levels and formation of rod-like structures in a transgenic mouse model of AD. These results suggest that microRNAs may play an important role in cytoskeletal pathology in AD

Molecular and clinical determinants of response and resistance to rucaparib for recurrent ovarian cancer treatment in ARIEL2 (Parts 1 and 2)

ARIEL2 (NCT01891344) is a single-arm, open-label phase 2 study of the PARP inhibitor (PARPi) rucaparib in relapsed high-grade ovarian carcinoma. In this post hoc exploratory biomarker analysis of pre- and post-platinum ARIEL2 samples, RAD51C and RAD51D mutations and high-level BRCA1 promoter methylation predict response to rucaparib, similar to BRCA1/BRCA2 mutations. BRCA1 methylation loss may be a major cross-resistance mechanism to platinum and PARPi. Genomic scars associated with homologous recombination deficiency are irreversible, persisting even as platinum resistance develops, and therefore are predictive of rucaparib response only in platinum-sensitive disease. The RAS, AKT, and cell cycle pathways may be additional modulators of PARPi sensitivity