Gradual Translocation of Spatial Correlates of Neuronal Firing in the Hippocampus toward Prospective Reward Locations

SummaryIn a continuous T-maze alternation task, CA1 complex-spike neurons in the hippocampus differentially fire as the rat traverses overlapping segments of the maze (i.e., the stem) repeatedly via alternate routes. The temporal dynamics of this phenomenon were further investigated in the current study. Rats learned the alternation task from the first day of acquisition and the differential firing pattern in the stem was observed accordingly. More importantly, we report a phenomenon in which spatial correlates of CA1 neuronal ensembles gradually changed from their original firing locations, shifting toward prospective goal locations in the continuous T-maze alternation task. The relative locations of simultaneously recorded firing fields, however, were preserved within the ensemble spatial representation during this shifting. The within-session shifts in preferred firing locations in the absence of any changes in the environment suggest that certain cognitive factors can significantly alter the location-bound coding scheme of hippocampal neurons

Geologic studies to identify the source for high levels of radium and barium in Illinois ground-water supplies: a preliminary report

Analyses of water from municipal wells in Illinois by the Illinois Environmental Protection Agency showed that more than 300 wells exceeded the upper limit, 3 picocuries/liter (U.S. Public Health Service, 1962), for gross alpha radiation in drinking water. More than 30 wells exceeded the upper limit, 1 milligram/liter (U.S. Public Health Service, 1962), for barium in drinking water. High levels of radiation in ground water were more extensive in areal distribution than the high levels of barium. All of the affected wells were finished in bedrock, primarily in rocks of the Cambrian and Ordovician Systems of northern Illinois. The geologic settings in which the high levels of radiation and barium were documented indicated that the problem was not restricted to Illinois.The source of the radiation in ground water was thought to be the natural occurrence of the radioactive elements.uranium-238 and thorium-232 in the aquifer rocks. Analyses of a limited number of rock samples indicated that uranium and thorium concentrations were highest in fine-grained sediments in the aquifer systems; the highest concentration was in shales that confine the aquifer.The occurrence of natural radioisotopes in ground water was thought to be complex, involving source rocks, ground water chemistry, and the hydraulic stress placed on the aquifer.Chemical analyses of rock samples indicated that high concentrations of barium were widespread in rocks of the Cambrian and Ordovician Systems. The concentration of barium in ground water was controlled by solubility equilibria reactions with sulfate ion. A map showing sulfate ion concentration in the Cambrian-Ordovician Aquifer could be used to delimit regions where barium might occur at concentrations exceeding 1 milligram/liter.U.S. Department of the InteriorU.S. Geological Surve

A metabolomic strategy defines the regulation of lipid content and global metabolism by Δ9 desaturases in Caenorhabditis elegans.

BACKGROUND: Caenorhabditis elegans provides a genetically tractable model organism to investigate the network of genes involved in fat metabolism and how regulation is perturbed to produce the complex phenotype of obesity. C. elegans possess the full range of desaturases, including the Δ9 desaturases expressed by fat-5, fat-6 and fat-7. They regulate the biosynthesis of monounsaturated fatty acids, used for the synthesis of lipids including phospholipids, triglycerides and cholesteryl esters. RESULTS: Liquid chromatography mass spectrometry (LC-MS), gas chromatography mass spectrometry (GC-MS) and nuclear magnetic resonance (NMR) spectroscopy were used to define the metabolome of all the possible knock-outs for the Δ9 desaturases, including for the first time intact lipids. Despite the genes having similar enzymatic roles, excellent discrimination was achievable for all single and viable double mutants highlighting the distinctive roles of fat-6 and fat-7, both expressing steroyl-CoA desaturases. The metabolomic changes extend to aqueous metabolites demonstrating the influence Δ9 desaturases have on regulating global metabolism and highlighting how comprehensive metabolomics is more discriminatory than classically used dyes for fat staining. CONCLUSIONS: The propagation of metabolic changes across the network of metabolism demonstrates that modification of the Δ9 desaturases places C.elegans into a catabolic state compared with wildtype controls.RIGHTS : This article is licensed under the BioMed Central licence at http://www.biomedcentral.com/about/license which is similar to the 'Creative Commons Attribution Licence'. In brief you may : copy, distribute, and display the work; make derivative works; or make commercial use of the work - under the following conditions: the original author must be given credit; for any reuse or distribution, it must be made clear to others what the license terms of this work are

Semiclassical Corrections to a Static Bose-Einstein Condensate at Zero Temperature

In the mean-field approximation, a trapped Bose-Einstein condensate at zero temperature is described by the Gross-Pitaevskii equation for the condensate, or equivalently, by the hydrodynamic equations for the number density and the current density. These equations receive corrections from quantum field fluctuations around the mean field. We calculate the semiclassical corrections to these equations for a general time-independent state of the condensate, extending previous work to include vortex states as well as the ground state. In the Thomas-Fermi limit, the semiclassical corrections can be taken into account by adding a local correction term to the Gross-Pitaevskii equation. At second order in the Thomas-Fermi expansion, the semiclassical corrections can be taken into account by adding local correction terms to the hydrodynamic equations

Use of alternative time scales in Cox proportional hazard models: implications for time-varying environmental exposures

Issues surrounding choice of time scales in Cox proportional hazard regression models have received limited attention in the literature. Although the choice between time on study and ‘attained’ age time scales has been examined, the calendar time scale may be of interest when modeling health effects of environmental exposures with noteworthy secular trends such as ambient particulate matter air pollution in large epidemiological cohort studies. The authors use simulation studies to examine performance (bias, mean squared error, coverage probabilities, and power) of models using all three time scales when the primary exposure of interest depends on calendar time. Results show that performance of models fit to the calendar time scale varies inversely with the strength of the linear association between the time-varying primary exposure and calendar time. Although models fit to attained age and time on study that do not adjust for calendar time were relatively robust, the authors conclude that care should be exercised when using time scales that are highly correlated with exposures of interest

How Comprehensive and Efficient Are Patient-Reported Outcomes for Rotator Cuff Tears?

BACKGROUND: Increasing emphasis is placed on patient-reported outcomes (PROs) after common orthopaedic procedures as a measure of quality. When considering PRO utilization in patients with rotator cuff tears, several different PROs exist with varying levels of accuracy and utilization. HYPOTHESIS/PURPOSE: Understanding which disease-specific PRO may be most efficiently administered in patients after rotator cuff repair may assist in promoting increased patient and physician adoption of these useful scores. Using a novel assessment criterion, this study assessed all commonly used rotator cuff PROs. We hypothesize that surveys with fewer numbers of questions may remain comparable (with regard to comprehensiveness) to longer surveys. STUDY DESIGN: Systematic review. METHODS: Commonly utilized rotator cuff PROs were analyzed with regard to number of survey components, comprehensiveness, and efficiency. Comprehensiveness (maximum score, 11) was scored as the total number of pain (at rest/baseline, night/sleep, activities of daily living [ADLs], sport, and work) and functional (strength, motion/stiffness, and ability to perform ADLs, sport, and work) metrics included, along with inclusion of quality of life/satisfaction metrics. Efficiency was calculated as comprehensiveness divided by the number of survey components. RESULTS: Sixteen different PROs were studied. Number of components ranged from 5 (University of California at Los Angeles score [UCLA]) to 36 (Short Form-36 [SF-36], Japanese Orthopaedic Association score [JOA]). The Quality of Life Outcome Measure for Rotator Cuff Disease (RC-QoL) included all 5 pain components, while 7 PROs contained all 5 functional components. Ten PROs included a quality of life/satisfaction component. The most comprehensive scores were the RC-QoL (score, 11) and Penn (score, 10), and the least comprehensive score was the Marx (score, 3). The most efficient PROs were the UCLA, the Quick Disabilities of the Arm, Shoulder, and Hand score (QuickDASH), and Constant scores. The least efficient scores were the JOA and SF-36 scores. CONCLUSION: Many commonly utilized PROs for rotator cuff tears are lacking in comprehensiveness and efficiency. Continued critical assessment of PRO quality may help practitioners identify the most comprehensive and efficient PRO to incorporate into daily clinical practice

DNA Persistence in Predator Saliva from Multiple Species and Methods for Optimal Recovery from Depredated Carcasses

Molecular forensics is an important component of wildlife research and management. Using DNA from noninvasive samples collected at predation sites, we can identify predator species and obtain individual genotypes, improving our understanding of predator–prey dynamics and impacts of predators on livestock and endangered species. To improve sample collection strategies, we tested two sample collection methods and estimated degradation rates of predator DNA on the carcasses of multiple prey species. We fed carcasses of calves (Bos taurus) and lambs (Ovis aires) to three captive predator species: wolves (Canis lupus), coyotes (C. latrans), and mountain lions (Puma concolor). We swabbed the carcass in the field, as well as removed a piece of hide from the carcasses and then swabbed it in the laboratory. We swabbed all tissue samples through time and attempted to identify the predator involved in the depredation using salivary DNA. We found the most successful approach for yielding viable salivary DNA was removing hide from the prey and swabbing it in the laboratory. As expected, genotyping error increased through time and our ability to obtain complete genotypes decreased over time, the latter falling below 50% after 24 h. We provide guidelines for sampling salivary DNA from tissues of depredated carcasses for maximum probability of detection

Conflict of interest and signal interference lead to the breakdown of honest signalling

Animals use signals to coordinate a wide range of behaviours, from feeding offspring to predator avoidance. This poses an evolutionary problem, because individuals could potentially signal dishonestly to coerce others into behaving in ways that benefit the signaller. Theory suggests that honest signalling is favoured when individuals share a common interest and signals carry reliable information. Here, we exploit the opportunities offered by bacterial signalling, to test these predictions with an experimental evolution approach. We show that: (1) a reduced relatedness leads to the relative breakdown of signalling; (2) signalling breaks down by the invasion of mutants that show both reduced signalling and reduced response to signal; (3) the genetic route to signalling breakdown is variable; (4) the addition of artificial signal, to interfere with signal information, also leads to reduced signalling. Our results provide clear support for signalling theory, but we did not find evidence for the previously predicted coercion at intermediate relatedness, suggesting that mechanistic details can alter the qualitative nature of specific predictions. Furthermore, populations evolved under low relatedness caused less mortality to insect hosts, showing how signal evolution in bacterial pathogens can drive the evolution of virulence in the opposite direction to that often predicted by theory

Production and ecosystem structure in cold‐core vs. warm‐core eddies: Implications for the zooplankton isoscape and rock lobster larvae

Anticyclonic (warm-core) mesoscale eddies (WCEs) in the Eastern Indian Ocean carry higher surface chlorophyll signatures than cyclonic (cold-core) eddies (CCEs). Paradoxically, WCEs host rock lobster larvae (phyllosomas) with lower lipid stores and protein reserves than phyllosomas in CCEs, suggesting a poorer nutritional status. We assess primary productivity and zooplankton isotopic data from eight eddies across four research voyages (2003–2011) to determine how this contradiction might occur. We find that WCEs and CCEs are equally productive per unit chlorophyll a, but depth-integrated primary production (PP) is greater in eddies with shallower mixed layers (MLs), especially in CCEs. MLs tend to be shallower in CCEs than in WCEs because the pycnocline is closer to the surface. This, in combination with stronger stratification in CCE euphotic zones than those of WCEs, supports greater flagellate and dinoflagellate populations in CCEs. These phytoplankton provide high-quality nutrition for zooplankton, which feed on average ~ 0.6 trophic level lower in CCEs with the shallowest MLs, accumulating high lipid stores. Conversely, WCEs have, on average, ~ 70 m deeper MLs than CCEs, and host a phytoplankton community with more diatoms. Diatoms provide lower quality food for zooplankton, and zooplankton lipid stores in WCEs decline with trophic level, and possibly, with time after initial (or seasonal) nutrient injection. As a result, phyllosomas in CCEs have higher energy and lipid content than those in warm-core eddies. The resolution of the paradox, therefore, is that the higher surface chlorophyll signatures of WCEs are not representative of the nutritional value of the prey field of the phyllosoma. We also conclude that interannual variations of mixed layer depth occur at a regional scale, controlling PP