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Cognition from genes to ecology: individual differences incognition and its potential role in a social network
There have now been many reports of intra-colony differences in how individuals learn on a variety of conditioning tasks in both honey bees and bumble bees. Yet the fundamental mechanistic and adaptive bases for this variation have yet to be fully described. This review summarizes a long series of investigations with the honey bee (
Apis mellifera
) that had the objective of describing the factors that contribute to this variation. Selection on haploid drones for extremes in learning performance revealed that genotype accounted for much of the variance. Neither age nor behavioral caste consistently accounted for observed variation on different conditioning protocols until genotype was controlled. Two subsequent Quantitative Trait Locus mapping studies identified a locus in the honey bee genome with a significant effect on the learning phenotype. Pharmacological and reverse genetic approaches, combined with neurophysiological analyses, confirmed that a biogenic amine receptor for tyramine affects expression of the trait. This work allowed for development of a hypothetical model of how that receptor functions in the brain to produce broad pleiotropic effects on behavior. Subsequent work used genotype as a treatment condition for evaluation of the variation under quasi-natural conditions, which revealed that individual variation reflects how foragers weigh known and novel resources in decision making. This work, together with other studies of individual differences, suggests a unifying framework for understanding how and why individuals differ in cognitive abilities.
Journal Article
Rapid removal of organic micropollutants from water by a porous β-cyclodextrin polymer
An alternative material to activated carbon for water remediation is reported: a porous material based on crosslinked cyclodextrins that is better than activated carbons at adsorbing a range of pharmaceuticals, pesticides and other anthropogenic pollutants.
Near-instant removal of organic micropollutants from water
Water purification and remediation is often carried out using various forms of activated carbon; it is inexpensive, but only partially removes many organic pollutants. However, regenerating activated carbon for reuse is energy intensive, requiring high temperatures, and performance decreases upon recycling. Now William Dichtel, Damian Helbling and colleagues have developed an alternative to activated carbon for water remediation: a high-surface-area, mesoporous polymer of β-cyclodextrin. Not only does the material outperform activated carbons at adsorbing a range of pharmaceuticals, pesticides and other pollutants, but it is easily regenerated by washing at room temperature.
The global occurrence in water resources of organic micropollutants, such as pesticides and pharmaceuticals, has raised concerns about potential negative effects on aquatic ecosystems and human health
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. Activated carbons are the most widespread adsorbent materials used to remove organic pollutants from water but they have several deficiencies, including slow pollutant uptake (of the order of hours)
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and poor removal of many relatively hydrophilic micropollutants
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. Furthermore, regenerating spent activated carbon is energy intensive (requiring heating to 500–900 degrees Celsius) and does not fully restore performance
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. Insoluble polymers of β-cyclodextrin, an inexpensive, sustainably produced macrocycle of glucose, are likewise of interest for removing micropollutants from water by means of adsorption
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. β-cyclodextrin is known to encapsulate pollutants to form well-defined host–guest complexes, but until now cross-linked β-cyclodextrin polymers have had low surface areas and poor removal performance compared to conventional activated carbons
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. Here we crosslink β-cyclodextrin with rigid aromatic groups, providing a high-surface-area, mesoporous polymer of β-cyclodextrin. It rapidly sequesters a variety of organic micropollutants with adsorption rate constants 15 to 200 times greater than those of activated carbons and non-porous β-cyclodextrin adsorbent materials
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. In addition, the polymer can be regenerated several times using a mild washing procedure with no loss in performance. Finally, the polymer outperformed a leading activated carbon for the rapid removal of a complex mixture of organic micropollutants at environmentally relevant concentrations. These findings demonstrate the promise of porous cyclodextrin-based polymers for rapid, flow-through water treatment.
Journal Article
Hyperbolic odorant mixtures as a basis for more efficient signaling between flowering plants and bees
Animals use odors in many natural contexts, for example, for finding mates or food, or signaling danger. Most analyses of natural odors search for either the most meaningful components of a natural odor mixture, or they use linear metrics to analyze the mixture compositions. However, we have recently shown that the physical space for complex mixtures is ‘hyperbolic’, meaning that there are certain combinations of variables that have a disproportionately large impact on perception and that these variables have specific interpretations in terms of metabolic processes taking place inside the flower and fruit that produce the odors. Here we show that the statistics of odorants and odorant mixtures produced by inflorescences ( Brassica rapa ) are also better described with a hyperbolic rather than a linear metric, and that combinations of odorants in the hyperbolic space are better predictors of the nectar and pollen resources sought by bee pollinators than the standard Euclidian combinations. We also show that honey bee and bumble bee antennae can detect most components of the B . rapa odor space that we tested, and the strength of responses correlates with positions of odorants in the hyperbolic space. In sum, a hyperbolic representation can be used to guide investigation of how information is represented at different levels of processing in the CNS.
Journal Article
Understanding Third World politics : theories of political change and development
\"A comprehensive, critical introduction to key political theories and controversies in international development for students in Third World politics, political and economic development, and comparative government courses. B.C. Smith reviews the shared and increasingly diverse experiences of developing societies, debates about the nature of imperialism, and the usefulness and limitations of the term 'Third World' as an organizing concept. He evaluates explanations of political change and theorizes the character and dynamics of political institutions and the instabilities they face today.\"--Amazon.com.
Book
Current Trends in Sirtuin Activator and Inhibitor Development
Sirtuins are NAD+-dependent protein deacylases and key metabolic regulators, coupling the cellular energy state with selective lysine deacylation to regulate many downstream cellular processes. Humans encode seven sirtuin isoforms (Sirt1-7) with diverse subcellular localization and deacylase targets. Sirtuins are considered protective anti-aging proteins since increased sirtuin activity is canonically associated with lifespan extension and decreased activity with developing aging-related diseases. However, sirtuins can also assume detrimental cellular roles where increased activity contributes to pathophysiology. Modulation of sirtuin activity by activators and inhibitors thus holds substantial potential for defining the cellular roles of sirtuins in health and disease and developing therapeutics. Instead of being comprehensive, this review discusses the well-characterized sirtuin activators and inhibitors available to date, particularly those with demonstrated selectivity, potency, and cellular activity. This review also provides recommendations regarding the best-in-class sirtuin activators and inhibitors for practical research as sirtuin modulator discovery and refinement evolve.
Journal Article
Between-Hospital Variation in Treatment and Outcomes in Extremely Preterm Infants
Among hospitals in the NICHD Neonatal Research Network, rates of active treatment of infants born at 22 to 24 weeks of gestation varied substantially and accounted for a substantial proportion of between-hospital variation in overall survival and survival without impairment.
The decision to initiate or forgo potentially lifesaving treatment in infants who are born near the limit of viability is extremely difficult.
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Clinicians recognize that in some cases, the infant is too immature for treatment to be effective, whereas in other cases, treatment is clearly indicated. Yet, in many cases, it is unclear whether treatment is in the infant’s best interest.
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Although factors such as the infant’s birth weight and sex, plurality of birth (singleton vs. multiple), and exposure to antenatal glucocorticoids affect the prognosis of extremely preterm infants,
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many groups still make recommendations about active treatment . . .
Journal Article