Shifts in metabolomic profiles of the parasitoid Nasonia vitripennis associated with elevated cold tolerance induced by the parasitoid's diapause,host diapause and host diet augmented with proline

The ectoparasitoid wasp, Nasonia vitripennis can enhance its cold tolerance by exploiting a maternally-induced larval diapause. A simple manipulation of the fly host diapause status and supplementation of the host diet with proline also dramatically increase cold tolerance in the parasitoid. In this study, we used a metabolomics approach to define alterations in metabolite profiles of N. vitripennis caused by diapause in the parasitoid, diapause of the host, and augmentation of the host's diet with proline. Metabolic profiles of diapausing and nondiapausing parasitoid were significantly differentiated, with pronounced distinctions in levels of multiple cryoprotectants, amino acids, and carbohydrates. The dynamic nature of diapause was underscored by a shift in the wasp's metabolomic profile as the duration of diapause increased, a feature especially evident for increased concentrations of a suite of cryoprotectants. Metabolic pathways involved in amino acid and carbohydrate metabolism were distinctly enriched during diapause in the parasitoid. Host diapause status also elicited a pronounced effect on metabolic signatures of the parasitoid, noted by higher cryoprotectants and elevated compounds derived from glycolysis. Proline supplementation of the host diet did not translate directly into elevated proline in the parasitoid but resulted in an alteration in the abundance of many other metabolites, including elevated concentrations of essential amino acids, and reduction in metabolites linked to energy utilization, lipid and amino acid metabolism. Thus, the enhanced cold tolerance of N. vitripennis associated with proline augmentation of the host diet appears to be an indirect effect caused by the metabolic perturbations associated with diet supplementation.     

A novel 2A-peptide-containing plasmid to generate stable Perkinsus marinus cells expressing organelle-targeted genes

Genetic manipulation techniques for marine protists are not well-established, despite immense efforts. However, Perkinsus marinus is an exception and can be developed as a genetically tractable model organism for related protists. Here, we designed a new plasmid for P. marinus that allows two proteins from a single mRNA to be differently localized using a self-cleaving 2A peptide. This enabled us to establish a stable transfectant expressing a mitochondrially targeted fluorescent protein. The system can be applied to any protein in theory and would make a powerful tool for investigating unique organelles in P. marinus and related dinoflagellates.     

Selective self-synchronization of pulses in neuronal networks of the visual system

In the present study we have checked the hypothesis that the degree of pulse synchrony in neuronal pools is determined by the level of excitation of the neuronal network or its loci and that this relationship does not depend on the factor that causes the excitation. Pulse reactions of neurons in pools (2–4 cells) of cat lateral geniculate nucleus and visual cortex were registered. Neurons were excited using either visual stimuli or glutamic acid microinjections into neuronal pools. The increase of neural pool excitation level (No) regardless of the type of stimulus was shown to increase the pulse synchrony (Ns), with a correlation coefficient of 0.716 ± 0.217. One may suppose that the level of neuronal network excitation “governs” the synchrony of pulses generated by the network, i.e., neuronal networks function in compliance with the principle of self-synchronization.     

Manipulation,salience, and nudges

Cass Sunstein and Richard Thaler recommend helping people make better decisions by employing ‘nudges’, which they define as noncoercive methods of influencing choice for the better. Not surprisingly, healthcare practitioners and public policy professionals have become interested in whether nudges might be a promising method of improving health‐related behaviors without resorting to heavy‐handed methods such as coercion, deception, or government regulation. Many nudges seem unobjectionable as they merely improve the quality and quantity available for the decision‐maker. However, other nudges influence decision‐making in ways that do not involve providing more and better information. Nudges of this sort raise concerns about manipulation. This paper will focus on noninformational nudges that operate by changing the salience of various options. It will survey two approaches to understanding manipulation, one which sees manipulation as a kind of pressure, and one that sees it as a kind of trickery. On the pressure view, salience nudges do not appear to be manipulative. However, on the trickery view (which the author favors), salience nudges will be manipulative if they increase the salience so that it is disproportionate to that fact's true relevance and importance for the decision at hand. By contrast, salience nudges will not be manipulative if they merely highlight some fact that is true and important for the decision at hand. The paper concludes by providing examples of both manipulative and nonmanipulative salience nudges.     

Does the solitary parasitoid Microplitis pennatulae use a combinatorial approach to manipulate its host?

Host manipulation is a strategy used by some parasites to enhance their transmission. These parasites use a combination of neuropharmacological, psychoneuroimmunological, genomic/proteomic, or symbiont-mediated mechanisms to manipulate their hosts. Bodyguard manipulation occurs when parasitized hosts guard parasitoid pupae to protect them from their natural enemies. Bodyguard-manipulated hosts exhibit altered behaviours only after the egression of parasitoid prepupae. Behavioural changes in post-parasitoid egressed hosts could have resulted from their altered physiology. Previous studies have shown that gregarious manipulative parasitoids induce multiple physiological changes in their host, but the physiological changes induced by solitary manipulative parasitoids are unknown. Microplitis pennatulae Ranjith & Rajesh (Hymenoptera: Braconidae) is a larval parasitoid of Psalis pennatula Fabricius (Lepidoptera: Erebidae). After the egression of parasitoid prepupae, P. pennatula stops its routine activities and protects the parasitoid pupa from hyperparasitoids by body thrashes. In this study, we looked into the physiological changes induced by the solitary manipulative parasitoid, M. pennatulae, in its host, P. pennatula, during various stages of parasitization. We considered octopamine concentration and phenoloxidase (PO) activity as biomarkers of physiological change. We also examined whether M. pennatulae has a symbiotic virus and whether the wasp transfers it to the host during parasitization. We found that octopamine concentration was low in the pre-parasitoid egressed host, but it was elevated after the parasitoid egressed. Phenoloxidase activity was lower in the pre- and post-parasitoid egressed host than in the unparasitized host. We also detected symbiotic bracovirus (BV) in the wasp ovaries and isolated the BV virulence gene from the parasitised host. Our study suggests that solitary parasitoids also induce multiple physiological changes to influence the host behaviour to their advantage, as is the case with the gregarious parasitoids.     

Midbrain activity shapes high-level visual properties in the primate temporal cortex

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Hierarchical complexity of combinatorial manipulation in capuchin monkeys (Cebus apella)

The purpose of this study was to examine the hierarchical complexity of combinatorial manipulation in capuchin monkeys (Cebus apella). Two experiments were conducted. In Experiment 1 capuchins were presented with an apparatus designed to accommodate the use of probing tools. In Experiment 2 the same capuchins were presented with sets of nesting containers. Five of the ten subjects used probing tools and seven subjects placed objects in the containers. The capuchins' behavior reflected three hierarchically organized combinatorial patterns displayed by chimpanzees and human infants. Although the capuchins sometimes displayed the two more complex patterns (“pot” and “subassembly”), their combinatorial behavior was dominated by the simplest pattern (“pairing”). In this regard capuchins may not attain the same grammar of manipulative action that has been reported for chimpanzees and young human children. © 1994 Wiley-Liss, Inc.