Olfactory basis of cannibalism in grasshoppers (Orthoptera: Acididae): I. laboratory assessment of attractants

Two laboratory-reared and five field-collected species of grass-hoppers were assayed for behavioral responses to volatile chemicals emitted from grasshopper cadavers using a two-choice olfactometer with no stimulus as a control. Necrophilic and necrophobic responses to the stimuli were dependent upon species, sex, development, starvation, crowding, and attractant. Laboratory-rearedMelanoplus differentialis (Thomas) and field-collectedHadrotettix trifasciatus (Say) andAulocara elliotti Thomas exhibited significant responses to the cadavers. Females of these three species showed significant movement towards the cadavers, but males were not significantly necrophilic. All tested developmental stages ofH. trifasciatus (fourth-instar nymphs through adults) showed significant attraction to cadavers. FedM. differentialis adults andH. trifasciatus adults and nymphs were significantly attracted to cadavers, but starved individuals were either repelled or exhibited no significant response. Although femaleA. elliotti from an uncrowded population were significantly attracted to cadavers, females from a crowded population were significantly repelled from cadavers. Contraspecific cadavers more frequently elicited a measurable response in adultM. sanguinipes andH. trifasciatus than did conspecific cadavers, and only contraspecific cadavers yielded a significant (necrophilic) response. AlthoughM. differentialis was necrophilic, neither males nor females were significantly attracted to water.     

Whey protein-derived exosomes increase protein synthesis and hypertrophy in C2­C12 myotubes

We sought to examine potential amino acid independent mechanisms whereby hydrolyzed whey protein (WP) affects muscle protein synthesis (MPS) and anabolism in vitro. Specifically, we tested (1) whether 3-h and 6-h treatments of WP, essential amino acids, or l-leucine (Leu) affected MPS, and whether 6-h treatments with low-, medium-, or high doses of WP versus Leu affected MPS; (2) whether knockdown of the primary Leu transporter affected WP- and Leu-mediated changes in MPS, mammalian target of rapamycin (mTOR) signaling responses, or both, following 6-h treatments; (3) whether exosomes isolated from WP (WP-EXO) affected MPS, mTOR signaling responses, or both, compared with untreated (control) myotubes, following 6-h, 12-h, and 24-h treatments, and whether they affected myotube diameter following 24-h and 48-h treatments. For all treatments, 7-d post-differentiated C₂C₁₂ myotubes were examined. In experiment 1, 6-h WP treatments increased MPS compared with control (+46%), Leu (+24%), and essential amino acids (+25%). Moreover, the 6-h low-, medium-, and high WP treatments increased MPS by approximately 40 to 50% more than corresponding Leu treatments. In experiment 2 (LAT short hairpin RNA-transfected myotubes), 6-h WP treatments increased MPS compared with control (+18%) and Leu (+19%). In experiment 3, WP-EXO treatments increased MPS over controls at 12 h (+18%) and 24 h (+45%), and myotube diameters increased with 24-h (+24%) and 48-h (+40%) WP-EXO treatments compared with controls. The WP-EXO treatments did not appear to operate through mTOR signaling; instead, they increased mRNA and protein levels o eukaryotic initiation factor 4A. Bovine-specific microRNA following 24-h WP-EXO treatments were enriched in myotubes (chiefly miR-149-3p, miR-2881), but were not related to hypertrophic gene targets. To summarize, hydrolyzed WP-EXO increased skeletal MPS and anabolism in vitro, and this may be related to an unknown mechanism that increases translation initiation factors rather than enhancing mTOR signaling or the involvement of bovine-specific microRNA.     

For better and for worse: Everyday social comparisons between romantic partners.

The authors examined the frequency, direction, and impact of social comparisons between romantic partners. Comparisons were expected to occur on a daily basis, owing to regular interactions between partners. To the extent that one empathizes and shares outcomes with one's partner, one might respond more positively to upward than to downward comparisons. Study 1a was an experience-sampling study in which participants reported comparisons made to their spouse over 2 weeks. Study 1b examined reactions to the most significant comparisons made during the experience-sampling study. Participants reported making comparisons to their romantic partner more than once a day on average and experienced more positive responses to upward than to downward comparisons. Study 2 demonstrated that participants empathized and shared outcomes with their partner to a greater extent than with a friend. Study 3 confirmed that participants responded more positively to upward than to downward comparisons even for domains high in self-relevance and even when the comparison had negative self-evaluative implications. These results suggest that, owing to higher levels of empathy and shared fate with partners, comparisons function differently in romantic than in other relationships. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Cover Picture: Thermotropic Liquid Crystals as Substrates for Imaging the Reorganization of Matrigel by Human Embryonic Stem Cells (Adv. Funct. Mater. 5/2006)

New approaches to the culture of cells and measurements of cell–extracellular‐matrix interactions are suggested in the Full Paper by Abbott and co‐workers on p. 618. The culture of human embryonic stem cells (hESCs) on interfaces of a thermotropic liquid crystal that are decorated with thin films of the extracellular matrix, Matrigel, are investigated. The cover image shows the polarized light microscopy image of hESCs cultured for three days on a Matrigel‐coated film of liquid crystal hosted within a TEM grid. The hESCs reorganized the Matrigel, leading to patterned orientations of the liquid crystal. We have investigated the culture of human embryonic stem cells (hESCs) on interfaces of the thermotropic liquid crystal, TL205, that are decorated with thin films of the extracellular matrix, Matrigel. hESCs seeded at the liquid‐crystal/Matrigel interface survive for weeks, and cell colonies grow over this time. The cells show levels of differentiation comparable to that observed for cells on Matrigel‐coated glass controls. Polarized and fluorescence microscopy reveal that the orientational order of the liquid crystal is coupled to the presence and organization of Matrigel. This enables straightforward imaging of the reorganization of Matrigel by the hESCs through changes in the appearance of the liquid crystal when observed using polarized light microscopy. The coupling between Matrigel and TL205 thus provides a simple tool for monitoring the reorganization of the Matrigel film over time. Our results suggest new approaches to the culture of cells and measurements of cell–extracellular‐matrix interactions.     

Thermal stability of direct dental esthetic restorative materials at elevated temperatures

With increasing use of direct esthetic restorative materials, the identity of a body may rely upon knowledge of temperature effects on this class of dental restorations. This research examined the effect of atmospheric gas on thermal decomposition and color change of a wide variety of direct esthetic restorative materials. Cured discs (4 x 1 and 8 x 1 mm) were made using manufacturer's directions: traditional glass ionomer (Fuji II), light-curable resonomer (Fuji II LC), compomer (Geristore), and three types of resin composites--highly filled, urethane-based (Occlusin), and two Bis-GMA/TEGDMA resins: hybrid (Herculite XRV) and microfill (Silux Plus). Three replications of each material were heated at 5 degrees C/min in a thermogravimetric analysis unit using either room air or nitrogen purge to simulate different thermal environments. First derivative values of percent weight loss with respect to temperature were obtained to determine temperatures associated with increased decomposition rates. Room-air heating showed greater numbers of decomposition events than did nitrogen-heated discs. The only material decomposing less than 200 degrees C in either atmosphere was traditional glass ionomer. The majority of decomposition occurred between 200 degrees and 500 degrees C for all materials. Only products containing glass ionomer components decomposed between 600 degrees and 800 degrees C. Room-air heating resulted in ash white discs at 800 degrees C and higher. Specimens heated in nitrogen were gray to black at 600 degrees C and higher. Heating atmosphere greatly affected color, and some products demonstrated distinguishing color changes: glass ionomers, in particular, showed characteristic color features. An atlas was constructed from color change of specimens recovered after 200 degrees, 400 degrees, 600 degrees, 800 degrees, and 1000 degrees C compared with non-heated controls.     

A Decaheme Cytochrome as a Molecular Electron Conduit in Dye‐Sensitized Photoanodes

In nature, charge recombination in light‐harvesting reaction centers is minimized by efficient charge separation. Here, it is aimed to mimic this by coupling dye‐sensitized TiO₂ nanocrystals to a decaheme protein, MtrC from Shewanella oneidensis MR‐1, where the 10 hemes of MtrC form a ≈7‐nm‐long molecular wire between the TiO₂ and the underlying electrode. The system is assembled by forming a densely packed MtrC film on an ultra‐flat gold electrode, followed by the adsorption of approximately 7 nm TiO₂ nanocrystals that are modified with a phosphonated bipyridine Ru(II) dye (RuP). The step‐by‐step construction of the MtrC/TiO₂ system is monitored with (photo)electrochemistry, quartz‐crystal microbalance with dissipation (QCM‐D), and atomic force microscopy (AFM). Photocurrents are dependent on the redox state of the MtrC, confirming that electrons are transferred from the TiO₂ nanocrystals to the surface via the MtrC conduit. In other words, in these TiO₂/MtrC hybrid photodiodes, MtrC traps the conduction‐band electrons from TiO₂ before transferring them to the electrode, creating a photobioelectrochemical system in which a redox protein is used to mimic the efficient charge separation found in biological photosystems.