Heartbeat and Economic Decisions: Observing Mental Stress among Proposers and Responders in the Ultimatum Bargaining Game

The ultimatum bargaining game (UBG), a widely used method in experimental economics, clearly demonstrates that motives other than pure monetary reward play a role in human economic decision making. In this study, we explore the behaviour and physiological reactions of both responders and proposers in an ultimatum bargaining game using heart rate variability (HRV), a small and nonintrusive technology that allows observation of both sides of an interaction in a normal experimental economics laboratory environment. We find that low offers by a proposer cause signs of mental stress in both the proposer and the responder; that is, both exhibit high ratios of low to high frequency activity in the HRV spectrum.     

Characterization of the inhibitory effect of glucocorticoids on the DNA replication of adult rat hepatocytes growing at various cell densities

Dexamethasone inhibited the basal and EGF-stimulated DNA synthesis of adult rat hepatocytes in primary culture. The inhibition was glucocorticoid-specific: It was shown by dexamethasone and hydrocortisone, but not by progesterone, testosterone, or estradiol; and was counteracted by the glucocorticoid antagonist RU-38486 in a concentration-dependent manner. Dexamethasone acted by decreasing the rate of entry into S-phase (kG1/S), while cell cycle parameters were unaffected. The steroid was able to decrease the kG1/S severalfold even when added more than 20 hr after EGF, half-maximal effect occurring 11 hr after the addition of dexamethasone. Densely populated areas were much more sensitive to the inhibition by dexamethasone than sparsely populated areas within the same culture dish: A moderate (10 nM) concentration of dexamethasone nearly abolished the DNA synthesis in densely populated areas of hepatocyte cultures with only marginal effect on sparsely populated cells.     

Glucosinolate contents in maca (Lepidium peruvianum Chacón) seeds, sprouts, mature plants and several derived commercial products

Several products derived from processed maca hypocotyls (Lepidium peruvianum Chacón, previously known asL. meyenii Walp.) were surveyed for glucosinolate content and quantified by HPLC analysis. These included pills, capsules, flour, liquor, tonic and mayonnaise. Different plant organs such as fresh hypocotyls and leaves, seeds, dry hypocotyls, and sprouts were also included in the survey. The most abundant glucosinolates detected in fresh and dry hypocotyls and leaves were the aromatic glucosinolates, benzylglucosinolate (glucotropaeolin) and p-methoxybenzylglucosinolate. Maca seeds and sprouts differed in profile from hypocotyls and leaves due to the modification of benzylglucosinolate. No glucosinolates were detected in liquor and tonic, while mayonnaise had only trace amounts of those glucosinolates. It had instead allylglucosinolate (sinigrin), which is an aliphatic glucosinolate. The pills, capsules and flour had the same glucosinolates as those observed in hypocotyls, but in variable amounts. The richest sources of glucosinolates were seeds, fresh hypocotyls and sprouts, in that order.     

Use of regularly structured bacterial cell envelope layers as matrix for the immobilization of macromolecules

Summary Carboxyl groups present on the outer face of the hexagonally ordered S-layer lattices from Bacillus stearothermophilus PV72 and Clostridium thermohydrosulfuricum L111-69 were activated with carbodiimide. The reaction of the activated carboxyl groups with free amino groups of low molecular weight nucleophiles was controlled by labelling with polycationized ferritin, a net positively charged topographical marker for electron microscopy, which densely binds to S-layers possessing free carboxyl groups. Carbodiimide-activated carboxyl groups were also allowed to react with amino groups of ferritin (MW 440 000) and invertase (MW 270 000). Covalent attachment of ferritin was examined by electron microscopy. Using invertase, approximately 1 mg enzyme was bound per mg S-layer protein indicating a high packing density of invertase molecules on the outer face of the S-layer lattice. The immobilized invertase retained 70% of its original activity.     

Acetylcholinesterase activity in antennal receptor neurons of the sphinx moth Manduca sexta

Summary We have used a cytochemical technique to investigate the distribution of acetylcholinesterase (AChE) activity in the antenna of the sphinx moth Manduca sexta. High levels of echothiophate-insensitive (presumably intracellular) AChE activity were found in six different types of antennal receptors localized in specific regions of the three antennal segments of the adult moth. Mechanosensory organs in the scape and pedicel, the Böhm bristles and Johnston's organ, are innervated by AChE-positive neurons. In each annulus of the antennal flagellum, AChE-positive neurons are associated with six sensilla chaetica and a peg organ, probably a sensillum styloconicum. At least 112 receptor neurons (8–10 per annulus) innervating the intersegmental membranes between the 14 distalmost annuli also exhibit high levels of echothiophate-resistant AChE. In addition, each annulus has more than 30 AChE-positive somata in the epidermis of the scale-covered (back) side of the flagellum, and 4 AChE-positive somata reside within the first annulus of the flagellum. Since none of the olfactory receptor neurons show a high level of echothiophateresistant AChE activity, and all known mechanoreceptors are AChE-positive, apparently intracellular AChE activity in the antenna correlates well with mechanosensory functions and is consistent with the idea that these cells employ acetylcholine as a neurotransmitter.