Nociceptin Signals Through Calcium in \u3ci\u3eTetrahymena thermophila\u3c/i\u3e

Tetrahymena thermophila are free-living, ciliated, eukaryotic organisms that respond to stimuli by moving toward chemoattractants and avoiding chemorepellents. Chemoattractant responses involve faster ciliary beating, which propels the organisms forward more rapidly. Chemorepellents signaling involves ciliary reversal, which disrupts forward swimming, and causes the organisms to jerk back and forth, swim in small circles, or spin in an attempt to get away from the repellent. Many food sources, such as proteins, are chemoattractants for these organisms, while a variety of compounds are repellents. Repellents in nature are thought to come from the secretions of predators, or from ruptured organisms, which may serve as danger signals. Interestingly, several hormones involved in human pain signaling have been shown to be chemorepellents in Tetrahymena, including substance P, ACTH, PACAP, VIP, and nociceptin. Recently, we have been studying Tetrahymena response to nociceptin, using pharmacological inhibitors in order to elucidate components of the nociceptin signaling pathway. We have found that G-protein inhibitors and a number of mammalian tyrosine kinase inhibitors have no effect on nociceptin avoidance. However, the tyrosine kinase inhibitor, genistein, inhibits avoidance to nociceptin. Nociceptin avoidance is also inhibited by the calcium chelator, EGTA, which implicates calcium in the avoidance response. Electrophysiology studies done in a calcium-containing buffer show that 50 μM nociceptin causes a sustained depolarization of approximately 30 mV, further supporting the hypothesis that calcium is involved in nociceptin signaling. J-113397, an inhibitor of the human nociceptin receptor, also inhibits nociceptin avoidance in Tetrahymena. We are currently working to determine whether other inhibitors of the human nociceptin receptor have any effect on Tetrahymena, in order to get a more complete picture of the signaling pathway

Does Target Race Moderate the Effect of Trustworthiness on Face Memory?

Multiple factors can influence how accurately people remember the faces of others. Social group membership, and particularly race, is a well-studied influence. People tend to show better memory for racial ingroup faces than racial outgroup faces, a phenomenon known as the Cross Race Effect. Some other work has examined the influence of factors like facial trustworthiness in memory, finding that people may remember untrustworthy faces more accurately than trustworthy faces. The present study examines the joint influence of these two factors in order to determine whether target race moderates this untrustworthiness advantage in memory. White and Black participants encoded an equal amount of trustworthy and untrustworthy White and Black male faces. Although both participant groups accurately remembered ingroup untrustworthy faces better than trustworthy ones, only Black participants showed an untrustworthiness advantage for outgroup faces. Among White participants, this untrustworthiness advantage was limited to ingroup faces. These findings have implications for existing theory on appearance-based influences on face memory