This view had been based on studies which have assumed cooperation to be discrete rather than continuous

(i.e., individuals can either fully cooperate or else fully defect, but they cannot continuously vary their level of cooperation). In real world cooperation, however, cooperation is often continuous. In this paper, we re-examine the evolution of reciprocity in sizable groups by presenting a model of the n-person prisoner’s dilemma that assumes continuous rather than discrete cooperation. This model shows that continuous reciprocity has a dramatically wider basin of attraction than discrete reciprocity, and that this basin’s size increases with efficiency of cooperation (marginal per capita return). Further, we find that assortative Akt inhibitor interaction interacts synergistically with continuous reciprocity to a much greater extent than it does with discrete reciprocity. These results suggest that previous models may have underestimated reciprocity’s adaptiveness in groups. Acalabrutinib concentration However, we also find that the invasion of continuous reciprocators into a population of unconditional defectors

becomes realistic only within a narrow parameter space in which the efficiency of cooperation is close to its maximum bound. Therefore our model suggests that continuous reciprocity can evolve in large groups more easily than discrete reciprocity only under unusual circumstances. (C) 2010 Elsevier Ltd. All rights reserved.”
“13-Cis-retinoic acid (13-cis-RA) causes depression-related behavior in mice. Hypothalamic dysregulation has been implicated in clinical depression. In fact, apoptosis of hypothalamic neurons may lead AR-13324 nmr to depression after myocardial infarction. Our objective was to determine if 13-cis-RA affects cultured hypothalamic cell number. Treatment of GT1-7 hypothalamic cells with 10 mu M 13-cis-RA for 48 h decreased cell growth to 45.6 +/- 13% of control. To determine if this decrease in cell number was due to 13-cis-RA acting as an oxidant, cells were treated with I 3-cis-RA and ascorbic acid or butylated hydroxyanisole (BHA) for 24 or 48 h. Neither antioxidant alleviated the inhibitory affects

of 13-cis-RA. In addition, 13-cis-RA treatment did not increase superoxide anion production, indicating 13-cis-RA was not acting as an oxidant. To determine if 13-cis-RA was acting via retinoic acid receptors (RARs) to decrease cell number, GT1-7 cells were treated with 13-cis-RA and the RAR pan-antagonist, AGN 193109. Treatment with the RAR-antagonist blocked the ability of 13-cis-RA to decrease cell number, indicating this phenomenon was a RAR-independent mechanism. We hypothesize that the ability of I 3-cis-RA to decrease hypothalamic cell number may contribute to the increased depression-related behaviors observed in mice. (C) 2010 Elsevier Ireland Ltd and the Japan Neuroscience Society. All rights reserved.