Life history strategy and human cooperation in economic games

Across five studies using samples from both Japan and United States (N = 2345), we take a multi-method approach to test the prediction from life history theory that a slow, compared to fast, life history strategy promotes investment in cooperative relationships. Studies 1 and 2 examined how different measures as proxies for life history strategy (i.e., Mini-K and High-K Strategy Scale) relate to cooperation in various economic games. Studies 3 to 5 measured early childhood environments (i.e., childhood harshness and unpredictability), manipulated resource scarcity using previously validated methods, and then measured cooperation. Across our studies, we also examined four hypothesized psychological mechanisms that could explain the relation between life history strategy and cooperation: temporal discounting, concern for reputation, social value orientation, and trust in others. Overall, we found no support for the hypothesis that life history strategy predicts cooperation or that early childhood environments interact with current resource scarcity to predict cooperation. Thus, our initial findings imply that life history theory may not account for individual variation in cooperation with unknown others.     

A novel DNA polymerase inhibitor and a potent apoptosis inducer: 2-mono-O-acyl-3-O-(α-d-sulfoquinovosyl)-glyceride with stearic acid

Sulfo-glycolipids in the class of sulfoquinovosyl diacylglycerol (SQDG) including the stereoisomers are potent inhibitors of DNA polymerase α and β. However, since the α-configuration of SQDG with two stearic acids (α-SQDG-C₁₈) can hardly penetrate cells, it has no cytotoxic effect. We tried and succeeded in making a permeable form, sulfoquinovosyl monoacylglycerol with a stearic acid (α-SQMG-C₁₈) from α-SQDG-C₁₈ by hydrolysis with a pancreatic lipase. α-SQMG-C₁₈ inhibited DNA polymerase activity and was found to be a potent inhibitor of the growth of NUGC-3 cancer cells. α-SQMG-C₁₈ arrested the cell cycle at the G1 phase, and subsequently induced severe apoptosis. The arrest was correlated with an increased expression of p53 and cyclin E, indicating that α-SQMG-C₁₈ induced cell death through a p53-dependent apoptotic pathway.     

Effects of various forms of surfactant protein C on tidal volume in ventilated immature newborn rabbits.

Surfactant protein (SP)-C is characterized by alpha-helix structure and palmitoyl groups attached to two cysteine residues. We examined the function of palmitoylation and dimerization in promotion of tidal volume in immature newborn rabbits. Reconstituted surfactants were made from a mixture of synthetic phospholipids and porcine SP-B (basic mixture) by adding various forms of SP-Cs: normal SP-C isolated from porcine lungs and monomeric or dimeric forms of SP-C. These latter two were isolated from patients with pulmonary alveolar proteinosis and were less palmitoylated. Animals were ventilated at an inspiratory pressure of 25 cmH2O. Median tidal volumes were <2 ml/kg in nontreated controls, 7.7 ml/kg in animals receiving the basic mixture without SP-C, and >18 ml/kg in animals treated with reconstituted surfactants containing 3% normal or 2% dimeric SP-C (P < 0.05 vs. basic mixture). The physiological effect of basic mixture was not improved by monomeric SP-C. We conclude that palmitoyl groups are important for the physiological effects of SP-C and that the dimeric form also improves physiological effects.     

False friends are worse than bitter enemies: “Altruistic” punishment of in-group members

One of the most critical features of human society is the pervasiveness of cooperation in social and economic exchanges. Moreover, social scientists have found overwhelming evidence that such cooperative behavior is likely to be directed toward in-group members. We propose that the group-based nature of cooperation includes punishment behavior. Punishment behavior is used to maintain cooperation within systems of social exchange and, thus, is directed towards members of an exchange system. Because social exchanges often take place within groups, we predict that punishment behavior is used to maintain cooperation in the punisher's group. Specifically, punishment behavior is directed toward in-group members who are found to be noncooperators. To examine this, we conducted a gift-giving game experiment with third-party punishment. The results of the experiment (N=90) support the following hypothesis: Participants who are cooperative in a gift-giving game punish noncooperative in-group members more severely than they punish noncooperative out-group members.     

Dissociation constants of phenothiazine drugs incorporated in phosphatidylcholine bilayer of small unilamellar vesicles as determined by carbon-13 nuclear magnetic resonance spectrometric titration

The dissociation constants (pK_ms) of the phenothiazine drugs promazine, chlorpromazine, and triflupromazine, incorporated in the phosphatidylcholine (PC) bilayer of small unilamellar vesicles (SUV), were investigated by a ¹³C nuclear magnetic resonance (NMR) titration method employing their N-¹³CH₃ (ionizable group) labelled derivatives. Use of the labelled drugs enabled direct observations of the ionization equilibrium of the N-dimethyl group. A second derivative spectrophotometric study proved that 95-98% of the phenothiazine species in the sample solutions (200 μM phenothiazine in the presence of 27 mM PC SUV) were incorporated into the PC bilayer, which simplified the calculation of pK_m values by allowing that the phenothiazines in the aqueous phase could be neglected. The pK_m values were calculated from the chemical shift dependence of the N-dimethyl ¹³C NMR signal on the pH value of sample solutions. The pK_m values obtained were smaller than those measured in aqueous solutions by about one unit. The existence of cholesterol (30 mol%) in the PC bilayer showed little effect on the pK_m values, suggesting that cholesterol in the bilayer does not largely affect the interfacial region where the N-dimethyl group of the incorporated phenothiazines is located. The results offered clear evidence for the pK_m decrease and provided their precise values.     

Anticoagulant properties of a sulfated galactan preparation from a marine green alga, Codium cylindricum

An anticoagulant was isolated from a marine green alga, Codium cylindricum. The anticoagulant was composed mainly of galactose with a small amount of glucose, and was highly sulfated (13.1% as SO Na). The anticoagulant properties of the purified anticoagulant were compared with that of heparin by assays of activated partial thromboplastin time (APTT), prothrombin time (PT) and thrombin time (TT) using normal human plasma. The anticoagulant showed similar activities with heparin, however, weaker than heparin. On the other hand, the anticoagulant did not affect PT even at the concentration at which APTT and TT were strongly prolonged. The anticoagulant did not potentiate antithrombin III (AT III) and heparin cofactor II (HC II), thus the anticoagulant mechanism would be different from that of other anticoagulants isolated so far from the genus Codium.     

Immunocytochemical demonstration of the gap junction proteins connexin 43 and connexin 45 in the musculature of the rat small intestine

The immunohistochemical localization of connexin (Cx) 43 and Cx 45 in the musculature of the rat small intestine was studied at the ultrastructural level, with special reference to the interstitial cells of Cajal in the deep muscular plexus region (ICC-DMP). Cx 43 was localized at gap junctions formed between every group of cells, i.e., smooth muscle cell~smooth muscle cell, smooth muscle cell--ICC-DMP and ICC-DMP--ICC-DMP. In contrast, Cx 45 immunoreactivity was only detected at gap junctions between ICC-DMP--ICC-DMP. Since different types of Cx molecules have different properties for electrical and chemical coupling of cells, it is suggested that the homotypic network of ICC-DMP connected with Cx 45 gap junctions may function as an independent compartment segregated from the whole cellular network including the smooth muscle cells connected with Cx 43 gap junctions. It is further speculated that the ICC-DMP of the rat small intestine communicate with each other and with smooth muscle cells via the passage of messenger molecules through Cx 43, but they may use an additional mechanism, as yet unknown, for communications restricted to other ICC-DMP.     

Sequence and transcriptional studies of five clustered flagellin genes from hyperthermophilic archaeon Pyrococcus kodakaraensis KOD1

The Escherichia coli 3-ketoacyl-ACP reductase gene (fabGEc) was cloned using a PCR technique to investigate the metabolic link between fatty acid metabolism and polyhydroxyalkanoate (PHA) production. Three plasmids respectively harboring fabGEc and the poly-3-hydroxyalkanoate synthesis genes phaCAc and phaC1Ps from Aeromonas caviae and Pseudomonas sp. 61-3 respectively were constructed and introduced into E. coli HB101 strain. On a two-stage cultivation using dodecanoate as the sole carbon source, recombinant E. coli HB101 strains harboring fabGEc and phaC genes accumulated PHA copolymers (about 8 wt% of dry cell weight) consisting of several (R)-3-hydroxyalkanoate units of C4, C6, C8, and C10. It has been suggested that overexpression of the fabGEc gene leads to the supply of (R)-3-hydroxyacyl-CoA for PHA synthesis via fatty acid degradation.