Empirical Evidence on Repeated Sequential Games

Sequentiality of moves in an infinitely repeated prisoner’s dilemma does not change the conditions under which mutual cooperation can be supported in equilibrium as compared to simultaneous decision-making. The nature of the interaction is different, however, given that the second mover in a sequential-move game does not face strategic uncertainty in the stage game. We study in an experiment whether sequentiality has an effect on cooperation rates. We find that with intermediate incentives to cooperate, sequentiality increases cooperation rates by around 40 percentage points after learning, whereas with very low or high incentives to cooperate, cooperation rates are respectively very low or high in both settings

Two glycosphingolipid sialyltransferases are localized in different sub-Golgi compartments in rat liver

A highly purified Golgi preparation from rat liver was fractionated on a sucrose density gradient and the activity of two sialyltransferases, CMP-NeuAc: Galβ1→4Glc-Cer (lactosylceramide) α-2→3sialyltransferase; Sat-1), and CMP-NeuAc: Galβ1→3GalNAcβ1→4(NeuAcα2→3)Galβ1→4Glc-Cer (GM1 ganglioside) α2 →3sialyltransferase; SAT-4), involved in the biosynthesis of gangliosides were assayed in the collected fractions. These two activities were recovered in different regions of the gradient; SAT-1 was found in a more dense region than SAT-4. This distribution coincided with that of two N-Asn linked oligosaccharide processing enzymes (UDP-GlcNAc:lysosomal enzyme precursor GlcNAc-1-phosphotransferase and UDP-Gal:ovalbumin galactosyltransferase), assumed as putative markers of eis- and trans-Golgi cisternae, respectively. These findings are consistent with the assembly of ganglioside oligosaccharide chains occurring in different sub-Golgi compartments

Topography of glycosyltransferases involved in the initial glycosylations of gangliosides.

We attempted to establish within which organelle UDP-Glc:ceramide beta 1----1'glucosyltransferase (GlcT) is located and moreover to obtain information about its orientation on intracellular membranes as well as that of UDP-Gal:glucosylceramide beta 1----4galactosyltransferase (GalT-2) and CMP-NeuAc:lactosylceramide alpha 2----3sialyltransferase (SAT-1). An extremely purified Golgi apparatus fraction was the only liver fraction where a ceramide-dependent formation of glucosylceramide could be demonstrated. This Golgi fraction, mainly constituted by stacks of intact cisternae which retained the same topographical orientation as in vivo, was then incubated with liposomal dispersions of glycosphingolipid-glycosyltransferase acceptors in reaction mixtures containing all the requirements for enzyme activity but no detergent. Under such conditions, SAT-1 and other late acting glycosyltransferases were over 90% latent, while both GlcT and GalT-2 were just as active as in the detergent-containing assay; they were still inhibited by EDTA. Sepharose-immobilized ceramide and Sepharose-immobilized glucosylceramide were found to be suitable acceptors for GlcT and GalT-2, respectively, still using intact Golgi cisternae as the enzyme source. Moreover, a part of GlcT and GalT-2 activity was released from intact Golgi cisternae upon cathepsin D treatment. These results provide strong evidence that GlcT and GalT-2 face the cytoplasmic side of the Golgi apparatus, whereas SAT-1 and the other late acting enzymes face the luminal side

Carbon is Forever: a Climate Change Experiment on Cooperation

Greenhouse gases generate impacts that can last longer than human civilization itself. Such persistence may affect the behavioral ability to cooperate. Here we study mitigation efforts within a framework that reflects key features of climate change and then contrasts a dynamic versus a static setting. In a treatment with persistence, the pollution cumulates and generates damages over time while in another treatment it has only immediate effects and then disappears. We find that cooperation is not hampered, on average, by pollution persistence. Mitigation efforts, though, should not be delayed, because cooperation levels appear to deteriorate for high stocks of pollution

A PART OF GLUCOSYLCERAMIDE FORMED FROM EXOGENOUS LACTOSYLCERAMIDE IS NOT DEGRADED TO CERAMIDE BUT RE-CYCLED AND GLYCOSYLATED IN THE GOLGI APPARATUS

Abstract The subcellular fate of glucosylceramide (GlcCer) formed from exogenous lactosylceramide (LacCer) in rat liver is investigated. LacCer radiolabeled on different positions of the molecule was intravenously administered to rats as a liposomal dispersion. A Golgi apparatus fraction 140-fold enriched in specific markers and constituted by intact cisternal stacks, as well as the lysosomal and plasma membrane fractions concurrently prepared from the same homogenate, were then studied in order to determine the time course of radioactive glycosphingolipids. LacCer quickly decreased with time in the plasma membrane, whereas in the lysosomes it increased up to 4 h and decreased thereafter. In both fractions results were regardless of the labeling position. In the Golgi apparatus, LacCer increased up to 12 h and then decreased. In this fraction, the radioactivity values of [Glc-3H]LacCer were over twice those of [Gal-3H]LacCer. GlcCer was found only after [Glc-3H]LacCer administration. In the lysosomes, its time course provided a peak similar in shape but delayed in timing with respect to that of LacCer. Conversely, in the Golgi apparatus GlcCer was earlier formed, but earlier consumed, than LacCer. Gangliosides increased in the Golgi apparatus until 4 h and then decreased after 12 h, whereas in the plasma membrane they were progressively accumulated. In both fractions the amount of [Glc-3H]gangliosides was over twice that of [Gal-3H]gangliosides was over twice that of [Gal-3H]gangliosides. Since we demonstrated that the sugars released in the course of LacCer degradation (LacCer----galactose + GlcCer----glucose + ceramide) are not incorporated into glycoconjugates, we conclude that a part of GlcCer formed during the lysosomal degradation of LacCer actually reaches the Golgi apparatus where it undergoes successive glycosylation

Sub-Golgi distribution in rat liver of CMP-NeuAc GM3- and CMP-NeuAc:GT1b alpha 2----8sialyltransferases and comparison with the distribution of the other glycosyltransferase activities involved in ganglioside biosynthesis.

Using a sucrose density gradient fractionation of a highly purified Golgi apparatus from rat liver, we determined the sub-Golgi distribution of CMP-NeuAc:GM3 ganglioside alpha 2----8sialyltransferase (GM3-SAT) and CMP-NeuAc:GT1b ganglioside alpha 2----8sialyltransferase (GT1b-SAT), in comparison with that of the other glycosyltransferase activities involved in ganglioside biosynthesis. While GM3-SAT was recovered in several density fractions, GT1b-SAT was mainly found on less dense sub-Golgi membranes; this indicates that these two activities are physically separate. Moreover, with regard to the monosialo pathway, CMP-NeuAc:lactosylceramide alpha 2----3sialyltransferase, UDP-GalNAc:GM3 ganglioside beta 1----4N-acetylgalactosaminyltransferase, UDP-Gal:GM2 ganglioside beta 1----3galactosyltransferase, and CMP-NeuAc:GM1 ganglioside alpha 2----3sialyltransferase were resolved from more dense to less dense fractions, respectively. In the disialo pathway, UDP-GalNAc:GD3 ganglioside beta 1----4N-acetylgalactosaminyltransferase, UDP-Gal:GD2 ganglioside beta 1----3galactosyltransferase and CMP-NeuAc:GD1b ganglioside alpha 2----3sialyltransferase co-distributed with the corresponding activities of the monosialo pathway. These last results indicate that many Golgi glycosyltransferases involved in ganglioside biosynthesis are localized in the order in which they act

Experiments on Pro-Sociality and Environmental Issues

The thesis comprises three essays that use experimental methods, one about other-regarding motivations in economic behavior and the others on pro-social behavior in two environmental economics problems. The first chapter studies how the expectations of the others and the concern to maintain a balance between effort exerted and rewards obtained interact in shaping the behavior in a modified dictator game. We find that dictators condition their choices on recipients' expectations only when there is a high probability that the the recipient will not be compensated for her effort. Otherwise, dictators tend to balance the efforts and rewards of the recipients, irrespective of the recipients' expectations. In the second chapter, I investigate the problem of local opposition to large public projects (e.g. landfills, incinerators, etc.). In particular, the experiment shows how the uncertainty about the project's quality makes the community living in the host site skeptical about the project. I also test whether side-transfers and costly information disclosure can help to increase the efficiency. Both tools succesfully make the host more willing to accept the project, but they lead to the realization of different types of projects. The last chapter is an experiment on climate negotiations. To avoid the global warming, countries are called to cooperate in the abatement of their emissions. We study whether the dynamic aspect of the climate change makes cooperation across countries behaviorally more difficult. We also consider inequality across countries as a possible factor that hinders international cooperation

Exposure to Ethnic Minorities Changes Attitudes to Them

Does exposure to ethnic minorities change the majority’s attitudes towards them? We investigate this question using novel panel data on attitudes from a general-population sample in the Netherlands matched to geographical data on refugees. We find that people who live in neighborhoods of refugees for a sufficiently long time acquire a more positive attitude. Instead, people living in municipalities hosting refugees, but not in their close neighborhood, develop a more negative attitude. The positive neighborhood effect is particularly strong for groups that are likely to have personal contact with refugees suggesting that contact with minorities can effectively reduce prejudice