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Pilin variation in Neisseria gonorrhoeae depends on a family of variant genes that undergo homologous, intragenic recombination. This work focuses on the repertoire of silent variant pilin genes in strain MS11, which contribute to the extensive variation of the expressed gene copy. A total of 17 silent copies were identified, which are, to varying degrees, truncated at their 5' coding region and grouped in seven distinct pil loci. Most silent copies belong to loci pilS1, pilS2 and pilS6, which contain six, two and three silent copies, respectively, tandemly arranged. The pilS5 and pilS7 loci each contain only a single copy. In addition, two silent copies are associated with each of the two pilE loci. By comparison with sequences present in the expressed gene of other variants of the same strain, it is suggested that each silent locus is capable of donating variant sequences into the expression locus and, thus, each silent copy can contribute to the variability of pilin expression. Often, concomitant with changes in the expressed copy, the silent copies of the pilE1 locus undergo recombinations as well. Analyses of unrelated clinical isolates of N. gonorrhoeae reveal homologies of hypervariant pilin sequences with those present in strain MS11, suggesting a limited diversity of such sequences within the gonococcal population and the existence of substantial functional constraints on the variability of pilin and pili. The data further indicate that hypervariant pilin sequences are subject to horizontal exchange and interstrain recombination.

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Several studies suggest a negative impact of ethnic diversity on cooperation, but most of them rely on attitudinal and other indirect measurements of cooperation or are derived from the artificial laboratory setting. We conducted a field experiment based on the lost-letter technique across 52 neighborhoods in Berlin, Germany. The study has two aims. First, we investigate whether the negative effect of ethnic heterogeneity on cooperation holds for concrete cooperative behavior in a real-world setting. Second, we test the most prominent psychological mechanism that has been proposed to explain the negative effects of heterogeneity on cooperation, namely in-group favoritism. We do so by experimentally varying the ethnicity and religion of the senders of letters. We find strong support for the negative effect of ethnic diversity on cooperation. We find no evidence, however, of in-group favoritism. Letters from Turkish or Muslim organizations were as often returned as those from German and Christian organizations, and the ethnic diversity effect was the same for all types of letters.

What theories explain variation in public opinion toward asylum seekers? We implement a survey experiment in which a representative sample of German residents evaluates vignettes of asylum seekers, which randomly vary attributes that speak to deservingness, economic and religious threat, and gender considerations of attitude formation. We find strong support for deservingness theories. Economic and religious threat theories also receive empirical support. Gender plays a negligible role. Importantly, we also document that economic and—to a lesser extent—religious threat considerations only matter when respondents evaluate economic refugees. By contrast, political refugees are welcomed nearly unconditionally. Our paper thus replicates key findings from Bansak, Hainmueller, and Hangartner (2016) and Czymara and Schmidt-Catran (2016) using a representative sample and points to an important interaction effect in public opinion formation toward asylum seekers: economic threat only gets activated when refugees’ deservingness is in doubt.

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In this study we compare rates of discrimination across German-born applicants from thirty-five ethnic groups in which various racial and religious treatment groups are embedded, this study allows us to better distinguish taste and statistical sources of discrimination, and to assess the relative importance of ethnicity, phenotype and religious affiliation as signals triggering discrimination. The study is based on applications to almost 6,000 job vacancies with male and female applicants in eight occupations across Germany. We test taste discrimination based on cultural value distance between groups against statistical discrimination based on average education levels and find that discrimination is mostly driven by the former. Based on this pattern, ethnic, racial and religious groups whose average values are relatively distant from the German average face the strongest discrimination. By contrast, employers do not treat minority groups with value patterns closer to Germany's different from ethnic German applicants without a migration background.