25 research outputs found

    Single mutation to a sex pheromone receptor provides adaptive specificity between closely related moth species

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    Sex pheromone communication, acting as a prezygotic barrier to mating, is believed to have contributed to the speciation of moths and butterflies in the order Lepidoptera. Five decades after the discovery of the first moth sex pheromone, little is known about the molecular mechanisms that underlie the evolution of pheromone communication between closely related species. Although Asian and European corn borers (ACB and ECB) can be interbred in the laboratory, they are behaviorally isolated from mating naturally by their responses to subtly different sex pheromone isomers, (E)-12- and (Z)-12-tetradecenyl acetate and (E)-11- and (Z)-11-tetradecenyl acetate (ACB: E12, Z12; ECB; E11, Z11). Male moth olfactory systems respond specifically to the pheromone blend produced by their conspecific females. In vitro, ECB(Z) odorant receptor 3 (OR3), a sex pheromone receptor expressed in male antennae, responds strongly to E11 but also generally to the Z11, E12, and Z12 pheromones. In contrast, we show that ACB OR3, a gene that has been subjected to positive selection (ω = 2.9), responds preferentially to the ACB E12 and Z12 pheromones. In Ostrinia species the amino acid residue corresponding to position 148 in transmembrane domain 3 of OR3 is alanine (A), except for ACB OR3 that has a threonine (T) in this position. Mutation of this residue from A to T alters the pheromone recognition pattern by selectively reducing the E11 response ∼14-fold. These results suggest that discrete mutations that narrow the specificity of more broadly responsive sex pheromone receptors may provide a mechanism that contributes to speciation

    Locating the altruistic voter: context, egocentric voting, and support for the Conservative Party at the 1997 General Election in England and Wales

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    Egocentric economic voting models are widely used in studies of voting behaviour in Great Britain: they suggest that people whose standard of living has risen recently as a perceived consequence of government policies are more likely to vote for the government's return to office than are those who blame government policies for a decline in their living standards. But many people whose living standards have increased vote against the government. Analyses reported here, using specially constructed bespoke neighbourhoods around the homes of respondents to the 1997 British Election Study, show that the latter group mainly live in areas of high local unemployment. This suggests a pattern of altruistic voting, of people who are prospering personally, but whose neighbours are not, voting against the incumbent government -- a pattern confirmed by statistical analyses of both egocentric and sociotropic voting.

    Stability coefficients of a missile at angles of attack

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    Identification of two human dimethylarginine dimethylaminohydrolases with distinct tissue distributions and homology with microbial arginine deiminases.

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    Methylarginines inhibit nitric oxide synthases (NOS). Cellular concentrations of methylarginines are determined in part by the activity of dimethylarginine dimethylaminohydrolase (DDAH; EC 3.5.3. 18). We have cloned human DDAH and identified and expressed a second novel DDAH isoform (DDAH I and II respectively). DDAH I predominates in tissues that express neuronal NOS. DDAH II predominates in tissues expressing endothelial NOS. These results strengthen the hypothesis that methylarginine concentration is actively regulated and identify molecular targets for the tissue and cell-specific regulation of methylarginine concentration
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