Accurate placement of extracellular materials is a critical part of cellular development. To study how cells achieve this accuracy, we use formation of pollen apertures as a model. In Arabidopsis (), three regions on the pollen surface lack deposition of pollen wall exine and develop into apertures. In developing pollen, Arabidopsis (INP1) protein acts as a marker for the preaperture domains, assembling there into three punctate lines. To understand the mechanism of aperture formation, we studied the dynamics of INP1 expression and localization and its relationship with the membrane domains at which it assembles. We found that INP1 assembly occurs after meiotic cytokinesis at the interface between the plasma membrane and the overlying callose wall, and requires the normal callose wall formation. Sites of INP1 localization coincide with positions of protruding membrane ridges in proximity to the callose wall. Our data suggest that INP1 is a late-acting factor involved in keeping specific membrane domains next to the callose wall to prevent formation of exine at these sites.

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Groves & Iris Meier (2020) LINC-complex mediated positioning of the vegetative nucleus is involved in calcium and ROS signaling in Arabidopsis pollen tubes,

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How do varying levels of inter-group contact affect voter preferences in connection with ethnically radical political candidates and parties? Two competing hypotheses have emerged in the last 60 years: the first, known as the group threat hypothesis, argues that voters from an ethnic or religious group in more ethnically or racially heterogeneous districts will exhibit stronger preferences for ethnically radical political candidates. The contact hypothesis argues that groups living in mixed localities are actually less likely to support ethnic radicals. Both perspectives have found empirical support, but no previous study has offered a theoretical explanation for two seemingly contradictory conclusions. We specify just such a theory, arguing that the effect of district level integration is conditioned by the direction of a group’s share of the national population. We test this theory quantitatively using electoral data from Northern Ireland between 1983 and 2010.