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Xenopus egg extracts are a powerful in vitro tool for studying complex biological processes, including nuclear reconstitution, nuclear membrane and pore assembly, and spindle assembly. Extracts have been further used to demonstrate a moonlighting regulatory role for nuclear import receptors or importins on these cell cycle assembly events. Here we show that exportins can also play a role in these events. Addition of Crm1, Exportin-t, or Exportin-5 decreased nuclear pore assembly in vitro. RanQ69L-GTP, a constitutively active form of RanGTP, ameliorated inhibition. Both Crm1 and Exportin-t inhibited fusion of nuclear membranes, again counteracted by RanQ69L-GTP. In mitotic extracts, Crm1 and Exportin-t negatively impacted spindle assembly. Pulldowns from the extracts using Crm1- or Exportin-t-beads revealed nucleoporins known to be essential for both nuclear pore and spindle assembly, with RanQ69L-GTP decreasing a subset of these target interactions. This study suggests a model where exportins, like importins, can regulate major mitotic assembly events. more...

Xist is the master regulator of X-Chromosome Inactivation (XCI), the mammalian dosage compensation mechanism that silences one of the two X chromosomes in a female cell. XCI is established during early embryonic development. Xist transgene (Tg) integrated into an autosome can induce transcriptional silencing of flanking genes; however, the effect and mechanism of Xist RNA on autosomal sequence silencing remain elusive. In this study, we investigate an autosomal integration of Xist Tg that is compatible with mouse viability but causes male sterility in homozygous transgenic mice. We observed ectopic Xist expression in the transgenic male cells along with a transcriptional reduction of genes clustered in four segments on the mouse chromosome 1 (Chr 1). RNA/DNA Fluorescent in situ Hybridization (FISH) and chromosome painting confirmed that Xist Tg is associated with chromosome 1. To determine the spreading mechanism of autosomal silencing induced by Xist Tg on Chr 1, we analyzed the positions of the transcriptionally repressed chromosomal sequences relative to the Xist Tg location inside the cell nucleus. Our results show that the transcriptionally repressed chromosomal segments are closely proximal to Xist Tg in the three-dimensional nucleus space. Our findings therefore support a model that Xist directs and maintains long-range transcriptional silencing facilitated by the three-dimensional chromosome organization. more...

Knowledge producers of Romani ethnicity, like the people to whom they belong, both inside and outside normative frameworks governing development modes and the transmission of knowledge, are hampered profoundly by three fundamental ethical credentials of being: the power to say, the power to act, and the power to collect their own lives into a comprehensible and acceptable story. Due to an historical process of epistemological alienation which appeared with the Enlightenment, it has been impossible for Romani subjects to have as their duty, their responsibility to the world, the power to act. Through a “Foucauldian archaeology” on Romani iconography in the Louvre and Prado collections, and using as a methodological presupposition historical and epistemological decolonial thought, this paper will try to advance the understanding of the genealogy of abnormativity by referring to the study of the Romani motif in the arts. The analysis of the pictographic treatment allows us to understand how those “topoi” responded to religious, ethical-moral, and geopolitical imperatives of majority society in a dialectic that oscillates between formal presence and ontological absence from the fifteenth to nineteenth centuries. The arrival of the Roma in fifteenth-century Europe, in full epistemological caesura, between a dying hermeneutic age and the age of the nascent cogito, conditions a radical change in the consideration of Romani alterity. Indeed, this alteration of the Romani alterity experience by mainstream societies constitutes a paradigmatic example of epistemicidiary structural dynamics and idiomicidiaries born of the slime of “historical modernity”. more...

Mammalian X chromosome dosage compensation balances X-linked gene products between sexes and is coordinated by the long noncoding RNA (lncRNA) Xist. Multiple cis and trans-acting factors modulate Xist expression; however, the primary competence factor responsible for activating Xist remains a subject of dispute. The lncRNA Jpx is a proposed competence factor, yet it remains unknown if Jpx is sufficient to activate Xist expression in mice. Here, we utilize a novel transgenic mouse system to demonstrate a dose-dependent relationship between Jpx copy number and ensuing Jpx and Xist expression. By localizing transcripts of Jpx and Xist using RNA Fluorescence in situ Hybridization (FISH) in mouse embryonic cells, we provide evidence of Jpx acting in both trans and cis to activate Xist. Our data contribute functional and mechanistic insight for lncRNA activity in mice, and argue that Jpx is a competence factor for Xist activation in vivo. more...