In many species, including Arabidopsis, heterochromatin often comprises repetitive DNA elements, such as arrays of ribosomal DNA (rDNA). Repetitive regions pose a risk in meiosis since recombination between them can lead to gross genomic rearrangements. However, meiotic recombination at rDNA arrays and other heterochromatic repeat regions is blocked by not well understood mechanisms. Here, we have identified RAD21.2, an α-kleisin subunit of cohesin, as a repressor of meiotic recombination at the rDNA regions in Arabidopsis. We show that RAD21.2 co-localizes with heterochromatic factors and is specifically enriched at rDNA repeats, which are devoid of the meiosis specific α-kleisin REC8, needed for recombination. Knocking down RAD21.2, we find that REC8 moves into the nucleolus organizing regions (NORs), where we see an increase of RAD51 recombinase foci numbers. Concomitantly, we find extensive rearrangements of the NORs and the offspring of these plants have large variation in rDNA copy numbers demonstrating that RAD21.2 is necessary for transgenerational genome stability.
This issue of ATR considers numerous instances in which economic historians and historians of capitalism have turned to architecture as evidence of the workings of economic and financial systems. This collective position paper stems from the attempt to engage more directly with these disciplines; an attempt that was first manifested in the symposium "Built Orders of Finance, Risk and Racial Capitalism," held online in early 2022. How are built orders shaped by processes of financialization, actuarial calculations of risk and the conditions of racial capitalism? How do built orders mobilize specific economic regimes? What kinds of evidence can be enlisted to discern the constitutive relationships established and maintained between architecture and regimes of finance? What scales are implied in these relationships? What is involved in their historicization? This article invites future conversations between the fields of scholarship it canvases to more comprehensively apprehend the terms, conditions, and histories of financialized space.
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