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SUMMARY:Diffusion-mediated coarsening can explain meiotic crossover interf
 erence - Martin  Howard (John Innes Centre\, Norwich)
DTSTART:20230704T140000Z
DTEND:20230704T143000Z
UID:TALK201124@talks.cam.ac.uk
DESCRIPTION:In most organisms\, the number and distribution of crossovers 
 that occur during meiosis are tightly controlled. All chromosomes must rec
 eive at least one &lsquo\;obligatory crossover&rsquo\; and crossovers are 
 prevented from occurring near one another by &lsquo\;crossover interferenc
 e&rsquo\;. However\, the mechanistic basis of this phenomenon of crossover
  interference has remained mostly mysterious. Using quantitative super-res
 olution cytogenetics and mathematical modelling\, we have investigated cro
 ssover positioning in the Arabidopsis thaliana wild-type\, an over-express
 or of the conserved E3 ligase HEI10\, and a hei10 heterozygous line. We sh
 ow that crossover positions can be explained by a predictive\, diffusion-m
 ediated coarsening model\, in which large\, approximately evenly-spaced HE
 I10 foci grow at the expense of smaller\, closely-spaced clusters. We prop
 ose this coarsening process explains many aspects of Arabidopsis crossover
  positioning\, including crossover interference. Consistent with this mode
 l\, we also demonstrate that crossover positioning can be predictably modi
 fied in vivo simply by altering HEI10 dosage\, with higher and lower dosag
 e leading to weaker and stronger crossover interference\, respectively. As
  HEI10 is a conserved member of the RING finger protein family that functi
 ons in the interference-sensitive pathway for crossover formation\, we ant
 icipate that similar mechanisms may regulate crossover positioning in dive
 rse eukaryotes.
LOCATION:Seminar Room 1\, Newton Institute
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