114th iCeMS Seminar/CeMI Seminar Series 31: Prof. Kazuhiro Maeshima

How is 2-m-long genomic DNA organized into a mitotic chromosome or nucleus? The nucleosome fiber has long been assumed to be folded into a 30 nm chromatin fiber, and further helically folded larger fiber. However, when we observed frozen hydrated human mitotic cells using cryoelectron microscopy (cryo-EM), no higher-order structures including 30 nm chromatin fibers were found. To further investigate the bulk structure of mitotic chromosomes, we performed small-angle X-ray scattering (SAXS) at SPring-8. No structural feature larger than 11 nm was detected, even on a chromosome-diameter scale (~1 µm). We also found a similar scattering pattern in interphase nuclei of HeLa cells in the range up to ~275 nm. Our findings suggest a common structural feature in interphase and mitotic chromatins: compact and irregular folding of nucleosome fibers occurs without a 30 nm chromatin structure.

Lecturer Title	Prof. Kazuhiro Maeshima Biological Macromolecules Laboratory National Institute of Genetics, Japan Title: How is a long strand of genomic DNA organized into a nucleus or chromosome?
Date / Time	August 10, 2012 / 10:30-12:00
Venue	Room 119, Research Building No. 1/Project Lab (#32), Kyoto University Directions
Flyer	PDF (151KB)
Host	Institute for Integrated Cell-Material Sciences (iCeMS), Kyoto University
Co-Host	Center for Frontier Medicine, Global COE Program, Kyoto University
Contact	iCeMS Harada Lab harada-g@icems.kyoto-u.ac.jp