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The genome inside the eukaryotic cells is guarded by a unique shell structure, called the nuclear envelope (NE), made of lipid membranes. This structure has an ultra torus topology with thousands of torus-shaped holes that imparts the structure a high flexural stiffness. Inspired from this biological design, here we present a novel “torene” architecture to design lightweight shell structures with ultra-stiffness for engineering applications. We perform finite element analyses on classic benchmark problems to investigate the mechanics of torene shells. This study reveals that the torene shells can achieve one order of magnitude or higher flexural stiffness than traditional shells with the same amount of material. This novel geometric strategy opens new avenues to exploit additive manufacturing to design lightweight shell structures for extreme mechanical environments.
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Geometry of the nuclear envelope determines its flexural stiffness
During closed mitosis in fission yeast, growing microtubules push onto the nuclear envelope to deform it, which results in fission into two daughter nuclei. The resistance of the envelope to bending, quantified by the flexural stiffness, helps determine the microtubule-dependent nuclear shape transformations. Computational models of envelope mechanics have assumed values of the flexural stiffness of the envelope based on simple scaling arguments. The validity of these estimates is in doubt, however, owing to the complex structure of the nuclear envelope. Here, we performed computational analysis of the bending of the nuclear envelope under applied force using a model that accounts for envelope geometry. Our calculations show that the effective bending modulus of the nuclear envelope is an order of magnitude larger than a single membrane and approximately five times greater than the nuclear lamina. This large bending modulus is in part due to the 45 nm separation between the two membranes, which supports larger bending moments in the structure. Further, the effective bending modulus is highly sensitive to the geometry of the nuclear envelope, ranging from twofold to an order magnitude larger than the corresponding single membrane. These results suggest that spatial variations in geometry and mechanical environment of the envelope may cause a spatial distribution of flexural stiffness in the same nucleus. Overall, our calculations support the possibility that the nuclear envelope may balance significant mechanical stresses in yeast and in cells from higher organisms.
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- PAR ID:
- 10188445
- Date Published:
- Journal Name:
- Molecular Biology of the Cell
- Volume:
- 31
- Issue:
- 16
- ISSN:
- 1059-1524
- Page Range / eLocation ID:
- 1815 to 1821
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1091/mbc.E20-02-0163
