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Modeling in Cellular Biomechanics
Published in Joseph D. Bronzino, Donald R. Peterson, Biomedical Engineering Fundamentals, 2019
Alexander A. Spector and Roger Tran-Son-Tay
e nucleus in the eukaryotic cell is enclosed by a nuclear envelope that consists of inner and outer nuclear membranes. Beneath the inner nuclear membrane lies the nuclear lamina, which is a network of laments consisting of lamin proteins. e nuclear lamina is believed to be responsible for the structural integrity of the nucleus. When the genes encoding nuclear envelop proteins are mutated, structural changes occur in the nuclear envelope, which leads to various diseases, such as Emeri-Dreifus muscular dystrophy and Hutchinson-Gilford progeria (early aging) syndrome. Rowat et al. (2005, 2006) used a micropipette aspiration technique and showed that the nuclear envelope undergoes deformations, maintaining structural stability when exposed to mechanical stress. ey developed a theory for a 2-D elastic material to characterize the elastic behavior of nuclear membranes. ey also found that the nuclear envelopes in mouse embryo broblasts lacking the inner nuclear membrane protein, emerin, are more fragile than those in wild-type cells. ey presented a model of nucleus stabilization in the pipette, combining their experimental results and theoretical considerations. Yokokawa et al. (2008) characterized the mechanical properties of the nuclear envelope of living HeLa cells in a culture medium by combining AFM imaging and force measurement. eir elasticity measurement showed that the nuclear envelope is so enough to absorb a large deformation by the AFM probe. Dahl et al. (2004) established
Computational and Experimental Approaches to Cellular and Subcellular Tracking at the Nanoscale
Published in Sarhan M. Musa, ®, 2018
Zeinab Al-Rekabi, Dominique Tremblay, Kristina Haase, Richard L. Leask, Andrew E. Pelling
These filaments are part of a subfamily of proteins containing more than 50 different members and have an average diameter of ~10nm. The common structure they share is the central a-helical domain, which consists of over 300 residues that form an entangled coil The dimers assemble themselves into a staggered array forming tetramers that connect end-to-end forming protofilaments. These in turn organize into ropelike structures, where each contains eight protofilaments with an average persistence length of about 1μm (Mucke et al. 2004). Intermediate filaments are relatively stable, and they are involved in providing tensile strength for the cell. In addition, they may be involved in specialized cell-cell junctions (Herrmann et al. 2007). For example, lamins, one of the various types of intermediate filaments form filamentous support inside the inner nuclear membrane; therefore, they are vital to the reassembly of the nuclear envelope after cell division (Georgatos and Blobel 1987; Herrmann et al. 2007; see Figure 9.2).
General Introductory Topics
Published in Vadim Backman, Adam Wax, Hao F. Zhang, A Laboratory Manual in Biophotonics, 2018
Vadim Backman, Adam Wax, Hao F. Zhang
There are several intranuclear structures that can be identified, including nuclear envelope, chromatin, and nucleolus. Let us examine these three structures in more detail. The nuclear envelope is a membrane-like structure that bounds the nucleus. It is also known as the perinuclear envelope, nuclear membrane, nucleolemma, or karyotheca. There are a number of significant differences between the nuclear envelope and the cell membrane. First, as opposed to the plasmalemma, the nuclear membrane is not a single but a double lipid bilayer. The two bilayers are separated by a 30-nm gap, which is called the perinuclear space or perinuclear cistern.
Les vertus des défauts: The scientific works of the late Mr Maurice Kleman analysed, discussed and placed in historical context, with particular stress on dislocation, disclination and other manner of local material disbehaviour
Published in Liquid Crystals Reviews, 2022
In cell biology, the so-called mitotic spindle describes the state of a eukaryotic cell during cell division. We remind the reader that eukaryotes are often (not always, although the reverse is the case) multi-cellular organisms with the property that the genetic material (chromosomes are contained inside a nucleus which is bounded by the nuclear envelope consisting a lipid bilayer. During cell division microtubules (long polymers) align between two spindle poles which act as the organising centres for the new nuclei. The separated (‘single helix’) chromosomes travel along the aligned microtubules to the spindle poles, eventually creating identical daughter cells.
Nonviral gene delivery using PAMAM dendrimer conjugated with the nuclear localization signal peptide derived from human papillomavirus type 11 E2 protein
Published in Journal of Biomaterials Science, Polymer Edition, 2021
Jeil Lee, Yong-Eun Kwon, Jaegi Kim, Dong Woon Kim, Hwanuk Guim, Jehyeong Yeon, Jin-Cheol Kim, Joon Sig Choi
Therapeutic genes must be delivered to the nuclear region for successful gene therapy. However, nonviral vectors have difficulties in selectively delivering DNA molecules into the nuclear region, limiting their application in genetic medicine. Nonviral gene delivery is inhibited by membranous barriers; one of these, the nuclear envelope, consists of two lipid bilayer membranes and a nuclear pore complex (NPC), limiting the entry of molecules larger than 9 nm. NLS is a tag sequence that enables the transport of proteins from the cytoplasm to the nuclear region and permits the active transport of molecules up to 39 nm [29]. Since the size of the cationic polymer/pCN-Luci polyplexes was too large to directly penetrate the NPC pores, we hypothesized that PAMAM derivatives conjugated with NLS peptides/pCN-Luci polyplexes would be localized in the perinuclear region because of their size, and subsequently delivered to the nuclear region when the nuclear envelope disappears during mitosis. In our previous study, polyplexes of PAMAM derivatives conjugated with NLS peptides and pCN-Luci showed high transfection efficiency and perinuclear localization. A series of experiments and previous findings indicate that each factor, such as enhanced cellular uptake and proton-buffering capacity, affects the transfection efficiency of PAMAM derivatives modified with NLS peptides, which showed a lower proton-buffering capacity than PEI 25 kDa [17–19]. If proton-buffering capacity was the main reason for the increased transfection efficiency, PAMAM derivatives modified with NLS peptides should have a buffering capacity similar to that of PEI (25 kDa). Therefore, the improved transfection efficiency of RKRAR- and RKRARH-PAMAM G2 may be a product of the combined effects of these three factors.