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Leighton MP, Kreplak L, Rutenberg AD. Torsion and bistability of double-twist elastomers. SOFT MATTER 2023; 19:6376-6386. [PMID: 37577969 DOI: 10.1039/d3sm00554b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 08/15/2023]
Abstract
We investigate the elastic properties of anisotropic elastomers with a double-twist director field, which is a model for collagen fibrils or blue phases. We observe a significant Poynting-like effect, coupling torsion (fibril twist) and extension. For freely-rotating boundary conditions, we identify a structural bistability at very small extensional strains which undergoes a saddle-node bifurcation at a critical strain - at approximately 1% strain for a parameterization appropriate for collagen fibrils. With clamped boundary conditions appropriate for many experimental setups, the bifurcation is not present. We expect significant helical shape effects when fixed torsion does not equal the equilibrium torsion of freely-rotating boundary conditions, due to residual torques.
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Affiliation(s)
- Matthew P Leighton
- Department of Physics, Simon Fraser University, Burnaby, British Columbia, V5A 1S6, Canada
| | - Laurent Kreplak
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada.
| | - Andrew D Rutenberg
- Department of Physics and Atmospheric Science, Dalhousie University, Halifax, Nova Scotia, B3H 4R2, Canada.
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2
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Daniels G, Fraser A, Westgate GE. How different is human hair? A critical appraisal of the reported differences in global hair fibre characteristics and properties towards defining a more relevant framework for hair type classification. Int J Cosmet Sci 2023; 45:50-61. [PMID: 36374002 DOI: 10.1111/ics.12819] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Revised: 09/15/2022] [Accepted: 09/25/2022] [Indexed: 11/16/2022]
Abstract
This review critically appraises the reported differences in human hair fibre within three related domains of research: hair classification approaches, fibre characteristics and properties. The most common hair classification approach is based on geo-racial origin, defining three main groups: African, Asian and Caucasian hair. This classification does not account sufficiently for the worldwide hair diversity and intergroups variability in curl, shape, size and colour. A global classification into eight curl types has been proposed but may be too complex for reproducibility. Beyond that, hair cross-sectional shape and area have been found to have an inverse relation to curl: straighter fibres are circular with larger cross-sectional area, whilst the curlier fibres are elliptical with smaller cross-sectional area. These geometrical differences have been associated with bilateral vs homogenous distribution of cortical cell in curly vs straight hair respectively. However, there is no sufficient data demonstrating significant differences in hair amino composition, but proteomic studies are reporting associations of some proteins with curly hair. Eumelanin's relative abundance has been reported in all hair colours except for red hair which has a high pheomelanin content. Higher tensile and fatigue strength of straight hair are reported, however, curly hair fragility is attributed to knotting, and crack and flow formations rather than the structural variations. African hair has been found to have the highest level of lipids, whilst the water sorption of Caucasian hair is the highest, and that of Asian hair the lowest. Not all comparative studies clearly report their hair sampling approaches. Therefore, to strengthen the robustness of comparative studies and to facilitate cross-study data comparisons, it is recommended that the following hair defining characteristics are reported in studies: hair cross sectional diameter/area, curl type, hair assembly colour, as well as where possible donor data (age/gender) and sample pooling approach.
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Affiliation(s)
- Gabriela Daniels
- Cosmetic Science Research Group, London College of Fashion, London, UK
| | - Ashiana Fraser
- Cosmetic Science Research Group, London College of Fashion, London, UK
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Velamoor S, Mitchell A, Bostina M, Harland D. Processing hair follicles for transmission electron microscopy. Exp Dermatol 2021; 31:110-121. [PMID: 34351648 DOI: 10.1111/exd.14439] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2021] [Revised: 07/30/2021] [Accepted: 08/02/2021] [Indexed: 11/30/2022]
Abstract
Transmission electron microscopy (TEM) has greatly advanced our knowledge of hair growth and follicle morphogenesis, but complex preparations such as fixation, dehydration and embedding compromise ultrastructure. While recent developments with cryofixation have been shown to preserve the ultrastructure of biological materials close to native state, they do have limitations. This review will focus on each stage of the TEM sample preparation process and their effects on the structural integrity of follicles.
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Affiliation(s)
- Sailakshmi Velamoor
- Proteins and Metabolites, AgResearch Limited, Lincoln, New Zealand.,Microbiology and Immunology, University of Otago, Dunedin, New Zealand
| | - Allan Mitchell
- Otago Micro and Nano Imaging, University of Otago, Dunedin, New Zealand
| | - Mihnea Bostina
- Microbiology and Immunology, University of Otago, Dunedin, New Zealand.,Otago Micro and Nano Imaging, University of Otago, Dunedin, New Zealand
| | - Duane Harland
- Proteins and Metabolites, AgResearch Limited, Lincoln, New Zealand
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Yamamoto M, Sakamoto Y, Honda Y, Koike K, Nakamura H, Matsumoto T, Ando S. De novo filament formation by human hair keratins K85 and K35 follows a filament development pattern distinct from cytokeratin filament networks. FEBS Open Bio 2021; 11:1299-1312. [PMID: 33605551 PMCID: PMC8091587 DOI: 10.1002/2211-5463.13126] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Revised: 01/24/2021] [Accepted: 02/18/2021] [Indexed: 11/23/2022] Open
Abstract
In human hair follicles, the hair‐forming cells express 16 hair keratin genes depending on the differentiation stages. K85 and K35 are the first hair keratins expressed in cortical cells at the early stage of the differentiation. Two types of mutations in the gene encoding K85 are associated with ectodermal dysplasia of hair and nail type. Here, we transfected cultured SW‐13 cells with human K85 and K35 genes and characterized filament formation. The K85–K35 pair formed short filaments in the cytoplasm, which gradually elongated and became thicker and entangled around the nucleus, indicating that K85–K35 promotes lateral association of short intermediate filaments (IFs) into bundles but cannot form IF networks in the cytoplasm. Of the K85 mutations related to ectodermal dysplasia of hair and nail type, a two‐nucleotide (C1448T1449) deletion (delCT) in the protein tail domain of K85 interfered with the K85–K35 filament formation and gave only aggregates, whereas a missense mutation (233A>G) that replaces Arg78 with His (R78H) in the head domain of K85 did not interfere with the filament formation. Transfection of cultured MCF‐7 cells with all the hair keratin gene combinations, K85–K35, K85(R78H)–K35 and K85(delCT)–K35, as well as the individual hair keratin genes, formed well‐developed cytoplasmic IF networks, probably by incorporating into the endogenous cytokeratin IF networks. Thus, the unique de novo assembly properties of the K85–K35 pair might play a key role in the early stage of hair formation.
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Affiliation(s)
- Masaki Yamamoto
- Faculty of Biotechnology and Life Science, Sojo University, Kumamoto, Japan
| | - Yasuko Sakamoto
- Faculty of Biotechnology and Life Science, Sojo University, Kumamoto, Japan
| | - Yuko Honda
- Faculty of Medicine, Saga University, Japan
| | - Kenzo Koike
- Hair Care Research Center, KAO Corporation, Tokyo, Japan
| | - Hideaki Nakamura
- Faculty of Pharmaceutical Science, Sojo University, Kumamoto, Japan
| | | | - Shoji Ando
- Faculty of Biotechnology and Life Science, Sojo University, Kumamoto, Japan
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Eldirany SA, Lomakin IB, Ho M, Bunick CG. Recent insight into intermediate filament structure. Curr Opin Cell Biol 2020; 68:132-143. [PMID: 33190098 DOI: 10.1016/j.ceb.2020.10.001] [Citation(s) in RCA: 49] [Impact Index Per Article: 12.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/01/2020] [Revised: 09/22/2020] [Accepted: 10/05/2020] [Indexed: 12/17/2022]
Abstract
Intermediate filaments (IFs) are key players in multiple cellular processes throughout human tissues. Their biochemical and structural properties are important for understanding filament assembly mechanisms, for interactions between IFs and binding partners, and for developing pharmacological agents that target IFs. IF proteins share a conserved coiled-coil central-rod domain flanked by variable N-terminal 'head' and C-terminal 'tail' domains. There have been several recent advances in our understanding of IF structure from the study of keratins, glial fibrillary acidic protein, and lamin. These include discoveries of (i) a knob-pocket tetramer assembly mechanism in coil 1B; (ii) a lamin-specific coil 1B insert providing a one-half superhelix turn; (iii) helical, yet flexible, linkers within the rod domain; and (iv) the identification of coil 2B residues required for mature filament assembly. Furthermore, the head and tail domains of some IFs contain low-complexity aromatic-rich kinked segments, and structures of IFs with binding partners show electrostatic surfaces are a major contributor to complex formation. These new data advance the connection between IF structure, pathologic mutations, and clinical diseases in humans.
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Affiliation(s)
- Sherif A Eldirany
- Department of Dermatology, Yale University, New Haven, CT, 06520, USA
| | - Ivan B Lomakin
- Department of Dermatology, Yale University, New Haven, CT, 06520, USA
| | - Minh Ho
- Department of Dermatology, Yale University, New Haven, CT, 06520, USA
| | - Christopher G Bunick
- Department of Dermatology, Yale University, New Haven, CT, 06520, USA; Department of Molecular Biophysics and Biochemistry, Yale University, New Haven, CT, 06520, USA.
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VELAMOOR S, RICHENA M, MITCHELL A, LEQUEUX S, BOSTINA M, HARLAND D. High‐pressure freezing followed by freeze substitution of a complex and variable density miniorgan: the wool follicle. J Microsc 2020; 278:18-28. [DOI: 10.1111/jmi.12875] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/17/2019] [Revised: 01/16/2020] [Accepted: 02/06/2020] [Indexed: 01/15/2023]
Affiliation(s)
- S. VELAMOOR
- Lincoln Research Centre, Food & Bio‐Based ProductsAgresearch Limited Lincoln New Zealand
- Department of Immunology and MicrobiologyUniversity of Otago Dunedin New Zealand
| | - M. RICHENA
- Lincoln Research Centre, Food & Bio‐Based ProductsAgresearch Limited Lincoln New Zealand
| | - A. MITCHELL
- Otago Micro and Nano Imaging UnitUniversity of Otago Dunedin New Zealand
| | - S. LEQUEUX
- Otago Micro and Nano Imaging UnitUniversity of Otago Dunedin New Zealand
| | - M. BOSTINA
- Department of Immunology and MicrobiologyUniversity of Otago Dunedin New Zealand
- Otago Micro and Nano Imaging UnitUniversity of Otago Dunedin New Zealand
| | - D. HARLAND
- Lincoln Research Centre, Food & Bio‐Based ProductsAgresearch Limited Lincoln New Zealand
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