Mechanical Properties of Bovine Rhodopsin and Bacteriorhodopsin:  Possible Roles in Folding and Function†

Morphology serves as a ubiquitous proxy in macroevolutionary studies to identify potential adaptive processes and patterns. Inferences of functional significance of phenotypes or their evolution are overwhelmingly based on data from living taxa. Yet, correspondence between form and function has been tested in only a few model species, and those linkages are highly complex. The lack of explicit methodologies to integrate form and function analyses within a deep-time and phylogenetic context weakens inferences of adaptive morphological evolution, by invoking but not testing form–function linkages. Here, we provide a novel approach to test mechanical properties at reconstructed ancestral nodes/taxa and the strength and direction of evolutionary pathways in feeding biomechanics, in a case study of carnivorous mammals. Using biomechanical profile comparisons that provide functional signals for the separation of feeding morphologies, we demonstrate, using experimental optimization criteria on estimation of strength and direction of functional changes on a phylogeny, that convergence in mechanical properties and degree of evolutionary optimization can be decoupled. This integrative approach is broadly applicable to other clades, by using quantitative data and model-based tests to evaluate interpretations of function from morphology and functional explanations for observed macroevolutionary pathways.

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Cell and Tissue Mechanics

Tissue Engineering ◽

10.1093/oso/9780195141306.003.0010 ◽

2004 ◽

Author(s):

W. Mark Saltzman

Keyword(s):

Mechanical Properties ◽

Tissue Mechanics ◽

Elastic Materials ◽

Robert Hooke ◽

Hooke’S Law ◽

Original Shape ◽

Hooke's Law ◽

Natural Counterpart ◽

Tensile Elastic Modulus ◽

And Function

Mechanics is the branch of physics that is concerned with the action of forces on matter. Tissue engineers can encounter mechanics in various settings. Often, the mechanical properties of replacement biological materials must replicate the normal tissue: for example, there is limited use for a tissue-engineered bone that cannot support the load encountered by its natural counterpart. In addition, the mechanical properties of cells and cell–cell adhesions can determine the architecture of a tissue during development. This phenomenon can sometimes be exploited, since the final form of engineered tissues depends on the forces encountered during assembly and maturation. Finally, the mechanics of individual cells—and the molecular interactions that restrain cells—are important determinants of cell growth, movement, and function within an organism. This chapter introduces the basic elements of mechanics applied to biological systems. Some examples of biomechanical principles that appear to be important for tissue engineering are also provided. For further reading, comprehensive treatments of various aspects of biomechanics are also available. Consider an elongated object—for example, a segment of a biological tissue or a synthetic biomaterial—that is fixed at one end and suddenly exposed to a constant applied load. The material will change or deform in response to the load. For some materials, the deformation is instantaneous and, under conditions of low loading, deformation varies linearly with the magnitude of the applied force: . . . σ[≡F/A]= Eε (5-1) . . . where σ is the applied stress and ε is the resulting strain. This relationship is called Hooke’s law, after the British physicist Robert Hooke, and it describes the behavior of many elastic materials, such as springs, which deform linearly upon loading and recover their original shape upon removal of the load. The Young’s modulus or tensile elastic modulus, E, is a property of the material; some typical values are provided in Table 5.1. Not all elastic materials obey Hooke’s law (for example, rubber does not); some materials will recover their original shape, but strain is not linearly related to stress. Fortunately, many interesting materials do follow Equation 5-1, particularly if the deformations are small.

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Extraction of mechanical properties of materials through deep learning from instrumented indentation

Proceedings of the National Academy of Sciences ◽

10.1073/pnas.1922210117 ◽

2020 ◽

Vol 117 (13) ◽

pp. 7052-7062 ◽

Cited By ~ 14

Author(s):

Lu Lu ◽

Ming Dao ◽

Punit Kumar ◽

Upadrasta Ramamurty ◽

George Em Karniadakis ◽

...

Keyword(s):

Mechanical Properties ◽

Deep Learning ◽

Scaling Laws ◽

Three Dimensional ◽

Instrumented Indentation ◽

Multilayered Structures ◽

Mechanical Properties Of Materials ◽

Properties Of Materials ◽

Indentation Problem ◽

And Function

Instrumented indentation has been developed and widely utilized as one of the most versatile and practical means of extracting mechanical properties of materials. This method is particularly desirable for those applications where it is difficult to experimentally determine the mechanical properties using stress–strain data obtained from coupon specimens. Such applications include material processing and manufacturing of small and large engineering components and structures involving the following: three-dimensional (3D) printing, thin-film and multilayered structures, and integrated manufacturing of materials for coupled mechanical and functional properties. Here, we utilize the latest developments in neural networks, including a multifidelity approach whereby deep-learning algorithms are trained to extract elastoplastic properties of metals and alloys from instrumented indentation results using multiple datasets for desired levels of improved accuracy. We have established algorithms for solving inverse problems by recourse to single, dual, and multiple indentation and demonstrate that these algorithms significantly outperform traditional brute force computations and function-fitting methods. Moreover, we present several multifidelity approaches specifically for solving the inverse indentation problem which 1) significantly reduce the number of high-fidelity datasets required to achieve a given level of accuracy, 2) utilize known physical and scaling laws to improve training efficiency and accuracy, and 3) integrate simulation and experimental data for training disparate datasets to learn and minimize systematic errors. The predictive capabilities and advantages of these multifidelity methods have been assessed by direct comparisons with experimental results for indentation for different commercial alloys, including two wrought aluminum alloys and several 3D printed titanium alloys.

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Design principles of hair-like structures as biological machines

Journal of The Royal Society Interface ◽

10.1098/rsif.2018.0206 ◽

2018 ◽

Vol 15 (142) ◽

pp. 20180206 ◽

Cited By ~ 10

Author(s):

Madeleine Seale ◽

Cathal Cummins ◽

Ignazio Maria Viola ◽

Enrico Mastropaolo ◽

Naomi Nakayama

Keyword(s):

Mechanical Properties ◽

Surface Area ◽

Large Surface Area ◽

Structural Basis ◽

Basic Design ◽

Form And Function ◽

Mechanical Unit ◽

Wide Range ◽

Range Of Functions ◽

And Function

Hair-like structures are prevalent throughout biology and frequently act to sense or alter interactions with an organism's environment. The overall shape of a hair is simple: a long, filamentous object that protrudes from the surface of an organism. This basic design, however, can confer a wide range of functions, owing largely to the flexibility and large surface area that it usually possesses. From this simple structural basis, small changes in geometry, such as diameter, curvature and inter-hair spacing, can have considerable effects on mechanical properties, allowing functions such as mechanosensing, attachment, movement and protection. Here, we explore how passive features of hair-like structures, both individually and within arrays, enable diverse functions across biology. Understanding the relationships between form and function can provide biologists with an appreciation for the constraints and possibilities on hair-like structures. Additionally, such structures have already been used in biomimetic engineering with applications in sensing, water capture and adhesion. By examining hairs as a functional mechanical unit, geometry and arrangement can be rationally designed to generate new engineering devices and ideas.

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Mechanical properties and function of the paw pads of some mammals

Journal of Zoology ◽

10.1111/j.1469-7998.1986.tb03601.x ◽

1986 ◽

Vol 209 (3) ◽

pp. 405-419 ◽

Cited By ~ 64

Author(s):

R. McN. Alexander ◽

M. B. Bennett ◽

R. F. Ker

Keyword(s):

Mechanical Properties ◽

And Function

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Myogenic, mechanical and structural characteristics of resistance arterioles from healthy and ischaemic subjects

Clinical Science ◽

10.1042/cs20030203 ◽

2003 ◽

Vol 105 (6) ◽

pp. 683-689 ◽

Cited By ~ 5

Author(s):

P. COATS

Keyword(s):

Mechanical Properties ◽

Internal Control ◽

Regional Blood Flow ◽

Structural Characteristics ◽

Critical Limb Ischaemia ◽

Myogenic Tone ◽

Limb Ischaemia ◽

Active Pressure ◽

Chemical Stimuli ◽

And Function

In critical limb ischaemia (CLI), the ability to regulate regional blood flow in the diseased portion of the leg would appear to be severely compromised. Considering this, pressure-dependent myogenic and mechanical properties of resistance arterioles isolated from control subjects and from patients with CLI were studied. Using confocal microscopy and pressure myography, subcutaneous resistance arteriole structure and function were compared between subcutaneous arterioles isolated from healthy volunteers [control subcutaneous (CS)] and non-diseased proximal subcutaneous (PS; internal control) and distal subcutaneous (DS) arterioles from the diseased ischaemic part of the limb from patients with CLI. Significant wall atrophy was observed in DS arterioles compared with PS and CS arterioles. Passive pressure-dependent mechanical properties were significantly altered in the diseased arterioles compared with PS and CS arterioles. Active pressure-dependent myogenic tone was completely absent in DS arterioles. The atrophic structural remodelling in DS arterioles were correlated with the changes in vascular mechanics, but not with the ability of these arterioles to contract in response to chemical stimuli. However, active pressure-dependent myogenic tone was absent in the DS arterioles. The combination of altered pressure-dependent passive mechanical and active myogenic tone goes some way in explaining CLI sequelae and poor outcome following surgical revascularization experienced by these patients.

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Encapsulation of Mammalian Cells in Nanoporous Silica Gels: Interactions at the Biointerface

ASME 2012 Summer Bioengineering Conference, Parts A and B ◽

10.1115/sbc2012-80211 ◽

2012 ◽

Author(s):

Eduardo Reátegui ◽

Lisa Kasinkas ◽

Alptekin Aksan

Keyword(s):

Mechanical Properties ◽

Thermal Stability ◽

Energy Conversion ◽

Mammalian Cells ◽

Silica Gels ◽

Nanoporous Silica ◽

Energy Conversion Systems ◽

And Function ◽

Inorganic Matrix

Encapsulation of cells in nanoporous silica gels has shown great potential for the development of biotechnology applications such as biosensors, biocatalysis, bioremediation, energy conversion systems, and cellular therapies [1]. However, even though the inorganic matrix confers improved mechanical properties, chemical and thermal stability, and is resistant to microbial attacks, long-term viability and function after encapsulation remains as one of the principal setbacks of this technology [2].

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Chitin and cuticle proteins form the cuticular layer in the spinning duct of silk-spinning arthropods

10.1101/2021.11.04.466704 ◽

2021 ◽

Author(s):

Xin Wang ◽

Xiaoqian Xie ◽

Kang Xie ◽

Qingsong Liu ◽

Yi Li ◽

...

Keyword(s):

Mechanical Properties ◽

Multilayer Structure ◽

Peritrophic Matrix ◽

Shearing Stress ◽

Cuticle Proteins ◽

Negative Impacts ◽

Main Components ◽

And Function ◽

Cuticular Layer ◽

Silk Spinning

Chitin is found in the exoskeleton and peritrophic matrix of arthropods, but recent studies have also identified chitin in the spinning duct of silk-spinning arthropods. Here, we report the presence and function of chitin and cuticle proteins ASSCP1 and ASSCP2 in the spinning duct of silkworms. We show that chitin and these proteins are co-located in the cuticular layer of the spinning duct. Ultrastructural analysis indicates that the cuticular layer has a multilayer structure by layered stacking of the chitin laminae. After knocking down ASSCP1 and ASSCP2, the fine structure of this layer was disrupted, which had negative impacts on the mechanical properties of silk. This work clarifies the function of chitin in the spinning duct of silk-spinning arthropods. Chitin and cuticle proteins are the main components of the hard and rigid cuticular layer, providing the shearing stress during silk fibrillogenesis and regulating the final mechanical properties of silk.

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Extracellular Matrix Hydrogels Originated from Different Organs Mediate Tissue-Specific Properties and Function

International Journal of Molecular Sciences ◽

10.3390/ijms222111624 ◽

2021 ◽

Vol 22 (21) ◽

pp. 11624

Author(s):

Tzila Davidov ◽

Yael Efraim ◽

Rotem Hayam ◽

Jacopo Oieni ◽

Limor Baruch ◽

...

Keyword(s):

Mechanical Properties ◽

Extracellular Matrix ◽

Pluripotent Stem Cells ◽

Physical And Mechanical Properties ◽

Tissue Specific ◽

Gene Expression Analyses ◽

Composition Structure ◽

Induced Pluripotent ◽

And Function ◽

First Time

Porcine extracellular matrix (pECM)-derived hydrogels were introduced, in recent years, aiming to benefit the pECM’s microstructure and bioactivity, while controlling the biomaterial’s physical and mechanical properties. The use of pECM from different tissues, however, offers tissue-specific features that can better serve different applications. In this study, pECM hydrogels derived from cardiac, artery, pancreas, and adipose tissues were compared in terms of composition, structure, and mechanical properties. While major similarities were demonstrated between all the pECM hydrogels, their distinctive attributes were also identified, and their substantial effects on cell-ECM interactions were revealed. Furthermore, through comprehensive protein and gene expression analyses, we show, for the first time, that each pECM hydrogel supports the spontaneous differentiation of induced pluripotent stem cells towards the resident cells of its origin tissue. These findings imply that the origin of ECM should be carefully considered when designing a biomedical platform, to achieve a maximal bioactive impact.

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