Fish Chromatophores—From Molecular Motors to Animal Behavior

Video-microscopic measurement of cell-substratum traction forces generated by locomoting keratocytes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100146783 ◽

1993 ◽

Vol 51 ◽

pp. 188-189

Author(s):

Tim Oliver ◽

Michelle Leonard ◽

Juliet Lee ◽

Akira Ishihara ◽

Ken Jacobson

Keyword(s):

Silicone Rubber ◽

Molecular Motors ◽

Video Frame ◽

Traction Forces ◽

Cell Traction Forces ◽

Latex Beads ◽

Cell Traction ◽

Local Cell ◽

Microscopic Measurement ◽

Kinetics Of

We are using video-enhanced light microscopy to investigate the pattern and magnitude of forces that fish keratocytes exert on flexible silicone rubber substrata. Our goal is a clearer understanding of the way molecular motors acting through the cytoskeleton co-ordinate their efforts into locomotion at cell velocities up to 1 μm/sec. Cell traction forces were previously observed as wrinkles(Fig.l) in strong silicone rubber films by Harris.(l) These forces are now measureable by two independant means.In the first of these assays, weakly crosslinked films are made, into which latex beads have been embedded.(Fig.2) These films report local cell-mediated traction forces as bead displacements in the plane of the film(Fig.3), which recover when the applied force is released. Calibrated flexible glass microneedles are then used to reproduce the translation of individual beads. We estimate the force required to distort these films to be 0.5 mdyne/μm of bead movement. Video-frame analysis of bead trajectories is providing data on the relative localisation, dissipation and kinetics of traction forces.

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Facet Theory

European Psychologist ◽

10.1027/1016-9040.3.1.13 ◽

1998 ◽

Vol 3 (1) ◽

pp. 13-36 ◽

Cited By ~ 54

Author(s):

Ruth Guttman ◽

Charles W. Greenbaum

Keyword(s):

Data Analysis ◽

Animal Behavior ◽

Infant Development ◽

Facet Theory ◽

Structural Relationships ◽

Future Challenges ◽

Spatial Configurations ◽

Multidimensional Methods ◽

Definition Of ◽

Scalogram Analysis

This article gives an overview of Facet Theory, a systematic approach to facilitating theory construction, research design, and data analysis for complex studies, that is particularly appropriate to the behavioral and social sciences. Facet Theory is based on (1) a definitional framework for a universe of observations in the area of study; (2) empirical structures of observations within this framework; (3) a search for correspondence between the definitional system and aspects of the empirical structure for the observations. The development of Facet Theory and Facet Design is reviewed from early scale analysis and the Guttman Scale, leading to the concepts of “mapping sentence,” “universe of content,” “common range,” “content facets,” and nonmetric multidimensional methods of data analysis. In Facet Theory, the definition of the behavioral domain provides a rationale for hypothesizing structural relationships among variables employed in a study. Examples are presented from various areas of research (intelligence, infant development, animal behavior, etc.) to illustrate the methods and results of structural analysis with Smallest Space Analysis (SSA), Multidimensional Scalogram Analysis (MSA), and Partial Order Scalogram Analysis (POSA). The “radex” and “cylindrex” of intelligence tests are shown to be outstanding examples of predicted spatial configurations that have demonstrated the ubiquitous emergence of the same empirical structures in different studies. Further examples are given from studies of spatial abilities, infant development, animal behavior, and others. The use of Facet Theory, with careful construction of theory and design, is shown to provide new insights into existing data; it allows for the diagnosis and discrimination of behavioral traits and makes the generalizability and replication of findings possible, which in turn makes possible the discovery of lawfulness. Achievements, issues, and future challenges of Facet Theory are discussed.

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