13 research outputs found
A GDV COMPARISON OF HUMAN ENERGY FIELDS BEFORE AND AFTER STIMULATION OF SHEALY'S RINGS OF FIRE, EARTH, WATER, AIR, CRYSTAL
The objective of this research was to detect any change in the human energy field of the body as measured by the Gas Discharged Visualization (BEQ-GOV) device after the stimulation of the Shealy Rings of Fire, Earth, Water, Air, and Crystal. These Rings are each a set ofacupuncture points which were using the SheLi Tens Stimulator. A control group of sham, non-acupuncture points was also administered. This study used a comparison of the five rings, plus the control group of points, to examine the respective human energy field as displayed by the photon emission of the electrical magnetic field on the BEQ-GOV
The Physical Basis of Morphogenesis: Shaping and Patterning of Tissues via Cell-Cell Forces
Somehow, a fertilized egg develops into a multicellular organism with several organs that perform distinct functions. Much research regarding the development of multi-cellular organisms is chemical in nature: from networks of interacting intracellular bio-molecules to intercellular gradients of secreted chemicals. The role of mechanical forces, between neighboring cells or between cells and their environment, in development is often neglected. Here, based on models of mechanical forces during development, we study three processes: cone mosaic formation in zebrafish, apical stress fiber generation in Drosophila, and neural induction in stem cell colonies.
One of the most ordered vertebrate tissues, the zebrafish cone mosaic is a crystalline array of cells on the retinaâs hemispheric surface. The cone mosaic grows from the retinaâs rim; because of geometric constraints, defects form to maintain approximately constant cell spacing. These defects line up from the center to the periphery of the retina as it grows. A model based on chemical signaling in a fixed cell packing generates many excess defects; in contrast, a model based on repulsive interactions between cone cells reproduces the spatial distribution of defects observed in the retina. Unlike influential studies of the Drosophila R8 photoreceptor array, our findings suggest that cell motion governed by repulsive cell-cell interactions can play a key role in generating regular patterns in living systems.
Rather than repulsive intercellular interactions, in Drosophila we study how an entire tissue responds to morphogenetic forces from groups of neighboring cells. Apical stress fibers (aSFs) form to resist cell elongation. Importantly, the number of aSFs per cell scales with cell area to prevent elongation of large cells. To understand this scaling between mechanical response and cell area, we develop a model to predict the number of aSFs within any given cell based on its shape. Since aSFs nucleate and break at tricellular junctions (TCJs), the number of aSFs in each cell depends on the cellâs number of TCJs and the spacing between those TCJs. Our findings highlight how, based on area, cells scale their mechanical responses to resist deformations.
Finally, we study how mechanical stresses can bias cell fate. Our experimental system is a stem-cell-based model of neural induction, the process by which certain cells in the outer embryonic layer become neural. Two domains, the neural plate and the neural plate border (NPB), form. Motivated by experimental observations, we construct a mathematical model that couples cell fate and cell mechanical stress. In our model, cells at the colony boundary generate a fate pattern by transmitting forces to interior cells. Our mathematical model predicts that the NPBâs width depends non-monotonically on the stiffness of the cellsâ substrate. With experimental validation of this prediction, we argue that cells can communicate with each other via mechanical forces, biasing each otherâs fates.
Mechanical forces guide the shaping and patterning of tissues, from juvenile zebrafish to Drosophila embryos to human stem cells. Repulsion between cells of fixed fate can generate a crystalline array of cells. By helping cells resist deformations due to external stresses, apical stress fibers can tune a tissueâs final shape. Mechanical stresses, transmitted between cells, can produce fate patterns with a length scale that depends on the extracellular matrixâs stiffness. Starting as early as gastrulation, when three embryonic layers form, mechanical forces between cells shape the embryo and its constituent tissues into proper form.PHDBiophysicsUniversity of Michigan, Horace H. Rackham School of Graduate Studieshttp://deepblue.lib.umich.edu/bitstream/2027.42/162846/1/nunley_1.pd
Apical stress fibers enable a scaling between cell mechanical response and area in epithelial tissue
International audienc
Defect patterns on the curved surface of fish retinae suggest a mechanism of cone mosaic formation.
The outer epithelial layer of zebrafish retinae contains a crystalline array of cone photoreceptors, called the cone mosaic. As this mosaic grows by mitotic addition of new photoreceptors at the rim of the hemispheric retina, topological defects, called "Y-Junctions", form to maintain approximately constant cell spacing. The generation of topological defects due to growth on a curved surface is a distinct feature of the cone mosaic not seen in other well-studied biological patterns like the R8 photoreceptor array in the Drosophila compound eye. Since defects can provide insight into cell-cell interactions responsible for pattern formation, here we characterize the arrangement of cones in individual Y-Junction cores as well as the spatial distribution of Y-junctions across entire retinae. We find that for individual Y-junctions, the distribution of cones near the core corresponds closely to structures observed in physical crystals. In addition, Y-Junctions are organized into lines, called grain boundaries, from the retinal center to the periphery. In physical crystals, regardless of the initial distribution of defects, defects can coalesce into grain boundaries via the mobility of individual particles. By imaging in live fish, we demonstrate that grain boundaries in the cone mosaic instead appear during initial mosaic formation, without requiring defect motion. Motivated by this observation, we show that a computational model of repulsive cell-cell interactions generates a mosaic with grain boundaries. In contrast to paradigmatic models of fate specification in mostly motionless cell packings, this finding emphasizes the role of cell motion, guided by cell-cell interactions during differentiation, in forming biological crystals. Such a route to the formation of regular patterns may be especially valuable in situations, like growth on a curved surface, where the resulting long-ranged, elastic, effective interactions between defects can help to group them into grain boundaries