Simple Display System of Mechanical Properties of Cells and Their Dispersion

The mechanical properties of cells are unique indicators of their states and functions. Though, it is difficult to recognize the degrees of mechanical properties, due to small size of the cell and broad distribution of the mechanical properties. Here, we developed a simple virtual reality system for presenting the mechanical properties of cells and their dispersion using a haptic device and a PC. This system simulates atomic force microscopy (AFM) nanoindentation experiments for floating cells in virtual environments. An operator can virtually position the AFM spherical probe over a round cell with the haptic handle on the PC monitor and feel the force interaction. The Young's modulus of mesenchymal stem cells and HEK293 cells in the floating state was measured by AFM. The distribution of the Young's modulus of these cells was broad, and the distribution complied with a log-normal pattern. To represent the mechanical properties together with the cell variance, we used log-normal distribution-dependent random number determined by the mode and variance values of the Young's modulus of these cells. The represented Young's modulus was determined for each touching event of the probe surface and the cell object, and the haptic device-generating force was calculated using a Hertz model corresponding to the indentation depth and the fixed Young's modulus value. Using this system, we can feel the mechanical properties and their dispersion in each cell type in real time. This system will help us not only recognize the degrees of mechanical properties of diverse cells but also share them with others

Real-time and Single Fibril Observation of the Formation of Amyloid β Spherulitic Structures

This research was originally published in the Journal of Biological Chemistry. Tadato Ban, Kenichi Morigaki, Hisashi Yagi, Takashi Kawasaki, Atsuko Kobayashi, Shunsuke Yuba, Hironobu Naiki and Yuji Goto. Real-time and Single Fibril Observation of the Formation of Amyloid β Spherulitic Structures. J. Biol. Chem. 2006; 281, 33677–33683. © the American Society for Biochemistry and Molecular Biolog

In vivo visualization of the lymphatic vessels in pFLT4-EGFP transgenic medaka.

FMS-like tyrosine kinase 4 (FLT4) is a marker for lymphatic vessels and some high endothelial venules in human adult tissues. We generated a transgenic medaka fish in which the lymphatic vessels and some blood vessels are visible in vivo by transferring the promoter of medaka flt4 driving the expression of enhanced green fluorescent protein (EGFP), using a see-through medaka line. To do this, we identified and cloned medaka flt4, and generated a construct in which the promoter was the 4-kb region upstream of the translation initiation site. The fluorescent signal of EGFP could be observed with little background, and the expression pattern correlated well with that of flt4 determined by whole-mount RNA in situ hybridization. Because a see-through medaka line is transparent until adult, the model is useful for visualizing the lymphatic vessels not only in embryo and fry, but also in adult. This model will be a useful tool for analyzing lymphatic development

Transgenic medaka fish which mimic the endogenous expression of neuronal kinesin, KIF5A.

Intracellular transport is spatiotemporally controlled by microtubule-dependent motor proteins, including kinesins. In order to elucidate the mechanisms controlling kinesin expression, it is important to analyze their genomic regulatory regions. In this study, we cloned the neuronal tissue-specific kinesin in medaka fish and generated transgenic fish which mimic endogenous neuronal kinesin expression in order to elucidate the mechanisms which regulate kinesin expression. Searches for medaka neuronal orthologues by RT-PCR identified a candidate gene expressed only in neuronal tissues. Using BAC clones, we determined the cDNA sequence and the gene structure of the candidate neuronal kinesin. Evolutionary analysis indicated that the candidate gene encoded medaka KIF5Aa. The endogenous medaka orthologue was found to be expressed only in the nervous system, including the brain and spinal cord, while expression of KIF5Ab was not exclusive to neuronal tissues. Transgenic (Tg) medaka that expressed EGFP under the control of the 6.9kbp 5' and 1.9kbp 3' flanking regions of the KIF5Aa gene showed characteristic expression throughout the nervous system, including the brain, spinal cord, olfactory pit, eye and cranial nerve. Immunohistological analysis showed that EGFP expression in Tg fish co-localized with expression of HuC/D, a neuronal marker. These results demonstrate that the 6.9kbp 5' and 1.9kbp 3' flanking regions of medaka KIF5Aa have neuronal-specific promoter activity mimicking endogenous expression of medaka KIF5Ab. This transgenic fish strain will be useful for further functional analysis of the effects of these regulatory regions on gene expression

The Biocompatible Anchor for Membrane (BAM) system.

<p>(A) Chemical structure of BAM. It comprises an oleyl group, an NHS reactive ester group, and a hydrophilic PEG linker. (B) Diagram of the BAM-coated substrate. BAM molecules are fixed on the BSA-coated substrate via coupling with the NHS ester of BAM to the amino group of BSA. The surface oleyl group enters the plasma membrane of the cell. Then, the cell is anchored onto the BAM substrate. (C) Phase contrast micrograph of hMSCs on the BAM substrate. The floating cells were anchored to the substrate, maintaining their round shape. The left upper object is the AFM cantilever.</p