Presentation of Various Tactile Sensations Using Micro-Needle Electrotactile Display

Tactile displays provoke tactile sensations by artificially stimulating tactile receptors. While many types of tactile displays have been developed, electrotactile displays that exploit electric stimulation can be designed to be thin, light, flexible and thus, wearable. However, the high voltages required to stimulate tactile receptors and limited varieties of possible sensations pose problems. In our previous work, we developed an electrotactile display using a micro-needle electrode array that can drastically reduce the required voltage by penetrating through the high-impedance stratum corneum painlessly, but displaying various tactile sensations was still a challenge. In this work, we demonstrate presentation of tactile sensation of different roughness to the subjects, which is enabled by the arrangement of the electrodes; the needle electrodes are on the fingertip and the ground electrode is on the fingernail. With this arrangement, the display can stimulate the tactile receptors that are located not only in the shallow regions of the finger but also those in the deep regions. It was experimentally revealed that the required voltage was further reduced compared to previous devices and that the roughness presented by the display was controlled by the pulse frequency and the switching time, or the stimulation flow rate. The proposed electrotactile display is readily applicable as a new wearable haptic device for advanced information communication technology.     

Distinct functions of the two specificity determinants in replication initiation of plasmids ColE2-P9 and ColE3-CA38

The plasmid ColE2-P9 Rep protein specifically binds to the cognate replication origin to initiate DNA replication. The replicons of the plasmids ColE2-P9 and ColE3-CA38 are closely related, although the actions of the Rep proteins on the origins are specific to the plasmids. The previous chimera analysis identified two regions, regions A and B, in the Rep proteins and two sites, alpha and beta, in the origins as specificity determinants and showed that when each component of the region A-site alpha pair and the region B-site beta pair is derived from the same plasmid, plasmid DNA replication is efficient. It is also indicated that the replication specificity is mainly determined by region A and site alpha. By using an electrophoretic mobility shift assay, we demonstrated that region B and site beta play a critical role for stable Rep protein-origin binding and, furthermore, that 284-Thr in this region of the ColE2 Rep protein and the corresponding 293-Trp of the ColE3 Rep protein mainly determine the Rep-origin binding specificity. On the other hand, region A and site alpha were involved in the efficient unwinding of several nucleotide residues around site alpha, although they were not involved in the stable binding of the Rep protein to the origin. Finally, we discussed how the action of the Rep protein on the origin involving these specificity determinants leads to the plasmid-specific replication initiation.     

Label-free quantitative proteomics using large peptide data sets generated by nanoflow liquid chromatography and mass spectrometry

We developed an integrated platform consisting of machinery and software modules that can apply vast amounts of data generated by nanoflow LC-MS to differential protein expression analyses. Unlabeled protein samples were completely digested with modified trypsin and separated by low speed (200 nl/min) one-dimensional HPLC. Mass spectra were obtained every 1 s by using the survey mode of a hybrid Q-TOF mass spectrometer and displayed in a two-dimensional plane with m/z values along the x axis, and retention time was displayed along the y axis. The time jitter of nano-LC was adjusted using newly developed software based on a dynamic programming algorithm. The comprehensiveness (60,000-160,000 peaks above the predetermined threshold detectable in 60-microg cell protein samples), reproducibility (average coefficient of variance of 0.35-0.39 and correlation coefficient of over 0.92 between duplicates), and accurate quantification with a wide dynamic range (over 10(3)) of our platform warrant its application to various types of experimental and translational proteomics.     

STS-95 Space Experiments (plants and cell biology).

We report the outline of Space Experiments conducted on Space Shuttle (STS-95) launched in autumn of 1998. In this STS-95 mission, Japanese astronaut Dr. Chiaki Mukai achieved her 2nd space flight and conducted a part of 82 space experiments including Japanese experiments. US astronaut Senator John Glenn also achieved his second space flight, 36 years after his first space flight. Senator Glenn was a leader of the original (the first) 7 US astronauts and very famous in US because he succeeded US first orbital space flight around the earth. NASDA had started the project of space experiment using STS-95 at the summer of 1997, therefore we had only one year for the all preparation Yamashita, et al. Biological Sciences in Space, Vol.12 No.3(1998). Scientific results will be reported by investigators, therefore we report here how we had been developing the space experiment plan, on board operation procedure and ground operations including ground control experiments about four plant experiments and one cell biology experiment.     

Keratinocyte growth factor

Keratinocyte growth factor (KGF) is a member of the heparin-binding fibroblast growth factor family (FGF-7) with a distinctive pattern of target-cell specificity. Studies performed in cell culture suggested that KGF was mitogenically active only on epithelial cells, albeit from a variety of tissues. In contrast, KGF was produced solely by cells of mesenchymal origin, leading to the hypothesis that it might function as a paracrine mediator of mesenchymal-epithelial communication. Biochemical analysis and molecular cloning established that the KGF receptor (KGFR) was a tyrosine kinase isoform encoded by the fgfr-2 gene. Many detailed investigations of KGF and KGFR expression in whole tissue and cell lines largely substantiated the pattern initially perceived in vitro of mesenchymal and epithelial distribution, respectively. Moreover, functional assays in organ culture and in vivo and studies of KGF regulation by sex sterorid hormones reinforced the idea that KGF acts predominantly on epithelial cells to elicit a variety of responses including proliferation, migration and morphogenesis.     

The solution structure of horseshoe crab antimicrobial peptide tachystatin B with an inhibitory cystine-knot motif.

Tachystatin B is an antimicrobial and a chitin-binding peptide isolated from the Japanese horseshoe crab (Tachypleus tridentatus) consisting of two isopeptides called tachystatin B1 and B2. We have determined their solution structures using NMR experiments and distance geometry calculations. The 20 best converged structures of tachystatin B1 and B2 exhibited root mean square deviations of 0.46 and 0.49 A, respectively, for the backbone atoms in Cys(4)-Arg(40). Both structures have identical conformations, and they contain a short antiparallel beta-sheet with an inhibitory cystine-knot (ICK) motif that is distributed widely in the antagonists for voltage-gated ion channels, although tachystatin B does not have neurotoxic activity. The structural homology search provided several peptides with structures similar to that of tachystatin B. However, most of them have the advanced functions such as insecticidal activity, suggesting that tachystatin B may be a kind of ancestor of antimicrobial peptide in the molecular evolutionary history. Tachystatin B also displays a significant structural similarity to tachystatin A, which is member of the tachystatin family. The structural comparison of both tachystatins indicated that Tyr(14) and Arg(17) in the long loop between the first and second strands might be the essential residues for binding to chitin.