Japanese Supplier Relations: A Comparative Perspective

This paper describes major characteristics of Japanese supplier relations in a comparative perspective. The supplier relations in Japan, particularly automobile industry, are examined in comparison with those in the United States. The primary purpose of the study is to characterize significant features of Japanese supplier relations and to provide economic rationale for those relationships. In addition, comparing supplier relations in Japan and the U.S., convergence in the nature of those are discussed. Significant features of Japanese supplier relations are characterized: long-term relationships and commitments; forced competition among few suppliers; transaction-specific investments in plant, equipment, and human capital; significant involvement of suppliers in product development with sharing of information. Supplier relations in the U.S. are changing and moving close to the Japanese counterpart. There has been a limited, yet noticeable, convergence in the nature of U.S. and Japanese supplier relations.Long-term relationships, Procurement, Supplier relations, Transaction-specific investments

Different integration site structures between L1 protein-mediated retrotransposition in cis and retrotransposition in trans

Abstract Background Long interspersed nuclear element-1 (LINE-1 or L1) is a dominant repetitive sequence in the human genome. Besides mediating its own retrotransposition, L1 can mobilize Alu and messenger RNA (mRNA) in trans, and probably also SVA and non-coding RNA. The structures of L1 copies and trans-mobilized retrocopies are variable and can be classified into three categories: full-length; 5'-truncated; and 5'-inverted insertions. These structures may be generated by different 5' integration mechanisms. Results In this study, a method to correctly characterize insertions with short target site duplications (TSDs) is developed and extranucleotides, TSDs and microhomologies (MHs) at junctions were analysed for the three types of insertions. Only 5'-truncated L1 insertions were found to be associated with short TSDs. Both full-length and 5'-truncated retrotransposed sequences in trans, including Alu, SVA and mRNA retrocopies and also full-length and 5'-inverted L1, were not associated with short TSDs, indicating the difference of 5' attachment between retrotransposition in cis and retrotransposition in trans. Target sequence analysis suggested that short TSDs were generated in an L1 endonuclease-dependent manner. The MHs were longer for 5'-inverted L1 than for 5'-truncated L1, indicating less dependence on annealing in 5'-truncated L1 insertions. Conclusions The results suggest that insertions flanked by short TSDs occur more often coupled with the insertion of 5'-truncated L1 than with those of other types of insertions in vivo. The method used in this study can be used to characterize elements without any apparent boundary structures.</p

Adsorption and Desorption of Bioactive Proteins on Hydroxyapatite for Protein Delivery Systems

Hydroxyapatite (HA) is a precursor of bone and has been studied as a biomaterial. We attempted HA to apply to protein delivery systems. In this study, the association and dissociation properties of two types of bioactive proteins, cytochrom c and insulin, to HA were investigated. Cytochrom c was less associated with HA than insulin, which was easily released from it. However, the release of insulin from HA was slow. Insulin was released from HA at pH 7.4 more rapidly than at pH 3. The association and dissociation properties might be influenced by the size, solubility and net charge of protein. HA is a potential protein carrier with controlled release

Crypton transposons: identification of new diverse families and ancient domestication events

<p>Abstract</p> <p>Background</p> <p>"Domestication" of transposable elements (TEs) led to evolutionary breakthroughs such as the origin of telomerase and the vertebrate adaptive immune system. These breakthroughs were accomplished by the adaptation of molecular functions essential for TEs, such as reverse transcription, DNA cutting and ligation or DNA binding. <it>Cryptons </it>represent a unique class of DNA transposons using tyrosine recombinase (YR) to cut and rejoin the recombining DNA molecules. <it>Cryptons </it>were originally identified in fungi and later in the sea anemone, sea urchin and insects.</p> <p>Results</p> <p>Herein we report new <it>Cryptons </it>from animals, fungi, oomycetes and diatom, as well as widely conserved genes derived from ancient <it>Crypton </it>domestication events. Phylogenetic analysis based on the YR sequences supports four deep divisions of <it>Crypton </it>elements. We found that the domain of unknown function 3504 (DUF3504) in eukaryotes is derived from <it>Crypton </it>YR. DUF3504 is similar to YR but lacks most of the residues of the catalytic tetrad (R-H-R-Y). Genes containing the DUF3504 domain are potassium channel tetramerization domain containing 1 (<it>KCTD1</it>), <it>KIAA1958</it>, zinc finger MYM type 2 (<it>ZMYM2</it>), <it>ZMYM3</it>, <it>ZMYM4</it>, glutamine-rich protein 1 (<it>QRICH1</it>) and "without children" (<it>WOC</it>). The <it>DUF3504 </it>genes are highly conserved and are found in almost all jawed vertebrates. The sequence, domain structure, intron positions and synteny blocks support the view that <it>ZMYM2</it>, <it>ZMYM3</it>, <it>ZMYM4</it>, and possibly <it>QRICH1</it>, were derived from <it>WOC </it>through two rounds of genome duplication in early vertebrate evolution. <it>WOC </it>is observed widely among bilaterians. There could be four independent events of <it>Crypton </it>domestication, and one of them, generating <it>WOC</it>/<it>ZMYM</it>, predated the birth of bilaterian animals. This is the third-oldest domestication event known to date, following the domestication generating telomerase reverse transcriptase (<it>TERT</it>) and <it>Prp8</it>. Many <it>Crypton</it>-derived genes are transcriptional regulators with additional DNA-binding domains, and the acquisition of the DUF3504 domain could have added new regulatory pathways via protein-DNA or protein-protein interactions.</p> <p>Conclusions</p> <p><it>Cryptons </it>have contributed to animal evolution through domestication of their YR sequences. The DUF3504 domains are domesticated YRs of animal <it>Crypton </it>elements.</p

A novel method of cultivating cardiac myocytes in agarose microchamber chips for studying cell synchronization

We have developed a new method that enables agar microstructures to be used to cultivate cardiac myocyte cells in a manner that allows their connection patterns to be controlled. Non-contact three-dimensional photo-thermal etching with a 1064-nm infrared focused laser beam was used to form the shapes of agar microstructures. This wavelength was selected as it is not absorbed by water or agar. Identical rat cardiac myocytes were cultured in adjacent microstructures connected by microchannels and the interactions of asynchronous beating cardiac myocyte cells observed. Two isolated and independently beating cardiac myocytes were shown to form contacts through the narrow microchannels and by 90 minutes had synchronized their oscillations. This occurred by one of the two cells stopping their oscillation and following the pattern of the other cell. In contrast, when two sets of synchronized beating cells came into contact, those two sets synchronized without any observable interruptions to their rhythms. The results indicate that the synchronization process of cardiac myocytes may be dependent on the community size and network pattern of these cells

Stability of beating frequency in cardiac myocytes by their community effect measured by agarose microchamber chip

To understand the contribution of community effect on the stability of beating frequency in cardiac myocyte cell groups, the stepwise network formation of cells as the reconstructive approach using the on-chip agarose microchamber cell microcultivation system with photo-thermal etching method was applied. In the system, the shapes of agarose microstructures were changed step by step with photo-thermal etching of agarose-layer of the chip using a 1064-nm infrared focused laser beam to increase the interaction of cardiac myocyte cells during cultivation. First, individual rat cardiac myocyte in each microstructure were cultivated under isolated condition, and then connected them one by one through newly-created microchannels by photo-thermal etching to compare the contribution of community size for the magnitude of beating stability of the cell groups. Though the isolated individual cells have 50% fluctuation of beating frequency, their stability increased as the number of connected cells increased. And finally when the number reached to eight cells, they stabilized around the 10% fluctuation, which was the same magnitude of the tissue model cultivated on the dish. The result indicates the importance of the community size of cells to stabilize their performance for making cell-network model for using cells for monitoring their functions like the tissue model

Families of transposable elements, population structure and the origin of species

<p>Abstract</p> <p>Background</p> <p>Eukaryotic genomes harbor diverse families of repetitive DNA derived from transposable elements (TEs) that are able to replicate and insert into genomic DNA. The biological role of TEs remains unclear, although they have profound mutagenic impact on eukaryotic genomes and the origin of repetitive families often correlates with speciation events. We present a new hypothesis to explain the observed correlations based on classical concepts of population genetics.</p> <p>Presentation of the hypothesis</p> <p>The main thesis presented in this paper is that the TE-derived repetitive families originate primarily by genetic drift in small populations derived mostly by subdivisions of large populations into subpopulations. We outline the potential impact of the emerging repetitive families on genetic diversification of different subpopulations, and discuss implications of such diversification for the origin of new species.</p> <p>Testing the hypothesis</p> <p>Several testable predictions of the hypothesis are examined. First, we focus on the prediction that the number of diverse families of TEs fixed in a representative genome of a particular species positively correlates with the cumulative number of subpopulations (demes) in the historical metapopulation from which the species has emerged. Furthermore, we present evidence indicating that human AluYa5 and AluYb8 families might have originated in separate proto-human subpopulations. We also revisit prior evidence linking the origin of repetitive families to mammalian phylogeny and present additional evidence linking repetitive families to speciation based on mammalian taxonomy. Finally, we discuss evidence that mammalian orders represented by the largest numbers of species may be subject to relatively recent population subdivisions and speciation events.</p> <p>Implications of the hypothesis</p> <p>The hypothesis implies that subdivision of a population into small subpopulations is the major step in the origin of new families of TEs as well as of new species. The origin of new subpopulations is likely to be driven by the availability of new biological niches, consistent with the hypothesis of punctuated equilibria. The hypothesis also has implications for the ongoing debate on the role of genetic drift in genome evolution.</p> <p>Reviewers</p> <p>This article was reviewed by Eugene Koonin, Juergen Brosius and I. King Jordan.</p