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In evolution, body plan complexity increases due to an increase in the number of individualized cell types. Yet, there is very little understanding of the mechanisms that produce this form of organismal complexity. One model for the origin of novel cell types is the sister cell-type model. According to this model, each cell type arises together with a sister cell type through specialization from an ancestral cell type. A key prediction of the sister cell-type model is that gene expression profiles of cell types exhibit tree structure. Here we present a statistical model for detecting tree structure in transcriptomic data and apply it to transcriptomes from ENCODE and FANTOM5. We show that transcriptomes of normal cells harbour substantial amounts of hierarchical structure. In contrast, cancer cell lines have less tree structure, suggesting that the emergence of cancer cells follows different principles from that of evolutionary cell-type origination.

Naturally occurring regulatory T (Treg) cells, which specifically express the transcription factor forkhead box P3 (Foxp3), are engaged in the maintenance of immunological self-tolerance and homeostasis. By transcriptional start site cluster analysis, we assessed here how genome-wide patterns of DNA methylation or Foxp3 binding sites were associated with Treg-specific gene expression. We found that Treg-specific DNA hypomethylated regions were closely associated with Treg up-regulated transcriptional start site clusters, whereas Foxp3 binding regions had no significant correlation with either up- or down-regulated clusters in nonactivated Treg cells. However, in activated Treg cells, Foxp3 binding regions showed a strong correlation with down-regulated clusters. In accordance with these findings, the above two features of activation-dependent gene regulation in Treg cells tend to occur at different locations in the genome. The results collectively indicate that Treg-specific DNA hypomethylation is instrumental in gene up-regulation in steady state Treg cells, whereas Foxp3 down-regulates the expression of its target genes in activated Treg cells. Thus, the two events seem to play distinct but complementary roles in Treg-specific gene expression.

BACKGROUND B7-1 (CD80) and B7-2 (CD86), which are costimulatory molecules in T-cell activation, play important roles in the differentiation of TH1- or TH2-phenotypes. These molecules were also suggested to play important roles in sensitization to a cedar pollen antigen by blocking studies using neutralizing antibodies, but there have been very few studies concerning the effects following induction by antigen. OBJECTIVE In this study, we investigated the roles of B7-1 and B7-2 in the differentiation of TH1 and TH2 subsets after stimulation with the antigen in subjects with cedar pollinosis. METHODS Skin-prick test was performed in nine subjects with pollinosis and in nine normal controls. Peripheral blood mononuclear cells (PBMCs) were isolated and stimulated with Japanese cedar pollen extract. After in vitro stimulation, the expression of CD80 and CD86 on CD19+ cells was analysed by two-colour flow cytometry. Culture supernatants were collected for all subjects and the production of type 1 and type 2 cytokines was measured by ELISA. RESULTS After in vitro stimulation, the expression of CD80 (B7-1) was upregulated in both pollinosis and control subjects, but no significant difference was observed between the two groups. On the other hand, CD86 (B7-2) was significantly upregulated following stimulation in pollinosis subjects (P = 0.02). A significantly higher level of IL-5 (P = 0.04) was produced by PBMCs of pollinosis subjects than by those of normal controls. A significantly higher level of interferon (IFN)-gamma (P = 0.03) was produced by PBMCs of normal controls than by those of pollinosis subjects. CONCLUSION These results indicated that TH2 response was predominant in pollinosis subjects, and that CD19+ cells of pollinosis subjects expressed higher levels of B7-2 than those of control subjects after in vitro stimulation. In pollinosis subjects, B7-2 rather than B7-1 may be the costimulatory molecule involved in allergen-induced activation of PBMCs.

24th European Photovoltaic Solar Energy Conference, 21-25 September 2009, Hamburg, Germany; 1410-1413, For recent improvements of the performance of crystalline Si solar cells, probability on the production is one of the most important standpoints of view. At the previous report, we have achieved 18.6% efficiency at multicrystalline Si solar cell, on the investigation of honeycomb texture etching, selective emitter, and small width electrode by screen printing. At this report, we investigated further improvements, based on new developing items on rear surface; passivation, selective contact, and back side reflection, by acceptable method for mass production in the future. As a result, we achieved over 19%. In near future, we will reach 19.5% by additional improvements on FF.

23rd European Photovoltaic Solar Energy Conference and Exhibition, 1-5 September 2008, Valencia, Spain; 1518-1521, In this paper, we present a highly efficient ultra-thin multi-crystalline silicon (mc-Si) solar cell with novel anti-reflection coatings. For improving the efficiency, new anti-reflection coatings and aluminum paste for screen printing were developed. The anti-reflection coatings were deposited from a dispersion of colloidal MgF2 and ZrO2 onto accomplished solar cells. The morphology of the particulate film was changed by deposition method, contributing the change of the refractive index. The reflection spectra of the solar cells after coating of the particulate films were successfully lowered with respect to those before depositions. As the result, short circuit current of the solar cells were improved. Together with the anti-reflection coatings, new aluminum paste for screen printing for rear electrode was utilized for ultra-thin mc-Si wafers. As the result, 17.4% in conversion efficiency was achieved with 100-m-thick mc-Si wafer in industrial size of 15 cm x 15 cm was achieved.

23rd European Photovoltaic Solar Energy Conference and Exhibition, 1-5 September 2008, Valencia, Spain; 1824-1828, In this paper, we present a novel process for fabricating a hemi-spherical shape for texture structure, namely known as honeycomb structure texture, for large area multi-crystalline silicon (mc-Si) solar cells. The method is composed of laser-patterning of mask film and wet chemical etching of wafer beneath the mask film through the pattern, substituting lithographic process usually used for fabricating such structure in small scale. After the texturization process, solar cells were made by utilizing conventional fabrication equipments, i.e. phosphorus diffusion in tube furnace, anti-reflection coating by chemical vapor deposition, front and rear electrodes formation by screen printing, and contact formation by furnace. The well-controlled texture with an optimized massproduction process for fabricating high-efficiency cell contributed to improving the conversion efficiency. As the result, 18.6% in conversion efficiency was achieved with mc-Si wafer in industrial size of 15 cm x 15 cm, independently confirmed by National Institute of Advanced Industrial Science and Technology (AIST). The main fabrication processes of the development described for the cell was as follows; 1) novel texturization method by combination of laser-patterning and wet chemical etching, 2) optimization of screen printing, metallization process of firing profile condition, and emitter diffusion.