Spatio-temporal imaging of cell fate dynamics in single plant cells using luminescence microscope.

Stem cell fates are spatio-temporally regulated during plant development. Time-lapse imaging of fluorescence reporters is the most widely used method for spatio-temporal analysis of biological processes. However, excitation light for imaging fluorescence reporters causes autofluorescence and photobleaching. Unlike fluorescence reporters, luminescence proteins do not require excitation light, and therefore offer an alternative reporter for long-term and quantitative spatio-temporal analysis. We established an imaging system for luciferase, which enabled monitoring cell fate marker dynamics during vascular development in a vascular cell induction system called VISUAL. Single cells expressing the cambium marker, proAtHB8:ELUC, had sharp luminescence peaks at different time points. Furthermore, dual-color luminescence imaging revealed spatio-temporal relationships between cells that differentiated into xylem or phloem, and cells that transitioned from procambium to cambium. This imaging system enables not only the detection of temporal gene expression, but also facilitates monitoring of spatio-temporal dynamics of cell identity transitions at the single cell level.

VISUAL-CC system uncovers the role of GSK3 as an orchestrator of vascular cell type ratio in plants.

The phloem transports photosynthetic assimilates and signalling molecules. It mainly consists of sieve elements (SEs), which act as "highways" for transport, and companion cells (CCs), which serve as "gates" to load/unload cargos. Though SEs and CCs function together, it remains unknown what determines the ratio of SE/CC in the phloem. Here we develop a new culture system for CC differentiation in Arabidopsis named VISUAL-CC, which almost mimics the process of the SE-CC complex formation. Comparative expression analysis in VISUAL-CC reveals that SE and CC differentiation tends to show negative correlation, while total phloem differentiation is unchanged. This varying SE/CC ratio is largely dependent on GSK3 kinase activity. Indeed, gsk3 hextuple mutants possess many more SEs and fewer CCs, whereas gsk3 gain-of-function mutants partially increase the CC number. Taken together, GSK3 activity appears to function as a cell-fate switch in the phloem, thereby balancing the SE/CC ratio.

Deep Imaging Analysis in VISUAL Reveals the Role of YABBY Genes in Vascular Stem Cell Fate Determination.

Stem cells undergo cell division and differentiation to ensure organized tissue development. Because plant cells are immobile, plant stem cells ought to decide their cell fate prior to differentiation, to locate specialized cells in the correct position. In this study, based on a chemical screen, we isolated a novel secondary cell wall indicator BF-170, which binds to lignin and can be used to image in vitro and in situ xylem development. Use of BF-170 to observe the vascular differentiation pattern in the in vitro vascular cell induction system, VISUAL, revealed that adaxial mesophyll cells of cotyledons predominantly generate ectopic xylem cells. Moreover, phloem cells are abundantly produced on the abaxial layer, suggesting the involvement of leaf adaxial-abaxial polarity in determining vascular cell fate. Analysis of abaxial polarity mutants highlighted the role of YAB3, an abaxial cell fate regulator, in suppressing xylem and promoting phloem differentiation on the abaxial domains in VISUAL. Furthermore, YABBY family genes affected in vivo vascular development during the secondary growth. Our results denoted the possibility that such mediators of spatial information contribute to correctly determine the cell fate of vascular stem cells, to conserve the vascular pattern of land plants.

[Contribution of hospital pharmacists for home parenteral nutrition--the case we were concerned with pharmaceutical management and support in mixing of injections].

Home parenteral nutrition (HPN) is a useful measure when cancer patients are hoping to have a transition from the hospital to a home medical care arrangement. A contribution of pharmacist performing HPN to a patient is to manage pharmaceuticals so that an appropriate medicine is used for not only the prescription design of the infusion solution but also to give a relaxation care. Based on the patient information record gathered by a home-visit nursing care program, we tried to study what pharmacists could do to help the patient after he was discharged.

Elevated expression level of 60-kDa subunit of tRNA-guanine transglycosylase in colon cancer.

tRNA-guanine transglycosylase (TGT) is an enzyme which synthesizes a modified nucleoside, queuosine, by exchanging the base moiety of guanosine for queuine in tRNA. We have reported that the expression level of the 60-kDa subunit of TGT (TGT60kD) is elevated in leukemic cells, however, there is no other report on the expression of TGT60kD in cancer cells. The expression levels of the TGT60kD protein are elevated in four of the five colon cancer cell lines and 83% of colon cancer tissues compared with normal tissues. The expression levels of the TGT60kD protein decreased in two colon cancer cell lines, after cell differentiation was induced. A marked positive staining of cancer cells in colon tissues was observed, and the subcellular staining pattern was mainly cytosolic. These data suggest that the role of TGT60kD in colon carcinogenesis.